Reliability of a Novel High Intensity One Leg Dynamic Exercise Protocol to Measure Muscle Endurance

PubMed Central

Lepers, Romuald; Marcora, Samuele M.

2016-01-01

We recently developed a high intensity one leg dynamic exercise (OLDE) protocol to measure muscle endurance and investigate the central and peripheral mechanisms of muscle fatigue. The aims of the present study were to establish the reliability of this novel protocol and describe the isokinetic muscle fatigue induced by high intensity OLDE and its recovery. Eight subjects performed the OLDE protocol (time to exhaustion test of the right leg at 85% of peak power output) three times over a week period. Isokinetic maximal voluntary contraction torque at 60 (MVC60), 100 (MVC100) and 140 (MVC140) deg/s was measured pre-exercise, shortly after exhaustion (13 ± 4 s), 20 s (P20) and 40 s (P40) post-exercise. Electromyographic (EMG) signal was analyzed via the root mean square (RMS) for all three superficial knee extensors. Mean time to exhaustion was 5.96 ± 1.40 min, coefficient of variation was 8.42 ± 6.24%, typical error of measurement was 0.30 min and intraclass correlation was 0.795. MVC torque decreased shortly after exhaustion for all angular velocities (all P < 0.001). MVC60 and MVC100 recovered between P20 (P < 0.05) and exhaustion and then plateaued. MVC140 recovered only at P40 (P < 0.05). High intensity OLDE did not alter maximal EMG RMS of the three superficial knee extensors during MVC. The results of this study demonstrate that this novel high intensity OLDE protocol could be reliably used to measure muscle endurance, and that muscle fatigue induced by high intensity OLDE should be examined within ~ 30 s following exhaustion. PMID:27706196

Effects of long term Tai Chi practice and jogging exercise on muscle strength and endurance in older people.

PubMed

Xu, D Q; Li, J X; Hong, Y

2006-01-01

To investigate the influence of regular Tai Chi (TC) practice and jogging on muscle strength and endurance in the lower extremities of older people. Twenty one long term older TC practitioners were compared with 18 regular older joggers and 22 sedentary counterparts. Maximum concentric strength of knee flexors and extensors was tested at angular velocities of 30 degrees/s and 120 degrees/s. Ankle dorsiflexors and plantar flexors were tested at 30 degrees/s and the dynamic endurance of the knee flexors and extensors was assessed at a speed of 180 degrees/s. The differences in the muscle strength of the knee joint amongst the three experimental groups were significant at the higher velocity. The strengths of knee extensors and flexors in the control group were significantly lower than those in the jogging group and marginally lower than those in the TC group. For the ankle joint, the subjects in both the TC and jogging groups generated more torque in their ankle dorsiflexors. In addition, the muscle endurance of knee extensors was more pronounced in TC practitioners than in controls. Regular older TC practitioners and joggers showed better scores than the sedentary controls on most muscle strength and endurance measures. However, the magnitude of the exercise effects on muscles might depend on the characteristics of different types of exercise.

The susceptibility of the knee extensors to eccentric exercise-induced muscle damage is not affected by leg dominance but by exercise order.

PubMed

Hody, S; Rogister, B; Leprince, P; Laglaine, T; Croisier, J-L

2013-09-01

The aims of this study were first to compare the response of dominant and non-dominant legs to eccentric exercise and second, to examine whether there is an effect of exercise order on the magnitude of symptoms associated with intense eccentric protocols. Eighteen young men performed three sets of 30 maximal eccentric isokinetic (60° s(-1)) contractions of the knee extensors (range of motion, ROM: 0°-100°, 0 = full extension) using either dominant or non-dominant leg. They repeated a similar eccentric bout using the contralateral leg 6 weeks later. The sequence of leg's use was allocated to create equally balanced groups. Four indirect markers of muscle damage including subjective pain intensity, maximal isometric strength, muscle stiffness and plasma creatine kinase (CK) activity were measured before and 24 h after exercise. All markers changed significantly following the eccentric bout performed either by dominant or non-dominant legs, but no significant difference was observed between legs. Interestingly, the comparison between the first and second eccentric bouts revealed that muscle soreness (-42%, P<0.001), CK activity (-62%, P<0.05) and strength loss (-54%, P<0.01) were significantly lower after the second bout. This study suggests that leg dominance does not influence the magnitude of exercise-induced muscle damage and supports for the first time the existence of a contralateral protection against exercise-induced muscle damage in the lower limbs. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Superior Effects of Eccentric to Concentric Knee Extensor Resistance Training on Physical Fitness, Insulin Sensitivity and Lipid Profiles of Elderly Men

PubMed Central

Chen, Trevor Chung-Ching; Tseng, Wei-Chin; Huang, Guan-Ling; Chen, Hsin-Lian; Tseng, Kuo-Wei; Nosaka, Kazunori

2017-01-01

It has been reported that eccentric training of knee extensors is effective for improving blood insulin sensitivity and lipid profiles to a greater extent than concentric training in young women. However, it is not known whether this is also the case for elderly individuals. Thus, the present study tested the hypothesis that eccentric training of the knee extensors would improve physical function and health parameters (e.g., blood lipid profiles) of older adults better than concentric training. Healthy elderly men (60–76 years) were assigned to either eccentric training or concentric training group (n = 13/group), and performed 30–60 eccentric or concentric contractions of knee extensors once a week. The intensity was progressively increased over 12 weeks from 10 to 100% of maximal concentric strength for eccentric training and from 50 to 100% for concentric training. Outcome measures were taken before and 4 days after the training period. The results showed that no sings of muscle damage were observed after any sessions. Functional physical fitness (e.g., 30-s chair stand) and maximal concentric contraction strength of the knee extensors increased greater (P ≤ 0.05) after eccentric training than concentric training. Homeostasis model assessment, oral glucose tolerance test and whole blood glycosylated hemoglobin showed improvement of insulin sensitivity only after eccentric training (P ≤ 0.05). Greater (P ≤ 0.05) decreases in fasting triacylglycerols, total, and low-density lipoprotein cholesterols were evident after eccentric training than concentric training, and high-density lipoprotein cholesterols increased only after eccentric training. These results support the hypothesis and suggest that it is better to focus on eccentric contractions in exercise medicine. PMID:28443029

Comparison of joint kinetics during free weight and flywheel resistance exercise.

PubMed

Chiu, Loren Z F; Salem, George J

2006-08-01

The most common modality for resistance exercise is free weight resistance. Alternative methods of providing external resistance have been investigated, in particular for use in microgravity environments such as space flight. One alternative modality is flywheel inertial resistance, which generates resistance as a function of the mass, distribution of mass, and angular acceleration of the flywheel. The purpose of this investigation was to characterize net joint kinetics of multijoint exercises performed with a flywheel inertial resistance device in comparison to free weights. Eleven trained men and women performed the front squat, lunge, and push press on separate days with free weight or flywheel resistance, while instrumented for biomechanical analysis. Front squats performed with flywheel resistance required greater contribution of the hip and ankle, and less contribution of the knee, compared to free weight. Push presses performed with flywheel resistance had similar impulse requirements at the knee compared to free weight, but greater impulse requirement at the hip and ankle. As used in this investigation, flywheel inertial resistance increases the demand on the hip extensors and ankle plantarflexors and decreases the mechanical demand on the knee extensors for lower extremity exercises such as the front squat and lunge. Exercises involving dynamic lower and upper extremity actions, such as the push press, may benefit from flywheel inertial resistance, due to the increased mechanical demand on the knee extensors.

Muscle power is an important measure to detect deficits in muscle function in hip osteoarthritis: a cross-sectional study.

PubMed

Bieler, Theresa; Magnusson, Stig Peter; Christensen, Helle Elisabeth; Kjaer, Michael; Beyer, Nina

2017-07-01

To investigate between-leg differences in hip and thigh muscle strength and leg extensor power in patients with unilateral hip osteoarthritis. Further, to compare between-leg differences in knee extensor strength and leg extensor power between patients and healthy peers. Seventy-two patients (60-87 years) with radiographic and symptomatic hip osteoarthritis not awaiting hip replacement and 35 healthy peers (63-82 years) were included. Hip and thigh muscle strength and leg extensor power were measured in patients and knee extensor strength and leg extensor power in healthy. The symptomatic extremity in patients was significantly (p < 0.05, paired t-test) weaker compared with the non-symptomatic extremity for five hip muscles (8-17%), knee extensors (11%) and leg extensor power (19%). Healthy older adults had asymmetry in knee extensor strength (6%, p < 0.05) comparable to that found in patients, but had no asymmetry in leg extensor power. Patients had generalized weakening of the affected lower extremity and numerically the largest asymmetry was evident for leg extensor power. In contrast, healthy peers had no asymmetry in leg extensor power. These results indicate that exercise interventions focusing on improving leg extensor power of the symptomatic lower extremity and reducing asymmetry may be beneficial for patients with hip osteoarthritis. Implications for Rehabilitation Even in patients with mild symptoms not awaiting hip replacement a generalized muscle weakening of the symptomatic lower extremity seems to be present. Between-leg differences in leg extensor power (force × velocity) appears to be relatively large (19%) in patients with unilateral hip osteoarthritis in contrast to healthy peers who show no asymmetry. Compared to muscle strength the relationship between functional performance and leg extensor power seems to be stronger, and more strongly related to power of the symptomatic lower extremity. Our results indicate that exercise interventions focusing on improving leg extensor power of the symptomatic lower extremity and reducing asymmetry may be beneficial for patients with mild symptoms not awaiting hip replacement.

Hydrotherapy improves pain and function in older women with knee osteoarthritis: a randomized controlled trial.

PubMed

Dias, João Marcos; Cisneros, Lígia; Dias, Rosângela; Fritsch, Carolina; Gomes, Wellington; Pereira, Leani; Santos, Mary Luci; Ferreira, Paulo Henrique

Currently, there is poor evidence of the effect of hydrotherapy alone on patients with hip or knee osteoarthritis. The study aimed to assess the impact of hydrotherapy on pain, function, and muscle function in older women with knee osteoarthritis. A randomized controlled trial was conducted to evaluate the efficacy of hydrotherapy in women with knee osteoarthritis. Seventy-three women aged 65 and older were randomized to hydrotherapy (n=36) or a control group (n=37). The hydrotherapy group received the intervention program in a heated pool (twice per week for six weeks) and an educational protocol while the control group received an educational protocol only. Primary outcomes (before and post-treatment) were pain intensity (0-100) and function (0-100), assessed with the WOMAC questionnaire. Secondary outcomes (before and post-treatment) were knee extensor and knee flexor muscle performance (strength, power, and endurance), assessed by an isokinetic dynamometer. The magnitude of change between the groups for the outcomes was calculated using linear regression models adjusted by baseline outcome values. The hydrotherapy group had better outcomes for pain (adjusted mean difference=11 points, 95% CI: 3-18) and function (adjusted mean difference=12 points, 95% CI: 5-18). Patients receiving hydrotherapy had better performance for knee flexor and extensor strength, knee flexor power, and knee extensor endurance. Older women with knee osteoarthritis are likely to have benefits from a course of hydrotherapy exercises. Registry of clinical trials (Trial number RBR-8F57KR) - http://www.ensaiosclinicos.gov.br/rg/RBR-8f57kr/. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

Effects of Progressive Resistance Strength Training on Knee Biomechanics During Single Leg Step-up in Persons with Mild Knee Osteoarthritis

PubMed Central

McQuade, Kevin James; de Oliveira, Anamaria Siriani

2011-01-01

Background The goal of this study was to determine if increasing strength in primary knee extensors and flexors would directly affect net knee joint moments during a common functional task in persons with knee osteoarthritis. Methods An exploratory single sample clinical trial with pre-post treatment measures was used to study volunteers with clinical diagnosis of mild knee OA in one knee. Subjects participated in an individually supervised training program 3 times a week for eight weeks consisting of progressive resistive exercises for knee extensors and knee flexors. Pre and post training outcome assessments included: 1. Net internal knee joint moments, 2. Electromyography of primary knee extensors and flexors, and 3. Self-report measures of knee pain and function. The distribution of lower extremity joint moments as a percent of the total support moment was also investigated. Findings Pain, symptoms, activities of daily life, quality of life, stiffness, and function scores showed significant improvement following strength training. Knee internal valgus and hip internal rotation moments showed increasing but non-statistically significant changes post-training. There were no significant differences in muscle co-contraction activation of the Quadriceps and Hamstrings. Interpretations While exercise continues to be an important element of OA management, the results of this study suggest improvements in function, pain, and other symptoms, as a result of strength training may not be causally related to specific biomechanical changes in net joint moments. PMID:21514018

Lower-volume muscle-damaging exercise protects against high-volume muscle-damaging exercise and the detrimental effects on endurance performance.

PubMed

Burt, Dean; Lamb, Kevin; Nicholas, Ceri; Twist, Craig

2015-07-01

This study examined whether lower-volume exercise-induced muscle damage (EIMD) performed 2 weeks before high-volume muscle-damaging exercise protects against its detrimental effect on running performance. Sixteen male participants were randomly assigned to a lower-volume (five sets of ten squats, n = 8) or high-volume (ten sets of ten squats, n = 8) EIMD group and completed baseline measurements for muscle soreness, knee extensor torque, creatine kinase (CK), a 5-min fixed-intensity running bout and a 3-km running time-trial. Measurements were repeated 24 and 48 h after EIMD, and the running time-trial after 48 h. Two weeks later, both groups repeated the baseline measurements, ten sets of ten squats and the same follow-up testing (Bout 2). Data analysis revealed increases in muscle soreness and CK and decreases in knee extensor torque 24-48 h after the initial bouts of EIMD. Increases in oxygen uptake [Formula: see text], minute ventilation [Formula: see text] and rating of perceived exertion were observed during fixed-intensity running 24-48 h after EIMD Bout 1. Likewise, time increased and speed and [Formula: see text] decreased during a 3-km running time-trial 48 h after EIMD. Symptoms of EIMD, responses during fixed-intensity and running time-trial were attenuated in the days after the repeated bout of high-volume EIMD performed 2 weeks after the initial bout. This study demonstrates that the protective effect of lower-volume EIMD on subsequent high-volume EIMD is transferable to endurance running. Furthermore, time-trial performance was found to be preserved after a repeated bout of EIMD.

The effects of low-repetition and light-load power training on bone mineral density in postmenopausal women with sarcopenia: a pilot study.

PubMed

Hamaguchi, Kanako; Kurihara, Toshiyuki; Fujimoto, Masahiro; Iemitsu, Motoyuki; Sato, Koji; Hamaoka, Takafumi; Sanada, Kiyoshi

2017-05-02

Age-related reduction in bone mineral density (BMD) is generally accelerated in women after menopause, and could be even more pronounced in individuals with sarcopenia. Light-load power training with a low number of repetitions would increase BMD, significantly reducing bone loss in individuals at risk of osteoporosis. This study investigated the effects of low-repetition, light-load power training on BMD in Japanese postmenopausal women with sarcopenia. The training group (n = 7) followed a progressive power training protocol that increased the load with a weighted vest, for two sessions per week, over the course of 6 weeks. The training exercise comprised five kinds of exercises (squats, front lunges, side lunges, calf raises, and toe raises), and each exercise contained eight sets of three repetitions with a 15-s rest between each set. The control group (n = 8) did not undergo any training intervention. We measured BMD, muscle strength, and anthropometric data. Within-group changes in pelvis BMD and knee extensor strength were significantly greater in the training group than the control group (p = 0.029 and 0.030 for pelvis BMD and knee extensor strength, respectively). After low-repetition, light-load power training, we noted improvements in pelvis BMD (1.6%) and knee extensor strength (15.5%). No significant within- or between-group differences were observed for anthropometric data or forearm BMD. Six weeks of low-repetition, light-load power training improved pelvis BMD and knee extensor strength in postmenopausal women with sarcopenia. Since this training program does not require high-load exercise and is therefore easily implementable as daily exercise, it could be an effective form of exercise for sedentary adults at risk for osteoporosis who are fearful of heavy loads and/or training that could cause fatigue. This trial was registered with the University Hospital Medical Information Network on 31 October 2016 ( UMIN000024651 ).

The effects of two different frequencies of whole-body vibration on knee extensors strength in healthy young volunteers: a randomized trial

PubMed Central

Esmaeilzadeh, S.; Akpinar, M.; Polat, S.; Yildiz, A.; Oral, A.

2015-01-01

The aim of this study was to investigate the effects of two different frequencies of whole-body vibration (WBV) training on knee extensors muscle strength in healthy young volunteers. Twenty-two eligible healthy untrained young women aged 22-31 years were allocated randomly to the 30-Hz (n=11) and 50-Hz (n=11) groups. They participated in a supervised WBV training program that consisted of 24 sessions on a synchronous vertical vibration platform (peak-to-peak displacement: 2-4 mm; type of exercises: semi-squat, one-legged squat, and lunge positions on right leg; set numbers: 2-24) three times per week for 8 weeks. Isometric and dynamic strength of the knee extensors were measured prior to and at the end of the 8-week training. In the 30-Hz group, there was a significant increase in the maximal voluntary isometric contraction (p=0.039) and the concentric peak torque (p=0.018) of knee extensors and these changes were significant (p<0.05) compared with the 50-Hz group. In addition, the eccentric peak torque of knee extensors was increased significantly in both groups (p<0.05); however, there was no significant difference between the two groups (p=0.873). We concluded that 8 weeks WBV training in 30 Hz was more effective than 50 Hz to increase the isometric contraction and dynamic strength of knee extensors as measured using peak concentric torque and equally effective with 50 Hz in improving eccentric torque of knee extensors in healthy young untrained women. PMID:26636279

Electromyographic analyses of muscle pre-activation induced by single joint exercise.

PubMed

Júnior, Valdinar A R; Bottaro, Martim; Pereira, Maria C C; Andrade, Marcelino M; P Júnior, Paulo R W; Carmo, Jake C

2010-01-01

To investigate whether performing a low-intensity, single-joint exercises for knee extensors was an efficient strategy for increasing the number of motor units recruited in the vastus lateralis muscle during a subsequent multi-joint exercises. Nine healthy male participants (23.33+/-3.46 yrs) underwent bouts of exercise in which knee extension and 45 degrees , and leg press exercises were performed in sequence. In the low-intensity bout (R30), 15 unilateral knee extensions were performed, followed by 15 repetitions of the leg presses at 30% and 60% of one maximum repetition load (1-MR), respectively. In the high-intensity bout (R60), the same sequence was performed, but the applied load was 60% of 1-MR for both exercises. A single set of 15 repetitions of the leg press at 60% of 1-MR was performed as a control exercise (CR). The surface electromyographic signals of the vastus lateralis muscle were recorded by means of a linear electrode array. The root mean square (RMS) values were determined for each repetition of the leg press, and linear regressions were calculated from these results. The slopes of the straight lines obtained were then normalized using the linear coefficients of the regression equations and compared using one-way ANOVAs for repeated measures. The slopes observed in the CR were significantly lower than those in the R30 and R60 (p<0.05). The results indicated that the recruitment of motor units was more effective when a single-joint exercise preceded the multi-joint exercise. Article registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) under the number ACTRN12609000413224.

Walking and Running Require Greater Effort from the Ankle than the Knee Extensor Muscles.

PubMed

Kulmala, Juha-Pekka; Korhonen, Marko T; Ruggiero, Luca; Kuitunen, Sami; Suominen, Harri; Heinonen, Ari; Mikkola, Aki; Avela, Janne

2016-11-01

The knee and ankle extensors as human primary antigravity muscle groups are of utmost importance in a wide range of locomotor activities. Yet, we know surprisingly little about how these muscle groups work, and specifically, how close to their maximal capacities they function across different modes and intensity of locomotion. Therefore, to advance our understanding of locomotor constraints, we determined and compared relative operating efforts of the knee and ankle extensors during walking, running, and sprinting. Using an inverse dynamics biomechanical analysis, the muscle forces of the knee and ankle extensors during walking (1.6 m·s), running (4.1 m·s), and sprinting (9.3 m·s) were quantified and then related to maximum forces of the same muscle groups obtained from a reference hopping test that permitted natural elastic limb behavior. During walking, the relative effort of the ankle extensors was almost two times greater compared with the knee extensors (35% ± 6% vs 19% ± 5%, P < 0.001). Changing walking to running decreased the difference in the relative effort between the extensor muscle groups, but still, the ankle extensors operated at a 25% greater level than the knee extensors (84% ± 12% vs 63% ± 17%, P < 0.05). At top speed sprinting, the ankle extensors reached their maximum operating level, whereas the knee extensors still worked well below their limits, showing a 25% lower relative effort compared with the ankle extensors (96% ± 11% vs 72% ± 19%, P < 0.01). Regardless of the mode of locomotion, humans operate at a much greater relative effort at the ankle than knee extensor muscles. As a consequence, the great demand on ankle extensors may be a key biomechanical factor limiting our locomotor ability and influencing the way we locomote and adapt to accommodate compromised neuromuscular system function.

The influence of caffeine ingestion on strength and power performance in female team-sport players.

PubMed

Ali, Ajmol; O'Donnell, Jemma; Foskett, Andrew; Rutherfurd-Markwick, Kay

2016-01-01

The aim of this study was to examine the influence of caffeine supplementation on knee flexor and knee extensor strength before, during and after intermittent running exercise in female team-sport players taking oral contraceptive steroids (OCS). Ten healthy females (24 ± 4 years; 59.7 ± 3.5 kg; undertaking 2-6 training sessions per week) taking low-dose monophasic oral contraceptives of the same hormonal composition took part in a randomised, double-blind, placebo-controlled crossover-design trial. Sixty minutes following the ingestion of a capsule containing 6 mg∙kg -1 body mass anhydrous caffeine or artificial sweetener (placebo), participants completed a 90-min intermittent treadmill-running protocol. Isometric strength performance and eccentric and concentric strength and power of the knee flexors and knee extensors (using isokinetic dynamometer), as well as countermovement jump (CMJ), was measured before, during and after the exercise protocol, as well as ~12 h post-exercise. Blood samples were taken before, during and post-exercise to measure glucose, insulin and free fatty acids (FFA). Caffeine supplementation significantly increased eccentric strength of the knee flexors ( P  < 0.05) and eccentric power of both the knee flexors ( P  < 0.05) and extensors ( P  < 0.05). However, there was no effect on isometric or concentric parameters, or CMJ performance. FFA was elevated with caffeine supplementation over time ( P  < 0.05) while levels of glucose and insulin were not affected by caffeine intake. Caffeine supplementation increased eccentric strength and power in female team-sport players taking OCS both during an intermittent running protocol and the following morning.

The effect of an intensive exercise programme on leg function in chronic stroke patients: a pilot study with one-year follow-up.

PubMed

Stock, Roland; Mork, Paul Jarle

2009-09-01

To investigate the effect of two weeks of intensive exercise on leg function in chronic stroke patients and to evaluate the feasibility of an intensive exercise programme in a group setting. Pilot study with one-group pre-test post-test design with two pre-tests and one-year follow-up. Inpatient rehabilitation hospital. Twelve hemiparetic patients completed the intervention. Ten patients participated at one-year follow-up. Six hours of daily intensive exercise for two weeks with focus on weight-shifting towards the affected side and increased use of the affected extremity during functional activities. An insole with nubs in the shoe of the non-paretic limb was used to reinforce weight-shift toward the affected side. Timed Up and Go, Four Square Step Test, gait velocity, gait symmetry and muscle strength in knee and ankle muscles. Maximal gait velocity (P = 0.002) and performance time (seconds) on Timed Up and Go (mean, SD; 12.2, 3.8 vs. 9.4, 3.2) and Four Square Step Test improved from pre- to post-test (P = 0.005). Improvements remained significant at follow-up. Preferred gait velocity and gait symmetry remained unchanged. Knee extensor (P<50.009) and flexor (P<50.001) strength increased bilaterally from pre- to post-test but only knee flexor strength remained significant at follow-up. Ankle dorsi flexor (P = 0.02) and plantar flexor (P<0.001) strength increased on paretic side only (not tested at follow-up). Intensive exercise for lower extremity is feasible in a group setting and was effective in improving ambulatory function, maximal gait velocity and muscle strength in chronic stroke patients. Most improvements persisted at the one-year follow-up.

Muscle performance following an acute bout of plyometric training combined with low or high intensity weight exercise.

PubMed

Beneka, Anastasia G; Malliou, Paraskevi K; Missailidou, Victoria; Chatzinikolaou, Athanasios; Fatouros, Ioannis; Gourgoulis, Vassilios; Georgiadis, Elias

2013-01-01

To determine the time course of performance responses after an acute bout of plyometric exercise combined with high and low intensity weight training, a 3-group (including a control group), repeated-measures design was employed. Changes in performance were monitored through jumping ability by measuring countermovement and squat jumping, and strength performance assessment through isometric and isokinetic testing of knee extensors (at two different velocities). Participants in both experimental groups performed a plyometric protocol consisting of 50 jumps over 50 cm hurdles and 50 drop jumps from a 50 cm plyometric box. Additionally, each group performed two basic weight exercises consisting of leg presses and leg extensions at 90-95% of maximum muscle strength for the high intensity group and 60% of maximum muscle strength for the low intensity group. The results of the study suggest that an acute bout of intense plyometric exercise combined with weight exercise induces time-dependent changes in performance, which are also dependent on the nature of exercise protocol and testing procedures. In conclusion, acute plyometric exercise with weight exercise may induce a substantial decline in jumping performance for as long as 72 hours but not in other forms of muscle strength.

Exergaming with a pediatric exoskeleton: Facilitating rehabilitation and research in children with cerebral palsy.

PubMed

Bulea, Thomas C; Lerner, Zachary F; Gravunder, Andrew J; Damiano, Diane L

2017-07-01

Effective rehabilitation of children with cerebral palsy (CP) requires intensive task-specific exercise but many in this population lack the motor capabilities to complete the desired training tasks. Providing robotic assistance is a potential solution yet the effects of this assistance are unclear. We combined a novel exoskeleton and exercise video game (exergame) to create a new rehabilitation paradigm for children with CP. We incorporated high density electroencephalography (EEG) to assess cortical activity. Movement to targets in the game was controlled by knee extension while standing. The distance between targets was the same with and without the exoskeleton to isolate the effect of robotic assistance. Our results show that children with CP maintain or increase knee extensor muscle activity during knee extension in the presence of synergistic robotic assistance. Our EEG findings also demonstrate that participants remained engaged in the exercise with robotic assistance. Interestingly we observed a developmental trajectory of sensorimotor mu rhythm in children with CP similar, though delayed, to those reported in typically developing children. While not the goal here, the exoskeleton significantly increased knee extension in 3/6 participants during use. Future work will focus on utilizing the exoskeleton to enhance volitional knee extension capability and in combination with EMG and EEG to study sensorimotor cortex response to progressive exercise in children with CP.

Neuromuscular fatigue following constant versus variable-intensity endurance cycling in triathletes.

PubMed

Lepers, R; Theurel, J; Hausswirth, C; Bernard, T

2008-07-01

The aim of this study was to determine whether or not variable power cycling produced greater neuromuscular fatigue of knee extensor muscles than constant power cycling at the same mean power output. Eight male triathletes (age: 33+/-5 years, mass: 74+/-4 kg, VO2max: 62+/-5 mL kg(-1) min(-1), maximal aerobic power: 392+/-17 W) performed two 30 min trials on a cycle ergometer in a random order. Cycling exercise was performed either at a constant power output (CP) corresponding to 75% of the maximal aerobic power (MAP) or a variable power output (VP) with alternating +/-15%, +/-5%, and +/-10% of 75% MAP approximately every 5 min. Maximal voluntary contraction (MVC) torque, maximal voluntary activation level and excitation-contraction coupling process of knee extensor muscles were evaluated before and immediately after the exercise using the technique of electrically evoked contractions (single and paired stimulations). Oxygen uptake, ventilation and heart rate were also measured at regular intervals during the exercise. Averaged metabolic variables were not significantly different between the two conditions. Similarly, reductions in MVC torque (approximately -11%, P<0.05) after cycling were not different (P>0.05) between CP and VP trials. The magnitude of central and peripheral fatigue was also similar at the end of the two cycling exercises. It is concluded that, following 30 min of endurance cycling, semi-elite triathletes experienced no additional neuromuscular fatigue by varying power (from +/-5% to 15%) compared with a protocol that involved a constant power.

Dietary and performance assessment of elite soccer players during a period of intense training.

PubMed

Rico-Sanz, J; Frontera, W R; Molé, P A; Rivera, M A; Rivera-Brown, A; Meredith, C N

1998-09-01

This study examined the nutritional and performance status of elite soccer players during intense training. Eight male players (age 17+/-2 years) of the Puerto Rican Olympic Team recorded daily activities and food intake over 12 days. Daily energy expenditure was 3,833+/-571 (SD) kcal, and energy intake was 3,952+/-1,071 kcal, of which 53.2+/-6.2% (8.3 g x kg BW(-1)) was from carbohydrates (CHO), 32.4+/-4.0% from fat, and 14.4+/-2.3% from protein. With the exception of calcium, all micronutrients examined were in accordance with dietary guidelines. Body fat was 7.6+/-1.1% of body weight. Time to completion of three runs of the soccer-specific test was 37.65+/-0.62 s, and peak torques of the knee flexors and extensors at 60 degrees x s(-1) were 139+/-6 and 225+/-9 N x m, respectively. Players' absolute amounts of CHO seemed to be above the minimum recommended intake to maximize glycogen storage, but calcium intakes were below recommended. Their body fat was unremarkable, and they had a comparatively good capacity to endure repeated bouts of intense soccer-specific exercise and to exert force with their knee extensors and flexors.

Net joint moments and muscle activation in barbell squats without and with restricted anterior leg rotation.

PubMed

Chiu, Loren Z F; vonGaza, Gabriella L; Jean, Liane M Y

2017-01-01

Muscle utilisation in squat exercise depends on technique. The purpose of this study was to compare net joint moments (NJMs) and muscle activation during squats without and with restricted leg dorsiflexion. Experienced men (n = 5) and women (n = 4) performed full squats at 80% one repetition maximum. 3D motion analysis, force platform and (EMG) data were collected. Restricting anterior leg rotation reduced anterior leg (P = 0.001) and posterior thigh (P < 0.001) rotations, resulting in a smaller knee flexion range of motion (P < 0.001). At maximum squat depth, ankle plantar flexor (P < 0.001) and knee extensor (P < 0.001) NJM were higher in unrestricted squats. Hip extensor NJM (P = 0.14) was not different between squat types at maximum squat depth. Vastus lateralis (P > 0.05), vastus medialis (P > 0.05) and rectus femoris (P > 0.05) EMG were not different between squat types. Unrestricted squats have higher ankle plantar flexor and knee extensor NJM than previously reported from jumping and landing. However, ankle plantar flexor and knee extensor NJM are lower in restricted squats than previous studies of jumping and landing. The high NJM in unrestricted squat exercise performed through a full range of motion suggests this squat type would be more effective to stimulate adaptations in the lower extremity musculature than restricted squats.

Effect of Exercise-Induced Enhancement of the Leg-Extensor Muscle-Tendon Unit Capacities on Ambulatory Mechanics and Knee Osteoarthritis Markers in the Elderly

PubMed Central

Karamanidis, Kiros; Oberländer, Kai Daniel; Niehoff, Anja; Epro, Gaspar; Brüggemann, Gert-Peter

2014-01-01

Objective Leg-extensor muscle weakness could be a key component in knee joint degeneration in the elderly because it may result in altered muscular control during locomotion influencing the mechanical environment within the joint. This work aimed to examine whether an exercise-induced enhancement of the triceps surae (TS) and quadriceps femoris (QF) muscle-tendon unit (MTU) capacities would affect mechanical and biological markers for knee osteoarthritis in the elderly. Methods Twelve older women completed a 14-week TS and QF MTU exercise intervention, which had already been established as increasing muscle strength and tendon stiffness. Locomotion mechanics and serum cartilage oligomeric matrix protein (COMP) levels were examined during incline walking. MTU mechanical properties were assessed using simultaneously ultrasonography and dynamometry. Results Post exercise intervention, the elderly had higher TS and QF contractile strength and tendon-aponeurosis stiffness. Regarding the incline gait task, the subjects demonstrated a lower external knee adduction moment and lower knee adduction angular impulse during the stance phase post-intervention. Furthermore, post-intervention compared to pre-intervention, the elderly showed lower external hip adduction moment, but revealed higher plantarflexion pushoff moment. The changes in the external knee adduction moment were significantly correlated with the improvement in ankle pushoff function. Serum COMP concentration increased in response to the 0.5-h incline walking exercise with no differences in the magnitude of increment between pre- and post-intervention. Conclusions This work emphasizes the important role played by the ankle pushoff function in knee joint mechanical loading during locomotion, and may justify the inclusion of the TS MTU in prevention programs aiming to positively influence specific mechanical markers for knee osteoarthritis in the elderly. However, the study was unable to show that COMP is amenable to change in the elderly following a 14-week exercise intervention and, therefore, the physiological benefit of improved muscle function for knee cartilage requires further investigation. PMID:24905024

Effect of exercise-induced enhancement of the leg-extensor muscle-tendon unit capacities on ambulatory mechanics and knee osteoarthritis markers in the elderly.

PubMed

Karamanidis, Kiros; Oberländer, Kai Daniel; Niehoff, Anja; Epro, Gaspar; Brüggemann, Gert-Peter

2014-01-01

Leg-extensor muscle weakness could be a key component in knee joint degeneration in the elderly because it may result in altered muscular control during locomotion influencing the mechanical environment within the joint. This work aimed to examine whether an exercise-induced enhancement of the triceps surae (TS) and quadriceps femoris (QF) muscle-tendon unit (MTU) capacities would affect mechanical and biological markers for knee osteoarthritis in the elderly. Twelve older women completed a 14-week TS and QF MTU exercise intervention, which had already been established as increasing muscle strength and tendon stiffness. Locomotion mechanics and serum cartilage oligomeric matrix protein (COMP) levels were examined during incline walking. MTU mechanical properties were assessed using simultaneously ultrasonography and dynamometry. Post exercise intervention, the elderly had higher TS and QF contractile strength and tendon-aponeurosis stiffness. Regarding the incline gait task, the subjects demonstrated a lower external knee adduction moment and lower knee adduction angular impulse during the stance phase post-intervention. Furthermore, post-intervention compared to pre-intervention, the elderly showed lower external hip adduction moment, but revealed higher plantarflexion pushoff moment. The changes in the external knee adduction moment were significantly correlated with the improvement in ankle pushoff function. Serum COMP concentration increased in response to the 0.5-h incline walking exercise with no differences in the magnitude of increment between pre- and post-intervention. This work emphasizes the important role played by the ankle pushoff function in knee joint mechanical loading during locomotion, and may justify the inclusion of the TS MTU in prevention programs aiming to positively influence specific mechanical markers for knee osteoarthritis in the elderly. However, the study was unable to show that COMP is amenable to change in the elderly following a 14-week exercise intervention and, therefore, the physiological benefit of improved muscle function for knee cartilage requires further investigation.

Dehydration reduces left ventricular filling at rest and during exercise independent of twist mechanics.

PubMed

Stöhr, Eric J; González-Alonso, José; Pearson, James; Low, David A; Ali, Leena; Barker, Horace; Shave, Rob

2011-09-01

The purpose of this study was to determine whether the reduction in stroke volume (SV), previously shown to occur with dehydration and increases in internal body temperatures during prolonged exercise, is caused by a reduction in left ventricular (LV) function, as indicated by LV volumes, strain, and twist ("LV mechanics"). Eight healthy men [age: 20 ± 2, maximal oxygen uptake (VO₂max): 58 ± 7 ml·kg⁻¹·min⁻¹] completed two, 1-h bouts of cycling in the heat (35°C, 50% peak power) without fluid replacement, resulting in 2% and 3.5% dehydration, respectively. Conventional and two-dimensional speckle-tracking echocardiography was used to determine LV volumes, strain, and twist at rest and during one-legged knee-extensor exercise at baseline, both levels of dehydration, and following rehydration. Progressive dehydration caused a significant reduction in end-diastolic volume (EDV) and SV at rest and during one-legged knee-extensor exercise (rest: Δ-33 ± 14 and Δ-21 ± 14 ml, respectively; exercise: Δ-30 ± 10 and Δ-22 ± 9 ml, respectively, during 3.5% dehydration). In contrast to the marked decline in EDV and SV, systolic and diastolic LV mechanics were either maintained or even enhanced with dehydration at rest and during knee-extensor exercise. We conclude that dehydration-induced reductions in SV at rest and during exercise are the result of reduced LV filling, as reflected by the decline in EDV. The concomitant maintenance of LV mechanics suggests that the decrease in LV filling, and consequently ejection, is likely caused by the reduction in blood volume and/or diminished filling time rather than impaired LV function.

Side Differences of Thigh Muscle Cross-Sectional Areas and Maximal Isometric Muscle Force in Bilateral Knees with the Same Radiographic Disease Stage, but Unilateral Frequent Pain – Data from the Osteoarthritis Initiative

PubMed Central

Sattler, Martina; Dannhauer, Torben; Hudelmaier, Martin; Wirth, Wolfgang; Sänger, Alexandra M.; Kwoh, C. Kent; Hunter, David J.; Eckstein, Felix

2012-01-01

Objective To determine whether anatomical thigh muscle cross-sectional areas (MCSAs) and strength differ between osteoarthritis (OA) knees with frequent pain compared with contralateral knees without pain, and to examine the correlation between MCSAs and strength in painful versus painless knees. Methods 48 subjects (31 women; 17 men; age 45–78 years) were drawn from 4796 Osteoarthritis Initiative (OAI) participants, in whom both knees displayed the same radiographic stage (KLG2 or 3), one with frequent pain (most days of the month within the past 12 months) and the contralateral one without pain. Axial MR images were used to determine MCSAs of extensors, flexors and adductors at 35% femoral length (distal to proximal) and in two adjacent 5 mm images. Maximal isometric extensor and flexor forces were used as provided from the OAI data base. Results Painful knees showed 5.2% lower extensor MCSAs (p=0.00003; paired t-test), and 7.8% lower maximal extensor muscle forces (p=0.003) than contra-lateral painless knees. There were no significant differences in flexor forces, or flexor and adductor MCSAs (p>0.39). Correlations between force and MCSAs were similar in painful and painless OA knees (0.44

Are Females More Resistant to Extreme Neuromuscular Fatigue?

PubMed

Temesi, John; Arnal, Pierrick J; Rupp, Thomas; Féasson, Léonard; Cartier, Régine; Gergelé, Laurent; Verges, Samuel; Martin, Vincent; Millet, Guillaume Y

2015-07-01

Despite interest in the possibility of females outperforming males in ultraendurance sporting events, little is known about the sex differences in fatigue during prolonged locomotor exercise. This study investigated possible sex differences in central and peripheral fatigue in the knee extensors and plantar flexors resulting from a 110-km ultra-trail-running race. Neuromuscular function of the knee extensors and plantar flexors was evaluated via transcranial magnetic stimulation (TMS) and electrical nerve stimulation before and after an ultra-trail-running race in 20 experienced ultraendurance trail runners (10 females and 10 males matched by percent of the winning time by sex) during maximal and submaximal voluntary contractions and in relaxed muscle. Maximal voluntary knee extensor torque decreased more in males than in females (-38% vs -29%, P = 0.006) although the reduction in plantar flexor torque was similar between sexes (-26% vs -31%). Evoked mechanical plantar flexor responses decreased more in males than in females (-23% vs -8% for potentiated twitch amplitude, P = 0.010), indicating greater plantar flexor peripheral fatigue in males. Maximal voluntary activation assessed by TMS and electrical nerve stimulation decreased similarly in both sexes for both muscle groups. Indices of knee extensor peripheral fatigue and corticospinal excitability and inhibition changes were also similar for both sexes. Females exhibited less peripheral fatigue in the plantar flexors than males did after a 110-km ultra-trail-running race and males demonstrated a greater decrease in maximal force loss in the knee extensors. There were no differences in the magnitude of central fatigue for either muscle group or TMS-induced outcomes. The lower level of fatigue in the knee extensors and peripheral fatigue in the plantar flexors could partly explain the reports of better performance in females in extreme duration running races as race distance increases.

Elbow flexor fatigue modulates central excitability of the knee extensors.

PubMed

Aboodarda, Saied Jalal; Copithorne, David B; Power, Kevin E; Drinkwater, Eric; Behm, David G

2015-09-01

The present study investigated the effects of exercise-induced elbow flexor fatigue on voluntary force output, electromyographic (EMG) activity and motoneurone excitability of the nonexercised knee extensor muscles. Eleven participants attended 3 testing sessions: (i) control, (ii) unilateral fatiguing elbow flexion and (iii) bilateral fatiguing elbow flexion (BiFlex). The nonfatigued knee extensor muscles were assessed with thoracic motor evoked potentials (TMEPs), maximal compound muscle action potential (Mmax), knee extensor maximal voluntary contractions (MVCs), and normalized EMG activity before and at 30 s, 3 min, and 5 min postexercise. BiFlex showed significantly lower (Δ = -18%, p = 0.03) vastus lateralis (VL) normalized EMG activity compared with the control session whereas knee extension MVC force did not show any statistical difference between the 3 conditions (p = 0.12). The TMEP·Mmax(-1) ratio measured at the VL showed a significantly higher value (Δ = +46%, p = 0.003) following BiFlex compared with the control condition at 30 s postexercise. The results suggest that the lower VL normalized EMG following BiFlex might have been due to a reduction in supraspinal motor output because spinal motoneuronal responses demonstrated substantially higher value (30 s postexercise) and peripheral excitability (compound muscle action potential) showed no change following BiFelex than control condition.

Effects of training and weight support on muscle activation in Parkinson's disease.

PubMed

Rose, Martin H; Løkkegaard, Annemette; Sonne-Holm, Stig; Jensen, Bente R

2013-12-01

The aim of this study was to investigate the effect of high-intensity locomotor training on knee extensor and flexor muscle activation and adaptability to increased body-weight (BW) support during walking in patients with Parkinson's disease (PD). Thirteen male patients with idiopathic PD and eight healthy participants were included. The PD patients completed an 8-week training program on a lower-body, positive-pressure treadmill. Knee extensor and flexor muscles activation during steady treadmill walking (3 km/h) were measured before, at the mid-point, and after training. Increasing BW support decreased knee extensor muscle activation (normalization) and increased knee flexor muscle activation (abnormal) in PD patients when compared to healthy participants. Training improved flexor peak muscle activation adaptability to increased (BW) support during walking in PD patients. During walking without BW support shorter knee extensor muscle off-activation time and increased relative peak muscle activation was observed in PD patients and did not improve with 8 weeks of training. In conclusion, patients with PD walked with excessive activation of the knee extensor and flexor muscles when compared to healthy participants. Specialized locomotor training may facilitate adaptive processes related to motor control of walking in PD patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

Inhibition of α-adrenergic vasoconstriction in exercising human thigh muscles

PubMed Central

Wray, D Walter; Fadel, Paul J; Smith, Michael L; Raven, Peter; Sander, Mikael

2004-01-01

The mechanisms underlying metabolic inhibition of sympathetic responses within exercising skeletal muscle remain incompletely understood. The aim of the present study was to test whether α2-adrenoreceptor-mediated vasoconstriction was more sensitive to metabolic inhibition than α1-vasoconstriction during dynamic knee-extensor exercise. We studied healthy volunteers using two protocols: (1) wide dose ranges of the α-adrenoreceptor agonists phenylephrine (PE, α1 selective) and BHT-933 (BHT, α2 selective) were administered intra-arterially at rest and during 27 W knee-extensor exercise (n = 13); (2) flow-adjusted doses of PE (0.3 μg kg−1 l−1) and BHT (15 μg kg−1 l−1) were administered at rest and during ramped exercise (7 W to 37 W; n= 10). Ultrasound Doppler and thermodilution techniques provided direct measurements of femoral blood flow (FBF). PE (0.8 μg kg−1) and BHT (40 μg kg−1) produced comparable maximal reductions in FBF at rest (−58 ± 6 versus−64 ± 4%). Despite increasing the doses, PE (1.6 μg kg−1 min−1) and BHT (80 μg kg−1 min−1) caused significantly smaller changes in FBF during 27 W exercise (−13 ± 4 versus−3 ± 5%). During ramped exercise, significant vasoconstriction at lower intensities (7 and 17 W) was seen following PE (−16 ± 5 and −16 ± 4%), but not BHT (−2 ± 4 and −4 ± 5%). At the highest intensity (37 W), FBF was not significantly changed by either drug. Collectively, these data demonstrate metabolic inhibition of α-adrenergic vasoconstriction in large postural muscles of healthy humans. Both α1- and α2-adrenoreceptor agonists produce comparable vasoconstriction in the resting leg, and dynamic thigh exercise attenuates α1- and α2-mediated vasoconstriction similarly. However, α2-mediated vasoconstriction appears more sensitive to metabolic inhibition, because α2 is completely inhibited even at low workloads, whereas α1 becomes progressively inhibited with increasing workloads. PMID:14694145

Whole-body heat stress and exercise stimulate the appearance of platelet microvesicles in plasma with limited influence of vascular shear stress.

PubMed

Wilhelm, Eurico N; González-Alonso, José; Chiesa, Scott T; Trangmar, Steven J; Kalsi, Kameljit K; Rakobowchuk, Mark

2017-11-01

Intense, large muscle mass exercise increases circulating microvesicles, but our understanding of microvesicle dynamics and mechanisms inducing their release remains limited. However, increased vascular shear stress is generally thought to be involved. Here, we manipulated exercise-independent and exercise-dependent shear stress using systemic heat stress with localized single-leg cooling (low shear) followed by single-leg knee extensor exercise with the cooled or heated leg (Study 1, n  = 8) and whole-body passive heat stress followed by cycling (Study 2, n  = 8). We quantified femoral artery shear rates (SRs) and arterial and venous platelet microvesicles (PMV-CD41 + ) and endothelial microvesicles (EMV-CD62E + ). In Study 1, mild passive heat stress while one leg remained cooled did not affect [microvesicle] ( P  ≥ 0.05). Single-leg knee extensor exercise increased active leg SRs by ~12-fold and increased arterial and venous [PMVs] by two- to threefold, even in the nonexercising contralateral leg ( P  < 0.05). In Study 2, moderate whole-body passive heat stress increased arterial [PMV] compared with baseline (mean±SE, from 19.9 ± 1.5 to 35.5 ± 5.4 PMV . μ L -1. 10 3 , P  < 0.05), and cycling with heat stress increased [PMV] further in the venous circulation (from 27.5 ± 2.2 at baseline to 57.5 ± 7.2 PMV . μ L -1. 10 3 during cycling with heat stress, P  < 0.05), with a tendency for increased appearance of PMV across exercising limbs. Taken together, these findings demonstrate that whole-body heat stress may increase arterial [PMV], and intense exercise engaging either large or small muscle mass promote PMV formation locally and systemically, with no influence upon [EMV]. Local shear stress, however, does not appear to be the major stimulus modulating PMV formation in healthy humans. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Exercise training, but not resveratrol, improves metabolic and inflammatory status in skeletal muscle of aged men

PubMed Central

Olesen, Jesper; Gliemann, Lasse; Biensø, Rasmus; Schmidt, Jakob; Hellsten, Ylva; Pilegaard, Henriette

2014-01-01

The aim was to investigate the metabolic and anti-inflammatory effects of resveratrol alone and when combined with exercise training in skeletal muscle of aged human subjects. Healthy, physically inactive men (60–72 years old) were randomized to either 8 weeks of daily intake of 250 mg resveratrol or placebo or to 8 weeks of high-intensity exercise training with 250 mg resveratrol or placebo. Before and after the interventions, resting blood samples and muscle biopsies were obtained and a one-legged knee-extensor endurance exercise test was performed. Exercise training increased skeletal muscle peroxisome proliferator-activated receptor-γ co-activator-1α mRNA ∼1.5-fold, cytochrome c protein ∼1.3-fold, cytochrome c oxidase I protein ∼1.5-fold, citrate synthase activity ∼1.3-fold, 3-hydroxyacyl-CoA dehydrogenase activity ∼1.3-fold, inhibitor of κB-α and inhibitor of κB-β protein content ∼1.3-fold and time to exhaustion in the one-legged knee-extensor endurance exercise test by ∼1.2-fold, with no significant additive or adverse effects of resveratrol on these parameters. Despite an overall ∼25% reduction in total acetylation level in skeletal muscle with resveratrol, no exclusive resveratrol-mediated metabolic effects were observed on the investigated parameters. Notably, however, resveratrol blunted an exercise training-induced decrease (∼20%) in protein carbonylation and decrease (∼40%) in tumour necrosis factor α mRNA content in skeletal muscle. In conclusion, resveratrol did not elicit metabolic improvements in healthy aged subjects; in fact, resveratrol even impaired the observed exercise training-induced improvements in markers of oxidative stress and inflammation in skeletal muscle. Collectively, this highlights the metabolic efficacy of exercise training in aged subjects and does not support the contention that resveratrol is a potential exercise mimetic in healthy aged subjects. PMID:24514907

Does trampoline or hard surface jumping influence lower extremity alignment?

PubMed

Akasaka, Kiyokazu; Tamura, Akihiro; Katsuta, Aoi; Sagawa, Ayako; Otsudo, Takahiro; Okubo, Yu; Sawada, Yutaka; Hall, Toby

2017-12-01

[Purpose] To determine whether repetitive trampoline or hard surface jumping affects lower extremity alignment on jump landing. [Subjects and Methods] Twenty healthy females participated in this study. All subjects performed a drop vertical jump before and after repeated maximum effort trampoline or hard surface jumping. A three-dimensional motion analysis system and two force plates were used to record lower extremity angles, moments, and vertical ground reaction force during drop vertical jumps. [Results] Knee extensor moment after trampoline jumping was greater than that after hard surface jumping. There were no significant differences between trials in vertical ground reaction force and lower extremity joint angles following each form of exercise. Repeated jumping on a trampoline increased peak vertical ground reaction force, hip extensor, knee extensor moments, and hip adduction angle, while decreasing hip flexion angle during drop vertical jumps. In contrast, repeated jumping on a hard surface increased peak vertical ground reaction force, ankle dorsiflexion angle, and hip extensor moment during drop vertical jumps. [Conclusion] Repeated jumping on the trampoline compared to jumping on a hard surface has different effects on lower limb kinetics and kinematics. Knowledge of these effects may be useful in designing exercise programs for different clinical presentations.

Does trampoline or hard surface jumping influence lower extremity alignment?

PubMed Central

Akasaka, Kiyokazu; Tamura, Akihiro; Katsuta, Aoi; Sagawa, Ayako; Otsudo, Takahiro; Okubo, Yu; Sawada, Yutaka; Hall, Toby

2017-01-01

[Purpose] To determine whether repetitive trampoline or hard surface jumping affects lower extremity alignment on jump landing. [Subjects and Methods] Twenty healthy females participated in this study. All subjects performed a drop vertical jump before and after repeated maximum effort trampoline or hard surface jumping. A three-dimensional motion analysis system and two force plates were used to record lower extremity angles, moments, and vertical ground reaction force during drop vertical jumps. [Results] Knee extensor moment after trampoline jumping was greater than that after hard surface jumping. There were no significant differences between trials in vertical ground reaction force and lower extremity joint angles following each form of exercise. Repeated jumping on a trampoline increased peak vertical ground reaction force, hip extensor, knee extensor moments, and hip adduction angle, while decreasing hip flexion angle during drop vertical jumps. In contrast, repeated jumping on a hard surface increased peak vertical ground reaction force, ankle dorsiflexion angle, and hip extensor moment during drop vertical jumps. [Conclusion] Repeated jumping on the trampoline compared to jumping on a hard surface has different effects on lower limb kinetics and kinematics. Knowledge of these effects may be useful in designing exercise programs for different clinical presentations. PMID:29643592

A biomechanical comparison of back and front squats in healthy trained individuals.

PubMed

Gullett, Jonathan C; Tillman, Mark D; Gutierrez, Gregory M; Chow, John W

2009-01-01

The strength and stability of the knee plays an integral role in athletics and activities of daily living. A better understanding of knee joint biomechanics while performing variations of the squat would be useful in rehabilitation and exercise prescription. We quantified and compared tibiofemoral joint kinetics as well as muscle activity while executing front and back squats. Because of the inherent change in the position of the center of mass of the bar between the front and back squat lifts, we hypothesized that the back squat would result in increased loads on the knee joint and that the front squat would result in increased knee extensor and decreased back extensor muscle activity. A crossover study design was used. To assess the net force and torque placed on the knee and muscle activation levels, a combination of video and force data, as well as surface electromyographic data, were collected from 15 healthy trained individuals. The back squat resulted in significantly higher compressive forces and knee extensor moments than the front squat. Shear forces at the knee were small in magnitude, posteriorly directed, and did not vary between the squat variations. Although bar position did not influence muscle activity, muscle activation during the ascending phase was significantly greater than during the descending phase. The front squat was as effective as the back squat in terms of overall muscle recruitment, with significantly less compressive forces and extensor moments. The results suggest that front squats may be advantageous compared with back squats for individuals with knee problems such as meniscus tears, and for long-term joint health.

Periodization effects during short-term resistance training with equated exercise variables in females.

PubMed

Pelzer, Thiemo; Ullrich, Boris; Pfeiffer, Mark

2017-03-01

During resistance training, volume and load can be altered either gradually (traditional periodization: TP) or with frequent changes between subsequent sessions (daily undulating periodization: DUP). We hypothesized that the periodization model employed would not impact upon training-induced adaptations when exercise variables are equated. Nineteen females (22.0 years, moderate resistance training experience of 27.9 months) performed 6 weeks of knee extensor training with 3 weekly sessions exercising one leg using TP and the contralateral leg using DUP. Training load varied between 40, 60, and 80% of one repetition maximum (1RM). Volume, range of motion, and time under tension were equated for each leg with a biofeedback software. Dynamometry, surface EMG and ultrasonography were used to determine temporal changes of knee extensor maximum voluntary strength (MVC), neural drive of the M. quadriceps femoris (QF) and vastus lateralis (VL) and rectus femoris (RF) muscle architecture. Significant (P < 0.05) gains for isometric (TP 15%, DUP 13%) and isokinetic-concentric (TP 8%, DUP 10%) MVC and knee extensor 1RM (TP 18%, DUP 24%) occurred post training. VL and RF-muscle thickness showed significant (P < 0.05) increases ranging from 12 to 20% for TP and from 13 to 19% for DUP. Furthermore, significant (P < 0.05) increases in VL-pennation angle and VL-fascicle length occurred in both legs while QF EMG remained unchanged. No significant temporal differences were found between both models, displaying similar small to large effect sizes. Periodization is no adaptation trigger during short-term resistance training with equated exercise variables.

The effect of age and unilateral leg immobilization for 2 weeks on substrate utilization during moderate-intensity exercise in human skeletal muscle.

PubMed

Vigelsø, A; Gram, M; Dybboe, R; Kuhlman, A B; Prats, C; Greenhaff, P L; Constantin-Teodosiu, D; Birk, J B; Wojtaszewski, J F P; Dela, F; Helge, J W

2016-04-15

This study aimed to provide molecular insight into the differential effects of age and physical inactivity on the regulation of substrate metabolism during moderate-intensity exercise. Using the arteriovenous balance technique, we studied the effect of immobilization of one leg for 2 weeks on leg substrate utilization in young and older men during two-legged dynamic knee-extensor moderate-intensity exercise, as well as changes in key proteins in muscle metabolism before and after exercise. Age and immobilization did not affect relative carbohydrate and fat utilization during exercise, but the older men had higher uptake of exogenous fatty acids, whereas the young men relied more on endogenous fatty acids during exercise. Using a combined whole-leg and molecular approach, we provide evidence that both age and physical inactivity result in intramuscular lipid accumulation, but this occurs only in part through the same mechanisms. Age and inactivity have been associated with intramuscular triglyceride (IMTG) accumulation. Here, we attempt to disentangle these factors by studying the effect of 2 weeks of unilateral leg immobilization on substrate utilization across the legs during moderate-intensity exercise in young (n = 17; 23 ± 1 years old) and older men (n = 15; 68 ± 1 years old), while the contralateral leg served as the control. After immobilization, the participants performed two-legged isolated knee-extensor exercise at 20 ± 1 W (∼50% maximal work capacity) for 45 min with catheters inserted in the brachial artery and both femoral veins. Biopsy samples obtained from vastus lateralis muscles of both legs before and after exercise were used for analysis of substrates, protein content and enzyme activities. During exercise, leg substrate utilization (respiratory quotient) did not differ between groups or legs. Leg fatty acid uptake was greater in older than in young men, and although young men demonstrated net leg glycerol release during exercise, older men showed net glycerol uptake. At baseline, IMTG, muscle pyruvate dehydrogenase complex activity and the protein content of adipose triglyceride lipase, acetyl-CoA carboxylase 2 and AMP-activated protein kinase (AMPK)γ3 were higher in young than in older men. Furthermore, adipose triglyceride lipase, plasma membrane-associated fatty acid binding protein and AMPKγ3 subunit protein contents were lower and IMTG was higher in the immobilized than the contralateral leg in young and older men. Thus, immobilization and age did not affect substrate choice (respiratory quotient) during moderate exercise, but the whole-leg and molecular differences in fatty acid mobilization could explain the age- and immobilization-induced IMTG accumulation. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Physiological Interpretation of the Slope during an Isokinetic Fatigue Test.

PubMed

Bosquet, L; Gouadec, K; Berryman, N; Duclos, C; Gremeaux, V; Croisier, J-L

2015-07-01

To assess the relationship between selected measures (the slope and average performance) obtained during a high intensity isokinetic fatigue test of the knee (FAT) and relevant measures of anaerobic and aerobic capacities. 20 well-trained cyclists performed 3 randomly ordered sessions involving a FAT consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°.s(-1), a maximal continuous graded exercise test (GXT), and a Wingate anaerobic test (WAnT). The slope calculated from peak torque (PT) and total work (TW) of knee extensors was highly associated to maximal PT (r=-0.86) and maximal TW (r=-0.87) measured during FAT, and moderately associated to peak power output measured during the WAnT (r=-0.64 to -0.71). Average PT and average TW were highly associated to maximal PT (r=0.93) and maximal TW (r=0.96), to mean power output measured during WAnT (r=0.83-0.90) and moderately associated to maximal oxygen uptake (0.58-0.67). In conclusion, the slope is mainly determined by maximal anaerobic power, while average performance is a composite measure depending on both aerobic and anaerobic energy systems according to proportions that are determined by the duration of the test. © Georg Thieme Verlag KG Stuttgart · New York.

Fatigue-related firing of muscle nociceptors reduces voluntary activation of ipsilateral but not contralateral lower limb muscles.

PubMed

Kennedy, David S; Fitzpatrick, Siobhan C; Gandevia, Simon C; Taylor, Janet L

2015-02-15

During fatiguing upper limb exercise, maintained firing of group III/IV muscle afferents can limit voluntary drive to muscles within the same limb. It is not known if this effect occurs in the lower limb. We investigated the effects of group III/IV muscle afferent firing from fatigued ipsilateral and contralateral extensor muscles and ipsilateral flexor muscles of the knee on voluntary activation of the knee extensors. In three experiments, we examined voluntary activation of the knee extensors by measuring changes in superimposed twitches evoked by femoral nerve stimulation. Subjects attended on 2 days for each experiment. On one day a sphygmomanometer cuff occluded blood flow of the fatigued muscles to maintain firing of group III/IV muscle afferents. After a 2-min extensor contraction (experiment 1; n = 9), mean voluntary activation was lower with than without maintained ischemia (47 ± 19% vs. 87 ± 8%, respectively; P < 0.001). After a 2-min knee flexor maximal voluntary contraction (MVC) (experiment 2; n = 8), mean voluntary activation was also lower with than without ischemia (59 ± 21% vs. 79 ± 9%; P < 0.01). After the contralateral (left) MVC (experiment 3; n = 8), mean voluntary activation of the right leg was similar with or without ischemia (92 ± 6% vs. 93 ± 4%; P = 0.65). After fatiguing exercise, activity in group III/IV muscle afferents reduces voluntary activation of the fatigued muscle and nonfatigued antagonist muscles in the same leg. However, group III/IV muscle afferents from the fatigued left leg had no effect on the unfatigued right leg. This suggests that any "crossover" of central fatigue in the lower limbs is not mediated by group III/IV muscle afferents. Copyright © 2015 the American Physiological Society.

Contributory factors to unsteadiness during walking up and down stairs in patients with diabetic peripheral neuropathy.

PubMed

Handsaker, Joseph C; Brown, Steven J; Bowling, Frank L; Cooper, Glen; Maganaris, Constantinos N; Boulton, Andrew J M; Reeves, Neil D

2014-11-01

Although patients with diabetic peripheral neuropathy (DPN) are more likely to fall than age-matched controls, the underlying causative factors are not yet fully understood. This study examines the effects of diabetes and neuropathy on strength generation and muscle activation patterns during walking up and down stairs, with implications for fall risk. Sixty-three participants (21 patients with DPN, 21 diabetic controls, and 21 healthy controls) were examined while walking up and down a custom-built staircase. The speed of strength generation at the ankle and knee and muscle activation patterns of the ankle and knee extensor muscles were analyzed. Patients with neuropathy displayed significantly slower ankle and knee strength generation than healthy controls during stair ascent and descent (P < 0.05). During ascent, the ankle and knee extensor muscles were activated significantly later by patients with neuropathy and took longer to reach peak activation (P < 0.05). During descent, neuropathic patients activated the ankle extensors significantly earlier, and the ankle and knee extensors took significantly longer to reach peak activation (P < 0.05). Patients with DPN are slower at generating strength at the ankle and knee than control participants during walking up and down stairs. These changes, which are likely caused by altered activations of the extensor muscles, increase the likelihood of instability and may be important contributory factors for the increased risk of falling. Resistance exercise training may be a potential clinical intervention for improving these aspects and thereby potentially reducing fall risk. © 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

Squatting Exercises in Older Adults: Kinematic and Kinetic Comparisons

PubMed Central

FLANAGAN, SEAN; SALEM, GEORGE J.; WANG, MAN-YING; SANKER, SERENA E.; GREENDALE, GAIL A.

2012-01-01

Purpose Squatting activities may be used, within exercise programs, to preserve physical function in older adults. This study characterized the lower-extremity peak joint angles, peak moments, powers, work, impulse, and muscle recruitment patterns (electromyographic; EMG) associated with two types of squatting activities in elders. Methods Twenty-two healthy, older adults (ages 70–85) performed three trials each of: 1) a squat to a self-selected depth (normal squat; SQ) and 2) a squat onto a chair with a standardized height of 43.8 cm (chair squat; CSQ). Descending and ascending phase joint kinematics and kinetics were obtained using a motion analysis system and inverse dynamics techniques. Results were averaged across the three trials. A 2 × 2 (activity × phase) ANOVA with repeated measures was used to examine the biomechanical differences among the two activities and phases. EMG temporal characteristics were qualitatively examined. Results CSQ generated greater hip flexion angles, peak moments, power, and work, whereas SQ generated greater knee and ankle flexion angles, peak moments, power, and work. SQ generated a greater knee extensor impulse, a greater plantar flexor impulse and a greater total support impulse. The EMG temporal patterns were consistent with the kinetic data. Conclusions The results suggest that, with older adults, CSQ places greater demand on the hip extensors, whereas SQ places greater demand on the knee extensors and ankle plantar flexors. Clinicians may use these discriminate findings to more effectively target specific lower-extremity muscle groups when prescribing exercise for older adults. PMID:12673148

Analysis of Muscle Force-Velocity Parameter Changes in Elderly Women Resulting from Physical Activity--In Continuous Examinations

ERIC Educational Resources Information Center

Skrzek, Anna; Stefanska, Malgorzata

2012-01-01

The aim of the paper was to evaluate changes in muscle force-velocity parameters (F-v) in elderly women subjected to physical exercise. The examinations encompassed 20 women, aged 62-71, who were students at the University of the Third Age in Wroclaw. The evaluation of flexors and extensors of the knee joint, as well as flexors and extensors of…

Effect of whole-body vibration exercise on mobility, balance ability and general health status in frail elderly patients: a pilot randomized controlled trial.

PubMed

Zhang, Li; Weng, Changshui; Liu, Miao; Wang, Qiuhua; Liu, Liming; He, Yao

2014-01-01

To study the effects of whole-body vibration exercises on the mobility function, balance and general health status, and its feasibility as an intervention in frail elderly patients. Pilot randomized controlled trial. Forty-four frail older persons (85.27 ± 3.63 years) meeting the Fried Frailty Criteria. All eligible subjects were randomly assigned to the experimental group, who received a whole-body vibration exercise alone (vibration amplitude: 1-3 mm; frequency: 6-26 Hz; 4-5 bouts × 60 seconds; 3-5 times weekly), or a control group, who received usual care and exercises for eight weeks. The Timed Up and Go Test, 30-second chair stand test, lower extremities muscle strength, balance function, balance confidence and General Health Status were assessed at the beginning of the study, after four weeks and eight weeks of the intervention. Whole-body vibration exercise reduced the time of the Timed Up and Go Test (40.47 ± 15.94 s to 21.34 ± 4.42 s), improved the bilateral knees extensor strength (6.96 ± 1.70 kg to 11.26 ± 2.08 kg), the posture stability (surface area ellipse: 404.58 ± 177.05 to 255.95 ± 107.28) and General Health Status (Short-form Health Survey score: 24.51 ± 10.69 and 49.63 ± 9.85 to 45.03 ± 11.15 and 65.23 ± 9.39, respectively). The repeated-measures ANOVA showed that there were significant differences in the Timed Up and Go Test, 30-second chair stand test, bilateral knees extensor strength, activities-specific balance confidence score and general health status between the two groups (P < 0.05). No side-effects were observed during the training. Whole-body vibration exercise is a safe and effective method that can improve the mobility, knee extensor strength, balance and the general health status in the frail elderly.

Effectiveness of Aquatic Exercise in Improving Lower Limb Strength in Musculoskeletal Conditions: A Systematic Review and Meta-Analysis.

PubMed

Heywood, Sophie; McClelland, Jodie; Mentiplay, Benjamin; Geigle, Paula; Rahmann, Ann; Clark, Ross

2017-01-01

To investigate the effectiveness of aquatic exercise in improving lower limb strength in people with musculoskeletal conditions. A systematic search used 5 databases, including MEDLINE, CINAHL, Embase, SPORTDiscus, and The Cochrane Library. Randomized controlled trials evaluating aquatic exercise with a resistance training component for adults with musculoskeletal conditions compared with no intervention or land-based exercise were identified. Fifteen studies from the initial yield of 1214 met these criteria. Data related to participant demographics, study design, and methods, interventions, and outcomes, including numerical means and SDs, were extracted independently by 2 reviewers. Nine of the 15 studies were of high quality, scoring at least 6 on the Physiotherapy Evidence Database Scale. Limited consideration of the prescription of resistance in the aquatic exercise and application of resistance training principles existed. Low- or very low-quality evidence indicates there was no difference in average effect between aquatic exercise and no exercise in improving hip abductor strength (standardized mean difference [SMD], .28; 95% confidence interval [CI], -.04 to .59), knee extensor strength (SMD, .18; 95% CI, -.03 to .40), knee flexor strength (SMD, .13; 95% CI, -.20 to .45), or lower limb endurance (SMD, .35; 95% CI, -.06 to .77). Low-quality evidence indicates no difference in average effect between aquatic and land exercise for knee extensor (SMD, -.24; 95% CI, -.49 to .02) or flexor strength (SMD, -.15; 95% CI, -.53 to .22). It is likely that the inadequate application of resistance in water is a significant contributor to the limited effectiveness of aquatic exercise interventions in improving hip and knee muscle strength in people with musculoskeletal conditions. Future research is needed to quantify resistance with aquatic exercises and to determine if using opportunities for greater resistance in aquatic rehabilitation and appropriate resistance training principles can be more effective in improving muscle strength. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Changes in Gait over a 30-min Walking Session in Obese Females.

PubMed

Singh, Bhupinder; Vo, Huy; Francis, Shelby L; Janz, Kathleen F; Yack, H John

2017-03-01

This study assessed the biomechanical gait changes in obese and normal-weight female adult subjects after a commonly recommended 30-min walking session. Hip and knee adduction and extensor moments, which are the primary modulators of frontal and sagittal plane load distribution, were hypothesized to increase in obese females after a 30-min walking period, resulting in more stress across the hip and knee joint. Ten obese (37.7 ± 4.8 yr of age, body mass index [BMI] = 36.1 ± 4.2 kg·m) and 10 normal-weight control female subjects (38.1 ± 4.5 yr of age, BMI = 22.6 ± 2.3 kg·m) walked 30 min continuously on the treadmill at their self-selected speed. V˙O2max was estimated using Ebbeling protocol. A three-dimensional pre- and posttreadmill gait analysis was conducted using infrared markers and force plates to calculate hip and knee moments. Knee extensor moments increased in both obese, pretreadmill (0.54 ± 0.28 N·m·kg) to posttreadmill (0.78 ± 0.43 N·m·kg) (P = 0.01), and control subjects, pretreadmill (0.57 ± 0.34 N·m·kg) to posttreadmill (0.80 ± 0.49 N·m·kg) (P = 0.02). Hip extensor moments decreased for both obese and control subjects. Knee adduction moments did not change in either obese or control subjects. Knee extensor and adductor moments showed good to moderate relationships with V˙O2max, but not BMI or waist circumference. Obese and normal-weight subjects experienced an increase in knee extensor moments after 30 min of walking similarly; therefore, clinicians do not need special consideration for obese individuals when recommending 30-min walking sessions. Fitness may be the important factor in judging the implications of exercise on joint mechanics and parameters of a walking program.

Knee extension range of motion and self-report physical function in total knee arthroplasty: mediating effects of knee extensor strength

PubMed Central

2013-01-01

Background Knee extensor strength and knee extension range of motion (ROM) are important predictors of physical function in patients with a total knee arthroplasty (TKA). However, the relationship between the two knee measures remains unclear. The purpose of this study was to examine whether changes in knee extensor strength mediate the association between changes in knee extension ROM and self-report physical function. Methods Data from 441 patients with a TKA were collected preoperatively and 6 months postoperatively. Self-report measure of physical function was assessed by the Short Form 36 (SF-36) questionnaire. Knee extensor strength was measured by handheld dynamometry and knee extension ROM by goniometry. A bootstrapped cross product of coefficients approach was used to evaluate mediation effects. Results Mediation analyses, adjusted for clinicodemographic measures, revealed that the association between changes in knee extension ROM and SF-36 physical function was mediated by changes in knee extensor strength. Conclusions In patients with TKA, knee extensor strength mediated the influence of knee extension ROM on physical function. These results suggest that interventions to improve the range of knee extension may be useful in improving knee extensor performance. PMID:23332039

The Effects of High-Intensity versus Low-Intensity Resistance Training on Leg Extensor Power and Recovery of Knee Function after ACL-Reconstruction

PubMed Central

Aue Sobol, Nanna; Andersen, Lars L.; Kiel, Peter; Løfholm, Peter; Magnusson, S. Peter; Krogsgaard, Michael R.

2014-01-01

Objective. Persistent weakness is a common problem after anterior cruciate ligament- (ACL-) reconstruction. This study investigated the effects of high-intensity (HRT) versus low-intensity (LRT) resistance training on leg extensor power and recovery of knee function after ACL-reconstruction. Methods. 31 males and 19 females were randomized to HRT (n = 24) or LRT (n = 26) from week 8–20 after ACL-reconstruction. Leg extensor power, joint laxity, and self-reported knee function were measured before and 7, 14, and 20 weeks after surgery. Hop tests were assessed before and after 20 weeks. Results. Power in the injured leg was 90% (95% CI 86–94%) of the noninjured leg, decreasing to 64% (95% CI 60–69%) 7 weeks after surgery. During the resistance training phase there was a significant group by time interaction for power (P = 0.020). Power was regained more with HRT compared to LRT at week 14 (84% versus 73% of noninjured leg, resp.; P = 0.027) and at week 20 (98% versus 83% of noninjured leg, resp.; P = 0.006) without adverse effects on joint laxity. No other between-group differences were found. Conclusion. High-intensity resistance training during rehabilitation after ACL-reconstruction can improve muscle power without adverse effects on joint laxity. PMID:24877078

Muscle Fatigue during Intermittent Exercise in Individuals with Mental Retardation

ERIC Educational Resources Information Center

Zafeiridis, Andreas; Giagazoglou, Paraskevi; Dipla, Konstantina; Salonikidis, Konstantinos; Karra, Chrisanthi; Kellis, Eleftherios

2010-01-01

This study examined fatigue profile during intermittent exercise in 10 men with mild to moderate mental retardation (MR) and 10 men without mental retardation (C). They performed 4 x 30 s maximal knee extensions and flexions with 1-min rest on an isokinetic dynamometer. Peak torque of flexors (PTFL) and extensors (PTEX), total work (TW), and…

Quadriceps strengthening with and without blood flow restriction in the treatment of patellofemoral pain: a double-blind randomised trial.

PubMed

Giles, Lachlan; Webster, Kate E; McClelland, Jodie; Cook, Jill L

2017-12-01

Quadriceps strengthening exercises are part of the treatment of patellofemoral pain (PFP), but the heavy resistance exercises may aggravate knee pain. Blood flow restriction (BFR) training may provide a low-load quadriceps strengthening method to treat PFP. Seventy-nine participants were randomly allocated to a standardised quadriceps strengthening (standard) or low-load BFR. Both groups performed 8 weeks of leg press and leg extension, the standard group at 70% of 1 repetition maximum (1RM) and the BFR group at 30% of 1RM. Interventions were compared using repeated-measures analysis of variance for Kujala Patellofemoral Score, Visual Analogue Scale for 'worst pain' and 'pain with daily activity', isometric knee extensor torque (Newton metre) and quadriceps muscle thickness (cm). Subgroup analyses were performed on those participants with painful resisted knee extension at 60°. Sixty-nine participants (87%) completed the study (standard, n=34; BFR, n=35). The BFR group had a 93% greater reduction in pain with activities of daily living (p=0.02) than the standard group. Participants with painful resisted knee extension (n=39) had greater increases in knee extensor torque with BFR than standard (p<0.01). No between-group differences were found for change in Kujala Patellofemoral Score (p=0.31), worst pain (p=0.24), knee extensor torque (p=0.07) or quadriceps thickness (p=0.2). No difference was found between interventions at 6 months. Compared with standard quadriceps strengthening, low load with BFR produced greater reduction in pain with daily living at 8 weeks in people with PFP. Improvements were similar between groups in worst pain and Kujala score. The subgroup with painful resisted knee extension had larger improvements in quadriceps strength from BFR. 12614001164684. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Effect of Superimposed Electromyostimulation on Back Extensor Strengthening: A Pilot Study.

PubMed

Park, Jae Hyeon; Seo, Kwan Sik; Lee, Shi-Uk

2016-09-01

Park, JH, Seo, KS, and Lee, S-U. Effect of superimposed electromyostimulation on back extensor strengthening: a pilot study. J Strength Cond Res 30(9): 2470-2475, 2016-Electromyostimulation (EMS) superimposed on voluntary contraction (VC) can increase muscle strength. However, no study has examined the effect of superimposing EMS on back extensor strengthening. The purpose of this study was to determine the effect of superimposed EMS on back extensor strengthening in healthy adults. Twenty healthy men, 20-29 years of age, without low-back pain were recruited. In the EMS group, electrodes were attached to bilateral L2 and L4 paraspinal muscles. Stimulation intensity was set for maximally tolerable intensity. With VC, EMS was superimposed for 10 seconds followed by a 20-second rest period. The same protocol was used in the sham stimulation (SS) group, except that the stimulation intensity was set at the lowest intensity (5 mA). All subjects performed back extension exercise using a Swiss ball, with 10 repetitions per set, 2 sets each day, 5 times a week for 2 weeks. The primary outcome measure was the change in isokinetic strength of the back extensor using an isokinetic dynamometer. Additionally, endurance was measured using the Sorensen test. After 2 weeks of back extension exercise, the peak torque and endurance increased significantly in both groups (p ≤ 0.05). Effect size between the EMS group and the SS group was medium in strength and endurance. However, there was no statistically significant difference between 2 groups. In conclusion, 2 weeks of back extensor strengthening exercise was effective for strength and endurance. Superimposing EMS on back extensor strengthening exercise could provide an additional effect on increasing strength.

Effect of Knee Joint Angle and Contraction Intensity on Hamstrings Coactivation.

PubMed

Wu, Rui; Delahunt, Eamonn; Ditroilo, Massimiliano; Lowery, Madeleine M; DE Vito, Giuseppe

2017-08-01

This study investigated the effect of knee joint angle and contraction intensity on the coactivation of the hamstring muscles (when acting as antagonists to the quadriceps) in young and older individuals of both sexes. A total of 25 young (24 ± 2.6 yr) and 26 older (70 ± 2.5 yr) healthy men and women participated. Maximal voluntary isometric contraction of the knee extensors and flexors was assessed at two knee joint angles (90° and 60°, 0° = full extension). At each angle, participants performed submaximal contractions of the knee extensors (20%, 50%, and 80% maximal voluntary isometric contraction), whereas surface EMG was simultaneously acquired from the vastus lateralis and biceps femoris muscles to assess the level (EMG root-mean-square) of agonist activation and antagonist coactivation. Subcutaneous adipose tissue in the areas corresponding to surface EMG electrode placements was measured via ultrasonography. The contractions performed at 90° knee flexion demonstrated higher levels of antagonist coactivation (all P < 0.01) and agonist activation (all P < 0.01) as a function of contraction intensity compared with the 60° knee flexion. Furthermore, after controlling for subcutaneous adipose tissue, older participants exhibited a higher level of antagonist coactivation at 60° knee flexion compared with young participants (P < 0.05). The results of the present study suggest that 1) the antagonist coactivation is dependent on knee joint angle and contraction intensity and 2) subcutaneous adipose tissue may affect the measured coactivation level likely because of a cross-talk effect. Antagonist coactivation may play a protective role in stabilizing the knee joint and maintaining constant motor output.

An approach to counteracting long-term microgravity-induced muscle atrophy

NASA Technical Reports Server (NTRS)

Tesch, P. A.; Buchanan, P.; Dudley, G. A.

1990-01-01

To find means of alleviating muscle atrophy induced by long-term microgravity, the effects of a 19-week-long heavy-resistance training regime (using either concentric muscle actions only or concentric and eccentric muscle actions) on the strengths of the exercised knee extensor muscle group were investigated in two groups of male human subjects performing two types of training exercises: supine leg press or/and seated knee extension. Results show that a training program in which both the concentric and the eccentric muscle action was performed led to substantially greater increases in maximal muscle strength than when only concentric exercises were performed.

Knee strength, power and stair performance of the elderly 5 years after unicompartmental knee arthroplasty.

PubMed

Li, Yumeng; Kakar, Rumit S; Fu, Yang-Chieh; Mahoney, Ormonde M; Kinsey, Tracy L; Simpson, Kathy J

2018-04-13

Unicompartmental knee arthroplasty (UKA) has been shown to demonstrate some satisfactory short-term outcomes. However, to our knowledge, there have been no reports on midterm or long-term knee extensor strength and leg extensor power post-UKA. Therefore, the purposes of this study were: (1) to assess the isokinetic knee extensor strength, leg extensor power and stair performance of elderly participants at 5 years UKA post-operation; (2) to compare the differences in knee extensor strength and leg extensor power between the UKA and contralateral healthy limbs. Nineteen elderly participants (75 ± 5 years) who had a medial or a lateral compartment UKA at 5 years post-operation were recruited. The isokinetic knee extensor strength and leg extensor power were measured. The stair performance was tested on a 4-step stair, and ascent and descent velocities were calculated. The pain level was assessed. The UKA limbs' knee extensor strength and leg extensor power were 1.01 ± 0.39 Nm/kg and 0.98 ± 0.27 W/kg, respectively. The stair ascent and descent velocities were 0.37 ± 0.07 and 0.38 ± 0.11 m/s, respectively. In addition, the UKA limbs exhibited comparable knee strength and leg power relative to the contralateral limbs. In general, the knee extensor strength and leg extensor power exhibited by the UKA limbs at 5 years post-operation may be typical in comparison with the normative data. We suggest that UKA is a satisfactory treatment in regard to the recovery of knee strength, leg power and ability to climb up and down stairs.

The Effects of a Motorized Aquatic Treadmill Exercise Program on Muscle Strength, Cardiorespiratory Fitness, and clinical function in Subacute Stroke Patients -- a Randomized Controlled Pilot Trial.

PubMed

Lee, So Young; Han, Eun Young; Kim, Bo Ryun; Im, Sang Hee

2018-03-12

The aim of this study was to assess the effects of a motorized aquatic treadmill exercise program improve the isometric strength of the knee muscles, cardiorespiratory fitness, arterial stiffness, motor function, balance, functional outcomes and quality of life in subacute stroke patients. Thirty-two patients were randomly assigned to 4-week training sessions of either aquatic therapy(n=19) or land-based aerobic exercise(n=18). Isometric strength was measured using an isokinetic dynamometer. Cardiopulmonary fitness was evaluated using a symptom-limited exercise tolerance test and by measuring brachial ankle pulse wave velocity. Moreover, motor function(Fugl-Meyer Assessment[FMA] and FMA-lower limb[FMA-LL]), balance(Berg Balance Scale[BBS]), Activities of daily living(Korean version of the Modified Barthel Index [K-MBI]), and Quality of life(EQ-5D index) were examined. There were no inter-group differences between demographic and clinical characteristics at baseline(p>0.05). The results shows significant improvements in peak oxygen consumption (p=0.02), maximal isometric strength of the bilateral knee extensors (p<0.01) and paretic knee flexors (p=0.01), FMA (p=0.03), FMA-LL (p=0.01), BBS (p=0.01), K-MBI (p<0.01), and EQ-5D index (p=0.04) after treatment in the aquatic therapy group. However, only significant improvements in maximal isometric strength in the knee extensors (p=0.03) and flexors (p=0.04) were found within the aquatic therapy group and control group. Water-based aerobic exercise performed on a motorized aquatic treadmill had beneficial effect on isometric muscle strength in the lower limb.

Hip-Extensor Strength, Trunk Posture, and Use of the Knee-Extensor Muscles During Running.

PubMed

Teng, Hsiang-Ling; Powers, Christopher M

2016-07-01

Diminished hip-muscle performance has been proposed to contribute to various knee injuries. To determine the association between hip-extensor muscle strength and sagittal-plane trunk posture and the relationships among hip-extensor muscle strength and hip- and knee-extensor work during running. Descriptive laboratory study. Musculoskeletal biomechanical laboratory. A total of 40 asymptomatic recreational runners, 20 men (age = 27.1 ± 7.0 years, height = 1.74 ± 0.69 m, mass = 71.1 ± 8.2 kg) and 20 women (age = 26.2 ± 5.8 years, height = 1.65 ± 0.74 m, mass = 60.6 ± 6.6 kg), participated. Maximum isometric strength of the hip extensors was assessed using a dynamometer. Sagittal-plane trunk posture (calculated relative to the global vertical axis) and hip- and knee-extensor work (sum of energy absorption and generation) during the stance phase of running were quantified while participants ran over ground at a controlled speed of 3.4 m/s. We used Pearson product moment correlations to examine the relationships among hip-extensor strength, mean sagittal-plane trunk-flexion angle, hip-extensor work, and knee-extensor work. Hip-extensor strength was correlated positively with trunk-flexion angle (r = 0.55, P < .001) and hip-extensor work (r = 0.46, P = .003). It was correlated inversely with knee-extensor work (r = -0.39, P = .01). All the correlations remained after adjusting for sex. Our findings suggest that runners with hip-extensor weakness used a more upright trunk posture. This strategy led to an overreliance on the knee extensors and may contribute to overuse running injuries at the knee.

Hip-Extensor Strength, Trunk Posture, and Use of the Knee-Extensor Muscles During Running

PubMed Central

Teng, Hsiang-Ling; Powers, Christopher M.

2016-01-01

Context:  Diminished hip-muscle performance has been proposed to contribute to various knee injuries. Objective:  To determine the association between hip-extensor muscle strength and sagittal-plane trunk posture and the relationships among hip-extensor muscle strength and hip- and knee-extensor work during running. Design:  Descriptive laboratory study. Setting:  Musculoskeletal biomechanical laboratory. Patients or Other Participants:  A total of 40 asymptomatic recreational runners, 20 men (age = 27.1 ± 7.0 years, height = 1.74 ± 0.69 m, mass = 71.1 ± 8.2 kg) and 20 women (age = 26.2 ± 5.8 years, height = 1.65 ± 0.74 m, mass = 60.6 ± 6.6 kg), participated. Main Outcome Measure(s):  Maximum isometric strength of the hip extensors was assessed using a dynamometer. Sagittal-plane trunk posture (calculated relative to the global vertical axis) and hip- and knee-extensor work (sum of energy absorption and generation) during the stance phase of running were quantified while participants ran over ground at a controlled speed of 3.4 m/s. We used Pearson product moment correlations to examine the relationships among hip-extensor strength, mean sagittal-plane trunk-flexion angle, hip-extensor work, and knee-extensor work. Results:  Hip-extensor strength was correlated positively with trunk-flexion angle (r = 0.55, P < .001) and hip-extensor work (r = 0.46, P = .003). It was correlated inversely with knee-extensor work (r = −0.39, P = .01). All the correlations remained after adjusting for sex. Conclusions:  Our findings suggest that runners with hip-extensor weakness used a more upright trunk posture. This strategy led to an overreliance on the knee extensors and may contribute to overuse running injuries at the knee. PMID:27513169

A randomized controlled trial on the effects of combined aerobic-resistance exercise on muscle strength and fatigue, glycemic control and health-related quality of life of type 2 diabetes patients.

PubMed

Tomas-Carus, Pablo; Ortega-Alonso, Alfredo; Pietilainen, Kirsi H; Santos, Vitoria; Goncalves, Helena; Ramos, Jorge; Raimundo, Armando

2016-05-01

The aim of this paper was to evaluate the effects of a 12-weeks combined aerobic-resistance exercise therapy on fatigue and isokinetic muscle strength, glycemic control and health-related quality of life (HRQoL) in moderately affected type 2 diabetes (T2DM) patients. A randomized controlled trial design was employed. Forty-three T2DM patients were assigned to an exercise group (N.=22), performing 3 weekly sessions of 60 minutes of combined aerobic-resistance exercise for 12-weeks; or a no exercise control group (N.=21). Both groups were evaluated at a baseline and after 12-weeks of exercise therapy for: 1) muscle strength and fatigue by isokinetic dynamometry; 2) plasma glycated hemoglobin A1C (HbA1C); and 3) HRQoL utilizing the SF-36 questionnaire. The exercise therapy led to improvements in muscle fatigue in knee extensors (-55%) and increased muscle strength in knee flexors and extensors (+15 to +30%), while HbA1C decreased (-18%). In addition, the exercising patients showed sizeable improvements in HRQoL: physical function (+53%), vitality (+21%) and mental health (+40%). Twelve-weeks of combined aerobic-resistance exercise was highly effective to improve muscle strength and fatigue, glycemic control and several aspects of HRQoL in T2DM patients. These data encourage the use of aerobic and resistance exercise in the good clinical care of T2DM.

Postexercise blood flow restriction does not enhance muscle hypertrophy induced by multiple-set high-load resistance exercise.

PubMed

Madarame, Haruhiko; Nakada, Satoshi; Ohta, Takahisa; Ishii, Naokata

2018-05-01

To test the applicability of postexercise blood flow restriction (PEBFR) in practical training programmes, we investigated whether PEBFR enhances muscle hypertrophy induced by multiple-set high-load resistance exercise (RE). Seven men completed an eight-week RE programme for knee extensor muscles. Employing a within-subject design, one leg was subjected to RE + PEBFR, whereas contralateral leg to RE only. On each exercise session, participants performed three sets of unilateral knee extension exercise at approximately 70% of their one-repetition maximum for RE leg first, and then performed three sets for RE + PEBFR leg. Immediately after completion of the third set, the proximal portion of the RE + PEBFR leg was compressed with an air-pressure cuff for 5 min at a pressure ranging from 100 to 150 mmHg. If participants could perform 10 repetitions for three sets in two consecutive exercise sessions, the work load was increased by 5% at the next exercise session. Muscle thickness and strength of knee extensor muscles were measured before and after the eight-week training period and after the subsequent eight-week detraining period. There was a main effect of time but no condition × time interaction or main effect of condition for muscle thickness and strength. Both muscle thickness and strength increased after the training period independent of the condition. This result suggests that PEBFR would not be an effective training method at least in an early phase of adaptation to high-load resistance exercise. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Sex Comparison of Knee Extensor Size, Strength and Fatigue Adaptation to Sprint Interval Training.

PubMed

Bagley, Liam; Al-Shanti, Nasser; Bradburn, Steven; Baig, Osamah; Slevin, Mark; McPhee, Jamie S

2018-03-12

Regular sprint interval training (SIT) improves whole-body aerobic capacity and muscle oxidative potential, but very little is known about knee extensor anabolic or fatigue resistance adaptations, or whether effects are similar for males and females. The purpose of this study was to compare sex-related differences in knee extensor size, torque-velocity relationship and fatigability adaptations to 12 weeks SIT. Sixteen males and fifteen females (mean (SEM) age: 41 (±2.5) yrs) completed measurements of total body composition assessed by DXA, quadriceps muscle cross-sectional area (CSAQ) assessed by MRI, the knee extensor torque-velocity relationship (covering 0 - 240°·sec) and fatigue resistance, which was measured as the decline in torque from the first to the last of 60 repeated concentric knee extensions performed at 180°·sec. SIT consisted of 4 x 20 second sprints on a cycle ergometer set at an initial power output of 175% of power at VO2max, three times per week for 12 weeks. CSAQ increased by 5% (p=0.023) and fatigue resistance improved 4.8% (p=0.048), with no sex differences in these adaptations (sex comparisons: p=0.140 and p=0.282, respectively). Knee extensor isometric and concentric torque was unaffected by SIT in both males and females (p>0.05 for all velocities). 12 weeks SIT, totalling 4 minutes very intense cycling per week, significantly increased fatigue resistance and CSAQ similarly in males and females, but did not significantly increase torque in males or females. These results suggest that SIT is a time-effective training modality for males and females to increase leg muscle size and fatigue resistance.

Changes in muscle cross-sectional area, muscle force, and jump performance during 6 weeks of progressive whole-body vibration combined with progressive, high intensity resistance training

PubMed Central

Rosenberger, A.; Beijer, Å.; Johannes, B.; Schoenau, E.; Mester, J.; Rittweger, J.; Zange, J.

2017-01-01

Objectives: We hypothesized that progressive whole-body vibration (WBV) superimposed to progressive high intensity resistance training has greater effects on muscle cross-sectional area (CSA), muscle force of leg muscles, and jump performance than progressive high intensity resistance training alone. Methods: Two groups of healthy male subjects performed either 6 weeks of Resistive Vibration Exercise (RVE, squats and heel raises with WBV, n=13) or Resistive Exercise (RE, squats and heel raises without WBV, n=13). Squats under RVE required indispensable weight loading on the forefoot to damp harmful vibrations to the head. Time, intervention, and interaction effects were analyzed. Results: After 6 weeks of training, knee extensor CSA, isometric knee extension force, and counter movement jump height increased equally in both groups (time effect, P<0.001, P≤0.02, and P≤0.03, respectively), whereas only in RVE ankle plantar flexor CSA and isometric ankle plantar flexion force reached significance or a tendency, respectively, (time effect, P=0.015 and P=0.069, respectively; intervention effect also for the latter, P=0.006). Drop jump contact time did significantly more improve in RVE (interaction effect, P=0.042). Conclusions: RVE showed better training effects than RE only in plantar flexor muscles. RVE seems to be suitable in professional sports with a special focus on calf muscles. PMID:28574410

Muscular activity during dynamic squats in patients with ACL reconstruction.

PubMed

Ceaglio, Sebastian; Alberto, Federico; Catalfamo, Paola Andrea; Braidot, Ariel Andres

2010-01-01

One of the most frequent injuries in subjects who practice sport is the rupture of the anterior cruciate ligament (ACL). Appropriate reconstruction and rehabilitation are key issues in full recovery of patients and their return to previous activities. This paper presents a new method to estimate muscle strength during a dynamic exercise from kinematic and electromyographic (EMG) data. Recovery of patients with ACL rupture and reconstruction was evaluated 4 and 6 months after surgery by assessing the differences in knee extensor and flexor muscle activity between the unimpaired and injured limbs. The results show that squat EMGs from the extensor muscles of the knee from the injured and unimpaired limb could help assess rehabilitation outputs in patients who had undergone an ACL reconstructive surgery.

Pilates improves lower limbs strength and postural control during quite standing in a child with hemiparetic cerebral palsy: A case report study.

PubMed

Dos Santos, Adriana Neves; Serikawa, Simoni Sayuri; Rocha, Nelci Adriana Cicuto Ferreira

2016-08-01

To verify the effect of Pilates exercises in a child with cerebral palsy (CP) with mild functional impairment. We evaluated average peak torque of ankle and knee extensors/flexors using a Biodex System, using concentric active-assisted test. We also evaluated amplitude of anterior-posterior and of medial-lateral displacement of the CoP and area of oscillation during quite standing with a BERTEC platform. We applied Pilates exercises for eight weeks. Peak torque/body weight of ankle and knee extensors/flexors of both affected and unaffected limbs increased after Pilates. Also, all kinetic variables decreased after Pilates' intervention. After one-month follow-up, isokinetic variable values were higher while kinetic variable values were lower than baseline values. Pilates may be an important rehabilitation technique for children with CP that present mild deficits in motor structures and high functional level, especially when the aims are to improve muscle strength and postural control during quite standing.

Isokinetic and isometric strength in osteoarthrosis of the knee. A comparative study with healthy women.

PubMed

Tan, J; Balci, N; Sepici, V; Gener, F A

1995-01-01

Dynamic stability of the knee joint depends on the appropriate strength ratio of quadriceps and hamstring muscles. The purpose of this investigation was to determine the maximum peak torque (MPT) and MPT ratios of hamstrings to quadriceps (H/Q) muscles in patients with knee osteoarthritis (OA). Two groups of patients were included in the study. The first group consisted of 30 patients (Group A) with the clinical and radiologic findings of knee OA. The second group consisted of 30 patients (Group B) exhibiting knee joint pain without roentgenologic findings of knee OA. The findings of two patient groups were compared with each other and also with 30 healthy subjects (Group C). Isokinetic (at 60 degrees/s and at 180 degrees/s) and isometric (at 30 degrees and at 60 degrees of knee flexion) tests were performed by the rate-limiting isokinetic dynamometer system. Isokinetic and isometric MPT loss of knee flexors and extensors was found in both patient groups with respect to controls, but MPT ratios of H/Q muscles did not show a statistically significant difference compared with the control group. This may be related to the equal strength loss of knee flexors and knee extensors in patients with knee OA. It is concluded that strengthening exercises of hamstring muscles is as important as quadriceps strengthening in rehabilitation of knee OA.

Gait biomechanics of skipping are substantially different than those of running.

PubMed

McDonnell, Jessica; Willson, John D; Zwetsloot, Kevin A; Houmard, Joseph; DeVita, Paul

2017-11-07

The inherit injury risk associated with high-impact exercises calls for alternative ways to achieve the benefits of aerobic exercise while minimizing excessive stresses to body tissues. Skipping presents such an alternative, incorporating double support, flight, and single support phases. We used ground reaction forces (GRFs), lower extremity joint torques and powers to compare skipping and running in 20 healthy adults. The two consecutive skipping steps on each limb differed significantly from each other, and from running. Running had the longest step length, the highest peak vertical GRF, peak knee extensor torque, and peak knee negative and positive power and negative and positive work. Skipping had the greater cadence, peak horizontal GRF, peak hip and ankle extensor torques, peak ankle negative power and work, and peak ankle positive power. The second vs first skipping step had the shorter step length, higher cadence, peak horizontal GRF, peak ankle extensor torque, and peak ankle negative power, negative work, and positive power and positive work. The first skipping step utilized predominately net negative joint work (eccentric muscle action) while the second utilized predominately net positive joint work (concentric muscle action). The skipping data further highlight the persistence of net negative work performed at the knee and net positive work performed at the ankle across locomotion gaits. Evidence of step segregation was seen in distribution of the braking and propelling impulses and net work produced across the hip, knee, and ankle joints. Skipping was substantially different than running and was temporally and spatially asymmetrical with successive foot falls partitioned into a dominant function, either braking or propelling whereas running had a single, repeated step in which both braking and propelling actions were performed equally. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of six weeks endurance training on dynamic muscular control of the knee following fatiguing exercise.

PubMed

Hassanlouei, H; Falla, D; Arendt-Nielsen, L; Kersting, U G

2014-10-01

The aim of the study was to examine whether six weeks of endurance training minimizes the effects of fatigue on postural control during dynamic postural perturbations. Eighteen healthy volunteers were assigned to either a 6-week progressive endurance training program on a cycle ergometer or a control group. At week 0 and 7, dynamic exercise was performed on an ergometer until exhaustion and immediately after, the anterior-posterior centre of pressure (COP) sway was analyzed during full body perturbations. Maximal voluntary contractions (MVC) of the knee flexors and extensors, muscle fiber conduction velocity (MFCV) of the vastus lateralis and medialis during sustained isometric knee extension contractions, and power output were measured. Following the training protocol, maximum knee extensor and flexor force and power output increased significantly for the training group with no changes observed for the control group. Moreover, the reduction of MFCV due to fatigue changed for the training group only (from 8.6% to 3.4%). At baseline, the fatiguing exercise induced an increase in the centre of pressure sway during the perturbations in both groups (>10%). The fatiguing protocol also impaired postural control in the control group when measured at week 7. However, for the training group, sway was not altered after the fatiguing exercise when assessed at week 7. In summary, six weeks of endurance training delayed the onset of muscle fatigue and improved the ability to control balance in response to postural perturbations in the presence of muscle fatigue. Results implicate that endurance training should be included in any injury prevention program. Copyright © 2014 Elsevier Ltd. All rights reserved.

Knee extensor strength and body weight in adolescent men and the risk of knee osteoarthritis by middle age.

PubMed

Turkiewicz, Aleksandra; Timpka, Simon; Thorlund, Jonas Bloch; Ageberg, Eva; Englund, Martin

2017-10-01

To assess the extent to which knee extensor strength and weight in adolescence are associated with knee osteoarthritis (OA) by middle age. We studied a cohort of 40 121 men who at age 18 years in 1969/1970 underwent mandatory conscription in Sweden. We retrieved data on isometric knee extensor strength, weight, height, smoking, alcohol consumption, parental education and adult occupation from Swedish registries. We identified participants diagnosed with knee OA or knee injury from 1987 to 2010 through the National Patient Register. We estimated the HR of knee OA using multivariable-adjusted Cox proportional regression model. To assess the influence of adult knee injury and occupation, we performed a formal mediation analysis. The mean (SD) knee extensor strength was 234 (47) Nm, the mean (SD) weight was 66 (9.3) kg. During 24 years (median) of follow-up starting at the age of 35 years, 2049 persons were diagnosed with knee OA. The adjusted HR (95% CI) of incident knee OA was 1.12 (1.06 to 1.18) for each SD of knee extensor strength and 1.18 (1.15 to 1.21) per 5 kg of body weight. Fifteen per cent of the increase in OA risk due to higher knee extensor strength could be attributed to knee injury and adult occupation. Higher knee extensor strength in adolescent men was associated with increased risk of knee OA by middle age, challenging the current tenet of low muscle strength being a risk factor for OA. We confirmed higher weight to be a strong risk factor for knee OA. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Changes in fatigue, multiplanar knee laxity, and landing biomechanics during intermittent exercise.

PubMed

Shultz, Sandra J; Schmitz, Randy J; Cone, John R; Henson, Robert A; Montgomery, Melissa M; Pye, Michele L; Tritsch, Amanda J

2015-05-01

Knee laxity increases during exercise. However, no one, to our knowledge, has examined whether these increases contribute to higher-risk landing biomechanics during prolonged, fatiguing exercise. To examine associations between changes in fatigue (measured as sprint time [SPTIME]), multiplanar knee laxity (anterior-posterior [APLAX], varus-valgus [VVLAX] knee laxity, and internal-external rotation [IERLAX]) knee laxity and landing biomechanics during prolonged, intermittent exercise. Descriptive laboratory study. Laboratory and gymnasium. A total of 30 male (age = 20.3 ± 2.0 years, height = 1.79 ± 0.05 m, mass = 75.2 ± 7.2 kg) and 29 female (age = 20.5 ± 2.3 years, height = 1.67 ± 0.08 m, mass = 61.8 ± 9.0 kg) competitive athletes. A 90-minute intermittent exercise protocol (IEP) designed to simulate the physiologic and biomechanical demands of a soccer match. We measured SPTIME, APLAX, and landing biomechanics before and after warm-up, every 15 minutes during the IEP, and every 15 minutes for 1 hour after the IEP. We measured VVLAX and IERLAX before and after the warm-up, at 45 and 90 minutes during the IEP, and at 30 minutes after the IEP. We used hierarchical linear modeling to examine associations between exercise-related changes in SPTIME and knee laxity with exercise-related changes in landing biomechanics while controlling for initial (before warm-up) knee laxity. We found that SPTIME had a more global effect on landing biomechanics in women than in men, resulting in a more upright landing and a reduction in landing forces and out-of-plane motions about the knee. As APLAX increased with exercise, women increased their knee internal-rotation motion (P = .02), and men increased their hip-flexion motion and energy-absorption (P = .006) and knee-extensor loads (P = .04). As VVLAX and IERLAX increased, women went through greater knee-valgus motion and dorsiflexion and absorbed more energy at the knee (P ≤ .05), whereas men were positioned in greater hip external and knee internal rotation and knee valgus throughout the landing (P = .03). The observed fatigue- and laxity-related changes in landing biomechanics during exercise often depended on initial knee laxity. Both exercise-related changes in fatigue and knee laxity were associated with higher-risk landing biomechanics during prolonged exercise. These relationships were more pronounced in participants with greater initial knee laxity.

Associations of knee extensor strength and standing balance with physical function in knee osteoarthritis.

PubMed

Pua, Yong-Hao; Liang, Zhiqi; Ong, Peck-Hoon; Bryant, Adam L; Lo, Ngai-Nung; Clark, Ross A

2011-12-01

Knee extensor strength is an important correlate of physical function in patients with knee osteoarthritis; however, it remains unclear whether standing balance is also a correlate. The purpose of this study was to evaluate the cross-sectional associations of knee extensor strength, standing balance, and their interaction with physical function. One hundred four older adults with end-stage knee osteoarthritis awaiting a total knee replacement (mean ± SD age 67 ± 8 years) participated. Isometric knee extensor strength was measured using an isokinetic dynamometer. Standing balance performance was measured by the center of pressure displacement during quiet standing on a balance board. Physical function was measured by the self-report Short Form 36 (SF-36) questionnaire and by the 10-meter fast-pace gait speed test. After adjustment for demographic and knee pain variables, we detected significant knee strength by standing balance interaction terms for both SF-36 physical function and fast-pace gait speed. Interrogation of the interaction revealed that standing balance in the anteroposterior plane was positively related to physical function among patients with lower knee extensor strength. Conversely, among patients with higher knee extensor strength, the standing balance-physical function associations were, or tended to be, negative. These findings suggest that although standing balance was related to physical function in patients with knee osteoarthritis, this relationship was complex and dependent on knee extensor strength level. These results are of importance in developing intervention strategies and refining theoretical models, but they call for further study. Copyright © 2011 by the American College of Rheumatology.

Efficacy of massage on muscle soreness, perceived recovery, physiological restoration and physical performance in male bodybuilders.

PubMed

Kargarfard, Mehdi; Lam, Eddie T C; Shariat, Ardalan; Shaw, Ina; Shaw, Brandon S; Tamrin, Shamsul B M

2016-01-01

It is believed that sport massage after intensive exercise might improve power and perceptual recovery in athletes. However, few studies have been done in this area. This study aimed to examine the effect of massage on the performance of bodybuilders. Thirty experienced male bodybuilders were randomly assigned to either a massage group (n = 15) or a control group (n = 15). Both groups performed five repetition sets at 75-77% of 1RM of knee extensor and flexor muscle groups. The massage group then received a 30-min massage after the exercise protocol while the control group maintained their normal passive recovery. Criteria under investigation included: plasma creatine kinase (CK) level, agility test, vertical jump test, isometric torque test, and perception of soreness. All variables were measured over 6 time periods: baseline, immediately after the DOMS inducing protocol, right after the massage, and 24, 48, and 72 h after the massage. Both groups showed significant (P < .001) decreases in jumping, agility performance, and isometric torque, but significant (P < .001) increases in CK and muscle soreness levels. The massage group in general demonstrated a better recovery rate. As such, a post-exercise massage session can improve the exercise performance and recovery rate in male bodybuilders after intensive exercise.

Effect of cooling during inter-exercise periods on subsequent intramuscular water movement and muscle performance.

PubMed

Yanagisawa, O; Otsuka, S; Fukubayashi, T

2014-02-01

To evaluate the effects of cooling between exercise sessions on intramuscular water movement and muscle performance, the lower extremities of nine untrained men were assigned to either a cooling protocol (20-min water immersion, 15 °C) or a noncooling protocol. Each subject performed two exercise sessions involving maximal concentric knee extension and flexion (three repetitions, 60°/s; followed by 50 repetitions, 180°/s). The peak torque at 60°/s and total work, mean power, and decrease rate of torque value at 180°/s were evaluated. Axial magnetic resonance diffusion-weighted images of the mid-thigh were obtained before and after each exercise session. Apparent diffusion coefficient (ADC) values for the quadriceps and hamstrings were calculated for evaluating intramuscular water movement. Both groups exhibited significantly increased ADC values for the quadriceps and hamstrings after each exercise session. These ADC values returned to the pre-exercise level after water immersion. No significant difference was observed in muscle performance from first exercise session to the next in either group, except for increased total work and mean power in knee flexion in the cooled group. Cooling intervention between exercise sessions decreased exercise-induced elevation of intramuscular water movement and had some beneficial effects on muscle endurance of knee flexors, but not knee extensors. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Whole-body vibration does not influence knee joint neuromuscular function or proprioception.

PubMed

Hannah, R; Minshull, C; Folland, J P

2013-02-01

This study examined the acute effects of whole-body vibration (WBV) on knee joint position sense and indices of neuromuscular function, specifically strength, electromechanical delay and the rate of force development. Electromyography and electrically evoked contractions were used to investigate neural and contractile responses to WBV. Fourteen healthy males completed two treatment conditions on separate occasions: (1) 5 × 1 min of unilateral isometric squat exercise on a synchronous vibrating platform [30 Hz, 4 mm peak-to-peak amplitude] (WBV) and (2) a control condition (CON) of the same exercise without WBV. Knee joint position sense (joint angle replication task) and quadriceps neuromuscular function were assessed pre-, immediately-post and 1 h post-exercise. During maximum voluntary knee extensions, the peak force (PF(V)), electromechanical delay (EMD(V)), rate of force development (RFD(V)) and EMG of the quadriceps were measured. Twitch contractions of the knee extensors were electrically evoked to assess EMD(E) and RFD(E). The results showed no influence of WBV on knee joint position, EMD(V), PF(V) and RFD(V) during the initial 50, 100 or 150 ms of contraction. Similarly, electrically evoked neuromuscular function and neural activation remained unchanged following the vibration exercise. A single session of unilateral WBV did not influence any indices of thigh muscle neuromuscular performance or knee joint proprioception. © 2011 John Wiley & Sons A/S.

The Effects of Different Passive Static Stretching Intensities on Recovery from Unaccustomed Eccentric Exercise - A Randomized Controlled Trial.

PubMed

Apostolopoulos, Nikos C; Lahart, Ian M; Plyley, Michael J; Taunton, Jack; Nevill, Alan M; Koutedakis, Yiannis; Wyon, Matthew; Metsios, George S

2018-03-12

Effects of passive static stretching intensity on recovery from unaccustomed eccentric exercise of right knee extensors was investigated in 30 recreationally active males randomly allocated into three groups: high-intensity (70-80% maximum perceived stretch), low-intensity (30-40% maximum perceived stretch), and control. Both stretching groups performed 3 sets of passive static stretching exercises of 60s each for hamstrings, hip flexors, and quadriceps, over 3 consecutive days, post-unaccustomed eccentric exercise. Muscle function (eccentric and isometric peak torque) and blood biomarkers (CK and CRP) were measured before (baseline) and after (24, 48, and 72h) unaccustomed eccentric exercise. Perceived muscle soreness scores were collected immediately (time 0), and after 24, 48, and 72h post-exercise. Statistical time x condition interactions observed only for eccentric peak torque (p=.008). Magnitude-based inference analyses revealed low-intensity stretching had most likely, very likely, or likely beneficial effects on perceived muscle soreness (48-72h and 0-72h) and eccentric peak torque (baseline-24h and baseline-72h), compared with high-intensity stretching. Compared with control, low-intensity stretching had very likely or likely beneficial effects on perceived muscle soreness (0-24h and 0-72h), eccentric peak torque (baseline-48h and baseline-72h), and isometric peak torque (baseline-72h). High-intensity stretching had likely beneficial effects on eccentric peak torque (baseline-48h), but likely harmful effects eccentric peak torque (baseline-24h) and CK (baseline-48h and baseline-72h), compared with control. Therefore, low-intensity stretching is likely to result in small-to-moderate beneficial effects on perceived muscle soreness and recovery of muscle function post-unaccustomed eccentric exercise, but not markers of muscle damage and inflammation, compared with high-intensity or no stretching.

Effect of 7-days dry immersion in combination with mechanical stimulation of foot support zones upon resistance to fatigue of knee extensors and flexors

NASA Astrophysics Data System (ADS)

Netreba, A. I.; Khusnutdiniva, D. R.; Vinogradova, O. L.; Kozlovskaya, I. B.

2005-08-01

The aim of investigation was to reveal the effect of supportlessness in combination with artificial stimulation of foot support zones on fatigue resistance of knee extensors and flexors in static and rhythmic tests. 10 volunteers were exposed to 7 days dry immersion (DI). 4 of them were subjected to mechanical stimulation of foot support zones. 7-day DI did not evoke any changes in fatigue resistance during rhythmic contractions of knee extensors and flexors in both groups. Static test revealed significant decrease of fatigue resistance of both knee flexors and extensors. In the group with stimulation of support zones unfavorable effects of immersion were minimized for knee extensors but not for flexors. Thus support withdrawal is associated with a decrease of fatigue resistance for both knee flexors and extensors only under conditions of static tension. Artificial stimulation of support zones of the foot selectively affects the posture muscles.

Correlation of the Y-Balance Test with Lower-limb Strength of Adult Women

PubMed Central

Lee, Dong-Kyu; Kim, Gyoung-Mo; Ha, Sung-Min; Oh, Jae-Seop

2014-01-01

[Purpose] The purpose of this study was to elucidate the relationship between Y-balance test (YBT) distance and the lower-limb strength of adult women. [Subjects] Forty women aged 45 to 80 years volunteered for this study. [Methods] The participants were tested for maximal muscle strength of the lower limbs (hip extensors, hip flexors, hip abductors, knee extensors, knee flexors, and ankle dorsiflexors) and YBT distances in the anterior, posteromedial, and posterolateral directions. Pearson’s correlation coefficient was used to quantify the linear relationships between YBT distances and lower-limb strength. [Results] Hip extensor and knee flexor strength were positively correlated with YBT anterior distance. Hip extensor, hip abductor, and knee flexor strength were positively correlated with the YBT posteromedial distance. Hip extensor and knee flexor strength were positively correlated with YBT posterolateral distance. [Conclusion] There was a weak correlation between lower-limb strength (hip extensors, hip abductors, and knee flexors) and dynamic postural control as measured by the YBT. PMID:24926122

Neuromuscular electrical stimulation via the peroneal nerve is superior to graduated compression socks in reducing perceived muscle soreness following intense intermittent endurance exercise.

PubMed

Ferguson, Richard A; Dodd, Matthew J; Paley, Victoria R

2014-10-01

A novel technique of neuromuscular electrical stimulation (NMES) via the peroneal nerve has been shown to augment limb blood flow which could enhance recovery following exercise. The present study examined the effects of NMES, compared to graduated compression socks on muscle soreness, strength, and markers of muscle damage and inflammation following intense intermittent exercise. Twenty-one (age 21 ± 1 years, height 179 ± 7 cm, body mass 76 ± 9 kg,) healthy males performed a 90-min intermittent shuttle running test on three occasions. Following exercise, the following interventions were applied: passive recovery (CON), graduated compression socks (GCS) or NMES. Perceived muscle soreness (PMS) and muscle strength (isometric maximal voluntary contraction of knee extensors and flexors) were measured and a venous blood sample taken pre-exercise and 0, 1, 24, 48 and 72 h following exercise for measurement of creatine kinase (CK) and Lactate dehydrogenase (LDH) activity and IL-6 and CRP concentrations. PMS increased in all conditions immediately, 1 and 24 h post-exercise. At 24 h PMS was lower in NMES compared to GCS and CON (2.0 ± 1.6, 3.2 ± 2.1, 4.6 ± 2.0, respectively). At 48 h PMS was lower in NMES compared to CON (1.3 ± 1.5 and 3.1 ± 1.8, respectively). There were no differences between treatments for muscle strength, CK and LDH activity, IL-6 and CRP concentrations. The novel NMES technique is superior to GCS in reducing PMS following intense intermittent endurance exercise.

Neuromuscular Fatigue during Prolonged Exercise in Hypoxia.

PubMed

Jubeau, Marc; Rupp, Thomas; Temesi, John; Perrey, Stéphane; Wuyam, Bernard; Millet, Guillaume Y; Verges, Samuel

2017-03-01

Prolonged cycling exercise performance in normoxia is limited because of both peripheral and central neuromuscular impairments. It has been reported that cerebral perturbations are greater during short-duration exercise in hypoxia compared with normoxia. The purpose of this study was to test the hypothesis that central deficits are accentuated in hypoxia compared with normoxia during prolonged (three bouts of 80 min separated by 25 min) whole-body exercise at the same relative intensity. Ten subjects performed two sessions consisting of three 80-min cycling bouts at 45% of their relative maximal aerobic power in normoxia and hypoxia (FiO2 = 0.12). Before exercise and after each bout, maximal voluntary force, voluntary activation assessed with nerve stimulation and transcranial magnetic stimulation, corticospinal excitability (motor evoked potential), intracortical inhibition (cortical silent period), and electrical (M-wave) and contractile (twitch and doublet peak forces) properties of the knee extensors were measured. Prefrontal and motor cortical oxygenation was also recorded during each cycling bout in both conditions. A significant but similar force reduction (≈-22%) was observed at the end of exercise in normoxia and hypoxia. The modifications of voluntary activation assessed with transcranial magnetic stimulation and nerve stimulation, motor evoked potential, cortical silent period, and M-wave were also similar in both conditions. However, cerebral oxygenation was reduced in hypoxia compared with normoxia. These findings show that when performed at the same relative low intensity, prolonged exercise does not induce greater supraspinal fatigue in hypoxia compared with normoxia. Despite lower absolute exercise intensities in hypoxia, reduced brain O2 availability might contribute to similar amounts of central fatigue compared with normoxia.

Effects of low-level laser therapy applied before or after plyometric exercise on muscle damage markers: randomized, double-blind, placebo-controlled trial.

PubMed

Fritsch, Carolina Gassen; Dornelles, Maurício Pinto; Severo-Silveira, Lucas; Marques, Vanessa Bernardes; Rosso, Isabele de Albuquerque; Baroni, Bruno Manfredini

2016-12-01

Promising effects of phototherapy on markers of exercise-induced muscle damage has been already demonstrated in constant load or isokinetic protocols. However, its effects on more functional situations, such as plyometric exercises, and when is the best moment to apply this treatment (pre- or post-exercise) remain unclear. Therefore, the purpose of this study was to investigate the effect of low-level laser therapy (LLLT) before or after plyometric exercise on quadriceps muscle damage markers. A randomized, double-blinded, placebo-controlled trial was conducted with 24 healthy men, 12 at pre-exercise treatment group and 12 at post-exercise treatment group. Placebo and LLLT (810 nm, 200 mW per diode, 6 J per diode, 240 J per leg) were randomly applied on right/left knee extensor muscles of each volunteer before/after a plyometric exercise protocol. Muscular echo intensity (ultrasonography images), soreness (visual analogue scale - VAS), and strength impairment (maximal voluntary contraction - MVC) were assessed at baseline, 24, 48, and 72 h post-exercise. Legs treated with LLLT before or after exercise presented significantly smaller increments of echo intensity (values up to 1 %) compared to placebo treatments (increased up to ∼7 %). No significant treatment effect was found for VAS and MVC, although a trend toward better results on LLLT legs have been found for VAS (mean values up to 30 % lesser than placebo leg). In conclusion, LLLT applied before or after plyometric exercise reduces the muscle echo intensity response and possibly attenuates the muscle soreness. However, these positive results were not observed on strength impairment.

A Biomechanical Investigation of A Single-Limb Squat: Implications for Lower Extremity Rehabilitation Exercise

PubMed Central

Richards, Jim; Thewlis, Dominic; Selfe, James; Cunningham, Andrew; Hayes, Colin

2008-01-01

Context: Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. Objective: To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60° of knee flexion while performing a single-limb squat at different decline angles. Design: Participants acted as their own controls in a repeated-measures design. Patients or Other Participants: We recruited 10 participants who had no pain, injury, or neurologic disorder. Intervention(s): Participants performed single-limb squats at different decline angles. Main Outcome Measure(s): Angle-specific knee and ankle moments were calculated at 60° of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60° of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. Results: An increase was seen in the knee moments (P < .05) and integrated EMG in the rectus femoris (P < .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P  =  .001), but EMG activity in the gastrocnemius increased between 16° and 24° (P  =  .018). Conclusions: As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24° decline angle compared with the 16° decline angle. This indicates that decline squats at an angle greater than 16° may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee. PMID:18833310

Relationship between leg extensor muscle strength and knee joint loading during gait before and after total knee arthroplasty.

PubMed

Vahtrik, Doris; Gapeyeva, Helena; Ereline, Jaan; Pääsuke, Mati

2014-01-01

The aim of the present study was to evaluate an isometric maximal voluntary contraction (MVC) force of the leg extensor muscles and its relationship with knee joint loading during gait prior and after total knee arthroplasty (TKA). Custom-made dynamometer was used to assess an isometric MVC force of the leg extensor muscles and 3-D motion analysis system was used to evaluate the knee joint loading during gait in 13 female patients (aged 49-68 years) with knee osteoarthritis. Patients were evaluated one day before, and three and six months following TKA in the operated and non-operated leg. Six months after TKA, MVC force of the leg extensor muscles for the operated leg did not differ significantly as compared to the preoperative level, whereas it remained significantly lower for the non-operated leg and controls. The knee flexion moment and the knee joint power during mid stance of gait was improved six months after TKA, remaining significantly lowered compared with controls. Negative moderate correlation between leg extensor muscles strength and knee joint loading for the operated leg during mid stance was noted three months after TKA. The correlation analysis indicates that due to weak leg extensor muscles, an excessive load is applied to knee joint during mid stance of gait in patients, whereas in healthy subjects stronger knee-surrounding muscles provide stronger knee joint loading during gait. III (correlational study). Copyright © 2013 Elsevier B.V. All rights reserved.

Changes in Fatigue, Multiplanar Knee Laxity, and Landing Biomechanics During Intermittent Exercise

PubMed Central

Shultz, Sandra J.; Schmitz, Randy J.; Cone, John R.; Henson, Robert A.; Montgomery, Melissa M.; Pye, Michele L.; Tritsch, Amanda J.

2015-01-01

Context: Knee laxity increases during exercise. However, no one, to our knowledge, has examined whether these increases contribute to higher-risk landing biomechanics during prolonged, fatiguing exercise. Objectives: To examine associations between changes in fatigue (measured as sprint time [SPTIME]), multiplanar knee laxity (anterior-posterior [APLAX], varus-valgus [VVLAX] knee laxity, and internal-external rotation [IERLAX]) knee laxity and landing biomechanics during prolonged, intermittent exercise. Design: Descriptive laboratory study. Setting: Laboratory and gymnasium. Patients or Other Participants: A total of 30 male (age = 20.3 ± 2.0 years, height = 1.79 ± 0.05 m, mass = 75.2 ± 7.2 kg) and 29 female (age = 20.5 ± 2.3 years, height = 1.67 ± 0.08 m, mass = 61.8 ± 9.0 kg) competitive athletes. Intervention(s): A 90-minute intermittent exercise protocol (IEP) designed to simulate the physiologic and biomechanical demands of a soccer match. Main Outcome Measure(s): We measured SPTIME, APLAX, and landing biomechanics before and after warm-up, every 15 minutes during the IEP, and every 15 minutes for 1 hour after the IEP. We measured VVLAX and IERLAX before and after the warm-up, at 45 and 90 minutes during the IEP, and at 30 minutes after the IEP. We used hierarchical linear modeling to examine associations between exercise-related changes in SPTIME and knee laxity with exercise-related changes in landing biomechanics while controlling for initial (before warm-up) knee laxity. Results: We found that SPTIME had a more global effect on landing biomechanics in women than in men, resulting in a more upright landing and a reduction in landing forces and out-of-plane motions about the knee. As APLAX increased with exercise, women increased their knee internal-rotation motion (P = .02), and men increased their hip-flexion motion and energy-absorption (P = .006) and knee-extensor loads (P = .04). As VVLAX and IERLAX increased, women went through greater knee-valgus motion and dorsiflexion and absorbed more energy at the knee (P ≤ .05), whereas men were positioned in greater hip external and knee internal rotation and knee valgus throughout the landing (P = .03). The observed fatigue- and laxity-related changes in landing biomechanics during exercise often depended on initial knee laxity. Conclusions: Both exercise-related changes in fatigue and knee laxity were associated with higher-risk landing biomechanics during prolonged exercise. These relationships were more pronounced in participants with greater initial knee laxity. PMID:25674926

Vibration Therapy Is No More Effective Than the Standard Practice of Massage and Stretching for Promoting Recovery From Muscle Damage After Eccentric Exercise.

PubMed

Fuller, Joel T; Thomson, Rebecca L; Howe, Peter R C; Buckley, Jonathan D

2015-07-01

The purpose of this study was to determine if vibration therapy is more effective than the standard treatment of stretching and massage for improving recovery of muscle strength and reducing muscle soreness after muscle damage induced by eccentric exercise. A randomized, single-blinded parallel intervention trial design was used. Research laboratory. Fifty untrained men aged 18 to 30 years completed the study. Participants performed 100 maximal eccentric muscle actions (ECCmax) of the right knee extensor muscles. For the next 7 days, 25 participants applied cycloidal vibration therapy to the knee extensors twice daily and 25 participants performed stretching and sports massage (SSM) twice daily. Changes in markers of muscle damage [peak isometric torque (PIT), serum creatine kinase (CK), and serum myoglobin (Mb)], muscle soreness (visual analog scale), and inflammation [serum C-reactive protein (CRP)] were assessed. After ECCmax, there was no difference in recovery of PIT and muscle soreness or serum CK, Mb, and CRP levels between vibration and SSM groups (P > 0.28). Cycloidal vibration therapy is no more effective than the standard practice of stretching and massage to promote muscle recovery after the performance of muscle-damaging exercise. Prescription of vibration therapy after maximal exercise involving eccentric muscle damage did not alleviate signs and symptoms of muscle damage faster than the standard prescription of stretching and massage.

Relationships between explosive and maximal triple extensor muscle performance and vertical jump height.

PubMed

Chang, Eunwook; Norcross, Marc F; Johnson, Sam T; Kitagawa, Taichi; Hoffman, Mark

2015-02-01

The purpose of this study was to examine the relationships between maximum vertical jump height and (a) rate of torque development (RTD) calculated during 2 time intervals, 0-50 milliseconds (RTD50) and 0-200 milliseconds (RTD200) after torque onset and (b) peak torque (PT) for each of the triple extensor muscle groups. Thirty recreationally active individuals performed maximal isometric voluntary contractions (MVIC) of the hip, knee and ankle extensors, and a countermovement vertical jump. Rate of torque development was calculated from 0 to 50 (RTD50) and 0 to 200 (RTD200) milliseconds after the onset of joint torque. Peak torque was identified and defined as the maximum torque value during each MVIC trial. Greater vertical jump height was associated with greater knee and ankle extension RTD50, RTD200, and PT (p ≤ 0.05). However, hip extension RTD50, RTD200, and PT were not significantly related to maximal vertical jump height (p > 0.05). The results indicate that 47.6 and 32.5% of the variability in vertical jump height was explained by knee and ankle extensor RTD50, respectively. Knee and ankle extensor RTD50 also seemed to be more closely related to vertical jump performance than RTD200 (knee extensor: 28.1% and ankle extensor: 28.1%) and PT (knee extensor: 31.4% and ankle extensor: 13.7%). Overall, these results suggest that training specifically targeted to improve knee and ankle extension RTD, especially during the early phases of muscle contraction, may be effective for increasing maximal vertical jump performance.

The effect of warm-ups with stretching on the isokinetic moments of collegiate men.

PubMed

Park, Hyoung-Kil; Jung, Min-Kyung; Park, Eunkyung; Lee, Chang-Young; Jee, Yong-Seok; Eun, Denny; Cha, Jun-Youl; Yoo, Jaehyun

2018-02-01

Performing warm-ups increases muscle temperature and blood flow, which contributes to improved exercise performance and reduced risk of injuries to muscles and tendons. Stretching increases the range of motion of the joints and is effective for the maintenance and enhancement of exercise performance and flexibility, as well as for injury prevention. However, stretching as a warm-up activity may temporarily decrease muscle strength, muscle power, and exercise performance. This study aimed to clarify the effect of stretching during warm-ups on muscle strength, muscle power, and muscle endurance in a nonathletic population. The subjects of this study consisted of 13 physically active male collegiate students with no medical conditions. A self-assessment questionnaire regarding how well the subjects felt about their physical abilities was administered to measure psychological readiness before and after the warm-up. Subjects performed a non-warm-up, warm-up, or warm-up regimen with stretching prior to the assessment of the isokinetic moments of knee joints. After the measurements, the respective variables were analyzed using nonparametric tests. First, no statistically significant intergroup differences were found in the flexor and extensor peak torques of the knee joints at 60°/sec, which were assessed to measure muscle strength. Second, no statistically significant intergroup differences were found in the flexor and extensor peak torques of the knee joints at 180°/sec, which were assessed to measure muscle power. Third, the total work of the knee joints at 240°/sec, intended to measure muscle endurance, was highest in the aerobic-stretch-warm-ups (ASW) group, but no statistically significant differences were found among the groups. Finally, the psychological readiness for physical activity according to the type of warm-up was significantly higher in ASW. Simple stretching during warm-ups appears to have no effect on variables of exercise physiology in nonathletes who participate in routine recreational sport activities. However, they seem to have a meaningful effect on exercise performance by affording psychological stability, preparation, and confidence in exercise performance.

Movement-Related Cortical Potential Amplitude Reduction after Cycling Exercise Relates to the Extent of Neuromuscular Fatigue

PubMed Central

Spring, Jérôme Nicolas; Place, Nicolas; Borrani, Fabio; Kayser, Bengt; Barral, Jérôme

2016-01-01

Exercise-induced fatigue affects the motor control and the ability to generate a given force or power. Surface electroencephalography allows researchers to investigate movement-related cortical potentials (MRCP), which reflect preparatory brain activity 1.5 s before movement onset. Although the MRCP amplitude appears to increase after repetitive single-joint contractions, the effects of large-muscle group dynamic exercise on such pre-motor potential remain to be described. Sixteen volunteers exercised 30 min at 60% of the maximal aerobic power on a cycle ergometer, followed by a 10-km all-out time trial. Before and after each of these tasks, knee extensor neuromuscular function was investigated using maximal voluntary contractions (MVC) combined with electrical stimulations of the femoral nerve. MRCP was recorded during 60 knee extensions after each neuromuscular sequence. The exercise resulted in a significant decrease in the knee extensor MVC force after the 30-min exercise (−10 ± 8%) and the time trial (−21 ± 9%). The voluntary activation level (VAL; −6 ± 8 and −12 ± 10%), peak twitch (Pt; −21 ± 16 and −32 ± 17%), and paired stimuli (P100 Hz; −7 ± 11 and −12 ± 13%) were also significantly reduced after the 30-min exercise and the time trial. The first exercise was followed by a decrease in the MRCP, mainly above the mean activity measured at electrodes FC1-FC2, whereas the reduction observed after the time trial was related to the FC1-FC2 and C2 electrodes. After both exercises, the reduction in the late MRCP component above FC1-FC2 was significantly correlated with the reduction in P100 Hz (r = 0.61), and the reduction in the same component above C2 was significantly correlated with the reduction in VAL (r = 0.64). In conclusion, large-muscle group exercise induced a reduction in pre-motor potential, which was related to muscle alterations and resulted in the inability to produce a maximal voluntary contraction. PMID:27313522

Whole-body vibration and the prevention and treatment of delayed-onset muscle soreness.

PubMed

Aminian-Far, Atefeh; Hadian, Mohammad-Reza; Olyaei, Gholamreza; Talebian, Saeed; Bakhtiary, Amir Hoshang

2011-01-01

Numerous recovery strategies have been used in an attempt to minimize the symptoms of delayed-onset muscle soreness (DOMS). Whole-body vibration (WBV) has been suggested as a viable warm-up for athletes. However, scientific evidence to support the protective effects of WBV training (WBVT) on muscle damage is lacking. To investigate the acute effect of WBVT applied before eccentric exercise in the prevention of DOMS. Randomized controlled trial. University laboratory. A total of 32 healthy, untrained volunteers were randomly assigned to either the WBVT (n  =  15) or control (n  =  17) group. Volunteers performed 6 sets of 10 maximal isokinetic (60°/s) eccentric contractions of the dominant-limb knee extensors on a dynamometer. In the WBVT group, the training was applied using a vibratory platform (35 Hz, 5 mm peak to peak) with 100° of knee flexion for 60 seconds before eccentric exercise. No vibration was applied in the control group. Muscle soreness, thigh circumference, and pressure pain threshold were recorded at baseline and at 1, 2, 3, 4, 7, and 14 days postexercise. Maximal voluntary isometric and isokinetic knee extensor strength were assessed at baseline, immediately after exercise, and at 1, 2, 7, and 14 days postexercise. Serum creatine kinase was measured at baseline and at 1, 2, and 7 days postexercise. The WBVT group showed a reduction in DOMS symptoms in the form of less maximal isometric and isokinetic voluntary strength loss, lower creatine kinase levels, and less pressure pain threshold and muscle soreness (P < .05) compared with the control group. However, no effect on thigh circumference was evident (P < .05). Administered before eccentric exercise, WBVT may reduce DOMS via muscle function improvement. Further investigation should be undertaken to ascertain the effectiveness of WBVT in attenuating DOMS in athletes.

Muscle metabolism and activation heterogeneity by combined 31P chemical shift and T2 imaging, and pulmonary O2 uptake during incremental knee-extensor exercise

PubMed Central

Cannon, Daniel T.; Howe, Franklyn A.; Whipp, Brian J.; Ward, Susan A.; McIntyre, Dominick J.; Ladroue, Christophe; Griffiths, John R.; Kemp, Graham J.

2013-01-01

The integration of skeletal muscle substrate depletion, metabolite accumulation, and fatigue during large muscle-mass exercise is not well understood. Measurement of intramuscular energy store degradation and metabolite accumulation is confounded by muscle heterogeneity. Therefore, to characterize regional metabolic distribution in the locomotor muscles, we combined 31P magnetic resonance spectroscopy, chemical shift imaging, and T2-weighted imaging with pulmonary oxygen uptake during bilateral knee-extension exercise to intolerance. Six men completed incremental tests for the following: 1) unlocalized 31P magnetic resonance spectroscopy; and 2) spatial determination of 31P metabolism and activation. The relationship of pulmonary oxygen uptake to whole quadriceps phosphocreatine concentration ([PCr]) was inversely linear, and three of four knee-extensor muscles showed activation as assessed by change in T2. The largest changes in [PCr], [inorganic phosphate] ([Pi]) and pH occurred in rectus femoris, but no voxel (72 cm3) showed complete PCr depletion at exercise cessation. The most metabolically active voxel reached 11 ± 9 mM [PCr] (resting, 29 ± 1 mM), 23 ± 11 mM [Pi] (resting, 7 ± 1 mM), and a pH of 6.64 ± 0.29 (resting, 7.08 ± 0.03). However, the distribution of 31P metabolites and pH varied widely between voxels, and the intervoxel coefficient of variation increased between rest (∼10%) and exercise intolerance (∼30–60%). Therefore, the limit of tolerance was attained with wide heterogeneity in substrate depletion and fatigue-related metabolite accumulation, with extreme metabolic perturbation isolated to only a small volume of active muscle (<5%). Regional intramuscular disturbances are thus likely an important requisite for exercise intolerance. How these signals integrate to limit muscle power production, while regional “recruitable muscle” energy stores are presumably still available, remains uncertain. PMID:23813534

Knee Extensor Strength and Risk of Structural, Symptomatic, and Functional Decline in Knee Osteoarthritis: A Systematic Review and Meta-Analysis.

PubMed

Culvenor, Adam G; Ruhdorfer, Anja; Juhl, Carsten; Eckstein, Felix; Øiestad, Britt Elin

2017-05-01

To perform a systematic review and meta-analysis on the association between knee extensor strength and the risk of structural, symptomatic, or functional deterioration in individuals with or at risk of knee osteoarthritis (KOA). We systematically identified and methodologically appraised all longitudinal studies (≥1-year followup) reporting an association between knee extensor strength and structural (tibiofemoral, patellofemoral), symptomatic (self-reported, knee replacement), or functional (subjective, objective) decline in individuals with or at risk of radiographic or symptomatic KOA. Results were pooled for each of the above associations using meta-analysis, or if necessary, summarized according to a best-evidence synthesis. Fifteen studies were included, evaluating >8,000 participants (51% female), with a followup time between 1.5 and 8 years. Meta-analysis revealed that lower knee extensor strength was associated with an increased risk of symptomatic (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] pain: odds ratio [OR] 1.35, 95% confidence interval [95% CI] 1.10-1.67) and functional decline (WOMAC function: OR 1.38, 95% CI 1.00-1.89, and chair-stand task: OR 1.03, 95% CI 1.03-1.04), but not increased risk of radiographic tibiofemoral joint space narrowing (JSN) (OR 1.15, 95% CI 0.84-1.56). No trend in risk was observed for KOA status (present versus absent). Best-evidence synthesis showed inconclusive evidence for lower knee extensor strength being associated with increased risk of patellofemoral deterioration. Meta-analysis showed that lower knee extensor strength is associated with an increased risk of symptomatic and functional deterioration, but not tibiofemoral JSN. The risk of patellofemoral deterioration in the presence of knee extensor strength deficits is inconclusive. © 2016, American College of Rheumatology.

Salvage of the lower limb after a full thickness burn with loss of the knee extensor mechanism: a case report.

PubMed

Sarraf, Khaled M; Atherton, Duncan D; Jayaweera, Asantha R; Gibbons, Charles E; Jones, Isabel

2013-04-01

We report on a 79-year-old woman who underwent salvage of the knee and lower leg using a Whichita Fusion Nail for knee arthrodesis, combined with a medial gastrocnemius muscle flap for a 3% contact burn that resulted in loss of the extensor mechanism. This provided an alternative to above-knee amputation when extensor mechanism reconstruction was not feasible.

A study on muscle activity and ratio of the knee extensor depending on the types of squat exercise

PubMed Central

Kang, Jeong-Il; Park, Joon-Su; Choi, Hyun; Jeong, Dae-Keun; Kwon, Hye-Min; Moon, Young-Jun

2017-01-01

[Purpose] For preventing the patellofemoral pain syndrome, this study aims to suggest a proper squat method, which presents selective muscle activity of Vastus Medialis Oblique and muscle activity ratios of Vastus Medialis Oblique/Vastus Lateralis by applying squat that is a representative weight bearing exercise method in various ways depending on the surface conditions and knee bending angles. [Subjects and Methods] An isometric squat that was accompanied by hip adduction, depending on the surface condition and the knee joint flexion angle, was performed by 24 healthy students. The muscle activity and the ratio of muscle activity were measured. [Results] In a comparison of muscle activity depending on the knee joint flexion angle on a weight-bearing surface, the vastus medialis oblique showed a significant difference at 15° and 60°. Meanwhile, in a comparison of the muscle activity ratio between the vastus medialis oblique and the vastus lateralis depending on the knee joint flexion angle on a weight-bearing surface, significant differences were observed at 15° and 60°. [Conclusion] An efficient squat exercise posture for preventing the patellofemoral pain syndrome is to increase the knee joint bending angle on a stable surface. But it would be efficient for patients with difficulties in bending the knee joint to keep a knee joint bending angle of 15 degrees or less on an unstable surface. It is considered that in future, diverse studies on selective Vastus Medialis Oblique strengthening exercise methods would be needed after applying them to patients with the patellofemoral pain syndrome. PMID:28210036

Measurement of fatigue in knee flexor and extensor muscles.

PubMed

Kawabata, Y; Senda, M; Oka, T; Yagata, Y; Takahara, Y; Nagashima, H; Inoue, H

2000-04-01

In order to examine fatigue of the knee flexor and extensor muscles and to investigate the characteristics of muscular fatigue in different sports, a Cybex machine was used to measure muscle fatigue and recovery during isokinetic knee flexion and extension. Eighteen baseball players, 12 soccer players and 13 marathon runners were studied. Each subject was tested in the sitting position and made to perform 50 consecutive right knee bends and stretches at maximum strength. This was done 3 times with an interval of 10 min between each series. The peak torque to body weight ratio and the fatigue rate were determined in each case. In all subjects, the peak torque to body weight ratio was higher for extensors than flexors. Over the 3 trials, the fatigue rate of extensors showed little change, while that of flexors had a tendency to increase. In each subject, knee extensors showed a high fatigue rate but a quick recovery, while knee flexors showed a low fatigue rate but a slow recovery. As the marathon runners had the smallest fatigue rates for both flexors and extensors, we concluded that marathon runners had more stamina than baseball players and soccer players.

Knee Extensor Strength and Gait Characteristics After Minimally Invasive Unicondylar Knee Arthroplasty vs Minimally Invasive Total Knee Arthroplasty: A Nonrandomized Controlled Trial.

PubMed

Braito, Matthias; Giesinger, Johannes M; Fischler, Stefan; Koller, Arnold; Niederseer, David; Liebensteiner, Michael C

2016-08-01

In light of the existing lack of evidence, it was the aim of this study to compare gait characteristics and knee extensor strength after medial unicondylar knee arthroplasty (MUKA) with those after total knee arthroplasty (TKA), given the same standardized minimally invasive surgery (MIS) approach in both groups. Patients scheduled for MIS-MUKA or MIS-TKA as part of clinical routine were invited to participate. A posterior cruciate ligament-retaining total knee design was used for all MIS-TKA. A 3-dimensional gait analysis was performed preoperatively with a VICON system and at 8 weeks postoperative to determine temporospatial parameters, ground reaction forces, joint angles, and joint moments. At the same 2 times, isokinetic tests were performed to obtain peak values of knee extensor torque. A multivariate analysis of variance was conducted and included the main effects time (before and after surgery) and surgical group and the group-by-time interaction effect. Fifteen MIS-MUKA patients and 17 MIS-TKA patients were eligible for the final analysis. The groups showed no differences regarding age, body mass index, sex, side treated, or stage of osteoarthritis. We determined neither intergroup differences nor time × group interactions for peak knee extensor torque or any gait parameters (temporospatial, ground reaction forces, joint angles, and joint moments). It is concluded that MUKA is not superior to TKA with regard to knee extensor strength or 3-dimensional gait characteristics at 8 weeks after operation. As gait characteristics and knee extensor strength are only 2 of the various potential outcome parameters (knee scores, activity scores…) and quadriceps strength might take a longer time to recover, our findings should be interpreted with caution. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Hip posterolateral musculature strengthening in sedentary women with patellofemoral pain syndrome: a randomized controlled clinical trial with 1-year follow-up.

PubMed

Fukuda, Thiago Yukio; Melo, William Pagotti; Zaffalon, Bruno Marcos; Rossetto, Flavio Marcondes; Magalhães, Eduardo; Bryk, Flavio Fernandes; Martin, Robroy L

2012-10-01

Randomized controlled trial. To determine if adding hip-strengthening exercises to a conventional knee exercise program produces better long-term outcomes than conventional knee exercises alone in women with patellofemoral pain syndrome (PFPS). Recent studies have shown that a hip-strengthening program reduces pain and improves function in individuals with PFPS. However, there are no clinical trials evaluating long-term outcomes of this type of program compared to conventional knee-strengthening and -stretching exercises. Fifty-four sedentary women between 20 and 40 years of age, with a diagnosis of unilateral PFPS, were randomly assigned knee exercise (KE) or knee and hip exercise (KHE). The women in the KE group (n = 26; mean age, 23 years) performed a 4-week conventional knee-stretching and -strengthening program. The women in the KHE group (n = 28; mean age, 22 years) performed the same exercises as those in the KE group, as well as strengthening exercises for the hip abductors, lateral rotators, and extensors. An 11-point numeric pain rating scale, the Lower Extremity Functional Scale, the Anterior Knee Pain Scale, and a single-hop test were used as outcome measures at baseline (pretreatment) and 3, 6, and 12 months posttreatment. At baseline, demographic, pain, and functional assessment data were similar between groups. Those in the KHE group had a higher level of function and less pain at 3, 6, and 12 months compared to baseline (P<.05). In contrast, the KE group had reduced pain only at the 3- and 6-month follow-ups (P<.05), without any changes in Lower Extremity Functional Scale, Anterior Knee Pain Scale, or hop testing (P>.05) through the course of the study. Compared to the KE group, the KHE group had less pain and better function at 3, 6, and 12 months posttreatment (P<.05). For the Lower Extremity Functional Scale, the between-group difference in change scores from baseline at 3, 6, and 12 months posttreatment favored the KHE group by 22.0, 22.0, and 20.8 points, respectively. Knee-stretching and -strengthening exercises supplemented by hip posterolateral musculature-strengthening exercises were more effective than knee exercises alone in improving long-term function and reducing pain in sedentary women with PFPS.

Exercise for haemophilia.

PubMed

Strike, Karen; Mulder, Kathy; Michael, Rojer

2016-12-19

Haemophilia is a bleeding disorder associated with haemorrhaging into joints and muscles. Exercise is often used to aid recovery after bleeds, and to improve joint function in the presence of arthropathy. Our objective was to systematically review the available evidence on the safety and effectiveness of exercise for people with haemophilia. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register and electronic databases PubMed, OVID-Embase, and CINAHL. We hand searched abstracts from congresses of the World Federation of Hemophilia and the European Hematology Association, trial registries and the reference lists of relevant articles.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register: 14 December 2016. Randomized or quasi-randomized controlled studies comparing any exercise intervention considered relevant in haemophilia management including supervised, unsupervised, aquatic, strengthening, aerobic or cardiovascular, stretching, proprioceptive and balance training exercise programs in males of any age with haemophilia A or B of any severity (those with co-morbidities were not excluded). Two authors reviewed the identified abstracts to determine their eligibility. For studies meeting the inclusion criteria, full articles were obtained. The two authors extracted data and assessed the risk of bias. Any disagreements were resolved by discussion. The authors contacted study investigators to obtain any missing data. Eight studies were included, which represented 233 males with all severities of haemophilia A and B, ranging in age from eight years to 49 years. Study duration ranged from four to 12 weeks. Exercise interventions varied greatly and included resistance exercises, isometric exercises, bicycle ergometry, treadmill walking and hydrotherapy; therefore, comparison between studies was difficult.None of the studies measured or reported adverse effects from the interventions. None of the studies reported outcomes regarding bleed frequency, quality of life or aerobic activity. Overall risk of bias across all studies was assessed as unclear.Very few studies provided sufficient information for comparison. None of the studies reported data that favoured the control group. One study reported that six weeks of resistance training improved joint health status (Colorado score) compared to controls. The addition of pulsed electromagnetic fields also improved ankle scores compared to exercises alone, but this was not seen in the elbows or knees.Two studies reported statistically significant improvements in pain intensity after exercise interventions compared to controls. Hydrotherapy exercises produced significant decreases in pain compared to controls and land-based exercise groups.Two studies found improvement in joint motion in the exercise group compared to controls. One study compared land- and water-based exercises; there was no difference in the range of motion between the two groups; however, the water-based exercise group did show improvement over the control group.One study, comparing joint traction and proprioceptive neuromuscular facilitation for the elbow to a control group, showed no differences in biceps girth or strength after 12 weeks of intervention.Some studies reported comparisons between interventions. In one study, treadmill training significantly improved balance in children compared to bicycle ergometry. Another study added partial weight bearing exercises to quadriceps exercises and showed improved walking tolerance.Four studies evaluated quadriceps or hamstring strength (or both). The addition of bicycle ergometry and exercises with weights was more effective than static exercises and treadmill walking for strengthening knee flexors and extensors. Partial weight-bearing exercises through range were more effective than static and short arc exercises for improving knee extensor strength. The addition of treadmill walking to ultrasound, stretching and strengthening exercises showed increased peak torque of knee flexors and extensors and decrease in knee effusion.The results should be interpreted with caution due to the quality of evidence (GRADE) as outlined in the summary of findings tables, which demonstrates that all but one of the outcomes assessed were rated as low or very low due to the small sample sizes and potential bias. These results must be considered with caution. There is a lack of confidence in the results due to the small number of included studies and the inability to pool the results due to the heterogeneity of outcome measures. Most exercise interventions produced improvement in one or more of the measured outcomes including pain, range of motion, strength and walking tolerance. Hydrotherapy may be more effective than land exercises for pain relief in adults. Functional exercises such as treadmill walking and partial weight bearing exercises seem to be more effective than static or short arc exercises for improving muscle strength. These findings are consistent with the many non-controlled intervention reports in the haemophilia literature. No adverse effects were reported as a result of any of the interventions. However, some groups used prophylactic factor prior to exercise and other groups studied only subjects with moderate haemophilia. Therefore, the safety of these techniques for persons with severe haemophilia remains unclear.

[Does transcutaneous electrical nerve stimulation or therapeutic ultrasound increase the effectiveness of exercise for knee osteoarthritis: a randomized controlled study].

PubMed

Eyigör, Sibel; Karapolat, Hale; Ibisoğlu, Uğur; Durmaz, Berrin

2008-01-01

The aim of this study was to determine if transcutaneous electrical nerve stimulation (TENS) or therapeutic ultrasound (US) increase the effectiveness of exercise on pain, function, muscle strength and quality of life for knee osteoarthritis (OA). Forty-five patients with primary knee OA diagnosis according to American College Rheumatology criteria were sequentially divided into 3 random groups. The patients in group 1 received TENS (with superficial heat and exercise), group 2 received US (with superficial heat and exercise), and group 3 acted as controls (superficial heat and exercise). Outcome measures were included as visual analog scale (VAS), a 20-meter walking test, Lequesne index, WOMAC scores, isokinetic muscle testing, and the Short Form 36 (SF 36). All treatment groups, physical modalities were carried out for a total fifteen sessions. All of the patients were subjected to six weeks of exercise program. All of the treatment groups had significant improvement on activity VAS, 20 meter walking test, Lequesne index, WOMAC scores, and most of the sub-scores of SF36 when compared with their initial status (p<0.05). All of the treatment groups, a significant muscle strength gain in most of the angular velocity in knee extensor PT values after the treatment (p<0.05). However there was no statistically significant difference after the treatment between the all treatment groups (p>0.05). All of the treatment groups were effective on pain, function, muscle strength and quality of life in patients with knee OA. Statistically significant differences could not be found between the treatment groups. The exercise program, as it is cheaper, more easily performed and efficient, may be preferable for the treatment of knee OA. It is difficult to say, TENS or US could increase the effectiveness of isokinetic exercise for pain, function, muscle strength and quality of life of knee OA in this study.

The effect of open kinetic chain knee extensor resistance training at different training loads on anterior knee laxity in the uninjured.

PubMed

Barcellona, Massimo G; Morrissey, Matthew C

2016-04-01

The commonly used open kinetic chain knee extensor (OKCKE) exercise loads the sagittal restraints to knee anterior tibial translation. To investigate the effect of different loads of OKCKE resistance training on anterior knee laxity (AKL) in the uninjured knee. non-clinical trial. Randomization into one of three supervised training groups occurred with training 3 times per week for 12 weeks. Subjects in the LOW and HIGH groups performed OKCKE resistance training at loads of 2 sets of 20 repetition maximum (RM) and 20 sets of 2RM, respectively. Subjects in the isokinetic training group (ISOK) performed isokinetic OKCKE resistance training using 2 sets of 20 maximal efforts. AKL was measured using the KT2000 arthrometer with concurrent measurement of lateral hamstrings muscle activity at baseline, 6 weeks and 12 weeks. Twenty six subjects participated (LOW n = 9, HIGH n = 10, ISOK n = 7). The main finding from this study is that a 12-week OKCKE resistance training programme at loads of 20 sets of 2RM, leads to an increase in manual maximal AKL. OKCKE resistance training at high loads (20 sets of 2RM) increases AKL while low load OKCKE resistance training (2 sets of 20RM) and isokinetic OKCKE resistance training at 2 sets of 20RM does not. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hemodynamic responses to small muscle mass exercise in heart failure patients with reduced ejection fraction

PubMed Central

Barrett-O'Keefe, Zachary; Lee, Joshua F.; Berbert, Amanda; Witman, Melissa A. H.; Nativi-Nicolau, Jose; Stehlik, Josef; Richardson, Russell S.

2014-01-01

To better understand the mechanisms responsible for exercise intolerance in heart failure with reduced ejection fraction (HFrEF), the present study sought to evaluate the hemodynamic responses to small muscle mass exercise in this cohort. In 25 HFrEF patients (64 ± 2 yr) and 17 healthy, age-matched control subjects (64 ± 2 yr), mean arterial pressure (MAP), cardiac output (CO), and limb blood flow were examined during graded static-intermittent handgrip (HG) and dynamic single-leg knee-extensor (KE) exercise. During HG exercise, MAP increased similarly between groups. CO increased significantly (+1.3 ± 0.3 l/min) in the control group, but it remained unchanged across workloads in HFrEF patients. At 15% maximum voluntary contraction (MVC), forearm blood flow was similar between groups, while HFrEF patients exhibited an attenuated increase at the two highest intensities compared with controls, with the greatest difference at the highest workload (352 ± 22 vs. 492 ± 48 ml/min, HFrEF vs. control, 45% MVC). During KE exercise, MAP and CO increased similarly across work rates between groups. However, HFrEF patients exhibited a diminished leg hyperemic response across all work rates, with the most substantial decrement at the highest intensity (1,842 ± 64 vs. 2,675 ± 81 ml/min; HFrEF vs. control, 15 W). Together, these findings indicate a marked attenuation in exercising limb perfusion attributable to impairments in peripheral vasodilatory capacity during both arm and leg exercise in patients with HFrEF, which likely plays a role in limiting exercise capacity in this patient population. PMID:25260608

Low level laser therapy before eccentric exercise reduces muscle damage markers in humans.

PubMed

Baroni, Bruno Manfredini; Leal Junior, Ernesto Cesar Pinto; De Marchi, Thiago; Lopes, André Luiz; Salvador, Mirian; Vaz, Marco Aurélio

2010-11-01

The purpose of the present study was to determine the effect of low level laser therapy (LLLT) treatment before knee extensor eccentric exercise on indirect markers of muscle damage. Thirty-six healthy men were randomized in LLLT group (n = 18) and placebo group (n = 18). After LLLT or placebo treatment, subjects performed 75 maximal knee extensors eccentric contractions (five sets of 15 repetitions; velocity = 60° seg(-1); range of motion = 60°). Muscle soreness (visual analogue scale--VAS), lactate dehydrogenase (LDH) and creatine kinase (CK) levels were measured prior to exercise, and 24 and 48 h after exercise. Muscle function (maximal voluntary contraction--MVC) was measured before exercise, immediately after, and 24 and 48 h post-exercise. Groups had no difference on kineanthropometric characteristics and on eccentric exercise performance. They also presented similar baseline values of VAS (0.00 mm for LLLT and placebo groups), LDH (LLLT = 186 IU/l; placebo = 183 IU/l), CK (LLLT = 145 IU/l; placebo = 155 IU/l) and MVC (LLLT = 293 Nm; placebo = 284 Nm). VAS data did not show group by time interaction (P = 0.066). In the other outcomes, LLLT group presented (1) smaller increase on LDH values 48 h post-exercise (LLLT = 366 IU/l; placebo = 484 IU/l; P = 0.017); (2) smaller increase on CK values 24 h (LLLT = 272 IU/l; placebo = 498 IU/l; P = 0.020) and 48 h (LLLT = 436 IU/l; placebo = 1328 IU/l; P < 0.001) post-exercise; (3) smaller decrease on MVC immediately after exercise (LLLT = 189 Nm; placebo = 154 Nm; P = 0.011), and 24 h (LLLT = 249 Nm; placebo = 205 Nm; P = 0.004) and 48 h (LLLT = 267 Nm; placebo = 216 Nm; P = 0.001) post-exercise compared with the placebo group. In conclusion, LLLT treatment before eccentric exercise was effective in terms of attenuating the increase of muscle proteins in the blood serum and the decrease in muscle force.

The effect of the training with the different combinations of frequency and peak-to-peak vibration displacement of whole-body vibration on the strength of knee flexors and extensors

PubMed Central

Król, P; Sobota, G; Polak, A; Bacik, B; Juras, G

2017-01-01

Whole-body vibration training has become a popular method used in sports and physiotherapy. The study aimed to evaluate the effect of different vibration frequency and peak-to-peak displacement combinations on men knee flexors and extensors strength in isokinetic conditions. The sample consisted of 49 male subjects randomly allocated to seven comparative groups, six of which exercised on a vibration platform with parameters set individually for the groups. The experimental groups were exposed to vibrations 3 times a week for 4 weeks. The pre- and post- isokinetic strength tests, with the angular velocities of 240°/s and 30°/s, were recorded prior to and 2 days after the training. After 4 weeks of whole-body vibration training, a significant increase was noted regarding the mean values of peak torque, average peak torque and total work for knee flexors at high angular velocity in Groups I (60 Hz/4 mm) and V (40 Hz/2 mm) (p<0.05). The mean percentage values of post-training changes to study parameters suggest that the training had the most beneficial effect in Groups I (60 Hz/4 mm) and IV (60 Hz/2 mm) (p<0.05). Whole-body vibrations during static exercise beneficially affected knee flexor strength profile in young men at high angular velocity. The combinations of 60 Hz/4 mm seem to have the most advantageous effects on muscle strength parameters. PMID:28566806

Low- Versus High-Intensity Plyometric Exercise During Rehabilitation After Anterior Cruciate Ligament Reconstruction.

PubMed

Chmielewski, Terese L; George, Steven Z; Tillman, Susan M; Moser, Michael W; Lentz, Trevor A; Indelicato, Peter A; Trumble, Troy N; Shuster, Jonathan J; Cicuttini, Flavia M; Leeuwenburgh, Christiaan

2016-03-01

Plyometric exercise is used during rehabilitation after anterior cruciate ligament (ACL) reconstruction to facilitate the return to sports participation. However, clinical outcomes have not been examined, and high loads on the lower extremity could be detrimental to knee articular cartilage. To compare the immediate effect of low- and high-intensity plyometric exercise during rehabilitation after ACL reconstruction on knee function, articular cartilage metabolism, and other clinically relevant measures. Randomized controlled trial; Level of evidence, 2. Twenty-four patients who underwent unilateral ACL reconstruction (mean, 14.3 weeks after surgery; range, 12.1-17.7 weeks) were assigned to 8 weeks (16 visits) of low- or high-intensity plyometric exercise consisting of running, jumping, and agility activities. Groups were distinguished by the expected magnitude of vertical ground-reaction forces. Testing was conducted before and after the intervention. Primary outcomes were self-reported knee function (International Knee Documentation Committee [IKDC] subjective knee form) and a biomarker of articular cartilage degradation (urine concentrations of crosslinked C-telopeptide fragments of type II collagen [uCTX-II]). Secondary outcomes included additional biomarkers of articular cartilage metabolism (urinary concentrations of the neoepitope of type II collagen cleavage at the C-terminal three-quarter-length fragment [uC2C], serum concentrations of the C-terminal propeptide of newly formed type II collagen [sCPII]) and inflammation (tumor necrosis factor-α), functional performance (maximal vertical jump and single-legged hop), knee impairments (anterior knee laxity, average knee pain intensity, normalized quadriceps strength, quadriceps symmetry index), and psychosocial status (kinesiophobia, knee activity self-efficacy, pain catastrophizing). The change in each measure was compared between groups. Values before and after the intervention were compared with the groups combined. The groups did not significantly differ in the change of any primary or secondary outcome measure. Of interest, sCPII concentrations tended to change in opposite directions (mean ± SD: low-intensity group, 28.7 ± 185.5 ng/mL; high-intensity group, -200.6 ± 255.0 ng/mL; P = .097; Cohen d = 1.03). Across groups, significant changes after the intervention were increased the IKDC score, vertical jump height, normalized quadriceps strength, quadriceps symmetry index, and knee activity self-efficacy and decreased average knee pain intensity. No significant differences were detected between the low- and high-intensity plyometric exercise groups. Across both groups, plyometric exercise induced positive changes in knee function, knee impairments, and psychosocial status that would support the return to sports participation after ACL reconstruction. The effect of plyometric exercise intensity on articular cartilage requires further evaluation. Clinicaltrials.gov NCT01851655. © 2016 The Author(s).

Chain-loaded variable resistance warm-up improves free-weight maximal back squat performance.

PubMed

Mina, Minas A; Blazevich, Anthony J; Giakas, Giannis; Seitz, Laurent B; Kay, Anthony D

2016-11-01

The acute influence of chain-loaded variable resistance exercise on subsequent free-weight one-repetition maximum (1-RM) back squat performance was examined in 16 recreationally active men. The participants performed either a free-weight resistance (FWR) or chain-loaded resistance (CLR) back squat warm-up at 85% 1-RM on two separate occasions. After a 5-min rest, the participants attempted a free-weight 1-RM back squat; if successful, subsequent 5% load additions were made until participants failed to complete the lift. During the 1-RM trials, 3D knee joint kinematics and knee extensor and flexor electromyograms (EMG) were recorded simultaneously. Significantly greater 1-RM (6.2 ± 5.0%; p < .01) and mean eccentric knee extensor EMG (32.2 ± 6.7%; p < .01) were found after the CLR warm-up compared to the FWR condition. However, no difference (p > .05) was found in concentric EMG, eccentric or concentric knee angular velocity, or peak knee flexion angle. Performing a CLR warm-up enhanced subsequent free-weight 1-RM performance without changes in knee flexion angle or eccentric and concentric knee angular velocities; thus a real 1-RM increase was achieved as the mechanics of the lift were not altered. These results are indicative of a potentiating effect of CLR in a warm-up, which may benefit athletes in tasks where high-level strength is required.

Dynamic water exercise in individuals with late poliomyelitis.

PubMed

Willén, C; Sunnerhagen, K S; Grimby, G

2001-01-01

To evaluate the specific effects of general dynamic water exercise in individuals with late effects of poliomyelitis. Before-after tests. A university hospital department. Twenty-eight individuals with late effects of polio, 15 assigned to the training group (TG) and 13 to the control group (CG). The TG completed a 40-minute general fitness training session in warm water twice weekly. Assessment instruments included the bicycle ergometer test, isokinetic muscle strength, a 30-meter walk indoors, Berg balance scale, a pain drawing, a visual analog scale, the Physical Activity Scale for the Elderly, and the Nottingham Health Profile (NHP). Peak load, peak work load, peak oxygen uptake, peak heart rate (HR), muscle function in knee extensors and flexors, and pain dimension of the NHP. The average training period was 5 months; compliance was 75% (range, 55-98). No negative effects were seen. The exercise did not influence the peak work load, peak oxygen uptake, or muscle function in knee extensors compared with the controls. However, a decreased HR at the same individual work load was seen, as well as a significantly lower distress in the dimension pain of the NHP. Qualitative aspects such as increased well-being, pain relief, and increased physical fitness were reported. A program of nonswimming dynamic exercises in heated water has a positive impact on individuals with late effects of polio, with a decreased HR at exercise, less pain, and a subjective positive experience. The program was well tolerated (no adverse effects were reported) and can be recommended for this group of individuals.

Loss of knee extensor torque complexity during fatiguing isometric muscle contractions occurs exclusively above the critical torque.

PubMed

Pethick, Jamie; Winter, Samantha L; Burnley, Mark

2016-06-01

The complexity of knee extensor torque time series decreases during fatiguing isometric muscle contractions. We hypothesized that because of peripheral fatigue, this loss of torque complexity would occur exclusively during contractions above the critical torque (CT). Nine healthy participants performed isometric knee extension exercise (6 s of contraction, 4 s of rest) on six occasions for 30 min or to task failure, whichever occurred sooner. Four trials were performed above CT (trials S1-S4, S1 being the lowest intensity), and two were performed below CT (at 50% and 90% of CT). Global, central, and peripheral fatigue were quantified using maximal voluntary contractions (MVCs) with femoral nerve stimulation. The complexity of torque output was determined using approximate entropy (ApEn) and the detrended fluctuation analysis-α scaling exponent (DFA-α). The MVC torque was reduced in trials below CT [by 19 ± 4% (means ± SE) in 90%CT], but complexity did not decrease [ApEn for 90%CT: from 0.82 ± 0.03 to 0.75 ± 0.06, 95% paired-samples confidence intervals (CIs), 95% CI = -0.23, 0.10; DFA-α from 1.36 ± 0.01 to 1.32 ± 0.03, 95% CI -0.12, 0.04]. Above CT, substantial reductions in MVC torque occurred (of 49 ± 8% in S1), and torque complexity was reduced (ApEn for S1: from 0.67 ± 0.06 to 0.14 ± 0.01, 95% CI = -0.72, -0.33; DFA-α from 1.38 ± 0.03 to 1.58 ± 0.01, 95% CI 0.12, 0.29). Thus, in these experiments, the fatigue-induced loss of torque complexity occurred exclusively during contractions performed above the CT. Copyright © 2016 the American Physiological Society.

Relationships between Isometric Muscle Strength, Gait Parameters, and Gross Motor Function Measure in Patients with Cerebral Palsy

PubMed Central

Shin, Hyung-Ik; Sung, Ki Hyuk; Chung, Chin Youb; Lee, Kyoung Min; Lee, Seung Yeol; Lee, In Hyeok

2016-01-01

Purpose This study investigated the correlation between isometric muscle strength, gross motor function, and gait parameters in patients with spastic cerebral palsy and to find which muscle groups play an important role for gait pattern in a flexed knee gait. Materials and Methods Twenty-four ambulatory patients (mean age, 10.0 years) with spastic cerebral palsy who were scheduled for single event multilevel surgery, including distal hamstring lengthening, were included. Preoperatively, peak isometric muscle strength was measured for the hip flexor, hip extensor, knee flexor, and knee extensor muscle groups using a handheld dynamometer, and three-dimensional (3D) gait analysis and gross motor function measure (GMFM) scoring were also performed. Correlations between peak isometric strength and GMFM, gait kinematics, and gait kinetics were analyzed. Results Peak isometric muscle strength of all muscle groups was not related to the GMFM score and the gross motor function classification system level. Peak isometric strength of the hip extensor and knee extensor was significantly correlated with the mean pelvic tilt (r=-0.588, p=0.003 and r=-0.436, p=0.033) and maximum pelvic obliquity (r=-0.450, p=0.031 and r=-0.419, p=0.041). There were significant correlations between peak isometric strength of the knee extensor and peak knee extensor moment in early stance (r=0.467, p=0.021) and in terminal stance (r=0.416, p=0.043). Conclusion There is no correlation between muscle strength and gross motor function. However, this study showed that muscle strength, especially of the extensor muscle group of the hip and knee joints, might play a critical role in gait by stabilizing pelvic motion and decreasing energy consumption in a flexed knee gait. PMID:26632404

Relationships between Isometric Muscle Strength, Gait Parameters, and Gross Motor Function Measure in Patients with Cerebral Palsy.

PubMed

Shin, Hyung Ik; Sung, Ki Hyuk; Chung, Chin Youb; Lee, Kyoung Min; Lee, Seung Yeol; Lee, In Hyeok; Park, Moon Seok

2016-01-01

This study investigated the correlation between isometric muscle strength, gross motor function, and gait parameters in patients with spastic cerebral palsy and to find which muscle groups play an important role for gait pattern in a flexed knee gait. Twenty-four ambulatory patients (mean age, 10.0 years) with spastic cerebral palsy who were scheduled for single event multilevel surgery, including distal hamstring lengthening, were included. Preoperatively, peak isometric muscle strength was measured for the hip flexor, hip extensor, knee flexor, and knee extensor muscle groups using a handheld dynamometer, and three-dimensional (3D) gait analysis and gross motor function measure (GMFM) scoring were also performed. Correlations between peak isometric strength and GMFM, gait kinematics, and gait kinetics were analyzed. Peak isometric muscle strength of all muscle groups was not related to the GMFM score and the gross motor function classification system level. Peak isometric strength of the hip extensor and knee extensor was significantly correlated with the mean pelvic tilt (r=-0.588, p=0.003 and r=-0.436, p=0.033) and maximum pelvic obliquity (r=-0.450, p=0.031 and r=-0.419, p=0.041). There were significant correlations between peak isometric strength of the knee extensor and peak knee extensor moment in early stance (r=0.467, p=0.021) and in terminal stance (r=0.416, p=0.043). There is no correlation between muscle strength and gross motor function. However, this study showed that muscle strength, especially of the extensor muscle group of the hip and knee joints, might play a critical role in gait by stabilizing pelvic motion and decreasing energy consumption in a flexed knee gait.

THE INFLUENCE OF SEX AND MATURATION ON LANDING BIOMECHANICS: IMPLICATIONS FOR ACL INJURY

PubMed Central

Sigward, S. M.; Pollard, C. D.; Powers, C. M.

2010-01-01

During landing and cutting, females exhibit greater frontal plane moments at the knee (internal knee adductor moments or external knee abduction moments) and favor use of the knee extensors over the hip extensors to attenuate impact forces when compared to males. However, it is not known when this biomechanical profile emerges. The purpose of this study was to compare landing biomechanics between sexes across maturation levels. One hundred and nineteen male and female soccer players (9–22 years) participated. Subjects were grouped based on maturational development. Lower extremity kinematics and kinetics were obtained during a drop-land task. Dependent variables included the average internal knee adductor moment and sagittal plane knee/hip moment and energy absorption ratios during the deceleration phase of landing. When averaged across maturation levels, females demonstrated greater internal knee adductor moments (0.06±0.03 vs. 0.01±0.02 Nm/kg*m; P<0.005), knee/hip extensor moment ratios (2.0±0.1 vs. 1.4±0.1 Nm/kg*m; P<0.001), and knee/hip energy absorption ratios (2.9±0.1 vs. 1.96±0.1 Nm/kg*m; P<0.001) compared to males. Higher knee adductor moments combined with disproportionate use of knee extensors relative to hip extensors observed in females reflects a biomechanical pattern that increases ACL loading. This biomechanical strategy already was established in pre-pubertal female athletes. PMID:21210853

Early reduction in toe flexor strength is associated with physical activity in elderly men.

PubMed

Suwa, Masataka; Imoto, Takayuki; Kida, Akira; Yokochi, Takashi

2016-05-01

[Purpose] To compare the toe flexor, hand grip and knee extensor strengths of young and elderly men, and to examine the association between toe flexor strength and physical activity or inactivity levels. [Subjects and Methods] Young (n=155, 18-23 years) and elderly (n=60, 65-88 years) men participated in this study. Toe flexor, hand grip, and knee extensor strength were measured. Physical activity (time spent standing/walking per day) and inactivity (time spent sitting per day) were assessed using a self-administered questionnaire. [Results] Toe flexor, hand grip, and knee extensor strength of the elderly men were significantly lower than those of the young men. Standing/walking and sitting times of the elderly men were lower than those of the young men. Toe flexor strength correlated with hand grip and knee extensor strength in both groups. In elderly men, toe flexor strength correlated with standing/walking time. In comparison to the young men's mean values, toe flexor strength was significantly lower than knee extensor and hand grip strength in the elderly group. [Conclusion] The results suggest that age-related reduction in toe flexor strength is greater than those of hand grip and knee extensor strengths. An early loss of toe flexor strength is likely associated with reduced physical activity in elderly men.

Differences in muscle strength after ACL reconstruction do not influence cardiorespiratory responses to isometabolic exercise

PubMed Central

Andrade, Marília S.; Lira, Claudio A. B.; Vancini, Rodrigo L.; Nakamoto, Fernanda P.; Cohen, Moisés; Silva, Antonio C.

2014-01-01

Objectives To investigate whether the muscle strength decrease that follows anterior cruciate ligament (ACL) reconstruction would lead to different cardiorespiratory adjustments during dynamic exercise. Method Eighteen active male subjects were submitted to isokinetic evaluation of knee flexor and extensor muscles four months after ACL surgery. Thigh circumference was also measured and an incremental unilateral cardiopulmonary exercise test was performed separately for both involved and uninvolved lower limbs in order to compare heart rate, oxygen consumption, minute ventilation, and ventilatory pattern (breath rate, tidal volume, inspiratory time, expiratory time, tidal volume/inspiratory time) at three different workloads (moderate, anaerobic threshold, and maximal). Results There was a significant difference between isokinetic extensor peak torque measured in the involved (116.5±29.1 Nm) and uninvolved (220.8±40.4 Nm) limbs, p=0.000. Isokinetic flexor peak torque was also lower in the involved limb than in the uninvolved limb (107.8±15.4 and 132.5±26.3 Nm, p=0.004, respectively). Lower values were also found in involved thigh circumference as compared with uninvolved limb (46.9±4.3 and 48.5±3.9 cm, p=0.005, respectively). No differences were found between the lower limbs in any of the variables of the incremental cardiopulmonary tests at all exercise intensities. Conclusions Our findings indicate that, four months after ACL surgery, there is a significant deficit in isokinetic strength in the involved limb, but these differences in muscle strength requirement do not produce differences in the cardiorespiratory adjustments to exercise. Based on the hypotheses from the literature which explain the differences in the physiological responses to exercise for different muscle masses, we can deduce that, after 4 months of a rehabilitation program after an ACL reconstruction, individuals probably do not present differences in muscle oxidative and peripheral perfusion capacities that could elicit higher levels of peripheral cardiorepiratory stimulus during exercise. PMID:24838811

Characterizing Knee Loading Asymmetry in Individuals Following Anterior Cruciate Ligament Reconstruction Using Inertial Sensors

PubMed Central

Sigward, Susan M.; Chan, Ming-Sheng M.; Lin, Paige E.

2016-01-01

Limitations in the ability to identify knee extensor loading deficits during gait in individuals following anterior cruciate ligament reconstruction (ACLr) may underlie their persistence. A recent study suggested that shank angular velocity, directly output from inertial sensors, differed during gait between individuals post-ACLr and controls. However, it is not clear if this kinematic variable relates to knee moments calculated using joint kinematics and ground reaction forces. Heel rocker mechanics during loading response of gait, characterized by rapid shank rotation, require knee extensor control. Measures of shank angular velocity may be reflective of knee moments. This study investigated the relationship between shank angular velocity and knee extensor moment during gait in individuals (n=19) 96.7±16.8 days post-ACLr. Gait was assessed concurrently using inertial sensors and a marker-based motion system with force platforms. Peak angular velocity and knee extensor moment were strongly correlated (r=0.75, p<0.001) and between limb ratios of angular velocity predicted between limb ratios of extensor moment (r2=0.57 ,p<0.001) in the absence of between limb differences in spatiotemporal gait parameters. The strength of these relationships indicate that shank kinematic data offer meaningful information regarding knee loading and provide a potential alternative to full motion analysis systems for identification of altered knee loading following ACLr PMID:27395452

Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.

PubMed

Gusi, N; Tomas-Carus, P; Häkkinen, A; Häkkinen, K; Ortega-Alonso, A

2006-02-15

To evaluate the short- and long-term efficacy of exercise therapy in a warm, waist-high pool in women with fibromyalgia. Thirty-four women (mean +/- SD tender points 17 +/- 1) were randomly assigned to either an exercise group (n = 17) to perform 3 weekly sessions of training including aerobic, proprioceptive, and strengthening exercises during 12 weeks, or to a control group (n = 17). Maximal unilateral isokinetic strength was measured in the knee extensors and flexors in concentric and eccentric actions at 60 degrees /second and 210 degrees /second, and in the shoulder abductors and adductors in concentric contractions. Health-related quality of life (HRQOL) was assessed using the EQ-5D questionnaire; pain was assessed on a visual analog scale. All were measured at baseline, posttreatment, and after 6 months. The strength of the knee extensors in concentric actions increased by 20% in both limbs after the training period, and these improvements were maintained after the de-training period in the exercise group. The strength of other muscle actions measured did not change. HRQOL improved by 93% (P = 0.007) and pain was reduced by 29% (P = 0.012) in the exercise group during the training, but pain returned close to the pretraining level during the subsequent de-training. However, there were no changes in the control group during the entire period. The therapy relieved pain and improved HRQOL and muscle strength in the lower limbs at low velocity in patients with initial low muscle strength and high number of tender points. Most of these improvements were maintained long term.

Creatine supplementation and physical training in patients with COPD: A double blind, placebo-controlled study

PubMed Central

Faager, Gun; Söderlund, Karin; Sköld, Carl Magnus; Rundgren, Siw; Tollbäck, Anna; Jakobsson, Per

2006-01-01

Study objectives Patients with chronic obstructive pulmonary disease (COPD) have low exercise capacity and low content of high energetic phosphates in their skeletal muscles. The aim of the present study was to investigate whether creatine supplementation together with exercise training may increase physical performance compared with exercise training in patients with COPD. Design In a randomized, double-blind, placebo-controlled study, 23 patients with COPD (forced expiratory volume in one second [FEV1] < 70% of predicted) were randomized to oral creatine (n = 13) or placebo (n = 10) supplementation during an 8-week rehabilitation programme including exercise training. Physical performance was assessed by Endurance Shuttle Walking Test (ESWT), dyspnea and leg fatigue with Borg CR-10, quality of life with St George’s Respiratory Questionnaire (SGRQ). In addition, lung function test, artery blood gases, grip strength test, muscle strength and fatigue in knee extensors were measured. Results COPD patients receiving creatine supplementation increased their average walking time by 61% (ESWT) (p < 0.05) after the training period compared with 48% (p = 0.07) in the placebo group. Rated dyspnea directly after the ESWT decreased significantly from 7 to 5 (p < 0.05) in the creatine group. However, the difference between the groups was not statistically significant neither in walking time nor in rated dyspnea. Creatine supplementation did not increase the health related quality of life, lung function, artery blood gases, grip strength and knee extensor strength/fatigue. Conclusions Oral creatine supplementation in combination with exercise training showed no significant improvement in physical performance, measured as ESWT, in patients with COPD compared with exercise training alone. PMID:18044100

Sex differences in neuromuscular function after repeated eccentric contractions of the knee extensor muscles.

PubMed

Lee, Andrea; Baxter, Jake; Eischer, Claire; Gage, Matt; Hunter, Sandra; Yoon, Tejin

2017-06-01

This study examined the mechanisms for force and power reduction during and up to 48 h after maximal eccentric contractions of the knee extensor muscles in young men and women. 13 men (22.8 ± 2.6 years) and 13 women (21.6 ± 2.2 years) performed 150 maximal effort eccentric contractions (5 sets of 30) with the knee extensor muscles at 60° s -1 . Maximal voluntary isometric contractions (MVIC) and maximal voluntary concentric contractions (MVCC) were performed before and after the 150 eccentric contractions. The MVCCs involved a set of two isokinetic contractions at 60° s -1 and sets of isotonic contractions performed at seven different resistance loads (1 N m, 10, 20, 30, 40, 50, and 60% MVIC). Electrical stimulation was used during the MVICs and at rest to determine changes in voluntary activation and contractile properties. At baseline, men were stronger than women (MVIC: 276 ± 48 vs. 133 ± 37 N m) and more powerful (MVCC: 649 ± 77 vs. 346 ± 78 W). At termination of the eccentric contractions, voluntary activation, resting twitch amplitude, and peak power during concentric contractions at the seven loads and at 60° s -1 decreased (P < 0.05) similarly in the men and women. At 48 h post-exercise, the MVIC torque, power (for loads ≥20-60% MVIC), and voluntary activation remained depressed (P < 0.05), but the resting twitch had returned to baseline (P > 0.05) with no sex differences. Central mechanisms were primarily responsible for the depressed maximal force production up to 48 h after repeated eccentric contractions of the knee extensors and these mechanisms were similar in men and women.

Cold application for neuromuscular recovery following intense lower-body exercise.

PubMed

Pointon, Monique; Duffield, Rob; Cannon, Jack; Marino, Frank E

2011-12-01

This study examined the effects of cold therapy (COLD) on recovery of voluntary and evoked contractile properties following high-intensity, muscle-damaging and fatiguing exercise. Ten resistance-trained males performed 6 × 25 maximal concentric/eccentric muscle contractions of the dominant knee extensors (KE) followed by a 20-min recovery (COLD v control) in a randomized cross-over design. Voluntary and evoked neuromuscular properties of the right KE, ratings of perceived muscle soreness (MS) and pain, and blood markers for muscle damage were measured pre- and post-exercise, and immediately post-recovery, 2, 24 and 48-h post-recovery. Exercise resulted in decrements in voluntary and evoked torque, increased MS and elevated muscle damage markers (p < 0.05). Measures of maximal voluntary contraction (MVC) or voluntary activation (VA) were not significantly enhanced by COLD (p > 0.05). Activation of right KE decreased post-exercise with increased activation of biceps femoris (BF) (p < 0.05). However, no significant differences were evident between conditions of activation of KE and hamstrings at any time point (p > 0.05). No significant differences were observed between conditions for creatine kinase or asparate aminotransferase (p > 0.05). However, perceptual ratings of pain were significantly (p < 0.05) lower following COLD compared to control. In conclusion, following damage to the contractile apparatus, COLD did not significantly hasten the recovery of peripheral contractile trauma. Despite no beneficial effect of COLD on recovery of MVC, perceptions of pain were reduced following COLD.

Lean muscle volume of the thigh has a stronger relationship with muscle power than muscle strength in women with knee osteoarthritis.

PubMed

Davison, Michael J; Maly, Monica R; Keir, Peter J; Hapuhennedige, Sandani M; Kron, Amie T; Adachi, Jonathan D; Beattie, Karen A

2017-01-01

Thigh lean muscle and intramuscular fat have been implicated in the impairment of physical function observed in people with knee osteoarthritis. We investigated the relationships of quadriceps and hamstrings intramuscular fat fraction and lean muscle volume with muscle power and strength, controlling for neuromuscular activation, and physical performance in women with knee OA. Women (n=20) 55years or older with symptomatic, radiographic knee osteoarthritis underwent a 3.0T magnetic resonance imaging scan of the thigh of their most symptomatic knee. Axial fat-separated images were analyzed using software to quantify intramuscular fat and lean muscle volumes of the quadriceps and hamstrings. To quantify strength and power of the knee extensors and flexors, participants performed maximum voluntary isometric contraction and isotonic knee extensions and flexions, respectively. Electromyography of the quadriceps and hamstrings was measured. Participants also completed five physical performance tests. Quadriceps and hamstrings lean muscle volumes were related to isotonic knee extensor (B=0.624; p=0.017) and flexor (B=1.518; p=0.032) power, but not knee extensor (B=0.001; p=0.615) or flexor (B=0.001; p=0.564) isometric strength. Intramuscular fat fractions were not related to isotonic knee extensor or flexor power, nor isometric strength. No relationships were found between intramuscular fat or lean muscle volume and physical performance. Muscle power may be more sensitive than strength to lean muscle mass in women with knee osteoarthritis. Thigh lean muscle mass, but neither intramuscular nor intermuscular fat, is related to knee extensor and flexor power in women with knee osteoarthritis. Copyright © 2016 Elsevier Ltd. All rights reserved.

The influence of sex and maturation on landing biomechanics: implications for anterior cruciate ligament injury.

PubMed

Sigward, S M; Pollard, C D; Powers, C M

2012-08-01

During landing and cutting, females exhibit greater frontal plane moments at the knee (internal knee adductor moments or external knee abduction moments) and favor the use of the knee extensors over the hip extensors to attenuate impact forces when compared with males. However, it is not known when this biomechanical profile emerges. The purpose of this study was to compare landing biomechanics between sexes across maturation levels. One hundred and nineteen male and female soccer players (9-22 years) participated. Subjects were grouped based on maturational development. Lower extremity kinematics and kinetics were obtained during a drop-land task. Dependent variables included the average internal knee adductor moment and sagittal plane knee/hip moment and energy absorption ratios during the deceleration phase of landing. When averaged across maturation levels, females demonstrated greater internal knee adductor moments (0.06±0.03 vs 0.01±0.02 N m/kg m; P<0.005), knee/hip extensor moment ratios (2.0±0.1 vs 1.4±0.1 N m/kg m; P<0.001) and knee/hip energy absorption ratios (2.9±0.1 vs 1.96±0.1 N m/kg m; P<0.001) compared with males. Higher knee adductor moments combined with disproportionate use of knee extensors relative to hip extensors observed in females reflect a biomechanical pattern that increases anterior cruciate ligament loading. This biomechanical strategy already was established in pre-pubertal female athletes. © 2011 John Wiley & Sons A/S.

Decrements in knee extensor and flexor strength are associated with performance fatigue during simulated basketball game-play in adolescent, male players.

PubMed

Scanlan, Aaron T; Fox, Jordan L; Borges, Nattai R; Delextrat, Anne; Spiteri, Tania; Dalbo, Vincent J; Stanton, Robert; Kean, Crystal O

2018-04-01

This study quantified lower-limb strength decrements and assessed the relationships between strength decrements and performance fatigue during simulated basketball. Ten adolescent, male basketball players completed a circuit-based, basketball simulation. Sprint and jump performance were assessed during each circuit, with knee flexion and extension peak concentric torques measured at baseline, half-time, and full-time. Decrement scores were calculated for all measures. Mean knee flexor strength decrement was significantly (P < 0.05) related to sprint fatigue in the first half (R = 0.65), with dominant knee flexor strength (R = 0.67) and dominant flexor:extensor strength ratio (R = 0.77) decrement significantly (P < 0.05) associated with sprint decrement across the entire game. Mean knee extensor strength (R = 0.71), dominant knee flexor strength (R = 0.80), non-dominant knee flexor strength (R = 0.75), mean knee flexor strength (R = 0.81), non-dominant flexor:extensor strength ratio (R = 0.71), and mean flexor:extensor strength ratio (R = 0.70) decrement measures significantly (P < 0.05) influenced jump fatigue during the entire game. Lower-limb strength decrements may exert an important influence on performance fatigue during basketball activity in adolescent, male players. Consequently, training plans should aim to mitigate lower-limb fatigue to optimise sprint and jump performance during game-play.

Leg blood flow is impaired during small muscle mass exercise in patients with COPD.

PubMed

Iepsen, U W; Munch, G W; Rugbjerg, M; Ryrsø, C K; Secher, N H; Hellsten, Y; Lange, P; Pedersen, B K; Thaning, P; Mortensen, S P

2017-09-01

Skeletal muscle blood flow is regulated to match the oxygen demand and dysregulation could contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). We measured leg hemodynamics and metabolites from vasoactive compounds in muscle interstitial fluid and plasma at rest, during one-legged knee-extensor exercise, and during arterial infusions of sodium nitroprusside (SNP) and acetylcholine (ACh), respectively. Ten patients with moderate to severe COPD and eight age- and sex-matched healthy controls were studied. During knee-extensor exercise (10 W), leg blood flow was lower in the patients compared with the controls (1.82 ± 0.11 vs. 2.36 ± 0.14 l/min, respectively; P < 0.05), which compromised leg oxygen delivery (372 ± 26 vs. 453 ± 32 ml O 2 /min, respectively; P < 0.05). At rest, plasma endothelin-1 (vasoconstrictor) was higher in the patients with COPD ( P < 0.05) and also tended to be higher during exercise ( P = 0.07), whereas the formation of interstitial prostacyclin (vasodilator) was only increased in the controls. There was no difference between groups in the nitrite/nitrate levels (vasodilator) in plasma or interstitial fluid during exercise. Moreover, patients and controls showed similar vasodilatory capacity in response to both endothelium-independent (SNP) and endothelium-dependent (ACh) stimulation. The results suggest that leg muscle blood flow is impaired during small muscle mass exercise in patients with COPD possibly due to impaired formation of prostacyclin and increased levels of endothelin-1. NEW & NOTEWORTHY This study demonstrates that chronic obstructive pulmonary disease (COPD) is associated with a reduced blood flow to skeletal muscle during small muscle mass exercise. In contrast to healthy individuals, interstitial prostacyclin levels did not increase during exercise and plasma endothelin-1 levels were higher in the patients with COPD. Copyright © 2017 the American Physiological Society.

Age Differences in Dynamic Fatigability and Variability of Arm and Leg Muscles: Associations with Physical Function

PubMed Central

Senefeld, Jonathon; Yoon, Tejin; Hunter, Sandra K.

2016-01-01

Introduction It is not known whether the age-related increase in fatigability of fast dynamic contractions in lower limb muscles also occurs in upper limb muscles. We compared age-related fatigability and variability of maximal-effort repeated dynamic contractions in the knee extensor and elbow flexor muscles; and determined associations between fatigability, variability of velocity between contractions and functional performance. Methods 35 young (16 males; 21.0±2.6 years) and 32 old (18 males; 71.3±6.2 years) adults performed a dynamic fatiguing task involving 90 maximal-effort, fast, concentric, isotonic contractions (1 contraction/3 s) with a load equivalent to 20% maximal voluntary isometric contraction (MVIC) torque with the elbow flexor and knee extensor muscles on separate days. Old adults also performed tests of balance and walking endurance. Results Old adults had greater fatigue-related reductions in peak velocity compared with young adults for both the elbow flexor and knee extensor muscles (P<0.05) with no sex differences (P>0.05). Old adults had greater variability of peak velocity during the knee extensor, but not during the elbow flexor fatiguing task. The age difference in fatigability was greater for the knee extensor muscles (35.9%) compared with elbow flexor muscles (9.7%, P<0.05). Less fatigability of the knee extensor muscles was associated with greater walking endurance (r=−0.34, P=0.048) and balance (r=−0.41, P=0.014) among old adults. Conclusions An age-related increase in fatigability of a dynamic fatiguing task was greater for the knee extensor compared with the elbow flexor muscles in males and females, and greater fatigability was associated with lesser walking endurance and balance. PMID:27989926

Early reduction in toe flexor strength is associated with physical activity in elderly men

PubMed Central

Suwa, Masataka; Imoto, Takayuki; Kida, Akira; Yokochi, Takashi

2016-01-01

[Purpose] To compare the toe flexor, hand grip and knee extensor strengths of young and elderly men, and to examine the association between toe flexor strength and physical activity or inactivity levels. [Subjects and Methods] Young (n=155, 18–23 years) and elderly (n=60, 65–88 years) men participated in this study. Toe flexor, hand grip, and knee extensor strength were measured. Physical activity (time spent standing/walking per day) and inactivity (time spent sitting per day) were assessed using a self-administered questionnaire. [Results] Toe flexor, hand grip, and knee extensor strength of the elderly men were significantly lower than those of the young men. Standing/walking and sitting times of the elderly men were lower than those of the young men. Toe flexor strength correlated with hand grip and knee extensor strength in both groups. In elderly men, toe flexor strength correlated with standing/walking time. In comparison to the young men’s mean values, toe flexor strength was significantly lower than knee extensor and hand grip strength in the elderly group. [Conclusion] The results suggest that age-related reduction in toe flexor strength is greater than those of hand grip and knee extensor strengths. An early loss of toe flexor strength is likely associated with reduced physical activity in elderly men. PMID:27313353

Rate of Torque Development and Feedforward Control of the Hip and Knee Extensors: Gender Differences.

PubMed

Stearns-Reider, Kristen M; Powers, Christopher M

2017-10-06

The purpose of this study was to determine whether women demonstrate decreased rate of torque development (RTD) of the hip and knee extensors and altered onset timing of the vastus lateralis and gluteus maximus during a drop-jump task when compared with men. On average, women demonstrated significantly lower normalized RTD of the hip extensors (women: 11.6 ± 1.3 MVT.s -1 , men: 13.1 ± 0.9 MVT.s -1 ; p ≤ .01); however, there was no significant difference in knee extensor RTD. Women also demonstrated significantly earlier activation of their vastus lateralis (women: 206.0 ± 130.6 ms, men: 80.9 ± 69.6 ms; p ≤ .01) and gluteus maximus (women: 85.7 ± 58.6 ms, men: 54.5 ± 35.4 ms; p = .02). In both men and women, there was a significant negative correlation between the hip extensor RTD and the vastus lateralis electromyographic onset time (men: r = -.386, p = .046; women: r = -.531, p = .008). The study findings suggest that women may utilize a feedforward control strategy in which they activate their knee extensors earlier than men to compensate for deficits in hip extensor RTD. The impaired capacity to rapidly stabilize the hip and knee joints during dynamic maneuvers may contribute to the increased risk of anterior cruciate ligament injury observed in women.

Exercise metabolism in human skeletal muscle exposed to prior eccentric exercise

PubMed Central

Asp, Sven; Daugaard, Jens R; Kristiansen, Søren; Kiens, Bente; Richter, Erik A

1998-01-01

The effects of unaccustomed eccentric exercise on exercise metabolism during a subsequent bout of graded concentric exercise were investigated in seven healthy male subjects. Arterial and bilateral femoral venous catheters were inserted 2 days after eccentric exercise of one thigh (eccentric thigh) and blood samples were taken before and during graded two-legged concentric knee-extensor exercise. Muscle biopsies were obtained from the eccentric and control vastus lateralis before (rest) and after (post) the concentric exercise bout. Maximal knee-extensor concentric exercise capacity was decreased by an average of 23 % (P < 0.05) in the eccentric compared with the control thigh. The resting muscle glycogen content was lower in the eccentric thigh than in the control thigh (402 ± 30 mmol (kg dry wt)−1vs. 515 ± 26 mmol (kg dry wt)−1, means ± s.e.m., P < 0.05), and following the two-legged concentric exercise this difference substantially increased (190 ± 46 mmol (kg dry wt)−1vs. 379 ± 58 mmol (kg dry wt)−1, P < 0.05) despite identical power and duration of exercise with the two thighs. There was no measurable difference in glucose uptake between the eccentric and control thigh before or during the graded two-legged concentric exercise. Lactate release was higher from the eccentric thigh at rest and, just before termination of the exercise bout, release of lactate decreased from this thigh (suggesting decreased glycogenolysis), whereas no decrease was found from the contralateral control thigh. Lower glycerol release from the eccentric thigh during the first, lighter part of the exercise (P < 0.05) suggested impaired triacylglycerol breakdown. At rest, sarcolemmal GLUT4 glucose transporter content and glucose transport were similar in the two thighs, and concentric exercise increased sarcolemmal GLUT4 content and glucose transport capacity similarly in the two thighs. It is concluded that in muscle exposed to prior eccentric contractions, exercise at a given power output requires a higher relative workload than in undamaged muscle. This increases utilization of the decreased muscle glycogen stores, contributing to decreased endurance. PMID:9547403

Knee stabilisation following infected knee arthroplasty with bone loss and extensor mechanism impairment using a modular cemented nail.

PubMed

Rao, M C; Richards, O; Meyer, C; Jones, R Spencer

2009-12-01

Infected Total Knee Replacement with significant bone loss and loss of extensor mechanism poses a difficult management problem. Arthrodesis relying on bony union can be difficult to achieve and can result in significant limb shortening. We retrospectively looked at the outcome of seven patients with significant bone loss and extensor mechanism insufficiency following infected TKR who underwent knee stabilisation using a modular cemented nail. The nail relied on the strong coupling mechanism between the modular femoral and tibial components. Pain score improved from a mean of 7.9 pre-operatively to 1.5 post-operatively at a mean follow up of 39.6 months (range 7-68) months. Two patients underwent technically easy revision nailing for recurrent infection and aseptic loosening. The Endo-Model(R) Knee Fusion Nail (Newsplint, UK/Waldemar Link, GmbH & Co. KG, Hamburg, Germany) has good early results in terms of pain relief and provides a stable knee in cases with significant bone loss and extensor mechanism insufficiency following an infected TKR thus avoiding an above knee amputation.

Effects of strength training program on hip extensors and knee extensors strength of lower limb in children with spastic diplegic cerebral palsy.

PubMed

Aye, Thanda; Thein, Soe; Hlaing, Thaingi

2016-01-01

[Purpose] The purpose of this study was to determine whether strength training programs for hip extensors and knee extensors improve gross motor function of children with cerebral palsy in Myanmar. [Subjects and Methods] Forty children (25 boys and 15 girls, mean age: 6.07 ± 2.74 years) from National Rehabilitation Hospital, Yangon, Myanmar, who had been diagnosed with spastic diplegic cerebral palsy, Gross Motor Classification System I and II participated in a 6-week strength training program (45 minutes per day, 3 days per week) on hip and knee extensors. Assessment was made, before and after intervention, of the amount of training weight in pounds, as well as Gross Motor Function Measure (GMFM) dimensions D (standing) and E (walking, running, jumping). [Results] All scores had increased significantly after the strength-training program. [Conclusion] A simple method of strength-training program for hip and knee extensors might lead to improved muscle strength and gross motor function in children with spastic diplegic cerebral palsy.

Effects of strength training program on hip extensors and knee extensors strength of lower limb in children with spastic diplegic cerebral palsy

PubMed Central

Aye, Thanda; Thein, Soe; Hlaing, Thaingi

2016-01-01

[Purpose] The purpose of this study was to determine whether strength training programs for hip extensors and knee extensors improve gross motor function of children with cerebral palsy in Myanmar. [Subjects and Methods] Forty children (25 boys and 15 girls, mean age: 6.07 ± 2.74 years) from National Rehabilitation Hospital, Yangon, Myanmar, who had been diagnosed with spastic diplegic cerebral palsy, Gross Motor Classification System I and II participated in a 6-week strength training program (45 minutes per day, 3 days per week) on hip and knee extensors. Assessment was made, before and after intervention, of the amount of training weight in pounds, as well as Gross Motor Function Measure (GMFM) dimensions D (standing) and E (walking, running, jumping). [Results] All scores had increased significantly after the strength-training program. [Conclusion] A simple method of strength-training program for hip and knee extensors might lead to improved muscle strength and gross motor function in children with spastic diplegic cerebral palsy. PMID:27065561

Rhythmic Isometric Fatigue Patterns of the Elbow Flexors and Knee Extensors

ERIC Educational Resources Information Center

Ordway, George A.; And Others

1977-01-01

During a rhythmic, all-out task, the rates of fatigue experienced by elbow flexor and knee extendor muscle groups tend to differ, with the elbow flexors fatiguing more rapidly initially, but reaching a plateau at a relatively higher level than the knee extensors. (Author)

Changes in diffusion tensor imaging (DTI) eigenvalues of skeletal muscle due to hybrid exercise training.

PubMed

Okamoto, Yoshikazu; Kemp, Graham J; Isobe, Tomonori; Sato, Eisuke; Hirano, Yuji; Shoda, Junichi; Minami, Manabu

2014-12-01

Several studies have proposed the cell membrane as the main water diffusion restricting factor in the skeletal muscle cell. We sought to establish whether a particular form of exercise training (which is likely to affect only intracellular components) could affect water diffusion. The purpose of this study is to characterise prospectively the changes in diffusion tensor imaging (DTI) eigenvalues of thigh muscle resulting from hybrid training (HYBT) in patients with non-alcoholic fatty liver disease (NAFLD). Twenty-one NAFLD patients underwent HYBT for 30 minutes per day, twice a week for 6 months. Patients were scanned using DTI of the thigh pre- and post-HYBT. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), the three eigenvalues lambda 1 (λ1), λ2, λ3, and the maximal cross sectional area (CSA) were measured in bilateral thigh muscles: knee flexors (biceps femoris (BF), semitendinosus (ST), semimembranous (SM)) and knee extensors (medial vastus (MV), intermediate vastus (IV), lateral vastus (LV), and rectus femoris (RF)), and compared pre- and post-HYBT by paired t-test. Muscle strength of extensors (P<0.01), but not flexors, increased significantly post-HYBT. For FA, ADC and eigenvalues, the overall picture was of increase. Some (P<0.05 in λ2 and P<0.01 in λ1) eigenvalues of flexors and all (λ1-λ3) eigenvalues of extensors increased significantly (P<0.01) post-HYBT. HYBT increased all 3 eigenvalues. We suggest this might be caused by enlargement of muscle intracellular space. Copyright © 2014 Elsevier Inc. All rights reserved.

Extensor Mechanism Disruption after Total Knee Arthroplasty: A Case Series and Review of Literature.

PubMed

Vaishya, Raju; Agarwal, Amit Kumar; Vijay, Vipul

2016-02-04

Extensor mechanism disruption following total knee arthroplasty (TKA) is a rare but devastating complication. These patients may require revision of the implants, but even then, it may not be possible to restore the normal function of the knee after the disruption. The patterns of extensor mechanism disruption can broadly be classified into three types: suprapatellar (quadriceps tendon rupture), transpatellar (patellar fracture), or infrapatellar (patellar tendon rupture). Infrapatellar tendon ruptures are the worst injuries, as they carry maximum morbidity and are challenging to manage. The disruption of the extensor mechanism may occur either intra-operatively or in the immediate postoperative period due to an injury. The treatment of extensor mechanism complications after TKA may include either nonsurgical management or surgical intervention in the form of primary repair or reconstruction with autogenous, allogeneic, or synthetic substitutes. We have provided an algorithm for the management of extensor mechanism disruption after TKA.

Impact of resistance exercise program on functional capacity and muscular strength of knee extensor in pre-frail community-dwelling older women: a randomized crossover trial.

PubMed

Lustosa, Lygia P; Silva, Juscélio P; Coelho, Fernanda M; Pereira, Daniele S; Parentoni, Adriana N; Pereira, Leani S M

2011-01-01

Frailty syndrome in elderly people is characterized by a reduction of energy reserves and also by a decreased of resistance to stressors, resulting in an increase of vulnerability. The aim of this study was to verify the effect of a muscle-strengthening program with load in pre-frail elder women with regards to the functional capacity, knee extensor muscle strength and their correlation. Thrity-two pre-frail community-dwelling women participated in this study. Potential participants with cognitive impairment (MEEM), lower extremities orthopedic surgery, fractures, inability to walk unaided, neurological diseases, acute inflammatory disease, tumor growth, regular physical activity and current use of immunomodulators were excluded. All partcipants were evaluated by a blinded assessor using: Timed up and go (TUG), 10-Meter Walk Test (10MWT) and knee extensor muscle strength (Byodex System 3 Pro® isokinetic dynamometer at angular speeds of 60 and 180(0)/s). The intervention consisted of strengthening exercises of the lower extremities at 70% of 1RM, three times/ week for ten weeks. The statistical analysis was performed using the ANOVA and Spearman tests After the intervention, it was observed statistical significance on the work at 180(0)/s (F=12.71, p=0.02), on the power at 180(0)/s (F=15.40, p=0.02) and on the functional capacity (TUG, F=9.54, p=0.01; TC10, F=3.80, p=0.01). There was a good negative and statistically significant correlation between the TUG and work at 60(0)/s, such as the TUG and work at 180(0)/s (r=-0.65, p=0.01; r=-0.72, p=0.01). The intervention improved the muscular power and the functional capacity. The increase of the power correlated with function, which is an important variable of the quality of life in the pre-frail elders. Article registered in the ISRCT register under number ISRCTN62824599.

Effect of a physiotherapy rehabilitation program on knee osteoarthritis in patients with different pain intensities.

PubMed

Abdel-Aziem, Amr Almaz; Soliman, Elsadat Saad; Mosaad, Dalia Mohammed; Draz, Amira Hussin

2018-02-01

[Purpose] To examine the effect of physiotherapy rehabilitation program on moderate knee osteoarthritis in patients with different pain intensities. [Subjects and Methods] Sixty subjects (37 men and 23 women) with moderate knee osteoarthritis participated in the current study. Randomization software was used to select the participating subjects' numbers from the clinic records. They were classified into three groups according to pain intensity: mild, moderate, and severe pain groups. All groups underwent a standard set of pulsed electromagnetic field, ultrasound, stretching exercises, and strengthening exercises. Pain intensity, knee range of motion, knee function, and isometric quadriceps strength were evaluated using the visual analogue scale, universal goniometer, Western Ontario and McMaster Universities osteoarthritis index, and Jamar hydraulic dynamometer, respectively. The evaluation was performed before and after a 4-week rehabilitation program. [Results] All groups showed significant differences in pain intensity, knee range of motion, isometric quadriceps strength, and knee function. The score change in moderate pain group was significantly greater than those in mild and severe pain groups. [Conclusion] Pain intensity is one of the prominent factors that are responsible for the improvement of knee osteoarthritis. Consequently, pain intensity should be considered during rehabilitation of knee osteoarthritis.

Fatigue and muscle-tendon stiffness after stretch-shortening cycle and isometric exercise.

PubMed

Toumi, Hechmi; Poumarat, Georges; Best, Thomas M; Martin, Alain; Fairclough, John; Benjamin, Mike

2006-10-01

The purpose of the present study was to compare vertical jump performance after 2 different fatigue protocols. In the first protocol, subjects performed consecutive sets of 10 repetitions of stretch-shortening cycle (SSC) contractions. In the second protocol, successive sets of 10 repetitions of isometric contractions were performed for 10 s with the knee at 90 degrees of flexion. The exercises were stopped when the subjects failed to reach 50% of their maximum voluntary isometric contractions. Maximal isometric force and maximal concentric power were assessed by performing supine leg presses, squat jumps, and drop jumps. Surface EMG was used to determine changes in muscle activation before and after fatigue. In both groups, the fatigue exercises reduced voluntary isometric force, maximal concentric power, and drop jump performance. Kinematic data showed a decrease in knee muscle-tendon stiffness accompanied by a lengthened ground contact time. EMG analysis showed that the squat and drop jumps were performed similarly before and after the fatigue exercise for both groups. Although it was expected that the stiffness would decrease more after SSC than after isometric fatigue (as a result of a greater alteration of the reflex sensitivity SSC), our results showed that both protocols had a similar effect on knee muscle stiffness during jumping exercises. Both fatigue protocols induced muscle fatigue, and the decrease in jump performance was linked to a decrease in the strength and stiffness of the knee extensor muscles.

Whole-Body Vibration and the Prevention and Treatment of Delayed-Onset Muscle Soreness

PubMed Central

Aminian-Far, Atefeh; Hadian, Mohammad-Reza; Olyaei, Gholamreza; Talebian, Saeed; Bakhtiary, Amir Hoshang

2011-01-01

Abstract Context: Numerous recovery strategies have been used in an attempt to minimize the symptoms of delayed-onset muscle soreness (DOMS). Whole-body vibration (WBV) has been suggested as a viable warm-up for athletes. However, scientific evidence to support the protective effects of WBV training (WBVT) on muscle damage is lacking. Objective: To investigate the acute effect of WBVT applied before eccentric exercise in the prevention of DOMS. Design: Randomized controlled trial. Setting: University laboratory. Patients or Other Participants: A total of 32 healthy, untrained volunteers were randomly assigned to either the WBVT (n  =  15) or control (n  =  17) group. Intervention(s): Volunteers performed 6 sets of 10 maximal isokinetic (60°/s) eccentric contractions of the dominant-limb knee extensors on a dynamometer. In the WBVT group, the training was applied using a vibratory platform (35 Hz, 5 mm peak to peak) with 100° of knee flexion for 60 seconds before eccentric exercise. No vibration was applied in the control group. Main Outcome Measure(s): Muscle soreness, thigh circumference, and pressure pain threshold were recorded at baseline and at 1, 2, 3, 4, 7, and 14 days postexercise. Maximal voluntary isometric and isokinetic knee extensor strength were assessed at baseline, immediately after exercise, and at 1, 2, 7, and 14 days postexercise. Serum creatine kinase was measured at baseline and at 1, 2, and 7 days postexercise. Results: The WBVT group showed a reduction in DOMS symptoms in the form of less maximal isometric and isokinetic voluntary strength loss, lower creatine kinase levels, and less pressure pain threshold and muscle soreness (P < .05) compared with the control group. However, no effect on thigh circumference was evident (P < .05). Conclusions: Administered before eccentric exercise, WBVT may reduce DOMS via muscle function improvement. Further investigation should be undertaken to ascertain the effectiveness of WBVT in attenuating DOMS in athletes. PMID:21214349

Lower extremity muscle functions during full squats.

PubMed

Robertson, D G E; Wilson, Jean-Marie J; St Pierre, Taunya A

2008-11-01

The purpose of this research was to determine the functions of the gluteus maximus, biceps femoris, semitendinosus, rectus femoris, vastus lateralis, soleus, gastrocnemius, and tibialis anterior muscles about their associated joints during full (deep-knee) squats. Muscle function was determined from joint kinematics, inverse dynamics, electromyography, and muscle length changes. The subjects were six experienced, male weight lifters. Analyses revealed that the prime movers during ascent were the monoarticular gluteus maximus and vasti muscles (as exemplified by vastus lateralis) and to a lesser extent the soleus muscles. The biarticular muscles functioned mainly as stabilizers of the ankle, knee, and hip joints by working eccentrically to control descent or transferring energy among the segments during scent. During the ascent phase, the hip extensor moments of force produced the largest powers followed by the ankle plantar flexors and then the knee extensors. The hip and knee extensors provided the initial bursts of power during ascent with the ankle extensors and especially a second burst from the hip extensors adding power during the latter half of the ascent.

Gait adaptations in patients with chronic posterior instability of the knee.

PubMed

Hooper, D M; Morrissey, M C; Crookenden, R; Ireland, J; Beacon, J P

2002-03-01

A retrospective analysis was performed to assess gait in individuals with a long history of posterior knee instability. Descriptive study. There are few studies in the literature concerning evaluation of the biomechanics of the knee in patients with knee posterior instability. Nine individuals with posterior knee instability and a matched control group of uninjured subjects were tested in regards to knee kinematics and kinetics while walking and ascending and descending stairs. The mean follow up time for the individuals with posterior instability was 11.1 years. Individual satisfaction with the knee was measured by having participants complete the Flandry (also known as Hughston Clinic) self-assessment questionnaire. It was found that patients with knee posterior instability who indicated a higher level of satisfaction on the Flandry score walked in a manner that demonstrated greater peak knee extensor torque during stance phase, while less satisfied patients with knee posterior instability demonstrated lower peak knee extensor torque. There was a significant correlation between the self-assessment score and the peak knee extensor torque during level walking (P=0.003). During stair ascent and descent, patients with posterior instability averaged lower knee extensor torque and power than the control subjects, but those differences were only statistically significant in power while descending stairs (P=0.048). Individuals with chronic knee posterior instability modify their gait, and the adaptation can be predicted based upon the individuals self-assessment of their knee using the Flandry questionnaire. These data suggest that gait retraining may be a valuable addition to the traditional muscle strengthening programs, which are commonly used during conservative management of knee posterior instability.

Assessment of isokinetic knee strength in elite young female basketball players: correlation with vertical jump.

PubMed

Rouis, M; Coudrat, L; Jaafar, H; Filliard, J-R; Vandewalle, H; Barthelemy, Y; Driss, T

2015-12-01

To explore the isokinetic concentric strength of the knee muscle groups, and the relationship between the isokinetic knee extensors strength and the vertical jump performance in young elite female basketball players. Eighteen elite female basketball players performed a countermovement jump, and an isokinetic knee test using a Biodex dynamometer. The maximal isokinetic peak torque of the knee extensor and flexor muscles was recorded at four angular velocities (90°/s, 180°/s, 240°/s and 300°/s) for the dominant and non-dominant legs. The conventional hamstring/quadriceps ratio (H/Q) was assessed at each angular velocity for both legs. There was no significant difference between dominant and non-dominant leg whatever the angular velocity (all P>0.05). However, the H/Q ratio enhanced as the velocity increased from 180°/s to 300°/s (P<0.05). Furthermore, low to high significant positive correlations were detected between the isokinetic measures of the knee extensors and the vertical jump height. The highest one was found for the knee extensors peak torque at a velocity of 240°/s (r=0.88, P<0.001). The results accounted for an optimal velocity at which a strong relationship could be obtained between isokinetic knee extensors strength and vertical jump height. Interestingly, the H/Q ratio of the young elite female basketball players in the present study was unusual as it was close to that generally observed in regular sportsmen.

Vibration Platform Training in Women at Risk for Symptomatic Knee Osteoarthritis

PubMed Central

Segal, Neil A.; Glass, Natalie A.; Shakoor, Najia; Wallace, Robert

2013-01-01

Objective To determine whether a platform exercise program with vibration is more effective than the platform exercise alone for improving lower limb muscle strength and power in women age 45-60 with risk factors for knee osteoarthritis (OA). Design Randomized, controlled study Setting Academic center Participants 48 women age 45-60 years old with risk factors for knee OA (history of knee injury or surgery or BMI≥25kg/m2). Interventions Subjects were randomized to a twice weekly lower limb exercise program (quarter squat, posterolateral leg lifts, calf raises) on either a vertically vibrating (35Hz, 2mm), or a non-vibrating platform. Main Outcome Measurements The main outcome measures included change in isokinetic quadriceps strength, leg press power, and stair climb power by 12 weeks. Results 39 out of 48 enrolled participants completed the study (26 vibration and 13 control exercise). Nine participants discontinued the study after randomization mainly due to lack of time. There were no intergroup differences in age, BMI, or activity level. Isokinetic knee extensor strength did not significantly improve in either group. Leg press power improved by 92.0±69.7 W in the vibration group (p<.0001) and 58.2±96.2 W in the control group (p=0.0499), but did not differ between groups (p=0.2262). Stair climb power improved by 53.4±64.7 W in the vibration group (p=0.0004) and 55.7±83.3 W in the control group (p=0.0329), but did not differ between groups (p=0.9272). Conclusions Whole body vibration platforms have been marketed for increasing strength and power. In this group of asymptomatic middle-aged women with risk factors for knee OA, addition of vibration to a 12-week exercise program did not result in significantly greater improvement in lower limb strength or power than participation in the exercise program without vibration. PMID:22981005

Vibration platform training in women at risk for symptomatic knee osteoarthritis.

PubMed

Segal, Neil A; Glass, Natalie A; Shakoor, Najia; Wallace, Robert

2013-03-01

To determine whether a platform exercise program with vibration is more effective than platform exercise alone for improving lower limb muscle strength and power in women ages 45 to 60 with risk factors for knee osteoarthritis (OA). Randomized, controlled study. Academic center. A total of 48 women ages 45-60 years with risk factors for knee OA (a history of knee injury or surgery or body mass index ≥25 kg/m(2)). Subjects were randomly assigned to a twice-weekly lower limb exercise program (quarter squat, posterolateral leg lifts, calf raises, step-ups, and lunges) on either a vertically vibrating platform (35 Hz, 2 mm) or a nonvibrating platform. Change in isokinetic quadriceps strength, leg press power, and stair climb power by 12 weeks. A total of 39 of 48 enrolled participants completed the study (26 vibration and 13 control exercise). Nine participants discontinued the study after randomization mainly because of a lack of time. No intergroup differences in age, body mass index, or activity level existed. Isokinetic knee extensor strength did not significantly improve in either group. Leg press power improved by 92.0 ± 69.7 W in the vibration group (P < .0001) and 58.2 ± 96.2 W in the control group (P = .0499) but did not differ between groups (P = .2262). Stair climb power improved by 53.4 ± 64.7 W in the vibration group (P = .0004) and 55.7 ± 83.3 W in the control group (P = .0329) but did not differ between groups (P = .9272). Whole body vibration platforms have been marketed for increasing strength and power. In this group of asymptomatic middle-aged women with risk factors for knee OA, the addition of vibration to a 12-week exercise program did not result in significantly greater improvement in lower limb strength or power than did participation in the exercise program without vibration. Copyright © 2013 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Heterogeneity of physical function responses to exercise training in older adults.

PubMed

Chmelo, Elizabeth A; Crotts, Charlotte I; Newman, Jill C; Brinkley, Tina E; Lyles, Mary F; Leng, Xiaoyan; Marsh, Anthony P; Nicklas, Barbara J

2015-03-01

To describe the interindividual variability in physical function responses to supervised resistance and aerobic exercise training interventions in older adults. Data analysis of two randomized, controlled exercise trials. Community-based research centers. Overweight and obese (body mass index (BMI)≥27.0 kg/m2) sedentary men and women aged 65 to 79 (N=95). Five months of 4 d/wk of aerobic training (AT, n=40) or 3 d/wk of resistance training (RT, n=55). Physical function assessments: global measure of lower extremity function (Short Physical Performance Battery (SPPB)), 400-m walk, peak aerobic capacity (VO2 peak), and knee extensor strength. On average, both exercise interventions significantly improved physical function. For AT, there was a 7.9% increase in VO2 peak; individual absolute increases varied from 0.4 to 4.3 mL/kg per minute, and four participants (13%) showed no change or a decrease in VO2 peak. For RT, knee extensor strength improved an average of 8.1%; individual increases varied from 1.2 to 63.7 Nm, and 16 participants (30%) showed no change or a decrease in strength. Usual gait speed, 400-m walk time, chair rise time, and SPPB improved for the majority of AT participants and usual gait speed, chair rise time, and SPPB improved for the majority of RT participants, but there was wide variation in the magnitude of improvement. Only change in 400-m walk time with RT was related to exercise adherence (correlation coefficient=-0.31, P=.004). Despite sufficient levels of adherence to both exercise interventions, some participants did not improve function, and the magnitude of improvement varied widely. Additional research is needed to identify factors that optimize responsiveness to exercise to maximize its functional benefits in older adults. © 2015, Copyright the Authors Journal compilation © 2015, The American Geriatrics Society.

Does frontal knee kinematics predict treatment outcomes? Exploratory analyses from the Intensive Diet and Exercise for Arthritis (IDEA) trial.

PubMed

Hall, Michelle; Bennell, Kim L; Beavers, Daniel P; Wrigley, Tim V; DeVita, Paul; Messier, Stephen P

2018-04-27

Pain is a cardinal symptom of knee osteoarthritis (OA) and although conservative treatments such as exercise and diet related interventions can reduce pain, effects are modest and can be improved. Frontal plane knee joint motion has been associated with knee pain, and is suggested as a patient-specific characteristic on which to tailor interventions. Does the association between baseline frontal plane knee joint kinematics and pain-relief differ among overweight and obese people with knee OA who underwent an intervention from the Intensive Diet and Exercise for Arthritis (IDEA) clinical trial: diet-only, exercise-only, and combined diet and exercise intervention? 323 participants with knee OA were included in the analysis (77% females; 66 ± 6 years; 33.5 ± 3.7 kg/m 2 ). At baseline, frontal plane knee joint kinematics during walking were measured using 3-dimensional gait analysis and characterised as peak varus-valgus knee angle, peak varus-valgus excursion, and peak varus angular velocity. Pain was assessed at baseline and 18-month follow-up using the Western Ontario and McMaster Universities Osteoarthritis Index pain subscale. Linear regressions were performed unadjusted and adjusted for covariates to determine if the associations between baseline frontal plane knee joint kinematics and 18-month change in pain differed according to intervention. The interaction terms between the intervention and measures of frontal plane knee joint kinematics were not statistically significant (all P ≥ 0.05). We found no evidence to suggest that 18-months of either exercise, diet, or a combination of diet and exercise could be more effective than the other to improve pain based on frontal plane measures of knee kinematics. Copyright © 2018. Published by Elsevier B.V.

Elastic Bands in Combination With Free Weights in Strength Training: Neuromuscular Effects.

PubMed

Andersen, Vidar; Fimland, Marius S; Kolnes, Maria K; Saeterbakken, Atle H

2015-10-01

This study compared the effects of a variable vs. a constant lower limb resistance training program on muscle strength, muscle activation, and ballistic muscle performance at different knee angles. Thirty-two females were randomized to a constant resistance training free-weight group (FWG) or a variable resistance training group using free weights in combination with elastic bands (EBG). Two variations of the squat exercise (back squat and split) were performed 2 days per week for 10 weeks. Knee extensor maximal voluntary isometric contraction (MVC) and countermovement jump were assessed at knee angles of 60, 90, and 120° before and after the intervention. During the MVCs, muscle activation of the superficial knee extensor muscles was measured using surface electromyography. The FWG increased their MVCs at 60 and 90° (24 and 15%, respectively), whereas the EBG only increased significantly at 60° (15%). The FWG increased their jump height significantly at all angles (12-16%), whereas the EBG only improved significantly at 60 and 90° (15 and 10%, respectively). Both groups improved their 6-repetition maximum free-weight squat performance (EBG: 25% and FWG: 23%). There were no significant changes in muscle activation. In conclusion, constant and variable resistance training provided similar increases in dynamic and isometric strength, and ballistic muscle performance, albeit most consistently for the group training only with free weights.

The effect of knee extensor open kinetic chain resistance training in the ACL-injured knee.

PubMed

Barcellona, Massimo G; Morrissey, Matthew C; Milligan, Peter; Clinton, Melissa; Amis, Andrew A

2015-11-01

To investigate the effect of different loads of knee extensor open kinetic chain resistance training on anterior knee laxity and function in the ACL-injured (ACLI) knee. Fifty-eight ACLI subjects were randomised to one of three (12-week duration) training groups. The STAND group trained according to a standardised rehabilitation protocol. Subjects in the LOW and HIGH group trained as did the STAND group but with the addition of seated knee extensor open kinetic chain resistance training at loads of 2 sets of 20 repetition maximum (RM) and 20 sets of 2RM, respectively. Anterior knee laxity and measurements of physical and subjective function were performed at baseline, 6 and 12 weeks. Thirty-six subjects were tested at both baseline and 12 weeks (STAND n = 13, LOW n = 11, HIGH n = 12). The LOW group demonstrated a reduction in 133 N anterior knee laxity between baseline and 12 weeks testing when compared to the HIGH and the STAND groups (p = 0.009). Specifically, the trained-untrained knee laxity decreased an average of approximately 5 mm in the LOW group while remaining the same in the other two groups. Twelve weeks of knee extensor open kinetic chain resistance training at loads of 2 sets of 20RM led to a reduction in anterior knee laxity in the ACLI knee. This reduction in laxity does not appear to offer any significant short-term functional advantages when compared to a standard rehabilitation protocol. These results indicate that knee laxity can be decreased with resistance training of the thigh muscles. Randomised controlled trial, Level II.

Efficacy of isokinetic exercise on functional capacity and pain in patellofemoral pain syndrome.

PubMed

Alaca, Ridvan; Yilmaz, Bilge; Goktepe, A Salim; Mohur, Haydar; Kalyon, Tunc Alp

2002-11-01

To assess the effect of an isokinetic exercise program on symptoms and functions of patients with patellofemoral pain syndrome. A total of 22 consecutive patients with the complaint of anterior knee pain who met the inclusion criteria were recruited to assess the efficacy of isokinetic exercise on functional capacity, isokinetic parameters, and pain scores in patients with patellofemoral pain syndrome. A total of 37 knees were examined. Six-meter hopping, three-step hopping, and single-limb hopping course tests were performed for each patient with the measurements of the Lysholm scale and visual analog scale. Tested parameters were peak torque, total work, average power, and endurance ratios. Statistical analyses revealed that at the end of the 6-wk treatment period, functional and isokinetic parameters improved significantly, as did pain scores. There was not statistically significant correlation between different groups of parameters. The isokinetic exercise treatment program used in this study prevented the extensor power loss due to patellofemoral pain syndrome, but the improvement in the functional capacity was not correlated with the gained power.

Comparative effects of proprioceptive and isometric exercises on pain intensity and difficulty in patients with knee osteoarthritis: A randomised control study.

PubMed

Ojoawo, Adesola O; Olaogun, Matthew O B; Hassan, Mariam A

2016-11-14

The study compared the effects of isometric quadriceps exercise and proprioceptive exercise on pain, joint stiffness and physical difficulties of patients with knee osteoarthritis. Forty-five patients with history of knee osteoarthritis were randomly allocated into two groups; A with 23 subjects and B with 22 subjects. All subjects received infrared radiation for 20 minutes and kneading massage with methyl salicylate ointment. Group A underwent proprioceptive exercises while Group B had isometric quadriceps exercise. Each exercise session lasted for 10 minutes according to standard protocol, twice in a week for six weeks. Pre-treatment, 3rd week and 6th week pain intensity, joint stiffness and physical difficulties were assessed using Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. Statistical package for social sciences (SPSS) version 17 was used to analyse the data while descriptive and inferential statistics were used to summarise the result. Proprioceptive exercises reduced pain intensity significantly (F = 4.76; p = 0.00) at 6th week with effect size of 2.79, and physical difficulty (F = 3.69; p < 0.04) with effect size of 7.53 better than isometric exercises. There was a significant reduction in the pain intensity (F = 12.08; p < 0.001), and physical difficulties (F = 3.69, p = 0.04) in pre-treatment, 3rd week and 6th week in both Group A and B. Both exercises are effective but proprioceptive exercises may be more effective in the management of patients with knee osteoarthritis (KOA) than isometric exercises.

Do patients with knee osteoarthritis perform sit-to-stand motion efficiently?

PubMed

Anan, Masaya; Shinkoda, Koichi; Suzuki, Kentaro; Yagi, Masahide; Ibara, Takuya; Kito, Nobuhiro

2015-02-01

The sit-to-stand motion (STS) is a frequently executed activity that is affected by weakness in the quadriceps femoris muscle and knee joint pain in patients with knee osteoarthritis (OA). We investigated whether patients with knee OA can efficiently perform STS through mechanical energy transfer assessments. Participants were 20 women with knee OA and 17 age-matched asymptomatic controls. The center of mass (COM), segment angles, joint moments, and powers during STS were measured. The negative mechanical work in the proximal portion of the shank, negative mean powers in the distal portion of the pelvis and proximal portion of the shank, and the positive mean power in the proximal and distal portions of the thigh were significantly lower in the knee OA group than in the control group. Patients with knee OA primarily performed thoracic forward lean movement, shifting their COM closer to the base of support provided by the feet alone, in an attempt to achieve stability at and after buttocks-off. However, control ability, which generates and absorbs kinetic energy quickly, was not enhanced in these patients, and their motion was unable to increase absorption of the mechanical energy in hip extensors and reduce the load on knee extensors. Furthermore, STS in patients with knee OA had reduced energy absorption in the knee extensors from the shank forward lean movement after buttocks-off, had reduced knee extensor efficiency, and made greater use of physiological energy. These findings suggest that, from the standpoint of mechanical energy transfer, patients with knee OA do not perform STS efficiently. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of step length and step frequency on lower-limb muscle function in human gait.

PubMed

Lim, Yoong Ping; Lin, Yi-Chung; Pandy, Marcus G

2017-05-24

The aim of this study was to quantify the effects of step length and step frequency on lower-limb muscle function in walking. Three-dimensional gait data were used in conjunction with musculoskeletal modeling techniques to evaluate muscle function over a range of walking speeds using prescribed combinations of step length and step frequency. The body was modeled as a 10-segment, 21-degree-of-freedom skeleton actuated by 54 muscle-tendon units. Lower-limb muscle forces were calculated using inverse dynamics and static optimization. We found that five muscles - GMAX, GMED, VAS, GAS, and SOL - dominated vertical support and forward progression independent of changes made to either step length or step frequency, and that, overall, changes in step length had a greater influence on lower-limb joint motion, net joint moments and muscle function than step frequency. Peak forces developed by the uniarticular hip and knee extensors, as well as the normalized fiber lengths at which these muscles developed their peak forces, correlated more closely with changes in step length than step frequency. Increasing step length resulted in larger contributions from the hip and knee extensors and smaller contributions from gravitational forces (limb posture) to vertical support. These results provide insight into why older people with weak hip and knee extensors walk more slowly by reducing step length rather than step frequency and also help to identify the key muscle groups that ought to be targeted in exercise programs designed to improve gait biomechanics in older adults. Copyright © 2017 Elsevier Ltd. All rights reserved.

Twelve-week combined resistance and aerobic training confers greater benefits than aerobic training alone in nondialysis CKD.

PubMed

Watson, Emma L; Gould, Douglas W; Wilkinson, Thomas J; Xenophontos, Soteris; Clarke, Amy L; Vogt, Barbara Perez; Viana, João L; Smith, Alice C

2018-06-01

There is a growing consensus that patients with chronic kidney disease (CKD) should engage in regular exercise, but there is a lack of formal guidelines. In this report, we determined whether combined aerobic and resistance exercise would elicit superior physiological gains, in particular muscular strength, compared with aerobic training alone in nondialysis CKD. Nondialysis patients with CKD stages 3b-5 were randomly allocated to aerobic exercise {AE, n = 21; 9 men; median age 63 [interquartile range (IQR) 58-71] yr; median estimated glomerular filtration rate (eGFR) 24 (IQR 20-30) ml·min -1 ·1.73 m -2 } or combined exercise [CE, n = 20, 9 men, median age 63 (IQR 51-69) yr, median eGFR 27 (IQR 22-32) ml·min -1 ·1.73 m -2 ], preceded by a 6-wk run-in control period. Patients then underwent 12 wk of supervised AE (treadmill, rowing, or cycling exercise) or CE training (as AE plus leg extension and leg press exercise) performed three times per week. Outcome assessments of knee extensor muscle strength, quadriceps muscle volume, exercise capacity, and central hemodynamics were performed at baseline, following the 6-wk control period, and at the end of the intervention. AE and CE resulted in significant increases in knee extensor strength of 16 ± 19% (mean ± SD; P = 0.001) and 48 ± 37% ( P < 0.001), respectively, which were greater after CE ( P = 0.02). AE and CE resulted in 5 ± 7% ( P = 0.04) and 9 ± 7% ( P < 0.001) increases in quadriceps volume, respectively ( P < 0.001), which were greater after CE ( P = 0.01). Both AE and CE increased distance walked in the incremental shuttle walk test [28 ± 44 m ( P = 0.01) and 32 ± 45 m ( P = 0.01), respectively]. In nondialysis CKD, the addition of resistance exercise to aerobic exercise confers greater increases in muscle mass and strength than aerobic exercise alone.

The acute effect of Quercetin on muscle performance following a single resistance training session.

PubMed

Patrizio, Federica; Ditroilo, Massimiliano; Felici, Francesco; Duranti, Guglielmo; De Vito, Giuseppe; Sabatini, Stefania; Sacchetti, Massimo; Bazzucchi, Ilenia

2018-05-01

To examine the effect of acute quercetin (Q) ingestion on neuromuscular function, biomarkers of muscle damage, and rate of perceived exertion (RPE) in response to an acute bout of resistance training. 10 young men (22.1 ± 1.8 years, 24.1 ± 3.1 BMI) participated in a randomized, double-blind, crossover study. Subjects consumed Q (1 g/day) or placebo (PLA) 3 h prior to a resistance training session which consisted of 3 sets of 8 repetitions at 80% of the one repetition maximum (1RM) completed bilaterally for eight different resistance exercises. Electromyographic (EMG) signals were recorded from the knee extensor muscles during maximal isometric (MVIC) and isokinetic voluntary contractions, and during an isometric fatiguing test. Mechanical and EMG signals, biomarkers of cell damage, and RPE score were measured PRE, immediately POST, and 24 h (blood indices only) following the resistance exercise. After a single dose of Q, the torque-velocity curve of knee extensors was enhanced and after the resistance exercise, subjects showed a lower MVIC reduction (Q: 0.91 ± 6.10%, PLA: 8.66 ± 5.08%) with a greater rate of torque development (+ 10.6%, p < 0.005) and neuromuscular efficiency ratio (+ 28.2%, p < 0.005). Total volume of the resistance exercises was significantly greater in Q (1691.10 ± 376.71 kg rep) compared to PLA (1663.65 ± 378.85 kg rep) (p < 0.05) with a comparable RPE score. No significant differences were found in blood marker between treatments. The acute ingestion of Q may enhance the neuromuscular performance during and after a resistance training session.

Test-Retest Reliability of Rating of Perceived Exertion and Agreement With 1-Repetition Maximum in Adults.

PubMed

Bove, Allyn M; Lynch, Andrew D; DePaul, Samantha M; Terhorst, Lauren; Irrgang, James J; Fitzgerald, G Kelley

2016-09-01

Study Design Clinical measurement. Background It has been suggested that rating of perceived exertion (RPE) may be a useful alternative to 1-repetition maximum (1RM) to determine proper resistance exercise dosage. However, the test-retest reliability of RPE for resistance exercise has not been determined. Additionally, prior research regarding the relationship between 1RM and RPE is conflicting. Objectives The purpose of this study was to (1) determine test-retest reliability of RPE related to resistance exercise and (2) assess agreement between percentages of 1RM and RPE during quadriceps resistance exercise. Methods A sample of participants with and without knee pathology completed a series of knee extension exercises and rated the perceived difficulty of each exercise on a 0-to-10 RPE scale, then repeated the procedure 1 to 2 weeks later for test-retest reliability. To determine agreement between RPE and 1RM, participants completed knee extension exercises at various percentages of their 1RM (10% to 130% of predicted 1RM) and rated the perceived difficulty of each exercise on a 0-to-10 RPE scale. Percent agreement was calculated between the 1RM and RPE at each resistance interval. Results The intraclass correlation coefficient indicated excellent test-retest reliability of RPE for quadriceps resistance exercises (intraclass correlation coefficient = 0.895; 95% confidence interval: 0.866, 0.918). Overall percent agreement between RPE and 1RM was 60%, but agreement was poor within the ranges that would typically be used for training (50% 1RM for muscle endurance, 70% 1RM and greater for strength). Conclusion Test-retest reliability of perceived exertion during quadriceps resistance exercise was excellent. However, agreement between the RPE and 1RM was poor, especially in common training zones for knee extensor strengthening. J Orthop Sports Phys Ther 2016;46(9):768-774. Epub 5 Aug 2016. doi:10.2519/jospt.2016.6498.

The effects of a muscle resistance program on the functional capacity, knee extensor muscle strength and plasma levels of IL-6 and TNF-alpha in pre-frail elderly women: a randomized crossover clinical trial--a study protocol.

PubMed

Lustosa, Lygia P; Coelho, Fernanda M; Silva, Juscelio P; Pereira, Daniele S; Parentoni, Adriana N; Dias, João M D; Dias, Rosangela C; Pereira, Leani S M

2010-07-28

With the increase in the elderly population, a growing number of chronic degenerative diseases and a greater dependency on caregivers have been observed. Elderly persons in states of frailty remain more susceptible to significant health complications. There is evidence of an inverse relationship between plasma levels of inflammatory mediators and levels of functionality and muscle strength, suggesting that muscle-strengthening measures can aid in inflammatory conditions. The purpose of this study will be verified the effect of a muscle-strengthening program with load during a ten-week period in pre-frail elderly women with attention to the following outcomes: (1) plasma levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), (2) functional capacity and (3) knee extensor muscle strength. The study design is a randomized crossover clinical trial evaluating 26 elderly women (regardless of their race and/or social condition) who are community residents, older than 65, and classified as pre-frail according to the criteria previously described by Fried et al. (2004). All subjects will be assessed using the Timed up and go and 10-Meter Walk Test functional tests. The plasma levels of IL-6 and TNF-alpha will be assessed by ELISA (enzyme-linked immunosorbent assay) with high sensitivity kits (QuantikineHS, R&D Systems Minneapolis, MN, U.S.). Knee extensor muscle strength will be assessed using the Byodex System 3 Pro(R) isokinetic dynamometer at angular speeds of 60 and 180 degrees/s. The intervention will consist of strengthening exercises of the lower extremities at 50 to 70% of 1RM (maximal resistance) three times per week for ten weeks. The volunteers will be randomized into two groups: group E, the intervention group, and group C, the control group that did not initiate any new activities during the initial study period (ten weeks). After the initial period, group C will begin the intervention and group E will maintain everyday activities without exercising. At the end of the total study period, all volunteers will be reassessed. To demonstrate and discuss possible influences of load-bearing exercises on the modification of plasma levels of IL-6 and TNF-alpha and in the functional performance of pre-frail elderly women. ISRCTN62824599.

Effectiveness of a home-based strengthening program for elderly males in Italy. A preliminary study.

PubMed

Capodaglio, P; Facioli, M; Burroni, E; Giordano, A; Ferri, A; Scaglioni, G

2002-02-01

The practice of regular physical exercise has been shown to be effective in slowing the age-related progressive functional deterioration. Most exercise trials have been conducted with supervised training programs. The purpose of this study was to investigate the effectiveness of a 4-month home-based strength training on strength, function and personal satisfaction. Ten elderly men (mean age 68.5 years) were enrolled for home-based training one month after completing a 4-month supervised program; 12 age-matched men served as the control group. Subjects were asked to perform 3 sessions a week consisting of six resistance exercises with elastic bands involving the major muscle groups of the upper and lower limbs. We had calculated the correlation between the elongation and resistance of the elastic bands. The subjects were instructed to keep a diary reporting the execution of the session. We measured dynamic concentric strength of the muscle groups involved in the resistance exercises and maximal isometric strength of the knee extensors and elbow flexors before and after the 4-month home training. The Satisfaction Profile (SAT-P) questionnaire was administered before and one month after the completion of the training program for assessing personal satisfaction. The final to baseline comparison showed a non-significant decrease in mean isometric maximal strength values for knee extensors and elbow flexors in the control group, while the exercise group significantly (p=0.001) improved the average baseline values. Maximal dynamic concentric strength values decreased significantly in the control group, while significant improvements were observed in the exercising subjects. The SAT-P questionnaire did not show any difference in either group from baseline. The adherence-to-protocol rate based on self-report was 78%. Home training with elastic bands appears to be an effective low-cost modality of maintaining strength and function in an elderly population.

Long-term effects of a very low-carbohydrate weight loss diet on exercise capacity and tolerance in overweight and obese adults.

PubMed

Wycherley, Thomas P; Buckley, Jonathan D; Noakes, Manny; Clifton, Peter M; Brinkworth, Grant D

2014-01-01

Compare the long-term effects of an energy-restricted very low-carbohydrate, high-fat (LC) diet with an isocaloric high-carbohydrate, low-fat (HC) diet on exercise tolerance and capacity in overweight and obese adults. Seventy-six adults (25 males; age 49.2 ± 1.1 years; BMI 33.6 ± 0.5 kg/m(2)) were randomized to either a hypocaloric (6-7 MJ/day) LC diet (35% protein, 4% carbohydrate, 61% fat) or isocaloric HC diet (24% protein, 46% carbohydrate, 30% fat) for 52 weeks. Pre- and postintervention, participants' body weight and composition, handgrip, and isometric knee extensor strength were assessed and participants performed an incremental exercise test to exhaustion. Forty-three participants completed the study (LC = 23; HC = 20). Overall, peak relative oxygen uptake increased (+11.3%) and reductions occurred in body weight (-14.6%), body fat percentage (-6.9% [absolute]), isometric knee extensor strength (-12.4%), handgrip strength (-4.5%), and absolute peak oxygen uptake (-5.2%; p ≤ 0.02 time for all) with no diet effect (p ≥ 0.18). During submaximal exercise, rating of perceived exertion did not change in either group (p = 0.16 time, p = 0.59 Time × Group). Compared to the HC diet, the LC diet had greater reductions in respiratory exchange ratio (LC -0.04 ± 0.01, HC -0.00 ± 0.01; p = 0.03), and increased fat oxidation (LC 15.0 ± 5.3% [of energy expenditure], HC 0.5 ± 3.9%; p = 0.04). In overweight and obese patients, an LC diet promoted greater fat utilization during submaximal exercise. Both an LC diet and an HC diet had similar effects on aerobic capacity and muscle strength, suggesting that long-term consumption of an LC weight loss diet does not adversely affect physical function or the ability to perform exercise.

Weight-loss and exercise for communities with arthritis in North Carolina (we-can): design and rationale of a pragmatic, assessor-blinded, randomized controlled trial.

PubMed

Messier, Stephen P; Callahan, Leigh F; Beavers, Daniel P; Queen, Kate; Mihalko, Shannon L; Miller, Gary D; Losina, Elena; Katz, Jeffrey N; Loeser, Richard F; Quandt, Sara A; DeVita, Paul; Hunter, David J; Lyles, Mary F; Newman, Jovita; Hackney, Betsy; Jordan, Joanne M

2017-02-22

Recently, we determined that in a rigorously monitored environment an intensive diet-induced weight loss of 10% combined with exercise was significantly more effective at reducing pain in men and women with symptomatic knee osteoarthritis (OA) than either intervention alone. Compared to previous long-term weight loss and exercise trials of knee OA, our intensive diet-induced weight loss and exercise intervention was twice as effective at reducing pain intensity. Whether these results can be generalized to less intensively monitored cohorts is unknown. Thus, the policy relevant and clinically important question is: Can we adapt this successful solution to a pervasive public health problem in real-world clinical and community settings? This study aims to develop a systematic, practical, cost-effective diet-induced weight loss and exercise intervention implemented in community settings and to determine its effectiveness in reducing pain and improving other clinical outcomes in persons with knee OA. This is a Phase III, pragmatic, assessor-blinded, randomized controlled trial. Participants will include 820 ambulatory, community-dwelling, overweight and obese (BMI ≥ 27 kg/m 2 ) men and women aged ≥ 50 years who meet the American College of Rheumatology clinical criteria for knee OA. The primary aim is to determine whether a community-based 18-month diet-induced weight loss and exercise intervention based on social cognitive theory and implemented in three North Carolina counties with diverse residential (from urban to rural) and socioeconomic composition significantly decreases knee pain in overweight and obese adults with knee OA relative to a nutrition and health attention control group. Secondary aims will determine whether this intervention improves self-reported function, health-related quality of life, mobility, and is cost-effective. Many physicians who treat people with knee OA have no practical means to implement weight loss and exercise treatments as recommended by numerous OA treatment guidelines. This study will establish the effectiveness of a community program that will serve as a blueprint and exemplar for clinicians and public health officials in urban and rural communities to implement a diet-induced weight loss and exercise program designed to reduce knee pain and improve other clinical outcomes in overweight and obese adults with knee OA. clinicaltrials.gov Identifier: NCT02577549 October 12, 2015.

Ballistic movements of jumping legs implemented as variable components of cricket behaviour.

PubMed

Hustert, R; Baldus, M

2010-12-01

Ballistic accelerations of a limb or the whole body require special joint mechanisms in many animals. Specialized joints can be moved by stereotypic or variable motor control during motor patterns with and without ballistic components. As a model of variable motor control, the specialized femur-tibia (knee) joints of cricket (Acheta domesticus) hindlegs were studied during ballistic kicking, jumping and swimming and in non-ballistic walking. In this joint the tendons of the antagonistic flexor and the extensor muscles attach at different distances from the pivot and the opposed lever arms form an angle of 120 deg. A 10:1 ratio of their effective lever arms at full knee flexion helps to prepare for most ballistic extensions: the tension of the extensor can reach its peak while it is restrained by flexor co-contraction. In kicks, preparatory flexion is rapid and the co-contraction terminates just before knee extensions. Therefore, mainly the stored tension of the extensor muscle accelerates the small mass of the tibia. Jumps are prepared with slower extensor-flexor co-contractions that flex both knees simultaneously and then halt to rotate both legs outward to a near horizontal level. From there, catapult extension of both knees accelerates the body, supported by continued high frequency motor activity to their tibia extensor muscles during the ongoing push-off from the substrate. Premature extension of one knee instantly takes load from the lagging leg that extends and catches up, which finally results in a straight jump. In swimming, synchronous ballistic power strokes of both hindlegs drive the tibiae on a ventral-to-posterior trajectory through the water, well coordinated with the swimming patterns of all legs. In walking, running and climbing the steps of the hindlegs range between 45 deg flexion and 125 deg extension and use non-ballistic, alternating activity of knee flexor and extensor muscles. Steep climbing requires longer bursts from the extensor tibiae muscles when they support the extended hindlegs against gravity forces when the body hangs over. All ballistic movements of cricket knees are elicited by a basic but variable motor pattern: knee flexions by co-contraction of the antagonists prepare catapult extensions with speeds and forces as required in the different behaviours.

Speed, not magnitude, of knee extensor torque production is associated with self-reported knee function early after anterior cruciate ligament reconstruction.

PubMed

Hsieh, Chao-Jung; Indelicato, Peter A; Moser, Michael W; Vandenborne, Krista; Chmielewski, Terese L

2015-11-01

To examine the magnitude and speed of knee extensor torque production at the initiation of advanced anterior cruciate ligament (ACL) reconstruction rehabilitation and the associations with self-reported knee function. Twenty-eight subjects who were 12 weeks post-ACL reconstruction and 28 age- and sex-matched physically active controls participated in this study. Knee extensor torque was assessed bilaterally with an isokinetic dynamometer at 60°/s. The variables of interest were peak torque, average rate of torque development, time to peak torque and quadriceps symmetry index. Knee function was assessed with the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF). Peak torque and average rate of torque development were lower on the surgical side compared to the non-surgical side and controls. Quadriceps symmetry index was lower in subjects with ACL reconstruction compared to controls. On the surgical side, average rate of torque development was positively correlated with IKDC-SKF score (r = 0.379) while time to peak torque was negatively correlated with IKDC-SKF score (r = -0.407). At the initiation of advanced ACL reconstruction rehabilitation, the surgical side displayed deficits in peak torque and average rate of torque development. A higher rate of torque development and shorter time to peak torque were associated with better self-reported knee function. The results suggest that the rate of torque development should be addressed during advanced ACL reconstruction rehabilitation and faster knee extensor torque generation may lead to better knee function. III.

Genome-wide linkage scan for contraction velocity characteristics of knee musculature in the Leuven Genes for Muscular Strength Study.

PubMed

De Mars, Gunther; Windelinckx, An; Huygens, Wim; Peeters, Maarten W; Beunen, Gaston P; Aerssens, Jeroen; Vlietinck, Robert; Thomis, Martine A I

2008-09-17

The torque-velocity relationship is known to be affected by ageing, decreasing its protective role in the prevention of falls. Interindividual variability in this torque-velocity relationship is partly determined by genetic factors (h(2): 44-67%). As a first attempt, this genome-wide linkage study aimed to identify chromosomal regions linked to the torque-velocity relationship of the knee flexors and extensors. A selection of 283 informative male siblings (17-36 yr), belonging to 105 families, was used to conduct a genome-wide SNP-based (Illumina Linkage IVb panel) multipoint linkage analysis for the torque-velocity relationship of the knee flexors and extensors. The strongest evidence for linkage was found at 15q23 for the torque-velocity slope of the knee extensors (TVSE). Other interesting linkage regions with LOD scores >2 were found at 7p12.3 [logarithm of the odds ratio (LOD) = 2.03, P = 0.0011] for the torque-velocity ratio of the knee flexors (TVRF), at 2q14.3 (LOD = 2.25, P = 0.0006) for TVSE, and at 4p14 and 18q23 for the torque-velocity ratio of the knee extensors TVRE (LOD = 2.23 and 2.08; P = 0.0007 and 0.001, respectively). We conclude that many small contributing genes are involved in causing variation in the torque-velocity relationship of the knee flexor and extensor muscles. Several earlier reported candidate genes for muscle strength and muscle mass and new candidates are harbored within or in close vicinity of the linkage regions reported in the present study.

High intensity interval training does not impair strength gains in response to resistance training in premenopausal women.

PubMed

Gentil, Paulo; de Lira, Claudio Andre Barbosa; Filho, Suedi Gonçalves Cardoso; La Scala Teixeira, Cauê Vazquez; Steele, James; Fisher, James; Carneiro, Juliana Alves; Campos, Mário Hebling

2017-06-01

To compare the increases in upper- and lower-body muscle strength in premenopausal women performing resistance training (RT) alone or alongside concurrent high-intensity interval training (CT). Sixteen women (26-40 years) were randomly assigned into two groups that performed either RT or CT. Both groups performed the same RT program; however, CT performed additional high-intensity interval training (HIIT) on a bicycle ergometer before RT. The study lasted 8 weeks and the participants were tested for ten repetition maximum (10RM) load in elbow flexion (barbell biceps curl) and knee extension exercises pre- and post-intervention. RT was performed with 10-12 repetitions to self-determined repetition maximum in the first four weeks and then progressed to 8-10. During CT, HIIT was performed before RT with six 1-min bouts at 7-8 of perceived subjective exertion (RPE) and then progressed to eight bouts at 9-10 RPE. Analysis of variance revealed significant increases in upper and lower body strength for both the RT and CT groups. Biceps barbell curl 10RM load increased from 12.9 ± 3.2 kg to 14 ± 1.5 kg in CT (p < 0.05) and from 13 ± 1.8 kg to 15.9 ± 2.5 kg in RT (p < 0.05), with no significant between-groups differences. Knee extension 10RM increase from 31.9 ± 11.6 kg to 37.5 ± 8.5 kg for CT (p < 0.05) and from 30.6 ± 8.6 kg to 41.2 ± 7.4 kg for RT (p < 0.05). In conclusion, performing HIIT on a cycle ergometer before resistance training does not seem to impair muscle strength increases in the knee extensors or elbow flexors of pre-menopausal women. This information should be considered when prescribing exercise sessions, since both activities may be combined without negative effects in muscle strength.

Recovery Kinetics of Knee Flexor and Extensor Strength after a Football Match

PubMed Central

Draganidis, Dimitrios; Chatzinikolaou, Athanasios; Avloniti, Alexandra; Barbero-Álvarez, José C.; Mohr, Magni; Malliou, Paraskevi; Gourgoulis, Vassilios; Deli, Chariklia K.; Douroudos, Ioannis I.; Margonis, Konstantinos; Gioftsidou, Asimenia; Fouris, Andreas D.; Jamurtas, Athanasios Z.; Koutedakis, Yiannis; Fatouros, Ioannis G.

2015-01-01

We examined the temporal changes of isokinetic strength performance of knee flexor (KF) and extensor (KE) strength after a football match. Players were randomly assigned to a control (N = 14, participated only in measurements and practices) or an experimental group (N = 20, participated also in a football match). Participants trained daily during the two days after the match. Match and training overload was monitored with GPS devices. Venous blood was sampled and muscle damage was assessed pre-match, post-match and at 12h, 36h and 60h post-match. Isometric strength as well as eccentric and concentric peak torque of knee flexors and extensors in both limbs (dominant and non-dominant) were measured on an isokinetic dynamometer at baseline and at 12h, 36h and 60h after the match. Functional (KFecc/KEcon) and conventional (KFcon/KEcon) ratios were then calculated. Only eccentric peak torque of knee flexors declined at 60h after the match in the control group. In the experimental group: a) isometric strength of knee extensors and knee flexors declined (P<0.05) at 12h (both limbs) and 36h (dominant limb only), b) eccentric and concentric peak torque of knee extensors and flexors declined (P<0.05) in both limbs for 36h at 60°/s and for 60h at 180°/s with eccentric peak torque of knee flexors demonstrating a greater (P<0.05) reduction than concentric peak torque, c) strength deterioration was greater (P<0.05) at 180°/s and in dominant limb, d) the functional ratio was more sensitive to match-induced fatigue demonstrating a more prolonged decline. Discriminant and regression analysis revealed that strength deterioration and recovery may be related to the amount of eccentric actions performed during the match and athletes' football-specific conditioning. Our data suggest that recovery kinetics of knee flexor and extensor strength after a football match demonstrate strength, limb and velocity specificity and may depend on match physical overload and players' physical conditioning level. PMID:26043222

Identifying potential working mechanisms behind the positive effects of exercise therapy on pain and function in osteoarthritis; a systematic review.

PubMed

Runhaar, J; Luijsterburg, P; Dekker, J; Bierma-Zeinstra, S M A

2015-07-01

Although physical exercise is the commonly recommended for osteoarthritis (OA) patients, the working mechanism behind the positive effects of physical exercise on pain and function is a black box phenomenon. In the present study we aimed to identify possible mediators in the relation between physical exercise and improvements of pain and function in OA patients. A systematic search for all studies evaluating the effects of physical exercise in OA patients and select those that additionally reported the change in any physiological factor from pre-to post-exercise. In total, 94 studies evaluating 112 intervention groups were included. Most included studies evaluated subjects with solely knee OA (96 out of 112 groups). Based on the measured physiological factors within the included studies, 12 categories of possible mediators were formed. Muscle strength and ROM/flexibility were the most measured categories of possible mediators with 61 and 21 intervention groups measuring one or more physiological factors within these categories, respectively. 60% (31 out of 52) of the studies showed a significant increase in knee extensor muscle strength and 71% (22 out of 31) in knee flexor muscle strength over the intervention period. All 5 studies evaluating extension impairments and 10 out of 12 studies (83%) measuring proprioception found a significant change from pre-to post-intervention. An increase of upper leg strength, a decrease of extension impairments and improvement in proprioception were identified as possible mediators in the positive association between physical exercise and OA symptoms. Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

ASSOCIATION OF ISOMETRIC STRENGTH OF HIP AND KNEE MUSCLES WITH INJURY RISK IN HIGH SCHOOL CROSS COUNTRY RUNNERS.

PubMed

Luedke, Lace E; Heiderscheit, Bryan C; Williams, D S Blaise; Rauh, Mitchell J

2015-11-01

High school cross country runners have a high incidence of overuse injuries, particularly to the knee and shin. As lower extremity strength is modifiable, identification of strength attributes that contribute to anterior knee pain (AKP) and shin injuries may influence prevention and management of these injuries. To determine if a relationship existed between isometric hip abductor, knee extensor and flexor strength and the incidence of AKP and shin injury in high school cross country runners. Sixty-eight high school cross country runners (47 girls, 21 boys) participated in the study. Isometric strength tests of hip abductors, knee extensors and flexors were performed with a handheld dynamometer. Runners were prospectively followed during the 2014 interscholastic cross country season for occurrences of AKP and shin injury. Bivariate logistic regression was used to examine risk relationships between strength values and occurrence of AKP and shin injury. During the season, three (4.4%) runners experienced AKP and 13 (19.1%) runners incurred a shin injury. Runners in the tertiles indicating weakest hip abductor (chi-square = 6.140; p=0.046), knee extensor (chi-square = 6.562; p=0.038), and knee flexor (chi-square = 6.140; p=0.046) muscle strength had a significantly higher incidence of AKP. Hip and knee muscle strength was not significantly associated with shin injury. High school cross country runners with weaker hip abductor, knee extensor and flexor muscle strength had a higher incidence of AKP. Increasing hip and knee muscle strength may reduce the likelihood of AKP in high school cross country runners. 2b.

Countermeasures for Maintenance of Cardiovascular and Muscle Function in Space Flight

NASA Technical Reports Server (NTRS)

1997-01-01

In this session, Session FA2, the discussion focuses on the following topics: Effects of Repeated Long Duration +2Gz Load on Man's Cardiovascular Function; Certain Approaches to the Development of On-Board Automated Training System; Cardiac, Arterial, and Venous Adaptation to Og during 6 Month MIR-Spaceflights with and without "Thigh Cuffs" (93-95); Space Cycle(TM) Induced Physiologic Responses; Muscular Deconditioning During Long-term Spaceflight Exercise Recommendations to Optimize Crew Performance; Structure And Function of Knee Extensors After Long-Duration Spaceflight in Man, Effects of Countermeasure Exercise Training; Force and power characteristics of an exercise ergometer designed for use in space; and The simulating of overgravity conditions for astronauts' motor apparatus at the conditions of the training for orbital flights.

Strength of knee flexors of the paretic limb as an important determinant of functional status in post-stroke rehabilitation.

PubMed

Kostka, Joanna; Czernicki, Jan; Pruszyńska, Magdalena; Miller, Elżbieta

The purpose of the study was to assess the effectiveness of the multi-modal exercise program (MMEP) in patients after stroke, and to identify muscles that are the best predictors of functional performance and changes in functional status in a 3-week rehabilitation program. Thirty-one post-stroke patients (60.6±12.7 years) participating in a 3-week MMEP took part in the study. Measurements of extensor and flexor strength of the knee (F ext , F flex ) were done. Functional performance was measured using Timed Up & Go test (TUG), 6-Minute Walk Test (6-MWT) and Tinetti Test. The rehabilitation program improved all the results of functional tests, as well as the values of strength in the patients. Both baseline and post-rehabilitation functional status was associated with knee flexor and extensor muscle strength of paretic but not of non-paretic limbs. At baseline examination muscle strength difference between both F flex kg -1 and F ext kg -1 had an influence on functional status. After rehabilitation the effect of muscle strength difference on functional status was not evident for F ext kg -1 and, interestingly, even more prominent for F flex kg -1 . MMEP can effectively increase muscle strength and functional capacity in post-stroke patients. Knee flexor muscle strength of the paretic limb and the knee flexor difference between the limbs is the best predictor of functional performance in stroke survivors. Copyright © 2017 Polish Neurological Society. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Can an intensive diet and exercise program prevent knee pain among overweight adults at high risk?

PubMed

White, Daniel K; Neogi, Tuhina; Rejeski, W Jack; Walkup, Michael P; Lewis, Cora E; Nevitt, Michael C; Foy, Capri G; Felson, David T

2015-07-01

It is unclear whether an intensive program of weight loss combined with exercise prevents the onset of knee pain among those at high risk. We examined whether an intensive lifestyle intervention (ILI) prevents incident knee pain compared with a diabetes mellitus support and education (DSE) comparison group among overweight adults with diabetes mellitus. We conducted a secondary analysis of the Action for Health in Diabetes (Look AHEAD) study, which is a randomized intervention trial of adults who were obese and had type 2 diabetes mellitus starting in 2001. We studied a subcohort of 2,889 subjects who reported no knee pain at baseline but were at high risk due to obesity. Risk ratios (RRs) were calculated to examine the association of ILI versus DSE with incident knee pain at year 1 and year 4. All analyses were adjusted for potential confounders. Age, sex, and body mass index were similar among ILI and DSE participants with no knee pain at baseline. At year 1, ILI participants were 15% less likely to develop knee pain compared with DSE participants (RR 0.85, 95% confidence interval 0.74-0.98). At year 4, this difference decreased to 5% and was no longer statistically significant. An ILI of diet and exercise may prevent the development of knee pain among those at high risk in the short term. Health care providers may consider recommending diet and exercise as a means to prevent the development of knee pain among those at high risk. © 2015, American College of Rheumatology.

Effect of isometric quadriceps exercise on muscle strength, pain, and function in patients with knee osteoarthritis: a randomized controlled study.

PubMed

Anwer, Shahnawaz; Alghadir, Ahmad

2014-05-01

[Purpose] The aim of present study was to investigate the effects of isometric quadriceps exercise on muscle strength, pain, and function in knee osteoarthritis. [Subjects and Methods] Outpatients (N=42, 21 per group; age range 40-65 years; 13 men and 29 women) with osteoarthritis of the knee participated in the study. The experimental group performed isometric exercises including isometric quadriceps, straight leg raising, and isometric hip adduction exercise 5 days a week for 5 weeks, whereas the control group did not performed any exercise program. The outcome measures or dependent variables selected for this study were pain intensity, isometric quadriceps strength, and knee function. These variables were measured using the Numerical Rating Scale (NRS), strength gauge device, and reduced WOMAC index, respectively. All the measurements were taken at baseline (week 0) and at the end of the trial at week 5. [Results] In between-group comparisons, the maximum isometric quadriceps strength, reduction in pain intensity, and improvement in function in the isometric exercise group at the end of the 5th week were significantly greater than those of the control group (p<0.05). [Conclusion] The 5-week isometric quadriceps exercise program showed beneficial effects on quadriceps muscle strength, pain, and functional disability in patients with osteoarthritis of the knee.

Isokinetic knee joint evaluation in track and field events.

PubMed

Deli, Chariklia K; Paschalis, Vassilis; Theodorou, Anastasios A; Nikolaidis, Michalis G; Jamurtas, Athanasios Z; Koutedakis, Yiannis

2011-09-01

The purpose of this study was to evaluate maximal torque of the knee flexors and extensors, flexor/extensor ratios, and maximal torque differences between the 2 lower extremities in young track and field athletes. Forty male track and field athletes 13-17 years old and 20 male nonathletes of the same age participated in the study. Athletes were divided into 4 groups according to their age and event (12 runners and 10 jumpers 13-15 years old, 12 runners and 6 jumpers 16-17 years old) and nonathletes into 2 groups of the same age. Maximal torque evaluation of knee flexors and extensors was performed on an isokinetic dynamometer at 60°·s(-1). At the age of 16-17 years, jumpers exhibited higher strength values at extension than did runners and nonathletes, whereas at the age of 13-15 years, no significant differences were found between events. Younger athletes were weaker than older athletes at flexion. Runners and jumpers were stronger than nonathletes in all relative peak torque parameters. Nonathletes exhibited a higher flexor/extensor ratio compared with runners and jumpers. Strength imbalance in athletes was found between the 2 lower extremities in knee flexors and extensors and also at flexor/extensor ratio of the same extremity. Young track and field athletes exhibit strength imbalances that could reduce their athletic performance, and specific strength training for the weak extremity may be needed.

Relation between isokinetic muscle strength and functional capacity in recreational athletes with chondromalacia patellae.

PubMed

Yildiz, Y; Aydin, T; Sekir, U; Cetin, C; Ors, F; Alp Kalyon, T

2003-12-01

To investigate the effects of isokinetic exercise on pain and functional test scores of recreational athletes with chondromalacia patellae (CMP) and to examine the correlation between isokinetic parameters and functional tests or pain score. The functional ability of 30 recreational athletes with unilateral CMP was evaluated using six different tests. Pain scores were assessed during daily activities before and after the treatment protocol. Isokinetic exercise sessions were carried out at angular velocities of 60 degrees /s (25-90 degrees range of flexion) and 180 degrees /s (full range). These sessions were repeated three times a week for six weeks. Quadriceps and hamstring peak torque, total work, and endurance ratios had improved significantly after the treatment, as did the functional parameters and pain scores. There was a poor correlation between the extensor endurance ratio and one leg standing test. A moderate correlation between the visual analogue scale and the extensor endurance ratio or flexion endurance ratio was also found. The isokinetic exercise programme used in this study had a positive effect on muscle strength, pain score, and functional ability of knees with CMP. The improvement in the functional capacity did not correlate with the isokinetic parameters.

Isokinetic and Electromyographic Properties of Muscular Endurance in Short and Long-Term Type 2 Diabetes

PubMed Central

Hatef, Boshra; Ghanjal, Ali; Meftahi, Gholam Hossein; Askary-Ashtiani, Ahmadreza

2016-01-01

Background: Patients with type 2 diabetes mellitus (T2DM) are subject to progressive reduction of muscle mass and strength. The aim of this study was to assess muscle forces and electromyography (EMG) indices in short and long-term diabetes during an isokinetic exercise. Methods: The peak torque, work, mean power frequency (MPF) and root mean square (RMS) of knee flexors and extensors during 40 isokinetic knee extension-flexion repetitions with a velocity of 150 degree/s were recorded. 18 patients with less than 10 years with T2DM and 12 patients with equal and more than 10 years of disease were compared with 20 gender, body mass index, physical activity and peripheral circulation matched healthy controls. Results: The fatigue index and slope of line across the peak torque values of the knee flexor indicate that patients with long-term T2DM were significantly more resistant to fatigue in comparison with the two other groups (p<0.009). Whereas the MPF decrease during isokinetic protocol interact with grouping in the medial hamstring (p<0.042), but it was independent to groups in other muscles (p<0.0001). The increase of RMS after fatigue protocol interacted with sex for the medial hamstring and vastus lateralis (p<0.039) and interacted with group for the extensor muscles (p<0.045). Discussion & Conclusion: It seems that long-term T2DM cause some neuromuscular adaptations to maintain knee flexor muscle performance during functional activity especially postural control. PMID:27045412

Effects of a Short Physical Exercise Intervention on Patients with Multiple Sclerosis (MS).

PubMed

Kerling, Arno; Keweloh, Karin; Tegtbur, Uwe; Kück, Momme; Grams, Lena; Horstmann, Hauke; Windhagen, Anja

2015-07-10

The aim of this prospective randomized controlled trial was to investigate if a short-term endurance or combined endurance/resistance exercise program was sufficient to improve aerobic capacity and maximum force in adult patients (18-65 years) with multiple sclerosis (MS). All patients performed a three-month exercise program consisting of two training sessions per week, lasting 40 min each, with moderate intensity. All patients had a maximum value of 6 (low to moderate disability) on the Expanded Disability Status Scale (EDSS). One group (combined workout group (CWG); 15 females, 4 males) completed a combined endurance/resistance workout (20 min on a bicycle ergometer, followed by 20 min of resistance training), while the other group (endurance workout group (EWG); 13 females, 5 males) completed a 40 min endurance training program. Aerobic capacity was assessed as peak oxygen uptake, ventilatory anaerobic threshold, and workload expressed as Watts. Maximum force of knee and shoulder extensors and flexors was measured using isokinetic testing. Quality of life was assessed with the SF-36 questionnaire, and fatigue was measured using the Modified Fatigue Impact Scale. Both training groups increased in aerobic capacity and maximum force. EWG, as well as CWG, showed improvement in several subscales of the SF-36 questionnaire and decrease of their fatigue. A short exercise intervention increased both aerobic capacity and maximum force independent of whether endurance or combined endurance/resistance workouts were performed.

Assessment of the in-season changes in mechanical and neuromuscular characteristics in professional soccer players.

PubMed

García-García, Oscar; Serrano-Gómez, Virginia; Hernández-Mendo, Antonio; Tapia-Flores, Antonio

2016-06-01

The aim of this study was to monitor in-season changes in the mechanical and neuromuscular characteristics of knee extensor and flexor muscles in professional soccer players. Twenty-one professional soccer players (soccer group, or SG) and sixteen non-soccer playing males (non-soccer group, or NSG) were assessed by tensiomyography on two occasions: just after the start of the competitive season and 10 weeks later. During this time the soccer players' training sessions were built mainly on speed and strength drills. Mixed-design factorial analysis of variance was conducted and effect sizes were calculated. There was a significant interaction between time (assessment points) x group (SG vs. NSG) x muscle for contraction time (Tc), maximum radial muscle displacement (Dm), and delay time (Td). In the case of the knee extensors, after 10 weeks, there was a 17.7%-22.7% decrease in Tc, an 8.7%-9.9% decrease in Td, and a 12.2%-14.2% decrease in Dm knee extensor in the SG (P<0.01), with a large effect size. In the case of the knee flexors, by contrast, there was an 11.9% increase in Td and a 24.5% increase in Dm (P<0.01), with a moderate to large effect size. The findings confirm that mechanical and neuromuscular characteristics change over time and also vary according to the characteristics of the athlete (SG vs. NSG) and the muscle analyzed. In conclusion, soccer coaches could use Tc, Td, and Dm data to individualize work load and intensity and control the effects of neuromuscular training throughout the season using a portable, non-invasive technique that, unlike stress tests, does not cause fatigue and therefore does not interfere with training periodization.

Muscle torque and its relation to technique, tactics, sports level and age group in judo contestants.

PubMed

Lech, Grzegorz; Chwała, Wiesław; Ambroży, Tadeusz; Sterkowicz, Stanisław

2015-03-29

The aim of this study was to perform a comparative analysis of maximal muscle torques at individual stages of development of athletes and to determine the relationship between muscle torques, fighting methods and the level of sports performance. The activity of 25 judo contestants during judo combats and the effectiveness of actions were evaluated. Maximum muscle torques in flexors/extensors of the body trunk, shoulder, elbow, hip and knee joints were measured. The level of significance was set at p≤0.05; for multiple comparisons the Mann-Whitney U test, p≤0.016, was used. Intergroup differences in relative torques in five muscle groups studied (elbow extensors, shoulder flexors, knee flexors, knee extensors, hip flexors) were not significant. In cadets, relative maximum muscle torques in hip extensors correlated with the activity index (Spearman's r=0.756). In juniors, maximum relative torques in elbow flexors and knee flexors correlated with the activity index (r=0.73 and r=0.76, respectively). The effectiveness of actions correlated with relative maximum torque in elbow extensors (r=0.67). In seniors, the relative maximum muscle torque in shoulder flexors correlated with the activity index during the second part of the combat (r=0.821).

Muscle Torque and its Relation to Technique, Tactics, Sports Level and Age Group in Judo Contestants

PubMed Central

Lech, Grzegorz; Chwała, Wiesław; Ambroży, Tadeusz; Sterkowicz, Stanisław

2015-01-01

The aim of this study was to perform a comparative analysis of maximal muscle torques at individual stages of development of athletes and to determine the relationship between muscle torques, fighting methods and the level of sports performance. The activity of 25 judo contestants during judo combats and the effectiveness of actions were evaluated. Maximum muscle torques in flexors/extensors of the body trunk, shoulder, elbow, hip and knee joints were measured. The level of significance was set at p≤0.05; for multiple comparisons the Mann-Whitney U test, p≤0.016, was used. Intergroup differences in relative torques in five muscle groups studied (elbow extensors, shoulder flexors, knee flexors, knee extensors, hip flexors) were not significant. In cadets, relative maximum muscle torques in hip extensors correlated with the activity index (Spearman’s r=0.756). In juniors, maximum relative torques in elbow flexors and knee flexors correlated with the activity index (r=0.73 and r=0.76, respectively). The effectiveness of actions correlated with relative maximum torque in elbow extensors (r=0.67). In seniors, the relative maximum muscle torque in shoulder flexors correlated with the activity index during the second part of the combat (r=0.821). PMID:25964820

Physiological exercise loading suppresses post-traumatic osteoarthritis progression via an increase in bone morphogenetic proteins expression in an experimental rat knee model.

PubMed

Iijima, H; Ito, A; Nagai, M; Tajino, J; Yamaguchi, S; Kiyan, W; Nakahata, A; Zhang, J; Wang, T; Aoyama, T; Nishitani, K; Kuroki, H

2017-06-01

To evaluate the dose-response relationship of exercise loading in the cartilage-subchondral bone (SB) unit in surgically-induced post-traumatic osteoarthritis (PTOA) of the knee. Destabilized medial meniscus (DMM) surgery was performed on the right knee of 12-week-old male Wistar rats, and sham surgery was performed on the contralateral knee. Four weeks after the surgery, the animals were subjected to moderate (12 m/min) or intense (21 m/min) treadmill exercises for 30 min/day, 5 days/week for 4 weeks. PTOA development in articular cartilage and SB was examined using histological and immunohistochemical analyses, micro-computed tomography (micro-CT) analysis, and biomechanical testing at 8 weeks after surgery. Gremlin-1 was injected to determine the role of bone morphogenetic protein (BMP) signaling on PTOA development following moderate exercise. Moderate exercise increased BMP-2, BMP-4, BMP-6, BMP receptor 2, pSmad-5, and inhibitor of DNA binding protein-1 expression in the superficial zone chondrocytes and suppressed cartilage degeneration, osteophyte growth, SB damage, and osteoclast-mediated SB resorption. However, intense exercise had little effect on BMP expression and even caused progression of these osteoarthritis (OA) changes. Gremlin-1 injection following moderate exercise caused progression of the PTOA development down to the level of the non-exercise DMM-operated knee. Exercise regulated cartilage-SB PTOA development in DMM-operated knees in a dose-dependent manner. Our findings shed light on the important role of BMP expression in superficial zone chondrocytes in attenuation of PTOA development following physiological exercise loading. Further studies to support a mechanism by which BMPs would be beneficial in preventing PTOA progression are warranted. Copyright © 2016 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Impaired Skeletal Muscle Vasodilation during Exercise in Heart Failure with Preserved Ejection Fraction

PubMed Central

Lee, Joshua F.; Barrett-O’Keefe, Zachary; Nelson, Ashley D.; Garten, Ryan S.; Ryan, John J.; Nativi-Nicolau, Jose N.; Richardson, Russell S.; Wray, D. Walter

2016-01-01

Background Exercise intolerance is a hallmark symptom of heart failure patients with preserved ejection fraction (HFpEF), which may be related to an impaired ability to appropriately increase blood flow to the exercising muscle. Methods We evaluated leg blood flow (LBF, ultrasound Doppler), heart rate (HR), stroke volume (SV), cardiac output (CO), and mean arterial blood pressure (MAP, photoplethysmography) during dynamic, single leg knee-extensor (KE) exercise in HFpEF patients (n = 21; 68 ± 2 yrs) and healthy controls (n = 20; 71 ± 2 yrs). Results HFpEF patients exhibited a marked attrition during KE exercise, with only 60% able to complete the exercise protocol. In participants who completed all exercise intensities (0-5-10-15W; HFpEF, n = 13; Controls, n = 16), LBF was not different at 0W and 5W, but was 15-25% lower in HFpEF compared to controls at 10W and 15W (P < 0.001). Likewise, leg vascular conductance (LVC), an index of vasodilation, was not different at 0W and 5W, but was 15-20% lower in HFpEF compared to controls at 10W and 15W (P < 0.05). In contrast to these peripheral deficits, exercise-induced changes in central variables (HR, SV, CO), as well as MAP, were similar between groups. Conclusions These data reveal a marked reduction in LBF and LVC in HFpEF patients during exercise that cannot be attributed to a disease-related alteration in central hemodynamics, suggesting that impaired vasodilation in the exercising skeletal muscle vasculature may play a key role in the exercise intolerance associated with this patient population. PMID:26970959

Hip Abductor Strengthening Improves Physical Function Following Total Knee Replacement: One-Year Follow-Up of a Randomized Pilot Study.

PubMed

Harikesavan, Karvannan; Chakravarty, Raj D; Maiya, Arun G; Hegde, Sanjay P; Y Shivanna, Shivakumar

2017-01-01

Total knee replacement (TKR) is the commonest surgical procedure for patients with severe pain and impaired physical function following end stage knee osteoarthritis. The hip abductors are well renowned in stabilization of the trunk and hip during walking, maintaining the lower limb position, and transferring the forces from the lower limbs to the pelvis. To assess the efficacy of hip abductor strengthening exercise on functional outcome using performance based outcome measures following total knee replacement. An observer blinded randomized pilot trial design was conducted at Manipal hospital, Bangalore, India. Participants designated for elective TKR were randomized to experimental group hip abductor strengthening along with standard rehabilitation (n=10) or control group standard rehabilitation alone (n=10). Participants followed for one year to assess physical function using performance based outcomes, such as timed up and go test, single leg stance test, six minute walk test, knee extensor strength and hip abductor strength. Eighteen participants with a mean age of 63.1 ± 5.5 years (8 Males and 10 Females) completed the study. Improvement in hip abduction strength, single leg stand test was superior in hip abductor strengthening group at 3 months and 1 year when compared to standard rehabilitation alone. Hip abductor strengthening showed superior improvements in single leg stance test and six minute walk test. Hip abductor strengthening exercises has the potential to improve physical function following total knee replacement.

Hip Abductor Strengthening Improves Physical Function Following Total Knee Replacement: One-Year Follow-Up of a Randomized Pilot Study

PubMed Central

Harikesavan, Karvannan; Chakravarty, Raj D.; Maiya, Arun G; Hegde, Sanjay P.; Y. Shivanna, Shivakumar

2017-01-01

Background: Total knee replacement (TKR) is the commonest surgical procedure for patients with severe pain and impaired physical function following end stage knee osteoarthritis. The hip abductors are well renowned in stabilization of the trunk and hip during walking, maintaining the lower limb position, and transferring the forces from the lower limbs to the pelvis. Objective: To assess the efficacy of hip abductor strengthening exercise on functional outcome using performance based outcome measures following total knee replacement. Methods: An observer blinded randomized pilot trial design was conducted at Manipal hospital, Bangalore, India. Participants designated for elective TKR were randomized to experimental group hip abductor strengthening along with standard rehabilitation (n=10) or control group standard rehabilitation alone (n=10). Participants followed for one year to assess physical function using performance based outcomes, such as timed up and go test, single leg stance test, six minute walk test, knee extensor strength and hip abductor strength. Result: Eighteen participants with a mean age of 63.1 ± 5.5 years (8 Males and 10 Females) completed the study. Improvement in hip abduction strength, single leg stand test was superior in hip abductor strengthening group at 3 months and 1 year when compared to standard rehabilitation alone. Conclusion: Hip abductor strengthening showed superior improvements in single leg stance test and six minute walk test. Hip abductor strengthening exercises has the potential to improve physical function following total knee replacement. PMID:28567148

The effect of whole-body vibration therapy on bone metabolism, motor function, and anthropometric parameters in women with postmenopausal osteoporosis.

PubMed

Luo, Xiaotian; Zhang, Jifeng; Zhang, Chi; He, Chengqi; Wang, Pu

2017-11-01

To review the research literature on the effectiveness of whole-body vibration (WBV) therapy in women with postmenopausal osteoporosis. A systematic review was conducted by two independent reviewers. Mean differences (MDs), standardized mean differences (SMDs), and 95% confidence intervals (CIs) were calculated, and heterogeneity was assessed with the I 2 test. The Cochrane risk of bias tool was used to assess the methodological quality of the selected studies. Nine randomized controlled trials involving 625 patients met the inclusion criteria. No significant improvement was found in bone mineral density (BMD) (SMD = -0.06, 95%CI= -0.22-0.11, p = 0.50); bone turnover markers (MD = -0.25, 95%CI= -0.54-0.03, p = 0.08); anthropometric parameters, including muscle mass, fat mass, body mass index (BMI), and weight (SMD = 0.02, 95%CI= -0.16-0.21, p = 0.81); or maximal isotonic knee extensor strength (SMD = 0.16, 95%CI= -0.63-0.95, p = 0.69). However, maximal isometric knee extensor strength improved (SMD = 0.71, 95%CI = 0.34-1.08, p = 0.0002). WBV is beneficial for enhancing maximal isometric knee extensor strength, but it has no overall treatment effect on BMD, bone turnover markers, anthropometric parameters, or maximal isotonic knee extensor strength in women with postmenopausal osteoporosis. Implication of rehabilitation Osteoporosis is the leading underlying cause of fractures in postmenopausal women, whole body vibration (WBV) has received much attention as a potential intervention for the management of osteoporosis in recent years. Whole body vibration is beneficial for enhancing maximal isometric knee extensor strength in women with postmenopausal osteoporosis. Whole body vibration has no overall treatment effect on bone mineral density, bone turnover markers, anthropometric parameters and maximal isotonic knee extensor strength in women with postmenopausal osteoporosis.

Relationship between lower extremity isometric muscle strength and standing balance in patients with multiple sclerosis.

PubMed

Citaker, Seyit; Guclu-Gunduz, Arzu; Yazici, Gokhan; Bayraktar, Deniz; Nazliel, Bijen; Irkec, Ceyla

2013-01-01

Muscle strength and standing balance decrease in patients with Multiple Sclerosis (MS). The aim of the present study was to investigate the relationship between the lower extremity isometric muscle strength and standing balance in patients with MS. Forty-seven patients with MS and 10 healthy volunteers were included. Neurological disability level was assessed using Expanded Disability Status Scale (EDSS). Isometric strength of seven lower extremity muscles (hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor) was assessed using hand-held dynamometer. Duration of static one-leg standing balance was measured using digital chronometer. Hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor isometric muscle strength, and duration of one-leg standing balance were decreased in patients with MS when compared with controls (p < 0.05). All assessed lower extremity isometric muscle strength and EDSS level was related duration of one-leg standing balance in patients with MS. All assessed lower extremity isometric muscle strength (except ankle dorsal flexor) was related with EDSS. Hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor isometric muscle strength decreases in ambulatory MS patients. Lower extremity muscle weakness and neurological disability level are related with imbalance in MS population. Hip and knee region muscles weakness increases the neurological disability level. For the better balance and decrease neurological disability level whole lower extremity muscle strengthening should be included in rehabilitation programs.

Transcranial direct current stimulation improves isometric time to exhaustion of the knee extensors.

PubMed

Angius, L; Pageaux, B; Hopker, J; Marcora, S M; Mauger, A R

2016-12-17

Transcranial direct current stimulation (tDCS) can increase cortical excitability of a targeted brain area, which may affect endurance exercise performance. However, optimal electrode placement for tDCS remains unclear. We tested the effect of two different tDCS electrode montages for improving exercise performance. Nine subjects underwent a control (CON), placebo (SHAM) and two different tDCS montage sessions in a randomized design. In one tDCS session, the anodal electrode was placed over the left motor cortex and the cathodal on contralateral forehead (HEAD), while for the other montage the anodal electrode was placed over the left motor cortex and cathodal electrode above the shoulder (SHOULDER). tDCS was delivered for 10min at 2.0mA, after which participants performed an isometric time to exhaustion (TTE) test of the right knee extensors. Peripheral and central neuromuscular parameters were assessed at baseline, after tDCS application and after TTE. Heart rate (HR), ratings of perceived exertion (RPE), and leg muscle exercise-induced muscle pain (PAIN) were monitored during the TTE. TTE was longer and RPE lower in the SHOULDER condition (P<0.05). Central and peripheral parameters, and HR and PAIN did not present any differences between conditions after tDCS stimulation (P>0.05). In all conditions maximal voluntary contraction (MVC) significantly decreased after the TTE (P<0.05) while motor-evoked potential area (MEP) increased after TTE (P<0.05). These findings demonstrate that SHOULDER montage is more effective than HEAD montage to improve endurance performance, likely through avoiding the negative effects of the cathode on excitability. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Isometric strength training lowers the O2 cost of cycling during moderate-intensity exercise.

PubMed

Zoladz, Jerzy A; Szkutnik, Zbigniew; Majerczak, Joanna; Grandys, Marcin; Duda, Krzysztof; Grassi, Bruno

2012-12-01

The effect of maximal voluntary isometric strength training of knee extensor muscles on pulmonary V'O(2) on-kinetics, the O(2) cost of cycling and peak oxygen uptake (V'O(2peak)) in humans was studied. Seven healthy males (mean ± SD, age 22.3 ± 2.0 years, body weight 75.0 ± 9.2 kg, V'O(2peak) 49.5 ± 3.8 ml kg(-1) min(-1)) performed maximal isometric strength training lasting 7 weeks (4 sessions per week). Force during maximal voluntary contraction (MVC) increased by 15 % (P < 0.001) after 1 week of training, and by 19 % (P < 0.001) after 7 weeks of training. This increase in MVC was accompanied by no significant changes in the time constant of the V'O(2) on-kinetics during 6 min of moderate and heavy cycling intensities. Strength training resulted in a significant decrease (by ~7 %; P < 0.02) in the amplitude of the fundamental component of the V'O(2) on-kinetics, and therefore in a lower O(2) cost of cycling during moderate cycling intensity. The amplitude of the slow component of V'O(2) on-kinetics during heavy cycling intensity did not change with training. Training had no effect on the V'O(2peak), whereas the maximal power output reached at V'O(2peak) was slightly but significantly increased (P < 0.05). Isometric strength training rapidly (i.e., after 1 week) decreases the O(2) cost of cycling during moderate-intensity exercise, whereas it does not affect the amplitude of the slow component of the V'O(2) on-kinetics during heavy-intensity exercise. Isometric strength training can have beneficial effects on performance during endurance events.

Lower-extremity biomechanics during forward and lateral stepping activities in older adults

PubMed Central

Wang, Man-Ying; Flanagan, Sean; Song, Joo-Eun; Greendale, Gail A.; Salem, George J.

2012-01-01

Objective To characterize the lower-extremity biomechanics associated with stepping activities in older adults. Design Repeated-measures comparison of kinematics and kinetics associated with forward step-up and lateral step-up activities. Background Biomechanical analysis may be used to assess the effectiveness of various ‘in-home activities’ in targeting appropriate muscle groups and preserving functional strength and power in elders. Methods Data were analyzed from 21 participants (mean 74.7 yr (standard deviation, 4.4 yr)) who performed the forward and lateral step-up activities while instrumented for biomechanical analysis. Motion analysis equipment, inverse dynamics equations, and repeated measures anovas were used to contrast the maximum joint angles, peak net joint moments, angular impulse, work, and power associated with the activities. Results The lateral step-up resulted in greater maximum knee flexion (P < 0.001) and ankle dorsiflexion angles (P < 0.01). Peak joint moments were similar between exercises. The forward step-up generated greater peak hip power (P < 0.05) and total work (P < 0.001); whereas, the lateral step-up generated greater impulse (P < 0.05), work (P < 0.01), and power (P < 0.05) at the knee and ankle. Conclusions In older adults, the forward step-up places greater demand on the hip extensors, while lateral step-up places greater demand on the knee extensors and ankle plantar flexors. PMID:12620784

Effects of exercise on knee joints with osteoarthritis: a pilot study of biologic markers

NASA Technical Reports Server (NTRS)

Bautch, J. C.; Malone, D. G.; Vailas, A. C.

1997-01-01

OBJECTIVE: To determine the effects of low intensity weight-bearing exercise on osteoarthritis (OA) of the knee. METHODS: Synovial fluid keratan sulfate (KS) and hydroxyproline were measured as markers of cartilage degradation. The Arthritis Impact Measurement Scales (AIMS) were used to measure health status, and a visual analog scale for pain assessment was used before and after intervention. An exercise (EX) group (n = 15) received a thrice-weekly 12-week low intensity exercise program and a weekly educational program, and a minimal treatment (Min RX) group (n = 15) received only the education program. RESULTS: Pain levels declined in the EX group, and the Min RX group showed improvement on the AIMS. Synovial fluid was obtained in 11 subjects before and after the intervention. Levels of KS and hydroxyproline did not change. CONCLUSION: Further study of exercise effects should include both clinical and biologic parameters to examine the outcome of exercise as a therapeutic intervention in OA of the knee.

Effects of 17-day spaceflight on knee extensor muscle function and size

NASA Technical Reports Server (NTRS)

Tesch, Per A.; Berg, Hans E.; Bring, Daniel; Evans, Harlan J.; LeBlanc, Adrian D.

2005-01-01

It is generally held that space travelers experience muscle dysfunction and atrophy during exposure to microgravity. However, observations are scarce and reports somewhat inconsistent with regard to the time course, specificity and magnitude of such changes. Hence, we examined four male astronauts (group mean approximately 43 years, 86 kg and 183 cm) before and after a 17-day spaceflight (Space Transport System-78). Knee extensor muscle function was measured during maximal bilateral voluntary isometric and iso-inertial concentric, and eccentric actions. Cross-sectional area (CSA) of the knee extensor and flexor, and gluteal muscle groups was assessed by means of magnetic resonance imaging. The decrease in strength (P<0.05) across different muscle actions after spaceflight amounted to 10%. Eight ambulatory men, examined on two occasions 20 days apart, showed unchanged (P>0.05) muscle strength. CSA of the knee extensor and gluteal muscles, each decreased (P<0.05) by 8%. Knee flexor muscle CSA showed no significant (P>0.05) change. The magnitude of these changes concord with earlier results from ground-based studies of similar duration. The results of this study, however, do contrast with the findings of no decrease in maximal voluntary ankle plantar flexor force previously reported in the same crew.

Hip and knee extensor moments predict vertical jump height in adolescent girls.

PubMed

Ford, Kevin R; Myer, Gregory D; Brent, Jensen L; Hewett, Timothy E

2009-07-01

Biomechanical factors, such as hip and knee extensor moments, related to drop jump (DJ) performance have not been investigated in adolescent girls. The purpose of this study was to determine the key independent biomechanical variables that predict overall vertical jump performance in adolescent girls. Sixteen high school adolescent girls from club-sponsored and high school-sponsored volleyball teams performed DJ at 3 different drop heights (15, 30, and 45 cm). A motion analysis system consisting of 10 digital cameras and a force platform was used to calculate vertical jump height, joint angles, and joint moments during the tasks. A multiple linear regression was used to determine the biomechanical parameters that were best predictive of vertical jump height at each box drop distance. The 2 predictor variables in all 3 models were knee and hip extensor moments. The models predicted 82.9, 81.9, and 88% of the vertical jump height variance in the 15, 30, and 45 cm trials, respectively. The results of the investigation indicate that knee and hip joint moments are the main contributors to vertical jump height during the DJ in adolescent girls. Strength and conditioning specialists attempting to improve vertical jump performance should target power and strength training to the hip and knee extensors in their athletes.

Effects of Pilates on muscle strength, postural balance and quality of life of older adults: a randomized, controlled, clinical trial

PubMed Central

Campos de Oliveira, Laís; Gonçalves de Oliveira, Raphael; Pires-Oliveira, Deise Aparecida de Almeida

2015-01-01

[Purpose] The aim of the present study was to determine the effects of Pilates on lower leg strength, postural balance and the health-related quality of life (HRQoL) of older adults. [Subjects and Methods] Thirty-two older adults were randomly allocated either to the experimental group (EG, n = 16; mean age, 63.62 ± 1.02 years), which performed two sessions of Pilates per week for 12 weeks, or to the control group (CG, n = 16; mean age, 64.21 ± 0.80), which performed two sessions of static stretching per week for 12 weeks. The following evaluations were performed before and after the interventions: isokinetic torque of knee extensors and flexors at 300°/s, the Timed Up and Go (TUG) test, the Berg Balance Scale, and the Health Survey assessment (SF-36). [Results] In the intra-group analysis, the EG demonstrated significant improvement in all variables. In the inter-group analysis, the EG demonstrated significant improvement in most variables. [Conclusion] Pilates exercises led to significant improvement in isokinetic torque of the knee extensors and flexors, postural balance and aspects of the health-related quality of life of older adults. PMID:25931749

Effect of whole body vibration training on lower limb performance in selected high-level ballet students.

PubMed

Annino, Giuseppe; Padua, Elvira; Castagna, Carlo; Di Salvo, Valter; Minichella, Stefano; Tsarpela, Olga; Manzi, Vincenzo; D'Ottavio, Stefano

2007-11-01

The aim of this study was to examine the effects of 8 weeks of whole body vibration (WBV) training on vertical jump ability (CMJ) and knee-extensor performance at selected external loads (50, 70, and 100 kg; leg-press exercise) in elite ballerinas. Twenty-two (age, 21.25 +/- 1.5 years) full-time ballerinas were assigned randomly to the experimental (E, n = 11) and control (C, n = 11) groups. The experimental group was submitted to WBV training 3 times per week before ballet practice. During the training period, the E and C groups undertook the same amount of ballet practice. Posttraining CMJ performance significantly increased in E group (6.3 +/- 3.8%, p < 0.001). Furthermore, E group showed significant (p < 0.05-0.001) posttraining average leg-press power and velocity improvements at all the external loads considered. Consequently, the force-velocity and power-velocity relationship shifted to the right after WBV training in the E group. The results of the present study show that WBV training is an effective short-term training methodology for inducing improvements in knee-extensor explosiveness in elite ballerinas.

FUNCTIONAL PERFORMANCE AND KNEE LAXITY IN NORMAL INDIVIDUALS AND IN INDIVIDUALS SUBMITTED TO ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

PubMed Central

de Vasconcelos, Rodrigo Antunes; Bevilaqua-Grossi, Débora; Shimano, Antonio Carlos; Jansen Paccola, Cleber Antonio; Salvini, Tânia Fátima; Prado, Christiane Lanatovits; Mello Junior, Wilson A.

2015-01-01

The aim of this study was to analyze the correlation between deficits in the isokinetic peak torque of the knee extensors and flexors with hop tests, postoperative knee laxity and functional scores in normal and ACL- reconstructed subjects with patellar tendon and hamstring tendon autografts. Methods: Sixty male subjects were enrolled and subdivided into three groups: Twenty subjects without knee injuries (GC group) and two groups of 20 subjects submitted to ACL reconstruction with patellar tendon (GTP group) and hamstrings autograft (GTF group). Results: The results showed significant correlation between knee extensors peak torque and performance in the hop tests for GTF and GC groups. There are no significantly correlations between post op knee laxity and Lysholm score compared with the hop tests and peak torque deficits. Concerning the differences between groups, the GTP group showed greater peak torque deficits in knee extensors, worst Lysholm scores and higher percentage of individuals with lower limb symmetry index (ISM) < 90% in both hop tests when compared to the other two groups. Conclusion: It is not recommendable to use only one measurement instrument for the functional evaluation of ACL-reconstructed patients, because significant correlation between peak torque, subject's functional score, knee laxity and hop tests were not observed in all groups. PMID:26998464

Mildly disabled persons with multiple sclerosis use similar net joint power strategies as healthy controls when walking speed increases.

PubMed

Brincks, John; Christensen, Lars Ejsing; Rehnquist, Mette Voigt; Petersen, Jesper; Sørensen, Henrik; Dalgas, Ulrik

2018-01-01

To improve walking in persons with multiple sclerosis (MS), it is essential to understand the underlying mechanisms of walking. This study examined strategies in net joint power generated or absorbed by hip flexors, hip extensors, hip abductors, knee extensors, and plantar flexors in mildly disabled persons with MS and healthy controls at different walking speeds. Thirteen persons with MS and thirteen healthy controls participated and peak net joint power was calculated using 3D motion analysis. In general, no differences were found between speed-matched healthy controls and persons with MS, but the fastest walking speed was significantly higher in healthy controls (2.42 m/s vs. 1.70 m/s). The net joint power increased in hip flexors, hip extensors, hip abductors, knee extensors and plantar flexors in both groups, when walking speed increased. Significant correlations between changes in walking speed and changes in net joint power of plantar flexors, hip extensors and hip flexors existed in healthy controls and persons with MS, and in net knee extensor absorption power of persons with MS only. In contrast to previous studies, these findings suggest that mildly disabled persons with MS used similar kinetic strategies as healthy controls to increase walking speed.

An isokinetic training program for reducing falls in a community-dwelling older adult: a case report.

PubMed

Beebe, Justin A; Hines, Roger W; McDaniel, Laura T; Shelden, Brenda L

2013-01-01

With the population older than 65 years, projected to double by the year 2030, falls in older adults are a substantial health concern. Muscle strength deficits are one of the multifactorial components linked to increased fall risk, and decreasing these deficits has been one of the goals of interventions designed to decrease fall risk. These interventions have traditionally focused on improving peak torque; however, recent research suggests that exercise protocols that focus on the rate of torque development (RTD) may be more effective in decreasing fall risk. This case report examines clinical outcomes following implementation of an isokinetic strengthening protocol coupled with a balance program designed to reduce fall risk in a community-dwelling older adult. The individual was a 70-year-old woman with a history of 3 falls over the past 8 months and no related medical etiology who had self-limited her activities because of fear of another fall. She was classified as having substantial risk for future falls because of fall history, increased fear of falling, and below age norms on the Berg Balance Scale (BBS), and the Timed Up and Go (TUG). The treatment program consisted of 12 weeks of high-intensity isokinetic knee extensor training, high challenge dynamic gait and balance activities, and core strengthening. The isokinetic protocol consisted of 4 sets of 10 concentric-only repetitions at speeds of 240°/sec and 300°/sec for a total of 8 work sets. Dynamic gait activities incorporating directional and obstacle drills, and rocker and balance boards were used for balance training activities. Progressive theraband exercises were used for core strengthening. As her home program, the participant was encouraged to return to line dancing twice per week. During the 12-week protocol, the participant completed two 90-minute therapy sessions and two 90-minute dance classes per week. After the 12 weeks of treatment, knee extensor peak torque at 150 ms improved on the right from 67.8 N to 107.1 N (57.9% increase), and on the left from 65.1 N to 97.6 N (49.9% increase). The BBS score improved from 45 to 52; and the TUG improved from 14.0 to 8.6 seconds. Both final scores exceeded fall risk cutoffs (BBS = 48; TUG = 13.5 seconds) and the change score exceeded minimal detectable change (BBS = 7; TUG 5.4 seconds). The treatment program produced improvements in knee extensor peak torque and RTD, but more importantly, the final scores on the clinical outcome measures placed the participant above established fall-risk cutoff scores. Although future research with increased numbers of participants and a control group should be conducted to confirm this study's results, these findings support the use of isokinetic training to reduce fall risk in older adults.

Gait patterns and muscle activity in the lower extremities of elderly women during underwater treadmill walking against water flow.

PubMed

Shono, Tomoki; Masumoto, Kenji; Fujishima, Kazutaka; Hotta, Noboru; Ogaki, Tetsuro; Adachi, Takahiro

2007-11-01

This study sought to determine the characteristics of gait patterns and muscle activity in the lower extremities of elderly women during underwater treadmill walking against water flow. Eight female subjects (61.4+/-3.9 y) performed underwater and land treadmill walking at varying exercise intensities and velocities. During underwater walking (water level at the xiphoid process) using the Flowmill, which has a treadmill at the base of a water flume, the simultaneous belt and water flow velocities were set to 20, 30 and 4 m.min(-1). Land walking velocities were set to 40, 60 and 80 m.min(-1). Oxygen uptake and heart rate were measured during both walking exercises. Maximum and minimum knee joint angles, and mean angular velocities of knee extension and knee flexion in the swing phase were calculated using two-dimensional motion analysis. Electromyograms were recorded using bipolar surface electrodes for five muscles: the tibialis anterior (TA), medial gastrocnemius (MG), vastus medialis (VM), rectus femoris (RF) and biceps femoris (BF). At the same exercise intensity level, cadence was almost half that on land. Step length did not differ significantly because velocity was halved. Compared to land walking, the maximum and minimum knee joint angles were significantly smaller and the mean angular velocity of knee extension was significantly lower. Knee extension in the swing phase was limited by water resistance. While the muscle activity levels of TA, VM and BF were almost the same as during land walking, those of MG and RF were lower. At the same velocity, exercise intensity was significantly higher than during land walking, cadence was significantly lower, and step length significantly larger. The knee joint showed significantly smaller maximum and minimum angles, and the mean angular velocity of knee flexion was significantly larger. The muscle activity levels of TA, VM, and BF increased significantly in comparison with land walking, although those of MG and RF did not significantly differ. Given our findings, it appears that buoyancy, lower cadence, and a moving floor influenced the muscle activity level of MG and RF at the same exercise intensity level and at the same velocity. These results show promise of becoming the basic data of choice for underwater walking exercise prescription.

Crouch gait can be an effective form of forced-use/no constraint exercise for the paretic lower limb in stroke.

PubMed

Tesio, Luigi; Rota, Viviana; Malloggi, Chiara; Brugliera, Luigia; Catino, Luigi

2017-09-01

In hemiplegic gait the paretic lower limb provides less muscle power and shows a briefer stance compared with the unaffected limb. Yet, a longer stance and a higher power can be obtained from the paretic lower limb if gait speed is increased. This supports the existence of a 'learned non-use' phenomenon, similar to that underlying some asymmetric impairments of the motion of the eyes and of the upper limbs. Crouch gait (CG) (bent-hip bent-knee, about 30° minimum knee flexion) might be an effective form of 'forced-use' treatment of the paretic lower limb. It is not known whether it also stimulates a more symmetric muscle power output. Gait analysis on a force treadmill was carried out in 12 healthy adults and seven hemiplegic patients (1-127 months after stroke, median: 1.6). Speed was imposed at 0.3 m/s. Step length and single and double stance times, sagittal joint rotations, peak positive power, and work in extension of the hip, knee, and ankle (plantar flexion), and surface electromyography (sEMG) area from extensor muscles during the generation of power were measured on either side during both erect and crouch walking. Significance was set at P less than 0.05; corrections for multiplicity were applied. Patients, compared with healthy controls, adopted in both gait modalities and on both sides a shorter step length (61-84%) as well as a shorter stance (76-90%) and swing (63-83%) time. As a rule, they also provided a higher muscular work (median: 137%, range: 77-250%) paralleled by a greater sEMG area (median: 174%, range: 75-185%). In erect gait, the generation of peak extensor power across hip, knee, and ankle joints was in general lower (83-90%) from the paretic limb and higher (98-165%) from the unaffected limb compared with control values. In CG, peak power generation across the three lower limb joints was invariably higher in hemiparetic patients: 107-177% from the paretic limb and 114-231% from the unaffected limb. When gait shifted from erect to crouch, only for hemiplegic patients, at the hip, the paretic/unaffected ratio increased significantly. For peak power, work, sEMG area, and joint rotation, the paretic/unaffected ratio increased from 55 to 85%, 56 to 72%, 68 to 91%, and 67 to 93%, respectively. CG appears to be an effective form of forced-use exercise eliciting more power and work from the paretic lower limb muscles sustained by a greater neural drive. It also seems effective in forcing a more symmetric power and work from the hip extensor muscles, but neither from the knee nor the ankle.

Validity and reliability of an instrumented leg-extension machine for measuring isometric muscle strength of the knee extensors.

PubMed

Ruschel, Caroline; Haupenthal, Alessandro; Jacomel, Gabriel Fernandes; Fontana, Heiliane de Brito; Santos, Daniela Pacheco dos; Scoz, Robson Dias; Roesler, Helio

2015-05-20

Isometric muscle strength of knee extensors has been assessed for estimating performance, evaluating progress during physical training, and investigating the relationship between isometric and dynamic/functional performance. To assess the validity and reliability of an adapted leg-extension machine for measuring isometric knee extensor force. Validity (concurrent approach) and reliability (test and test-retest approach) study. University laboratory. 70 healthy men and women aged between 20 and 30 y (39 in the validity study and 31 in the reliability study). Intraclass correlation coefficient (ICC) values calculated for the maximum voluntary isometric torque of knee extensors at 30°, 60°, and 90°, measured with the prototype and with an isokinetic dynamometer (ICC2,1, validity study) and measured with the prototype in test and retest sessions, scheduled from 48 h to 72 h apart (ICC1,1, reliability study). In the validity analysis, the prototype showed good agreement for measurements at 30° (ICC2,1 = .75, SEM = 18.2 Nm) and excellent agreement for measurements at 60° (ICC2,1 = .93, SEM = 9.6 Nm) and at 90° (ICC2,1 = .94, SEM = 8.9 Nm). Regarding the reliability analysis, between-days' ICC1,1 were good to excellent, ranging from .88 to .93. Standard error of measurement and minimal detectable difference based on test-retest ranged from 11.7 Nm to 18.1 Nm and 32.5 Nm to 50.1 Nm, respectively, for the 3 analyzed knee angles. The analysis of validity and repeatability of the prototype for measuring isometric muscle strength has shown to be good or excellent, depending on the knee joint angle analyzed. The new instrument, which presents a relative low cost and easiness of transportation when compared with an isokinetic dynamometer, is valid and provides consistent data concerning isometric strength of knee extensors and, for this reason, can be used for practical, clinical, and research purposes.

Interactive effects of growth hormone and exercise on muscle mass in suspended rats

NASA Technical Reports Server (NTRS)

Grindeland, Richard E.; Roy, Roland R.; Edgerton, V. Reggie; Grossman, Elena J.; Mukku, Venkat R.; Jiang, Bian; Pierotti, David J.; Rudolph, Ingrid

1994-01-01

Measures to attenuate muscle atrophy in rats in response to simulated microgravity (hindlimb suspension (HS)) have been only partially successful. In the present study, hypophysectomized rats were in HS for 7 days, and the effects of recombinant human growth hormone (GH), exercise (Ex), or GH+Ex on the weights, protein concentrations, and fiber cross-sectional areas (CSAs) of hindlimb muscles were determined. The weights of four extensor muscles, i.e., the soleus (Sol), medial (MG) and lateral (LG) gastrocnemius, and plantaris (Plt), and one adductor, i.e., the adductor longus (AL), were decreased by 10-22% after HS. Fiber CSAs were decreased by 34% in the Sol and by 1 17% in the MG after HS. In contrast, two flexors, i.e., the tibialis anterior (TA) and extensor digitorum longus (EDL), did not atrophy. In HS rats, GH treatment alone maintained the weights of the fast extensors (MG, LG, Plt) and flexors (TA, EDL) at or above those of control rats. This effect was not observed in the slow extensor (Sol) or AL. Exercise had no significant effect on the weight of any muscle in HS rats. A combination of GH and Ex treatments yielded a significant increase in the weights of the fast extensors and in the CSA of both fast and slow fibers of the MG and significantly increased Sol weight and CSA of the slow fibers of the Sol. The AL was not responsive to either GH or Ex treatments. Protein concentrations of the Sol and MG were higher only in the Sol of Ex and GH+Ex rats. These results suggest that while GH treatment or intermittent high intensity exercise alone have a minimal effect in maintaining the mass of unloaded muscle, there is a strong interactive effect of these two treatments.

Creatine supplementation during pulmonary rehabilitation in chronic obstructive pulmonary disease.

PubMed

Fuld, J P; Kilduff, L P; Neder, J A; Pitsiladis, Y; Lean, M E J; Ward, S A; Cotton, M M

2005-07-01

Skeletal muscle wasting and dysfunction are strong independent predictors of mortality in patients with chronic obstructive pulmonary disease (COPD). Creatine nutritional supplementation produces increased muscle mass and exercise performance in health. A controlled study was performed to look for similar effects in 38 patients with COPD. Thirty eight patients with COPD (mean (SD) forced expiratory volume in 1 second (FEV(1)) 46 (15)% predicted) were randomised to receive placebo (glucose polymer 40.7 g) or creatine (creatine monohydrate 5.7 g, glucose 35 g) supplements in a double blind trial. After 2 weeks loading (one dose three times daily), patients participated in an outpatient pulmonary rehabilitation programme combined with maintenance (once daily) supplementation. Pulmonary function, body composition, and exercise performance (peripheral muscle strength and endurance, shuttle walking, cycle ergometry) took place at baseline (n = 38), post loading (n = 36), and post rehabilitation (n = 25). No difference was found in whole body exercise performance between the groups: for example, incremental shuttle walk distance mean -23.1 m (95% CI -71.7 to 25.5) post loading and -21.5 m (95% CI -90.6 to 47.7) post rehabilitation. Creatine increased fat-free mass by 1.09 kg (95% CI 0.43 to 1.74) post loading and 1.62 kg (95% CI 0.47 to 2.77) post rehabilitation. Peripheral muscle performance improved: knee extensor strength 4.2 N.m (95% CI 1.4 to 7.1) and endurance 411.1 J (95% CI 129.9 to 692.4) post loading, knee extensor strength 7.3 N.m (95% CI 0.69 to 13.92) and endurance 854.3 J (95% CI 131.3 to 1577.4) post rehabilitation. Creatine improved health status between baseline and post rehabilitation (St George's Respiratory Questionnaire total score -7.7 (95% CI -14.9 to -0.5)). Creatine supplementation led to increases in fat-free mass, peripheral muscle strength and endurance, health status, but not exercise capacity. Creatine may constitute a new ergogenic treatment in COPD.

Effects of once weekly NMES training on knee extensors fatigue and body composition in a person with spinal cord injury.

PubMed

Gorgey, Ashraf S; Caudill, Caelb; Khalil, Refka E

2016-01-01

Single-subject case (male, 33 years of age, T6 SCI AIS A). To determine the effect of surface neuromuscular electrical stimulation (NMES) training conducted once weekly on improving fatigue resistance as well as regional and whole body composition in an individual with spinal cord injury (SCI). Laboratory setting within a SCI Center. Surface NMES resistance training (RT) of the paralyzed knee extensors was conducted once weekly for 12 weeks using ankle weights. Knee extensor fatigue index was determined by the number of repetitions (reps) achieved out of 30 reps. Total and regional body composition including percentage body fat (%BF), fat mass (FM), lean mass (LM) were conducted before the first session and one week after the last training session using whole-body dual-energy X-ray absorptiometry. The participant had a compliance rate of 83% and he was able to lift 6 and 2 lbs on the right and left legs, respectively. Right knee extensors showed greater fatigue resistance compared to the left one. Leg LM increased by 6% accompanied with decrease in arm, trunk and total body LM by -4.7%, -13%, -5%, respectively. The %BF increased by 8%, 7.3%, 15.5%, 11.5% for arm, legs, trunk and total body. Once weekly of NMES RT evokes local positive changes in leg LM without reciprocating the continuous loss in LM or gain in FM in other regions and total body. Training was effective in increasing strength as well as fatigue resistance of the trained knee extensors.

ASSOCIATION OF KNEE PAIN WITH A REDUCTION IN THIGH MUSCLE STRENGTH – A CROSS-SECTIONAL ANALYSIS INCLUDING 4553 OSTEOARTHRITIS INITIATIVE PARTICIPANTS

PubMed Central

Ruhdorfer, Anja; Wirth, Wolfgang; Eckstein, Felix

2016-01-01

Objective To cross-sectionally determine the quantitative relationship of age-adjusted, sex-specific isometric knee extensor and flexor strength to patient-reported knee pain. Methods Difference of thigh muscle strength by age, and that of age-adjusted strength per unit increase on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) knee pain scale, was estimated from linear regression analysis of 4553 Osteoarthritis Initiative participants (58% women). Strata encompassing the minimal clinically important difference (MCID) in knee pain were compared to evaluate a potentially non-linear relationship between WOMAC pain levels and muscle strength. Results In Osteoarthritis Initiative participants without pain, the age-related difference in isometric knee extensor strength was −9.0%/−8.2% (women/men) per decade, and that of flexor strength was −11%/−6.9%. Differences in age-adjusted strength values for each unit of WOMAC pain (1/20) amounted to −1.9%/−1.6% for extensor and −2.5%/−1.7% for flexor strength. Differences in torque/weight for each unit of WOMAC pain ranged from −3.3 to − 2.1%. There was no indication of a non-linear relationship between pain and strength across the range of observed WOMAC values, and similar results were observed in women and men. Conclusion Each increase by 1/20 units in WOMAC pain was associated with a ~2% lower age-adjusted isometric extensor and flexor strength in either sex. As a reduction in muscle strength is known to prospectively increase symptoms in knee osteoarthritis and as pain appears to reduce thigh muscle strength, adequate therapy of pain and muscle strength is required in knee osteoarthritis patients to avoid a vicious circle of self-sustaining clinical deterioration. PMID:27836675

Effects of whole-body cryotherapy (-110 °C) on proprioception and indices of muscle damage.

PubMed

Costello, J T; Algar, L A; Donnelly, A E

2012-04-01

The purpose of this study was to investigate the effects of whole-body cryotherapy (WBC) on proprioceptive function, muscle force recovery following eccentric muscle contractions and tympanic temperature (T(TY) ). Thirty-six subjects were randomly assigned to a group receiving two 3-min treatments of -110 ± 3 °C or 15 ± 3 °C. Knee joint position sense (JPS), maximal voluntary isometric contraction (MVIC) of the knee extensors, force proprioception and T(TY) were recorded before, immediately after the exposure and again 15 min later. A convenience sample of 18 subjects also underwent an eccentric exercise protocol on their contralateral left leg 24 h before exposure. MVIC (left knee), peak power output (PPO) during a repeated sprint on a cycle ergometer and muscles soreness were measured pre-, 24, 48 and 72h post-treatment. WBC reduced T(TY) , by 0.3 °C, when compared with the control group (P<0.001). However, JPS, MVIC or force proprioception was not affected. Similarly, WBC did not effect MVIC, PPO or muscle soreness following eccentric exercise. WBC, administered 24 h after eccentric exercise, is ineffective in alleviating muscle soreness or enhancing muscle force recovery. The results of this study also indicate no increased risk of proprioceptive-related injury following WBC. © 2011 John Wiley & Sons A/S.

Selective contribution of each hamstring muscle to anterior cruciate ligament protection and tibiofemoral joint stability in leg-extension exercise: a simulation study.

PubMed

Biscarini, Andrea; Botti, Fabio Massimo; Pettorossi, Vito Enrico

2013-09-01

A biomechanical model was developed to simulate the selective effect of the co-contraction force provided by each hamstring muscle on the shear and compressive tibiofemoral joint reaction forces, during open kinetic-chain knee-extension exercises. This model accounts for instantaneous values of knee flexion angle [Formula: see text], angular velocity and acceleration, and for changes in magnitude, orientation, and application point of external resistance. The tibiofemoral shear force (TFSF) largely determines the tensile force on anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). Biceps femoris is the most effective hamstring muscle in decreasing the ACL-loading TFSF developed by quadriceps contractions for [Formula: see text]. In this range, the semimembranosus generates the dominant tibiofemoral compressive force, which enhances joint stability, opposes anterior/posterior tibial translations, and protects cruciate ligaments. The semitendinosus force provides the greatest decreasing gradient of ACL-loading TFSF for [Formula: see text], and the greatest increasing gradient of tibiofemoral compressive force for [Formula: see text]. However, semitendinosus efficacy is strongly limited by its small physiological section. Hamstring muscles behave as a unique muscle in enhancing the PCL-loading TFSF produced by quadriceps contractions for [Formula: see text]. The levels of hamstrings co-activation that suppress the ACL-loading TFSF considerably shift when the knee angular acceleration is changed while maintaining the same level of knee extensor torque by a concurrent adjustment in the magnitude of external resistance. The knowledge of the specific role and the optimal activation level of each hamstring muscle in ACL protection and tibiofemoral stability are fundamental for planning safe and effective rehabilitative knee-extension exercises.

Noninvasive lifting of arm, thigh, and knee skin with transcutaneous intense focused ultrasound.

PubMed

Alster, Tina S; Tanzi, Elizabeth L

2012-05-01

Transcutaneous intense focused ultrasound is a novel Food and Drug Administration-approved technology for noninvasive skin tightening of the face and neck. No studies have reported on its safety and effectiveness on nonfacial areas. Eighteen paired areas (6 each) on the upper arms, medial thighs, and extensor knees were randomly treated with two different transducers (4.0 MHz, 4.5-mm focal depth and 7.0 MHz, 3.0-mm focal depth). One side was randomly assigned to receive a single pass (single plane) of microthermal coagulation zones over the involved area with the 4.0 MHz, 4.5-mm-depth transducer, and the contralateral side was assigned to receive consecutive single passes (dual plane) using both transducers (4.0 MHz, 4.5-mm depth followed by 7.0 MHz, 3.0-mm depth). Two independent masked assessors determined clinical improvement scores using comparative standardized photographs obtained at baseline and 3 and 6 months after treatment. Subjective assessments of clinical improvement and side effects of treatment were obtained. Global assessment scores revealed significant improvement in all treated areas, with the upper arms and knees demonstrating more skin lifting and tightening than the thighs. Areas receiving dual-plane treatment had slightly better clinical scores than those receiving single-plane treatment in all three sites. Clinical scores from single-plane and dual-plane treated areas continued to improve between 3 and 6 months after treatment. Side effects were mild and transient and included erythema, warmth, and skin tenderness. Rare focal bruising was noted in two patients on the upper arms that resolved within 7 days. No other side effects were reported or observed. Transcutaneous intense focused ultrasound can be safely and effectively used to improve the clinical appearance (texture and contour) of the upper arms, extensor knees, and medial thighs. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

Relation between isokinetic muscle strength and functional capacity in recreational athletes with chondromalacia patellae

PubMed Central

Yildiz, Y; Aydin, T; Sekir, U; Cetin, C; Ors, F; Alp, K

2003-01-01

Objectives: To investigate the effects of isokinetic exercise on pain and functional test scores of recreational athletes with chondromalacia patellae (CMP) and to examine the correlation between isokinetic parameters and functional tests or pain score. Methods: The functional ability of 30 recreational athletes with unilateral CMP was evaluated using six different tests. Pain scores were assessed during daily activities before and after the treatment protocol. Isokinetic exercise sessions were carried out at angular velocities of 60°/s (25–90° range of flexion) and 180°/s (full range). These sessions were repeated three times a week for six weeks. Results: Quadriceps and hamstring peak torque, total work, and endurance ratios had improved significantly after the treatment, as did the functional parameters and pain scores. There was a poor correlation between the extensor endurance ratio and one leg standing test. A moderate correlation between the visual analogue scale and the extensor endurance ratio or flexion endurance ratio was also found. Conclusions: The isokinetic exercise programme used in this study had a positive effect on muscle strength, pain score, and functional ability of knees with CMP. The improvement in the functional capacity did not correlate with the isokinetic parameters. PMID:14665581

Low-frequency electric muscle stimulation combined with physical therapy after total hip arthroplasty for hip osteoarthritis in elderly patients: a randomized controlled trial.

PubMed

Gremeaux, Vincent; Renault, Julien; Pardon, Laurent; Deley, Gaelle; Lepers, Romuald; Casillas, Jean-Marie

2008-12-01

To assess the effects of low-frequency electric muscle stimulation associated with usual physiotherapy on functional outcome after total hip arthroplasty (THA) for hip osteoarthritis (OA) in elderly subjects. Randomized controlled trial; pre- and posttreatment measurements. Hospital rehabilitation department. Subjects (N=29) referred to the rehabilitation department after THA for hip OA. The intervention group (n=16; 78+/-8 y) received simultaneous low-frequency electric muscle stimulation of bilateral quadriceps and calf muscles (highest tolerated intensity, 1h session, 5 d/wk, for 5 weeks) associated with conventional physical therapy including resistance training. The control group (n=13; 76+/-10 y) received conventional physical therapy alone (25 sessions). Maximal isometric strength of knee extensors, FIM instrument, before and after; a six-minute walk test and a 200 m fast walk test, after; length of stay (LOS). Low-frequency electric muscle stimulation was well tolerated. It resulted in a greater improvement in strength of knee extensors on the operated side (77% vs 23%; P<.01), leading to a better balance of muscle strength between the operated and nonoperated limb. The low-frequency electric muscle stimulation group also showed a greater improvement in FIM scores, though improvements in the walk tests were similar for the 2 groups, as was LOS. Low-frequency electric muscle stimulation is a safe, well-tolerated therapy after THA for hip OA. It improves knee extensor strength, which is one of the factors leading to greater functional independence after THA.

The impact of type 1 diabetes and diabetic polyneuropathy on muscle strength and fatigability.

PubMed

Orlando, Giorgio; Balducci, Stefano; Bazzucchi, Ilenia; Pugliese, Giuseppe; Sacchetti, Massimo

2017-06-01

Although it is widely accepted that diabetic polyneuropathy (DPN) is linked to a marked decline in neuromuscular performance, information on the possible impact of type 1 diabetes (T1D) on muscle strength and fatigue remains unclear. The purpose of this study was to investigate the effects of T1D and DPN on strength and fatigability in knee extensor muscles. Thirty-one T1D patients (T1D), 22 T1D patients with DPN (DPN) and 23 matched healthy control participants (C) were enrolled. Maximal voluntary contraction (MVC) and endurance time at an intensity level of 50% of the MVC were assessed at the knee extensor muscles with an isometric dynamometer. Clinical characteristics of diabetic patients were assessed by considering a wide range of vascular and neurological parameters. DPN group had lower knee extensor muscles strength than T1D (-19%) and the C group (-37.5%). T1D group was 22% weaker when compared to the C group. Lower body muscle fatigability of DPN group was 22 and 45.5% higher than T1D and C group, respectively. T1D group possessed a higher fatigability (29.4%) compared to C group. A correlation was found between motor and sensory nerve conduction velocity and muscle strength and fatigability. Patients with T1D are characterised by both a higher fatigability and a lower muscle strength, which are aggravated by DPN. Our data suggest that factors other than nervous damage play a role in the pathogenesis of such defect.

Associations of knee muscle force, bone malalignment, and knee-joint laxity with osteoarthritis in elderly people.

PubMed

Nakagawa, Kazumasa; Maeda, Misako

2017-03-01

[Purpose] From the viewpoint of prevention of knee osteoarthritis, the aim of this study was to verify how muscle strength and joint laxity are related to knee osteoarthritis. [Subjects and Methods] The study subjects consisted of 90 community-dwelling elderly people aged more than 60 years (22 males, 68 females). Femorotibial angle alignment, knee joint laxity, knee extensors and flexor muscle strengths were measured in all subjects. In addition, the subjects were divided into four groups based on the presence of laxity and knee joint deformation, and the muscle strength values were compared. [Results] There was no significant difference in knee extensor muscle strength among the four groups. However, there was significant weakness of the knee flexor muscle in the group with deformation and laxity was compared with the group without deformation and laxity. [Conclusion] Decreased knee flexor muscle strengths may be involved in knee joint deformation. The importance of muscle strength balance was also considered.

Fracture of the proximal tibia after revision total knee arthroplasty with an extensor mechanism allograft.

PubMed

Klein, Gregg R; Levine, Harlan B; Sporer, Scott M; Hartzband, Mark A

2013-02-01

Extensor mechanism reconstruction with an extensor mechanism allograft (EMA) remains one of the most reliable methods for treating the extensor mechanism deficient total knee arthroplasty. We report 3 patients who were treated with an EMA who sustained a proximal tibial shaft fracture. In all 3 cases, a short tibial component was present that ended close to the level of the distal extent of the bone block. When performing an EMA, it is important to recognize that the tibial bone block creates a stress riser and revision to a long-stemmed tibial component should be strongly considered to bypass this point to minimize the risk of fracture. Copyright © 2013 Elsevier Inc. All rights reserved.

Recovery after high-intensity intermittent exercise in elite soccer players using VEINOPLUS sport technology for blood-flow stimulation.

PubMed

Bieuzen, François; Pournot, Hervé; Roulland, Rémy; Hausswirth, Christophe

2012-01-01

Electric muscle stimulation has been suggested to enhance recovery after exhaustive exercise by inducing an increase in blood flow to the stimulated area. Previous studies have failed to support this hypothesis. We hypothesized that the lack of effect shown in previous studies could be attributed to the technique or device used. To investigate the effectiveness of a recovery intervention using an electric blood-flow stimulator on anaerobic performance and muscle damage in professional soccer players after intermittent, exhaustive exercise. Randomized controlled clinical trial. National Institute of Sport, Expertise, and Performance (INSEP). Twenty-six healthy professional male soccer players. The athletes performed an intermittent fatiguing exercise followed by a 1-hour recovery period, either passive or using an electric blood-flow stimulator (VEINOPLUS). Participants were randomly assigned to a group before the experiment started. Performances during a 30-second all-out exercise test, maximal vertical countermovement jump, and maximal voluntary contraction of the knee extensor muscles were measured at rest, immediately after the exercise, and 1 hour and 24 hours later. Muscle enzymes indicating muscle damage (creatine kinase, lactate dehydrogenase) and hematologic profiles were analyzed before and 1 hour and 24 hours after the intermittent fatigue exercise. The electric-stimulation group had better 30-second all-out performances at 1 hour after exercise (P = .03) in comparison with the passive-recovery group. However, no differences were observed in muscle damage markers, maximal vertical countermovement jump, or maximal voluntary contraction between groups (P > .05). Compared with passive recovery, electric stimulation using this blood-flow stimulator improved anaerobic performance at 1 hour postintervention. No changes in muscle damage markers or maximal voluntary contraction were detected. These responses may be considered beneficial for athletes engaged in sports with successive rounds interspersed with short, passive recovery periods.

Intrarater reliability of the Humac NORM isokinetic dynamometer for strength measurements of the knee and shoulder muscles.

PubMed

Habets, Bas; Staal, J Bart; Tijssen, Marsha; van Cingel, Robert

2018-01-10

To determine the intrarater reliability of the Humac NORM isokinetic dynamometer for concentric and eccentric strength tests of knee and shoulder muscles. 54 participants (50% female, average age 20.9 ± 3.1 years) performed concentric and eccentric strength measures of the knee extensors and flexors, and the shoulder internal and external rotators on two different Humac NORM isokinetic dynamometers, which were situated at two different centers. The knee extensors and flexors were tested concentrically at 60° and 180°/s, and eccentrically at 60° s. Concentric strength of the shoulder internal and external rotators, and eccentric strength of the external rotators were measured at 60° and 120°/s. We calculated intraclass correlation coefficients (ICCs), standard error of measurement, standard error of measurement expressed as a %, and the smallest detectable change to determine reliability and measurement error. ICCs for the knee tests ranged from 0.74 to 0.89, whereas ICC values for the shoulder tests ranged from 0.72 to 0.94. Measurement error was highest for the concentric test of the knee extensors and lowest for the concentric test of shoulder external rotators.

Poor correlation between handgrip strength and isokinetic performance of knee flexor and extensor muscles in community-dwelling elderly women.

PubMed

Felicio, Diogo Carvalho; Pereira, Daniele Sirineu; Assumpção, Alexandra Miranda; de Jesus-Moraleida, Fabianna Resende; de Queiroz, Barbara Zille; da Silva, Juscelio Pereira; de Brito Rosa, Naysa Maciel; Dias, João Marcos Domingues; Pereira, Leani Souza Máximo

2014-01-01

To investigate the correlation between handgrip strength and performance of knee flexor and extensor muscles determined using an isokinetic dynamometer in community-dwelling elderly women. This was a cross-sectional study. Sample selection for the study was made by convenience, and 221 (71.07 ± 4.93 years) community-dwelling elderly women were included. Knee flexor and extensor muscle performance was measured using an isokinetic dynamometer Biodex System 3 Pro. The isokinetic variables chosen for analysis were peak torque, peak torque/bodyweight, total work/bodyweight, total work, average power, and agonist/antagonist ratio at the angular velocities of 60°/s and 180°/s. Assessment of handgrip strength was carried out using the Jamar dynamometer. Spearman's correlation coefficient was calculated to identify intervariable correlations. Only knee flexor peak torque (60°/s) and average power (60°/s), and knee extensor peak torque (180°/s) and total work (180°/s) were significantly (P < 0.05), yet poorly, correlated with handgrip strength (r < 0.30). The majority of analyses did not show any correlation between variables assessed by isokinetic dynamometer and handgrip dynamometer. Caution is required when generalizing handgrip strength as a predictor of global muscle strength in community-dwelling elderly women. © 2013 Japan Geriatrics Society.

Sagittal-Plane Knee Moment During Gait and Knee Cartilage Thickness.

PubMed

Schmitz, Randy J; Harrison, David; Wang, Hsin-Min; Shultz, Sandra J

2017-06-02

  Understanding the factors associated with thicker cartilage in a healthy population is important when developing strategies aimed at minimizing the cartilage thinning associated with knee osteoarthritis progression. Thicker articular cartilage is commonly thought to be healthier cartilage, but whether the sagittal-plane biomechanics important to gait are related to cartilage thickness is unknown.   To determine the relationship of a weight-bearing region of the medial femoral condyle's cartilage thickness to sagittal gait biomechanics in healthy individuals.   Descriptive laboratory study.   Laboratory.   Twenty-eight healthy participants (15 women: age = 21.1 ± 2.1 years, height = 1.63 ± 0.07 m, weight = 64.6 ± 9.9 kg; 13 men: age = 22.1 ± 2.9 years, height = 1.79 ± 0.05 m, weight = 75.2 ± 9.6 kg).   Tibiofemoral angle (°) was obtained via goniometric assessment, thickness of the medial femoral condyle cartilage (mm) was obtained via ultrasound imaging, and peak internal knee-extensor moment (% body weight · height) was measured during 10 trials of over-ground walking at a self-selected pace. We used linear regression to examine the extent to which peak internal knee-extensor moment predicted cartilage thickness after accounting for tibiofemoral angle and sex.   Sex and tibiofemoral angle (12.3° ± 3.2°) were entered in the initial step as control factors (R 2 = 0.01, P = .872). In the final step, internal knee-extensor moment (1.5% ± 1.3% body weight · height) was entered, which resulted in greater knee-extensor moment being related to greater cartilage thickness (2.0 ± 0.3 mm; R 2 Δ = 0.31, PΔ = .003).   Individuals who walked with a greater peak internal knee-extensor moment during gait had a cartilage structure that is generally considered beneficial in a healthy population. Our study offers promising findings that a potentially modifiable biomechanical factor is associated with cartilage status in a healthy population. Establishing these baseline relationships in uninjured populations may help us to better understand potential factors related to maladaptive gait patterns that predispose a person to adverse changes in the cartilage environment.

Muscular control of a learned movement: the speed control system hypothesis.

PubMed

Enoka, R M

1983-01-01

The "speed control system" hypothesis, which represents an attempt to identify an invariant characteristic of learned movements, postulates that movements of variable extent are controlled by regulating the intensity of muscle contractions such that the contraction duration remains constant. The contingency set originally utilized to develop this hypothesis was expanded by examining a movement that was multidirectional and multiarticular, and executed by large muscle groups generating near maximum torques. The investigation focused on the techniques utilized by weightlifters to control lower extremity displacement during the initial phase of the double knee bend execution of the "clean" in Olympic weightlifting. The combination of the quantified muscle activity and the angular velocity, both about the knee joint, revealed a sequence of shortening-lengthening muscle contractions throughout the movement. The first two periods of net muscular activity, one extensor and the other flexor, were utilized to examine the movement for invariant characteristics. As predicted by the speed control system hypothesis, the duration of the first period of net muscle torque activity (extensor) did not vary significantly, for either group of subjects, over the relative loads examined. The duration of the second period of activity (resultant flexor muscle torque), however, was not constant across loads, and further, the direction of the change depended upon the level of expertise. The more capable lifters tended to increase the duration of the resultant flexor involvement while the less skilled athletes utilized the reverse strategy when the load was increased. Conversely, the intensity of the muscle activity for both groups of subjects and both the extensor and flexor periods covaried with load, as predicted by the hypothesis. The speed control system hypothesis, therefore, provided an appropriate explanation for the first component of the movement, the period of extensor dominated (shortening contraction) muscle torque, but was inappropriate for the subsequent interval, a resultant flexor (largely lengthening contraction) muscle torque.

A robotic exoskeleton to treat crouch gait from cerebral palsy: Initial kinematic and neuromuscular evaluation.

PubMed

Lerner, Zachary F; Damiano, Diane L; Bulea, Thomas C

2016-08-01

A robotic exoskeleton was designed for individuals with crouch gait caused by cerebral palsy with the intent to supplement existing muscle function during walking. The aim of this study was to evaluate how powered knee extension assistance provided during stance and swing phases of the gait cycle affect knee kinematics, and knee flexor and extensor muscle activity. Muscle activity and kinematic data were collected from four individuals with crouch gait from cerebral palsy during their normal walking condition and while walking with the exoskeleton under stance, swing, and stance & swing assistance. The exoskeleton was effective in reducing crouch by an average of 13.8° in three of the four participants when assistance was provided during the stance phase; assistance during the swing phase alone was ineffective. Peak knee extensor activity was maintained for all of the conditions during the stance and swing phases. Integrated (i.e. area under the curve) knee extensor activity decreased in two of the subjects indicating a more well-modulated activation pattern. Modest increases in peak and integrated antagonist knee flexor activity were exhibited in all participants; the subject without kinematic improvement had the greatest increase. While the exoskeleton was well tolerated, additional training with a focus on reducing knee flexor activity may lead to further improvements in crouch gait reduction.

Measurement of maximal isometric torque and muscle quality of the knee extensors and flexors in healthy 50- to 70-year-old women.

PubMed

Francis, Peter; Toomey, Clodagh; Mc Cormack, William; Lyons, Mark; Jakeman, Philip

2017-07-01

Muscle quality is defined as strength per unit muscle mass. The aim of this study was to measure the maximal voluntary isometric torque of the knee extensor and flexor muscle groups in healthy older women and to develop an index of muscle quality based on the combined knee extensor and flexor torque per unit lean tissue mass (LTM) of the upper leg. One hundred and thirty-six healthy 50- to 70-year-old women completed an initial measurement of isometric peak torque of the knee extensors and flexors (Con-Trex MJ; CMV AG, Dubendorf, Switzerland) that was repeated 7 days later. Subsequently, 131 women returned for whole- and regional-body composition analysis (iDXA ™ ; GE Healthcare, Chalfont St Giles, Buckinghamshire, UK). Isometric peak torque demonstrated excellent within-assessment reliability for both the knee extensors and flexors (ICC range: 0·991-1·000). Test-retest reliability was lower (ICC range: 0·777-0·828) with an observed mean increase of 5% in peak torque [6·2 (17·2) N m] on the second day of assessment (P<0·001). The relative mean decrease in combined isometric peak torque (-12·2%; P = 0·001) was double that of the relative, non-significant, median difference in upper leg LTM (-5·3%; P = 0·102) between those in the 5th and 6th decade. The majority of difference in peak isometric torque came from the knee extensors (15·1 N m, P<0·001 versus 2·4 N m, P = 0·234). Isometric peak torque normalized for upper leg LTM (muscle quality) was 8% lower between decades (P = 0·029). These findings suggest strength per unit tissue may provide a better indication of age-related differences in muscle quality prior to change in LTM. © 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Myocellular enzyme leakage, polymorphonuclear neutrophil activation and delayed onset muscle soreness induced by isokinetic eccentric exercise.

PubMed

Croisier, J L; Camus, G; Deby-Dupont, G; Bertrand, F; Lhermerout, C; Crielaard, J M; Juchmès-Ferir, A; Deby, C; Albert, A; Lamy, M

1996-01-01

To address the question of whether delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of the arachidonic acid derived product prostaglandin E2 (PGE2). 10 healthy male subjects were submitted to eccentric and concentric isokinetic exercises on a Kin Trex device at 60 degrees/s angular velocity. Exercise consisted of 8 stages of 5 maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases. There was an interval of at least 30 days between eccentric and concentric testing, and the order of the two exercise sessions was randomly assigned. The subjective presence and intensity of DOMS was evaluated using a visual analogue scale, immediately, following 24 h and 48 h after each test. Five blood samples were drawn from an antecubital vein: at rest before exercise, immediately after, after 30 min recovery, 24 h and 48 h after the tests. The magnitude of the acute inflammatory response to exercise was assessed by measuring plasma levels of polymorphonuclear elastase ([EL]), myeloperoxidase ([MPO]) and PGE2 ([PGE2]). Using two way analysis of variance, it appeared that only eccentric exercise significantly increased [EL] and DOMS, especially of the hamstring muscles. Furthermore, a significant decrease in eccentric peak torque of this muscle group only was observed on day 2 after eccentric work (- 21%; P < 0.002). Serum activity of creatine kinase and serum concentration of myoglobin increased significantly 24 and 48 h after both exercise tests. However, these variables reached significantly higher values following eccentric contractions 48 h after exercise. Mean [PGE2] in the two exercise modes remained unchanged over time and were practically equal at each time point. On the basis of these findings, we conclude that the magnitude of polymorphonuclear (PMN) activation, muscle damage, and DOMS are greater after eccentric than after concentric muscle contractions. However, the hypothesized interplay between muscle damage, increased PGE2 production, DOMS sensations, and reduced isokinetic muscle performance was not substantiated by the present results.

Vitamin D status and physical function in older Finnish people: A one-year follow-up study.

PubMed

Salminen, Marika; Saaristo, Pilvi; Salonoja, Maritta; Vaapio, Sari; Vahlberg, Tero; Lamberg-Allardt, Christel; Aarnio, Pertti; Kivelä, Sirkka-Liisa

2015-01-01

The aim was to describe vitamin D status and its association with changes in PF during 12 months in Finnish community-dwelling elderly (≥65 years). Baseline serum 25-hydroxyvitamin D (25OHD) concentration was measured by enzymeimmunoassay, and participants (n=518) were divided according to 25OHD to three groups (I <50 nmol/l, II 50-74.9 nmol/l, and III ≥75 nmol/l). PF (maximal isometric extension strength of right and left knee, and time in five-repetition sit-to-stand test (5STS) and 10-m walking test) was measured at baseline and after 12 months. 25OHD deficiency (<50 nmol/l) was found in 20.5% of the participants. During a 12-month follow-up, differences in changes in knee extensor strength of right (p=0.044) and left (p=0.010) lower extremity and in 10-m walking test (p=.040) between the groups were significant. According to further pairwise comparisons these differences were between groups I and III (right knee, p=0.036; left knee, p=0.009; 10-m walk, p=0.044), with the exception of left knee extensor strength in which there were also significant difference between groups I and II (p=0.039). All significant differences in changes were in favour of group II or III. Significant differences in changes in knee extensor strengths maintained after adjustments for group (intervention/control), parathyroid hormone, and baseline level of knee extensor strength. Prospective analyses showed low 25OHD concentrations (<50 nmol/l) to be associated with deterioration in PF during 12 months compared with high 25OHD concentrations (≥75 nmol/l). Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Muscle function in aged women in response to a water-based exercises program and progressive resistance training.

PubMed

Bento, Paulo Cesar Barauce; Rodacki, André Luiz Felix

2015-11-01

The purpose of the present study was to determine the effects of a water-based exercise program on muscle function compared with regular high-intensity resistance training. Older women (n = 87) were recruited from the local community. The inclusion criteria were, to be aged 60 years or older, able to walk and able to carry out daily living activities independently. Participants were randomly assigned to one of the following groups: water-based exercises (WBG), resistance training (RTG) or control (CG). The experimental groups carried out 12 weeks of an excise program performed on water or on land. The dynamic strength, the isometric peak, and rate of torque development for the lower limbs were assessed before and after interventions. The water-based program provided a similar improvement in dynamic strength in comparison with resistance training. The isometric peak torque increased around the hip and ankle joints in the water-based group, and around the knee joint in the resistance-training group (P < 0.05). The rate of torque development increased only in the water-based group around the hip extensors muscles (P < 0.05). Water-based programs constitute an attractive alternative to promote relevant strength gains using moderate loads and fast speed movements, which were also effective to improve the capacity to generate fast torques. © 2014 Japan Geriatrics Society.

Influence of Skeletal Muscle Carnosine Content on Fatigue during Repeated Resistance Exercise in Recreationally Active Women

PubMed Central

Varanoske, Alyssa N.; Hoffman, Jay R.; Church, David D.; Baker, Kayla M.; Dodd, Sarah J.; Coker, Nicholas A.; Oliveira, Leonardo P.; Dawson, Virgil L.; Stout, Jeffrey R.

2017-01-01

Carnosine is a naturally occurring intramuscular dipeptide that is thought to attenuate fatigue during high-intensity exercise. Carnosine content is influenced by various factors, including gender and diet. Despite research reporting that carnosine content is lower in women compared to men and lower in vegetarians compared to omnivores, no investigations have examined carnosine content in women based on dietary protein intake and its effect on muscle fatigue. Twenty recreationally active women were assigned to either a high (HI; n = 5), moderate (MOD; n = 10), or low (LO; n = 5) group based upon intramuscular carnosine content of the vastus lateralis. Each participant underwent two unilateral maximal voluntary isometric contractions (MVIC) of the knee extensors separated by an isokinetic exercise protocol consisting of five sets of 50 repeated maximal unilateral contractions. Magnitude-based inferences were used to analyze group differences. Percent decline in rate of force development and peak torque (PT) during the MVICs and changes in PT and mean torque during the muscle-fatiguing protocol were lower in HI compared to both MOD and LO. Additionally, absolute and relative dietary protein intake were greater in HI compared to MOD or LO. Results indicated that greater intramuscular carnosine content was reflective of greater dietary protein intake and that individuals with higher carnosine content displayed a greater attenuation of fatigue compared to those with lower carnosine. PMID:28880219

Influence of Skeletal Muscle Carnosine Content on Fatigue during Repeated Resistance Exercise in Recreationally Active Women.

PubMed

Varanoske, Alyssa N; Hoffman, Jay R; Church, David D; Wang, Ran; Baker, Kayla M; Dodd, Sarah J; Coker, Nicholas A; Oliveira, Leonardo P; Dawson, Virgil L; Fukuda, David H; Stout, Jeffrey R

2017-09-07

Carnosine is a naturally occurring intramuscular dipeptide that is thought to attenuate fatigue during high-intensity exercise. Carnosine content is influenced by various factors, including gender and diet. Despite research reporting that carnosine content is lower in women compared to men and lower in vegetarians compared to omnivores, no investigations have examined carnosine content in women based on dietary protein intake and its effect on muscle fatigue. Twenty recreationally active women were assigned to either a high (HI; n = 5), moderate (MOD; n = 10), or low (LO; n = 5) group based upon intramuscular carnosine content of the vastus lateralis. Each participant underwent two unilateral maximal voluntary isometric contractions (MVIC) of the knee extensors separated by an isokinetic exercise protocol consisting of five sets of 50 repeated maximal unilateral contractions. Magnitude-based inferences were used to analyze group differences. Percent decline in rate of force development and peak torque (PT) during the MVICs and changes in PT and mean torque during the muscle-fatiguing protocol were lower in HI compared to both MOD and LO. Additionally, absolute and relative dietary protein intake were greater in HI compared to MOD or LO. Results indicated that greater intramuscular carnosine content was reflective of greater dietary protein intake and that individuals with higher carnosine content displayed a greater attenuation of fatigue compared to those with lower carnosine.

Muscle mechanical advantage of human walking and running: implications for energy cost.

PubMed

Biewener, Andrew A; Farley, Claire T; Roberts, Thomas J; Temaner, Marco

2004-12-01

Muscular forces generated during locomotion depend on an animal's speed, gait, and size and underlie the energy demand to power locomotion. Changes in limb posture affect muscle forces by altering the mechanical advantage of the ground reaction force (R) and therefore the effective mechanical advantage (EMA = r/R, where r is the muscle mechanical advantage) for muscle force production. We used inverse dynamics based on force plate and kinematic recordings of humans as they walked and ran at steady speeds to examine how changes in muscle EMA affect muscle force-generating requirements at these gaits. We found a 68% decrease in knee extensor EMA when humans changed gait from a walk to a run compared with an 18% increase in hip extensor EMA and a 23% increase in ankle extensor EMA. Whereas the knee joint was extended (154-176 degrees) during much of the support phase of walking, its flexed position (134-164 degrees) during running resulted in a 5.2-fold increase in quadriceps impulse (time-integrated force during stance) needed to support body weight on the ground. This increase was associated with a 4.9-fold increase in the ground reaction force moment about the knee. In contrast, extensor impulse decreased 37% (P < 0.05) at the hip and did not change at the ankle when subjects switched from a walk to a run. We conclude that the decrease in limb mechanical advantage (mean limb extensor EMA) and increase in knee extensor impulse during running likely contribute to the higher metabolic cost of transport in running than in walking. The low mechanical advantage in running humans may also explain previous observations of a greater metabolic cost of transport for running humans compared with trotting and galloping quadrupeds of similar size.

A Telephone-based Physiotherapy Intervention for Patients with Osteoarthritis of the Knee

PubMed Central

Odole, Adesola C.; Ojo, Oluwatobi D.

2013-01-01

This study assessed the effects of a 6-week telephone based intervention on the pain intensity and physical function of patients with knee osteoarthritis (OA), and compared the results to physiotherapy conducted in the clinic. Fifty randomly selected patients with knee OA were assigned to one of two treatment groups: a clinic group (CG) and a tele-physiotherapy group (TG). The CG received thrice-weekly physiotherapist administered osteoarthritis-specific exercises in the clinic for six weeks. The TG received structured telephone calls thrice-weekly at home, to monitor self-administered osteoarthritis-specific exercises. Participants’ pain intensity and physical function were assessed at baseline, two, four, and six weeks, in the clinic environment. Within group comparison showed significant improvements across baseline, and at weeks two, four, and six for both TG and CG’s pain intensity and physical function. Between-group comparison of CG and TG’s pain intensity and physical function at baseline and weeks two, four, and six showed no significant differences. This study demonstrated that a six-week course of structured telephone calls thrice-weekly to patients at their home, to monitor self-administered osteoarthritis-specific exercises for patients with knee OA (i.e., tele-physiotherapy) achieved comparable results to physiotherapy conducted in the clinic. PMID:25945214

Recovery of voluntary and evoked muscle performance following intermittent-sprint exercise in the heat.

PubMed

Duffield, Rob; King, Monique; Skein, Melissa

2009-06-01

This study investigated the effects of hot conditions on the acute recovery of voluntary and evoked muscle performance and physiological responses following intermittent exercise. Seven youth male and six female team-sport athletes performed two sessions separated by 7 d, involving a 30-min exercise protocol and 60-min passive recovery in either 22 degrees C or 33 degrees C and 40% relative humidity. The exercise protocol involved a 20-s maximal sprint every 5 min, separated by constant-intensity exercise at 100 W on a cycle ergometer. Maximal voluntary contraction (MVC) and a resting evoked twitch (Pf) of the right knee extensors were assessed before and immediately following exercise and again 15, 30, and 60 min postexercise, and capillary blood was obtained at the same time points to measure lactate, pH, and HCO3. During and following exercise, core temperature, heart rate and rating of perceived exertion (RPE) were also measured. No differences (P=0.73 to 0.95) in peak power during repeated sprints were present between conditions. Postexercise MVC was reduced (P<.05) in both conditions and a moderate effect size (d=0.60) indicated a slower percentage MVC recovered by 60 min in the heat (83+/-10 vs 74+/-11% recovered). Both heart rate and core temperature were significantly higher (P<.05) during recovery in the heat. Capillary blood values did not differ between conditions at any time point, whereas sessional RPE was higher 60 min postexercise in the heat. The current data suggests that passive recovery in warm temperatures not only delays cardiovascular and thermal recovery, but may also slow the recovery of MVC and RPE.

The re-establishment of the normal blood lactate response to exercise in humans after prolonged acclimatization to altitude

PubMed Central

van Hall, G; Calbet, J A L; Søndergaard, H; Saltin, B

2001-01-01

One to five weeks of chronic exposure to hypoxia has been shown to reduce peak blood lactate concentration compared to acute exposure to hypoxia during exercise, the high altitude ‘lactate paradox’. However, we hypothesize that a sufficiently long exposure to hypoxia would result in a blood lactate and net lactate release from the active leg to an extent similar to that observed in acute hypoxia, independent of work intensity. Six Danish lowlanders (25–26 years) were studied during graded incremental bicycle exercise under four conditions: at sea level breathing either ambient air (0 m normoxia) or a low-oxygen gas mixture (10 % O2 in N2, 0 m acute hypoxia) and after 9 weeks of acclimatization to 5260 m breathing either ambient air (5260 m chronic hypoxia) or a normoxic gas mixture (47 % O2 in N2, 5260 m acute normoxia). In addition, one-leg knee-extensor exercise was performed during 5260 m chronic hypoxia and 5260 m acute normoxia. During incremental bicycle exercise, the arterial lactate concentrations were similar at sub-maximal work at 0 m acute hypoxia and 5260 m chronic hypoxia but higher compared to both 0 m normoxia and 5260 m acute normoxia. However, peak lactate concentration was similar under all conditions (10.0 ± 1.3, 10.7 ± 2.0, 10.9 ± 2.3 and 11.0 ± 1.0 mmol l−1) at 0 m normoxia, 0 m acute hypoxia, 5260 m chronic hypoxia and 5260 m acute normoxia, respectively. Despite a similar lactate concentration at sub-maximal and maximal workload, the net lactate release from the leg was lower during 0 m acute hypoxia (peak 8.4 ± 1.6 mmol min−1) than at 5260 m chronic hypoxia (peak 12.8 ± 2.2 mmol min−1). The same was observed for 0 m normoxia (peak 8.9 ± 2.0 mmol min−1) compared to 5260 m acute normoxia (peak 12.6 ± 3.6 mmol min−1). Exercise after acclimatization with a small muscle mass (one-leg knee-extensor) elicited similar lactate concentrations (peak 4.4 ± 0.2 vs. 3.9 ± 0.3 mmol l−1) and net lactate release (peak 16.4 ± 1.8 vs. 14.3 mmol l−1) from the active leg at 5260 m chronic hypoxia and 5260 m acute normoxia. In conclusion, in lowlanders acclimatized for 9 weeks to an altitude of 5260 m, the arterial lactate concentration was similar at 0 m acute hypoxia and 5260 m chronic hypoxia. The net lactate release from the active leg was higher at 5260 m chronic hypoxia compared to 0 m acute hypoxia, implying an enhanced lactate utilization with prolonged acclimatization to altitude. The present study clearly shows the absence of a lactate paradox in lowlanders sufficiently acclimatized to altitude. PMID:11691888

Sit-to-Stand Movement in Children with Hemiplegic Cerebral Palsy: Relationship with Knee Extensor Torque and Social Participation

ERIC Educational Resources Information Center

dos Santos, Adriana Neves; Pavao, Silvia Leticia; Santiago, Paulo Roberto Pereira; Salvini, Tania de Fatima; Rocha, Nelci Adriana Cicuto Ferreira

2013-01-01

This study aimed to investigate the relationship between sit-to-stand (STS) movement, knee extensor torque and social participation in children with cerebral palsy (CP). Seven spastic hemiplegic CP patients (8.0 plus or minus 2.2 years), classified by the Gross Motor Function Classification System as I and II, and 18 typical children (8.4 plus or…

Relation between Peak Power Output in Sprint Cycling and Maximum Voluntary Isometric Torque Production.

PubMed

Kordi, Mehdi; Goodall, Stuart; Barratt, Paul; Rowley, Nicola; Leeder, Jonathan; Howatson, Glyn

2017-08-01

From a cycling paradigm, little has been done to understand the relationships between maximal isometric strength of different single joint lower body muscle groups and their relation with, and ability to predict PPO and how they compare to an isometric cycling specific task. The aim of this study was to establish relationships between maximal voluntary torque production from isometric single-joint and cycling specific tasks and assess their ability to predict PPO. Twenty male trained cyclists participated in this study. Peak torque was measured by performing maximum voluntary contractions (MVC) of knee extensors, knee flexors, dorsi flexors and hip extensors whilst instrumented cranks measured isometric peak torque from MVC when participants were in their cycling specific position (ISOCYC). A stepwise regression showed that peak torque of the knee extensors was the only significant predictor of PPO when using SJD and accounted for 47% of the variance. However, when compared to ISOCYC, the only significant predictor of PPO was ISOCYC, which accounted for 77% of the variance. This suggests that peak torque of the knee extensors was the best single-joint predictor of PPO in sprint cycling. Furthermore, a stronger prediction can be made from a task specific isometric task. Copyright © 2017 Elsevier Ltd. All rights reserved.

Task-Specific and Functional Effects of Speed-Focused Elliptical or Motor-Assisted Cycle Training in Children With Bilateral Cerebral Palsy: Randomized Clinical Trial.

PubMed

Damiano, Diane L; Stanley, Christopher J; Ohlrich, Laurie; Alter, Katharine E

2017-08-01

Locomotor training using treadmills or robotic devices is commonly utilized to improve gait in cerebral palsy (CP); however, effects are inconsistent and fail to exceed those of equally intense alternatives. Possible limitations of existing devices include fixed nonvariable rhythm and too much limb or body weight assistance. To quantify and compare effectiveness of a motor-assisted cycle and a novel alternative, an elliptical, in CP to improve interlimb reciprocal coordination through intensive speed-focused leg training. A total of 27 children with bilateral CP, 5 to 17 years old, were randomized to 12 weeks of 20 minutes, 5 days per week home-based training (elliptical = 14; cycle = 13) at a minimum of 40 revolutions per minute, with resistance added when speed target was achieved. Primary outcomes were self-selected and fastest voluntary cadence on the devices and gait speed. Secondary outcomes included knee muscle strength, and selective control and functional mobility measures. Cadence on trained but not nontrained devices increased, demonstrating task specificity of training and increased exercise capability. Mean gait speed did not increase in either group, nor did parent-reported functional mobility. Knee extensor strength increased in both. An interaction between group and time was seen in selective control with scores slightly increasing for the elliptical and decreasing for the cycle, possibly related to tighter limb coupling with cycling. Task-specific effects were similarly positive across groups, but no transfer was seen to gait or function. Training dose was low (≤20 hours) compared with intensive upper-limb training recommendations and may be insufficient to produce appreciable clinical change.

Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship?

PubMed

Lanza, Marcel B; Balshaw, Thomas G; Folland, Jonathan P

2017-08-01

What is the central question of the study? Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship? What is the main finding and its importance? Both agonist (quadriceps) and antagonist coactivation (hamstrings) differed with knee joint angle during maximal isometric knee extensions and thus both are likely to contribute to the angle-torque relationship. Specifically, two independent measurement techniques showed quadriceps activation to be lower at more extended positions. These effects might influence the capacity for neural changes in response to training and rehabilitation at different knee joint angles. The influence of joint angle on knee extensor neuromuscular activation is unclear, owing in part to the diversity of surface electromyography (sEMG) and/or interpolated twitch technique (ITT) methods used. The aim of the study was to compare neuromuscular activation, using rigorous contemporary sEMG and ITT procedures, during isometric maximal voluntary contractions (iMVCs) of the quadriceps femoris at different knee joint angles and examine whether activation contributes to the angle-torque relationship. Sixteen healthy active men completed two familiarization sessions and two experimental sessions of isometric knee extension and knee flexion contractions. The experimental sessions included the following at each of four joint angles (25, 50, 80 and 106 deg): iMVCs (with and without superimposed evoked doublets); submaximal contractions with superimposed doublets; and evoked twitch and doublet contractions whilst voluntarily passive, and knee flexion iMVC at the same knee joint positions. The absolute quadriceps femoris EMG was normalized to the peak-to-peak amplitude of an evoked maximal M-wave, and the doublet-voluntary torque relationship was used to calculate activation with the ITT. Agonist activation, assessed with both normalized EMG and the ITT, was reduced at the more extended compared with the more flexed positions (25 and 50 versus 80 and 106 deg; P ≤ 0.016), whereas antagonist coactivation was greatest in the most flexed compared with the extended positions (106 versus 25 and 50 deg; P ≤ 0.02). In conclusion, both agonist and antagonist activation differed with knee joint angle during knee extension iMVCs, and thus both are likely to contribute to the knee extensor angle-torque relationship. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Aerobic exercise training lowers platelet reactivity and improves platelet sensitivity to prostacyclin in pre- and postmenopausal women.

PubMed

Lundberg Slingsby, M H; Nyberg, M; Egelund, J; Mandrup, C M; Frikke-Schmidt, R; Kirkby, N S; Hellsten, Y

2017-12-01

Essentials It is unknown how regular exercise affects platelet function after menopause. We studied the effect of 3-months of high-intensity exercise in pre- and postmenopausal women. Platelet sensitivity to the inhibitory effect of arterially infused prostacyclin was increased. Reduced basal platelet reactivity was seen in the premenopausal women only. Background The risk of atherothrombotic events increases after the menopause. Regular physical activity has been shown to reduce platelet reactivity in younger women, but it is unknown how regular exercise affects platelet function after the menopause. Objectives To examine the effects of regular aerobic exercise in late premenopausal and recent postmenopausal women by testing basal platelet reactivity and platelet sensitivity to prostacyclin and nitric oxide. Methods Twenty-five sedentary, but healthy, late premenopausal and 24 matched recently postmenopausal women, mean (95% confidence interval) 49.1 (48.2-49.9) and 53.7 (52.5-55.0) years old, participated in an intervention study: 3-month high-intensity supervised aerobic spinning-cycle training (1 h, × 3/week). Basal platelet reactivity was analyzed in platelet-rich plasma from venous blood as agonist-induced % aggregation. In a subgroup of 13 premenopausal and 14 postmenopausal women, platelet reactivity was tested ex vivo after femoral arterial infusion of prostacyclin, acetylcholine, a cyclooxygenase inhibitor, and after acute one-leg knee extensor exercise. Results Basal platelet reactivity (%aggregation) to TRAP-6 (1 μm) was higher in the postmenopausal, 59% (50-68), than the premenopausal women, 45% (35-55). Exercise training reduced basal platelet reactivity to collagen (1 μg mL -1 ) in the premenopausal women only: from 63% (55-71%) to 51% (41-62%). After the training intervention, platelet aggregation was more inhibited by the arterial prostacyclin infusion and the acute exercise in both premenopausal and postmenopausal women. Conclusions These results highlight previously unknown cardioprotective aspects of regular aerobic exercise in premenopausal and postmenopausal women, improving their regulation of platelet reactivity through an increased platelet sensitivity to prostacyclin, which may counterbalance the increased atherothrombotic risk associated with the menopause. © 2017 International Society on Thrombosis and Haemostasis.

Association Between Exercise Therapy Dose and Functional Improvements in the Early Postoperative Phase After Hip and Knee Arthroplasty: An Observational Study.

PubMed

Zech, Astrid; Hendrich, Simon; Pfeifer, Klaus

2015-10-01

To determine whether intensity and duration of standard exercise therapy are associated with changes in function after total hip arthroplasty (THA) and total knee arthroplasty (TKA). Prospective cohort study. Orthopedic inpatient rehabilitation center. A total of 123 patients 2 weeks after THA (n = 58; age, 62.5 ± 10.4 years) and TKA (n = 65; age, 66.6 ± 7.6 years). Standard rehabilitation (hands-on physiotherapy, group exercise therapy, strength training, cycle ergometer therapy, continuous passive motion therapy, and water exercise therapy). The Western Ontario and McMaster Universities Arthritis Index (WOMAC) and hip and knee range of motion (ROM) were assessed before and after inpatient rehabilitation. The individual rehabilitation period varied between 12-25 days and included 48.1 ± 12.5 (THA) or 41.9 ± 9.7 (TKA) exercise interventions with intensities between 9.6 and 14.0 points on the Borg Rate of Perceived Exertion Scale. WOMAC pain (P < .001), stiffness (P < .001), and function (P < .001), as well as hip (P < .001) and knee (P < .001) ROM, improved significantly in THA and TKA patients. Analysis of covariance showed that these changes could not be explained by the total duration or mean intensity of exercise therapy. The findings show a low dose-response relationship between early postoperative exercise therapy and the improvements in function or ROM after THA and TKA. Although the findings raise questions about the efficacy of existing rehabilitation programs, the small sample size, single setting, and geographic differences in postoperative treatment standards limit the generalizability of findings. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

A Novel Two-Velocity Method for Elaborate Isokinetic Testing of Knee Extensors.

PubMed

Grbic, Vladimir; Djuric, Sasa; Knezevic, Olivera M; Mirkov, Dragan M; Nedeljkovic, Aleksandar; Jaric, Slobodan

2017-09-01

Single outcomes of standard isokinetic dynamometry tests do not discern between various muscle mechanical capacities. In this study, we aimed to (1) evaluate the shape and strength of the force-velocity relationship of knee extensors, as observed in isokinetic tests conducted at a wide range of angular velocities, and (2) explore the concurrent validity of a simple 2-velocity method. Thirteen physically active females were tested for both the peak and averaged knee extensor concentric force exerted at the angular velocities of 30°-240°/s recorded in the 90°-170° range of knee extension. The results revealed strong (0.960

Relation between functional mobility and dynapenia in institutionalized frail elderly.

PubMed

Soares, Antonio Vinicius; Marcelino, Elessandra; Maia, Késsia Cristina; Borges, Noé Gomes

2017-01-01

To investigate the relation between functional mobility and dynapenia in institutionalized frail elderly. A descriptive, correlational study involving 26 institutionalized elderly men and women, mean age 82.3±6 years. The instruments employed were the Mini Mental State Examination, the Geriatric Depression Scale, the International Physical Activity Questionnaire, the Timed Up and Go test, a handgrip dynamometer and a portable dynamometer for large muscle groups (shoulder, elbow and hip flexors, knee extensors and ankle dorsiflexors). Significant negative correlation between functional mobility levels assessed by the Timed Up and Go test and dynapenia was observed in all muscle groups evaluated, particularly in knee extensors (r -0.65). A significant negative correlation between muscle strength, particularly knee extensor strength, and functional mobility was found in institutionalized elderly. Data presented indicate that the higher the muscle strength, the shorter the execution time, and this could demonstrate better performance in this functional mobility test.

Vascularised knee joint transplantation in man: the first two years experience.

PubMed

Kirschner, M H; Brauns, L; Gonschorek, O; Bühren, V; Hofmann, G O

2000-04-01

To describe our early experience with a new technique for restoring destroyed knee joints to give reasonable functional results. Observational clinical trial. Level-1-Trauma centre, Germany. 5 patients with large bone defects of the knee and loss of the extensor apparatus caused either by serious injury alone, or infection after serious injury. Transplantation of fresh and perfused knee joints with a vascular pedicle from multiorgan donors under immunosuppression. Ability to walk, need to remove one transplanted joint. Four patients are able to walk, the range of movement being from 50 degrees-120 degrees. The first patient additionally had to be provided with a total knee joint arthroplasty. In the third patient the graft became infected and had to be removed. She finally had an arthrodesis and bone lengthening by the Ilizarov technique. Transplantation of the knee joint may be an alternative to bone lengthening or amputation for patients with total loss of the extensor apparatus.

Crouch gait can be an effective form of forced-use/no constraint exercise for the paretic lower limb in stroke

PubMed Central

Rota, Viviana; Malloggi, Chiara; Brugliera, Luigia; Catino, Luigi

2017-01-01

In hemiplegic gait the paretic lower limb provides less muscle power and shows a briefer stance compared with the unaffected limb. Yet, a longer stance and a higher power can be obtained from the paretic lower limb if gait speed is increased. This supports the existence of a ‘learned non-use’ phenomenon, similar to that underlying some asymmetric impairments of the motion of the eyes and of the upper limbs. Crouch gait (CG) (bent-hip bent-knee, about 30° minimum knee flexion) might be an effective form of ‘forced-use’ treatment of the paretic lower limb. It is not known whether it also stimulates a more symmetric muscle power output. Gait analysis on a force treadmill was carried out in 12 healthy adults and seven hemiplegic patients (1–127 months after stroke, median: 1.6). Speed was imposed at 0.3 m/s. Step length and single and double stance times, sagittal joint rotations, peak positive power, and work in extension of the hip, knee, and ankle (plantar flexion), and surface electromyography (sEMG) area from extensor muscles during the generation of power were measured on either side during both erect and crouch walking. Significance was set at P less than 0.05; corrections for multiplicity were applied. Patients, compared with healthy controls, adopted in both gait modalities and on both sides a shorter step length (61–84%) as well as a shorter stance (76–90%) and swing (63–83%) time. As a rule, they also provided a higher muscular work (median: 137%, range: 77–250%) paralleled by a greater sEMG area (median: 174%, range: 75–185%). In erect gait, the generation of peak extensor power across hip, knee, and ankle joints was in general lower (83–90%) from the paretic limb and higher (98–165%) from the unaffected limb compared with control values. In CG, peak power generation across the three lower limb joints was invariably higher in hemiparetic patients: 107–177% from the paretic limb and 114–231% from the unaffected limb. When gait shifted from erect to crouch, only for hemiplegic patients, at the hip, the paretic/unaffected ratio increased significantly. For peak power, work, sEMG area, and joint rotation, the paretic/unaffected ratio increased from 55 to 85%, 56 to 72%, 68 to 91%, and 67 to 93%, respectively. CG appears to be an effective form of forced-use exercise eliciting more power and work from the paretic lower limb muscles sustained by a greater neural drive. It also seems effective in forcing a more symmetric power and work from the hip extensor muscles, but neither from the knee nor the ankle. PMID:28574860

Sagittal-Plane Knee Moment During Gait and Knee Cartilage Thickness

PubMed Central

Harrison, David; Wang, Hsin-Min; Shultz, Sandra J.

2017-01-01

Context:  Understanding the factors associated with thicker cartilage in a healthy population is important when developing strategies aimed at minimizing the cartilage thinning associated with knee osteoarthritis progression. Thicker articular cartilage is commonly thought to be healthier cartilage, but whether the sagittal-plane biomechanics important to gait are related to cartilage thickness is unknown. Objective:  To determine the relationship of a weight-bearing region of the medial femoral condyle's cartilage thickness to sagittal gait biomechanics in healthy individuals. Design:  Descriptive laboratory study. Setting:  Laboratory. Patients or Other Participants:  Twenty-eight healthy participants (15 women: age = 21.1 ± 2.1 years, height = 1.63 ± 0.07 m, weight = 64.6 ± 9.9 kg; 13 men: age = 22.1 ± 2.9 years, height = 1.79 ± 0.05 m, weight = 75.2 ± 9.6 kg). Main Outcome Measure(s):  Tibiofemoral angle (°) was obtained via goniometric assessment, thickness of the medial femoral condyle cartilage (mm) was obtained via ultrasound imaging, and peak internal knee-extensor moment (% body weight · height) was measured during 10 trials of over-ground walking at a self-selected pace. We used linear regression to examine the extent to which peak internal knee-extensor moment predicted cartilage thickness after accounting for tibiofemoral angle and sex. Results:  Sex and tibiofemoral angle (12.3° ± 3.2°) were entered in the initial step as control factors (R2 = 0.01, P = .872). In the final step, internal knee-extensor moment (1.5% ± 1.3% body weight · height) was entered, which resulted in greater knee-extensor moment being related to greater cartilage thickness (2.0 ± 0.3 mm; R2Δ = 0.31, PΔ = .003). Conclusion:  Individuals who walked with a greater peak internal knee-extensor moment during gait had a cartilage structure that is generally considered beneficial in a healthy population. Our study offers promising findings that a potentially modifiable biomechanical factor is associated with cartilage status in a healthy population. Establishing these baseline relationships in uninjured populations may help us to better understand potential factors related to maladaptive gait patterns that predispose a person to adverse changes in the cartilage environment. PMID:28653865

Muscle fascicle behavior during eccentric cycling and its relation to muscle soreness.

PubMed

Peñailillo, Luis; Blazevich, Anthony J; Nosaka, Kazunori

2015-04-01

A single bout of eccentric exercise confers a protective effect against muscle damage and soreness in subsequent eccentric exercise bouts, but the mechanisms underpinning this effect are unclear. This study compared vastus lateralis (VL) muscle-tendon behavior between two eccentric cycling bouts to test the hypothesis that muscle-tendon behavior would be different between bouts and would be associated with the protective effect. Eleven untrained men (27.1 ± 7.0 yr) performed two bouts of eccentric cycling (ECC1 and ECC2) separated by 2 wk for 10 min at 65% of maximal concentric workload (191.9 ± 44.2 W) each. Muscle soreness (by visual analog scale) and maximal voluntary isometric contraction (MVC) torque of the knee extensors were assessed before and 1-2 d after exercise. Using ultrasonography, VL fascicle length and angle changes during cycling were assessed, and tendinous tissue (TT) length changes were estimated. VL EMG amplitude, crank torque, and knee joint angles were measured during cycling. Soreness was greater (P < 0.0001) after ECC1 than ECC2, although MVC changes were not different between bouts (P = 0.47). No significant differences in peak EMG amplitude (normalized to EMG during MVC), crank peak torque, or knee angles were evident between bouts. However, fascicle elongation was 16% less during ECC2 than ECC1 (P < 0.01), indicating less fascicle strain in ECC2. Maximum TT length occurred at a smaller knee joint angle during ECC2 than ECC1 (P = 0.055). These results suggest that a lesser fascicle elongation and earlier TT elongation were associated with reduced muscle soreness after ECC2 than ECC1; thus, changes in muscle-tendon behavior may be an important mechanism underpinning the protective effect.

Effect of mirror use on lower extremity muscle strength of patients with chronic stroke.

PubMed

Kim, Myoung-Kwon; Choe, Yu-Won; Shin, Young-Jun; Peng, Cheng; Choi, Eun-Hong

2018-02-01

[Purpose] This study examines the effect on muscle strength of lower extremity muscle strength exercise while using a mirror on the non-paretic side in patients with chronic stroke. [Subjects and Methods] Subjects were randomly assigned to a non-mirror lower extremity exercise group (n=10), a mirror lower extremity exercise group (n=10), or a mirror lower extremity muscle strength exercise group (n=10). Subjects were asked to do the exercise assigned to their group (5 sets 30 times a day, 5 times weekly for 4 weeks) with general physical therapy in the hospital. Muscle strength in the knee extensor and flexor of paretic and non-paretic side were measured using electrical muscle testing device before and after the intervention. [Results] Muscle strength significantly increased within each group after intervention. No significant differences were found among the three groups. [Conclusion] This study showed that the lower extremity muscle strength exercise of the non-paretic side using a mirror has a positive effect on muscle strength in patient with chronic stroke.

A comparison of home-based exercise programs with and without self-manual therapy in individuals with knee osteoarthritis in community.

PubMed

Cheawthamai, Kornkamon; Vongsirinavarat, Mantana; Hiengkaew, Vimonwan; Saengrueangrob, Sasithorn

2014-07-01

The present study aimed to compare the effectiveness of the treatment programs of home-based exercise with and without self-manual therapy in individuals with knee osteoarthritis (knee OA) in community. Forty-three participants with knee OA were randomly assigned in groups. All participants received the same home-based exercise program with or without self-manual therapy over 12 weeks. Outcome measures were pain intensity, range of motions, six-minute walk test distance, the knee injury and osteoarthritis outcome score (KOOS), short-form 36 (SF-36) and satisfaction. The results showed that the self-manual therapy program significantly decreased pain at 4 weeks, increased flexion and extension at 4 and 12 weeks, and improved the KOOS in pain item and SF-36 in physical function and mental health items. The home-based exercise group showed significant increase of the six-minute walk distance at 4 and 12 weeks, improvements in the KOOS in pain and symptom items and SF-36 in the physical function and role-emotional items. Overall, the results favored a combination of self-manual therapy and home-based exercise for patients with knee OA, which apparently showed superior benefits in decreasing pain and improving active knee range of motions.

Effects of eccentric-focused and conventional resistance training on strength and functional capacity of older adults.

PubMed

Dias, Caroline Pieta; Toscan, Rafael; de Camargo, Mainara; Pereira, Evelyn Possobom; Griebler, Nathália; Baroni, Bruno Manfredini; Tiggemann, Carlos Leandro

2015-10-01

The aim of the study was to assess the effect of eccentric training using a constant load with longer exposure time at the eccentric phase on knee extensor muscle strength and functional capacity of elderly subjects in comparison with a conventional resistance training program. Twenty-six healthy elderly women (age = 67 ± 6 years) were randomly assigned to an eccentric-focused training group (ETG; n = 13) or a conventional training group (CTG; n = 13). Subjects underwent 12 weeks of resistance training twice a week. For the ETG, concentric and eccentric phases were performed using 1.5 and 4.5 s, respectively, while for CTG, each phase lasted 1.5 s. Maximum dynamic strength was assessed by the one-repetition maximum (1RM) test in the leg press and knee extension exercises, and for functional capacity, subjects performed specific tests (6-m walk test, timed up-and-go test, stair-climbing test, and chair-rising test). Both groups improved knee extension 1RM (24-26 %; p = 0.021), timed up-and-go test (11-16 %; p < 0.001), 6-m walk test (9-12 %; p = 0.004), stair-climbing test (8-13 %; p = 0.007), and chair-rising test (15-16 %; p < 0.001), but there was no significant difference between groups. In conclusion, the strategy of increasing the exposure time at the eccentric phase of movement using the same training volume and intensity does not promote different adaptations in strength or functional capacity compared to conventional resistance training in elderly woman.

Positron emission tomography detects greater blood flow and less blood flow heterogeneity in the exercising skeletal muscles of old compared with young men during fatiguing contractions

PubMed Central

Rudroff, Thorsten; Weissman, Jessica A; Bucci, Marco; Seppänen, Marko; Kaskinoro, Kimmo; Heinonen, Ilkka; Kalliokoski, Kari K

2014-01-01

The purpose of this study was to investigate blood flow and its heterogeneity within and among the knee muscles in five young (26 ± 6 years) and five old (77 ± 6 years) healthy men with similar levels of physical activity while they performed two types of submaximal fatiguing isometric contraction that required either force or position control. Positron emission tomography (PET) and [15O]-H2O were used to determine blood flow at 2 min (beginning) and 12 min (end) after the start of the tasks. Young and old men had similar maximal forces and endurance times for the fatiguing tasks. Although muscle volumes were lower in the older subjects, total muscle blood flow was similar in both groups (young men: 25.8 ± 12.6 ml min−1; old men: 25.1 ± 15.4 ml min−1; age main effect, P = 0.77) as blood flow per unit mass of muscle in the exercising knee extensors was greater in the older (12.5 ± 6.2 ml min−1 (100 g)−1) than the younger (8.6 ± 3.6 ml min−1 (100 g)−1) men (age main effect, P = 0.001). Further, blood flow heterogeneity in the exercising knee extensors was significantly lower in the older (56 ± 27%) than the younger (67 ± 34%) men. Together, these data show that although skeletal muscles are smaller in older subjects, based on the intact neural drive to the muscle and the greater, less heterogeneous blood flow per gram of muscle, old fit muscle achieves adequate exercise hyperaemia. Key points The results of previous studies that attempted to demonstrate the effects of ageing on skeletal muscle blood flow are controversial because these studies used indirect assessments of skeletal muscle blood flow obtained via whole limb blood flow measurements that provide no information on the distribution of blood flow within particular muscles. We used positron emission tomography to measure blood flow per gram of muscle in old and young men with similar levels of physical activity. Resting muscle blood flow was similar in both groups and exercising muscle blood flow was greater and less heterogeneous in the older men. Old and young men achieved similar maximal voluntary contraction forces and endurance times during two types of fatiguing isometric task. These findings indicate that physically active old men have intact neural drive to the muscle and achieve adequate exercise hyperaemia despite the age-induced decrease in their muscle volume. PMID:24247981

The interaction between the vastus medialis and vastus intermedius and its influence on the extensor apparatus of the knee joint.

PubMed

Grob, Karl; Manestar, Mirjana; Filgueira, Luis; Kuster, Markus S; Gilbey, Helen; Ackland, Timothy

2018-03-01

Although the vastus medialis (VM) is closely associated with the vastus intermedius (VI), there is a lack of data regarding their functional relationship. The purpose of this study was to investigate the anatomical interaction between the VM and VI with regard to their origins, insertions, innervation and function within the extensor apparatus of the knee joint. Eighteen human cadaveric lower limbs were investigated using macro-dissection techniques. Six limbs were cut transversely in the middle third of the thigh. The mode of origin, insertion and nerve supply of the extensor apparatus of the knee joint were studied. The architecture of the VM and VI was examined in detail, as was their anatomical interaction and connective tissue linkage to the adjacent anatomical structures. The VM originated medially from a broad hammock-like structure. The attachment site of the VM always spanned over a long distance between: (1) patella, (2) rectus femoris tendon and (3) aponeurosis of the VI, with the insertion into the VI being the largest. VM units were inserted twice-once on the anterior and once on the posterior side of the VI. The VI consists of a complex multi-layered structure. The layers of the medial VI aponeurosis fused with the aponeuroses of the tensor vastus intermedius and vastus lateralis. Together, they form the two-layered intermediate layer of the quadriceps tendon. The VM and medial parts of the VI were innervated by the same medial division of the femoral nerve. The VM consists of multiple muscle units inserting into the entire VI. Together, they build a potential functional muscular complex. Therefore, the VM acts as an indirect extensor of the knee joint regulating and adjusting the length of the extensor apparatus throughout the entire range of motion. It is of clinical importance that, besides the VM, substantial parts of the VI directly contribute to the medial pull on the patella and help to maintain medial tracking of the patella during knee extension. The interaction between the VM and VI, with responsibility for the extension of the knee joint and influence on the patellofemoral function, leads readily to an understanding of common clinical problems found at the knee joint as it attempts to meet contradictory demands for both mobility and stability. Surgery or trauma in the anteromedial aspect of the quadriceps muscle group might alter a delicate interplay between the VM and VI. This would affect the extensor apparatus as a whole.

Stance control knee mechanism for lower-limb support in hybrid neuroprosthesis

PubMed Central

To, Curtis S.; Kobetic, Rudi; Bulea, Thomas C.; Audu, Musa L.; Schnellenberger, John R.; Pinault, Gilles; Triolo, Ronald J.

2014-01-01

A hydraulic stance control knee mechanism (SCKM) was developed to fully support the knee against flexion during stance and allow uninhibited motion during swing for individuals with paraplegia using functional neuromuscular stimulation (FNS) for gait assistance. The SCKM was optimized for maximum locking torque for body-weight support and minimum resistance when allowing for free knee motion. Ipsilateral and contralateral position and force feedback were used to control the SCKM. Through bench and nondisabled testing, the SCKM was shown to be capable of supporting up to 70 N-m, require no more than 13% of the torque achievable with FNS to facilitate free motion, and responsively and repeatedly unlock under an applied flexion knee torque of up to 49 N-m. Preliminary tests of the SCKM with an individual with paraplegia demonstrated that it could support the body and maintain knee extension during stance without the stimulation of the knee extensor muscles. This was achieved without adversely affecting gait, and knee stability was comparable to gait assisted by knee extensor stimulation during stance. PMID:21938668

The effects of therapeutic exercises on pain, muscle strength, functional capacity, balance and hemodynamic parameters in knee osteoarthritis patients: a randomized controlled study of supervised versus home exercises.

PubMed

Kuru Çolak, Tuğba; Kavlak, Bahar; Aydoğdu, Onur; Şahin, Emir; Acar, Gönül; Demirbüken, İlkşan; Sarı, Zübeyir; Çolak, İlker; Bulut, Güven; Polat, M Gülden

2017-03-01

The aim of the study was to compare the effects of low-intensity exercise programs for lower extremities, either supervised or at home, on pain, muscle strength, balance and the hemodynamic parameters of knee osteoarthritis (OA) patients. This randomized study included 78 patients with knee OA in 2 groups of supervised and home-based exercise program. Exercises were applied to the first group in the clinic as a group exercise program and were demonstrated to the second group to be performed at home. Before and after the 6-week exercise program, assessment was made of pain, quadriceps and hamstring muscle strengths, 6-min walk test (6MWT), and non-invasive hemodynamic parameters. Results of the 78 patients, 56 completed the study. Pain, muscle strength, and 6MWT scores showed significant improvements in both groups. There were also significant differences in the amount of change in pain and muscle strength (pain: p = 0.041, Rqdc: 0.009, Lqdc: 0.013, Rhms: 0.04) which indicated greater improvements in the supervised group. The balance scores of supervised group showed a significant improvement (p = 0.009). No significant change was determined in hemodynamic parameters of either group. Conclusion according to the results of this study showed that low-intensity lower extremity exercises conducted in a clinic under the supervision of a physiotherapist were more effective than home-based exercises in reducing post-activity pain levels and improving quadriceps and right hamstring muscle strength. Both the supervised and home exercise programs were seen to be effective in reducing rest pain and increasing 6 MW distance in knee osteoarthritis patients.

High-intensity aquatic exercises (HydrOS) improve physical function and reduce falls among postmenopausal women.

PubMed

Moreira, Linda Denise Fernandes; Fronza, Fernanda Cerveira Abuana Osorio; dos Santos, Rodrigo Nolasco; Teixeira, Luzimar Raimundo; Kruel, Luis Fernando Martins; Lazaretti-Castro, Marise

2013-10-01

This study aims to investigate the effects of an aquatic exercise program (HydrOS) on neuromuscular function and falls among postmenopausal women. One hundred eight postmenopausal women (mean [SD] age, 58.8 [6.4] y) were randomly divided into the control group (CG; n = 44) and the aquatic exercise group (AEG; n = 64). Both groups received elementary calcium 500 mg/day and cholecalciferol 1,000 IU/day. For 24 weeks, the AEG participated in the aquatic exercise program, whereas the CG remained sedentary. The following variables were measured before and after the program: number of falls and fallers (7 mo before and after the intervention); flexibility, using Wells' Sit-and-Reach Test (FLEX); static balance, using the Unipedal Stance Test (UST); mobility, using the Timed-Up-and-Go test (TUG); handgrip strength of the dominant hand (HGS); and maximal isometric strength of back extensor muscles (SBE), strength of hip flexor muscles (SHF), and strength of knee extensor muscles (SKE). The muscle strength tests were considered the primary outcome, whereas the other neuromuscular tests, together with falls, were considered secondary outcomes. Results were significant when P ≤ 0.05. Serum 25-hydroxyvitamin D significantly increased by 21% in the CG and by 23% in the AEG (P < 0.001). The number of falls and fallers after the program remained unchanged in the CG; in the AEG, the mean number of falls decreased from 2.00 to 0.29 (P < 0.0001), and the number of fallers decreased by 44% (P < 0.0001). All neuromuscular variables significantly improved in the AEG: FLEX (26.6%; P < 0.0001), UST (14.1%; P < 0.001), TUG (23.7%; P < 0.001), HGS (13.4%; P < 0.001), SBE (26.2%; P < 0.001), SHF (18.5%; P = 0.039), and SKE (7.7%; P < 0.001). In the CG, significant improvements in FLEX (12.2%; P = 0.009), UST (4.5%; P < 0.001), TUG (10%; P < 0.001), and SHF (5.7%; P = 0.039) were observed and could be explained by increasing serum 25-hydroxyvitamin D level attributable to supplementation. The aquatic exercise program HydrOS is a safe and efficient way to improve physical function and to reduce falls among postmenopausal women.

A Randomized Clinical Trial to Assess the Effect of Statins on Skeletal Muscle Function and Performance: Rationale and Study Design

PubMed Central

Thompson, Paul D.; Parker, Beth A.; Clarkson, Priscilla M.; Pescatello, Linda S.; White, C. Michael; Grimaldi, Adam S.; Levine, Benjamin D.; Haller, Ronald G.; Hoffman, Eric P.

2014-01-01

Hydroxymethylglutaryl-coenzyme A reductase inhibitors or statins are the most effective medications for reducing elevated concentrations of low-density lipoprotein cholesterol (LDL-C). Statins reduce cardiac events in patients with coronary artery disease and previously healthy persons. Current recommendations for LDL-C treatment goals indicate that more patients will be treated with higher doses of these medications. Statins have been extremely well-tolerated in controlled clinical trials but are increasingly recognized to produce skeletal muscle myalgia, cramps, and weakness. The reported frequency of such mild symptoms is not clear, and muscle performance has not been examined with these medications. Accordingly, the present investigation, the Effect of Statins on Skeletal Muscle Function and Performance (STOMP) study, will recruit approximately 440 healthy persons. Participants will be randomly assigned to treatment with atorvastatin 80 mg/d or placebo. Handgrip, elbow and knee isometric and isokinetic strength, knee extensor endurance, and maximal aerobic exercise performance will be determined at baseline. Participants will undergo repeat testing after 6 months of treatment or after meeting the study definition of statin myalgia. This study will determine the effect of statins on skeletal muscle strength, endurance, and aerobic exercise performance and may ultimately help clinicians better evaluate statin-related muscle and exercise complaints. PMID:20626664

Effect of Preactivation on Torque Enhancement by the Stretch-Shortening Cycle in Knee Extensors

PubMed Central

Fukutani, Atsuki; Misaki, Jun; Isaka, Tadao

2016-01-01

The stretch-shortening cycle is one of the most interesting topics in the field of sport sciences, because the performance of human movement is enhanced by the stretch-shortening cycle (eccentric contraction). The purpose of the present study was to examine whether the influence of preactivation on the torque enhancement by stretch-shortening cycle in knee extensors. Twelve men participated in this study. The following three conditions were conducted for knee extensors: (1) concentric contraction without preactivation (CON), (2) concentric contraction with eccentric preactivation (ECC), and (3) concentric contraction with isometric preactivation (ISO). Muscle contractions were evoked by electrical stimulation to discard the influence of neural activity. The range of motion of the knee joint was set from 80 to 140 degrees (full extension = 180 degrees). Angular velocities of the concentric and eccentric contractions were set at 180 and 90 degrees/s, respectively. In the concentric contraction phase, joint torques were recorded at 85, 95, and 105 degrees, and they were compared among the three conditions. In the early phase (85 degrees) of concentric contraction, the joint torque was larger in the ECC and ISO conditions than in the CON condition. However, these clear differences disappeared in the later phase (105 degrees) of concentric contraction. The results showed that joint torque was clearly different among the three conditions in the early phase whereas this difference disappeared in the later phase. Thus, preactivation, which is prominent in the early phase of contractions, plays an important role in torque enhancement by the stretch-shortening cycle in knee extensors. PMID:27414804

Effects of Intensive Diet and Exercise on Knee Joint Loads, Inflammation, and Clinical Outcomes Among Overweight and Obese Adults With Knee Osteoarthritis

PubMed Central

Messier, Stephen P.; Mihalko, Shannon L.; Legault, Claudine; Miller, Gary D.; Nicklas, Barbara J.; DeVita, Paul; Beavers, Daniel P.; Hunter, David J.; Lyles, Mary F.; Eckstein, Felix; Williamson, Jeff D.; Carr, J. Jeffery; Guermazi, Ali; Loeser, Richard F.

2015-01-01

IMPORTANCE Knee osteoarthritis (OA), a common cause of chronic pain and disability, has biomechanical and inflammatory origins and is exacerbated by obesity. OBJECTIVE To determine whether a ≥10% reduction in body weight induced by diet, with or without exercise, would improve mechanistic and clinical outcomes more than exercise alone. DESIGN, SETTING, AND PARTICIPANTS Single-blind, 18-month, randomized clinical trial at Wake Forest University between July 2006 and April 2011. The diet and exercise interventions were center-based with options for the exercise groups to transition to a home-based program. Participants were 454 overweight and obese older community-dwelling adults (age ≥55 years with body mass index of 27–41) with pain and radiographic knee OA. INTERVENTIONS Intensive diet-induced weight loss plus exercise, intensive diet-induced weight loss, or exercise. MAIN OUTCOMES AND MEASURES Mechanistic primary outcomes: knee joint compressive force and plasma IL-6 levels; secondary clinical outcomes: self-reported pain (range, 0–20), function (range, 0–68), mobility, and health-related quality of life (range, 0–100). RESULTS At 18 months, 399 participants (88%) completed the study. Compared with exercise participants, knee compressive forces were lower in diet participants and IL-6 levels were lower in diet and diet + exercise participants. 18-mo Outcomes, Mean (95% CI) Exercise(E) Diet (D) D + E Difference,E vs D Difference, Evs D+E Weight loss, kg −1.8(−5.7to1.8) −8.9(−12.4 to −5.3) −10.6(−14.1 to −7.1) Knee compressiveforces, N 2687(2590 to 2784) 2487(2393 to 2581) 2543(2448 to 2637) 200(55 to 345)a 144(1 to 287) IL-6, pg/mL 3.1(2.9 to 3.4) 2.7(2.4 to 3.0) 2.7(2.5 to 3.0) 0.43(0.01 to 0.85)a 0.39(−0.03 to 0.81)a Pain 4.7(4.2 to 5.1) 4.8(4.3 to 5.2) 3.6(3.2 to 4.1) −0.11(−0.81 to 0.59) 1.02(0.33 to 1.71)a Function 18.4(16.9 to 19.9) 17.4(15.9 to 18.9) 14.1(12.6 to 15.6) 0.98(−1.24 to 3.20) 4.29(2.07 to 6.50)a SF-36 physical 41.9(40.5 to 43.2) 42.4(41.1 to 43.7) 44.7(43.4 to 46.0) −0.55(−2.53 to 1.43) −2.81(−4.76 to −0.86)a a Differences were significant. CONCLUSIONS AND RELEVANCE Among overweight and obese adults with knee OA, after 18 months, participants in the diet + exercise and diet groups had more weight loss and greater reductions in IL-6 levels than those in the exercise group; those in the diet group had greater reductions in knee compressive force than those in the exercise group. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00381290 PMID:24065013

A lower extremity strength-based profile of NCAA Division I women's basketball and gymnastics athletes: implications for knee joint injury risk assessment.

PubMed

Thompson, Brennan J; Cazier, Curtis S; Bressel, Eadric; Dolny, Dennis G

2018-08-01

This study aimed to provide a comprehensive strength-based physiological profile of women's NCAA Division I basketball and gymnastic athletes; and to make sport-specific comparisons for various strength characteristics of the knee flexor and extensor muscles. A focus on antagonist muscle balance (hamstrings-to-quadriceps ratios, H:Q) was used to elucidate vulnerabilities in these at-risk female athletes. Fourteen NCAA Division I women's basketball and 13 gymnastics athletes performed strength testing of the knee extensors and flexors. Outcome measures included absolute and relative (body mass normalised) peak torque (PT), rate of torque development at 50, 100, 200 ms (RTD50 etc.) and H:Q ratios of all variables. The basketball athletes had greater absolute strength for all variables except for isokinetic PT at 240°s -1 and isometric RTD50 for the knee extensors. Gymnasts showed ~20% weaker body mass relative concentric PT for the knee flexors at 60 and 120°·s -1 , and decreased conventional H:Q ratios at 60 and 240°·s -1 (~15%). These findings suggest that collegiate level gymnastics athletes may be prone to increased ACL injury risk due to deficient knee flexor strength and H:Q strength imbalance. Coaches may use these findings when implementing injury prevention screening and/or for individualised strength training programming centered around an athletes strength-related deficits.

Characteristics of fast voluntary and electrically evoked isometric knee extensions during 56 days of bed rest with and without exercise countermeasure

PubMed Central

Gerrits, K. H. L.; Rittweger, J.; Felsenberg, D.; Stegeman, D. F.; de Haan, A.

2008-01-01

The contractile characteristics of fast voluntary and electrically evoked unilateral isometric knee extensions were followed in 16 healthy men during 56 days of horizontal bed rest and assessed at bed rest days 4, 7, 10, 17, 24, 38 and 56. Subjects were randomized to either an inactive control group (Ctrl, n = 8) or a resistive vibration exercise countermeasure group (RVE, n = 8). No changes were observed in neural activation, indicated by the amplitude of the surface electromyogram, or the initial rate of voluntary torque development in either group during bed rest. In contrast, for Ctrl, the force oscillation amplitude at 10 Hz stimulation increased by 48% (P < 0.01), the time to reach peak torque at 300 Hz stimulation decreased by 7% (P < 0.01), and the half relaxation time at 150 Hz stimulation tended to be slightly reduced by 3% (P = 0.056) after 56 days of bed rest. No changes were observed for RVE. Torque production at 10 Hz stimulation relative to maximal (150 Hz) stimulation was increased after bed rest for both Ctrl (15%; P < 0.05) and RVE (41%; P < 0.05). In conclusion, bed rest without exercise countermeasure resulted in intrinsic speed properties of a faster knee extensor group, which may have partly contributed to the preserved ability to perform fast voluntary contractions. The changes in intrinsic contractile properties were prevented by resistive vibration exercise, and voluntary motor performance remained unaltered for RVE subjects as well. PMID:18386049

Effect of Exercise Type During Intentional Weight Loss on Body Composition in Older Adults with Obesity.

PubMed

Beavers, Kristen M; Ambrosius, Walter T; Rejeski, W Jack; Burdette, Jonathan H; Walkup, Michael P; Sheedy, Jessica L; Nesbit, Beverly A; Gaukstern, Jill E; Nicklas, Barbara J; Marsh, Anthony P

2017-11-01

To examine the long-term effects of exercise modality during weight loss on body composition and associations between body composition and physical function changes. Two hundred forty-nine older adults (66.9 ± 4.7 years, 71% women, 32% African American, BMI: 34.4 ± 3.7 kg/m 2 ) were randomized to weight loss (WL; n = 82), WL plus aerobic training (WL + AT; n = 86), or WL plus resistance training (WL + RT; n = 81) for 18 months. Dual-energy x-ray absorptiometry-acquired body composition, 400-m walk time, and knee extensor strength were measured at baseline and at 6 and 18 months. Total body mass loss was enhanced when WL was combined with exercise (WL: -5.7 ± 0.7 kg, WL + AT: -8.5 ± 0.7 kg, WL + RT: -8.7 ± 0.7 kg; P < 0.01). Total body fat mass loss was significantly greater in WL + AT (-6.8 ± 0.6 kg, -16.4%) and WL + RT (-7.8 ± 0.5 kg, -19.0%) than WL (-4.8 ± 0.6 kg, -10.9%); both P < 0.01. Lean mass loss was greatest in WL + AT (-1.6 ± 0.3 kg, -3.1%) compared with WL + RT (-0.8 ± 0.3 kg, -1.5%) or WL (-1.0 ± 0.3 kg; -2.0%); both P ≤ 0.02. Change in 400-m walk time was associated with change in fat mass (β/SD = +6.1 s; P < 0.01), while change in knee extensor strength was associated with change in lean mass (β/SD = +1.6 Nm; P < 0.01). WL + RT results in less lean mass lost than WL + AT; WL plus exercise yields greater fat mass loss than WL alone. © 2017 The Obesity Society.

Creatine supplementation during pulmonary rehabilitation in chronic obstructive pulmonary disease

PubMed Central

Fuld, J; Kilduff, L; Neder, J; Pitsiladis, Y; Lean, M; Ward, S; Cotton, M

2005-01-01

Background: Skeletal muscle wasting and dysfunction are strong independent predictors of mortality in patients with chronic obstructive pulmonary disease (COPD). Creatine nutritional supplementation produces increased muscle mass and exercise performance in health. A controlled study was performed to look for similar effects in 38 patients with COPD. Methods: Thirty eight patients with COPD (mean (SD) forced expiratory volume in 1 second (FEV1) 46 (15)% predicted) were randomised to receive placebo (glucose polymer 40.7 g) or creatine (creatine monohydrate 5.7 g, glucose 35 g) supplements in a double blind trial. After 2 weeks loading (one dose three times daily), patients participated in an outpatient pulmonary rehabilitation programme combined with maintenance (once daily) supplementation. Pulmonary function, body composition, and exercise performance (peripheral muscle strength and endurance, shuttle walking, cycle ergometry) took place at baseline (n = 38), post loading (n = 36), and post rehabilitation (n = 25). Results: No difference was found in whole body exercise performance between the groups: for example, incremental shuttle walk distance mean –23.1 m (95% CI –71.7 to 25.5) post loading and –21.5 m (95% CI –90.6 to 47.7) post rehabilitation. Creatine increased fat-free mass by 1.09 kg (95% CI 0.43 to 1.74) post loading and 1.62 kg (95% CI 0.47 to 2.77) post rehabilitation. Peripheral muscle performance improved: knee extensor strength 4.2 N.m (95% CI 1.4 to 7.1) and endurance 411.1 J (95% CI 129.9 to 692.4) post loading, knee extensor strength 7.3 N.m (95% CI 0.69 to 13.92) and endurance 854.3 J (95% CI 131.3 to 1577.4) post rehabilitation. Creatine improved health status between baseline and post rehabilitation (St George's Respiratory Questionnaire total score –7.7 (95% CI –14.9 to –0.5)). Conclusions: Creatine supplementation led to increases in fat-free mass, peripheral muscle strength and endurance, health status, but not exercise capacity. Creatine may constitute a new ergogenic treatment in COPD. PMID:15994258

Combined effects of functionally-oriented exercise regimens and nutritional supplementation on both the institutionalised and free-living frail elderly (double-blind, randomised clinical trial).

PubMed

Zak, Marek; Swine, Christian; Grodzicki, Tomasz

2009-01-28

Consistently swelling proportion of the frail elderly within a modern society challenges the overstrained public health sector to provide both adequate medical care and comprehensive assistance in their multiple functional deficits of daily living. Easy-to-apply and task-specific ways of addressing this issue are being sought out, with a view to proposing systemic solutions for nationwide application. The present randomised, double-blind, placebo-controlled, 7-week clinical trial aimed to determine whether specifically structured, intensive exercise regimens, combined with nutritional supplementation, might improve and help sustain individual muscle strength and mobility, and possibly enhance individual functional capabilities in an on-going quest for active prevention of care-dependency. Ninety-one frail elderly (F 71 M 20; mean age 79 years) were recruited from both nursing home residents and community dwellers and randomly split into four groups: Group I - progressive resistance exercises (PRE) + functionally-oriented exercises (FOE) + nutritional supplementation (NS), Group II - PRE + FOE + placebo, Group III--standard exercises (SE) + FOE + NS, Group IV - SE + FOE + placebo. Each group pursued a 45 min. exercise session 5 times weekly. The subjects' strength with regard to four muscle groups, i.e. hip and knee extensors and flexons, was assessed at 80% (1 RM) weekly, whereas their balance and mobility at baseline and at the end of the study. The study was completed by 80 subjects. Despite its relatively short duration significant differences in muscle strength were noted both in Group I and Group II (p = 0.01; p = 0.04; respectively), although this did not translate directly into perceptible improvement in individual mobility. Notable improvements in individual mobility were reported in Group III and Group IV (p = 0.002), although without positive impact on individual muscle strength. Comprehensively structured, high-intensity regimen made up of diverse exercise types, i.e. functionally-oriented, progressive resistance and standard ones, preferably if combined with nutritional supplementation in adequate volume, demonstrates clear potential for appreciably improving overall functional status in the frail elderly in terms of individual walking capacity and muscle strength. Central Register of Clinical Trials, Poland--CEBK180/2000.

Muscle damage and adaptation after the second bout of eccentric exercise of the knee extensors.

PubMed

Hassan, E S

2014-10-01

This study examined the muscles ability to adapt to eccentric exercise by the changes in serum myoglobin (Mb), creatine kinase (CK) activity and muscle soreness. The study involved 54 healthy young men from the 23± 2yr age group. These were distributed as subjects for three types of experiments with 18 men in each. Subjects performed 300 maximal eccentric exercises. In experiment I, after performing the first bout of exercise, they were split into three subgroups to perform the second bout after a period of 4, 6, and 8 weeks (WK), respectively. In experiment II, performed the second exercise after a period of 2, 3, and 5 wk, respectively. In experiment III, they performed four exercise bouts spaced 1 wk apart. in experiment II a significant (P<0.05) decrease in muscle soreness, serum Mb and CK was found on exercise bout 2. In experiment III, serum CK, Mb and muscle soreness responses were highest following bout 1. It was concluded that performance of a single exercise bout had a prophylactic effect on muscle soreness and serum protein responses that lasts approximately 2 wk, with the greatest adaptation occurring after one bout.

Effects of Lumbar Strengthening Exercise in Lower-Limb Amputees With Chronic Low Back Pain.

PubMed

Shin, Min Kyung; Yang, Hee Seung; Yang, Hea-Eun; Kim, Dae Hyun; Ahn, Bo Ram; Kwon, Hyup; Lee, Ju Hwan; Jung, Suk; Choi, Hyun Chul; Yun, Sun Keaung; Ahn, Dong Young; Sim, Woo Sob

2018-02-01

To analyze the effect of lumbar strengthening exercise in lower-limb amputees with chronic low back pain. We included in this prospective study 19 lower-limb amputees who had experienced low back pain for longer than 6 months. Participants were treated with 30-minute lumbar strengthening exercises, twice weekly, for 8 weeks. We used the visual analog scale (VAS), and Oswestry low back pain disability questionnaire, and measured parameters such as iliopsoas length, abdominal muscle strength, back extensor strength, and back extensor endurance. In addition, we assessed the isometric peak torque and total work of the trunk flexors and extensors using isokinetic dynamometer. The pre- and post-exercise measurements were compared. Compared with the baseline, abdominal muscle strength (from 4.4±0.7 to 4.8±0.6), back extensor strength (from 2.6±0.6 to 3.5±1.2), and back extensor endurance (from 22.3±10.7 to 46.8±35.1) improved significantly after 8 weeks. The VAS decreased significantly from 4.6±2.2 to 2.6±1.6 after treatment. Furthermore, the peak torque and total work of the trunk flexors and extensors increased significantly (p<0.05). Lumbar strengthening exercise in lower-limb amputees with chronic low back pain resulted in decreased pain and increased lumbar extensor strength. The lumbar strengthening exercise program is very effective for lower-limb amputees with chronic low back pain.

Effect of Lumbar Progressive Resistance Exercise on Lumbar Muscular Strength and Core Muscular Endurance in Soldiers.

PubMed

Mayer, John M; Childs, John D; Neilson, Brett D; Chen, Henian; Koppenhaver, Shane L; Quillen, William S

2016-11-01

Low back pain is common, costly, and disabling for active duty military personnel and veterans. The evidence is unclear on which management approaches are most effective. The purpose of this study was to assess the effectiveness of lumbar extensor high-intensity progressive resistance exercise (HIPRE) training versus control on improving lumbar extension muscular strength and core muscular endurance in soldiers. A randomized controlled trial was conducted with active duty U.S. Army Soldiers (n = 582) in combat medic training at Fort Sam Houston, Texas. Soldiers were randomized by platoon to receive the experimental intervention (lumbar extensor HIPRE training, n = 298) or control intervention (core stabilization exercise training, n = 284) at one set, one time per week, for 11 weeks. Lumbar extension muscular strength and core muscular endurance were assessed before and after the intervention period. At 11-week follow-up, lumbar extension muscular strength was 9.7% greater (p = 0.001) for HIPRE compared with control. No improvements in core muscular endurance were observed for HIPRE or control. Lumbar extensor HIPRE training is effective to improve isometric lumbar extension muscular strength in U.S. Army Soldiers. Research is needed to explore the clinical relevance of these gains. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

Isokinetic Assessment and Musculoskeletal Complaints in Paralympic Athletes: A Longitudinal Study.

PubMed

Silva, Andressa; Zanca, Gisele; Alves, Eduardo Silva; Lemos, Valdir de Aquino; Gávea, Sebastião Augusto; Winckler, Ciro; Mattiello, Stela Márcia; Peterson, Ronnie; Vital, Roberto; Tufik, Sergio; De Mello, Marco Túlio

2015-10-01

The aim of this study was to assess and monitor the peak torque of the knee extensor and flexor muscles in flexion and extension and the reports of musculoskeletal complaints in members of the main Brazilian Paralympic athletics team through 1 yr. Fourteen healthy athletes from both sexes were assessed three times in 1 yr. The volunteers were assessed for the presence of musculoskeletal complaints and muscle strength at three time points: (1) at the onset of the preparatory phase on December 2009, (2) at a follow-up assessment on June 2010, and (3) before actual competition on December 2010. The athletes' self-reported musculoskeletal complaints were assessed in structured interviews, and the muscle strength was assessed by means of isokinetic dynamometry. The knee flexor and extensor muscle strength exhibited significant increase in both the right and left lower limbs at the second and third assessments compared with the first one (P < 0.05). Muscle imbalance was associated with knee and thigh complaints at all three assessments (P < 0.05). The knee flexor and extensor muscle strength exhibited a gradual increase in both lower limbs during the course of the three assessments. In parallel, muscle imbalance was associated with the occurrence of knee and thigh complaints.

Hip Strength in Patients with Quadriceps Strength Deficits after ACL Reconstruction.

PubMed

Bell, David R; Trigsted, Stephanie M; Post, Eric G; Walden, Courtney E

2016-10-01

Quadriceps strength deficits persist for years after anterior cruciate ligament (ACL) reconstruction, and patients with these deficits often shift torque demands away from the knee extensors to the hip during functional tasks. However, it is not clear how quadriceps strength deficits may affect hip strength. Therefore, the purpose of this study was to investigate differences in lower extremity strength in individuals with ACL reconstruction with differing levels of quadriceps strength asymmetry. Isometric strength was recorded bilaterally in 135 participants (73 control and 62 with unilateral ACL reconstruction, time from surgery = 30.9 ± 17.6 months) from the knee extensors and flexors, hip extensors and abductors, and hip internal and external rotator muscle groups. Symmetry indices (limb symmetry index (LSI)) were created based on quadriceps strength, and subjects with ACL reconstruction were subdivided (high quadriceps (LSI ≥ 90%), n = 37; low quadriceps (LSI < 85%), n = 18). Individual group (control vs high quadriceps vs low quadriceps) by limb (reconstructed/nondominant vs healthy/dominant) repeated-measures ANOVA was used to compare strength (%BW) for each of the six joint motions of interest (knee extensors/flexors, hip abductors/extensors/external, and internal rotators) while controlling for time from surgery. An interaction was observed for quadriceps strength (P < 0.001), and the reconstructed limb in the low quadriceps group was weaker than all other limbs. A main effect for group was observed with the low quadriceps group having greater hip extension (P = 0.007) strength in both limbs compared with the other groups. Knee flexion strength was weaker in the reconstructed limb of the high quadriceps group (P = 0.047) compared with all other groups and limbs. Individuals with ACL reconstruction and involved limb quadriceps weakness have greater hip extension strength in both limbs compared with patients with bilateral strength symmetry and controls.

Limb salvage after infected knee arthroplasty with bone loss and extensor mechanism deficiency using a modular segmental replacement system.

PubMed

Namdari, Surena; Milby, Andrew H; Garino, Jonathan P

2011-09-01

Multiple total knee arthroplasty revisions pose significant surgical challenges, such as bone loss and soft tissue compromise. For patients with bone loss and extensor mechanism insufficiency after total knee arthroplasty, arthrodesis is a treatment option for the avoidance of amputation. However, arthrodesis is both difficult to achieve in situations with massive bone loss and potentially undesirable due to the dramatic shortening that follows. Although intramedullary nailing for knee arthrodesis has been widely reported, this technique has traditionally relied on the achievement of bony union. We report a case of a patient with massive segmental bone loss in which a modular intercalary prosthesis was used for arthrodesis to preserve limb length without bony union. Copyright © 2011 Elsevier Inc. All rights reserved.

Effects of Different Types of Exercise on Body Composition, Muscle Strength, and IGF-1 in the Elderly with Sarcopenic Obesity.

PubMed

Chen, Hung-Ting; Chung, Yu-Chun; Chen, Yu-Jen; Ho, Sung-Yen; Wu, Huey-June

2017-04-01

To investigate the influence of resistance training (RT), aerobic training (AT), or combination training (CT) interventions on the body composition, muscle strength performance, and insulin-like growth factor 1 (IGF-1) of patients with sarcopenic obesity. Randomized controlled trial. Community center and research center. Sixty men and women aged 65-75 with sarcopenic obesity. Participants were randomly assigned to RT, AT, CT, and control (CON) groups. After training twice a week for 8 weeks, the participants in each group ceased training for 4 weeks before being examined for the retention effects of the training interventions. The body composition, grip strength, maximum back extensor strength, maximum knee extensor muscle strength, and blood IGF-1 concentration were measured. The skeletal muscle mass (SMM), body fat mass, appendicular SMM/weight %, and visceral fat area (VFA) of the RT, AT, and CT groups were significantly superior to those of the CON group at both week 8 and week 12. Regarding muscle strength performance, the RT group exhibited greater grip strength at weeks 8 and 12 as well as higher knee extensor performance at week 8 than that of the other groups. At week 8, the serum IGF-1 concentration of the RT group was higher than the CON group, whereas the CT group was superior to the AT and CON groups. Older adults with sarcopenic obesity who engaged in the RT, AT, and CT interventions demonstrated increased muscle mass and reduced total fat mass and VFA compared with those without training. The muscle strength performance and serum IGF-1 level in trained groups, especially in the RT group, were superior to the control group. © 2017, Copyright the Authors Journal compilation © 2017, The American Geriatrics Society.

Gender differences in the circadian variations in muscle strength assessed with and without superimposed electrical twitches.

PubMed

Giacomoni, Magali; Edwards, Ben; Bambaeichi, Effat

The circadian rhythm in muscle strength was analysed in 12 males (28 +/- 4 years, 79.6 +/- 12.3 kg, 1.80 +/- 0.05 m) and eight females (28 +/- 4 years, 60.3 +/- 5.5 kg, 1.61 +/- 0.08 m). After two familiarization sessions, participants were tested at six different times of the day (02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 hours), the order of which was randomly assigned over 3-4 days. Rectal temperature (T(rec)) was measured over 30 min before each test. Peak isokinetic torques (PT) of knee extensors and flexors were then measured at 1.05 rad s(-1) and 3.14 rad s(-1) through a 90 degrees range of motion. Maximal isometric voluntary contraction (MVC) of knee extensors and flexors was measured at 60 degrees of knee flexion and the MVC of knee extensors was also assessed with superimposed electrical twitches (50 Hz, 250 V, 200 mus pulse width) in order to control for motivational effects. Three trials were performed in each condition, separated by 3 min recovery, and the highest values were retained for subsequent analyses. A significant circadian rhythm was observed for T(rec) in both males and females (acrophase, Phi, 17:29 and 16:40 hours; mesor, Me, 37.0 and 36.8 degrees C; amplitude, A, 0.28 and 0.33 degrees C for males and females, respectively). The mesor of T(rec) was higher in males than in females (p < 0.05). Significant circadian rhythms were observed for knee extensor PT at 3.14 rad s(-1) in males (Phi, 17:06 hours; Me, 178.2 N m; A, 4.7 N m) and for knee extensor PT at 1.05 rad s(-1) in females (Phi, 15:35 hours; Me, 128.7 N m; A, 3.7 N m). In males, the MVC of knee extensors demonstrated a significant circadian rhythm, but only when electrical twitches were superimposed (Phi, 16:17 h; Me, 302.1 N m; A, 13.6 N m). Acrophases of all indices of muscle strength were not statistically different between the two groups and were located in the afternoon (12:47 < Phi < 17:16 hours). The amplitude (percentage of mesor) of extensors MVC (electrically stimulated) was higher in males (6.4%) than in females (4.2%; p < 0.05). Significant circadian rhythms were not consistently observed for all indices of muscle strength whatever the gender. Our group of female subjects tended to show lower circadian amplitudes than the males. In males, maximal voluntary contraction of electrically stimulated muscles followed a circadian curve, which was not significant without the superimposed twitches. These results suggest that motivation could have a masking effect on the circadian rhythm in muscle performance and strengthen the view that peripheral factors are implicated in this rhythm.

Reduced Electromyographic Fatigue Threshold after Performing a Cognitive Fatiguing Task.

PubMed

Ferris, Justine R; Tomlinson, Mary A; Ward, Tayler N; Pepin, Marie E; Malek, Moh H

2018-02-22

Cognitive fatigue tasks performed prior to exercise may reduce exercise capacity. The electromyographic fatigue threshold (EMGFT) is the highest exercise intensity that can be maintained without significant increase in the EMG amplitude versus time relationship. To date, no studies have examined the effect of cognitive fatigue on the estimation of the EMGFT. The purpose of this study, therefore, was to determine whether or not cognitive fatigue prior to performing exercise reduces the estimated EMGFT. Eight healthy college-aged men were recruited from a university student population and visited the laboratory on multiple occasions. In a randomized order, subjects performed either the cognitive fatigue task (AX Continuous Performance Test; AX-CPT) for 60 min on one visit (experimental condition) or watched a video on trains for 60 min on the other visit (control condition). After each condition, subjects performed the incremental single-leg knee-extensor ergometry test while the EMG amplitude was recorded from the rectus femoris muscle and heart rate was monitored throughout. Thereafter, the EMGFT was calculated for each participant for each visit and compared using paired samples t-test. For exercise outcomes, there were no significant mean differences for maximal power output between the two conditions (control: 51 ± 5 vs. fatigue: 50 ± 3 W), but a significant decrease in EMGFT between the two conditions (control: 31 ± 3 vs. fatigue: 24 ± 2 W; p = 0.013). Moreover, maximal heart rate was significantly different between the two conditions (control: 151 ± 5 vs. fatigue: 132 ± 6; p = 0.027). These results suggest that performing the cognitive fatiguing task reduces the EMGFT with a corresponding reduction in maximal heart rate response.

Relation between functional mobility and dynapenia in institutionalized frail elderly

PubMed Central

Soares, Antonio Vinicius; Marcelino, Elessandra; Maia, Késsia Cristina; Borges, Noé Gomes

2017-01-01

ABSTRACT Objective To investigate the relation between functional mobility and dynapenia in institutionalized frail elderly. Methods A descriptive, correlational study involving 26 institutionalized elderly men and women, mean age 82.3±6 years. The instruments employed were the Mini Mental State Examination, the Geriatric Depression Scale, the International Physical Activity Questionnaire, the Timed Up and Go test, a handgrip dynamometer and a portable dynamometer for large muscle groups (shoulder, elbow and hip flexors, knee extensors and ankle dorsiflexors). Results Significant negative correlation between functional mobility levels assessed by the Timed Up and Go test and dynapenia was observed in all muscle groups evaluated, particularly in knee extensors (r -0.65). Conclusion A significant negative correlation between muscle strength, particularly knee extensor strength, and functional mobility was found in institutionalized elderly. Data presented indicate that the higher the muscle strength, the shorter the execution time, and this could demonstrate better performance in this functional mobility test. PMID:29091148

Changes of pedaling technique and muscle coordination during an exhaustive exercise.

PubMed

Dorel, Sylvain; Drouet, Jean-Marc; Couturier, Antoine; Champoux, Yvan; Hug, François

2009-06-01

Alterations of the mechanical patterns during an exhaustive pedaling exercise have been previously shown. We designed the present study to test the hypothesis that these alterations in the biomechanics of pedaling, which occur during exhaustive exercise, are linked to changes in the activity patterns of lower limb muscles. Ten well-trained cyclists were tested during a limited time to exhaustion, performing 80% of maximal power tolerated. Pedal force components were measured continuously using instrumented pedals and were synchronized with surface EMG signals measured in 10 lower limb muscles. The results confirmed most of the alterations of the mechanical patterns previously described in the literature. The magnitude of the root mean squared of the EMG during the complete cycle (RMScycle) for tibialis anterior and gastrocnemius medialis decreased significantly (P < 0.05) from 85% and 75% of Tlim, respectively. A higher RMScycle was obtained for gluteus maximus (P < 0.01) and biceps femoris (P < 0.05) from 75% of Tlim. The k values that resulted from the cross-correlation technique indicated that the activities of six muscles (gastrocnemius medialis, gastrocnemius lateralis, tibialis anterior, vastus lateralis, vastus medialis, and rectus femoris) were shifted forward in the cycle at the end of the exercise. The large increases in activity for gluteus maximus and biceps femoris, which are in accordance with the increase in force production during the propulsive phase, could be considered as instinctive coordination strategies that compensate for potential fatigue and loss of force of the knee extensors (i.e., vastus lateralis and vastus medialis) by a higher moment of the hip extensors.

Influence of exercise intensity on skeletal muscle blood flow, O2 extraction and O2 uptake on-kinetics

PubMed Central

Jones, Andrew M; Krustrup, Peter; Wilkerson, Daryl P; Berger, Nicolas J; Calbet, José A; Bangsbo, Jens

2012-01-01

Following the start of low-intensity exercise in healthy humans, it has been established that the kinetics of skeletal muscle O2 delivery is faster than, and does not limit, the kinetics of muscle O2 uptake (). Direct data are lacking, however, on the question of whether O2 delivery might limit kinetics during high-intensity exercise. Using multiple exercise transitions to enhance confidence in parameter estimation, we therefore investigated the kinetics of, and inter-relationships between, muscle blood flow (), a– difference and following the onset of low-intensity (LI) and high-intensity (HI) exercise. Seven healthy males completed four 6 min bouts of LI and four 6 min bouts of HI single-legged knee-extension exercise. Blood was frequently drawn from the femoral artery and vein during exercise and , a– difference and were calculated and subsequently modelled using non-linear regression techniques. For LI, the fundamental component mean response time (MRTp) for kinetics was significantly shorter than kinetics (mean ± SEM, 18 ± 4 vs. 30 ± 4 s; P < 0.05), whereas for HI, the MRTp for and was not significantly different (27 ± 5 vs. 29 ± 4 s, respectively). There was no difference in the MRTp for either or between the two exercise intensities; however, the MRTp for a– difference was significantly shorter for HI compared with LI (17 ± 3 vs. 28 ± 4 s; P < 0.05). Excess O2, i.e. oxygen not taken up (×), was significantly elevated within the first 5 s of exercise and remained unaltered thereafter, with no differences between LI and HI. These results indicate that bulk O2 delivery does not limit kinetics following the onset of LI or HI knee-extension exercise. PMID:22711961

Use of Low Level of Continuous Heat as an Adjunct to Physical Therapy Improves Knee Pain Recovery and the Compliance for Home Exercise in Patients With Chronic Knee Pain: A Randomized Controlled Trial.

PubMed

Petrofsky, Jerrold S; Laymon, Michael S; Alshammari, Faris S; Lee, Haneul

2016-11-01

Petrofsky, JS, Laymon, MS, Alshammari, FS, and Lee, H. Use of low level of continuous heat as an adjunct to physical therapy improves knee pain recovery and the compliance for home exercise in patients with chronic knee pain: a randomized controlled trial. J Strength Cond Res 30(11): 3107-3115, 2016-This study examined if the use of low level continuous heat (LLCH) wraps at home between physical therapy sessions at a clinic resulted in better therapy outcomes in patients with chronic knee pain. Fifty individuals with chronic nonspecific knee pain was randomly allocated to 2 groups: the LLCH group and the placebo group. All subjects underwent 1 hour of conventional physical therapy twice per week for 2 weeks at the outpatient clinic and they were asked to accomplish 1 hour of therapeutic exercise at home each day between sessions. The LLCH group applied LLCH knee wraps for 6 hours at home before home exercise while placebo group took a placebo ibuprofen. (This was done since placebo heat is impossible to use since subjects would notice that the wraps were cold) Before, during, and after intervention, pain intensity, active range of motion of the knee (AROM), knee strength, and home exercise compliance were measured. The LLCH group showed pain attenuation after 2 weeks of therapy sessions (p ≤ 0.05). AROM and strength of the knee significantly improved over time compared to the placebo group. Home exercise compliance was significantly higher in the LLCH group than placebo group (p ≤ 0.05). These results indicated that the use of LLCH as an adjunct to conventional physical therapy for chronic knee pain significantly improved pain attenuation and recovery of strength and movement in patients with chronic knee pain.

Muscular activity and torque of the foot dorsiflexor muscles during decremental isometric test: A cross-sectional study.

PubMed

Ruiz-Muñoz, Maria; González-Sánchez, Manuel; Martín-Martín, Jaime; Cuesta-Vargas, Antonio I

2017-06-01

To analyse the torque variation level that could be explained by the muscle activation (EMG) amplitude of the three major foot dorsiflexor muscles (tibialis anterior (TA), extensor digitorum longus (EDL), extensor hallucis longus (EHL)) during isometric foot dorsiflexion at different intensities. In a cross-sectional study, forty-one subjects performed foot dorsiflexion at 100%, 75%, 50% and 25% of maximal voluntary contractions (MVC) with the hip and knee flexed 90° and the ankle in neutral position (90° between leg and foot). Three foot dorsiflexions were performed for each intensity. Outcome variables were: maximum (100% MVC) and relative torque (75%, 50%, 25% MVC), maximum and relative EMG amplitude. A linear regression analysis was calculated for each intensity of the isometric foot dorsiflexion. The degree of torque variation (dependent variable) from the independent variables explain (EMG amplitude of the three major foot dorsiflexor muscles) the increases when the foot dorsiflexion intensity is increased, with values of R 2 that range from 0.194 (during 25% MVC) to 0.753 (during 100% MVC). The reliability of the outcome variables was excellent. The EMG amplitude of the three main foot dorsiflexors exhibited more variance in the dependent variable (torque) when foot dorsiflexion intensity increases. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electromyographic activity of the trunk extensor muscles: effect of varying hip position and lumbar posture during Roman chair exercise.

PubMed

Mayer, John M; Verna, Joe L; Manini, Todd M; Mooney, Vert; Graves, James E

2002-11-01

To evaluate the effect of hip position and lumbar posture on the surface electromyographic activity of the trunk extensors during Roman chair exercise. Descriptive, repeated measures. University-based musculoskeletal research laboratory. Twelve healthy volunteers (7 men, 5 women; age range, 18-35y) without a history of low back pain were recruited from a university setting. Not applicable. Surface electromyographic activity was recorded from the lumbar extensor, gluteal, and hamstring musculature during dynamic Roman chair exercise. For each muscle group, electromyographic activity (mV/rep) was compared among exercises with internal hip rotation and external hip rotation and among exercises by using a typical lumbar posture (nonbiphasic) and a posture that accentuated lumbar lordosis (biphasic). For the lumbar extensors, electromyographic activity during exercise was 18% greater with internal hip rotation than external hip rotation (P< or =.05) and was 25% greater with a biphasic posture than with a nonbiphasic posture (P< or =.05). For the gluteals and hamstrings, there was no difference in electromyographic activity between internal and external hip rotation or between biphasic and nonbiphasic postures (P >.05). The level of recruitment of the lumbar extensors can be modified during Roman chair exercise by altering hip position and lumbar posture. Clinicians can use these data to develop progressive exercise protocols for the lumbar extensors with a variety of resistance levels without the need for complex equipment. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Core stability training on lower limb balance strength.

PubMed

Dello Iacono, Antonio; Padulo, Johnny; Ayalon, Moshe

2016-01-01

This study aimed to assess the effects of core stability training on lower limbs' muscular asymmetries and imbalances in team sport. Twenty footballers were divided into two groups, either core stability or control group. Before each daily practice, core stability group (n = 10) performed a core stability training programme, while control group (n = 10) did a standard warm-up. The effects of the core stability training programme were assessed by performing isokinetic tests and single-leg countermovement jumps. Significant improvement was found for knee extensors peak torque at 3.14 rad · s(-1) (14%; P < 0.05), knee flexors peak torque at 1.05 and 3.14 rad · s(-1) (19% and 22% with P < 0.01 and P < 0.01, respectively) and peak torque flexors/extensors ratios at 1.05 and 3.14 rad · s(-1) (7.7% and 8.5% with P < 0.05 and P < 0.05, respectively) only in the core stability group. The jump tests showed a significant reduction in the strength asymmetries in core stability group (-71.4%; P = 0.02) while a concurrent increase was seen in the control group (33.3%; P < 0.05). This study provides practical evidence in combining core exercises for optimal lower limbs strength balance development in young soccer players.

Recovery After High-Intensity Intermittent Exercise in Elite Soccer Players Using VEINOPLUS Sport Technology for Blood-Flow Stimulation

PubMed Central

Bieuzen, François; Pournot, Hervé; Roulland, Rémy; Hausswirth, Christophe

2012-01-01

Context Electric muscle stimulation has been suggested to enhance recovery after exhaustive exercise by inducing an increase in blood flow to the stimulated area. Previous studies have failed to support this hypothesis. We hypothesized that the lack of effect shown in previous studies could be attributed to the technique or device used. Objective To investigate the effectiveness of a recovery intervention using an electric blood-flow stimulator on anaerobic performance and muscle damage in professional soccer players after intermittent, exhaustive exercise. Design Randomized controlled clinical trial. Setting National Institute of Sport, Expertise, and Performance (INSEP). Patients or Other Participants Twenty-six healthy professional male soccer players. Intervention(s) The athletes performed an intermittent fatiguing exercise followed by a 1-hour recovery period, either passive or using an electric blood-flow stimulator (VEINOPLUS). Participants were randomly assigned to a group before the experiment started. Main Outcome Measures(s) Performances during a 30-second all-out exercise test, maximal vertical countermovement jump, and maximal voluntary contraction of the knee extensor muscles were measured at rest, immediately after the exercise, and 1 hour and 24 hours later. Muscle enzymes indicating muscle damage (creatine kinase, lactate dehydrogenase) and hematologic profiles were analyzed before and 1 hour and 24 hours after the intermittent fatigue exercise. Results The electric-stimulation group had better 30-second all-out performances at 1 hour after exercise (P = .03) in comparison with the passive-recovery group. However, no differences were observed in muscle damage markers, maximal vertical countermovement jump, or maximal voluntary contraction between groups (P > .05). Conclusions Compared with passive recovery, electric stimulation using this blood-flow stimulator improved anaerobic performance at 1 hour postintervention. No changes in muscle damage markers or maximal voluntary contraction were detected. These responses may be considered beneficial for athletes engaged in sports with successive rounds interspersed with short, passive recovery periods. PMID:23068586

Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners.

PubMed

Kuhman, Daniel; Melcher, Daniel; Paquette, Max R

2016-01-01

The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6 min mile(-1)) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations.

Influence of patellofemoral bracing on pain, knee extensor torque, and gait function in females with patellofemoral pain.

PubMed

Powers, Christopher M; Doubleday, Kathryn L; Escudero, Carina

2008-01-01

Our purpose was to evaluate the effects of a patellofemoral brace on pain response, knee extensor torque production, and gait function in females with patellofemoral pain (PFP). Sixteen females between the ages of 14 and 46 with diagnosis of PFP participated. Knee extensor torque was measured by using a LIDO isokinetic dynamometer. Pain levels were documented by using the Visual Analog Pain Scale. Stride characteristics during the conditions of free walk, fast walk, ascend stairs, descend stairs, ascend ramp, and descend ramp were obtained with a stride analyzer unit. EMG activity of the vasti musculature was recorded by using indwelling, bipolar, wire electrodes. Knee joint motion was assessed by using a VICON motion analysis system. All testing was performed with and without the Bauerfeind Genutrain P3 patellofemoral brace. There were no significant differences in torque production, pain levels, and stride characteristics between braced and non-braced trials. In addition, there were no significant differences in mean vasti EMG between braced and non-braced trials. When averaged across all conditions, a small but statistically significant increase in knee flexion was found during the braced trials. Although the current study did not find significant improvements in the clinical measures evaluated, 8 of the 16 subjects did experience a decrease in knee pain. This finding suggests that certain patients with PFP may respond favorably to bracing, and criteria must be established to determine which patients would best benefit from such an intervention.

Gains in flexibility related to measures of muscular performance: impact of flexibility on muscular performance.

PubMed

Ferreira, Gustavo Nunes Tasca; Teixeira-Salmela, Luci Fuscaldi; Guimarães, Cristiano Queiroz

2007-07-01

Studies that investigated possible correlations between flexibility and muscular performance are scarce in the literature. Therefore, the purpose of this study was to investigate the impact of a program of static stretching on the flexibility of the hamstrings and on muscular performance of the knee flexors and extensors. Pre-post experimental design. University laboratory. Thirty subjects aged 22.8 +/- 4.9 years with bilaterally shortened hamstrings. Using a protocol that has been previously described, the intervention consisted of 30 sessions of static stretching, performed bilaterally five times a week for 6 weeks. Measures of knee range of motion and isokinetic muscular performance (peak torque, angle of peak torque, and work) of knee flexors and extensors at speeds of 60 and 300 degrees/s. After intervention, significant gains in measures of flexibility (P < 0.0001) were observed, with an average gain of the knee-extension angle of 12.6 degrees, ranging from -1.2 to 30.7 degrees. In addition, we found significant increases in the following parameters of muscular performance: angle of peak torque of hamstrings at 60 and 300 degrees/s (P < 0.0001 and 0.018) and for work at 60 and 300 degrees/s for knee flexors (P = 0.012 and 0.005) and for knee extensors (P < 0.0001). The intervention resulted in gains in measures of flexibility, and these gains had a positive impact on some parameters of muscular performance.

Effect of sex and fatigue on muscle stiffness and musculoarticular stiffness of the knee joint in a young active population.

PubMed

Wang, Dan; De Vito, Giuseppe; Ditroilo, Massimiliano; Delahunt, Eamonn

2017-08-01

The purpose of this study was to investigate the influence of sex and fatigue on knee extensor peak torque (PT), muscle stiffness (MS) of the vastus lateralis (VL) and knee joint musculoarticular stiffness (MAS) in young adults. Twenty-two male and 22 female recreational athletes participated. Males were characterised by higher relaxed [pre-: males 364.43 (52.00) N · m -1 , females 270.27 (37.25) N · m -1 ; post-: males 446.75 (83.27) N · m -1 , females 307.39 (38.58) N · m -1 ] and contracted [pre-: males 495.07 (71.04) N · m -1 , females 332.34 (85.42) N · m -1 ; post-: males 546.37 (90.74) N · m -1 , females 349.21 (85.55) N · m -1 ] MS of the VL, and knee joint MAS [pre-: males 1450.11 (507.98) N · m -1 , females 1027.99 (227.33) N · m -1 ; post-: males 1345.81 (404.90) N · m -1 , females 952.78 (192.38) N · m -1 ] than females pre- and post-fatigue. A similar finding was observed in pre-fatigue normalised knee extensor PT [pre-: males 2.77 (0.42) N · m kg -1 , females 2.41 (0.40) N · m kg -1 , post-: males 2.53 (0.54) N · m kg -1 , females 2.26 (0.44) N · m kg -1 ]. After the fatigue protocol, normalised knee extensor PT and knee joint MAS decreased, whilst relaxed and contracted MS of the VL increased in both sexes. These observed differences may contribute to the higher risk of knee injury in females and following the onset of fatigue.

Fatigue associated with prolonged graded running.

PubMed

Giandolini, Marlene; Vernillo, Gianluca; Samozino, Pierre; Horvais, Nicolas; Edwards, W Brent; Morin, Jean-Benoît; Millet, Guillaume Y

2016-10-01

Scientific experiments on running mainly consider level running. However, the magnitude and etiology of fatigue depend on the exercise under consideration, particularly the predominant type of contraction, which differs between level, uphill, and downhill running. The purpose of this review is to comprehensively summarize the neurophysiological and biomechanical changes due to fatigue in graded running. When comparing prolonged hilly running (i.e., a combination of uphill and downhill running) to level running, it is found that (1) the general shape of the neuromuscular fatigue-exercise duration curve as well as the etiology of fatigue in knee extensor and plantar flexor muscles are similar and (2) the biomechanical consequences are also relatively comparable, suggesting that duration rather than elevation changes affects neuromuscular function and running patterns. However, 'pure' uphill or downhill running has several fatigue-related intrinsic features compared with the level running. Downhill running induces severe lower limb tissue damage, indirectly evidenced by massive increases in plasma creatine kinase/myoglobin concentration or inflammatory markers. In addition, low-frequency fatigue (i.e., excitation-contraction coupling failure) is systematically observed after downhill running, although it has also been found in high-intensity uphill running for different reasons. Indeed, low-frequency fatigue in downhill running is attributed to mechanical stress at the interface sarcoplasmic reticulum/T-tubule, while the inorganic phosphate accumulation probably plays a central role in intense uphill running. Other fatigue-related specificities of graded running such as strategies to minimize the deleterious effects of downhill running on muscle function, the difference of energy cost versus heat storage or muscle activity changes in downhill, level, and uphill running are also discussed.

Contribution of knee flexor and extensor strength on sex-specific energy absorption and torsional joint stiffness during drop jumping.

PubMed

Schmitz, Randy J; Shultz, Sandra J

2010-01-01

Lower extremity injury often occurs during abrupt deceleration when attempting to change the body's direction. Although sex-specific biomechanics have been implicated in the greater risk of acute knee injury in women than in men, it is unknown if sex differences in thigh strength affect sex-specific energy absorption and torsional joint stiffness patterns. To determine sex differences in energy absorption patterns and joint stiffnesses of the lower extremity during a drop jump and to determine if these sex differences were predicted by knee extensor and flexor strength. Cross-sectional study. Laboratory environment. Recreationally active, college-aged students (41 women: age  =  22.1 ± 2.9 years, height  =  1.63 ± 0.07 m, mass  =  59.3 ± 8.0 kg; 40 men: age  =  22.4 ± 2.8 years, height  =  1.77 ± 0.1 m, mass  =  80.9 ± 14.1 kg). Participants performed knee flexor and extensor maximal voluntary isometric contractions followed by double-leg drop-jump landings. Lower extremity joint energetics (J × N(-1) × m(-1)) and torsional joint stiffnesses (Nm × N(-1) × m(-1) × degrees(-1)) were calculated for the hip, knee, and ankle during the initial landing phase. Body weight was measured in newtons and height was measured in meters. Sex comparisons were made and sex-specific regressions determined if thigh muscle strength (Nm/kg) predicted sagittal-plane landing energetics and stiffnesses. Women absorbed 69% more knee energy and had 36% less hip torsional stiffness than men. In women, greater knee extensor strength predicted greater knee energy absorption (R(2)  =  0.11, P  =  .04), and greater knee flexor strength predicted greater hip torsional stiffness (R(2)  =  0.12, P  =  .03). Sex-specific biomechanics during the deceleration phase of a drop jump revealed that women used a strategy to attempt to decrease system stiffness. Additionally, only female strength values were predictive of landing energetics and stiffnesses. These findings collectively demonstrated that the task may have been more difficult for women, resulting in a different movement strategy among those with different levels of thigh strength to safely complete the task. Future researchers should look at other predictive factors of observed sex differences.

Gouty involvement of the patella and extensor mechanism of the knee mimicking aggressive neoplasm. A case series.

PubMed

Kester, Christopher; Wallace, Matthew T; Jelinek, James; Aboulafia, Albert

2018-06-01

Gout is a common inflammatory crystal deposition disease that occurs in many joints throughout the body. Active gout is most often associated with painful synovitis causing searing joint pains, but gout can also produce large masses of space-occupying deposits called tophi. Tophi are most frequently seen in juxta-articular locations with or without bony erosion and are often misdiagnosed as degenerative joint disease. Soft tissue deposits and tendon involvement are also known manifestations of gout, but can present with indeterminate and alarming findings on imaging. We present three cases of tophaceous gout mimicking aggressive neoplasms in the extensor mechanism of the knee. All cases presented as extensor tendon masses eroding into the patella, with imaging findings initially concerning for primary musculoskeletal malignancy.

Exercise Training in Treatment and Rehabilitation of Hip Osteoarthritis: A 12-Week Pilot Trial

PubMed Central

Patil, Radhika; Karinkanta, Saija; Tokola, Kari; Kannus, Pekka

2017-01-01

Introduction. Osteoarthritis (OA) of the hip is one of the major causes of pain and disability in the older population. Although exercise is an effective treatment for knee OA, there is lack of evidence regarding hip OA. The aim of this trial was to test the safety and feasibility of a specifically designed exercise program in relieving hip pain and improving function in hip OA participants and to evaluate various methods to measure changes in their physical functioning. Materials and Methods. 13 women aged ≥ 65 years with hip OA were recruited in this 12-week pilot study. Results. Pain declined significantly over 30% from baseline, and joint function and health-related quality of life improved slightly. Objective assessment of physical functioning showed statistically significant improvement in the maximal isometric leg extensor strength by 20% and in the hip extension range of motion by 30%. Conclusions. The exercise program was found to be safe and feasible. The present evidence indicates that the exercise program is effective in the short term. However, adequate powered RCTs are needed to determine effects of long-term exercise therapy on pain and progression of hip OA. PMID:28116214

Evaluation of the Combined Application of Neuromuscular Electrical Stimulation and Volitional Contractions on Thigh Muscle Strength, Knee Pain and Physical Performance in Women at Risk for Knee Osteoarthritis: A Randomized Controlled Trial.

PubMed

Rabe, Kaitlin G; Matsuse, Hiroo; Jackson, Anthony; Segal, Neil A

2018-05-28

Knee osteoarthritis (OA) is a leading cause of disability that is associated with quadriceps weakness. However, strengthening in people with or with risk factors for knee OA can be poorly tolerated. To assess the efficacy of a twelve-week low-load exercise program, using a hybrid training system (HTS) that utilizes the combination of neuromuscular electrical stimulation and volitional contractions, for improving thigh muscle strength, knee pain and physical performance in women with or with risk factors for knee OA. Randomized, single-blind, controlled trial SETTING: Exercise training laboratory PARTICIPANTS: Forty-two women, age 44-85 years, with risk factors for knee OA INTERVENTIONS: Participants randomized to 12 weeks of biweekly low-load resistance training either with HTS or on an isokinetic dynamometer (control). Maximum isokinetic knee extensor torque. Secondary measures included: maximum isokinetic knee flexor torque, knee pain (KOOS), and timed 20-meter walk and chair-stand tests. HTS and control both resulted in muscle strengthening, reduced knee pain and improved physical performance. HTS group quadriceps and hamstring strength increased by 0.06±0.04 Nm/kg (p>.05) and 0.05±0.02 Nm/kg (p=.02), respectively. Control group quadriceps and hamstring strength increased by 0.03±0.04 Nm/kg (p>.05) and 0.06±0.02 Nm/kg (p=.009), respectively. Knee pain improved by 11.9±11.5 points (p<.001) for the HTS group and 14.1±15.4 points (p=.001) for the control group. 20-meter walk time decreased by 1.60±2.04 seconds (p=.005) and 0.95±1.2 seconds (p=.004), and chair stand time decreased by 4.8±10.0 seconds (p>.05) and 1.9±4.7 seconds (p>.05) in the HTS and control groups, respectively. These results did not differ statistically between HTS and control groups. These results suggest HTS is effective for improving pain and physical performance in women with risk factors for knee OA. However, HTS does not appear to be superior to low-load resistance training for improving muscle strength, pain or physical function. Copyright © 2018 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

The association between antagonist hamstring coactivation and episodes of knee joint shifting and buckling

PubMed Central

Segal, N.A.; Nevitt, M.C.; Welborn, R.D.; Nguyen, U.-S.D.T.; Niu, J.; Lewis, C.E.; Felson, D.T.; Frey-Law, L.

2016-01-01

SUMMARY Objective Hamstring coactivation during quadriceps activation is necessary to counteract the quadriceps pull on the tibia, but coactivation can be elevated with symptomatic knee osteoarthritis (OA). To guide rehabilitation to attenuate risk for mobility limitations and falls, this study evaluated whether higher antagonistic open kinetic chain hamstring coactivation is associated with knee joint buckling (sudden loss of support) and shifting (a sensation that the knee might give way). Design At baseline, median hamstring coactivation was assessed during maximal isokinetic knee extensor strength testing and at baseline and 24-month follow-up, knee buckling and shifting was self-reported. Associations between tertiles of co-activation and knee (1) buckling, (2) shifting and (3) either buckling or shifting were assessed using logistic regression, adjusted for age, sex, knee OA and pain. Results 1826 participants (1089 women) were included. Mean ± SD age was 61.7 ± 7.7 years, BMI was 30.3 ± 5.5 kg/m2 and 38.2% of knees had OA. There were no consistent statistically significant associations between hamstring coactivation and ipsilateral prevalent or incident buckling or the combination of buckling and shifting. The odds ratios for incident shifting in the highest in comparison with the lowest tertile of coactivation had similar magnitudes in the combined and medial hamstrings, but only reached statistical significance for lateral hamstring coactivation, OR(95%CI) 1.53 (0.99, 2.36). Conclusions Hamstring coactivation during an open kinetic chain quadriceps exercise was not consistently associated with prevalent or incident self-reported knee buckling or shifting in older adults with or at risk for knee OA. PMID:25765501

Hip and trunk muscles activity during nordic hamstring exercise.

PubMed

Narouei, Shideh; Imai, Atsushi; Akuzawa, Hiroshi; Hasebe, Kiyotaka; Kaneoka, Koji

2018-04-01

The nordic hamstring exercise (NHE) is a dynamic lengthening hamstring exercise that requires trunk and hip muscles activation. Thigh muscles activation, specifically hamstring/quadriceps contractions has been previously examined during NHE. Trunk and hip muscles activity have not been enough studied. The aim of this study was to analyze of hip and trunk muscles activity during NHE. Surface electromyography (EMG) and kinematic data were collected during NHE. Ten healthy men with the age range of 21-36 years performed two sets of two repetitions with downward and upward motions each of NHE. EMG activity of fifteen trunk and hip muscles and knee kinematic data were collected. Muscle activity levels were calculated through repeated measure analysis of variance in downward and upward motions, through Paired t -test between downward and upward motions and gluteus maximus to erector spine activity ratio (Gmax/ES ratio) using Pearson correlation analyses were evaluated. Semitendinosus and biceps femoris muscles activity levels were the greatest in both motions and back extensors and internal oblique muscles activity were greater than other muscles ( P <0.05). The decreased Gmax/ES ratio was significantly related to peak knee extension angle in downward ( r =0.687) and upward motions ( r =0.753) ( P <0.05). These findings indicate the importance of synergistic muscles and trunk muscles coactivation in eccentric and concentric hamstrings contractions. It could be important for early assessment of subjects with hamstring injury risk.

Hip and trunk muscles activity during nordic hamstring exercise

PubMed Central

Narouei, Shideh; Imai, Atsushi; Akuzawa, Hiroshi; Hasebe, Kiyotaka; Kaneoka, Koji

2018-01-01

The nordic hamstring exercise (NHE) is a dynamic lengthening hamstring exercise that requires trunk and hip muscles activation. Thigh muscles activation, specifically hamstring/quadriceps contractions has been previously examined during NHE. Trunk and hip muscles activity have not been enough studied. The aim of this study was to analyze of hip and trunk muscles activity during NHE. Surface electromyography (EMG) and kinematic data were collected during NHE. Ten healthy men with the age range of 21–36 years performed two sets of two repetitions with downward and upward motions each of NHE. EMG activity of fifteen trunk and hip muscles and knee kinematic data were collected. Muscle activity levels were calculated through repeated measure analysis of variance in downward and upward motions, through Paired t-test between downward and upward motions and gluteus maximus to erector spine activity ratio (Gmax/ES ratio) using Pearson correlation analyses were evaluated. Semitendinosus and biceps femoris muscles activity levels were the greatest in both motions and back extensors and internal oblique muscles activity were greater than other muscles (P<0.05). The decreased Gmax/ES ratio was significantly related to peak knee extension angle in downward (r=0.687) and upward motions (r=0.753) (P<0.05). These findings indicate the importance of synergistic muscles and trunk muscles coactivation in eccentric and concentric hamstrings contractions. It could be important for early assessment of subjects with hamstring injury risk. PMID:29740557

Alterations in neuromuscular function in girls with generalized joint hypermobility.

PubMed

Jensen, Bente Rona; Sandfeld, Jesper; Melcher, Pia Sandfeld; Johansen, Katrine Lyders; Hendriksen, Peter; Juul-Kristensen, Birgit

2016-10-03

Generalized Joint Hypermobility (GJH) is associated with increased risk of musculoskeletal joint pain. We investigated neuromuscular performance and muscle activation strategy. Girls with GJH and non-GJH (NGJH) performed isometric knee flexions (90°,110°,130°), and extensions (90°) at 20 % Maximum Voluntary Contraction, and explosive isometric knee flexions while sitting. EMG was recorded from knee flexor and extensor muscles. Early rate of torque development was 53 % faster for GJH. Reduced hamstring muscle activation in girls with GJH was found while knee extensor and calf muscle activation did not differ between groups. Flexion-extension and medial-lateral co-activation ratio during flexions were higher for girls with GJH than NGJH girls. Girls with GJH had higher capacity to rapidly generate force than NGJH girls which may reflect motor adaptation to compensate for hypermobility. Higher medial muscle activation indicated higher levels of medial knee joint compression in girls with GJH. Increased flexion-extension co-activation ratios in GJH were explained by decreased agonist drive to the hamstrings.

Resveratrol Enhances Exercise-Induced Cellular and Functional Adaptations of Skeletal Muscle in Older Men and Women.

PubMed

Alway, Stephen E; McCrory, Jean L; Kearcher, Kalen; Vickers, Austen; Frear, Benjamin; Gilleland, Diana L; Bonner, Daniel E; Thomas, James M; Donley, David A; Lively, Mathew W; Mohamed, Junaith S

2017-11-09

Older men (n = 12) and women (n = 18) 65-80 years of age completed 12 weeks of exercise and took either a placebo or resveratrol (RSV) (500 mg/d) to test the hypothesis that RSV treatment combined with exercise would increase mitochondrial density, muscle fatigue resistance, and cardiovascular function more than exercise alone. Contrary to our hypothesis, aerobic and resistance exercise coupled with RSV treatment did not reduce cardiovascular risk further than exercise alone. However, exercise added to RSV treatment improved the indices of mitochondrial density, and muscle fatigue resistance more than placebo and exercise treatments. In addition, subjects that were treated with RSV had an increase in knee extensor muscle peak torque (8%), average peak torque (14%), and power (14%) after training, whereas exercise did not increase these parameters in the placebo-treated older subjects. Furthermore, exercise combined with RSV significantly improved mean fiber area and total myonuclei by 45.3% and 20%, respectively, in muscle fibers from the vastus lateralis of older subjects. Together, these data indicate a novel anabolic role of RSV in exercise-induced adaptations of older persons and this suggests that RSV combined with exercise might provide a better approach for reversing sarcopenia than exercise alone. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Relation between the Disability of the Arm, Shoulder and Hand Score and Muscle Strength in Post-Cardiac Surgery Patients.

PubMed

Izawa, Kazuhiro P; Kasahara, Yusuke; Hiraki, Koji; Hirano, Yasuyuki; Watanabe, Satoshi

2017-11-27

Background: The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire is a valid and reliable patient-reported outcome measure. DASH can be assessed by self-reported upper extremity disability and symptoms. We aimed to examine the relationship between the physiological outcome of muscle strength and the DASH score after cardiac surgery. Methods: This cross-sectional study assessed 50 consecutive cardiac patients that were undergoing cardiac surgery. Physiological outcomes of handgrip strength and knee extensor muscle strength and the DASH score were measured at one month after cardiac surgery and were assessed. Results were analyzed using Spearman correlation coefficients. Results: The final analysis comprised 43 patients (men: 32, women: 11; age: 62.1 ± 9.1 years; body mass index: 22.1 ± 4.7 kg/m²; left ventricular ejection fraction: 53.5 ± 13.7%). Respective handgrip strength, knee extensor muscle strength, and DASH score were 27.4 ± 8.3 kgf, 1.6 ± 0.4 Nm/kg, and 13.3 ± 12.3, respectively. The DASH score correlated negatively with handgrip strength ( r = -0.38, p = 0.01) and with knee extensor muscle strength ( r = -0.32, p = 0.04). Conclusion: Physiological outcomes of both handgrip strength and knee extensor muscle strength correlated negatively with the DASH score. The DASH score appears to be a valuable tool with which to assess cardiac patients with poor physiological outcomes, particularly handgrip strength as a measure of upper extremity function, which is probably easier to follow over time than lower extremity function after patients complete cardiac rehabilitation.

Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques

PubMed Central

Suzuki, Takahito; Kinugasa, Ryuta; Fukashiro, Senshi

2017-01-01

Behavioral evidence has suggested that a small number of muscle synergies may be responsible for activating a variety of muscles. Nevertheless, such dimensionality reduction may also be explained using the perspective of alternative hypotheses, such as predictions based on linear combinations of joint torques multiplied by corresponding coefficients. To compare the explanatory capacity of these hypotheses for describing muscle activation, we enrolled 12 male volunteers who performed isometric plantar flexor contractions at 10–100% of maximum effort. During each plantar flexor contraction, the knee extensor muscles were isometrically contracted at 0%, 50%, or 100% of maximum effort. Electromyographic activity was recorded from the vastus lateralis, medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus muscles and quantified using the average rectified value (ARV). At lower plantar flexion torque, regression analysis identified a clear linear relationship between the MG and soleus ARVs and between the MG and LG ARVs, suggesting the presence of muscle synergy (r2 > 0.65). The contraction of the knee extensor muscles induced a significant change in the slope of this relationship for both pairs of muscles (MG × soleus, P = 0.002; MG × LG, P = 0.006). Similarly, the slope of the linear relationship between the plantar flexion torque and the ARV of the MG or soleus changed significantly with knee extensor contraction (P = 0.031 and P = 0.041, respectively). These results suggest that muscle synergies characterized by non-mechanical constraints are selectively recruited according to whether contraction of the knee extensor muscles is performed simultaneously, which is relatively consistent with the muscle synergy hypothesis. PMID:29107958

Muscle power is an independent determinant of pain and quality of life in knee osteoarthritis

USDA-ARS?s Scientific Manuscript database

OBJECTIVE: This study examined the relationships between leg muscle strength, power, and perceived disease severity in subjects with knee osteoarthritis (OA) in order to determine whether dynamic leg extensor muscle power would be associated with pain and quality of life in knee OA. METHODS: Baseli...

A Better ARED Squat

NASA Technical Reports Server (NTRS)

Caldwell, E. E.; Newby, N. J.; Ploutz-Snyder, L.

2014-01-01

The 0-G ARED squat under loads the legs relative to the 1g ARED squat. In 1g the knee extensor/flexor muscles are primarily engaged due to the body's center of gravity is behind the knees during the motion of the squat. As body weight does not play a sufficient role 0 G, a crewmember's load exposure is limited by the load delivered by ARED through the exercise bar. Prescription loads for lowerbody resistance exercise in microgravity aim to include 1-G exercise bar load in addition to the crewmember's Earth body weight (BW); however, pressure points from the bar and the 1BW increased load at the shoulders translating to higher loads on the back have been a historical limitation for shoulders, requiring a decrease in exercise load at the start of the mission. Analogous to crewmembers, bed rest subjects report limitations of exercising with high loads on the back while performing squats on the horizontal exercise fixture (HEF), a custom exercise device that serves as an analog to 0-G ARED. Improvements for increasing loads on the HEF squat were suggested by distributing total exercise load between the hips and the bar1. The same is recommended for the 0-G ARED squat, with using current equipment on the ISS, which include the T2 running harness and T2 bungees. Quantification of this improvement has been accessed through computational modeling. The purpose of this study is to characterize joint torque during a squat with a distribution in exercise load on the ARED in 0 G. The analysis used existing models from NASA's Digital Astronaut Project. The biomechanics squat model was integrated with the ARED model and T2 bungees. The spring constant for the bungees were derived from ground testing. Forward dynamic simulation was performed for various conditions including anchor point attachments on the footplate of the ARED, bar load, hip load, and gravitational environment. The model confirms joint torques at knees is lower relative to 1G conditions primarily because the load delivery system is just with the exercise bar in 0 G. By distributing partial loads through use of the bungees to the hips joint-torque profiles were altered during a squat and provided options to enhance targeting lower-body loading in aims as for an improved countermeasure.

Fatigue and recovery from dynamic contractions in men and women differ for arm and leg muscles.

PubMed

Senefeld, Jonathon; Yoon, Tejin; Bement, Marie Hoeger; Hunter, Sandra K

2013-09-01

Whether there is a gender difference in fatigue and recovery from maximal velocity fatiguing contractions and across muscles is not understood. Sixteen men and 19 women performed 90 isotonic contractions at maximal voluntary shortening velocity (maximal velocity concentric contractions, MVCC) with the elbow flexor and knee extensor muscles (separate days) at a load equivalent to 20% maximal voluntary isometric contraction (MVIC). Power (from MVCCs) decreased similarly for men and women for both muscles (P > 0.05). Men and women had similar declines in MVIC of elbow flexors, but men had greater reductions in knee extensor MVIC force and MVIC electromyogram activity than women (P < 0.05). The decline in MVIC and power was greater, and force recovery was slower for the elbow flexors compared with knee extensors. The gender difference in muscle fatigue often observed during isometric tasks was diminished during fast dynamic contractions for upper and lower limb muscles. Copyright © Published 2013 by Wiley Periodicals, Inc. This article is a US Government wmusork and, as such, is in the public domain in the United States of America.

Assessment of Eccentric Exercise-Induced Oxidative Stress Using Oxidation-Reduction Potential Markers

PubMed Central

Stagos, Dimitrios; Goutzourelas, Nikolaos; Ntontou, Amalia-Maria; Kafantaris, Ioannis; Deli, Chariklia K.; Poulios, Athanasios; Jamurtas, Athanasios Z.; Bar-Or, David; Kouretas, Dimitrios

2015-01-01

The aim of the present study was to investigate the use of static (sORP) and capacity ORP (cORP) oxidation-reduction potential markers as measured by the RedoxSYS Diagnostic System in plasma, for assessing eccentric exercise-induced oxidative stress. Nineteen volunteers performed eccentric exercise with the knee extensors. Blood was collected before, immediately after exercise, and 24, 48, and 72 h after exercise. Moreover, common redox biomarkers were measured, which were protein carbonyls, thiobarbituric acid-reactive substances, total antioxidant capacity in plasma, and catalase activity and glutathione levels in erythrocytes. When the participants were examined as one group, there were not significant differences in any marker after exercise. However, in 11 participants there was a high increase in cORP after exercise, while in 8 participants there was a high decrease. Thus, the participants were divided in low cORP group exhibiting significant decrease in cORP after exercise and in high cORP group exhibiting significant increase. Moreover, only in the low cORP group there was a significant increase in lipid peroxidation after exercise suggesting induction of oxidative stress. The results suggested that high decreases in cORP values after exercise may indicate induction of oxidative stress by eccentric exercise, while high increases in cORP values after exercise may indicate no existence of oxidative stress. PMID:25874019

Low back and lower-limb muscle performance in male and female recreational runners with chronic low back pain.

PubMed

Cai, Congcong; Kong, Pui W

2015-06-01

Controlled laboratory study, cross-sectional. To compare lumbar extensor muscle fatigability, lumbar stabilizing muscle activation, and lower-limb strength between male and female runners with chronic low back pain (LBP) and healthy runners. Little is known about muscle performance in runners with chronic LBP. Eighteen recreational runners with chronic LBP (9 men, 9 women; mean age, 27.8 years) and 18 healthy recreational runners (9 men, 9 women; mean age, 24.6 years) were recruited. The median frequency slopes for bilateral iliocostalis and longissimus were calculated from electromyographic signals captured during a 2-minute Sorensen test. The thickness changes of the transversus abdominis and lumbar multifidus between resting and contraction were measured using an ultrasound scanner. Peak concentric torques of the bilateral hip extensors, hip abductors, and knee extensors were measured using an isokinetic dynamometer at 60°/s. The average values for both sides were used for statistical analysis. When averaged across sexes, peak knee extensor torque was 12.2% lower in the LBP group compared to the healthy group (mean difference, 0.29 Nm/kg; 95% confidence interval: 0.06, 0.53; P = .016). Male runners with chronic LBP exhibited smaller lumbar multifidus thickness changes compared to healthy male runners (mean difference, 0.13 cm; 95% confidence interval: 0.01, 0.25; P = .033). No other group differences were observed. Runners with chronic LBP exhibited diminished knee extensor strength compared to healthy runners. Male runners with chronic LBP demonstrated additional deficits in lumbar multifidus activation.

Eliminating impingement optimizes patellar biomechanics in high knee flexion.

PubMed

Tang, Qi-heng; Zhou, Yi-xin; Tang, Jing; Shao, Hong-yi; Wang, Guang-zhi

2010-08-01

We investigated the impact of eliminating the impingement between extensor mechanism and tibial insert on patellar tracking and patellar ligament tension in high knee flexion. Six cadaveric specimens were tested on an Oxford-type testing rig. The Genesis II knee system was implanted into each specimen knee with the traditional tibial insert and high-flex insert successively. Compared to traditional insert, the high-flex insert was characterized with a chambered anterior post and a chambered anterior lip which eliminates patella-post and patellar ligament-anterior lip impingements. The patella was tracked with an NDI Optotrak Certus system. The patellar ligament tension was measured using a NKB S-type tension transducer. There was a decrease of resultant patellar translation relative to the femur with statistically significant (P<0.05) at 90 degrees to 150 degrees of knee flexion and a decrease of patellar ligament tension with statistical significance (P<0.05) at 100 degrees, 120 degrees, 130 degrees, and 140 degrees of flexion using high-flex insert compared to traditional insert. Eliminating the impingement between extensor mechanism and implant in high knee flexion altered patellar tracking and reduced patellar ligament tension, which would facilitate high knee flexion.

Changes in transverse relaxation time of quadriceps femoris muscles after active recovery exercises with different intensities.

PubMed

Mukaimoto, Takahiro; Semba, Syun; Inoue, Yosuke; Ohno, Makoto

2014-01-01

The purpose of this study was to examine the changes in the metabolic state of quadriceps femoris muscles using transverse relaxation time (T2), measured by muscle functional magnetic resonance (MR) imaging, after inactive or active recovery exercises with different intensities following high-intensity knee-extension exercise. Eight healthy men performed recovery sessions with four different conditions for 20 min after high-intensity knee-extension exercise on separate days. During the recovery session, the participants conducted a light cycle exercise for 20 min using a cycle (50%, 70% and 100% of the lactate threshold (LT), respectively: active recovery), and inactive recovery. The MR images of quadriceps femoris muscles were taken before the trial and after the recovery session every 30 min for 120 min. The percentage changes in T2 for the rectus femoris and vastus medialis muscles after the recovery session in 50% LT and 70% LT were significantly lower than those in either inactive recovery or 100% LT. There were no significant differences in those for vastus lateralis and vastus intermedius muscles among the four trials. The percentage changes in T2 of rectus femoris and vastus medialis muscles after the recovery session in 50% LT and 70% LT decreased to the values before the trial faster than those in either inactive recovery or 100% LT. Those of vastus lateralis and vastus intermedius muscles after the recovery session in 50% LT and 70% LT decreased to the values before the trial faster than those in 100% LT. Although the changes in T2 after active recovery exercises were not uniform in exercised muscles, the results of this study suggest that active recovery exercise with the intensities below LT are more effective to recover the metabolic state of quadriceps femoris muscles after intense exercise than with either intensity at LT or inactive recovery.

Do oarsmen have asymmetries in the strength of their back and leg muscles?

PubMed

Parkin, S; Nowicky, A V; Rutherford, O M; McGregor, A H

2001-07-01

The aim of this study was to establish whether asymmetry of the strength of the leg and trunk musculature is more prominent in rowers than in controls. Nineteen oarsmen and 20 male controls matched for age, height and body mass performed a series of isokinetic and isometric strength tests on an isokinetic dynamometer. These strength tests focused on the trunk and leg muscles. Comparisons of strength were made between and within groups for right and left symmetry patterns, hamstring: quadriceps ratios, and trunk flexor and extensor ratios. The results revealed no left and right asymmetries in either the knee extensor or flexor strength parameters (including both isometric and isokinetic measures). Knee extensor strength was significantly greater in the rowing population, but knee flexor strength was similar between the two groups. No difference was seen between the groups for the hamstring: quadriceps strength ratio. In the rowing population, stroke side had no influence on leg strength. No differences were observed in the isometric strength of the trunk flexors and extensors between groups, although EMG activity was significantly higher in the rowing population. Patterns of asymmetry of muscle activity were observed between the left and right erector spinae muscles during extension, which was significantly related to rowing side (P < 0.01). These observations could be related to the high incidence of low back pain in oarsmen.

[Effect factors analysis of knee function recovery after distal femoral fracture operation].

PubMed

Bei, Chaoyong; Wang, Ruiying; Tang, Jicun; Li, Qiang

2009-09-01

To investigate the effect factors of knee function recovery after operation in distal femoral fractures. From January 2001 to May 2007, 92 cases of distal femoral fracture were treated. There were 50 males and 42 females, aged 20-77 years old (average 46.7 years old). Fracture was caused by traffic accident in 48 cases, by falling from height in 26 cases, by bruise in 12 cases and by tumble in 6 cases. According to Müller's Fracture classification, there were 29 cases of type A, 12 cases of type B and 51 cases of type C. According to American Society of Anesthesiologists (ASA) classification, there were 21 cases of grade I, 39 cases of grade II, 24 cases of grade III, and 8 cases of grade IV. The time from injury to operation was 4 hours to 24 days with an average of 7 days. Anatomical plate was used in 43 cases, retrograde interlocking intramedullary nail in 37 cases, and bone screws, bolts and internal fixation with Kirschner pins in 12 cases. After operation, the HSS knee function score was used to evaluate efficacy. Ten related factors were applied for statistical analysis, to knee function recovery after operation in distal femoral fractures, such as age, sex, preoperative ASA classification, injury to surgery time, fracture type, treatment, reduction quality, functional exercise after operation, whether or not CPM functional training and postoperative complications. Wound healed by first intention in 88 cases, infection occurred in 4 cases. All patients followed up 16-32 months with an average of 23.1 months. Clinical union of fracture was achieved within 3-7 months after operation. Extensor device adhesions and the scope of activities of <80 degrees occurred in 29 cases, traumatic arthritis in 25 cases, postoperative fracture displacement in 6 cases, mild knee varus or valgus in 7 cases and implant loosening in 6 cases. According to HSS knee function score, the results were excellent in 52 cases, good in 15 cases, fair in 10 cases and poor in 15 cases with an excellent and good rate of 72.83%. Single factor analysis showed that age, preoperative ASA classification, fracture type, reduction quality, whether or not CPM functional exercise, and postoperative complications were significantly in knee function recovery (P < 0.05). logistic regression analysis showed that the fracture type, quality of reduction, whether or not CPM functional exercise, and age were major factors in the knee joint function recovery. Age, preoperative ASA classification, fracture type, reduction quality, and whether or not CPM functional training, postoperative complications factors may affect the knee joint function recovery. Adjustment to the patient's preoperative physical status, fractures anatomic reduction and firm fixation, early postoperative active and passive functional exercises, less postoperative complications can maximize the restoration of knee joint function.

A Yoga Strengthening Program Designed to Minimize the Knee Adduction Moment for Women with Knee Osteoarthritis: A Proof-Of-Principle Cohort Study

PubMed Central

2015-01-01

People with knee osteoarthritis may benefit from exercise prescriptions that minimize knee loads in the frontal plane. The primary objective of this study was to determine whether a novel 12-week strengthening program designed to minimize exposure to the knee adduction moment (KAM) could improve symptoms and knee strength in women with symptomatic knee osteoarthritis. A secondary objective was to determine whether the program could improve mobility and fitness, and decrease peak KAM during gait. The tertiary objective was to evaluate the biomechanical characteristics of this yoga program. In particular, we compared the peak KAM during gait with that during yoga postures at baseline. We also compared lower limb normalized mean electromyography (EMG) amplitudes during yoga postures between baseline and follow-up. Primary measures included self-reported pain and physical function (Knee injury and Osteoarthritis Outcome Score) and knee strength (extensor and flexor torques). Secondary measures included mobility (six-minute walk, 30-second chair stand, stair climbing), fitness (submaximal cycle ergometer test), and clinical gait analysis using motion capture synchronized with electromyography and force measurement. Also, KAM and normalized mean EMG amplitudes were collected during yoga postures. Forty-five women over age 50 with symptomatic knee osteoarthritis, consistent with the American College of Rheumatology criteria, enrolled in our 12-week (3 sessions per week) program. Data from 38 were analyzed (six drop-outs; one lost to co-intervention). Participants experienced reduced pain (mean improvement 10.1–20.1 normalized to 100; p<0.001), increased knee extensor strength (mean improvement 0.01 Nm/kg; p = 0.004), and increased flexor strength (mean improvement 0.01 Nm/kg; p = 0.001) at follow-up compared to baseline. Participants improved mobility on the six-minute walk (mean improvement 37.7 m; p<0.001) and 30-second chair stand (mean improvement 1.3; p = 0.006) at follow-up compared to baseline. Fitness and peak KAM during gait were unchanged between baseline and follow-up. Average KAM during the yoga postures were lower than that of normal gait. Normalized mean EMG amplitudes during yoga postures were up to 31.0% of maximum but did not change between baseline and follow-up. In this cohort study, the yoga-based strengthening postures that elicit low KAMs improved knee symptoms and strength in women with knee OA following a 12 week program (3 sessions per week). The program also improved mobility, but did not improve fitness or reduce peak KAM during gait. The KAM during the yoga postures were lower than that of normal gait. Overall, the proposed program may be useful in improving pain, strength, and mobility in women with knee osteoarthritis. Clinical efficacy needs to be assessed using a randomized controlled trial design. Trial Registration ClinicalTrials.gov NCT02146105 PMID:26367862

Neuromuscular blockade of slow twitch muscle fibres elevates muscle oxygen uptake and energy turnover during submaximal exercise in humans.

PubMed

Krustrup, Peter; Secher, Niels H; Relu, Mihai U; Hellsten, Ylva; Söderlund, Karin; Bangsbo, Jens

2008-12-15

We tested the hypothesis that a greater activation of fast-twitch (FT) fibres during dynamic exercise leads to a higher muscle oxygen uptake (VO2 ) and energy turnover as well as a slower muscle on-kinetics. Subjects performed one-legged knee-extensor exercise for 10 min at an intensity of 30 W without (CON) and with (CUR) arterial injections of the non-depolarizing neuromuscular blocking agent cisatracurium. In CUR, creatine phosphate (CP) was unaltered in slow twitch (ST) fibres and decreased (P < 0.05) by 28% in FT fibres, whereas in CON, CP decreased (P < 0.05) by 33% and 23% in ST and FT fibres, respectively. From 127 s of exercise, muscle VO2 was higher (P < 0.05) in CUR compared to CON (425 +/- 25 (+/- S.E.M.) versus 332 +/- 30 ml min(-1)) and remained higher (P < 0.05) throughout exercise. Using monoexponential fitting, the time constant of the exercise-induced muscle VO2 response was slower (P < 0.05) in CUR than in CON (55 +/- 6 versus 33 +/- 5 s). During CUR and CON, muscle homogenate CP was lowered (P < 0.05) by 32 and 35%, respectively, and also muscle lactate production was similar in CUR and CON (37.8 +/- 4.1 versus 35.2 +/- 6.2 mmol). Estimated total muscle ATP turnover was 19% higher (P < 0.05) in CUR than in CON (1196 +/- 90 versus 1011 +/- 59 mmol) and true mechanical efficiency was lower (P < 0.05) in CUR than in CON (26.2 +/- 2.0 versus 30.9 +/- 1.5%). In conclusion, the present findings provide evidence that FT fibres are less efficient than ST fibres in vivo at a contraction frequency of 1 Hz, and that the muscle VO2 kinetics is slowed by FT fibre activation.

Women show similar central and peripheral fatigue to men after half-marathon.

PubMed

Boccia, Gennaro; Dardanello, Davide; Tarperi, Cantor; Festa, Luca; La Torre, Antonio; Pellegrini, Barbara; Schena, Federico; Rainoldi, Alberto

2018-06-01

Women are known to be less fatigable than men in single-joint exercises, but fatigue induced by running has not been well understood. Here we investigated sex differences in central and peripheral fatigue and in rate of force development (RFD) in the knee extensors after a half-marathon run. Ten male and eight female amateur runners (aged 25-50 years) were evaluated before and immediately after a half-marathon race. Knee extensors forces were obtained under voluntary and electrically evoked isometric contractions. Maximal voluntary isometric contraction (MVC) force and peak RFD were recorded. Electrically doublet stimuli were delivered during the MVC and at rest to calculate the level of voluntary activation and the resting doublet twitch. After the race, decreases in MVC force (males: -11%, effect size [ES] 0.52; females: -11% ES 0.33), voluntary activation (males: -6%, ES 0.87; females: -4%, ES 0.72), and resting doublet twitch (males: -6%, ES 0.34; females: -8%, ES 0.30) were found to be similar between males and females. The decrease in peak RFD was found to be similar between males and females (males: -14%, ES 0.43; females: -15%, ES 0.14). Half-marathon run induced both central and peripheral fatigue, without any difference between men and women. The maximal and explosive strength loss was found similar between sexes. Together, these findings do not support the need of sex-specific training interventions to increase the tolerance to neuromuscular fatigue in half-marathoners.

Relationships of muscle strength and bone mineral density in ambulatory children with cerebral palsy.

PubMed

Chen, C-L; Lin, K-C; Wu, C-Y; Ke, J-Y; Wang, C-J; Chen, C-Y

2012-02-01

This work explores the relationships of muscle strength and areal bone mineral density (aBMD) in ambulatory children with cerebral palsy (CP). The knee extensor strength, but not motor function, was related to aBMD. Thus, muscle strength, especially antigravity muscle strength, was more associated with aBMD in these children than motor function. Muscle strength is related to bone density in normal children. However, no studies have examined these relationships in ambulatory children with CP. This work explores the relationships of muscle strength and aBMD in ambulatory children with CP. Forty-eight ambulatory children with spastic CP, aged 5-15 years, were classified into two groups based on Gross Motor Function Classification System levels: I (n = 28) and II (n = 20). Another 31 normal development (ND) children were recruited as the comparison group for the aBMD. Children with CP underwent assessments of growth, lumbar and distal femur aBMD, Gross Motor Function Measure-66 (GMFM-66), and muscle strength of knee extensor and flexor by isokinetic dynamometer. The distal femur aBMD, but not lumbar aBMD, was lower in children with CP than in ND children (p < 0.05). Children with level I had greater knee flexor strength and GMFM-66 scores than those with level II (p < 0.001). However, the knee extensor strength and distal femur and lumbar aBMD did not differ between two groups. Regression analysis revealed the weight and knee extensor strength, but not GMFM-66 scores, were related positively to the distal femur and lumbar aBMD (adjusted r (2) = 0.56-0.65, p < 0.001). These results suggest the muscle strength, especially antigravity muscle strength, were more associated with the bone density of ambulatory children with CP than motor function. The data may allow clinicians for early identifying the ambulatory CP children of potential low bone density.

Contribution of Knee Flexor and Extensor Strength on Sex-Specific Energy Absorption and Torsional Joint Stiffness During Drop Jumping

PubMed Central

Schmitz, Randy J.; Shultz, Sandra J.

2010-01-01

Abstract Context: Lower extremity injury often occurs during abrupt deceleration when attempting to change the body's direction. Although sex-specific biomechanics have been implicated in the greater risk of acute knee injury in women than in men, it is unknown if sex differences in thigh strength affect sex-specific energy absorption and torsional joint stiffness patterns. Objective: To determine sex differences in energy absorption patterns and joint stiffnesses of the lower extremity during a drop jump and to determine if these sex differences were predicted by knee extensor and flexor strength. Design: Cross-sectional study. Setting: Laboratory environment. Patients or Other Participants: Recreationally active, college-aged students (41 women: age  =  22.1 ± 2.9 years, height  =  1.63 ± 0.07 m, mass  =  59.3 ± 8.0 kg; 40 men: age  =  22.4 ± 2.8 years, height  =  1.77 ± 0.1 m, mass  =  80.9 ± 14.1 kg). Intervention(s): Participants performed knee flexor and extensor maximal voluntary isometric contractions followed by double-leg drop-jump landings. Main Outcome Measure(s): Lower extremity joint energetics (J × N−1 × m−1) and torsional joint stiffnesses (Nm × N−1 × m−1 × degrees−1) were calculated for the hip, knee, and ankle during the initial landing phase. Body weight was measured in newtons and height was measured in meters. Sex comparisons were made and sex-specific regressions determined if thigh muscle strength (Nm/kg) predicted sagittal-plane landing energetics and stiffnesses. Results: Women absorbed 69% more knee energy and had 36% less hip torsional stiffness than men. In women, greater knee extensor strength predicted greater knee energy absorption (R2  =  0.11, P  =  .04), and greater knee flexor strength predicted greater hip torsional stiffness (R2  =  0.12, P  =  .03). Conclusions: Sex-specific biomechanics during the deceleration phase of a drop jump revealed that women used a strategy to attempt to decrease system stiffness. Additionally, only female strength values were predictive of landing energetics and stiffnesses. These findings collectively demonstrated that the task may have been more difficult for women, resulting in a different movement strategy among those with different levels of thigh strength to safely complete the task. Future researchers should look at other predictive factors of observed sex differences. PMID:20831388

Neuromuscular Impairments Contributing to Persistently Poor and Declining Lower-Extremity Mobility Among Older Adults: New Findings Informing Geriatric Rehabilitation.

PubMed

Ward, Rachel E; Beauchamp, Marla K; Latham, Nancy K; Leveille, Suzanne G; Percac-Lima, Sanja; Kurlinski, Laura; Ni, Pengsheng; Goldstein, Richard; Jette, Alan M; Bean, Jonathan F

2016-08-01

To identify neuromuscular impairments most predictive of unfavorable mobility outcomes in late life. Longitudinal cohort study. Research clinic. Community-dwelling primary care patients aged ≥65 years (N=391) with self-reported mobility modifications, randomly selected from a research registry. Not applicable. Categories of decline in and persistently poor mobility across baseline, 1 and 2 years of follow-up in the Lower-Extremity Function scales of the Late-Life Function and Disability Instrument. The following categories of impairment were assessed as potential predictors of mobility change: strength (leg strength), speed of movement (leg velocity, reaction time, rapid leg coordination), range of motion (ROM) (knee flexion/knee extension/ankle ROM), asymmetry (asymmetry of leg strength and knee flexion/extension ROM measures), and trunk stability (trunk extensor endurance, kyphosis). The largest effect sizes were found for baseline weaker leg strength (odds ratio [95% confidence interval]: 3.45 [1.72-6.95]), trunk extensor endurance (2.98 [1.56-5.70]), and slower leg velocity (2.35 [1.21-4.58]) predicting a greater likelihood of persistently poor function over 2 years. Baseline weaker leg strength, trunk extensor endurance, and restricted knee flexion motion also predicted a greater likelihood of decline in function (1.72 [1.10-2.70], 1.83 [1.13-2.95], and 2.03 [1.24-3.35], respectively). Older adults exhibiting poor mobility may be prime candidates for rehabilitation focused on improving these impairments. These findings lay the groundwork for developing interventions aimed at optimizing rehabilitative care and disability prevention, and highlight the importance of both well-recognized (leg strength) and novel impairments (leg velocity, trunk extensor muscle endurance). Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Does insulin-like growth factor 1 genotype influence muscle power response to strength training in older men and women?

PubMed

Sood, Suchi; Hanson, Erik D; Delmonico, Matthew J; Kostek, Matthew C; Hand, Brian D; Roth, Stephen M; Hurley, Ben F

2012-02-01

The CA-repeat polymorphism in the insulin-like growth factor 1 (IGF1) gene promoter region has been associated with strength and circulating IGF-I protein levels. The purpose of the study was to determine if the IGF1 CA-repeat polymorphism influences muscle power at baseline and in response to ST in older adults. Knee extensor peak power (PP) was measured at 50, 60, and 70% of 1-RM strength before and after 10 weeks of unilateral knee extensor ST in older adults, aged 50-85 years, to determine the changes in absolute and relative PP with ST. Subjects (N = 114) were genotyped for the IGF1 CA-repeat polymorphism and grouped as homozygous for the 192 allele, heterozygous, or non-carriers of the 192 allele. The 192 homozygotes had significantly lower baseline PP at 50, 60, and 70% of 1-RM strength than the non-carriers when age, sex, and baseline fat-free mass were covaried (all P < 0.05). This same relationship was observed when the highest PP within these ranges was compared (e.g., 317.6 ± 13.5 for 192 homozygotes and 380.2 ± 16.3 for non-carriers of the 192 allele, P < 0.05). Both absolute and relative PP increased significantly with ST in all genotype groups as expected, but there were no significant relationships among IGF1 genotypes and any of the PP changes. Despite a significant relationship between IGF1 genotype and knee extensor peak power at baseline, IGF1 genotype does not appear to influence changes in knee extensor peak power with ST.

Relation between the Disability of the Arm, Shoulder and Hand Score and Muscle Strength in Post-Cardiac Surgery Patients

PubMed Central

Kasahara, Yusuke; Hiraki, Koji; Hirano, Yasuyuki; Watanabe, Satoshi

2017-01-01

Background: The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire is a valid and reliable patient-reported outcome measure. DASH can be assessed by self-reported upper extremity disability and symptoms. We aimed to examine the relationship between the physiological outcome of muscle strength and the DASH score after cardiac surgery. Methods: This cross-sectional study assessed 50 consecutive cardiac patients that were undergoing cardiac surgery. Physiological outcomes of handgrip strength and knee extensor muscle strength and the DASH score were measured at one month after cardiac surgery and were assessed. Results were analyzed using Spearman correlation coefficients. Results: The final analysis comprised 43 patients (men: 32, women: 11; age: 62.1 ± 9.1 years; body mass index: 22.1 ± 4.7 kg/m2; left ventricular ejection fraction: 53.5 ± 13.7%). Respective handgrip strength, knee extensor muscle strength, and DASH score were 27.4 ± 8.3 kgf, 1.6 ± 0.4 Nm/kg, and 13.3 ± 12.3, respectively. The DASH score correlated negatively with handgrip strength (r = −0.38, p = 0.01) and with knee extensor muscle strength (r = −0.32, p = 0.04). Conclusion: Physiological outcomes of both handgrip strength and knee extensor muscle strength correlated negatively with the DASH score. The DASH score appears to be a valuable tool with which to assess cardiac patients with poor physiological outcomes, particularly handgrip strength as a measure of upper extremity function, which is probably easier to follow over time than lower extremity function after patients complete cardiac rehabilitation. PMID:29186880

Conservative Treatment of Subacute Proximal Hamstring Tendinopathy Using Eccentric Exercises Performed With a Treadmill: A Case Report.

PubMed

Cushman, Daniel; Rho, Monica E

2015-07-01

Case report. Proximal hamstring tendinopathy in runners is characterized by pain with passive hip flexion with the knee extended, active hip extension, and pain with sitting. Relatively little literature exists on the condition, and publications on nonsurgical treatment protocols are even more scarce. Surgical intervention, which comprises the majority of literature for treatment of this condition, is an option for cases that fail to respond to nonsurgical treatment. The patient was a 34-year-old, otherwise healthy male triathlete with unilateral proximal hamstring tendinopathy diagnosed by ultrasound, who had pain only with running and prolonged sitting. After he failed to respond to 4 weeks of eccentric knee flexion and lumbopelvic musculature strengthening exercises, an eccentric hip extensor strengthening program using a treadmill was initiated. This treadmill exercise was performed on a daily basis, in addition to a lumbopelvic musculature strengthening program. The patient noted a decrease in pain within 2 weeks of initiating the new exercise, and was able to return to gradual running after 4 weeks and to speed training after 12 weeks. He returned to competition shortly thereafter and had no recurrence for 12 months after the initiation of therapy. His score on the Victorian Institute of Sport Assessment-proximal hamstring tendons improved from 23 on initial presentation to 83 at 12 weeks after the initiation of therapy. We described the management of a triathlete with subacute proximal hamstring tendinopathy, who responded well to nonsurgical treatment using eccentric hip extension strengthening using a treadmill. Therapy, level 4.

Conservative Treatment of Subacute Proximal Hamstring Tendinopathy Using Eccentric Exercises Performed With a Treadmill: A Case Report

PubMed Central

CUSHMAN, DANIEL; RHO, MONICA E.

2015-01-01

STUDY DESIGN Case report. BACKGROUND Proximal hamstring tendinopathy in runners is characterized by pain with passive hip flexion with the knee extended, active hip extension, and pain with sitting. Relatively little literature exists on the condition, and publications on nonsurgical treatment protocols are even more scarce. Surgical intervention, which comprises the majority of literature for treatment of this condition, is an option for cases that fail to respond to nonsurgical treatment. CASE DESCRIPTION The patient was a 34-year-old, otherwise healthy male triathlete with unilateral proximal hamstring tendinopathy diagnosed by ultrasound, who had pain only with running and prolonged sitting. After he failed to respond to 4 weeks of eccentric knee flexion and lumbopelvic musculature strengthening exercises, an eccentric hip extensor strengthening program using a treadmill was initiated. This treadmill exercise was performed on a daily basis, in addition to a lumbopelvic musculature strengthening program. OUTCOMES The patient noted a decrease in pain within 2 weeks of initiating the new exercise, and was able to return to gradual running after 4 weeks and to speed training after 12 weeks. He returned to competition shortly thereafter and had no recurrence for 12 months after the initiation of therapy. His score on the Victorian Institute of Sport Assessment-proximal hamstring tendons improved from 23 on initial presentation to 83 at 12 weeks after the initiation of therapy. DISCUSSION We described the management of a triathlete with subacute proximal hamstring tendinopathy, who responded well to nonsurgical treatment using eccentric hip extension strengthening using a treadmill. LEVEL OF EVIDENCE Therapy, level 4. PMID:25996362

Four Weeks of Nordic Hamstring Exercise Reduce Muscle Injury Risk Factors in Young Adults.

PubMed

Ribeiro-Alvares, João Breno; Marques, Vanessa B; Vaz, Marco A; Baroni, Bruno M

2018-05-01

Ribeiro-Alvares, JB, Marques, VB, Vaz, MA, and Baroni, BM. Four weeks of Nordic hamstring exercise reduce muscle injury risk factors in young adults. J Strength Cond Res 32(5): 1254-1262, 2018-The Nordic hamstring exercise (NHE) is a field-based exercise designed for knee-flexor eccentric strengthening, aimed at prevention of muscle strains. However, possible effects of NHE programs on other hamstring injury risk factors remain unclear. The purpose of this study was to investigate the effects of a NHE training program on multiple hamstring injury risk factors. Twenty physically active young adults were allocated into 2 equal-sized groups: control group (CG) and training group (TG). The TG was engaged in a 4-week NHE program, twice a week, 3 sets of 6-10 repetitions; while CG received no exercise intervention. The knee flexor and extensor strength were assessed through isokinetic dynamometry, the biceps femoris long head muscle architecture through ultrasound images, and the hamstring flexibility through sit-and-reach test. The results showed that CG subjects had no significant change in any outcome. TG presented higher percent changes than CG for hamstring isometric peak torque (9%; effect size [ES] = 0.27), eccentric peak torque (13%; ES = 0.60), eccentric work (18%; ES = 0.86), and functional hamstring-to-quadriceps torque ratio (13%; ES = 0.80). The NHE program led also to increased fascicle length (22%; ES = 2.77) and reduced pennation angle (-17%; ES = 1.27) in biceps femoris long head of the TG, without significant changes on muscle thickness. In conclusion, a short-term NHE training program (4 weeks; 8 training sessions) counteracts multiple hamstring injury risk factors in physically active young adults.

Exercise Responses to Gravity-Independent Flywheel Aerobic and Resistance Training.

PubMed

Owerkowicz, Tomasz; Cotter, Joshua A; Haddad, Fadia; Yu, Alvin M; Camilon, Marinelle L; Hoang, Theresa N; Jimenez, Daniel J; Kreitenberg, Arthur; Tesch, Per A; Caiozzo, Vincent J; Adams, Gregory R

2016-02-01

Although several exercise systems have been developed to mitigate the physiological deconditioning that occurs in microgravity, few have the capacity to positively impact multiple physiological systems and still meet the volume/mass requirements needed for missions beyond low Earth orbit. The purpose of this study was to test the gravity-independent Multi-Mode Exercise Device (M-MED) for both resistance (RE) and aerobic (AE) training stimuli. Eight men and nine women (mean age 22.0 ± 0.4 yr) completed 5 wk of training on the M-MED: RE 4 × 7 squats 2 d/wk, and AE 4 × 4-min rowing bouts at ∼90% Vo2max 3 d/wk. Pre- and post-training data collection included an aerobic capacity test, MR imaging, strength testing, and vastus lateralis muscle biopsy. Vo2max increased 8%, 3RM strength 18%, and quadriceps femoris cross-sectional area (CSA) 10%. Knee extensor strength increased at all isokinetic speeds tested. Subjects also demonstrated improved fatigue resistance in knee extension. At the cellular and molecular level, the biopsy revealed increases in mixed myofiber CSA (13%), citrate synthase activity (26%), total RNA concentration (24%), IGF-I mRNA (77%), and Type IIa myosin heavy chain (MHC) mRNA (8%), and a concomitant decrease in Type IIx MHC mRNA (-23%). None of the changes were gender-specific. Both the functional outcomes and biomarker changes indicate that a very low volume of M-MED exercise results in robust adaptation in the cardiovascular and musculoskeletal systems. The M-MED has the potential to provide a wide range of countermeasure exercises and should be considered for testing in ground-based spaceflight simulation.

Kinesiotape and quadriceps strengthening with elastic band in women with knee osteoarthritis and overweight or obesity. A randomized clinical trial.

PubMed

León-Ballesteros, Saúl; Espinosa-Morales, Rolando; Clark-Peralta, Patricia; Gómez-Pineda, Ascención Guadalupe; Guadarrama-Becerril, Jaime Horacio

2018-04-07

The beneficial effects of exercise in the treatment of Osteoarthritis (OA) of the knee have been verified in several studies. Kinesiotaping (KT) has been popularized due to its reducing local pressure and increasing circulation, resulting in decreased pain. Determine the clinical effectiveness of strengthening therapy with KT in women with knee OA for pain reduction. Thirty two women with knee OA, aged 50-70 years, with overweight or obesity grade I, who were randomized into two groups: one with exercise and KT, and the other, with exercise and placebo technique. Both groups performed stretching and quadriceps strengthening exercise with the elastic band 3 days weekly for 6 weeks. Measurement of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale was taken as primary outcome. Stiffness and functionality of the same index and the Visual Analog Scale (VAS) for pain intensity were measured. At the end of the study, there were no significant differences between the groups. Both groups had a difference of 2.7 points with respect to the baseline measurement, change percentage of 32.2% and 31.1% for placebo and experimental respectively (p=0.2). KT plus quadriceps strengthening exercise does not offer advantages for improvement of pain compared with quadriceps strengthening exercise alone in knee OA. Copyright © 2018 Sociedad Espaola de Reumatologa y Colegio Mexicano de Reumatologa. Publicado por Elsevier España, S.L.U. All rights reserved.

Pain and fear avoidance partially mediate change in muscle strength during resistance exercise in women with fibromyalgia.

PubMed

Larsson, Anette; Palstam, Annie; Löfgren, Monika; Ernberg, Malin; Bjersing, Jan; Bileviciute-Ljungar, Indre; Gerdle, Björn; Kosek, Eva; Mannerkorpi, Kaisa

2017-11-21

Resistance exercise results in health benefits in fibromyalgia. The aim of this study was to determine the factors that mediate change in muscle strength in women with fibromyalgia as a result of resistance exercise. Sixty-seven women with fibromyalgia (age range 25-64 years) were included. Tests of muscle strength and questionnaires related to pain, fear avoidance and physical activity were carried out. Multivariable stepwise regression was used to analyse explanatory factors for change and predictors for final values of knee-extension force, elbow-flexion force and hand-grip force. Change in knee-extension force was explained by fear avoidance beliefs about physical activity at baseline, together with change in pain intensity, knee-extension force at baseline, age and body mass index (BMI) (R2=0.40, p = 0.013). Change in elbow-flexion force was explained by pain intensity at baseline, together with baseline fear avoidance beliefs about physical activity, BMI and elbow-flexion force at baseline (R2 = 0.32, p = 0.043). Change in hand-grip force was explained by hand-grip force at baseline, change in pain intensity and baseline fear avoidance (R2 = 0.37, p = 0.009). Final muscle strength was predicted by the same variables as change, except pain. Pain and fear avoidance are important factors to consider in rehabilitation using resistance exercise for women with fibromyalgia.

Effect of intensive diet and exercise on self-efficacy in overweight and obese adults with knee osteoarthritis: The IDEA randomized clinical trial.

PubMed

Mihalko, Shannon L; Cox, Phillip; Beavers, Daniel P; Miller, Gary D; Nicklas, Barbara J; Lyles, Mary; Hunter, David J; Eckstein, Felix; Guermazi, Ali; Loeser, Richard F; DeVita, Paul; Messier, Stephen P

2018-04-04

Physical activity decreases the risk of osteoarthritis (OA)-related disability; however, pain and lack of confidence represent barriers for older adults with knee OA. The purpose of this study was to examine (a) the baseline associations among self-efficacy and physical activity, function, and pain; (b) longitudinal changes in self-efficacy; and (c) whether self-efficacy mediates treatment effects on clinical outcomes. The Intensive Diet and Exercise for Arthritis (IDEA) trial was a single-blind, randomized controlled 18-month study including 454 overweight/obese older adults (M age = 66 years) with knee OA. Participants were randomized to one of three interventions: exercise (E), diet-induced weight loss (D), or both (D+E). Self-efficacy for gait, balance, and walking duration were assessed at baseline, 6 months, and 18 months. Baseline associations were tested using Pearson correlations, and group least squares means were compared using mixed linear models at follow-up. Participants with higher self-efficacy reported significantly better physical function and less knee pain at baseline, walked farther (6-min walk), and were more physically active (all |r| > 0.12, all p < .01). Significant differences between groups were detected for all self-efficacy measures at 18 months; the D+E group reported significantly (all p < .005) higher self-efficacy for gait, walking duration, and balance compared with the D- or E-only groups. Self-efficacy significantly (p < .05) mediated treatment effects on physical function and pain at 18 months. A combined intervention of diet-induced weight loss and exercise is the treatment of choice to maximize self-efficacy, improve physical function, and reduce pain in overweight/obese adults with knee OA.

Effect of Seat Tube Angle and Exercise Intensity on Muscle Activity Patterns in Cyclists

PubMed Central

DUGGAN, WILL; DONNE, BERNARD; FLEMING, NEIL

2017-01-01

Previous studies have reported improved efficiency at steeper seat tube angle (STA) during ergometer cycling; however, neuromuscular mechanisms have yet to be fully determined. The current study investigated effects of STA on lower limb EMG activity at varying exercise intensities. Cyclists (n=11) were tested at 2 workloads; 160W and an individualised workload (IWL) equivalent to lactate threshold (TLac) minus 10%δ (derived from maximal incremental data), using 3 STA (70, 75 and 80°). Electromyographic data from Vastus Medialis (VM), Rectus Femoris (RF), Vastus Lateralis (VL) and Biceps Femoris (BF) were assessed. The timing and magnitude of activation were quantified and analysed using a two-way ANOVA. STA had significant (P < 0.05) effects on timing of onset and offset of VM, timing of offset of VL, and angle at peak for RF, all occurring later at 80 vs. 70° STA at IWL. In RF, increased activity occurred during the first 108° of the crank cycle at 80 vs. 70° at IWL (P < 0.01). As most of the power in the pedal stroke is generated during the mid-section of the down-stroke, movement of the activation range of knee extensors into the predominantly power phase of the pedal stroke would potentially account for increased efficiency and decreased cardio-respiratory costs. Greater activity of bi-articular RF, in the first 108º of the crank cycle at IWL (80 vs. 70º) may more closely resemble the pelvic stabilising activity of RF in running biomechanics; and potentially explain the more effective transition from cycling to running reported in triathletes using steeper STA. PMID:29399245

Ground reaction forces and knee mechanics in the weight acceptance phase of a dance leap take-off and landing.

PubMed

Kulig, Kornelia; Fietzer, Abbigail L; Popovich, John M

2011-01-01

Aesthetic constraints allow dancers fewer technique modifications than other athletes to negotiate the demands of leaping. We examined vertical ground reaction force and knee mechanics during a saut de chat performed by healthy dancers. It was hypothesized that vertical ground reaction force during landing would exceed that of take-off, resulting in greater knee extensor moments and greater knee angular stiffness. Twelve dancers (six males, six females; age 18.9 ± 1.2 years, mass 59.2 ± 9.5 kg, height 1.68 ± 0.08 m, dance training 8.9 ± 5.1 years) with no history of low back pain or lower extremity pathology participated in the study. Saut de chat data were captured using an eight-camera Vicon system and AMTI force platforms. Peak ground reaction force was 26% greater during the landing phase, but did not result in increased peak knee extensor moments. Taking into account the 67% greater knee angular displacement during landing, this resulted in less knee angular stiffness during landing. In conclusion, landing was accomplished with less knee angular stiffness despite the greater peak ground reaction force. A link between decreased joint angular stiffness and increased soft tissue injury risk has been proposed elsewhere; therefore, landing from a saut de chat may be more injurious to the knee soft tissue than take-off.

Sexual health in patients with rheumatoid arthritis and the association between physical fitness and sexual function: a cross-sectional study.

PubMed

Dorner, Thomas Ernst; Berner, Carolin; Haider, Sandra; Grabovac, Igor; Lamprecht, Thomas; Fenzl, Karl Heinrich; Erlacher, Ludwig

2018-06-01

The aim of this study was to examine sexual health in patients with rheumatoid arthritis (RA), and to analyse factors associated with sexual health with a focus on physical fitness. One hundred RA patients aged between 18 and 65 years were included in a cross-sectional study. Handgrip strength and knee extensor strength were measured with a dynamometer, and physical performance with the Short Physical Performance Battery (SPPB). Fifty-four patients, mean age 47.8 (SD 10.6) years, 61% female, answered a questionnaire about sexual health. Fifty-seven percent reported, at least, sometimes having difficulty with sexual intercourse (27.8% due to joint stiffness, 24.1% due to fatigue, 18.5% due to pain). Handgrip strength and knee extensor strength significantly correlated with the desire to engage in sexual intercourse, frequency of sexual contact and satisfaction with overall sex life. The SPPB total score correlated with satisfaction with overall sex life, and the SPPB repeated chair stands test with the desire to have sexual intercourse and satisfaction with overall sex life. After adjusting for age, gender, disease activity, comorbidity, co-medication and pain intensity, the repeated chair stands test remained significantly associated with the frequency of sexual contact (0.53; 0.01-1.05) and with satisfaction with overall sex life (1.39; 0.28-2.51). The results of this study show that problems with sexual health are highly prevalent in patients with RA. The ability to rise from a chair is associated with sexual function, independent of disease activity and pain intensity.

Effects of Series Elasticity on the Human Knee Extension Torque-Angle Relationship in Vivo

ERIC Educational Resources Information Center

Kubo, Keitaro; Ohgo, Kazuya; Takeishi, Ryuichi; Yoshinaga, Kazunari; Tsunoda, Naoya; Kanehisa, Hiroaki; Fukunaga, Tetsuo

2006-01-01

The purpose of this study was to investigate the effects of series elasticity on the torque-angle relationship of the knee extensors in vivo. Forty-two men volunteered to take part in the present study. The participants performed maximal voluntary isometric contractions at eight knee-joint angles (40, 50, 60, 70, 80, 90, 100, 110[degree]). The…

Acute effects of self-selected regimen of rapid body mass loss in combat sports athletes.

PubMed

Timpmann, Saima; Oöpik, Vahur; Pääsuke, Mati; Medijainen, Luule; Ereline, Jaan

2008-01-01

The purpose of the study was to assess the acute effects of the self-selected regimen of rapid body mass loss (RBML) on muscle performance and metabolic response to exercise in combat sports athletes. Seventeen male athletes (20.8 ± 1.0 years; mean ± SD) reduced their body mass by 5.1 ± 1.1% within 3 days. The RBML was achieved by a gradual reduction of energy and fluid intake and mild sauna procedures. A battery of tests was performed before (Test 1) and immediately after (Test 2) RBML. The test battery included the measurement of the peak torque of knee extensors for three different speeds, assessment of total work (Wtot) performed during a 3-min intermittent intensity knee extension exercise and measurements of blood metabolites (ammonia, lactate, glucose and urea). Absolute peak torque was lower in Test 2 compared with Test 1 at angular velocities of 1.57 rad·s(-1) (218.6 ± 40.9 vs. 234.4 ± 42.2 N·m; p = 0.013) and 3.14 rad·s(-1) (100.3 ± 27.8 vs. 111.7 ± 26.2 N·m; p = 0.008). The peak torque in relation to body mass remained unchanged for any speed. Absolute Wtot was lower in Test 2 compared with Test 1 (6359 ± 2326 vs. 7452 ± 3080 J; p = 0.003) as well as Wtot in relation to body mass (89.1 ± 29.9 vs. 98.6 ± 36.4 J·kg(-1); p = 0.034), respectively. As a result of RBML, plasma urea concentration increased from 4.9 to 5.9 mmol·l(-1) (p = 0.003). The concentration of ammonia in a post-test sample in Test 2 tended to be higher in comparison with Test 1 (80.9 ± 29.1 vs. 67.6 ± 26.5 mmol·l(-1); p = 0.082). The plasma lactate and glucose responses to exercise were similar in Test 1 and Test 2. We conclude that the self-selected regimen of RBML impairs muscle performance in 3-min intermittent intensity exercise and induces an increase in blood urea concentration in experienced male combat sports athletes. Key pointsPrevious studies have revealed a negative effect of rapid body mass loss on performance. However, there are some performance characteristics that may not change or even improve.The methods used for inducing rapid body mass loss have been prescribed by researchers and not chosen by the subjects in many previous studies. The duration of tests, which have revealed a negative impact of rapid body mass loss on performance have also been rather long (5-6 min) in previous studies.We assessed the acute effects of the self-selected regimen of rapid body mass loss on muscle performance and metabolic response to 3-min intermittent intensity exercise in experienced male combat sports athletes.The results suggest that the self-selected regimen of rapid body mass loss impairs muscle performance in 3-min intermittent intensity exercise and induces an increase in blood urea concentration. Hence, the recent changes in the rules of some events (wrestling), including shortening of the duration of a match, have not reduced the likelihood of the occurrence of a negative impact of rapid body mass loss on athletes' performance capacity.

Addition of telephone coaching to a physiotherapist-delivered physical activity program in people with knee osteoarthritis: A randomised controlled trial protocol

PubMed Central

2012-01-01

Background Knee osteoarthritis (OA) is one of the most common and costly chronic musculoskeletal conditions world-wide and is associated with substantial pain and disability. Many people with knee OA also experience co-morbidities that further add to the OA burden. Uptake of and adherence to physical activity recommendations is suboptimal in this patient population, leading to poorer OA outcomes and greater impact of associated co-morbidities. This pragmatic randomised controlled trial will investigate the clinical- and cost-effectiveness of adding telephone coaching to a physiotherapist-delivered physical activity intervention for people with knee OA. Methods/Design 168 people with clinically diagnosed knee OA will be recruited from the community in metropolitan and regional areas and randomly allocated to physiotherapy only, or physiotherapy plus nurse-delivered telephone coaching. Physiotherapy involves five treatment sessions over 6 months, incorporating a home exercise program of 4–6 exercises (targeting knee extensor and hip abductor strength) and advice to increase daily physical activity. Telephone coaching comprises 6–12 telephone calls over 6 months by health practitioners trained in applying the Health Change Australia (HCA) Model of Health Change to provide behaviour change support. The telephone coaching intervention aims to maximise adherence to the physiotherapy program, as well as facilitate increased levels of participation in general physical activity. The primary outcomes are pain measured by an 11-point numeric rating scale and self-reported physical function measured by the Western Ontario and McMaster Universities Osteoarthritis Index subscale after 6 months. Secondary outcomes include physical activity levels, quality-of-life, and potential moderators and mediators of outcomes including self-efficacy, pain coping and depression. Relative cost-effectiveness will be determined from health service usage and outcome data. Follow-up assessments will also occur at 12 and 18 months. Discussion The findings will help determine whether the addition of telephone coaching sessions can improve sustainability of outcomes from a physiotherapist-delivered physical activity intervention in people with knee OA. Trial Registration Australian New Zealand Clinical Trials Registry reference: ACTRN12612000308897 PMID:23231928

Osteoarthritis of the knee and hip and activity: a systematic international review and synthesis (OASIS).

PubMed

Vignon, Eric; Valat, Jean-Pierre; Rossignol, Michel; Avouac, Bernard; Rozenberg, Sylvie; Thoumie, Philippe; Avouac, Jérôme; Nordin, Margareta; Hilliquin, Pascal

2006-07-01

The goal of this study was to determine which activities in four domains, daily life, exercises, sports and occupational activities, should be recommended, in favor or against, for the patient suffering from knee or hip OA. Scientific literature was searched in Medline, Embase and Cochrane databases for articles in French or English, reporting original data. The articles were evaluated with standardized epidemiological criteria. Seventy-two articles were retained. Recommendations were graded according to the level of scientific evidence (A high, B moderate, C clinical consensus) and were formulated for primary care. For activity of daily life (ADL), the OASIS group states with a moderate level of scientific evidence, that ADL are a risk factor for knee OA and that risk increases with intensity and duration of activity. The group concludes that healthy subjects as well as OA patients in general can pursue a high level of physical activity, provided the activity is not painful and does not predispose to trauma (grade B). Radiographic or clinical OA is not a contraindication to promoting activity in patients who have a sedentary lifestyle (grade C). For exercises and other structured activities pursued with a goal of health improvement, the group states with a high level of scientific evidence that they have a favourable effect on pain and function in the sedentary knee OA patient. The OASIS group recommends the practice of exercises and other structured activities for the sedentary patient with knee OA (grade A). Static exercises are not favored over dynamic exercises, availability, preference and tolerance being the criteria for the choice of an exercise (grade A). As results deteriorate when exercises are stopped, they should be performed at a frequency of between one and three times per week (grade B). Professional assistance can be useful in improving initial compliance and perseverance (grade B). There is no scientific argument to support halting exercise in case of an OA flare-up (grade C). For sports and recreational activity, the group states with a high degree of scientific evidence, that these activities are a risk factor for knee and hip OA and that the risk correlates with intensity and duration of exposure. The group also states, with a high degree of scientific evidence, that the risk of OA associated with sport is lesser than that associated with a history of trauma and overweight. No firm conclusion could be drawn about the possible protective role of sports such as cycling, swimming or golf. The OASIS group recommends that athletes should be informed that joint trauma is a greater risk factor than the practice of sport (Grade A). The high level athlete should be informed that the risk of OA is associated with the duration and intensity of exposure (Grade B). The OA patient can continue to engage regularly in recreational sports as long as the activity does not cause pain (Grade C). The OA patient who practices a sport at risk for joint trauma should be encouraged to change sport (Grade C). For occupational activity, the OASIS group states with a high level of scientific evidence that there is a relationship between occupational activity and OA of the knee and hip. The precise nature of biomechanical stresses leading to OA remains unclear but factors such as high loads on the joint, unnatural body position, heavy lifting, climbing and jumping may contribute to knee and hip OA. The group recommends that taking an occupational history should always be part of managing the OA patient (Grade B). In the knee or hip OA patient, work-related activity that produces or maintains pain should be avoided (Grade B). Physicians should be alerted by the early knee and hip signs and symptoms in workers exposed to stresses that are known or supposed to favour knee or hip OA (Grade C).

Effect of Laser Therapy on Chronic Osteoarthritis of the Knee in Older Subjects

PubMed Central

Youssef, Enas Fawzey; Muaidi, Qassim Ibrahim; Shanb, Alsayed Abdelhameed

2016-01-01

Introduction: Osteoarthritis (OA) is a common degenerative joint disease particularly in older subjects. It is usually associated with pain, restricted range of motion, muscle weakness, difficulties in daily living activities and impaired quality of life. To determine the effects of adding two different intensities of low-level laser therapy (LLLT) to exercise training program on pain severity, joint stiffness, physical function, isometric muscle strength, range of motion of the knee, and quality of life in older subjects with knee OA. Methods: Patients were randomly assigned into three groups. They received 16 sessions, 2 sessions/week for 8 weeks. Group-I: 18 patients were treated with a laser dose of 6 J/cm2 with a total dose of 48 J. Group-II: 18 patients were treated with a laser dose of 3 J/cm2 with a total dose of 27 J. Group-III: 15 patients were treated with laser without emission as a placebo. All patients received same exercise training program including stretching and strengthening exercises. Patients were evaluated before and after intervention by visual analogue scale (VAS), the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index for quality of life, handheld dynamometer and universal goniometer. Results: T test revealed that there was a significant reduction in VAS and pain intensity, an increase in isometric muscle strength and range of motion of the knee as well as increase in physical functional ability in three treatment groups. Also analysis of variance (ANOVA) proved significant differences among them and the post hoc tests (LSD) test showed the best improvements for patients of the first group. Conclusion: It can be concluded that addition of LLLT to exercise training program is more effective than exercise training alone in the treatment of older patients with chronic knee OA and the rate of improvement may be dose dependent, as with 6 J/cm2 or 3 J/cm2. PMID:27330707

Greater glucose uptake heterogeneity in knee muscles of old compared to young men during isometric contractions detected by [18F]-FDG PET/CT

PubMed Central

Rudroff, Thorsten; Kindred, John H.; Benson, John-Michael; Tracy, Brian L.; Kalliokoski, Kari K.

2014-01-01

We used positron emission tomography/computed tomography (PET/CT) and [18F]-FDG to test the hypothesis that glucose uptake (GU) heterogeneity in skeletal muscles as a measure of heterogeneity in muscle activity is greater in old than young men when they perform isometric contractions. Six young (26 ± 6 years) and six old (77 ± 6 years) men performed two types of submaximal isometric contractions that required either force or position control. [18F]-FDG was injected during the task and PET/CT scans were performed immediately after the task. Within-muscle heterogeneity of knee muscles was determined by calculating the coefficient of variation (CV) of GU in PET image voxels within the muscles of interest. The average GU heterogeneity (mean ± SD) for knee extensors and flexors was greater for the old (35.3 ± 3.3%) than the young (28.6 ± 2.4%) (P = 0.006). Muscle volume of the knee extensors were greater for the young compared to the old men (1016 ± 163 vs. 598 ± 70 cm3, P = 0.004). In a multiple regression model, knee extensor muscle volume was a predictor (partial r = −0.87; P = 0.001) of GU heterogeneity for old men (R2 = 0.78; P < 0.001), and MVC force predicted GU heterogeneity for young men (partial r = −0.95, P < 0.001). The findings demonstrate that GU is more spatially variable for old than young men and especially so for old men who exhibit greater muscle atrophy. PMID:24904432

Evidence of compensatory joint kinetics during stair ascent and descent in Parkinson's disease.

PubMed

Conway, Zachary J; Silburn, Peter A; Blackmore, Tim; Cole, Michael H

2017-02-01

Stair ambulation is a challenging activity of daily life that requires larger joint moments than walking. Stabilisation of the body and prevention of lower limb collapse during this task depends upon adequately-sized hip, knee and ankle extensor moments. However, people with Parkinson's disease (PD) often present with strength deficits that may impair their capacity to control the lower limbs and ultimately increase their falls risk. To investigate hip, knee and ankle joint moments during stair ascent and descent and determine the contribution of these joints to the body's support in people with PD. Twelve PD patients and twelve age-matched controls performed stair ascent and descent trials. Data from an instrumented staircase and a three-dimensional motion analysis system were used to derive sagittal hip, knee and ankle moments. Support moment impulses were calculated by summing all extensor moment impulses and the relative contribution of each joint was calculated. Linear mixed model analyses indicated that PD patients walked slower and had a reduced cadence relative to controls. Although support moment impulses were typically not different between groups during stair ascent or descent, a reduced contribution by the ankle joint required an increased knee joint contribution for the PD patients. Despite having poorer knee extensor strength, people with PD rely more heavily on these muscles during stair walking. This adaptation could possibly be driven by the somewhat restricted mobility of this joint, which may provide these individuals with an increased sense of stability during these tasks. Copyright © 2016 Elsevier B.V. All rights reserved.

Individual Muscle use in Hamstring Exercises by Soccer Players Assessed using Functional MRI.

PubMed

Fernandez-Gonzalo, R; Tesch, P A; Linnehan, R M; Kreider, R B; Di Salvo, V; Suarez-Arrones, L; Alomar, X; Mendez-Villanueva, A; Rodas, G

2016-06-01

This study used functional magnetic resonance imaging (fMRI) to compare individual muscle use in exercises aimed at preventing hamstring injuries. Thirty-six professional soccer players were randomized into 4 groups, each performing either Nordic hamstring, flywheel leg curl, Russian belt or conic-pulley exercise. MRIs were performed before and immediately after a bout of 4 sets of 8 repetitions. Pre-post exercise differences in contrast shift (T2) were analyzed for the long (BFLh) and short head (BFSh) of biceps femoris, semitendinosus (ST), semimembranosus (SM) and gracilis (GR) muscles. Flywheel leg curl increased (P<0.001) T2 of GR (95%), ST (65%), BFSh (51%) and BFLh (14%). After the Nordic hamstring, GR (39%), ST (16%) and BFSh (14%) showed increased T2 (P<0.001). Russian belt and conic-pulley exercise produced subtle (P<0.02) T2 increases of ST (9 and 6%, respectively) and BFLh (7 and 6%, respectively). Russian belt increased T2 of SM (7%). Among exercises examined, flywheel leg curl showed the most substantial hamstring and GR muscle use. However, no single exercise executed was able to increase T2 of all hamstring and synergist muscles analyzed. It is therefore suggested that multiple exercises must be carried out to bring in, and fully activate all knee flexors and hip extensors. © Georg Thieme Verlag KG Stuttgart · New York.

Isokinetic strength and endurance during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bulbulian, R.; Bond, M.

1994-01-01

The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle ergometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

Isokinetic Strength and Endurance During 30-day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bond, M.; Bulbulian, R.

1994-01-01

The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle orgometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

Gait analysis of patients with an off-the-shelf total knee replacement versus customized bi-compartmental knee replacement.

PubMed

Wang, Henry; Foster, Jonathan; Franksen, Natasha; Estes, Jill; Rolston, Lindsey

2018-04-01

Newer TKR designs have been introduced to the market with the aim of overcoming common sizing problems with older TKR designs. Furthermore, since a sizable percentage of patients with OA present with disease limited to the medial/lateral knee compartment in addition to the patellofemoral joint, for whom, a customized bi-compartmental knee replacement (BKR) is available as a treatment option. To date, there is very little information regarding knee strength and mechanics during gait for patients implanted with these modern TKR and BKR designs. The purpose of the study was to evaluate knee strength and mechanics during walking for patients with either a modern off the shelf TKR or a customized BKR and compare these findings to a cohort of healthy controls. Twelve healthy controls, eight BKR, and nine TKR patients participated in the study. Maximal isometric knee strength was evaluated. 3D kinematic and kinetic analyses were conducted for level walking. The TKR knee exhibited less peak extensor torque when compared to, both the BKR and control limbs (p < 0.05). The TKR knee had less extensor moment at stance than both the BKR and control knees (p < 0.05). Both the BKR and control knees displayed larger internal rotation at stance than that of the TKR knee (p < 0.05). This study suggests that, for patients that exhibit isolated OA of the tibiofemoral joint, using a customized BKR implant is a viable treatment option and may contribute to superior mechanical advantages.

IS PAIN IN ONE KNEE ASSOCIATED WITH ISOMETRIC MUSCLE STRENGTH IN THE CONTRALATERAL LIMB? - DATA FROM THE OSTEOARTHRITIS INITIATIVE (OAI)

PubMed Central

Steidle, E.; Wirth, W.; Glass, N.; Ruhdorfer, A.; Cotofana, S.; Eckstein, F.; Segal, N. A.

2014-01-01

Objective Knee pain and muscle weakness confer risk for knee osteoarthritis incidence and progression. The purpose of this study was to determine whether unilateral knee pain influences contralateral thigh muscle strength. Design Of 4796 Osteoarthritis Initiative participants, 224 (mean±SD age 63.9±8.9 years) cases could be matched to a control. Cases were defined as having unilateral knee pain (numerical rating scale (NRS)≥4/10; ≥infrequent pain) and one pain-free knee (NRS 0–1; ≤infrequent pain; WOMAC≤1). Controls were defined as having bilaterally pain-free knees (NRS 0–1; ≤infrequent pain; WOMAC≤1). Maximal isometric muscle strength [N] was compared between limbs in participants with unilateral pain (cases), and between pain-free limbs of cases and controls. Results Knee extensor/flexor strength in pain-free limbs of cases was lower than in bilaterally pain-free controls (−5.5%/–8.4%; p=0.043/p=0.022). Within cases, maximum extensor/flexor strength was significantly lower in the painful than in the pain-free limb (−6.4%/4.1%; p<0.0001/p=0.015). Conclusions These results suggest that strength in limbs without knee pain is associated with the pain status of the contralateral knee. The strength difference between unilateral pain-free cases and matched bilateral pain-free controls was similar to that between limbs in persons with unilateral knee pain. Lower strength due to contralateral knee pain might be centrally mediated. PMID:25768069

Effects of Sun-style Tai Chi exercise on physical fitness and fall prevention in fall-prone older adults.

PubMed

Choi, Jung Hyun; Moon, Jung-Soon; Song, Rhayun

2005-07-01

This paper reports a study to determine changes in the physical fitness (knee and ankle muscle strength, balance, flexibility, and mobility), fall avoidance efficacy, and fall episodes of institutionalized older adults after participating in a 12-week Sun-style Tai Chi exercise programme. Fall prevention has a high priority in health promotion for older people because a fall is associated with serious morbidity in this population. Regular exercise is effective in fall prevention for older adults because of improvements in strength and balance. Tai Chi exercise is considered to offer great potential for health promotion and rehabilitation, particularly in the maintenance of good mental and physical condition in older people. A quasi-experimental design with a non-equivalent control group was used. Data were collected from September 2001 to January 2002. A total of 68 fall-prone older adults with a mean age of 77.8 years participated in the study, and 29 people in the Tai Chi group and 30 controls completed the post-test measures. The Tai Chi exercise programme was provided three times a week for 12 weeks in the experimental group. Data were analysed for group differences using t-tests. At post-test, the experimental group showed significantly improved muscle strength in knee and ankle flexors (P < 0.001) and extensors (P < 0.01), and improved flexibility (P < 0.01) and mobility (P < 0.001) compared with the control group. There was no significant group difference in fall episodes, but the relative risk ratio for the Tai Chi exercise group compared with the control group was 0.62. The experimental group reported significantly more confidence in fall avoidance than did the control group. The findings reveal that Tai Chi exercise programmes can safely improve physical strength and reduce fall risk for fall-prone older adults in residential care facilities.

Photobiomodulation therapy (PBMT) and/or cryotherapy in skeletal muscle restitution, what is better? A randomized, double-blinded, placebo-controlled clinical trial.

PubMed

de Paiva, Paulo Roberto Vicente; Tomazoni, Shaiane Silva; Johnson, Douglas Scott; Vanin, Adriane Aver; Albuquerque-Pontes, Gianna Móes; Machado, Caroline Dos Santos Monteiro; Casalechi, Heliodora Leão; de Carvalho, Paulo de Tarso Camillo; Leal-Junior, Ernesto Cesar Pinto

2016-12-01

Cryotherapy for post-exercise recovery remains widely used despite the lack of quality evidence. Photobiomodulation therapy (PBMT) studies (with both low-level laser therapy and light-emitting diode therapy) have demonstrated positive scientific evidence to suggest its use. The study aims to evaluate PBMT and cryotherapy as a single or combined treatment on skeletal muscle recovery after eccentric contractions of knee extensors. Fifty healthy male volunteers were recruited and randomized into five groups (PBMT, cryotherapy, cryotherapy + PBMT, PMBT + cryotherapy, or placebo) for a randomized, double-blinded, placebo-controlled trial that evaluated exercise performance (maximum voluntary contraction (MVC)), delayed onset muscle soreness (DOMS), and muscle damage (creatine kinase (CK)). Assessments were performed at baseline; immediately after; and at 1, 24, 48, 72, and 96 h. Comparator treatments was performed 3 min after exercise and repeated at 24, 48, and 72 h. PBMT was applied employing a cordless, portable GameDay ™ device (combination of 905 nm super-pulsed laser and 875- and 640-nm light-emitting diodes (LEDs); manufactured by Multi Radiance Medical ™ , Solon - OH, USA), and cryotherapy by flexible rubber ice packs. PBMT alone was optimal for post-exercise recovery with improved MVC, decreased DOMS, and CK activity (p < 0.05) from 24 to 96 h compared to placebo, cryotherapy, and cryotherapy + PBMT. In the PBMT + cryotherapy group, the effect of PBMT was decreased (p > 0.05) but demonstrated significant improvement in MVC, decreased DOMS, and CK activity (p < 0.05). Cryotherapy as single treatment and cryotherapy + PBMT were similar to placebo (p > 0.05). We conclude that PBMT used as single treatment is the best modality for enhancement of post-exercise restitution, leading to complete recovery to baseline levels from 24 h after high-intensity eccentric contractions.

Exercise-induced brachial artery vasodilation: effects of antioxidants and exercise training in elderly men

PubMed Central

Donato, Anthony J.; Uberoi, Abhimanyu; Bailey, Damian M.; Walter Wray, D.

2010-01-01

Aging, vascular function, and exercise are thought to have a common link in oxidative stress. Of the 28 subjects studied (young, 26 ± 2 yr; old, 71 ± 6 yr), 12 took part in a study to validate an antioxidant cocktail (AOC: vitamins C, E, and α-lipoic acid), while the remaining 8 young and 8 old subjects performed submaximal forearm handgrip exercise with placebo or AOC. Old subjects repeated forearm exercise with placebo or AOC following knee-extensor (KE) exercise training. Brachial arterial diameter and blood velocity (Doppler ultrasound) were measured at rest and during exercise. During handgrip exercise, brachial artery vasodilation in the old subjects was attenuated compared with that in young subjects following placebo (maximum = ∼3.0 and ∼6.0%, respectively). In contrast to the previously documented attenuation in exercise-induced brachial artery vasodilation in the young group with AOC, in the old subjects the AOC restored vasodilation (maximum = ∼7.0%) to match the young. KE training also improved exercise-induced brachial artery vasodilation. However, in the trained state, AOC administration no longer augmented brachial artery vasodilation in the elderly, but rather attenuated it. These data reveal an age-related pro-/antioxidant imbalance that impacts vascular function and show that exercise training is capable of restoring equilibrium such that vascular function is improved and the AOC-mediated reduction in free radicals now negatively impacts brachial artery vasodilation, as seen in the young. PMID:19966056

The Influence of Oral L-Glutamine Supplementation on Muscle Strength Recovery and Soreness Following Unilateral Knee Extension Eccentric Exercise.

PubMed

Legault, Zachary; Bagnall, Nicholas; Kimmerly, Derek S

2015-10-01

The study aimed to examine the effects that L-glutamine supplementation has on quadriceps muscle strength and soreness ratings following eccentric exercise. It was hypothesized that glutamine ingestion would quicken the recovery rate of peak force production and decrease muscle soreness ratings over a 72-hr recovery period. Sixteen healthy participants (8♀/8♂; 22 ± 4 years) volunteered in a double-blind, randomized, placebo-controlled crossover study. Supplement conditions consisted of isoenergetic placebo (maltodextrin, 0.6 g·kg-1·day-1) and L-glutamine (0.3 g·kg-1·day-1 + 0.3 g·kg-1·day-1 maltodextrin) ingestion once per day over 72 hr. Knee extensor peak torque at 0°, 30°, and 180° per second and muscle soreness were measured before, immediately following, 24, 48, and 72 hr posteccentric exercise. Eccentric exercise consisted of 8 sets (10 repetitions/set) of unilateral knee extension at 125% maximum concentric force with 2-min rest intervals. L-glutamine resulted in greater relative peak torque at 180°/sec both immediately after (71 ± 8% vs. 66 ± 9%), and 72 hr (91 ± 8% vs. 86 ± 7%) postexercise (all, p < .01). In men, L-glutamine produced greater (p < .01) peak torques at 30°/ sec postexercise. Men also produced greater normalized peak torques at 30°/sec (Nm/kg) in the L-glutamine condition than women (all, p < .05). In the entire sample, L-glutamine resulted in lower soreness ratings at 24 (2.8 ± 1.2 vs. 3.4 ± 1.2), 48 (2.6 ± 1.4 vs. 3.9 ± 1.2), and 72 (1.7 ± 1.2 vs. 2.9 ± 1.3) hr postexercise (p < .01). The L-glutamine supplementation resulted in faster recovery of peak torque and diminished muscle soreness following eccentric exercise. The effect of L-glutamine on muscle force recovery may be greater in men than women.

Muscle force distribution of the lower limbs during walking in diabetic individuals with and without polyneuropathy.

PubMed

Gomes, Aline A; Ackermann, Marko; Ferreira, Jean P; Orselli, Maria Isabel V; Sacco, Isabel C N

2017-11-09

Muscle force estimation could advance the comprehension of the neuromuscular strategies that diabetic patients adopt to preserve walking ability, which guarantees their independence as they deal with their neural and muscular impairments due to diabetes and neuropathy. In this study, the lower limb's muscle force distribution during gait was estimated and compared in diabetic patients with and without polyneuropathy. Thirty individuals were evaluated in a cross-sectional study, equally divided among controls (CG) and diabetic patients with (DNG) and without (DG) polyneuropathy. The acquired ground reaction forces and kinematic data were used as input variables for a scaled musculoskeletal model in the OpenSim software. The maximum isometric force of the ankle extensors and flexors was reduced in the model of DNG by 30% and 20%, respectively. The muscle force was calculated using static optimization, and peak forces were compared among groups (flexors and extensors of hip, knee, and ankle; ankle evertors; and hip abductors) using MANOVAs, followed by univariate ANOVAs and Newman-Keuls post-hoc tests (p < 0.05). From the middle to late stance phase, DG showed a lower soleus muscle peak force compared to the CG (p=0.024) and the DNG showed lower forces in the gastrocnemius medialis compared to the DG (p=0.037). At the terminal swing phase, the semitendinosus and semimembranosus peak forces showed lower values in the DG compared to the CG and DNG. At the late stance, the DNG showed a higher peak force in the biceps short head, semimembranosus, and semitendinosus compared to the CG and DG. Peak forces of ankle (flexors, extensors, and evertors), knee (flexors and extensors), and hip abductors distinguished DNG from DG, and both of those from CG. Both diabetic groups showed alterations in the force production of the ankle extensors with reductions in the forces of soleus (DG) and gastrocnemius medialis (DNG) seen in both diabetic groups, but only DNG showed an increase in the hamstrings (knee flexor) at push-off. A therapeutic approach focused on preserving the functionality of the knee muscles is a promising strategy, even if the ankle dorsiflexors and plantarflexors are included in the resistance training.

Immediate effects of whole body vibration on patellar tendon properties and knee extension torque.

PubMed

Rieder, F; Wiesinger, H-P; Kösters, A; Müller, E; Seynnes, O R

2016-03-01

Reports about the immediate effects of whole body vibration (WBV) exposure upon torque production capacity are inconsistent. However, the changes in the torque-angle relationship observed by some authors after WBV may hinder the measurement of torque changes at a given angle. Acute changes in tendon mechanical properties do occur after certain types of exercise but this hypothesis has never been tested after a bout of WBV. The purpose of the present study was to investigate whether tendon compliance is altered immediately after WBV, effectively shifting the optimal angle of peak torque towards longer muscle length. Twenty-eight subjects were randomly assigned to either a WBV (n = 14) or a squatting control group (n = 14). Patellar tendon CSA, stiffness and Young's modulus and knee extension torque-angle relationship were measured using ultrasonography and dynamometry 1 day before and directly after the intervention. Tendon CSA was additionally measured 24 h after the intervention to check for possible delayed onset of swelling. The vibration intervention had no effects on patellar tendon CSA, stiffness and Young's modulus or the torque-angle relationship. Peak torque was produced at ~70° knee angle in both groups at pre- and post-test. Additionally, the knee extension torque globally remained unaffected with the exception of a small (-6%) reduction in isometric torque at a joint angle of 60°. The present results indicate that a single bout of vibration exposure does not substantially alter patellar tendon properties or the torque-angle relationship of knee extensors.

Body Composition, Neuromuscular Performance, and Mobility: Comparison Between Regularly Exercising and Inactive Older Women.

PubMed

Rava, Anni; Pihlak, Anu; Ereline, Jaan; Gapeyeva, Helena; Kums, Tatjana; Purge, Priit; Jürimäe, Jaak; Pääsuke, Mati

2017-01-01

The purpose of this study was to evaluate the differences in body composition, neuromuscular performance, and mobility in healthy, regularly exercising and inactive older women, and examine the relationship between skeletal muscle indices and mobility. Overall, 32 healthy older women participated. They were divided into groups according to their physical activity history as regularly exercising (n = 22) and inactive (n = 10) women. Body composition, hand grip strength, leg extensor muscle strength, rapid force development, power output, and mobility indices were assessed. Regularly exercising women had lower fat mass and higher values for leg extensor muscle strength and muscle quality, and also for mobility. Leg extensor muscle strength and power output during vertical jumping and appendicular lean mass per unit of body mass were associated with mobility in healthy older women. It was concluded that long-term regular exercising may have beneficial effects on body composition and physical function in older women.

The Artificial Gravity Bed Rest Pilot Project: Effects on Knee Extensor and Plantar Flexor Muscle Groups

NASA Technical Reports Server (NTRS)

Caiozzo, V. J.; Haddad, F.; Lee, S.; Baker, M.; Baldwin, K. M.

2007-01-01

The goal of this project was to examine the effects of artificial gravity (2.5 g) on skeletal muscle strength and key anabolic/catabolic markers known to regulate muscle mass. Two groups of subjects were selected for study: 1) a 21 day-bed rest (BR) control (C) group (N=7); and 2) an AG group (N=8), which was exposed to 21 days of bed-rest plus daily 1 hr exposures to AG (2.5 g). This particular experiment was part of an integrated AG Pilot Project sponsored by NASA/Johnson Space Center. The in vivo torque-velocity relationships of the knee extensors and plantar flexors of the ankle were determined pre and post treatment. Also, pre- and post treatment biopsy samples were obtained from both the vastus lateralis and soleus muscles and were used, in part, for a series of analyses on gene expression (mRNA abundance) of key factors implicated in the anabolic versus catabolic state of the muscle. Post/Pre toque-velocity determinations revealed greater decrements in knee extensor performance in the C versus AG group (P less than 0.04). The plantar flexor muscle group of the AG subjects actually demonstrated a net gain in torque-velocity relationship; whereas, in the C group the overall post/pre responses declined (AG vs C; P less than 0.001). Measurements of muscle fiber cross-sectional area (for both muscles) demonstrated a loss of approx. 20% in the C group while no losses were evident in the AG group. RT-PCR analyses of muscle biopsy specimens demonstrated that markers of growth and cytoskeletal integrity (IGF-1, IGF-1 BP4, mechano growth factor, total RNA, and pro-collagen 3a) were higher in the AG group, whereas catabolic markers (myostatin and atrogen) were elevated in the C group. Importantly, these patterns were seen in both muscles. Based on these observations we conclude that paradigms of AG have the potential to maintain the functional, biochemical, and structural homeostasis of skeletal muscle in the face of chronic unloading states. These findings also warrant further studies since it is likely that other robust paradigms of AG that employ various exercise strategies may be more effective in counteracting long duration unloading states as anticipated on the platforms of the Moon and Mars.

The effect of age and unilateral leg immobilization for 2 weeks on substrate utilization during moderate‐intensity exercise in human skeletal muscle

PubMed Central

Gram, M.; Dybboe, R.; Kuhlman, A. B.; Prats, C.; Greenhaff, P. L.; Constantin‐Teodosiu, D.; Birk, J. B.; Wojtaszewski, J. F. P.; Dela, F.; Helge, J. W.

2016-01-01

Key points This study aimed to provide molecular insight into the differential effects of age and physical inactivity on the regulation of substrate metabolism during moderate‐intensity exercise.Using the arteriovenous balance technique, we studied the effect of immobilization of one leg for 2 weeks on leg substrate utilization in young and older men during two‐legged dynamic knee‐extensor moderate‐intensity exercise, as well as changes in key proteins in muscle metabolism before and after exercise.Age and immobilization did not affect relative carbohydrate and fat utilization during exercise, but the older men had higher uptake of exogenous fatty acids, whereas the young men relied more on endogenous fatty acids during exercise.Using a combined whole‐leg and molecular approach, we provide evidence that both age and physical inactivity result in intramuscular lipid accumulation, but this occurs only in part through the same mechanisms. Abstract Age and inactivity have been associated with intramuscular triglyceride (IMTG) accumulation. Here, we attempt to disentangle these factors by studying the effect of 2 weeks of unilateral leg immobilization on substrate utilization across the legs during moderate‐intensity exercise in young (n = 17; 23 ± 1 years old) and older men (n = 15; 68 ± 1 years old), while the contralateral leg served as the control. After immobilization, the participants performed two‐legged isolated knee‐extensor exercise at 20 ± 1 W (∼50% maximal work capacity) for 45 min with catheters inserted in the brachial artery and both femoral veins. Biopsy samples obtained from vastus lateralis muscles of both legs before and after exercise were used for analysis of substrates, protein content and enzyme activities. During exercise, leg substrate utilization (respiratory quotient) did not differ between groups or legs. Leg fatty acid uptake was greater in older than in young men, and although young men demonstrated net leg glycerol release during exercise, older men showed net glycerol uptake. At baseline, IMTG, muscle pyruvate dehydrogenase complex activity and the protein content of adipose triglyceride lipase, acetyl‐CoA carboxylase 2 and AMP‐activated protein kinase (AMPK)γ3 were higher in young than in older men. Furthermore, adipose triglyceride lipase, plasma membrane‐associated fatty acid binding protein and AMPKγ3 subunit protein contents were lower and IMTG was higher in the immobilized than the contralateral leg in young and older men. Thus, immobilization and age did not affect substrate choice (respiratory quotient) during moderate exercise, but the whole‐leg and molecular differences in fatty acid mobilization could explain the age‐ and immobilization‐induced IMTG accumulation. PMID:26801521

Effect of plyometric training on lower limb biomechanics in females.

PubMed

Baldon, Rodrigo de Marche; Moreira Lobato, Daniel F; Yoshimatsu, Andre P; dos Santos, Ana Flávia; Francisco, Andrea L; Pereira Santiago, Paulo R; Serrão, Fábio V

2014-01-01

To verify the effects of plyometric training on lower limb kinematics, eccentric hip and knee torques, and functional performance. Cohort study. Research laboratory. Thirty-six females were divided into a training group (TG; n = 18) that carried out the plyometric training for 8 weeks, and a control group (CG; n = 18) that carried out no physical training. Twenty-four plyometric training sessions during approximately 8 weeks with 3 sessions per week on alternate days. Lower limb kinematics (maximum excursion of hip adduction, hip medial rotation, and knee abduction during the single leg squat), eccentric hip (abductor, adductor, medial, and lateral rotator) isokinetic peak torques and knee (flexor and extensor) isokinetic peak torques, and functional performance (triple hop test and the 6-m timed hop test). After 8 weeks, only the TG significantly reduced the values for the maximum excursion of knee abduction (P = 0.01) and hip adduction (P < 0.001). Similarly, only the TG significantly increased the eccentric hip abductor (P < 0.001) and adductor (P = 0.01) torques. Finally, only the TG significantly increased the values in the triple hop test (P < 0.001) and significantly decreased the values in the 6-m timed hop test (P < 0.001) after intervention. Plyometric training alters lower limb kinematics and increases eccentric hip torque and functional performance, suggesting the incorporation of these exercises in preventive programs for ACL injuries.

A Comparison of Exercise-Induced Muscle Damage Following Maximal Eccentric Contractions in Men and Boys.

PubMed

Deli, Chariklia K; Fatouros, Ioannis G; Paschalis, Vassilis; Georgakouli, Kalliopi; Zalavras, Athanasios; Avloniti, Alexandra; Koutedakis, Yiannis; Jamurtas, Athanasios Z

2017-08-01

Research regarding exercise-induced muscle-damage mainly focuses on adults. The present study examined exercise-induced muscle-damage responses in adults compared with children. Eleven healthy boys (10-12 y) and 15 healthy men (18-45 y) performed 5 sets of 15 maximal eccentric contractions of the knee extensors. Range of motion (ROM), delayed onset muscle soreness (DOMS) during squat and walking, and peak isometric, concentric and eccentric torque were assessed before, post, 24, 48, 72, and 96 hr postexercise. Creatine kinase (CK) activity was assessed before and 72 hr postexercise. Eccentric exercise resulted in DOMS during squat that persisted for up to 96h in men, and 48 hr in boys (p < .05), and DOMS during walking that persisted for up to 72 hr in men, and 48 hr in boys (p < .01). The ROM was lower in both age groups 48 hr postexercise (p < .001). Isometric (p < .001), concentric (p < .01) and eccentric (p < .01) force decreased post, and up to 48 hr postexercise in men. Except for a reduction in isometric force immediately after exercise, no other changes occurred in boys' isokinetic force. CK activity increased in men at 72 hr postexercise compared with pre exercise levels (p = .05). Our data provide further confirmation that children are less susceptible to exercise-induced muscle damage compared with adults.

Potentiation of cGMP signaling increases oxygen delivery and oxidative metabolism in contracting skeletal muscle of older but not young humans

PubMed Central

Nyberg, Michael; Piil, Peter; Egelund, Jon; Sprague, Randy S; Mortensen, Stefan P; Hellsten, Ylva

2015-01-01

Aging is associated with progressive loss of cardiovascular and skeletal muscle function. The impairment in physical capacity with advancing age could be related to an insufficient peripheral O2 delivery to the exercising muscles. Furthermore, the mechanisms underlying an impaired blood flow regulation remain unresolved. Cyclic guanosine monophosphate (cGMP) is one of the main second messengers that mediate smooth muscle vasodilation and alterations in cGMP signaling could, therefore, be one mechanism by which skeletal muscle perfusion is impaired with advancing age. The current study aimed to evaluate the effect of inhibiting the main enzyme involved in cGMP degradation, phosphodiesterase 5 (PDE5), on blood flow and O2 delivery in contracting skeletal muscle of young and older humans. A group of young (23 ± 1 years) and a group of older (72 ± 2 years) male human subjects performed submaximal knee-extensor exercise in a control setting and following intake of the highly selective PDE5 inhibitor sildenafil. Sildenafil increased leg O2 delivery (6–9%) and leg O2 uptake (10–12%) at all three exercise intensities in older but not young subjects. The increase in leg O2 delivery with sildenafil in the older subjects correlated with the increase in leg O2 uptake (r2 = 0.843). These findings suggest an insufficient O2 delivery to the contracting skeletal muscle of aged individuals and that reduced cGMP availability is a novel mechanism underlying impaired skeletal muscle perfusion with advancing age. PMID:26272735

Discharge behavior of motor units in knee extensors during the initial stage of constant-force isometric contraction at low force level.

PubMed

Kamo, Mifuyu

2002-03-01

To elucidate the strategy of the activity of motor units (MUs) to maintain a constant-force isometric contraction, I examined the behavior of MUs in knee extensor muscles [(vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF)] during a sustained contraction at 5% of maximal voluntary contraction for 5 min. In all cases, the spike interval exhibited an elongating trend, and two discharge patterns were observed, continuous discharge and decruitment. In continuous-discharge MUs, the trend slope was steep immediately after the onset of constant force (steep phase), and then became gentle (gentle phase). Decruitments were observed frequently during each phase, and additional MU recruitment was observed throughout the contraction. The mean value of recruitment threshold force did not differ among the extensors. The mean spike interval at the onset of constant-force isometric contractions was shorter in RF than in VL. However, there were no differences in the duration and extent of the elongating trend, decruitment time and recruitment time among the extensors. The electromyogram of the antagonist biceps femoris muscle revealed no compensatory change for extensor activity. These results indicated that at a low force level, the strategy employed by the central nervous system to maintain constant force appears to involve cooperation among elongating trends in the spike interval, decruitment following elongation, and additional MU recruitment in synergistic muscles.

Muscle fatigue during intermittent exercise in individuals with mental retardation.

PubMed

Zafeiridis, Andreas; Giagazoglou, Paraskevi; Dipla, Konstantina; Salonikidis, Konstantinos; Karra, Chrisanthi; Kellis, Eleftherios

2010-01-01

This study examined fatigue profile during intermittent exercise in 10 men with mild to moderate mental retardation (MR) and 10 men without mental retardation (C). They performed 4 x 30s maximal knee extensions and flexions with 1-min rest on an isokinetic dynamometer. Peak torque of flexors (PTFL) and extensors (PTEX), total work (TW), and lactate were measured. Fatigue was calculated as the magnitude of decline (%) in PTFL, PTEX, and TW and as rate of decline (linear slope) in TW from 1st to 4th set. MR had lower PTFL, PTEX, TW, and lactate throughout the protocol than C, while pre-motor time was greater in MR vs. C (p<0.05). MR demonstrated a delayed pattern of reduction in muscular performance. Lower values were observed in MR vs. C in the magnitude of decline for PTEX and TW and the rate of decline for TW. In conclusion, MR exhibit a different fatigue profile during intermittent exercise than C. The lower magnitude and decline rate in neuromuscular performance in MR during intermittent exercise is associated with their lower peak strength, short-term anaerobic capacity, and lactate accumulation. Rehabilitation and sport professionals should consider the differences in fatigue profile when designing intermittent exercise programs for MR. Copyright 2009 Elsevier Ltd. All rights reserved.

Gait perturbation response in chronic anterior cruciate ligament deficiency and repair.

PubMed

Ferber, Reed; Osternig, Louis R; Woollacott, Marjorie H; Wasielewski, Noah J; Lee, Ji Hang

2003-02-01

To determine how chronic anterior cruciate ligament deficient and surgically repaired subjects react to unexpected forward perturbations during gait as compared to healthy controls. Gait testing of 10 chronic anterior cruciate ligament deficient subjects prior to and three months following reconstructive surgery, and 10 uninjured controls. The ability of an anterior cruciate ligament injured individual to react and maintain equilibrium during gait perturbations is critical for the prevention of reinjury. No studies have investigated how these individuals respond to unexpected perturbations during normal gait. An unexpected forward perturbation was induced upon heel strike using a force plate capable of translational movement. Prior to surgery, the anterior cruciate ligament subjects exhibited a greater knee extensor moment in response to the perturbation compared to healthy controls. Following surgery, the anterior cruciate ligament injured subjects exhibited a static knee position and a sustained knee extensor moment throughout stance in response to the perturbation as compared to controls. These data suggest that chronic anterior cruciate ligament deficient subjects rely heavily on knee extensor musculature to prevent collapse in response to an unexpected perturbation. This same reactive response was more pronounced 3 months following surgery. The results suggest that, prior to and following surgery, chronic anterior cruciate ligament injured subjects respond differently than healthy controls to an unexpected perturbation during gait. Anterior cruciate ligament injured or repaired subjects do not reduce or avoid vigorous contraction of the quadriceps muscles when responding to gait perturbations.

Physical performance measures that predict faller status in community-dwelling older adults.

PubMed

Macrae, P G; Lacourse, M; Moldavon, R

1992-01-01

Falls are a leading cause of fatal and nonfatal injuries among the elderly. Accurate determination of risk factors associated with falls in older adults is necessary, not only for individual patient management, but also for the development of fall prevention programs. The purpose of this study was to evaluate the effectiveness of clinical measures, such as the one-legged stance test (OLST), sit-to-stand test (STST), manual muscle tests (MMT), and response speed in predicting faller status in community-dwelling older adults (N = 94, age 60-89 years). The variables assessed were single-leg standing (as measured by OLST), STST, and MMT of 12 different muscle groups (hip flexors, hip abductors, hip adductors, knee flexors, knee extensors, ankle dorsiflexors, ankle plantarflexors, shoulder flexors, shoulder abductors, elbow flexors, elbow extensors, and finger flexors), and speed of response (as measured by a visual hand reaction and movement time task). Of the 94 older adults assessed, 28 (29.7%) reported at least one fall within the previous year. The discriminant analysis revealed that there were six variables that significantly discriminated between fallers and nonfallers. These variables included MMT of the ankle dorsiflexors, knee flexors, hip abductors, and knee extensors, as well as time on the OLST and the STST. The results indicate that simple clinical measures of musculoskeletal function can discriminate fallers from nonfallers in community-dwelling older adults. J Orthop Sports Phys Ther 1992;16(3):123-128.

Evaluation of peripheral muscle strength of patients undergoing elective cardiac surgery: a longitudinal study

PubMed Central

Santos, Kelli Maria Souza; de Cerqueira Neto, Manoel Luiz; Carvalho, Vitor Oliveira; de Santana Filho, Valter Joviniano; da Silva Junior, Walderi Monteiro; Araújo Filho, Amaro Afrânio; Cerqueira, Telma Cristina Fontes; Cacau, Lucas de Assis Pereira

2014-01-01

Introduction Peripheral muscle strength has been little explored in the literature in the context of cardiac rehabilitation. Objective To evaluate the peripheral muscle strength of patients undergoing elective cardiac surgery. Methods This was a longitudinal observational study. The peripheral muscle strength was measured using isometric dynamometry lower limb (knee extensors and flexors) at three different times: preoperatively (M1), the day of discharge (M2) and hospital discharge (M3). Participants received physiotherapy pre and postoperatively during the days of hospitalization during the morning and afternoon. Results Twenty-two patients were evaluated. The values of peripheral muscle strength of knee extensors preoperative found were about 50% lower than those predicted for the healthy population. When comparing muscle strength prior (M1), with the remaining evaluation, found himself in a fall of 29% for the movement of knee extension and 25% for knee flexion in M2 and a decrease of 10% movement for knee extension and 13% for knee flexion in M3 when comparing with M1. Conclusion The values of peripheral muscle strength prior of the study patients were lower than predicted for the healthy population of the same age. After the surgical event this reduction is even more remarkable, being reestablished until the time of discharge, to values close to baseline. PMID:25372909

Evaluation of peripheral muscle strength of patients undergoing elective cardiac surgery: a longitudinal study.

PubMed

Santos, Kelli Maria Souza; Cerqueira Neto, Manoel Luiz de; Carvalho, Vitor Oliveira; Santana Filho, Valter Joviniano de; Silva Junior, Walderi Monteiro da; Araújo Filho, Amaro Afrânio; Cerqueira, Telma Cristina Fontes; Cacau, Lucas de Assis Pereira

2014-01-01

Peripheral muscle strength has been little explored in the literature in the context of cardiac rehabilitation. To evaluate the peripheral muscle strength of patients undergoing elective cardiac surgery. This was a longitudinal observational study. The peripheral muscle strength was measured using isometric dynamometry lower limb (knee extensors and flexors) at three different times: preoperatively (M1), the day of discharge (M2) and hospital discharge (M3). Participants received physiotherapy pre and postoperatively during the days of hospitalization during the morning and afternoon. Twenty-two patients were evaluated. The values of peripheral muscle strength of knee extensors preoperative found were about 50% lower than those predicted for the healthy population. When comparing muscle strength prior (M1), with the remaining evaluation, found himself in a fall of 29% for the movement of knee extension and 25% for knee flexion in M2 and a decrease of 10% movement for knee extension and 13% for knee flexion in M3 when comparing with M1. The values of peripheral muscle strength prior of the study patients were lower than predicted for the healthy population of the same age. After the surgical event this reduction is even more remarkable, being reestablished until the time of discharge, to values close to baseline.

Sex differences in neuromuscular fatigability in response to load carriage in the field in British Army recruits.

PubMed

O'Leary, Thomas J; Saunders, Samantha C; McGuire, Stephen J; Izard, Rachel M

2018-06-01

Women are resistant to neuromuscular fatigue compared to men in response to a range of exercise tasks. The sex differences in the neuromuscular responses to load carriage have yet to be investigated. Prospective cohort study. Twenty-three male and 19 female British Army recruits completed a 9.7km loaded march within 90min, with the weight carried dependent on military trade (16±2kg for men and 15±1kg for women). Isometric maximal voluntary contraction (MVC) force of the knee extensors and vertical jump (VJ) height were examined pre- and post-loaded march to examine neuromuscular fatigue. Heart rate (HR) was recorded throughout and ratings of perceived exertion (RPE) was recorded following the march. HR was higher for women (173±9bmin -1 , 83±6% heart rate reserve) than men (158±8bmin -1 , 72±6% heart rate reserve) (p≤0.001). RPE following the march was also higher for women than men (6±2 vs 4±2, respectively, p<0.001). The loss in MVC force was greater for men than women (-12±9% vs -9±13%, respectively, p=0.031), however VJ height was impaired to a similar extent (-5±11% vs -5±6%, respectively, p=0.582). The greater physiological stress during load carriage for women compared to men did not translate to a greater severity of knee extensor muscle fatigue, with women demonstrating fatigue resistance. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

A methodologic approach for normalizing angular work and velocity during isotonic and isokinetic eccentric training.

PubMed

Guilhem, Gaël; Cornu, Christophe; Guével, Arnaud

2012-01-01

Resistance exercise training commonly is performed against a constant external load (isotonic) or at a constant velocity (isokinetic). Researchers comparing the effectiveness of isotonic and isokinetic resistance-training protocols need to equalize the mechanical stimulus (work and velocity) applied. To examine whether the standardization protocol could be adjusted and applied to an eccentric training program. Controlled laboratory study. Controlled research laboratory. Twenty-one sport science male students (age = 20.6 ± 1.5 years, height = 178.0 ± 4.0 cm, mass = 74.5 ± 9.1 kg). Participants performed 9 weeks of isotonic (n = 11) or isokinetic (n = 10) eccentric training of knee extensors that was designed so they would perform the same amount of angular work at the same mean angular velocity. Angular work and angular velocity. The isotonic and isokinetic groups performed the same total amount of work (-185.2 ± 6.5 kJ and -184.4 ± 8.6 kJ, respectively) at the same angular velocity (21 ± 1°/s and 22°/s, respectively) with the same number of repetitions (8.0 and 8.0, respectively). Bland-Altman analysis showed that work (bias = 2.4%) and angular velocity (bias = 0.2%) were equalized over 9 weeks between the modes of training. The procedure developed allows angular work and velocity to be standardized over 9 weeks of isotonic and isokinetic eccentric training of the knee extensors. This method could be useful in future studies in which researchers compare neuromuscular adaptations induced by each type of training mode with respect to rehabilitating patients after musculoskeletal injury.

Effects of barbell deadlift training on submaximal motor unit firing rates for the vastus lateralis and rectus femoris.

PubMed

Stock, Matt S; Thompson, Brennan J

2014-01-01

Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units.

Voluntary Movement Frequencies in Submaximal One- and Two-Legged Knee Extension Exercise and Pedaling

PubMed Central

Stang, Julie; Wiig, Håvard; Hermansen, Marte; Hansen, Ernst Albin

2016-01-01

Understanding of behavior and control of human voluntary rhythmic stereotyped leg movements is useful in work to improve performance, function, and rehabilitation of exercising, healthy, and injured humans. The present study aimed at adding to the existing understanding within this field. To pursue the aim, correlations between freely chosen movement frequencies in relatively simple, single-joint, one- and two-legged knee extension exercise were investigated. The same was done for more complex, multiple-joint, one- and two-legged pedaling. These particular activities were chosen because they could be considered related to some extent, as they shared a key aspect of knee extension, and because they at the same time were different. The activities were performed at submaximal intensities, by healthy individuals (n = 16, thereof eight women; 23.4 ± 2.7 years; 1.70 ± 0.11 m; 68.6 ± 11.2 kg). High and fair correlations (R-values of 0.99 and 0.75) occurred between frequencies generated with the dominant leg and the nondominant leg during knee extension exercise and pedaling, respectively. Fair to high correlations (R-values between 0.71 and 0.95) occurred between frequencies performed with each of the two legs in an activity, and the two-legged frequency performed in the same type of activity. In general, the correlations were higher for knee extension exercise than for pedaling. Correlations between knee extension and pedaling frequencies were of modest occurrence. The correlations between movement frequencies generated separately by each of the legs might be interpreted to support the following working hypothesis, which was based on existing literature. It is likely that involved central pattern generators (CPGs) of the two legs share a common frequency generator or that separate frequency generators of each leg are attuned via interneuronal connections. Further, activity type appeared to be relevant. Thus, the apparent common rhythmogenesis for the two legs appeared to be stronger for the relatively simple single-joint activity of knee extension exercise as compared to the more complex multi-joint activity of pedaling. Finally, it appeared that the shared aspect of knee extension in the related types of activities of knee extension exercise and pedaling was insufficient to cause obvious correlations between generated movement frequencies in the two types of activities. PMID:26973486

Fatigue reduction during aggregated and distributed sequential stimulation.

PubMed

Bergquist, Austin J; Babbar, Vishvek; Ali, Saima; Popovic, Milos R; Masani, Kei

2017-08-01

Transcutaneous neuromuscular electrical stimulation (NMES) can generate muscle contractions for rehabilitation and exercise. However, NMES-evoked contractions are limited by fatigue when they are delivered "conventionally" (CONV) using a single active electrode. Researchers have developed "sequential" (SEQ) stimulation, involving rotation of pulses between multiple "aggregated" (AGGR-SEQ) or "distributed" (DISTR-SEQ) active electrodes, to reduce fatigue (torque-decline) by reducing motor unit discharge rates. The primary objective was to compare fatigue-related outcomes, "potentiation," "variability," and "efficiency" between CONV, AGGR-SEQ, and DISTR-SEQ stimulation of knee extensors in healthy participants. Torque and current were recorded during testing with fatiguing trains using each NMES type under isometric and isokinetic (180°/s) conditions. Compared with CONV stimulation, SEQ techniques reduced fatigue-related outcomes, increased potentiation, did not affect variability, and reduced efficiency. SEQ techniques hold promise for reducing fatigue during NMES-based rehabilitation and exercise; however, optimization is required to improve efficiency. Muscle Nerve 56: 271-281, 2017. © 2016 Wiley Periodicals, Inc.

Muscle-Specific Effective Mechanical Advantage and Joint Impulse in Weightlifting.

PubMed

Kipp, Kristof; Harris, Chad

2017-07-01

Kipp, K, and Harris, C. Muscle-specific effective mechanical advantage and joint impulse in weightlifting. J Strength Cond Res 31(7): 1905-1910, 2017-Lifting greater loads during weightlifting exercises may theoretically be achieved through increasing the magnitudes of net joint impulses or manipulating the joints' effective mechanical advantage (EMA). The purpose of this study was to investigate muscle-specific EMA and joint impulse as well as impulse-momentum characteristics of the lifter-barbell system across a range of external loads during the execution of the clean. Collegiate-level weightlifters performed submaximal cleans at 65, 75, and 85% of their 1-repetition maximum (1-RM), whereas data from a motion analysis system and a force plate were used to calculate lifter-barbell system impulse and velocity, as well as net extensor impulse generated at the hip, knee, and ankle joints and the EMA of the gluteus maximus, hamstrings, quadriceps, and triceps surae muscles. The results indicated that the lifter-barbell system impulse did not change as load increased, whereas the velocity of the lifter-barbell system decreased with greater load. In addition, the net extensor impulse at all joints increased as load increased. The EMA of all muscles did not, however, change as load increased. The load-dependent effects on the impulse-velocity characteristics of the lifter-barbell system may reflect musculoskeletal force-velocity behaviors, and may further indicate that the weightlifting performance is limited by the magnitude of ground reaction force impulse. In turn, the load-dependent effects observed at the joint level indicated that lifting greater loads were due to greater net extensor impulses generated at the joints of the lower extremity and not greater EMAs of the respective extensor muscles. In combination, these results suggest that lifting greater external loads during the clean is due to the ability to generate large extensor joint impulses, rather than manipulate EMA.

A SIX-WEEK SUPERVISED EXERCISE AND EDUCATIONAL INTERVENTION AFTER TOTAL HIP ARTHROPLASTY: A CASE SERIES

PubMed Central

Madara, Kathleen; Zeni, Joseph A

2017-01-01

Background and Purpose Most rehabilitation interventions after total hip arthroplasty (THA) are not designed to return patients to high-levels of physical activity and, thus, low levels of physical activity and residual weakness are common. The purpose of this case series was to describe the feasibility and preliminary efficacy of an exercise and education intervention for patients after THA who have already completed formal outpatient physical therapy. Study Design Case series Case Description Two participants underwent unilateral THA seven (case A) or eight (case B) months prior to the intervention. Individuals participated in 18 treatment sessions that included progressive aerobic and strengthening exercises and meetings with a health coach. Change in function, strength, and self-reported physical activity were measured. Outcomes 12 months after surgery were compared to a historical cohort of patients after THA. Outcome There were no adverse events during the intervention. At the end of the intervention, hip and knee strength on the surgical side increased approximately 30% compared to baseline in both cases. Activity level, and recreational performance, including walking up stairs and hiking uphill (case A), and running and golfing (case B), improved by the end of the intervention. Most changes were maintained at follow-up, although hip strength for case B decreased 27% after discharge from the intervention. Outcomes for both cases exceeded historical averages for patients 12 months after THA, with the exception of strength in case B. Discussion The exercise intervention was well tolerated and without negative effects in two participants. Both participants increased their ability to complete demanding recreational and sports-related activities, physical activity, and demonstrated improved hip abductor and knee extensor strength. Further research is needed to evaluate the implementation and effectiveness of similar interventions after THA. Level of Evidence Level 4 PMID:28515981

Weightlifting performance is related to kinematic and kinetic patterns of the hip and knee joints.

PubMed

Kipp, Kristof; Redden, Josh; Sabick, Michelle B; Harris, Chad

2012-07-01

The purpose of this study was to investigate the correlations between biomechanical outcome measures and weightlifting performance. Joint kinematics and kinetics of the hip, knee, and ankle were calculated while 10 subjects performed a clean at 85% of 1 repetition maximum (1RM). Kinematic and kinetic time-series patterns were extracted with principal components analysis. Discrete scores for each time-series pattern were calculated and used to determine how each pattern was related to body mass-normalized 1RM. Two hip kinematic and 2 knee kinetic patterns were significantly correlated with relative 1RM. The kinematic patterns captured hip and trunk motions during the first pull and hip joint motion during the movement transition between the first and second pulls. The first kinetic pattern captured a peak in the knee extension moment during the second pull. The second kinetic pattern captured a spatiotemporal shift in the timing and amplitude of the peak knee extension moment. The kinematic results suggest that greater lift mass was associated with steady trunk position during the first pull and less hip extension motion during the second-knee bend transition. Further, the kinetic results suggest that greater lift mass was associated with a smaller knee extensor moments during the first pull, but greater knee extension moments during the second pull, and an earlier temporal transition between knee flexion-extension moments at the beginning of the second pull. Collectively, these results highlight the importance of controlled trunk and hip motions during the first pull and rapid employment of the knee extensor muscles during the second pull in relation to weightlifting performance.

Effects of Step Length, Age, and Fall History on Hip and Knee Kinetics and Knee Co-contraction during the Maximum Step Length Test

PubMed Central

Schulz, Brian W.; Jongprasithporn, Manutchanok; Hart-Hughes, Stephanie J.; Bulat, Tatjana

2017-01-01

Background Maximum step length is a brief clinical test involving stepping out and back as far as possible with the arms folded across the chest. This test has been shown to predict fall risk, but the biomechanics of this test are not fully understood. Knee and hip kinetics (moments and powers) are greater for longer steps and for younger subjects, but younger subjects also step farther. Methods To separate effects of step length, age, and fall history on joint kinetics; 14 healthy younger, 14 older non-fallers, and 11 older fallers (27(5), 72(5), 75(6) years respectively) all stepped to the same relative target distances of 20-80% of their height. Knee and hip kinetics and knee co-contraction were calculated. Findings Hip and knee kinetics and knee co-contraction all increased with step length, but older non-fallers and fallers utilized greater stepping hip and less stepping knee extensor kinetics. Fallers had greater stepping knee co-contraction than non-fallers. Stance knee co-contraction of non-fallers was similar to young for shorter steps and similar to fallers for longer steps. Interpretation Age had minimal effects and fall history had no effects on joint kinetics of steps to similar distances. Effects of age and fall history on knee co-contraction may contribute to age-related kinetic differences and shorter maximal step lengths of older non-fallers and fallers, but step length correlated with every variable tested. Thus, declines in maximum step length could indicate declines in hip and knee extensor kinetics and impaired performance on similar tasks like recovering from a trip. PMID:23978310

INTENSITY, DURATION AND TYPE OF PHYSICAL ACTIVITY REQUIRED TO IMPROVE FUNCTION IN KNEE OSTEOARTHRITIS

PubMed Central

KIRIHARA, RICARDO AKIHIRO; CATELAN, FELLIPE BRAVIM; FARIAS, FABIANE ELIZE SABINO DE; SILVA, CLEIDNÉIA APARECIDA CLEMENTE DA; CERNIGOY, CLAUDIA HELENA DE AZEVEDO; REZENDE, MÁRCIA UCHOA DE

2017-01-01

ABSTRACT Objective: To evaluate the effects of physical activity intensity, type and duration in patients with knee osteoarthritis (KOA). Methods: A retrospective study of 195 KOA patients who were followed for two years after receiving educational material about KOA with or without attending classes. The patients were evaluated at baseline and 24 months. At the evaluations, the patients answered questionnaires pertaining to pain and function (WOMAC, Lequesne, VAS and SF-36); reported the intensity, duration and type of exercise performed per week; and performed the Timed Up & Go (TUG) and Five Times Sit-to-Stand (FTSST) tests. Results: Increased age affected improvements in the TUG results (p=0.017). The type, intensity and duration of physical activity did not correlate with pain, function or quality of life improvements (p>0.05), but the TUG results were on average 4 seconds faster among the patients who practiced intense physical activity and/or exercised for more than 180 minutes per week and/or performed isolated weight training or swam compared with those who remained sedentary after 2 years (p=0.01; p<0.001; p=0.01; p=0.04, respectively). Conclusions: Patients with KOA should aim for intense physical activity and/or more than 180 minutes of exercise per week and/or weight training (bodybuilding) for relevant pain reduction and functional improvement.Level of Evidence II, Retrospective Study. PMID:28642646

The effects of different durations of static stretching within a comprehensive warm-up on voluntary and evoked contractile properties.

PubMed

Reid, Jonathan C; Greene, Rebecca; Young, James D; Hodgson, Daniel D; Blazevich, Anthony J; Behm, David G

2018-05-02

Evidence for performance decrements following prolonged static stretching (SS) has led to a paradigm shift in stretching routines within a warm-up. Rather than SS, dynamic stretching (DS) and dynamic activity (DA) have replaced SS within warm-up routines. The objective of the present study was to compare the effect of differing lower limb SS durations (30 [SS30s], 60 [SS60s] or 120 s [SS120s] of SS per muscle group or no-stretch control) within a comprehensive warm-up protocol consisting of aerobic activity, DS and DA. Sixteen male participants completed the four stretching conditions in a randomized order, after a 5-min low-intensity (cycle) warm-up and before a DS/DA component on separate days. Tests included passive hip and knee ranges of motion (ROM), maximum voluntary knee extensor/flexor force, force produced at 100 ms (F100), vertical jump height and evoked knee extensor contractile properties. For hip flexion (hamstrings) ROM, SS120s provided the largest increase (5.6-11.7%) followed by SS60s (4.3-11.4%), control (4.4-10.6%) and SS30s (3.6-11.1%). For knee flexion (quadriceps) ROM, SS30s provided the largest increase (9.3-18.2%) followed by SS120s (6.5-16.3%), SS60s (7.2-15.2%) and control (6.3-15.2%). There were decreases in quadriceps F100 following SS in SS120s (29.6%) only. There were increases in vertical jump performance in the control (6.2%), SS60s (4.6%) and SS30s (3.3%). While 120 s SS per muscle increased ROM, even within a comprehensive warm-up routine, it also elicited notable performance decrements. However, moderate durations of SS were observed to improve ROM whilst either having negligible or beneficial (but not detrimental) effects on specific aspects of athletic performance.

Is high-intensity interval cycling feasible and more beneficial than continuous cycling for knee osteoarthritic patients? Results of a randomised control feasibility trial

PubMed Central

Grigg, Josephine

2018-01-01

Background Knee osteoarthritis (OA) patients often suffer joint pain and stiffness, which contributes to negative changes in body composition, strength, physical performance (function), physical activity and health-related quality of life. To reduce these symptoms and side effects of knee OA, moderate-intensity continuous training (MICT) cycling is often recommended. While resistance training is considered the optimal form of training to improve sarcopenic outcomes, it imposes higher joint loads and requires supervision, either initially or continuously by trained exercise professionals. Therefore, this pilot study sought to gain some insight into the feasibility and potential benefits of high-intensity interval training (HIIT) cycling as an alternative exercise option to MICT cycling for individuals with knee OA. Methods Twenty-seven middle-aged and older adults with knee OA were randomly allocated to either MICT or HIIT, with both programs involving four unsupervised home-based cycling sessions (∼25 min per session) each week for eight weeks. Feasibility was assessed by enrolment rate, withdrawal rate, exercise adherence and number of adverse effects. Efficacy was assessed by health-related quality of life (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Lequesne index), physical function (Timed Up and Go (TUG), Sit to Stand (STS) and preferred gait speed) and body composition (body mass, BMI, body fat percentage and muscle mass). Results Twenty-seven of the interested 50 potential participants (54%) enrolled in the study, with 17 of the 27 participants completing the trial (withdrawal rate of 37%); with the primary withdrawal reasons being unrelated injuries or illness or family related issues. Of the 17 participants who completed the trial, exercise adherence was very high (HIIT 94%; MICT 88%). While only three individuals (one in the MICT and two in the HIIT group) reported adverse events, a total of 28 adverse events were reported, with 24 of these attributed to one HIIT participant. Pre–post-test analyses indicated both groups significantly improved their WOMAC scores, with the HIIT group also significantly improving in the TUG and STS. The only significant between-group difference was observed in the TUG, whereby the HIIT group improved significantly more than the MICT group. No significant changes were observed in the Lequesne index, gait speed or body composition for either group. Discussion An unsupervised home-based HIIT cycle program appears somewhat feasible for middle-aged and older adults with knee OA and may produce similar improvements in health-related quality of life but greater improvements in physical function than MICT. These results need to be confirmed in larger randomised controlled trials to better elucidate the potential for HIIT to improve outcomes for those with knee OA. Additional research needs to identify and modify the potential barriers affecting the initiation and adherence to home-based HIIT cycling exercise programs by individuals with knee OA. PMID:29761054

Is high-intensity interval cycling feasible and more beneficial than continuous cycling for knee osteoarthritic patients? Results of a randomised control feasibility trial.

PubMed

Keogh, Justin W; Grigg, Josephine; Vertullo, Christopher J

2018-01-01

Knee osteoarthritis (OA) patients often suffer joint pain and stiffness, which contributes to negative changes in body composition, strength, physical performance (function), physical activity and health-related quality of life. To reduce these symptoms and side effects of knee OA, moderate-intensity continuous training (MICT) cycling is often recommended. While resistance training is considered the optimal form of training to improve sarcopenic outcomes, it imposes higher joint loads and requires supervision, either initially or continuously by trained exercise professionals. Therefore, this pilot study sought to gain some insight into the feasibility and potential benefits of high-intensity interval training (HIIT) cycling as an alternative exercise option to MICT cycling for individuals with knee OA. Twenty-seven middle-aged and older adults with knee OA were randomly allocated to either MICT or HIIT, with both programs involving four unsupervised home-based cycling sessions (∼25 min per session) each week for eight weeks. Feasibility was assessed by enrolment rate, withdrawal rate, exercise adherence and number of adverse effects. Efficacy was assessed by health-related quality of life (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Lequesne index), physical function (Timed Up and Go (TUG), Sit to Stand (STS) and preferred gait speed) and body composition (body mass, BMI, body fat percentage and muscle mass). Twenty-seven of the interested 50 potential participants (54%) enrolled in the study, with 17 of the 27 participants completing the trial (withdrawal rate of 37%); with the primary withdrawal reasons being unrelated injuries or illness or family related issues. Of the 17 participants who completed the trial, exercise adherence was very high (HIIT 94%; MICT 88%). While only three individuals (one in the MICT and two in the HIIT group) reported adverse events, a total of 28 adverse events were reported, with 24 of these attributed to one HIIT participant. Pre-post-test analyses indicated both groups significantly improved their WOMAC scores, with the HIIT group also significantly improving in the TUG and STS. The only significant between-group difference was observed in the TUG, whereby the HIIT group improved significantly more than the MICT group. No significant changes were observed in the Lequesne index, gait speed or body composition for either group. An unsupervised home-based HIIT cycle program appears somewhat feasible for middle-aged and older adults with knee OA and may produce similar improvements in health-related quality of life but greater improvements in physical function than MICT. These results need to be confirmed in larger randomised controlled trials to better elucidate the potential for HIIT to improve outcomes for those with knee OA. Additional research needs to identify and modify the potential barriers affecting the initiation and adherence to home-based HIIT cycling exercise programs by individuals with knee OA.

Thirty Minutes of Running Exercise Decreases T2 Signal Intensity but Not Thickness of the Knee Joint Cartilage: A 3.0-T Magnetic Resonance Imaging Study.

PubMed

Karanfil, Yiğitcan; Babayeva, Naila; Dönmez, Gürhan; Diren, H Barış; Eryılmaz, Muzaffer; Doral, Mahmut Nedim; Korkusuz, Feza

2018-04-01

Objective Recent studies showed a potential of magnetic resonance imaging (MRI), which can be used as an additional tool for diagnosing cartilage degeneration in the early stage. We designed a cross-sectional study in order to evaluate knee joint cartilage adaptation to running, using 3.0-T MRI equipped with the 3-dimensional turbo spin echo (VISTA = Volume ISotropic Turbo spin echo Acquisition) software. By this thickness (mm) and signal intensity (mean pixel value) can be quantified, which could be closely related to the fluid content of the knee joint cartilage, before and after running. Methods A total of 22 males, aged 18 to 35 years, dominant (right) and nondominant (left) knees were assessed before and after 30 minutes of running. Cartilage thickness and signal intensity of surfaces of the patella, medial and lateral femoral and tibial condyles were measured. Results Cartilage thickness of the lateral condyle decreased at the dominant knee, while it increased at the medial tibial plateau. Signal intensity decreased at all locations, except the lateral patella in both knees. The most obvious decrease in signal intensity (10.6%) was at the medial tibial plateau from 949.8 to 849.0 of the dominant knee. Conclusion There was an increase in thickness measurements and decrease in signal intensity in medial tibial plateau of the dominant knee after 30 minutes of running. This outcome could be related to fluid outflow from the tissue. Greater reductions in the medial tibial plateau cartilage indicate greater load sharing by these areas of the joint during a 30-minute running.

Effect of knee flexion angle on ground reaction forces, knee moments and muscle co-contraction during an impact-like deceleration landing: implications for the non-contact mechanism of ACL injury.

PubMed

Podraza, Jeffery T; White, Scott C

2010-08-01

Investigating landing kinetics and neuromuscular control strategies during rapid deceleration movements is a prerequisite to understanding the non-contact mechanism of ACL injury. The purpose of this study was to quantify the effect of knee flexion angle on ground reaction forces, net knee joint moments, muscle co-contraction and lower extremity muscles during an impact-like, deceleration task. Ground reaction forces and knee joint moments were determined from video and force plate records of 10 healthy male subjects performing rapid deceleration single leg landings from a 10.5 cm height with different degrees of knee flexion at landing. Muscle co-contraction was based on muscle moments calculated from an EMG-to-moment processing model. Ground reaction forces and co-contraction indices decreased while knee extensor moments increased significantly with increased degrees of knee flexion at landing (all p<0.005). Higher ground reaction forces when landing in an extended knee position suggests they are a contributing factor in non-contact ACL injuries. Increased knee extensor moments and less co-contraction with flexed knee landings suggest that quadriceps overload may not be the primary cause of non-contact ACL injuries. The results bring into question the counterbalancing role of the hamstrings during dynamic movements. The soleus may be a valuable synergist stabilizing the tibia against anterior translation at landing. Movement strategies that lessen the propagation of reaction forces up the kinetic chain may help prevent non-contact ACL injuries. The relative interaction of all involved thigh and lower leg muscles, not just the quadriceps and hamstrings should be considered when interpreting non-contact ACL injury mechanisms. Copyright 2010 Elsevier B.V. All rights reserved.

Different knee joint loading patterns in ACL deficient copers and non-copers during walking.

PubMed

Alkjær, Tine; Henriksen, Marius; Simonsen, Erik B

2011-04-01

Rupture of the anterior cruciate ligament (ACL) causes changes in the walking pattern. ACL deficient subjects classified as copers and non-copers have been observed to adopt different post-injury walking patterns. How these different patterns affect the knee compression and shear forces is unresolved. Thus, the aim of the present study was to investigate how different walking patterns observed between copers, non-copers, and controls affect the knee compression and shear forces during walking. Three-dimensional gait analyses were performed in copers (n = 9), non-copers (n = 10), and control subjects (n =19). The net knee joint moment, knee joint reaction forces, and the sagittal knee joint angle were input parameters to a biomechanical model that assessed the knee compression and shear forces. The results showed that the non-copers walked with significantly reduced knee compression and shear forces than the controls. The overall knee compression force pattern was similar between the copers and controls, although this variable was significantly increased at heel strike in the copers compared to both non-copers and controls. The peak shear force was significantly dependent on the peak knee extensor moment. This covariance was significantly different between groups meaning that at a given knee extensor moment the shear force was significantly reduced in the copers compared to controls. The different knee joint loading patterns observed between non-copers and copers reflected the different walking strategies adopted by these groups, which may have implications for the knee joint stability. The strategy adopted by the copers may resemble an effective way to stabilize the knee joint during walking after an ACL rupture and that the knee kinematics may play a key role for this strategy. It is clinically relevant to investigate if gait retraining would enable non-copers to walk as copers and thereby improve their knee joint stability.

Effects of a progressive resistance exercise program with high-speed component on the physical function of older women with sarcopenic obesity: a randomized controlled trial.

PubMed

Vasconcelos, Karina S S; Dias, João M D; Araújo, Marília C; Pinheiro, Ana C; Moreira, Bruno S; Dias, Rosângela C

2016-07-11

Sarcopenic obesity is associated with disability in older people, especially in women. Resistance exercises are recommended for this population, but their efficacy is not clear. To evaluate the effects of a progressive resistance exercise program with high-speed component on the physical function of older women with sarcopenic obesity. Twenty-eight women 65 to 80 years old, with a body mass index ≥30kg/m2 and handgrip strength ≤21kg were randomly allocated to two groups. The experimental group underwent a 10-week resistance exercise program designed to improve strength, power, and endurance of lower-limb muscles, with open chain and closed chain exercises. The control group had their health status monitored through telephone calls. The primary outcomes were lower limb muscle performance measured by knee extensor strength, power and fatigue by isokinetic dynamometry, and mobility measured by the Short Physical Performance Battery and by gait velocity. The secondary outcome was health-related quality of life assessed by the SF-36 Questionnaire. The average rate of adherence was 85%, with few mild adverse effects. There were no significant between-group differences for any of the outcomes. In this study, a progressive resistance exercise program with high-speed component was not effective for improving the physical function of older women with sarcopenic obesity.

Resistance training using eccentric overload induces early adaptations in skeletal muscle size.

PubMed

Norrbrand, Lena; Fluckey, James D; Pozzo, Marco; Tesch, Per A

2008-02-01

Fifteen healthy men performed a 5-week training program comprising four sets of seven unilateral, coupled concentric-eccentric knee extensions 2-3 times weekly. While eight men were assigned to training using a weight stack (WS) machine, seven men trained using a flywheel (FW) device, which inherently provides variable resistance and allows for eccentric overload. The design of these apparatuses ensured similar knee extensor muscle use and range of motion. Before and after training, maximal isometric force (MVC) was measured in tasks non-specific to the training modes. Volume of all individual quadriceps muscles was determined by magnetic resonance imaging. Performance across the 12 exercise sessions was measured using the inherent features of the devices. Whereas MVC increased (P < 0.05) at all angles measured in FW, such a change was less consistent in WS. There was a marked increase (P < 0.05) in task-specific performance (i.e., load lifted) in WS. Average work showed a non-significant 8.7% increase in FW. Quadriceps muscle volume increased (P < 0.025) in both groups after training. Although the more than twofold greater hypertrophy evident in FW (6.2%) was not statistically greater than that shown in WS (3.0%), all four individual quadriceps muscles of FW showed increased (P < 0.025) volume whereas in WS only m. rectus femoris was increased (P < 0.025). Collectively the results of this study suggest more robust muscular adaptations following flywheel than weight stack resistance exercise supporting the idea that eccentric overload offers a potent stimuli essential to optimize the benefits of resistance exercise.

Effects of exercise-induced muscle damage on resting metabolic rate, sub-maximal running and post-exercise oxygen consumption.

PubMed

Burt, Dean Gareth; Lamb, Kevin; Nicholas, Ceri; Twist, Craig

2014-01-01

Exercise-induced muscle damage (EIMD), described as the acute weakness of the musculature after unaccustomed eccentric exercise, increases oxidative metabolism at rest and during endurance exercise. However, it is not known whether oxygen uptake during recovery from endurance exercise is increased when experiencing symptoms of EIMD. Therefore, the purpose of this study was to investigate the effects of EIMD on physiological and metabolic responses before, during and after sub-maximal running. After a 12 h fast, eight healthy male participants completed baseline measurements comprising resting metabolic rate (RMR), indirect markers of EIMD, 10 min of sub-maximal running and 30 min of recovery to ascertain excess post-exercise oxygen consumption (EPOC). Measurements were then repeated at 24 and 48 h after 100 Smith-machine squats. Data analysis revealed significant (P<0.05) increases in muscle soreness and creatine kinase (CK) and decreases in peak knee extensor torque at 24 and 48 h after squatting exercise. Moreover, RMR, physiological, metabolic and perceptual responses during sub-maximal running and EPOC were increased in the two days after squatting exercise (P<0.05). It is suggested that the elevated RMR was a consequence of a raised energy requirement for the degradation and resynthesis of damaged muscle fibres. The increased oxygen demand during sub-maximal running after muscle damage was responsible for the increase in EPOC. Individuals engaging in unaccustomed resistance exercise that results in muscle damage should be mindful of the increases in resting energy expenditure and increased metabolic demand to exercise in the days that follow.

Pediatric endurance and limb strengthening for children with cerebral palsy (PEDALS) – a randomized controlled trial protocol for a stationary cycling intervention

PubMed Central

Fowler, Eileen G; Knutson, Loretta M; DeMuth, Sharon K; Sugi, Mia; Siebert, Kara; Simms, Victoria; Azen, Stanley P; Winstein, Carolee J

2007-01-01

Background In the past, effortful exercises were considered inappropriate for children with spastic cerebral palsy (CP) due to concern that they would escalate abnormalities including spasticity and abnormal movement patterns. Current scientific evidence indicates that these concerns were unfounded and that therapeutic interventions focused on muscle strengthening can lead to improved functional ability. However, few studies have examined the potential benefits of cardiorespiratory fitness exercises in this patient population. Methods/design The rationale and design of a randomized controlled trial examining the effects of a stationary cycling intervention for children with CP are outlined here. Sixty children with spastic diplegic CP between the ages of 7 and 18 years and Gross Motor Function Classification System (GMFCS) levels of I, II, or III will be recruited for this study. Participants will be randomly assigned to either an intervention (cycling) or a control (no cycling) group. The cycling intervention will be divided into strengthening and cardiorespiratory endurance exercise phases. During the strengthening phase, the resistance to lower extremity cycling will be progressively increased using a uniquely designed limb-loaded mechanism. The cardiorespiratory endurance phase will focus on increasing the intensity and duration of cycling. Children will be encouraged to exercise within a target heart rate (HR) range (70 – 80% maximum HR). Thirty sessions will take place over a 10–12 week period. All children will be evaluated before (baseline) and after (follow-up) the intervention period. Primary outcome measures are: knee joint extensor and flexor moments, or torque; the Gross Motor Function Measure (GMFM); the 600 Yard Walk-Run test and the Thirty-Second Walk test (30 sec WT). Discussion This paper presents the rationale, design and protocol for Pediatric Endurance and Limb Strengthening (PEDALS); a Phase I randomized controlled trial evaluating the efficacy of a stationary cycling intervention for children with spastic diplegic cerebral palsy. PMID:17374171

Knee Kinetics during Squats of Varying Loads and Depths in Recreationally Trained Females.

PubMed

Flores, Victoria; Becker, James; Burkhardt, Eric; Cotter, Joshua

2018-03-06

The back squat exercise is typically practiced with varying squat depths and barbell loads. However, depth has been inconsistently defined, resulting in unclear safety precautions when squatting with loads. Additionally, females exhibit anatomical and kinematic differences to males which may predispose them to knee joint injuries. The purpose of this study was to characterize peak knee extensor moments (pKEMs) at three commonly practiced squat depths of above parallel, parallel, and full depth, and with three loads of 0% (unloaded), 50%, and 85% depth-specific one repetition maximum (1RM) in recreationally active females. Nineteen females (age, 25.1 ± 5.8 years; body mass, 62.5 ± 10.2 kg; height, 1.6 ± 0.10 m; mean ± SD) performed squats of randomized depth and load. Inverse dynamics were used to obtain pKEMs from three-dimensional knee kinematics. Depth and load had significant interaction effects on pKEMs (p = 0.014). Significantly greater pKEMs were observed at full depth compared to parallel depth with 50% 1RM load (p = 0.001, d = 0.615), and 85% 1RM load (p = 0.010, d = 0.714). Greater pKEMs were also observed at full depth compared to above parallel depth with 50% 1RM load (p = 0.003, d = 0.504). Results indicate effect of load on female pKEMs do not follow a progressively increasing pattern with either increasing depth or load. Therefore, when high knee loading is a concern, individuals are must carefully consider both the depth of squat being performed and the relative load they are using.

Knee Extensor and Flexor Torque Development with Concentric and Eccentric Isokinetic Training

ERIC Educational Resources Information Center

Miller, Larry E.; Pierson, Lee M.; Nickols-Richardson, Sharon M.; Wootten, David F.; Selmon, Serah E.; Ramp, Warren K.; Herbert, William G.

2006-01-01

This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training…

The influence of continuous versus interval walking exercise on knee joint loading and pain in patients with knee osteoarthritis.

PubMed

Farrokhi, Shawn; Jayabalan, Prakash; Gustafson, Jonathan A; Klatt, Brian A; Sowa, Gwendolyn A; Piva, Sara R

2017-07-01

To evaluate whether knee contact force and knee pain are different between continuous and interval walking exercise in patients with knee osteoarthritis (OA). Twenty seven patients with unilateral symptomatic knee OA completed two separate walking exercise sessions on a treadmill at 1.3m/s on two different days: 1) a continuous 45min walking exercise session, and 2) three 15min bouts of walking exercise separated by 1h rest periods for a total of 45min of exercise in an interval format. Estimated knee contact forces using the OpenSim software and knee pain were evaluated at baseline (1st minute of walking) and after every 15min between the continuous and interval walking conditions. A significant increase from baseline was observed in peak knee contact force during the weight-acceptance phase of gait after 30 and 45min of walking, irrespective of the walking exercise condition. Additionally, whereas continuous walking resulted in an increase in knee pain, interval walking did not lead to increased knee pain. Walking exercise durations of 30min or greater may lead to undesirable knee joint loading in patients with knee OA, while performing the same volume of exercise in multiple bouts as opposed to one continuous bout may be beneficial for limiting knee pain. Copyright © 2017. Published by Elsevier B.V.

Influence of obstructive sleep apnea syndrome in the fluctuation of the submaximal isometric torque of knee extensors in patients with early-grade osteoarthritis

PubMed Central

Silva, Andressa; Mello, Marco T.; Serrão, Paula R.; Luz, Roberta P.; Bittencourt, Lia R.; Mattiello, Stela M.

2015-01-01

OBJECTIVE: The aim of this study was to investigate whether obstructive sleep apnea (OSA) alters the fluctuation of submaximal isometric torque of the knee extensors in patients with early-grade osteoarthritis (OA). METHOD: The study included 60 male volunteers, aged 40 to 70 years, divided into four groups: Group 1 (G1) - Control (n=15): without OA and without OSA; Group 2 (G2) (n=15): with OA and without OSA; Group 3 (G3) (n=15): without OA and with OSA; and Group 4 (G4) (n=15) with OA and with OSA. Five patients underwent maximal isometric contractions of 10 seconds duration each, with the knee at 60° of flexion to determine peak torque at 60°. To evaluate the fluctuation of torque, 5 submaximal isometric contractions (50% of maximum peak torque) of 10 seconds each, which were calculated from the standard deviation of torque and coefficient of variation, were performed. RESULTS: Significant differences were observed between groups for maximum peak torque, while G4 showed a lower value compared with G1 (p=0.005). Additionally, for the average torque exerted, G4 showed a lower value compared to the G1 (p=0.036). However, no differences were found between the groups for the standard deviation (p=0.844) and the coefficient of variation (p=0.143). CONCLUSION: The authors concluded that OSA did not change the parameters of the fluctuation of isometric submaximal torque of knee extensors in patients with early-grade OA. PMID:26443974

The Myosuit: Bi-articular Anti-gravity Exosuit That Reduces Hip Extensor Activity in Sitting Transfers.

PubMed

Schmidt, Kai; Duarte, Jaime E; Grimmer, Martin; Sancho-Puchades, Alejandro; Wei, Haiqi; Easthope, Chris S; Riener, Robert

2017-01-01

Muscle weakness-which can result from neurological injuries, genetic disorders, or typical aging-can affect a person's mobility and quality of life. For many people with muscle weakness, assistive devices provide the means to regain mobility and independence. These devices range from well-established technology, such as wheelchairs, to newer technologies, such as exoskeletons and exosuits. For assistive devices to be used in everyday life, they must provide assistance across activities of daily living (ADLs) in an unobtrusive manner. This article introduces the Myosuit, a soft, wearable device designed to provide continuous assistance at the hip and knee joint when working with and against gravity in ADLs. This robotic device combines active and passive elements with a closed-loop force controller designed to behave like an external muscle (exomuscle) and deliver gravity compensation to the user. At 4.1 kg (4.6 kg with batteries), the Myosuit is one of the lightest untethered devices capable of delivering gravity support to the user's knee and hip joints. This article presents the design and control principles of the Myosuit. It describes the textile interface, tendon actuators, and a bi-articular, synergy-based approach for continuous assistance. The assistive controller, based on bi-articular force assistance, was tested with a single subject who performed sitting transfers, one of the most gravity-intensive ADLs. The results show that the control concept can successfully identify changes in the posture and assist hip and knee extension with up to 26% of the natural knee moment and up to 35% of the knee power. We conclude that the Myosuit's novel approach to assistance using a bi-articular architecture, in combination with the posture-based force controller, can effectively assist its users in gravity-intensive ADLs, such as sitting transfers.

The Myosuit: Bi-articular Anti-gravity Exosuit That Reduces Hip Extensor Activity in Sitting Transfers

PubMed Central

Schmidt, Kai; Duarte, Jaime E.; Grimmer, Martin; Sancho-Puchades, Alejandro; Wei, Haiqi; Easthope, Chris S.; Riener, Robert

2017-01-01

Muscle weakness—which can result from neurological injuries, genetic disorders, or typical aging—can affect a person's mobility and quality of life. For many people with muscle weakness, assistive devices provide the means to regain mobility and independence. These devices range from well-established technology, such as wheelchairs, to newer technologies, such as exoskeletons and exosuits. For assistive devices to be used in everyday life, they must provide assistance across activities of daily living (ADLs) in an unobtrusive manner. This article introduces the Myosuit, a soft, wearable device designed to provide continuous assistance at the hip and knee joint when working with and against gravity in ADLs. This robotic device combines active and passive elements with a closed-loop force controller designed to behave like an external muscle (exomuscle) and deliver gravity compensation to the user. At 4.1 kg (4.6 kg with batteries), the Myosuit is one of the lightest untethered devices capable of delivering gravity support to the user's knee and hip joints. This article presents the design and control principles of the Myosuit. It describes the textile interface, tendon actuators, and a bi-articular, synergy-based approach for continuous assistance. The assistive controller, based on bi-articular force assistance, was tested with a single subject who performed sitting transfers, one of the most gravity-intensive ADLs. The results show that the control concept can successfully identify changes in the posture and assist hip and knee extension with up to 26% of the natural knee moment and up to 35% of the knee power. We conclude that the Myosuit's novel approach to assistance using a bi-articular architecture, in combination with the posture-based force controller, can effectively assist its users in gravity-intensive ADLs, such as sitting transfers. PMID:29163120

The Interaction of Trunk-Load and Trunk-Position Adaptations on Knee Anterior Shear and Hamstrings Muscle Forces During Landing

PubMed Central

Kulas, Anthony S.; Hortobágyi, Tibor; DeVita, Paul

2010-01-01

Abstract Context: Because anterior cruciate ligament (ACL) injuries can occur during deceleration maneuvers, biomechanics research has been focused on the lower extremity kinetic chain. Trunk mass and changes in trunk position affect lower extremity joint torques and work during gait and landing, but how the trunk affects knee joint and muscle forces is not well understood. Objective: To evaluate the effects of added trunk load and adaptations to trunk position on knee anterior shear and knee muscle forces in landing. Design: Crossover study. Setting: Controlled laboratory environment. Patients or Other Participants: Twenty-one participants (10 men: age  =  20.3 ± 1.15 years, height  =  1.82 ± 0.04 m, mass  =  78.2 ± 7.3 kg; 11 women: age  =  20.0 ± 1.10 years, height  =  1.72 ± 0.06 m, mass  =  62.3 ± 6.4 kg). Intervention(s): Participants performed 2 sets of 8 double-leg landings under 2 conditions: no load and trunk load (10% body mass). Participants were categorized into one of 2 groups based on the kinematic trunk adaptation to the load: trunk flexor or trunk extensor. Main Outcome Measure(s): We estimated peak and average knee anterior shear, quadriceps, hamstrings, and gastrocnemius forces with a biomechanical model. Results: We found condition-by-group interactions showing that adding a trunk load increased peak (17%) and average (35%) knee anterior shear forces in the trunk-extensor group but did not increase them in the trunk-flexor group (peak: F1,19  =  10.56, P  =  .004; average: F1,19  =  9.56, P  =  .006). We also found a main effect for condition for quadriceps and gastrocnemius forces. When trunk load was added, peak (6%; F1,19  =  5.52, P  =  .030) and average (8%; F1,19  =  8.83, P  =  .008) quadriceps forces increased and average (4%; F1,19  =  4.94, P  =  .039) gastrocnemius forces increased, regardless of group. We found a condition-by-group interaction for peak (F1,19  =  5.16, P  =  .035) and average (F1,19  =  12.35, P  =  .002) hamstrings forces. When trunk load was added, average hamstrings forces decreased by 16% in the trunk-extensor group but increased by 13% in the trunk-flexor group. Conclusions: Added trunk loads increased knee anterior shear and knee muscle forces, depending on trunk adaptation strategy. The trunk-extensor adaptation to the load resulted in a quadriceps-dominant strategy that increased knee anterior shear forces. Trunk-flexor adaptations may serve as a protective strategy against the added load. These findings should be interpreted with caution, as only the face validity of the biomechanical model was assessed. PMID:20064042

Effects of Two Football Stud Types on Knee and Ankle Kinetics of Single-Leg Land-Cut and 180° Cut Movements on Infilled Synthetic Turf.

PubMed

Bennett, Hunter J; Brock, Elizabeth; Brosnan, James T; Sorochan, John C; Zhang, Songning

2015-10-01

Higher ACL injury rates have been recorded in cleats with higher torsional resistance in American football, which warrants better understanding of shoe/stud-dependent joint kinetics. The purpose of this study was to determine differences in knee and ankle kinetics during single-leg land cuts and 180° cuts on synthetic infilled turf while wearing 3 types of shoes. Fourteen recreational football players performed single-leg land cuts and 180° cuts in nonstudded running shoes (RS) and in football shoes with natural (NTS) and synthetic turf studs (STS). Knee and ankle kinetic variables were analyzed with a 3 × 2 (shoe × movement) repeated-measures ANOVA (P < .05). A significant shoe-by-movement interaction was found in loading response peak knee adduction moments, with NTS producing smaller moments compared with both STS and RS only in 180° cuts. Reduced peak negative plantar flexor powers were also found in NTS compared with STS. The single-leg land cut produced greater loading response and push-off peak knee extensor moments, as well as peak negative and positive extensor and plantar flexor powers, but smaller loading peak knee adduction moments and push-off peak ankle eversion moments than 180° cuts. Overall, the STS and 180° cuts resulted in greater frontal plane knee loading and should be monitored for possible increased ACL injury risks.

The influences of sex and posture on joint energetics during drop landings.

PubMed

Norcross, M F; Shultz, S J; Weinhold, P S; Lewek, M D; Padua, D A; Blackburn, J T

2015-04-01

Previous observations suggest that females utilize a more erect initial landing posture than males with sex differences in landing posture possibly related to sex-specific energy absorption (EA) strategies. However, sex-specific EA strategies have only been observed when accompanied by sex differences in initial landing posture. This study (a) investigated the potential existence of sex-specific EA strategies; and (b) determined the influences of sex and initial landing posture on the biomechanical determinants of EA. The landing biomechanics of 80 subjects were recorded during drop landings in Preferred, Flexed, and Erect conditions. No sex differences in joint EA were identified after controlling for initial landing posture. Males and females exhibited greater ankle EA during Erect vs Flexed landings with this increase driven by 12% greater ankle velocity, but no change in ankle extensor moment. No differences in hip and knee EA were observed between conditions. However, to achieve similar knee EA, subjects used 7% greater mean knee extensor moment but 9% less knee angular velocity during Flexed landings. The results suggest that sex-specific EA strategies do not exist, and that the magnitude of knee joint EA can be maintained by modulating the relative contributions of joint moment and angular velocity to EA. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

RELATIONSHIP BETWEEN ISOMETRIC THIGH MUSCLE STRENGTH AND MINIMAL CLINICALLY IMPORTANT DIFFERENCES (MCIDS) IN KNEE FUNCTION IN OSTEOARTHRITIS – DATA FROM THE OSTEOARTHRITIS INITIATIVE

PubMed Central

Ruhdorfer, Anja; Wirth, Wolfgang; Eckstein, Felix

2014-01-01

Objective To determine the relationship between thigh muscle strength and clinically relevant differences in self-assessed lower limb function. Methods Isometric knee extensor and flexor strength of 4553 Osteoarthritis Initiative participants (2651 women/1902 men) was related to Western Ontario McMasters Universities (WOMAC) physical function scores by linear regression. Further, groups of Male and female participant strata with minimal clinically important differences (MCIDs) in WOMAC function scores (6/68) were compared across the full range of observed values, and to participants without functional deficits (WOMAC=0). The effect of WOMAC knee pain and body mass index on the above relationships was explored using stepwise regression. Results Per regression equations, a 3.7% reduction in extensor and a 4.0% reduction in flexor strength were associated with an MCID in WOMAC function in women, and a 3.6%/4.8% reduction in men. For strength divided by body weight, reductions were 5.2%/6.7% in women and 5.8%/6.7% in men. Comparing MCID strata across the full observed range of WOMAC function confirmed the above estimates and did not suggest non-linear relationships across the spectrum of observed values. WOMAC pain correlated strongly with WOMAC function, but extensor (and flexor) muscle strength contributed significant independent information. Conclusion Reductions of approximately 4% in isometric muscle strength and of 6% in strength/weight were related to a clinically relevant difference in WOMAC functional disability. Longitudinal studies will need to confirm these relationships within persons. Muscle extensor (and flexor) strength (per body weight) provided significant independent information in addition to pain in explaining variability in lower limb function. PMID:25303012

Cross-sectional association between muscle strength and self-reported physical function in 195 hip osteoarthritis patients.

PubMed

Hall, Michelle; Wrigley, Tim V; Kasza, Jessica; Dobson, Fiona; Pua, Yong Hao; Metcalf, Ben R; Bennell, Kim L

2017-02-01

This study aimed to evaluate associations between strength of selected hip and knee muscles and self-reported physical function, and their clinical relevance, in men and women with hip osteoarthritis (OA). Cross-sectional data from 195 participants with symptomatic hip OA were used. Peak isometric torque of hip extensors, flexors, and abductors, and knee extensors were measured, along with physical function using the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire. Separate linear regressions in men and women were used to determine the association between strength and physical function accounting for age, pain, and radiographic disease severity. Subsequently, magnitudes of strength associated with estimates of minimal clinically important improvement (MCII) in physical function were estimated according to severity of difficulty with physical function. For men, greater strength of the hip extensors, hip flexors and knee extensors were each associated with better physical function. For women, greater muscle strength of all tested muscles were each associated with better physical function. For men and women, increases in muscle strength between 17-32%, 133-223%, and 151-284% may be associated with estimates of MCII in physical function for those with mild, moderate, and severe physical dysfunction, respectively. Greater isometric strength of specific hip and thigh muscle groups may be associated with better self-reported physical function in men and women. In people with mild physical dysfunction, an estimate of MCII in physical function may be associated with attainable increases in strength. However, in patients with more severe dysfunction, greater and perhaps unattainable strength increases may be associated with an estimate of MCII in physical function. Longitudinal studies are required to validate these observations. Copyright © 2017 Elsevier Inc. All rights reserved.

Kaatsu training to enhance physical function of older adults with knee osteoarthritis: Design of a randomized controlled trial.

PubMed

Buford, Thomas W; Fillingim, Roger B; Manini, Todd M; Sibille, Kimberly T; Vincent, Kevin R; Wu, Samuel S

2015-07-01

As the U.S. population ages, efficacious interventions are needed to manage pain and maintain physical function among older adults with osteoarthritis (OA). Skeletal muscle weakness is a primary contributory factor to pain and functional decline among persons with OA, thus interventions are needed that improve muscle strength. High-load resistance exercise is the best-known method of improving muscle strength; however high-compressive loads commonly induce significant joint pain among persons with OA. Thus interventions with low-compressive loads are needed which improve muscle strength while limiting joint stress. This study is investigating the potential of an innovative training paradigm, known as Kaatsu, for this purpose. Kaatsu involves performing low-load exercise while externally-applied compression partially restricts blood flow to the active skeletal muscle. The objective of this randomized, single-masked pilot trial is to evaluate the efficacy and feasibility of chronic Kaatsu training for improving skeletal muscle strength and physical function among older adults. Participants aged ≥ 60 years with physical limitations and symptomatic knee OA will be randomly assigned to engage in a 3-month intervention of either (1) center-based, moderate-load resistance training, or (2) Kaatsu training matched for overall workload. Study dependent outcomes include the change in 1) knee extensor strength, 2) objective measures of physical function, and 3) subjective measures of physical function and pain. This study will provide novel information regarding the therapeutic potential of Kaatsu training while also informing about the long-term clinical viability of the paradigm by evaluating participant safety, discomfort, and willingness to continually engage in the intervention. Copyright © 2015 Elsevier Inc. All rights reserved.

Physical fitness and physical activity in fatigued and non-fatigued inflammatory bowel disease patients.

PubMed

Vogelaar, Lauran; van den Berg-Emons, Rita; Bussmann, Hans; Rozenberg, Robert; Timman, Reinier; van der Woude, Christien J

2015-01-01

To assess physical fitness and physical activity in inflammatory bowel disease (IBD) patients and whether fatigue is associated with impaired physical fitness and impaired physical activity. Ten patients with quiescent IBD and fatigue (fatigue group [FG]) based on the Checklist Individual Strength-Fatigue score of ≥35 were matched for age (±5 years) and sex with a non-fatigue group (NFG) with IBD. Physical fitness was measured with a cyclo-ergometric-based maximal exercise test, a submaximal 6-min walk test, and a dynamometer test to quantify the isokinetic muscle strength of the knee extensors and flexors. Level of physical activity was measured with an accelerometer-based activity monitor. The patients in both groups did not differ in regard to medication use, clinical characteristics, and body composition. However, medium-to-large effect sizes for impaired physical fitness (both cardiorespiratory fitness and muscle strength) and physical activity were seen between the patients in the FG and the NFG. Especially, intensity of physical activity was significantly lower in the FG patients compared with the NFG patients (effect size: 1.02; p = 0.037). Similar results were seen when outcomes of the FG and NFG were compared with reference values of the normal population. Fatigued IBD patients show an impaired physical fitness and physical activity compared with non-fatigued IBD patients. This gives directions for a physical component in fatigue in IBD patients. Therefore, these new insights into fatigue indicate that these patients might benefit from an exercise program to improve physical fitness and physical activity.

Effects of lymphatic drainage and local cryo exposition regeneration after high-intensive exercises

PubMed Central

Behringer, Michael; Jedlicka, Diana; McCourt, Molly; Ring, Matthias; Mester, Joachim

2016-01-01

Summary Background Recovery from exercise and competition is important in sports medicine, particularly when rest periods are short. The objective is to determine the efficacy of cryo exposition (CRY) and manual lymphatic drainage (MLD) to hasten short term recovery of muscle performance after eccentric contractions. Methods In a randomized controlled trial, 30 healthy sport students (21 males, 9 females; age: 25.7±2.8 years) performed 4×20 eccentric contractions of knee extensors, followed by 30 min MLD, CRY, or rest (RST) under controlled laboratory environment. Maximal voluntary contractions (MVC), electrically induced muscle fatigue (FI), and electrically induced tetani (EIT) at low (T2: 20 Hz) and high frequencies were tested. Results Force decline and recovery kinetics regarding MVC, FI, and EIT did not differ significantly (p<0.05) between groups. That is, 24 h after the intervention, MVC (MLD: 80.9±5.5%; CRY: 81.1±8.5%; RST: 83.5±7.3%), FI (MLD: 83.2±23.7%; CRY: 81.2±38.8%; RST: 93.2±22.9%), and EIT (T1: MLD: 53.0±29.5%; CRY: 39.0±32.9%; RST: 46.3±26.1%; T2: MLD: 84.2±27.2%; CRY: 64.2±24.2%; RST: 66.6±22.3%) were similarly depressed irrespective of applied treatments. Conclusion Neither CRY nor MLD hastened the recovery of muscle performance, when applied for 30 min. Identification number of the Primary Registry Network: DRKS00007608. PMID:27900297

Effect of aquatic physical therapy on pain perception, functional capacity and quality of life in older people with knee osteoarthritis: study protocol for a randomized controlled trial.

PubMed

Alcalde, Guilherme Eleutério; Fonseca, Ana Carolina; Bôscoa, Thais Fernanda; Gonçalves, Mirella Regina; Bernardo, Gabriele Candido; Pianna, Bruna; Carnavale, Bianca Ferdin; Gimenes, Camila; Barrile, Silvia Regina; Arca, Eduardo Aguilar

2017-07-11

Aquatic therapy promotes short-term benefits for patients with knee osteoarthritis (OA), and it may be the first therapeutic option for this pathological condition. The objective of this study was to investigate the effects of an aquatic therapy program on pain intensity, functional ability, and quality of life in older people with knee OA. This is a parallel, two-arm, open, randomized controlled clinical trial with older people with knee OA. Volunteers will be allocated to an aquatic intervention group (WG), subjected to the intervention, or to a control group, not be subjected to any kind of intervention. Data collection pre- and postintervention will be composed of the evaluation of the perception of pain by visual analogue scale with application of nociceptive stimuli in four anatomical points of the knee, functional fitness tests, and application of the World Health Organization Quality of Life Scale abbreviated version and Western Ontario and McMaster Universities Osteoarthritis Index. The program will last 12 weeks, consisting of aerobic and functional exercises in the form of circuit training. The objective of this clinical trial is to evaluate the effect of aquatic therapy in elderly patients with knee OA. The study is guided by practice-based scientific evidence for the use of aquatic rehabilitation exercises. It is expected that the WG volunteers will show reduced pain intensity, increased flexibility, and improved functional capacity and quality of life. It is believed that the desired results can be attributed to physical and physiological effects of immersion in warm water associated with the exercise protocol proposed. The data will be published after completion of the study. Brazilian Registry of Clinical Trials (ReBEC) registration number: RBR-78h48d . Registered on 19 August 2015.

Effects of graded exercise-induced dehydration and rehydration on circulatory markers of oxidative stress across the resting and exercising human leg.

PubMed

Laitano, Orlando; Kalsi, Kameljit Kaur; Pearson, James; Lotlikar, Makra; Reischak-Oliveira, Alvaro; González-Alonso, José

2012-05-01

Exercise in the heat enhances oxidative stress markers in the human circulation, but the contribution of active skeletal muscle and the influence of hydration status remain unknown. To address this question, we measured leg exchange of glutathione (GSH), glutathione disulfide (GSSG), superoxide dismutase activity (SOD) and isoprostanes in seven males at rest and during submaximal one-legged knee extensor exercise in the following four conditions: (1) control euhydration (0% reduction in body mass), (2) mild-dehydration (2%), (3) moderate-dehydration (3.5%), (4) rehydration (0%). In all resting and control exercise conditions, a net GSH uptake was observed across the leg. In contrast, a significant leg release of GSH into the circulation (-354 ± 221 μmol/min, P < 0.05) was observed during exercise with moderate-dehydration, which was still present following full rehydration (-206 ± 122 μmol/min, P < 0.05). During exercise, mild and moderate-dehydration decreased both femoral venous erythrocyte SOD activity (195 ± 6 vs. 180 ± 5 U/L, P < 0.05) and plasma isoprostanes (30 ± 1.1 vs. 25.9 ± 1.3 pg/L, P < 0.05), but during rehydration these were not different from control. In conclusion, these findings suggest that active skeletal muscles release GSH into the circulation under moderate dehydration and subsequent rehydration, possibly to enhance the antioxidant defense.

Chronic effect of light resistance exercise after ingestion of a high-protein snack on increase of skeletal muscle mass and strength in young adults.

PubMed

Kato, Yushi; Sawada, Atsushi; Numao, Shigeharu; Suzuki, Masashige

2011-01-01

We have previously reported on the possibility that light resistance exercise performed with a high plasma amino acid concentration resulting from the ingestion of a high-protein snack (HPS; 15 g protein, 18 g sugar) 3 h after a basal meal promotes the utilization of amino acids in peripheral tissues such as muscle in both rats and humans. In the present study, we further examined the effectiveness of a daily routine involving ingestion of HPS 3 h after a basal meal and subsequent light resistance exercise (dumbbell exercise) in increasing the mass and strength of human muscle. Ten young adult males were subject to the following 3 conditions for 5 wk each, with sufficient recovery period between each condition: (1) Snack-Exercise (SE), (2) Snack-Sedentary (SS), and (3) No snack-Exercise (NE). The SE group showed a significant increase in lean body mass and total cross-sectional area (CSA) of the right forearm muscles along with a significant decrease in body fat mass. The SS group showed no change in body composition. Furthermore, the SE group showed significant increase in grip strength and isometric knee extensor muscle strength, while the SS group showed no increase in muscle strength. The NE group showed significant increase in grip strength. In conclusion, daily routine ingestion of HPS 3 h after a basal meal and subsequent light resistance exercise is effective in increasing the mass and strength of human muscle.

Polypropylene mesh augmentation for complete quadriceps rupture after total knee arthroplasty.

PubMed

Nodzo, Scott R; Rachala, Sridhar R

2016-01-01

Polypropylene mesh has previously been shown to be an effective treatment for failed patellar tendon repairs after total knee arthroplasty (TKA), but there have been few reports of this synthetic mesh used in complete quadriceps rupture after TKA. We retrospectively reviewed seven consecutive cases in six patients with complete quadriceps tears after TKA who had their quadriceps tendon repaired with suture and polypropylene mesh augmentation. All but two patients had previously failed primary suture repair. Patient outcomes were evaluated using the Knee Society Score. Standardized anterior-posterior (AP), lateral and merchant radiographs were evaluated preoperatively and at final follow-up. Seven knees in six patients were evaluated with a mean follow-up of 34±10 (range 24 to 49months) months. There were only four clinical successes defined as an extensor lag less than 30°. Of the functioning knees at final follow-up (n=5) the overall extensor lag in this group did significantly improve from 50±13° to 20±15° (range 5 to 40°) (p=.01). Mean postoperative flexion at final follow-up was 115±8°. Mean Knee Society Score for function improved from 20±30 to 45±54 (p=.03) as did the mean Knee Society Score for pain (44±18 vs. 74±78, p=.02). Polypropylene mesh offered limited postoperative functional results when used as an augment to the multiply operated knee that sustains a complete quadriceps rupture after TKA, but did allow for significant improvement in postoperative pain outcomes. IV. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of Motor Control Exercise Vs Muscle Stretching Exercise on Reducing Compensatory Lumbopelvic Motions and Low Back Pain: A Randomized Trial.

PubMed

Park, Kyue-Nam; Kwon, Oh-Yun; Yi, Chung-Hwi; Cynn, Heon-Seock; Weon, Jong-Hyuck; Kim, Tae-Ho; Choi, Houng-Sik

2016-10-01

The purpose of this study was to investigate the effectiveness of a 6-week motor control exercise (MCE) vs stretching exercise (SE) on reducing compensatory pelvic motion during active prone knee flexion (APKF) and intensity of low back pain. Thirty-six people in the lumbar-rotation-extension subgroup were randomly assigned equally into 2 exercise groups (18 people in each an MCE or SE group). A 3-dimensional motion-analysis system was used to measure the range and onset time of pelvic motion and knee flexion during APKF. Surface electromyography was used to measure the muscle activity and onset time of the erector spinae and the hamstrings during APKF. The level of subjective low back pain was measured using a visual analog scale. The MCE group had more significant decreases in and delay of anterior pelvic tilt, pelvic rotation, and erector spinae muscle activity during APKF, as well as reduced intensity of low back pain compared with the SE group (P < .05). For rehabilitation in patients in the lumbar-rotation-extension subgroup, MCE was more effective than SE in reducing compensatory pelvic motion and muscle activity during APKF and minimizing low back pain. Copyright © 2016. Published by Elsevier Inc.

Alpha-actinin-3 (ACTN3) R577X polymorphism influences knee extensor peak power response to strength training in older men and women.

PubMed

Delmonico, Matthew J; Kostek, Matthew C; Doldo, Neil A; Hand, Brian D; Walsh, Sean; Conway, Joan M; Carignan, Craig R; Roth, Stephen M; Hurley, Ben F

2007-02-01

The alpha-actinin-3 (ACTN3) R577X polymorphism has been associated with muscle power performance in cross-sectional studies. We examined baseline knee extensor concentric peak power (PP) and PP change with approximately 10 weeks of unilateral knee extensor strength training (ST) using air-powered resistance machines in 71 older men (65 [standard deviation = 8] years) and 86 older women (64 [standard deviation = 9] years). At baseline in women, the XX genotype group had an absolute (same resistance) PP that was higher than the RR (p =.005) and RX genotype groups (p =.02). The women XX group also had a relative (70% of one-repetition maximum [1-RM]) PP that was higher than that in the RR (p =.002) and RX groups (p =.008). No differences in baseline absolute or relative PP were observed between ACTN3 genotype groups in men. In men, absolute PP change with ST in the RR (n = 16) group approached a significantly higher value than in the XX group (n = 9; p =.07). In women, relative PP change with ST in the RR group (n = 16) was higher than in the XX group (n = 17; p =.02). The results indicate that the ACTN3 R577X polymorphism influences the response of quadriceps muscle power to ST in older adults.

Comparison of isokinetic muscle strength and muscle power by types of warm-up.

PubMed

Sim, Young-Je; Byun, Yong-Hyun; Yoo, Jaehyun

2015-05-01

[Purpose] The purpose of this study was to clarify the influence of static stretching at warm-up on the isokinetic muscle torque (at 60°/sec) and muscle power (at 180°/sec) of the flexor muscle and extensor muscle of the knee joint. [Subjects and Methods] The subjects of this study were 10 healthy students with no medically specific findings. The warm-up group and warm-up with stretching group performed their respective warm-up prior to the isokinetic muscle torque evaluation of the knee joint. One-way ANOVA was performed by randomized block design for each variable. [Results] The results were as follows: First, the flexor peak torque and extensor peak torque of the knee joint tended to decrease at 60°/sec in the warm-up with stretching group compared with the control group and warm-up group, but without statistical significance. Second, extensor power at 180°/sec was also not statistically significant. However, it was found that flexor power increased significantly in the warm-up with stretching group at 180°/sec compared with the control group and warm-up group in which stretching was not performed. [Conclusion] Therefore, it is considered that in healthy adults, warm-up including two sets of stretching for 20 seconds per muscle group does not decrease muscle strength and muscle power.

Impaired muscle strength may contribute to fatigue in patients with aneurysmal subarachnoid hemorrhage.

PubMed

Harmsen, Wouter J; Ribbers, Gerard M; Zegers, Bart; Sneekes, Emiel M; Praet, Stephan F E; Heijenbrok-Kal, Majanka H; Khajeh, Ladbon; van Kooten, Fop; Neggers, Sebastiaan J C M M; van den Berg-Emons, Rita J

2017-03-01

Patients with aneurysmal subarachnoid hemorrhage (a-SAH) show long-term fatigue and face difficulties in resuming daily physical activities. Impaired muscle strength, especially of the lower extremity, impacts the performance of daily activities and may trigger the onset of fatigue complaints. The present study evaluated knee muscle strength and fatigue in patients with a-SAH. This study included 33 patients, 6 months after a-SAH, and 33 sex-matched and age-matched healthy controls. Isokinetic muscle strength of the knee extensors and flexors was measured at 60 and 180°/s. Maximal voluntary muscle strength was defined as peak torque and measured in Newton-meter. Fatigue was examined using the Fatigue Severity Scale. In patients with a-SAH, the maximal knee extension was 22% (60°/s) and 25% (180°/s) lower and maximal knee flexion was 33% (60°/s) and 36% (180°/s) lower compared with that of matched controls (P≤0.001). The Fatigue Severity Scale score was related to maximal knee extension (60°/s: r=-0.426, P=0.015; 180°/s: r=-0.376, P=0.034) and flexion (60°/s: r=-0.482, P=0.005; 180°/s: r=-0.344, P=0.083). The knee muscle strength was 28-47% lower in fatigued (n=13) and 11-32% lower in nonfatigued (n=20) patients; deficits were larger in fatigued patients (P<0.05), particularly when the muscle strength (peak torque) was measured at 60°/s. The present results indicate that patients with a-SAH have considerably impaired knee muscle strength, which is related to more severe fatigue. The present findings are exploratory, but showed that knee muscle strength may play a role in the severity of fatigue complaints, or vice versa. Interventions targeting fatigue after a-SAH seem necessary and may consider strengthening exercise training in order to treat a debilitating condition.

Incorporation of photobiomodulation therapy into a therapeutic exercise program for knee osteoarthritis: A placebo-controlled, randomized, clinical trial.

PubMed

de Paula Gomes, Cid A F; Leal-Junior, Ernesto C P; Dibai-Filho, Almir V; de Oliveira, Adriano R; Bley, André S; Biasotto-Gonzalez, Daniela A; de Tarso Camillo de Carvalho, Paulo

2018-05-07

To investigate the clinical effects of incorporation of phototherapy in a therapeutic exercise program for individuals with knee osteoarthritis (OA) when compared to a group that received exercise alone and to a group that received exercise + placebo phototherapy. This is a randomized, blinded and placebo-controlled trial. Thus, sixty male and female individuals aged 40-80 years with knee pain in the previous 6 months participated of the study, with diagnosis of unilateral knee OA based on the criteria established by the American College of Rheumatology and radiographic confirmation and Grades 2 or 3 of the Kellgren-Lawrence Classification. The individuals were equally divided in the groups exercise alone, exercise + active phototherapy (nine-diode cluster device: one 905 nm super-pulsed diode laser, four 875 nm LED and four 640 nm LED; energy per quadrant: 7.85 J; total energy: 23.55 J per session), or exercise + placebo phototherapy. Treatments were performed twice a week for 5 consecutive weeks. Patients were evaluated before and after the sessions of treatment. The outcome measures were: Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Lower Extremity Functional Scale (LEFS), Numerical Rating Pain Scale (NRPS), pressure pain threshold (PPT) in two points of knee, muscle strength, and the Functional Reach Test (FRT). Exercise + active phototherapy was significantly more effective than exercise alone (mean difference [MD] = 2.75, 95% confidence interval [CI] = 3.17 to 2.32) and exercise + placebo phototherapy (MD = 2.38, 95% CI = 2.79 to 1.96) only with regard to the NRPS, considering minimal clinically important difference. No clinical significant results were found for function, the pressure pain threshold, muscle strength or balance. The combination of phototherapy and an exercise program is effective at reducing pain intensity among individuals with knee osteoarthritis than exercise alone or exercise + placebo phototherapy in a short-term protocol. Lasers Surg. Med. 9999: 1-10, 2018 © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

A Methodologic Approach for Normalizing Angular Work and Velocity During Isotonic and Isokinetic Eccentric Training

PubMed Central

Guilhem, Gaël; Cornu, Christophe; Guével, Arnaud

2012-01-01

Context: Resistance exercise training commonly is performed against a constant external load (isotonic) or at a constant velocity (isokinetic). Researchers comparing the effectiveness of isotonic and isokinetic resistance-training protocols need to equalize the mechanical stimulus (work and velocity) applied. Objective: To examine whether the standardization protocol could be adjusted and applied to an eccentric training program. Design: Controlled laboratory study. Setting: Controlled research laboratory. Patients or Other Participants: Twenty-one sport science male students (age = 20.6 ± 1.5 years, height = 178.0 ± 4.0 cm, mass = 74.5 ± 9.1 kg). Intervention(s): Participants performed 9 weeks of isotonic (n = 11) or isokinetic (n = 10) eccentric training of knee extensors that was designed so they would perform the same amount of angular work at the same mean angular velocity. Main Outcome Measure(s): Angular work and angular velocity. Results: The isotonic and isokinetic groups performed the same total amount of work (−185.2 ± 6.5 kJ and −184.4 ± 8.6 kJ, respectively) at the same angular velocity (21 ± 1°/s and 22°/s, respectively) with the same number of repetitions (8.0 and 8.0, respectively). Bland-Altman analysis showed that work (bias = 2.4%) and angular velocity (bias = 0.2%) were equalized over 9 weeks between the modes of training. Conclusions: The procedure developed allows angular work and velocity to be standardized over 9 weeks of isotonic and isokinetic eccentric training of the knee extensors. This method could be useful in future studies in which researchers compare neuromuscular adaptations induced by each type of training mode with respect to rehabilitating patients after musculoskeletal injury. PMID:22488276

The Trainability of Adolescent Soccer Players to Brief Periodized Complex Training.

PubMed

Chatzinikolaou, Athanasios; Michaloglou, Konstantinos; Avloniti, Alexandra; Leontsini, Diamanda; Deli, Chariklia K; Vlachopoulos, Dimitris; Gracia-Marco, Luis; Arsenis, Sotirios; Athanailidis, Ioannis; Draganidis, Dimitrios; Jamurtas, Athanasios Z; Williams, Craig A; Fatouros, Ioannis G

2018-05-01

To investigate the effect of a complex, short-term strength/power training protocol on performance and body composition of elite early adolescent soccer players. Twenty-two players (14-15 y) were randomly assigned to (1) an experimental group (N = 12; participated in a 5-wk training protocol with traditional multijoint power resistance exercises, Olympic-style lifts, plyometric drills, and speed work; 4 times per week) or (2) a control group (N = 10). Strength and power performance (jumping, speed, change of direction, repeated sprint ability, endurance, isokinetic strength of knee flexors and extensors, maximal strength in various lifts, and speed-endurance) were evaluated pretraining and posttraining. Cessation of training for 5 weeks in the control group induced a marked performance deterioration (∼5%-20%). Training not only prevented strength performance deterioration but also increased it (∼2%-30%). Endurance and repeated sprint ability declined to a smaller extent in experimental group compared with control group (15% vs 7.5%). Isometric strength and body composition remained unaltered in both groups. Results demonstrate that (1) young players exhibit a high level of trainability of their strength/power performance (but not endurance) in response to a short-term complex training protocol during early adolescence, (2) Olympic-style lifts are characterized by increased safety in this age group and appear to be highly effective, (3) lifts incorporating a hip thrust result in increased strength of both knee extensors and flexors, (4) cessation of training for only 5 weeks results in marked deterioration of strength/power and endurance performance, and (5) improvement of strength/power performance may be related to neural-based adaptation as body composition remained unaffected.

Effects of Barbell Deadlift Training on Submaximal Motor Unit Firing Rates for the Vastus Lateralis and Rectus Femoris

PubMed Central

Stock, Matt S.; Thompson, Brennan J.

2014-01-01

Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units. PMID:25531294

The effect of exercise therapy on knee adduction moment in individuals with knee osteoarthritis: A systematic review.

PubMed

Ferreira, Giovanni E; Robinson, Caroline Cabral; Wiebusch, Matheus; Viero, Carolina Cabral de Mello; da Rosa, Luis Henrique Telles; Silva, Marcelo Faria

2015-07-01

Exercise therapy is an evidence-based intervention for the conservative management of knee osteoarthritis. It is hypothesized that exercise therapy could reduce the knee adduction moment. A systematic review was performed in order to verify the effects of exercise therapy on the knee adduction moment in individuals with knee osteoarthritis in studies that also assessed pain and physical function. A comprehensive electronic search was performed on MEDLINE, Cochrane CENTRAL, EMBASE, Google scholar and OpenGrey. Inclusion criteria were randomized controlled trials with control or sham groups as comparator assessing pain, physical function, muscle strength and knee adduction moment during walking at self-selected speed in individuals with knee osteoarthritis that underwent a structured exercise therapy rehabilitation program. Two independent reviewers extracted the data and assessed risk of bias. For each study, knee adduction moment, pain and physical function outcomes were extracted. For each outcome, mean differences and 95% confidence intervals were calculated. Due to clinical heterogeneity among exercise therapy protocols, a descriptive analysis was chosen. Three studies, comprising 233 participants, were included. None of the studies showed significant differences between strengthening and control/sham groups in knee adduction moment. In regards to pain and physical function, the three studies demonstrated significant improvement in pain and two of them showed increased physical function following exercise therapy compared to controls. Muscle strength and torque significantly improved in all the three trials favoring the intervention group. Clinical benefits from exercise therapy were not associated with changes in the knee adduction moment. The lack of knee adduction moment reduction indicates that exercise therapy may not be protective in knee osteoarthritis from a joint loading point of view. Alterations in neuromuscular control, not captured by the knee adduction moment measurement, may contribute to alter dynamic joint loading following exercise therapy. To conclude, mechanisms other than the reduction in knee adduction moment might explain the clinical benefits of exercise therapy on knee osteoarthritis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stance controlled knee flexion improves stimulation driven walking after spinal cord injury

PubMed Central

2013-01-01

Background Functional neuromuscular stimulation (FNS) restores walking function after paralysis from spinal cord injury via electrical activation of muscles in a coordinated fashion. Combining FNS with a controllable orthosis to create a hybrid neuroprosthesis (HNP) has the potential to extend walking distance and time by mechanically locking the knee joint during stance to allow knee extensor muscle to rest with stimulation turned off. Recent efforts have focused on creating advanced HNPs which couple joint motion (e.g., hip and knee or knee and ankle) to improve joint coordination during swing phase while maintaining a stiff-leg during stance phase. Methods The goal of this study was to investigate the effects of incorporating stance controlled knee flexion during loading response and pre-swing phases on restored gait. Knee control in the HNP was achieved by a specially designed variable impedance knee mechanism (VIKM). One subject with a T7 level spinal cord injury was enrolled and served as his own control in examining two techniques to restore level over-ground walking: FNS-only (which retained a stiff knee during stance) and VIKM-HNP (which allowed controlled knee motion during stance). The stimulation pattern driving the walking motion remained the same for both techniques; the only difference was that knee extensor stimulation was constant during stance with FNS-only and modulated together with the VIKM to control knee motion during stance with VIKM-HNP. Results Stance phase knee angle was more natural during VIKM-HNP gait while knee hyperextension persisted during stiff-legged FNS-only walking. During loading response phase, vertical ground reaction force was less impulsive and instantaneous gait speed was increased with VIKM-HNP, suggesting that knee flexion assisted in weight transfer to the leading limb. Enhanced knee flexion during pre-swing phase also aided flexion during swing, especially when response to stimulation was compromised. Conclusions These results show the potential advantages of incorporating stance controlled knee flexion into a hybrid neuroprosthesis for walking. The addition of such control to FNS driven walking could also enable non-level walking tasks such as uneven terrain, slope navigation and stair descent where controlled knee flexion during weight bearing is critical. PMID:23826711

Reliability and validity of the Performance Recorder 1 for measuring isometric knee flexor and extensor strength.

PubMed

Neil, Sarah E; Myring, Alec; Peeters, Mon Jef; Pirie, Ian; Jacobs, Rachel; Hunt, Michael A; Garland, S Jayne; Campbell, Kristin L

2013-11-01

Muscular strength is a key parameter of rehabilitation programs and a strong predictor of functional capacity. Traditional methods to measure strength, such as manual muscle testing (MMT) and hand-held dynamometry (HHD), are limited by the strength and experience of the tester. The Performance Recorder 1 (PR1) is a strength assessment tool attached to resistance training equipment and may be a time- and cost-effective tool to measure strength in clinical practice that overcomes some limitations of MMT and HHD. However, reliability and validity of the PR1 have not been reported. Test-retest and inter-rater reliability was assessed using the PR1 in healthy adults (n  =  15) during isometric knee flexion and extension. Criterion-related validity was assessed through comparison of values obtained from the PR1 and Biodex® isokinetic dynamometer. Test-retest reliability was excellent for peak knee flexion (intra-class correlation coefficient [ICC] of 0.96, 95% CI: 0.85, 0.99) and knee extension (ICC  =  0.96, 95% CI: 0.87, 0.99). Inter-rater reliability was also excellent for peak knee flexion (ICC  =  0.95, 95% CI: 0.85, 0.99) and peak knee extension (ICC  =  0.97, 95% CI: 0.91, 0.99). Validity was moderate for peak knee flexion (ICC  =  0.75, 95% CI: 0.38, 0.92) but poor for peak knee extension (ICC  =  0.37, 95% CI: 0, 0.73). The PR1 provides a reliable measure of isometric knee flexor and extensor strength in healthy adults that could be used in the clinical setting, but absolute values may not be comparable to strength assessment by gold-standard measures.

THIGH MUSCLE CROSS-SECTIONAL AREAS AND STRENGTH IN KNEES WITH EARLY VS KNEES WITHOUT RADIOGRAPHIC KNEE OSTEOARTHRITIS: A BETWEEN-KNEE, WITHIN-PERSON COMPARISON

PubMed Central

Ruhdorfer, AS; Dannhauer, T; Wirth, W; Cotofana, S; Roemer, F; Nevitt, M; Eckstein, F

2014-01-01

Objective To compare cross-sectional and longitudinal side-differences in thigh muscle anatomical cross-sectional areas (ACSAs), muscle strength, and specific strength (strength/ACSA), between knees with early radiographic change vs. knees without radiographic knee osteoarthritis (RKOA), in the same person. Design 55 (of 4796) Osteoarthritis Initiative participants fulfilled the inclusion criteria of early RKOA in one limb (definite tibiofemoral osteophytes; no radiographic joint space narrowing [JSN]) vs. no RKOA (no osteophyte; no JSN) in the contralateral limb. ACSAs of the thigh muscles and quadriceps heads were determined using axial MRIs at 33%/30% femoral length (distal to proximal). Isometric extensor and flexor muscle strength were measured (Good Strength Chair). Baseline quadriceps ACSA and extensor (specific) strength represented the primary analytic focus, and two-year changes of quadriceps ACSAs the secondary focus. Results No statistically significant side-differences in quadriceps (or other thigh muscle) ACSAs, muscle strength, or specific strength were observed between early RKOA vs. contralateral limbs without RKOA (p≥0.44), neither in men nor in women. The two-year reduction in quadriceps ACSA in limbs with early RKOA was −0.9±6% (mean ± standard deviation) vs. −0.5±6% in limbs without RKOA (statistical difference p=0.85). Conclusion Our results do not provide evidence that early unilateral radiographic changes, i.e. presence of osteophytes, are associated with cross-sectional or longitudinal differences in quadriceps muscle status compared with contralateral knees without RKOA. At the stage of early unilateral RKOA there thus appears to be no clinical need for countervailing a potential dys-balance in quadriceps ACSAs and strength between both knees. PMID:25278072

Annual Progress Report, Fiscal Year 1981.

DTIC Science & Technology

1981-09-30

Ticlopidine Hydrochloride - A Clinical Trial in Patients with Transient Cerebral or Monocular Ischemic Attacks ............... 138 Work Unit No. 81/57...Hand Injuries .................................... 180 Work Unit No. 80/06 (FY8O,C) Evaluation of Antagonistic Knee Flexors and Extensors During Prone...Preventable Training Injury : Accepted for publication in Military Medicine(C). Smith WR, Lee SH, Vichick DA: Evaluation of Antagonistic Knee Flexors and

Effects of WiiActive exercises on fear of falling and functional outcomes in community-dwelling older adults: a randomised control trial.

PubMed

Kwok, Boon Chong; Pua, Yong Hao

2016-09-01

the study compares the effects of a Nintendo Wii exercise programme and a standard Gym-based exercise intervention on fear of falling, knee strength, physical function and falls rate in older adults. eighty community-dwelling adults aged 60 years and above with short physical performance battery score of 5-9 points and modified falls efficacy scale (MFES) score of ≤9 points participated in the parallel-group randomised trial. Each intervention arm involved an hour of intervention per week, totalling 12 sessions over 12 weeks. Besides 1-year fall incidence, the participants were evaluated on MFES, knee extensor strength (KES), timed-up-and-go test, gait speed, 6-minute walk test and narrow corridor walk test at weeks 13 and 24. at week 13, between interventions, the effect of MFES changes did not reach statistical significance (difference = -0.07 point, 95% CI -0.56 to 0.42, P = 0.78); at week 24, the Wii group showed statistically significant effects over the Gym group (difference = 0.8 point, 95% CI 0.27 to 1.29, P < 0.01). For KES, the two groups did not differ statistically at week 13 (difference = -2.0%, 95% CI -5.6 to -1.7, P = 0.29); at week 24, the Gym group had greater strength gains than the Wii group (difference = -5.1%, 95% CI -8.7 to -1.5, P < 0.01). No between-group differences were observed for other outcome measures. on completion of a 12-week Nintendo Wii exercise programme, there was no significant benefit seen on fear of falling when compared to a standard Gym-based exercise intervention; however, post-intervention there was an apparent reduction in fear of falling in the group allocated to Wii training, despite knee strength apparently improving more in those allocated to the Gym. It is possible that long-term gains after using the Wii might be due to a carry-over effect. Australian New Zealand Clinical Trials Registry, ACTRN12610000576022. © The Author 2016. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Spinal mobility and trunk muscle strength in elite hockey players.

PubMed

Lindgren, S; Twomey, L

1988-01-01

Elite hockey players of both sexes from the Australian Institute of Sport were assessed for lumbar spine mobility, trunk flexion and back extensor muscle strength, hamstring flexibility and postural characteristics over a two year period. All the athletes were more mobile in rotation than the 'normal' West Australian population, and demonstrated flexible hamstrings and powerful back extensor muscles; trunk flexion was less strong initially, but improved after intervention in the form of a specific exercise programme, over the measurement period. A questionnaire disclosed that low back pain is a common complaint of hockey players, but rarely required intensive physical and medical treatment. The term 'hockey player's back' has been coined in recognition of the long flat thoracolumbar spine frequently noted in these subjects. Copyright © 1988 Australian Physiotherapy Association. Published by . All rights reserved.

Physical Examination of the Knee: Meniscus, Cartilage, and Patellofemoral Conditions.

PubMed

Bronstein, Robert D; Schaffer, Joseph C

2017-05-01

The knee is one of the most commonly injured joints in the body. Its superficial anatomy enables diagnosis of the injury through a thorough history and physical examination. Examination techniques for the knee described decades ago are still useful, as are more recently developed tests. Proper use of these techniques requires understanding of the anatomy and biomechanical principles of the knee as well as the pathophysiology of the injuries, including tears to the menisci and extensor mechanism, patellofemoral conditions, and osteochondritis dissecans. Nevertheless, the clinical validity and accuracy of the diagnostic tests vary. Advanced imaging studies may be useful adjuncts.

Volume and fat infiltration of spino-pelvic musculature in adults with spinal deformity

PubMed Central

Moal, Bertrand; Bronsard, Nicolas; Raya, José G; Vital, Jean Marc; Schwab, Frank; Skalli, Wafa; Lafage, Virginie

2015-01-01

AIM: To investigate fat infiltration and volume of spino-pelvic muscles in adults spinal deformity (ASD) with magnetic resonance imaging (MRI) and 3D reconstructions. METHODS: Nineteen female ASD patients (mean age 60 ± 13) were included prospectively and consecutively and had T1-weighted Turbo Spin Echo sequence MRIs with Dixon method from the proximal tibia up to T12 vertebra. The Dixon method permitted to evaluate the proportion of fat inside each muscle (fat-water ratio). In order to investigate the accuracy of the Dixon method for estimating fat vs water, the same MRI acquisition was performed on phantoms of four vials composed of different proportion of fat vs water. With Muscl’X software, 3D reconstructions of 17 muscles or group of muscles were obtained identifying the muscle’s contour on a limited number of axial images [Deformation of parametric specific objects (DPSO) Method]. Musclar volume (Vmuscle), infiltrated fat volume (Vfat) and percentage of fat infiltration [Pfat, calculated as follow: Pfat = 100 × (Vfat/Vmuscle)] were characterized by extensor or flexor function respectively for the spine, hip and knee and theirs relationship with demographic data were investigated. RESULTS: Phantom acquisition demonstrated a non linear relation between Dixon fat-water ratio and the real fat-water ratio. In order to correct the Dixon fat-water ratio, the non linear relation was approximated with a polynomial function of degree three using the phantom acquisition. On average, Pfat was 13.3% ± 5.3%. Muscles from the spinal extensor group had a Pfat significantly greater than the other muscles groups, and the largest variability (Pfat = 31.9% ± 13.8%, P < 0.001). Muscles from the hip extensor group ranked 2nd in terms of Pfat (14% ± 8%), and were significantly greater than those of the knee extensor (P = 0.030). Muscles from the knee extensor group demonstrated the least Pfat (12% ± 8%). They were also the only group with a significant correlation between Vmuscle and Pfat (r = -0.741, P < 0.001), however this correlation was lacking in the other groups. No correlation was found between the Vmuscle total and age or body mass index. Except for the spine flexors, Pfat was correlated with age. Vmuscle and Vfat distributions demonstrated that muscular degeneration impacted the spinal extensors most. CONCLUSION: Mechanisms of fat infiltration are not similar among the muscle groups. Degeneration impacted the spinal and hip extensors most, key muscles of the sagittal alignment. PMID:26495250

Combination of body mass-based resistance training and high-intensity walking can improve both muscle size and V˙O2 peak in untrained older women.

PubMed

Ozaki, Hayao; Kitada, Tomoharu; Nakagata, Takashi; Naito, Hisashi

2017-05-01

Here, we aimed to compare the effect of a combination of body mass-based resistance exercise and moderate-intensity (55% peak oxygen uptake [ V˙O 2 peak]) walking or high-intensity (75% V˙O 2 peak) walking on muscle size and V˙O 2 peak in untrained older women. A total of 12 untrained older women (mean age 60 ± 2 years) were randomly assigned to either a moderate-intensity aerobic training group (n = 6) or high-intensity aerobic training group (n = 6). Both groups carried out body-mass based (lower body) resistance exercises (2 sets of 10 repetitions) on 3 days/week for 8 weeks. Between these exercises, the participants in the moderate-intensity aerobic training group walked at a previously determined speed equivalent to 55% V˙O 2 peak, whereas those in the high-intensity aerobic training group walked at a speed equivalent to 75% V˙O 2 peak. Muscle thickness of the anterior aspect of the thigh and maximal isokinetic knee extension strength significantly increased in both groups (P < 0.01); these relative changes were negatively correlated with the absolute muscle thickness of the anterior aspect of the thigh value and the relative value of maximal knee strength to body mass at pre-intervention, respectively. A significant group × time interaction was noted for V˙O 2 peak (P < 0.05), which increased only in the high-intensity aerobic training group. Body mass-based resistance training significantly induced muscle hypertrophy in untrained older women. In particular, lower muscle thickness before intervention was associated with greater training-induced growth. Furthermore, V˙O 2 peak can be increased by combined circuit training involving low-load resistance exercise and walking, particularly when a relatively high intensity of walking is maintained. Geriatr Gerontol Int 2017; 17: 779-784. © 2016 Japan Geriatrics Society.

Effects of a prior high-intensity knee-extension exercise on muscle recruitment and energy cost: a combined local and global investigation in humans.

PubMed

Layec, Gwenael; Bringard, Aurélien; Le Fur, Yann; Vilmen, Christophe; Micallef, Jean-Paul; Perrey, Stéphane; Cozzone, Patrick J; Bendahan, David

2009-06-01

The effects of a priming exercise bout on both muscle energy production and the pattern of muscle fibre recruitment during a subsequent exercise bout are poorly understood. The purpose of the present study was to determine whether a prior exercise bout which is known to increase O(2) supply and to induce a residual acidosis could alter energy cost and muscle fibre recruitment during a subsequent heavy-intensity knee-extension exercise. Fifteen healthy subjects performed two 6 min bouts of heavy exercise separated by a 6 min resting period. Rates of oxidative and anaerobic ATP production, determined with (31)P-magnetic resonance spectroscopy, and breath-by-breath measurements of pulmonary oxygen uptake were obtained simultaneously. Changes in muscle oxygenation and muscle fibre recruitment occurring within the quadriceps were measured using near-infrared spectroscopy and surface electromyography. The priming heavy-intensity exercise increased motor unit recruitment (P < 0.05) in the early part of the subsequent exercise bout but did not alter muscle energy cost. We also observed a reduced deoxygenation time delay, whereas the deoxygenation amplitude was increased (P < 0.01). These changes were associated with an increased oxidative ATP cost after approximately 50 s (P < 0.05) and a slight reduction in the overall anaerobic rate of ATP production (0.11 +/- 0.04 mM min(-1) W(-1) for bout 1 and 0.06 +/- 0.11 mM min(-1) W(-1) for bout 2; P < 0.05). We showed that a priming bout of heavy exercise led to an increased recruitment of motor units in the early part of the second bout of heavy exercise. Considering the increased oxidative cost and the unaltered energy cost, one could suggest that our results illustrate a reduced metabolic strain per fibre.

Is the deleterious effect of cryotherapy on proprioception mitigated by exercise?

PubMed

Ribeiro, F; Moreira, S; Neto, J; Oliveira, J

2013-05-01

This study aimed to examine the acute effects of cryotherapy on knee position sense and to determine the time period necessary to normalize joint position sense when exercising after cryotherapy. 12 subjects visited the laboratory twice, once for cryotherapy followed by 30 min of exercise on a cycloergometer and once for cryotherapy followed by 30 min of rest. Sessions were randomly determined and separated by 48 h. Cryotherapy was applied in the form of ice bag, filled with 1 kg of crushed ice, for 20 min. Knee position sense was measured at baseline, after cryotherapy and every 5 min after cryotherapy removal until a total of 30 min. The main effect of cryotherapy was significant showing an increase in absolute (F7,154=43.76, p<0.001) and relative (F7,154=7.97, p<0.001) errors after cryotherapy. The intervention after cryotherapy (rest vs. exercise) revealed a significant main effect only for absolute error (F7,154=4.05, p<0.001), i.e., when subjects exercised after cryotherapy, the proprioceptive acuity reached the baseline values faster (10 min vs. 15 min). Our results indicated that the deleterious effect of cryotherapy on proprioception is mitigated by low intensity exercise, being the time necessary to normalize knee position sense reduced from 15 to 10 min. © Georg Thieme Verlag KG Stuttgart · New York.

High-intensity sprint fatigue does not alter constant-submaximal velocity running mechanics and spring-mass behavior.

PubMed

Morin, Jean-Benoit; Tomazin, Katja; Samozino, Pierre; Edouard, Pascal; Millet, Guillaume Y

2012-04-01

We investigated the changes in constant velocity spring-mass behavior after high intensity sprint fatigue in order to better interpret the results recently reported after ultra-long distance (ULD) exercises. Our hypothesis was that after repeated sprints (RS), subjects may likely experience losses of force such as after ULD, but the necessity to modify their running pattern to attenuate the overall impact at each step (such as after ULD) may not be present. Eleven male subjects performed four sets of five 6-s sprints with 24-s recovery between sprints and 3 min between sets, on a sprint treadmill and on a bicycle ergometer. For each session, their running mechanics and spring-mass characteristics were measured at 10 and 20 km h(-1) on an instrumented treadmill before and after RS. Two-way (period and velocity) ANOVAs showed that high-intensity fatigue did not induce any change in the constant velocity running pattern at low or high velocity, after both running and cycling RS, despite significant decreases (P < 0.001) in maximal power (-27.1 ± 8.2% after running RS and -15.4 ± 11.5 % after cycling RS) and knee extensors maximal voluntary force (-18.8 ± 6.7 % after running RS and -15.0 ± 7.6 % after cycling RS). These results bring indirect support to the hypothesis put forward in recent ULD studies that the changes in running mechanics observed after ULD are likely not related to the decrease in strength capabilities, but rather to the necessity for subjects to adopt a protective running pattern.

The relation between knee muscle strength and performance tests in orienteering athletes.

PubMed

Çinar-Medeni, Özge; Colakoglu, Fatma F; Yüce, Koray; Ipekoğlu, Gökhan; Baltaci, Gul

2016-11-01

The aim of this study was to analyze the effect of knee muscle strength on performance tests in orienteers. Thirty-seven orienteers were voluntarily included in this study. Isokinetic knee flexor and extensor muscles' strength was assessed at 120°/s velocity for both "dominant leg" (DL) and "non-dominant leg" (NDL). "Single-legged hop test" (SLHT), "flamingo balance test" (FBT), "star excursion balance test" (SEBT), vertical jump-and-reach test (for anaerobic power), T-drill test and 20-meter shuttle run test (for aerobic power) were carried out. Correlation and regression analyses were performed on the data. VO2max levels showed moderate correlations with DL's "flexor peak torque" (FPT) and NDL's "extensor peak torque" (EPT) and FPT values respectively (r=0.49, r=0.38, r=0.58). FPT of NDL was a predictor of VO2max level (R2=0.33). Anaerobic power has a relationship with EPT of NDL (r=0.43) and T-drill test with EPT and FPT values of both DL and NDL respectively (r=-0.35, r=-0.63, r=-0.53, r=-0.58). EPT of NDL was a predictor for anaerobic power (R2=0.19) and FPT of DL for agility (R2=0.40). Nonparametric linear regression results showed that EPT is a predictor in DL (median slope=-0.71, P=0.01), and FPT in NDL (median slope=-0.90, P=0.006) for FBT. FPT was a predictor of SEBT scores for both legs (0.13

Barbell deadlift training increases the rate of torque development and vertical jump performance in novices.

PubMed

Thompson, Brennan J; Stock, Matt S; Shields, JoCarol E; Luera, Micheal J; Munayer, Ibrahim K; Mota, Jacob A; Carrillo, Elias C; Olinghouse, Kendra D

2015-01-01

The primary purpose of this study was to examine the effects of 10 weeks of barbell deadlift training on rapid torque characteristics of the knee extensors and flexors. A secondary aim was to analyze the relationships between training-induced changes in rapid torque and vertical jump performance. Fifty-four subjects (age, mean ± SD = 23 ± 3 years) were randomly assigned to a control (n = 20) or training group (n = 34). Subjects in the training group performed supervised deadlift training twice per week for 10 weeks. All subjects performed isometric strength testing of the knee extensors and flexors and vertical jumps before and after the intervention. Torque-time curves were used to calculate rate of torque development (RTD) values at peak and at 50 and 200 milliseconds from torque onset. Barbell deadlift training induced significant pre- to post-increases of 18.8-49.0% for all rapid torque variables (p < 0.01). Vertical jump height increased from 46.0 ± 11.3 to 49.4 ± 11.3 cm (7.4%; p < 0.01), and these changes were positively correlated with improvements in RTD for the knee flexors (r = 0.30-0.37, p < 0.01-0.03). These findings showed that a 10-week barbell deadlift training program was effective at enhancing rapid torque capacities in both the knee extensors and flexors. Changes in rapid torque were associated with improvements in vertical jump height, suggesting a transfer of adaptations from deadlift training to an explosive, performance-based task. Professionals may use these findings when attempting to design effective, time-efficient resistance training programs to improve explosive strength capacities in novices.

Running and Osteoarthritis: Does Recreational or Competitive Running Increase the Risk?

PubMed

2017-06-01

Exercise, like running, is good for overall health and, specifically, our hearts, lungs, muscles, bones, and brains. However, some people are concerned about the impact of running on longterm joint health. Does running lead to higher rates of arthritis in knees and hips? While many researchers find that running protects bone health, others are concerned that this exercise poses a high risk for age-related changes to hips and knees. A study published in the June 2017 issue of JOSPT suggests that the difference in these outcomes depends on the frequency and intensity of running. J Orthop Sports Phys Ther 2017;47(6):391. doi:10.2519/jospt.2017.0505.

Effects of a progressive resistance exercise program with high-speed component on the physical function of older women with sarcopenic obesity: a randomized controlled trial

PubMed Central

Vasconcelos, Karina S. S.; Dias, João M. D.; Araújo, Marília C.; Pinheiro, Ana C.; Moreira, Bruno S.; Dias, Rosângela C.

2016-01-01

ABSTRACT Background Sarcopenic obesity is associated with disability in older people, especially in women. Resistance exercises are recommended for this population, but their efficacy is not clear. Objective To evaluate the effects of a progressive resistance exercise program with high-speed component on the physical function of older women with sarcopenic obesity. Method Twenty-eight women 65 to 80 years old, with a body mass index ≥30kg/m2 and handgrip strength ≤21kg were randomly allocated to two groups. The experimental group underwent a 10-week resistance exercise program designed to improve strength, power, and endurance of lower-limb muscles, with open chain and closed chain exercises. The control group had their health status monitored through telephone calls. The primary outcomes were lower limb muscle performance measured by knee extensor strength, power and fatigue by isokinetic dynamometry, and mobility measured by the Short Physical Performance Battery and by gait velocity. The secondary outcome was health-related quality of life assessed by the SF-36 Questionnaire. Results The average rate of adherence was 85%, with few mild adverse effects. There were no significant between-group differences for any of the outcomes. Conclusion In this study, a progressive resistance exercise program with high-speed component was not effective for improving the physical function of older women with sarcopenic obesity. PMID:27410162

Muscle fatigue experienced during maximal eccentric exercise is predictive of the plasma creatine kinase (CK) response.

PubMed

Hody, S; Rogister, B; Leprince, P; Wang, F; Croisier, J-L

2013-08-01

Unaccustomed eccentric exercise may cause skeletal muscle damage with an increase in plasma creatine kinase (CK) activity. Although the wide variability among individuals in CK response to standardized lengthening contractions has been well described, the reasons underlying this phenomenon have not yet been understood. Therefore, this study investigated a possible correlation of the changes in muscle damage indirect markers after an eccentric exercise with the decline in muscle performance during the exercise. Twenty-seven healthy untrained male subjects performed three sets of 30 maximal isokinetic eccentric contractions of the knee extensors. The muscular work was recorded using an isokinetic dynamometer to assess muscle fatigue by means of various fatigue indices. Plasma CK activity, muscle soreness, and stiffness were measured before (pre) and one day after (post) exercise. The eccentric exercise bout induced significant changes of the three muscle damage indirect markers. Large inter-subject variability was observed for all criteria measured. More interestingly, the log (CK(post) /CK(pre)) and muscle stiffness appeared to be closely correlated with the relative work decrease (r = 0.84, r(2)  = 0.70 and r = 0.75, r(2)  = 0.56, respectively). This is the first study to propose that the muscle fatigue profile during maximal eccentric protocol could predict the magnitude of the symptoms associated with muscle damage in humans. © 2011 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Impact of Blood Flow Restriction Exercise on Muscle Fatigue Development and Recovery.

PubMed

Husmann, Florian; Mittlmeier, Thomas; Bruhn, Sven; Zschorlich, Volker; Behrens, Martin

2018-03-01

The present study was designed to provide mechanistic insight into the time course and etiology of muscle fatigue development and recovery during and after low-intensity exercise when it is combined with blood flow restriction (BFR). Seventeen resistance-trained males completed four sets of low-intensity isotonic resistance exercise under two experimental conditions: knee extension exercise (i) with BFR and (ii) without BFR (CON). Neuromuscular tests were performed before, during (immediately after each set of knee extension exercise), and 1, 2, 4, and 8 min after each experimental condition. Maximal voluntary torque, quadriceps twitch torque in response to paired electrical stimuli at 10 Hz (PS10) and 100 Hz (PS100), PS10·PS100 ratio as an index of low-frequency fatigue, and voluntary activation were measured under isometric conditions. Perceptual and EMG data were recorded during each exercise condition. After the first set of exercise, BFR induced significantly greater reductions in maximal voluntary torque, PS100, and PS10·PS100 ratio compared with CON. These parameters progressively declined throughout the BFR protocol but recovered substantially within 2 min postexercise when blood flow was restored. Neither a progressive decline in the course of the exercise protocol nor a substantial recovery of these parameters occurred during and after CON. Only at exercise termination, voluntary activation differed significantly between BFR and CON with greater reductions during BFR. At the early stage of exercise, BFR exacerbated the development of muscle fatigue mainly due to a pronounced impairment in contractile function. Despite the high level of muscle fatigue during BFR exercise, the effect of BFR on muscle fatigue was diminished after 2 min of reperfusion, suggesting that BFR has a strong but short-lasting effect on neuromuscular function.

Antigravity treadmill training during the early rehabilitation phase following unicompartmental knee arthroplasty: A case series.

PubMed

Huang, Chun-Hao; Schroeder, E Todd; Powers, Christopher

2018-02-26

Patients who have undergone unicompartmental knee arthroplasty (UKA) have been reported to exhibit altered gait 19-25 months post-surgery. The most common gait impairment in this population is inadequate knee flexion and a corresponding decrease in the knee extensor moment during loading response (i.e., quadriceps avoidance). The purpose of this case series was to determine whether incorporation of antigravity treadmill training into a standard physical therapy program can eliminate quadriceps avoidance gait during the early rehabilitation phase following UKA. Four females who underwent UKA were recruited for this study. Participants completed antigravity treadmill training three times per week for 12 weeks in addition to their standard physical therapy program. Instrumented gait analysis was performed at baseline (pre-intervention), week 6 (mid-intervention), and week 12 (post-intervention). We found that peak knee flexion and the peak knee extensor moment during the weight acceptance phase of gait increased to normal values following the 12-week intervention period (14.1 ± 6.5° to 20.6 ± 1.5° and 0.4 ± 0.3 to 0.7 ± 0.2 Nm/kg respectively). The findings of this case series suggest that a standard physical therapy program that incorporates early gait training using an antigravity treadmill may be beneficial in eliminating "quadriceps avoidance" during the early rehabilitation phase following UKA.

Adaptations in single-leg hop biomechanics following anterior cruciate ligament reconstruction.

PubMed

Orishimo, Karl F; Kremenic, Ian J; Mullaney, Michael J; McHugh, Malachy P; Nicholas, Stephen J

2010-11-01

When a patient performs a clinically normal hop test based on distance, it cannot be assumed that the biomechanics are similar between limbs. The objective was to compare takeoff and landing biomechanics between legs in patients who have undergone anterior cruciate ligament reconstruction. Kinematics and ground reaction forces were recorded as 13 patients performed the single-leg hop on each leg. Distance hopped, joint range of motion, peak joint kinetics and the peak total extensor moment were compared between legs during both takeoff and landing. Average hop distance ratio (involved/noninvolved) was 93 ± 4%. Compared to the noninvolved side, knee motion during takeoff on the involved side was significantly reduced (P = 0.008). Peak moments and powers on the involved side were lower at the knee and higher at the ankle and hip compared with the noninvolved side (Side by Joint P = 0.011; P = 0.003, respectively). The peak total extensor moment was not different between legs (P = 0.305) despite a decrease in knee moment and increases in ankle and hip moments (Side by Joint P = 0.015). During landing, knee motion was reduced (P = 0.043), and peak power absorbed was decreased at the knee and hip and increased at the ankle on the involved side compared to the noninvolved side (P = 0.003). The compensations by other joints may indicate protective adaptations to avoid overloading the reconstructed knee.

Phosphocreatine resynthesis during recovery in different muscles of the exercising leg by 31P-MRS.

PubMed

Yoshida, T; Abe, D; Fukuoka, Y

2013-10-01

To investigate the high-energy phosphate metabolism by (31) P-nuclear magnetic resonance spectroscopy during off-transition of exercise in different muscle groups, such as calf muscles and biceps femoris muscles, seven male long-distance runners (LDR) and nine untrained males (UT) performed both submaximal constant and incremental exercises. The relative exercise intensity was set at 60% of the maximal work rate (60%W max) during both knee flexion and plantar flexion submaximal constant load exercises. The relative areas under the inorganic phosphate (Pi ) and phosphocreatine (PCr) peaks were determined. During the 5-min recovery following the 60%W max, the time constant for the PCr off-kinetics was significantly faster in the plantar flexion (LDR: 17.3 ± 3.6 s, UT: 26.7 ± 6.7 s) than in the knee flexion (LDR: 29.7 ± 4.7 s, UT: 42.7 ± 2.8 s, P < 0.05). In addition, a significantly faster PCr off-kinetics was observed in LDR than in UT for both exercises. The ratio of Pi to PCr (Pi /PCr) during exercise was significantly lower during the plantar flexion than during the knee flexion (P < 0.01). These findings indicated that the calf muscles had relatively higher potential for oxidative capacity than that of biceps femoris muscles with an association of training status. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Neck muscle strain when wearing helmet and NVG during acceleration on a trampoline.

PubMed

Sovelius, Roope; Oksa, Juha; Rintala, Harri; Huhtala, Heini; Siitonen, Simo

2008-02-01

The helmet-mounted equipment worn by military pilots increases the weight of the helmet system and shifts its center of gravity, increasing the loads on neck structures, especially during acceleration. The aim of this study was to determine neck muscle strain with different head-loads during trampoline-induced G loads (0 to +4 G). Under three conditions [no helmet, helmet, helmet with night vision goggles (NVG)], 14 subjects performed trampoline exercises including basic, hand-and-knee, and back bouncing. EMG activity was measured for the sternocleidomastoid (SCM), cervical erector spinae (CES), trapezoid (TRA), and thoracic erector spinae (TES) muscles. Muscle strain was determined as a percentage of maximal voluntary contraction (%MVC). For the three exercises combined, the following significant changes were found: compared to control, the helmet increased muscle strain by 18%, 28%, and 18% in the SCM, CES, and TRA, respectively; NVG produced a further increase of 11% in the SCM and 6% in the CES. During back bouncing, the helmet increased muscle strain by 14% in the SCM and 19% in the CES, and NVG further increased this strain by 14% in the SCM. Hand-and-knee bouncing loaded extensors: the helmet caused increases of 46% in the CES and 29% in the TES, while NVG produced a further 13% increase in CES activation. Helmet weight alone had a large effect on muscular workload. The additional frontal weight of the NVG caused a further increase in the activity of cervical muscles that were already subjected to high strain.

Resistance exercise improves muscle strength, health status and pain intensity in fibromyalgia--a randomized controlled trial.

PubMed

Larsson, Anette; Palstam, Annie; Löfgren, Monika; Ernberg, Malin; Bjersing, Jan; Bileviciute-Ljungar, Indre; Gerdle, Björn; Kosek, Eva; Mannerkorpi, Kaisa

2015-06-18

Fibromyalgia (FM) is characterized by persistent widespread pain, increased pain sensitivity and tenderness. Muscle strength in women with FM is reduced compared to healthy women. The aim of this study was to examine the effects of a progressive resistance exercise program on muscle strength, health status, and current pain intensity in women with FM. A total of 130 women with FM (age 22-64 years, symptom duration 0-35 years) were included in this assessor-blinded randomized controlled multi-center trial examining the effects of progressive resistance group exercise compared with an active control group. A person-centred model of exercise was used to support the participants' self-confidence for management of exercise because of known risks of activity-induced pain in FM. The intervention was performed twice a week for 15 weeks and was supervised by experienced physiotherapists. Primary outcome measure was isometric knee-extension force (Steve Strong®), secondary outcome measures were health status (FIQ total score), current pain intensity (VAS), 6MWT, isometric elbow-flexion force, hand-grip force, health related quality of life, pain disability, pain acceptance, fear avoidance beliefs, and patient global impression of change (PGIC). Outcomes were assessed at baseline and immediately after the intervention. Long-term follow up comprised the self-reported questionnaires only and was conducted after 13-18 months. Between-group and within-group differences were calculated using non-parametric statistics. Significant improvements were found for isometric knee-extension force (p = 0.010), health status (p = 0.038), current pain intensity (p = 0.033), 6MWT (p = 0.003), isometric elbow flexion force (p = 0.02), pain disability (p = 0.005), and pain acceptance (p = 0.043) in the resistance exercise group (n = 56) when compared to the control group (n = 49). PGIC differed significantly (p = 0.001) in favor of the resistance exercise group at post-treatment examinations. No significant differences between the resistance exercise group and the active control group were found regarding change in self-reported questionnaires from baseline to 13-18 months. Person-centered progressive resistance exercise was found to be a feasible mode of exercise for women with FM, improving muscle strength, health status, and current pain intensity when assessed immediately after the intervention. ClinicalTrials.gov identification number: NCT01226784, Oct 21, 2010.

Effects of proprioceptive circuit exercise on knee joint pain and muscle function in patients with knee osteoarthritis.

PubMed

Ju, Sung-Bum; Park, Gi Duck; Kim, Sang-Soo

2015-08-01

[Purpose] This study applied proprioceptive circuit exercise to patients with degenerative knee osteoarthritis and examined its effects on knee joint muscle function and the level of pain. [Subjects] In this study, 14 patients with knee osteoarthritis in two groups, a proprioceptive circuit exercise group (n = 7) and control group (n = 7), were examined. [Methods] IsoMed 2000 (D&R Ferstl GmbH, Hemau, Germany) was used to assess knee joint muscle function, and a Visual Analog Scale was used to measure pain level. [Results] In the proprioceptive circuit exercise group, knee joint muscle function and pain levels improved significantly, whereas in the control group, no significant improvement was observed. [Conclusion] A proprioceptive circuit exercise may be an effective way to strengthen knee joint muscle function and reduce pain in patients with knee osteoarthritis.

Influence of variable resistance loading on subsequent free weight maximal back squat performance.

PubMed

Mina, Minas A; Blazevich, Anthony J; Giakas, Giannis; Kay, Anthony D

2014-10-01

The purpose of the study was to determine the potentiating effects of variable resistance (VR) exercise during a warm-up on subsequent free-weight resistance (FWR) maximal squat performance. In the first session, 16 recreationally active men (age = 26.0 ± 7.8 years; height = 1.7 ± 0.2 m; mass = 82.6 ± 12.7 kg) were familiarized with the experimental protocols and tested for 1 repetition maximum (1RM) squat lift. The subjects then visited the laboratory on 2 further occasions under either control or experimental conditions. During these conditions, 2 sets of 3 repetitions of either FWR (control) or VR (experimental) squat lifts at 85% of 1RM were performed; during the experimental condition, 35% of the load was generated from band tension. After a 5-minute rest, 1RM, 3D knee joint kinematics, and vastus medialis, vastus lateralis, rectus femoris, and semitendinosus electromyogram (EMG) signals were recorded simultaneously. No subject increased 1RM after FWR, however, 13 of 16 (81%) subjects increased 1RM after VR (mean = 7.7%; p < 0.01). Lower peak and mean eccentric (16-19%; p ≤ 0.05) and concentric (12-21%; p ≤ 0.05) knee angular velocities were observed during the 1RM following VR when compared with FWR, however, no differences in knee flexion angle (1.8°; p > 0.05) or EMG amplitudes (mean = 5.9%; p > 0.05) occurred. Preconditioning using VR significantly increased 1RM without detectable changes in knee extensor muscle activity or knee flexion angle, although eccentric and concentric velocities were reduced. Thus, VR seems to potentiate the neuromuscular system to enhance subsequent maximal lifting performance. Athletes could thus use VR during warm-up routines to maximize squat performance.

Atorvastatin Increases Exercise Leg Blood Flow in Healthy Adults

PubMed Central

Parker, Beth A.; Capizzi, Jeffrey A.; Augeri, Amanda L.; Grimaldi, Adam S.; White, C. Michael; Thompson, Paul D.

2011-01-01

OBJECTIVES We sought to examine the effect of atorvastatin therapy on exercise leg blood flow in healthy middle-aged and older, men and women. BACKGROUND The vasodilatory response to exercise decreases in humans with aging and disease and this reduction may contribute to reduced exercise capacity. METHODS We used a double-blind, randomly assigned, placebo-controlled protocol to assess the effect of atorvastatin treatment on exercising leg hemodynamics. We measured femoral artery blood flow (FBF) using Doppler ultrasound and calculated femoral vascular conductance (FVC) from brachial mean arterial pressure (MAP) before and during single knee-extensor exercise in healthy adults (ages 40–71) before (PRE) and after (POST) 6 months of 80 mg atorvastatin (A: 14 men, 16 women) or placebo (P: 14 men, 22 women) treatment. FBF and FVC were normalized to exercise power output and estimated quadriceps muscle mass. RESULTS Atorvastatin reduced LDL cholesterol by approximately 50%, but not in the placebo group (p < 0.01). Atorvastatin also increased exercise FBF from 44.2 ± 19.0 to 51.4 ± 22.0 mL/min/W/kg muscle whereas FBF in the placebo group was unchanged (40.1 ± 16.0 vs 39.5 ± 16.1) (p <0.01). FVC also increased with atorvastatin from 0.5 ± 0.2 to. 0.6 ± 0.2 mL/min/mmHg/W/kg muscle, but not in the placebo subjects (P: 0.4 ± 0.2 vs 0.4 ± 0.2) ( p < 0.01). CONCLUSIONS High-dose atorvastatin augments exercising leg hyperemia. Statins may mitigate reductions in the exercise vasodilatory response in humans that are associated with aging and disease. PMID:22018642

Effect of immobilization and retraining on torque-velocity relationship of human knee flexor and extensor muscles.

PubMed

Labarque, V L; Eijnde, B Op 't; Van Leemputte, M

2002-01-01

The effect of 2 weeks immobilization of the uninjured right knee and 10 weeks of retraining on muscle torque-velocity characteristics was investigated in nine young subjects. Left and right knee extension and flexion maximal voluntary isometric torque (Tmax) and dynamic torque at 60 degrees s(-1) (T60) and 180 degrees x s(-1) (T180) were measured before (PRE) and after immobilization (POST) and after 3 (R3) and 10 (R10) weeks of dynamic retraining. The torque-velocity relationship was quantified by expressing T60 and T180 relative to Tmax (NT60 and NT180, respectively). For the right extensor muscles, percutaneous biopsy samples were obtained from the vastus lateralis muscle and fibre type distribution was measured. POST extension and flexion torque (mean of Tmax, T60 and T180) decreased by 27% and 11%, respectively. During the course of the experiment, the changes in NT60 and NT180 were similar. POST extensor muscle NTV (mean of NT60 and NT180) was decreased significantly (12%, P<0.05), but no significant change was found for flexor muscle NTV (+ 3%). At R3 Tmax, dynamic torque and NTV were restored to normal. Unlike isometric torque, NTV did not change from R3 to R10. No changes in fibre type distribution were found. The adaptation of muscle length is suggested as the mechanism to explain the change in NTV.

Neuromuscular fatigue following isometric contractions with similar torque time integral.

PubMed

Rozand, V; Cattagni, T; Theurel, J; Martin, A; Lepers, R

2015-01-01

Torque time integral (TTI) is the combination of intensity and duration of a contraction. The aim of this study was to compare neuromuscular alterations following different isometric sub-maximal contractions of the knee extensor muscles but with similar TTI. Sixteen participants performed 3 sustained contractions at different intensities (25%, 50%, and 75% of Maximal Voluntary Contraction (MVC) torque) with different durations (68.5±33.4 s, 35.1±16.8 s and 24.8±12.9 s, respectively) but similar TTI value. MVC torque, maximal voluntary activation level (VAL), M-wave characteristics and potentiated doublet amplitude were assessed before and immediately after the sustained contractions. EMG activity of the vastus lateralis (VL) and -rectus femoris (RF) muscles was recorded during the sustained contractions. MVC torque reduction was similar in the 3 conditions after the exercise (-23.4±2.7%). VAL decreased significantly in a similar extent (-3.1±1.3%) after the 3 sustained contractions. Potentiated doublet amplitude was similarly reduced in the 3 conditions (-19.7±1.5%), but VL and RF M-wave amplitudes remained unchanged. EMG activity of VL and RF muscles increased in the same extent during the 3 contractions (VL: 54.5±40.4%; RF: 53.1±48.7%). These results suggest that central and peripheral alterations accounting for muscle fatigue are similar following isometric contractions with similar TTI. TTI should be considered in the exploration of muscle fatigue during sustained isometric contractions. © Georg Thieme Verlag KG Stuttgart · New York.

Relationship between cardiopulmonary responses and isokinetic moments: the optimal angular velocity for muscular endurance

PubMed Central

Lee, Chan-Bok; Eun, Denny; Kim, Kang-Ho; Park, Jae-Wan; Jee, Yong-Seok

2017-01-01

Most protocols for testing and rehabilitation for recovery and improvement of muscular endurance have been set at 180°/sec, 240°/sec, and 300°/sec. These protocols can cause confusion to clinical providers or other researchers. This study was aimed at investigating the optimal isokinetic angular speed for measuring or developing muscular endurance after assessing the relationship between cardiopulmonary responses and isokinetic moments. This study was conducted with 31 male and female college students. Graded exercise test and body composition were measured as well as the isokinetic moments of the knee muscles at three angular speeds: 180°/sec, 240°/sec, and 300°/sec. The specific isokinetic moments of knee muscles that were measured included: peak torque (PT) and total work (TW) on extensor (e) and flexor (f) of knee joints, which were denoted as ePT180, fPT180, eTW180, fTW180, ePT240, fPT240, eTW240, fTW240, ePT300, fPT300, eTW300, and fTW300 according to the three angular speeds. Spearman correlation test was used to examine the relationship between the sum means of cardiopulmonary responses and the variables of isokinetic moments. This study confirmed that the optimal angular speed for testing or training for muscular endurance was 180°/sec, which showed a stronger relationship between cardiopulmonary responses and isokinetic moments. Therefore, this angular speed is recommended for testing and training for muscular endurance of the knee joints. PMID:28503531

Relationship between cardiopulmonary responses and isokinetic moments: the optimal angular velocity for muscular endurance.

PubMed

Lee, Chan-Bok; Eun, Denny; Kim, Kang-Ho; Park, Jae-Wan; Jee, Yong-Seok

2017-04-01

Most protocols for testing and rehabilitation for recovery and improvement of muscular endurance have been set at 180°/sec, 240°/sec, and 300°/sec. These protocols can cause confusion to clinical providers or other researchers. This study was aimed at investigating the optimal isokinetic angular speed for measuring or developing muscular endurance after assessing the relationship between cardiopulmonary responses and isokinetic moments. This study was conducted with 31 male and female college students. Graded exercise test and body composition were measured as well as the isokinetic moments of the knee muscles at three angular speeds: 180°/sec, 240°/sec, and 300°/sec. The specific isokinetic moments of knee muscles that were measured included: peak torque (PT) and total work (TW) on extensor (e) and flexor (f) of knee joints, which were denoted as ePT180, fPT180, eTW180, fTW180, ePT240, fPT240, eTW240, fTW240, ePT300, fPT300, eTW300, and fTW300 according to the three angular speeds. Spearman correlation test was used to examine the relationship between the sum means of cardiopulmonary responses and the variables of isokinetic moments. This study confirmed that the optimal angular speed for testing or training for muscular endurance was 180°/sec, which showed a stronger relationship between cardiopulmonary responses and isokinetic moments. Therefore, this angular speed is recommended for testing and training for muscular endurance of the knee joints.

Serratus anterior and lower trapezius muscle activities during multi-joint isotonic scapular exercises and isometric contractions.

PubMed

Tsuruike, Masaaki; Ellenbecker, Todd S

2015-02-01

Proper scapular function during humeral elevation, such as upward rotation, external rotation, and posterior tilting of the scapula, is necessary to prevent shoulder injury. However, the appropriate intensity of rehabilitation exercise for the periscapular muscles has yet to be clarified. To identify the serratus anterior, lower trapezius, infraspinatus, and posterior deltoid muscle activities during 2 free-motion exercises using 3 intensities and to compare these muscle activities with isometric contractions during quadruped shoulder flexion and external rotation and abduction of the glenohumeral joint. Cross-sectional study. Health Science Laboratory. A total of 16 uninjured, healthy, active, male college students (age = 19.5 ± 1.2 years, height = 173.1 ± 6.5 cm, weight = 68.8 ± 6.6 kg). Mean electromyographic activity normalized by the maximal voluntary isometric contraction was analyzed across 3 intensities and 5 exercises. Intraclass correlation coefficients were calculated for electromyographic activity of the 4 muscles in each free-motion exercise. Significant interactions in electromyographic activity were observed between intensities and exercises (P < .05). The quadruped shoulder-flexion exercise activated all 4 muscles compared with other exercises. Also, the modified robbery free-motion exercise activated the serratus anterior, lower trapezius, and infraspinatus compared with the lawn-mower free-motion exercise. However, neither exercise showed a difference in posterior deltoid electromyographic activity. Three intensities exposed the nature of the periscapular muscle activities across the different exercises. The free-motion exercise in periscapular muscle rehabilitation may not modify serratus anterior, lower trapezius, and infraspinatus muscle activities unless knee-joint extension is limited.

[Isokinetic profile of knee flexors and extensors in a population of rugby players].

PubMed

Larrat, E; Kemoun, G; Carette, P; Teffaha, D; Dugue, B

2007-06-01

We aimed to assess the isokinetic profile of the flexor and extensor muscles of the knee within a population of rugby players. This was a descriptive study. The rugby players underwent bilateral isokinetic assessment of knee flexion and extension on a CON-TREX MJ isokinetic dynamometer functioning at four angular frequencies - 90, 120, 180 and 240 degrees/s - in a concentric manner. The isokinetic parameters were peak torque, mean power, and mean work in relation to weight and femoral bicep: quadriceps ratio. The population included 16 "Federal 1" (semi-professional) rugby players with mean age 25 years (range 20-33 years). The players were divided into two groups: "forward" players (props, hookers, second line, third line) and "back" players (scrum, inside, center, wing, tail). The values of the isokinetic parameters did not reveal use of a preferred limb. Consequently, peak torque and mean power were higher in forward players than back players, whereas back players showed a higher relative power throughout the isokinetic test. Among rugby players, forward and back players showed differences in several isokinetic parameters. Accurate knowledge of the equilibrium between the knee's effector muscles is important for stability of the joint, to not only minimize articular accidents but also pinpoint force imbalances, thereby preventing muscular lesions during the sports season.

Analysis of lower limb work-energy patterns in world-class race walkers.

PubMed

Hanley, Brian; Bissas, Athanassios

2017-05-01

The aim of this study was to analyse lower limb work patterns in world-class race walkers. Seventeen male and female athletes race walked at competitive pace. Ground reaction forces (1000 Hz) and high-speed videos (100 Hz) were recorded and normalised joint moments, work and power, stride length, stride frequency and speed estimated. The hip flexors and extensors were the main generators of energy (24.5 J (±6.9) and 40.3 J (±8.3), respectively), with the ankle plantarflexors (16.3 J (±4.3)) contributing to the energy generated during late stance. The knee generated little energy but performed considerable negative work during swing (-49.1 J (±8.7)); the energy absorbed by the knee extensors was associated with smaller changes in velocity during stance (r = .783, P < .001), as was the energy generated by the hip flexors (r = -.689, P = .002). The knee flexors did most negative work (-38.6 J (±5.8)) and the frequent injuries to the hamstrings are probably due to this considerable negative work. Coaches should note the important contributions of the hip and ankle muscles to energy generation and the need to develop knee flexor strength in reducing the risk of injury.

Effects of resistance exercise training and nandrolone decanoate on body composition and muscle function among patients who receive hemodialysis: A randomized, controlled trial.

PubMed

Johansen, Kirsten L; Painter, Patricia L; Sakkas, Giorgos K; Gordon, Patricia; Doyle, Julie; Shubert, Tiffany

2006-08-01

Patients who are on hemodialysis commonly experience muscle wasting and weakness, which have a negative effect on physical functioning and quality of life. The objective of this study was to determine whether anabolic steroid administration and resistance exercise training induce anabolic effects among patients who receive maintenance hemodialysis. A randomized 2 x 2 factorial trial of anabolic steroid administration and resistance exercise training was conducted in 79 patients who were receiving maintenance hemodialysis at University of California, San Francisco-affiliated dialysis units. Interventions included double-blinded weekly nandrolone decanoate (100 mg for women; 200 mg for men) or placebo injections and lower extremity resistance exercise training for 12 wk during hemodialysis sessions three times per week using ankle weights. Primary outcomes included change in lean body mass (LBM) measured by dual-energy x-ray absorptiometry, quadriceps muscle cross-sectional area measured by magnetic resonance imaging, and knee extensor muscle strength. Secondary outcomes included changes in physical performance, self-reported physical functioning, and physical activity. Sixty-eight patients completed the study. Patients who received nandrolone decanoate increased their LBM by 3.1 +/- 2.2 kg (P < 0.0001). Exercise did not result in a significant increase in LBM. Quadriceps muscle cross-sectional area increased in patients who were assigned to exercise (P = 0.01) and to nandrolone (P < 0.0001) in an additive manner. Patients who exercised increased their strength in a training-specific fashion, and exercise was associated with an improvement in self-reported physical functioning (P = 0.04 compared with nonexercising groups). Nandrolone decanoate and resistance exercise produced anabolic effects among patients who were on hemodialysis. Further studies are needed to determine whether these interventions improve survival.

Effects of squat lift training and free weight muscle training on maximum lifting load and isolinetic peak torque of young adults without impairments.

PubMed

Yeung, S S; Ng, G Y

2000-06-01

Manual lifting is a frequent cause of back injury, and there is no evidence as to which training mode can provide the best training effect for lifting performance and muscle force. The purpose of this study was to examine the effects of a squat lift training and a free weight muscle training program on the maximum lifting load and isokinetic peak torque in subjects without known neuromuscular or musculoskeletal impairments. Thirty-six adults (20 male, 16 female) without known neuromuscular or musculoskeletal impairments participated. The subjects' mean age was 21.25 years (SD=1.16, range=20-24). Subjects were divided into 3 groups. Subjects in group 1 (n=12) performed squat lift training. Subjects in group 2 (n=12) participated in free weight resistance training of their shoulder abductors, elbow flexors, knee extensors and trunk extensors. Subjects in group 3 (n=12) served as controls. The maximum lifting load and isokinetic peak torques of the trunk extensors, knee extensors, elbow flexors, and shoulder abductors of each subject were measured before and after the study. Training was conducted on alternate days for 4 weeks, with an initial load of 80% of each subject's maximum capacity and with the load increased by 5% weekly. All groups were comparable for all measured variables before the study. After 4 weeks, subjects in groups 1 and 2 demonstrated more improvement in maximum lifting load and isokinetic peak torque of the back extensors compared with the subjects in group 3, but the 2 training groups were not different. The findings demonstrate that both squat lift and free weight resistance training are equally effective in improving the lifting load and isokinetic back extension performance of individuals without impairments.

Characteristics and Preliminary Observations of the Influence of Electromyostimulation on the Size and Function of Human Skeletal Muscle During 30 Days of Simulated Microgravity

NASA Technical Reports Server (NTRS)

Duvoisin, Marc R.; Convertino, Victor A; Buchanan, Paul; Gollinick, Philip D.; Dudley, Gary A.

1989-01-01

During 30 days (d) of bedrest, the practicality of using Elec- troMyoStimulation (EMS) as a deterrent to atrophy and strength loss of lower limb musculature was examined. An EMS system was developed that provided variable but quantifiable levels of EMS, and measured torque. The dominant log of three male subjects was stimulated twice daily in a 3-d on/1-d off cycle during bedrest. The non-dominant leg of each subject acted as a control. A stimulator, using a 0.3 ms monophasic 60 Hz pulse waveform, activated muscle tissue for 4 s. The output waveform from the stimulator was sequenced to the Knee Extensors (KE), Knee Flex- ors (KF), Ankle Extensors (AE), and Ankle Flexors (AF), and caused three isometric contractions of each muscle group per minute. Subject tolerance determined EMS Intensity. Each muscle group received four 5-min bouts of EMS each session with a 10 -min rest between bouts. EMS and torque levels for each muscle action were recorded directly an a computer. Overall average EMS Intensity was 197, 197, 195, and 188 mA for the KE, KF, AF, and AE, respectively. Overall average torque development for these muscle groups was 70, 16, 12, and 27 Nm, respectively. EMS intensity doubled during the study, and average torque increased 2.5 times. Average maximum torque throughout a session reached 54% of maximal voluntary for the KE and 29% for the KF. Reductions in leg volume, muscle compartment size, cross-sectional area of slow and fast-twitch fibers, strength, and aerobic enzyme activities, and increased log compliance were attenuated in the legs which received EMS during bedrest. These results indicate that similar EMS levels induce different torques among different muscle groups and that repeated exposure to EMS increases tolerance and torque development. Longer orien- tation periods, therefore, may enhance its effectiveness. Our preliminary data suggest that the efficacy of EMS as an effective countermeasure for muscle atrophy and strength loss during long duration space travel warrants further investigation.

Work-Related Pain in Extrinsic Finger Extensor Musculature of Instrumentalists Is Associated with Intracellular pH Compartmentation during Exercise

PubMed Central

Moreno-Torres, Angel; Rosset-Llobet, Jaume; Pujol, Jesus; Fàbregas, Sílvia; Gonzalez-de-Suso, Jose-Manuel

2010-01-01

Background Although non-specific pain in the upper limb muscles of workers engaged in mild repetitive tasks is a common occupational health problem, much is unknown about the associated structural and biochemical changes. In this study, we compared the muscle energy metabolism of the extrinsic finger extensor musculature in instrumentalists suffering from work-related pain with that of healthy control instrumentalists using non-invasive phosphorus magnetic resonance spectroscopy (31P-MRS). We hypothesize that the affected muscles will show alterations related with an impaired energy metabolism. Methodology/Principal Findings We studied 19 volunteer instrumentalists (11 subjects with work-related pain affecting the extrinsic finger extensor musculature and 8 healthy controls). We used 31P-MRS to find deviations from the expected metabolic response to exercise in phosphocreatine (PCr), inorganic phosphate (Pi), Pi/PCr ratio and intracellular pH kinetics. We observed a reduced finger extensor exercise tolerance in instrumentalists with myalgia, an intracellular pH compartmentation in the form of neutral and acid compartments, as detected by Pi peak splitting in 31P-MRS spectra, predominantly in myalgic muscles, and a strong association of this pattern with the condition. Conclusions/Significance Work-related pain in the finger extrinsic extensor muscles is associated with intracellular pH compartmentation during exercise, non-invasively detectable by 31P-MRS and consistent with the simultaneous energy production by oxidative metabolism and glycolysis. We speculate that a deficit in energy production by oxidative pathways may exist in the affected muscles. Two possible explanations for this would be the partial and/or local reduction of blood supply and the reduction of the muscle oxidative capacity itself. PMID:20161738

Effect of an eccentrically biased hamstring strengthening home program on knee flexor strength and the length-tension relationship.

PubMed

Orishimo, Karl F; McHugh, Malachy P

2015-03-01

The purposes of this study were to document relative activation intensities of the hamstrings and gluteus maximus during 4 eccentric hamstring strengthening exercises and to assess the effects of a short-term strengthening program comprised of these exercises on knee flexor strength and the length-tension relationship. Twelve healthy subjects participated in this study. Electromyographic (EMG) activities from the biceps femoris, semitendinosus, and gluteus maximus were recorded as subjects performed (a) standing hip extension with elastic resistance, (b) trunk flexion in single limb stance (diver), (c) standing split (glider), and (d) supine sliding bridge (slider). Baseline isometric knee flexor strength was measured at 90, 70, 50, and 30° of flexion at the knee with the subject seated and the hip flexed to 50° from horizontal. After completing the 4-week training program, strength tests were repeated. Repeated-measures analysis of variance were used to compare EMG activity between muscles and to assess angle-specific strength improvements. Hamstring activity exceeded gluteus maximus activity for resisted hip extension, glider, and slider exercises (p < 0.001) but not for the diver (p = 0.087). Hamstring activation was greatest during the slider and resisted hip extension and lowest during the glider and the diver. Knee flexor strength improved by 9.0% (p = 0.005) but was not angle specific (training by angle p = 0.874). The short-term home training program effectively targeted the hamstrings and resulted in strength gains that were similar at short and long muscle lengths. These data demonstrate that hamstring strength can be improved using eccentrically biased unilateral exercises without the use of weights or other equipments.

Adaptations to Short, Frequent Sessions of Endurance and Strength Training Are Similar to Longer, Less Frequent Exercise Sessions When the Total Volume Is the Same.

PubMed

Kilen, Anders; Hjelvang, Line B; Dall, Niels; Kruse, Nanna L; Nordsborg, Nikolai B

2015-11-01

The hypothesis that the distribution of weekly training across several short sessions, as opposed to fewer longer sessions, enhances maximal strength gain without compromising maximal oxygen uptake was evaluated. Twenty-nine subjects completed an 8-week controlled parallel-group training intervention. One group ("micro training" [MI]: n = 21) performed nine 15-minute training sessions weekly, whereas a second group ("classical training" [CL]: n = 8) completed exactly the same training on a weekly basis but as three 45-minute sessions. For each group, each session comprised exclusively strength, high-intensity cardiovascular training or muscle endurance training. Both groups increased shuttle run performance (MI: 1,373 ± 133 m vs. 1,498 ± 126 m, p ≤ 0.05; CL: 1,074 ± 213 m vs. 1,451 ± 202 m, p < 0.001). In contrast to CL, MI increased peak oxygen uptake (3,744 ± 615 mL·min⁻¹ vs. 3,963 ± 753 mL·min⁻¹, p ≤ 0.05), maximal voluntary isometric (MVC) force of the knee extensors (646 ± 135 N vs. 659 ± 209 N, p < 0.001), MVC of the finger flexors (408 ± 109 N vs. 441 ± 131 N, p ≤ 0.05), and number of lunges performed in 2 minutes (65 ± 3 vs. 73 ± 2, p < 0.001). However, there were no significant differences between MI and CL on any measured parameters before or after the training intervention. In conclusion, similar training adaptations can be obtained with short, frequent exercise sessions or longer, less frequent sessions where the total volume of weekly training performed is the same.

[Patella fractures in knee arthroplasty].

PubMed

Roth, A; Ghanem, M; Fakler, J

2016-05-01

Periprosthetic patella fractures occur both with and without retropatellar joint replacement. A non-operative treatment yields satisfactory results with low morbidity. It can be applied in minimally displaced fractures that have an intact retropatellar component and an intact extensor mechanism, combined with an initial immobilization. The surgical treatment is associated with relatively poor results and with high complication rates. There was only minor improvement of functional results, no matter which surgical technique was used. Surgical intervention is still required in fractures with a loosening of the patellar component, considerable dislocations of fragments, and damage to or rupture of the extensor mechanism. In particular, type II fractures require repair of the extensor mechanism and the fracture or patellectomy. Type III fractures require a revision or resection of the patella, a patelloplasty or total patellectomy. In addition, early or late reconstruction using allograft to restore the extensor mechanism can be taken in consideration.

Effects of Ramadan intermittent fasting on middle-distance running performance in well-trained runners.

PubMed

Brisswalter, Jeanick; Bouhlel, Ezzedine; Falola, Jean Marie; Abbiss, Christopher R; Vallier, Jean Marc; Hausswirth, Christophe; Hauswirth, Christophe

2011-09-01

To assess whether Ramadan intermittent fasting (RIF) affects 5000-m running performance and physiological parameters classically associated with middle-distance performance. Two experimental groups (Ramadan fasting, n = 9, vs control, n = 9) participated in 2 experimental sessions, one before RIF and the other at the last week of fasting. For each session, subjects completed 4 tests in the same order: a maximal running test, a maximal voluntary contraction (MVC) of knee extensor, 2 rectangular submaximal exercises on treadmill for 6 minutes at an intensity corresponding to the first ventilatory threshold (VT1), and a running performance test (5000 m). Eighteen, well-trained, middle-distance runners. Maximal oxygen consumption, MVC, running performance, running efficiency, submaximal VO(2) kinetics parameters (VO(2), VO(2)b, time constant τ, and amplitude A1) and anthropometric parameters were recorded or calculated. At the end of Ramadan fasting, a decrease in MVC was observed (-3.2%; P < 0.00001; η, 0.80), associated with an increase in the time constant of oxygen kinetics (+51%; P < 0.00007; η, 0.72) and a decrease in performance (-5%; P < 0.0007; η, 0.51). No effect was observed on running efficiency or maximal aerobic power. These results suggest that Ramadan changes in muscular performance and oxygen kinetics could affect performance during middle-distance events and need to be considered to choose training protocols during RIF.

Selective fatigue of fast motor units after electrically elicited muscle contractions.

PubMed

Hamada, Taku; Kimura, Tetsuya; Moritani, Toshio

2004-10-01

The aim of the present study was to elucidate the electrophysiological manifestations of selective fast motor unit (MU) activation by electrical stimulation (ES) of knee extensor muscles. In six male subjects, test contraction measurement at 40% maximal voluntary contraction (MVC) was performed before and at every 5 min (5, 10, 15 and 20 min) during 20-min low intensity intermittent exercise of either ES or voluntary contractions (VC) at 10% MVC (5-s isometric contraction and 5-s rest cycles). Both isolated intramuscular MU spikes obtained from three sets of bipolar fine-wire electrodes and surface electromyogram (EMG) were simultaneously recorded and were analyzed by means of a computer-aided intramuscular spike amplitude-frequency analysis and frequency power spectral analysis, respectively. Results indicated that mean MU spike amplitude, particularly those MUs with relatively large amplitude, was significantly reduced while those MUs with small spike amplitude increased their firing rate during the 40% MVC test contraction after the ES. This was accompanied by the increased amplitude of surface EMG (rmsEMG). However, no such significant changes in the intramuscular and surface EMGs were observed after VC. These findings indicated differential MU activation patterns in terms of MU recruitment and rate coding characteristics during ES and VC, respectively. Our data strongly suggest the possibility of "an inverse size principle" of MU recruitment during ES.

Effect of adding one 15-minute-walk on the day of surgery to fast-track rehabilitation after total knee arthroplasty: a randomized, single-blind study.

PubMed

Zietek, P; Zietek, J; Szczypior, K; Safranow, K

2015-06-01

Earlier and more intensive physiotherapy exercise after total knee arthroplasty (TKA) enhance recovery, but the best combination of intensity and duration has not been determined. To determine whether adding a single, 15-minute walk on the day of surgery to a fast-track rehabilitation protocol would reduce knee pain and improve knee function after TKA. A randomized single-blind study. Inpatient. Patients with primary osteoarthrosis after TKA. Patients undergoing TKA were randomly assigned to a standard, fast-track rehabilitation protocol consisting of a single, 15-minute walk with a high-rolling walker 4 to 6 hours after recovery from spinal anesthesia or to an intensive protocol, in which patients took a second 15-minute walk at least 3 hours after the first, only on the day of surgery. Outcomes were pain measured on a visual analog scale, Knee Society's (KSS) clinical and functional scores, Oxford knee scores, and Spielberger State-Trait Anxiety Inventory scores. Patients were blinded to group assignment. Since most data were non-normally distributed non-parametric tests were used. Groups were compared with Mann-Whitney U test (for continuous variables). Association between continuous variables was evaluated with Spearman`s rank correlation coefficient. Chi-square or Fisher's exact test was used to assess differences in categorical variables. Of 86 patients assessed for eligibility, 66 were randomly assigned. The 31 evaluable patients on the intensive protocol (mean age, 68 years; 18 women) did not differ significantly from the 31 (mean age, 70 years; 20 women) on the standard protocol on any baseline characteristic or on any outcome measure on any day. On the second postoperative day, pain while walking dropped from a mean of 6.1 to a mean of 4.9 in the intensive group and from 6.4 to 5.4 in the standard group. Results for pain at rest were 3.3 to 2.2, respectively, for the intensive group and 4.0 to 3.0 for the standard group. At 2 weeks, pain at rest was 2.8 in both groups, and pain while walking was 3.0, respectively, for the intensive group and 3.4 for the standard group. At 2 weeks, mean (SD) KSS clinical and KSS function scores were, respectively, 74.9 (12.5) and 51.6 (16.2) in the intensive group and 71.2 (14.3) and 46.3 (16.1) in the standard group. Older age correlated with decreasing knee function (rS=-0.43, P<0.001), and less knee flexion correlated with preoperatively higher state anxiety (rS=-0.37, P=0.005) and trait anxiety (rS=-0.29, P=0.027). The study is limited by its small sample. The fast-track program was not in line with the best available evidence following knee arthroplasty, because patients did not undergo such treatment as NMES. Finally, the intervention itself was modest. Adding an additional 15-minute walk to a fast-track rehabilitation protocol did not increase pain, but neither did it improve functional recovery. A 15-minute walk immediately after recovery from spinal anesthesia did not increase pain in patients with TKA. More intense exercise during this period might improve functional recovery without increasing pain.

Gait and balance of transfemoral amputees using passive mechanical and microprocessor-controlled prosthetic knees.

PubMed

Kaufman, K R; Levine, J A; Brey, R H; Iverson, B K; McCrady, S K; Padgett, D J; Joyner, M J

2007-10-01

Microprocessor-controlled knee joints appeared on the market a decade ago. These joints are more sophisticated and more expensive than mechanical ones. The literature is contradictory regarding changes in gait and balance when using these sophisticated devices. This study employed a crossover design to assess the comparative performance of a passive mechanical knee prosthesis compared to a microprocessor-controlled knee joint in 15 subjects with an above-knee amputation. Objective measurements of gait and balance were obtained. Subjects demonstrated significantly improved gait characteristics after receiving the microprocessor-controlled prosthetic knee joint (p<0.01). Improvements in gait were a transition from a hyperextended knee to a flexed knee during loading response which resulted in a change from an internal knee flexor moment to a knee extensor moment. The participants' balance also improved (p<0.01). All conditions of the Sensory Organization Test (SOT) demonstrated improvements in equilibrium score. The composite score also increased. Transfemoral amputees using a microprocessor-controlled knee have significant improvements in gait and balance.

Panax ginseng and Salvia miltiorrhiza supplementation during eccentric resistance training in middle-aged and older adults: A double-blind randomized control trial.

PubMed

Lin, Hsin-Fu; Chou, Chun-Chung; Chao, Hsiao-Han; Tanaka, Hirofumi

2016-12-01

Muscle damage induced by an acute bout of eccentric exercise results in transient arterial stiffening. In this study, we sought to determine the effects of progressive eccentric resistance exercise training on vascular functions, and whether herb supplementation would enhance training adaptation by ameliorating the arterial stiffening effects. By using a double-blinded randomized placebo-controlled design, older adults were randomly assigned to either the Panax ginseng and Salvia miltiorrhiza supplementation group (N=12) or the placebo group (N=11). After pre-training testing, all subjects underwent 12 weeks of unilateral eccentric-only exercise training on knee extensor. Maximal leg strength and muscle quality increased in both groups (P<0.05). Relative increases in muscle mass were significantly greater in the placebo group than in the herb supplement group. Eccentric exercise training did not elicit any significant changes in muscle damage, oxidative and inflammatory biomarkers. There were no significant changes in blood pressure or endothelium-dependent vasodilation. None of the measures of arterial stiffness changed significantly with eccentric resistance training in both groups. These results suggest that Chinese herb supplementation does not appear to modulate vascular, and inflammatory adaptations to eccentric exercise training in middle-aged and older adults. However, Chinese herb supplementation abolished the increase in muscle mass induced by eccentric resistance training. (Trial registration: ClinicalTrials.gov: NCT02007304. Registered Dec. 5, 2013). Copyright © 2016 Elsevier Ltd. All rights reserved.

Genome-wide linkage scan for maximum and length-dependent knee muscle strength in young men: significant evidence for linkage at chromosome 14q24.3.

PubMed

De Mars, G; Windelinckx, A; Huygens, W; Peeters, M W; Beunen, G P; Aerssens, J; Vlietinck, R; Thomis, M A I

2008-05-01

Maintenance of high muscular fitness is positively related to bone health, functionality in daily life and increasing insulin sensitivity, and negatively related to falls and fractures, morbidity and mortality. Heritability of muscle strength phenotypes ranges between 31% and 95%, but little is known about the identity of the genes underlying this complex trait. As a first attempt, this genome-wide linkage study aimed to identify chromosomal regions linked to muscle and bone cross-sectional area, isometric knee flexion and extension torque, and torque-length relationship for knee flexors and extensors. In total, 283 informative male siblings (17-36 years old), belonging to 105 families, were used to conduct a genome-wide SNP-based multipoint linkage analysis. The strongest evidence for linkage was found for the torque-length relationship of the knee flexors at 14q24.3 (LOD = 4.09; p<10(-5)). Suggestive evidence for linkage was found at 14q32.2 (LOD = 3.00; P = 0.005) for muscle and bone cross-sectional area, at 2p24.2 (LOD = 2.57; p = 0.01) for isometric knee torque at 30 degrees flexion, at 1q21.3, 2p23.3 and 18q11.2 (LOD = 2.33, 2.69 and 2.21; p<10(-4) for all) for the torque-length relationship of the knee extensors and at 18p11.31 (LOD = 2.39; p = 0.0004) for muscle-mass adjusted isometric knee extension torque. We conclude that many small contributing genes rather than a few important genes are involved in causing variation in different underlying phenotypes of muscle strength. Furthermore, some overlap in promising genomic regions were identified among different strength phenotypes.

Relationship between isometric thigh muscle strength and minimum clinically important differences in knee function in osteoarthritis: data from the osteoarthritis initiative.

PubMed

Ruhdorfer, Anja; Wirth, Wolfgang; Eckstein, Felix

2015-04-01

To determine the relationship between thigh muscle strength and clinically relevant differences in self-assessed lower leg function. Isometric knee extensor and flexor strength of 4,553 Osteoarthritis Initiative participants (2,651 women and 1,902 men) was related to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function scores by linear regression. Further, groups of male and female participant strata with minimum clinically important differences (MCIDs) in WOMAC function scores (6 of 68 units) were compared across the full range of observed values and to participants without functional deficits (WOMAC score 0). The effect of WOMAC knee pain and body mass index on the above relationships was explored using stepwise regression. Per regression equations, a 3.7% reduction in extensor strength and a 4.0% reduction in flexor strength were associated with an MCID in WOMAC function in women, and, respectively, a 3.6% and 4.8% reduction in men. For strength divided by body weight, reductions were 5.2% and 6.7%, respectively, in women and 5.8% and 6.7%, respectively, in men. Comparing MCID strata across the full observed range of WOMAC function confirmed the above estimates and did not suggest nonlinear relationships across the spectrum of observed values. WOMAC pain correlated strongly with WOMAC function, but extensor (and flexor) muscle strength contributed significant independent information. Reductions of approximately 4% in isometric muscle strength and of 6% in strength per body weight were related to a clinically relevant difference in WOMAC functional disability. Longitudinal studies will need to confirm these relationships within persons. Muscle extensor (and flexor) strength (per body weight) provided significant independent information in addition to pain in explaining variability in lower leg function. Copyright © 2015 by the American College of Rheumatology.

Joint Moment-Angle Properties of the Hip Extensors in Subjects With and Without Patellofemoral Pain.

PubMed

Kindel, Curtis; Challis, John

2018-04-01

Strength deficits of hip extension in individuals with patellofemoral syndrome are commonly reported in literature. No literature to date has examined these deficits with variable positions of the knee and hip; altering knee angle alters the length and therefore potentially the force produced by the biarticular muscles. Beyond strength, neuromuscular control can also be assessed through the analysis of isometric joint moment steadiness. Subjects consisted of a group of individuals with patellofemoral syndrome (n = 9), and a group of age- and size-matched controls with no symptoms (n = 9). Maximum isometric joint moments for hip extension were measured at 4 points within the joint's range of motion, at 2 different knee positions (0° and 90°) for each group. The joint moment signals were analyzed by computing signal Coefficient of Variation (CV). The results indicate that no significant differences were found between the groups of subjects for the hip extension moments when the knee was extended. However, there was a significant difference between the groups for the joint moments of hip extension with the knee flexed at all 4 hip positions. Results also showed hip extension CV values to be significantly higher in the patellofemoral group compared with the control group, indicating greater signal noise and therefore poorer neuromuscular control of the hip extensor musculature. This study demonstrated that individuals with patellofemoral syndrome have reduced hip extension strength and reduced neuromuscular control with the knee flexed compared with a control group. These results have implications for the etiology of patellofemoral syndrome and its rehabilitation.

Zapateado technique as an injury risk in Mexican folkloric and Spanish dance: an analysis of execution, ground reaction force, and muscle strength.

PubMed

Echegoyen, Soledad; Aoyama, Takeshi; Rodríguez, Cristina

2013-06-01

Zapateado is a repetitive percussive footwork in dance. This percussive movement, and the differences in technique, may be risk factors for injury. A survey on zapateado dance students found a rate of 1.5 injuries/1,000 exposures. Knee injuries are more frequent than in Spanish dancers than folkloric dancers. The aim of this research was to study the relationship between technique and ground reaction force between zapateado on Spanish and Mexican folkloric dancers. Ten female dance students (age 22.4 ± 4 yrs), six Spanish dancers and four Mexican folkloric dancers, were considered. Each student performed zapateado with a flat foot, wearing high-heeled shoes during 5 seconds on a force platform. Videotapes were taken on a lateral plane, and knee and hip angles in each movement phase were measured with Dartfish software. Additionally, knee and ankle flexor and extensor strength was measured with a dynamometer. Ground reaction forces were lower for Spanish dancers than Mexican folkloric dancers. Spanish dancers had less knee flexion when the foot contacted to the ground than did Mexican folkloric dancers. On Spanish dancers, the working leg had more motion in relation to hip and knee angles than was seen in folkloric dancers. The ankle extensors were stronger on folkloric dancers, and there were no differences for the other muscle groups. Knee flexion at foot contact and muscle strength imbalance could be risk factors for injuries. It is suggested that the technique in Spanish dance in Mexico be reviewed, although more studies are required to define more risk factors.

The effects of lumbar extensor strength on disability and mobility in patients with persistent low back pain.

PubMed

Helmhout, Pieter H; Witjes, Marloes; Nijhuis-VAN DER Sanden, Ria W; Bron, Carel; van Aalst, Michiel; Staal, J Bart

2017-04-01

It is assumed that low back pain patients who use pain-avoiding immobilizing strategies may benefit from specific back flexion and extension exercises aimed at reducing sagittal lumbar hypomobility. The aim of this study was to test this potential working mechanism in chronic low back pain patients undergoing lumbar extensor strengthening training. A single-group prospective cohort design was used in this study. Patients with persistent low back complaints for at least 2 years were recruited at a specialized physical therapy clinics center. They participated in a progressive 11-week lumbar extensor strength training program, once a week. At baseline, sagittal lumbar mobility in flexion and extension was measured with a computer-assisted inclinometer. Self-rated pain intensity was measured using a visual analogue scale, back-specific functional status was assessed with the Quebec Back Pain Disability Scale and the Patient Specific Complains questionnaire. Statistically significant improvements were found in pain (28% decrease) and functional disability (23% to 36% decrease). Most progress was seen in the first 5 treatment weeks. Lumbar mobility in flexion showed non-significant increases over time (+12%). Pre-post treatment changes in flexion and extension mobility did not contribute significantly to the models. The retained factors together explained 15% to 48% of the variation in outcome. Specific lumbar strengthening showed clinically relevant improvements in pain and disability in patients with persistent chronic low back pain. These improvements did not necessarily relate to improvements in lumbar mobility. Parameters representing other domains of adaptations to exercise may be needed to evaluate the effects of back pain management.

Progressive Changes in Walking Kinematics and Kinetics After Anterior Cruciate Ligament Injury and Reconstruction: A Review and Meta-Analysis.

PubMed

Slater, Lindsay V; Hart, Joseph M; Kelly, Adam R; Kuenze, Christopher M

2017-09-01

  Anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) result in persistent alterations in lower extremity movement patterns. The progression of lower extremity biomechanics from the time of injury has not been described.   To compare the 3-dimensional (3D) lower extremity kinematics and kinetics of walking among individuals with ACL deficiency (ACLD), individuals with ACLR, and healthy control participants from 3 to 64 months after ACLR.   We searched PubMed and Web of Science from 1970 through 2013.   We selected only articles that provided peak kinematic and kinetic values during walking in individuals with ACLD or ACLR and comparison with a healthy control group or the contralateral uninjured limb.   A total of 27 of 511 identified studies were included. Weighted means, pooled standard deviations, and 95% confidence intervals were calculated for the healthy control, ACLD, and ACLR groups at each reported time since surgery. The magnitude of between-groups (ACLR versus ACLD, control, or contralateral limb) differences at each time point was evaluated using Cohen d effect sizes and associated 95% confidence intervals. Peak knee-flexion angle (Cohen d = -0.41) and external knee-extensor moment (Cohen d = -0.68) were smaller in the ACLD than in the healthy control group. Peak knee-flexion angle (Cohen d range = -0.78 to -1.23) and external knee-extensor moment (Cohen d range = -1.39 to -2.16) were smaller in the ACLR group from 10 to 40 months after ACLR. Reductions in external knee-adduction moment (Cohen d range = -0.50 to -1.23) were present from 9 to 42 months after ACLR.   Reductions in peak knee-flexion angle, external knee-flexion moment, and external knee-adduction moment were present in the ACLD and ACLR groups. This movement profile during the loading phase of gait has been linked to knee-cartilage degeneration and may contribute to the development of osteoarthritis after ACLR.

Effects of Inclined Treadmill Walking on Pelvic Anterior Tilt Angle, Hamstring Muscle Length, and Trunk Muscle Endurance of Seated Workers with Flat-back Syndrome.

PubMed

Kim, Min-Hee; Yoo, Won-Gyu

2014-06-01

[Purpose] This study investigated the effects of inclined treadmill walking on pelvic anterior tilt angle, hamstring muscle length, and back muscle endurance of seated workers with flat-back syndrome. [Subjects] Eight seated workers with flat-back syndrome who complained of low-back pain in the L3-5 region participated in this study. [Methods] The subjects performed a walking exercise on a 30° inclined treadmill. We measured the pelvic anterior tilt angle, hamstring muscle length, and back muscle endurance before and after inclined treadmill walking. [Results] Anterior pelvic tilt angle and active knee extension angle significantly increased after inclined treadmill walking. Trunk extensor and flexor muscle endurance times were also significantly increased compared to the baseline. [Conclusion] Inclined treadmill walking may be an effective approach for the prevention or treatment of low-back pain in flat-back syndrome.

The effect of temperature on amount and structure of motor variability during 2-minute maximum voluntary contraction.

PubMed

Brazaitis, Marius; Skurvydas, Albertas; Pukėnas, Kazimieras; Daniuseviciūtė, Laura; Mickevicienė, Dalia; Solianik, Rima

2012-11-01

In this study, we questioned whether local cooling of muscle or heating involving core and muscle temperatures are the main indicators for force variability. Ten volunteers performed a 2-min maximum voluntary contraction (MVC) of the knee extensors under control (CON) conditions after passive heating (HT) and cooling (CL) of the lower body. HT increased muscle and rectal temperatures, whereas CL lowered muscle temperature but did not affect rectal temperature. During 2-min MVC, peak force decreased to a lower level in HT compared with CON and CL experiments. Greater central fatigue was found in the HT experiment, and there was less in the CL experiment than in the CON experiment. Increased core and muscle temperature increased physiological tremor and the amount and structural complexity of force variability of the exercising muscles, whereas local muscle cooling decreased all force variability variables measured. Copyright © 2012 Wiley Periodicals, Inc.

The immediate intervention effects of robotic training in patients after anterior cruciate ligament reconstruction.

PubMed

Hu, Chunying; Huang, Qiuchen; Yu, Lili; Ye, Miao

2016-07-01

[Purpose] The purpose of this study was to examine the immediate effects of robot-assisted therapy on functional activity level after anterior cruciate ligament reconstruction. [Subjects and Methods] Participants included 10 patients (8 males and 2 females) following anterior cruciate ligament reconstruction. The subjects participated in robot-assisted therapy and treadmill exercise on different days. The Timed Up-and-Go test, Functional Reach Test, surface electromyography of the vastus lateralis and vastus medialis, and maximal extensor strength of isokinetic movement of the knee joint were evaluated in both groups before and after the experiment. [Results] The results for the Timed Up-and-Go Test and the 10-Meter Walk Test improved in the robot-assisted rehabilitation group. Surface electromyography of the vastus medialis muscle showed significant increases in maximum and average discharge after the intervention. [Conclusion] The results suggest that walking ability and muscle strength can be improved by robotic training.

Characteristics and preliminary observations of the influence of electromyostimulation on the size and function of human skeletal muscle during 30 days of simulated microgravity

NASA Technical Reports Server (NTRS)

Duvoisin, Marc R.; Convertino, Victor A.; Buchanan, Paul; Gollnick, Philip A.; Dudley, Gary A.

1989-01-01

The effect of transcutaneous electromyostimulation (EMS) on the development of atrophy and the loss of strength in lower limb musculature in humans exposed to microgravity was determined in three subjects who received EMS twice daily in a 3-d on/1-d off cycle on their dominant leg during 30 days of bedrest. The output waveform from the stimulator was sequenced to the knee extensors, knee flexors, ankle extensors, and ankle flexors, and caused three isometric contractions of each muscle group per minute. It was found that, in the dominant leg, EMS acted to attenuate the changes caused by bedrest, such as reductions in the leg volume, muscle compartment size, cross-sectional area of slow- and fast-twitch fibers, strength, and aerobic enzyme activities, and an increase in leg compliance.

Effects of the forearm support band on wrist extensor muscle fatigue.

PubMed

Knebel, P T; Avery, D W; Gebhardt, T L; Koppenhaver, S L; Allison, S C; Bryan, J M; Kelly, A

1999-11-01

A crossover experimental design with repeated measures. To determine whether the forearm support band alters wrist extensor muscle fatigue. Fatigue of the wrist extensor muscles is thought to be a contributing factor in the development of lateral epicondylitis. The forearm support band is purported to reduce or prevent symptoms of lateral epicondylitis but the mechanism of action is unknown. Fifty unimpaired subjects (36 men, 14 women; mean age = 29 +/- 6 years) were tested with and without a forearm support band before and after a fatiguing bout of exercise. Peak wrist extension isometric force, peak isometric grip force, and median power spectral frequency for wrist extensor electromyographic activity were measured before and after exercise and with and without the forearm support band. A 2 x 2 repeated measures multivariate analysis of variance was used to analyze the data, followed by univariate analysis of variance and Tukey's multiple comparison tests. Peak wrist extension isometric force, peak grip isometric force, and median power spectral frequency were all reduced after exercise. However, there was a significant reduction in peak grip isometric force and peak wrist extension isometric force values for the with-forearm support band condition (grip force 28%, wrist extension force 26%) compared to the without-forearm support band condition (grip force 18%, wrist extension force 15%). Wearing the forearm support band increased the rate of fatigue in unimpaired individuals. Our findings do not support the premise that wearing the forearm support band reduces muscle fatigue in the wrist extensors.

Changes in force, surface and motor unit EMG during post-exercise development of low frequency fatigue in vastus lateralis muscle.

PubMed

de Ruiter, C J; Elzinga, M J H; Verdijk, P W L; van Mechelen, W; de Haan, A

2005-08-01

We investigated the effects of low frequency fatigue (LFF) on post-exercise changes in rectified surface EMG (rsEMG) and single motor unit EMG (smuEMG) in vastus lateralis muscle (n = 9). On two experimental days the knee extensors were fatigued with a 60-s-isometric contraction (exercise) at 50% maximal force capacity (MFC). On the first day post-exercise (15 s, 3, 9, 15, 21 and 27 min) rsEMG and electrically-induced (surface stimulation) forces were investigated. SmuEMG was obtained on day two. During short ramp and hold (5 s) contractions at 50% MFC, motor unit discharges of the same units were followed over time. Post-exercise MFC and tetanic force (100 Hz stimulation) recovered to about 90% of the pre-exercise values, but recovery with 20 Hz stimulation was less complete: the 20-100 Hz force ratio (mean +/- SD) decreased from 0.65+/-0.06 (pre-exercise) to 0.56+/-0.04 at 27 min post-exercise (P<0.05), indicative of LFF. At 50% MFC, pre-exercise rsEMG (% pre-exercise maximum) and motor unit discharge rate were 51.1 +/- 12.7% and 14.1 +/- 3.7 (pulses per second; pps) respectively, 15 s post-exercise the respective values were 61.4 +/- 15.4% (P<0.05) and 13.2 +/- 5.6 pps (P>0.05). Thereafter, rsEMG (at 50% MFC) remained stable but motor unit discharge rate significantly increased to 17.7 +/- 3.9 pps 27 min post-exercise. The recruitment threshold decreased (P<0.05) from 27.7 +/- 6.6% MFC before exercise to 25.2 +/- 6.7% 27 min post-exercise. The increase in discharge rate was significantly greater than could be expected from the decrease in recruitment threshold. Thus, post-exercise LFF was compensated by increased motor unit discharge rates which could only partly be accounted for by the small decrease in motor unit recruitment threshold.

Whole-Body Vibration Intensities in Chronic Stroke: A Randomized Controlled Trial.

PubMed

Liao, Lin-Rong; Ng, Gabriel Y F; Jones, Alice Y M; Huang, Mei-Zhen; Pang, Marco Y C

2016-07-01

A single-blinded randomized controlled study was conducted to investigate the effects of different whole-body vibration (WBV) intensities on body functions/structures, activity, and participation in individuals with stroke. Eighty-four individuals with chronic stroke (mean age = 61.2 yr, SD = 9.2) with mild to moderate motor impairment (Chedoke-McMaster Stroke Assessment lower limb motor score: median = 9 out of 14, interquartile range = 7-11.8) were randomly assigned to a low-intensity WBV, high-intensity WBV, or control group. The former two groups performed various leg exercises while receiving low-intensity and high-intensity WBV, respectively. Controls performed the same exercises without WBV. All individuals received 30 training sessions over an average period of 75.5 d (SD = 5.2). Outcome measurements included knee muscle strength (isokinetic dynamometry), knee and ankle joint spasticity (Modified Ashworth Scale), balance (Mini Balance Evaluation Systems Test), mobility (Timed-Up-and-Go test), walking endurance (6-Minute Walk Test), balance self-efficacy (Activities-specific Balance Confidence scale), participation in daily activities (Frenchay Activity Index), perceived environmental barriers to societal participation (Craig Hospital Inventory of Environmental Factors), and quality of life (Short-Form 12 Health Survey). Assessments were performed at baseline and postintervention. Intention-to-treat analysis revealed a significant time effect for muscle strength, Timed-Up-and-Go distance, and oxygen consumption rate achieved during the 6-Minute Walk Test, the Mini Balance Evaluation Systems Test, the Activities-specific Balance Confidence scale, and the Short-Form 12 Health Survey physical composite score domain (P < 0.05). However, the time-group interaction was not significant for any of the outcome measures (P > 0.05). The addition of the 30-session WBV paradigm to the leg exercise protocol was no more effective in enhancing body functions/structures, activity, and participation than leg exercises alone in chronic stroke patients with mild to moderate motor impairments.

Effect of Home Exercise Program in Patients With Knee Osteoarthritis: A Systematic Review and Meta-analysis.

PubMed

Anwer, Shahnawaz; Alghadir, Ahmad; Brismée, Jean-Michel

2016-01-01

The Osteoarthritis Research Society International recommended that nonpharmacological methods include patient education programs, weight reduction, coping strategies, and exercise programs for the management of knee osteoarthritis (OA). However, neither a systematic review nor a meta-analysis has been published regarding the effectiveness of home exercise programs for the management of knee OA. The purpose of this systematic review was to examine the evidence regarding the effect of home exercise programs with and without supervised clinic-based exercises in the management of knee OA. We searched PubMed, CINAHL, Embase, Scopus, and PEDro for research articles published prior to September 2014 using key words such as pain, exercise, home exercise program, rehabilitation, supervised exercise program, and physiotherapy in combination with Medical Subject Headings "Osteoarthritis knee." We selected randomized and case-controlled trials published in English language. To verify the quality of the selected studies, we applied the PEDro Scale. Two evaluators individually selected the studies based on titles, excluding those articles that were not related to the objectives of this review. One evaluator extracted data from the included studies. A second evaluator independently verified extracted data for accuracy. A total of 31 studies were found in the search. Of these, 19 studies met the inclusion criteria and were further analyzed. Seventeen of these 19 studies reached high methodological quality on the PEDro scale. Although the methods and home exercise program interventions varied widely in these studies, most found significant improvements in pain and function in individuals with knee OA. The analysis indicated that both home exercise programs with and without supervised clinic-based exercises were beneficial in the management of knee OA. The large evidence of high-quality trials supports the effectiveness of home exercise programs with and without supervised clinic-based exercises in the rehabilitation of knee OA. In addition, small but growing evidence supports the effectiveness of other types of exercise such as tai chi, balance, and proprioceptive training for individuals with knee OA.

Functional and Neuromuscular Changes in the Hamstrings After Drop Jumps and Leg Curls

PubMed Central

Sarabon, Nejc; Panjan, Andrej; Rosker, Jernej; Fonda, Borut

2013-01-01

The purpose of this study was to use a holistic approach to investigate changes in jumping performance, kinaesthesia, static balance, isometric strength and fast stepping on spot during a 5-day recovery period, following an acute bout of damaging exercise consisted of drop jumps and leg curls, where specific emphasis was given on the hamstring muscles. Eleven young healthy subjects completed a series of highly intensive damaging exercises for their hamstring muscles. Prior to the exercise, and during the 5-day recovery period, the subjects were tested for biochemical markers (creatine kinase, aspartate aminotransferase, and lactate dehydrogenase), perceived pain sensation, physical performance (squat jump, counter movement jump, maximal frequency leg stamping, maximal isometric torque production and maximally explosive isometric torque production), kinaesthesia (active torque tracking) and static balance. We observed significant decreases in maximal isometric knee flexion torque production, the rate of torque production, and majority of the parameters for vertical jump performance. No alterations were found in kinaesthesia, static balance and fast stepping on spot. The highest drop in performance and increase in perceived pain sensation generally occurred 24 or 48 hours after the exercise. Damaging exercise substantially alters the neuromuscular functions of the hamstring muscles, which is specifically relevant for sports and rehabilitation experts, as the hamstrings are often stretched to significant lengths, in particular when the knee is extended and hip flexed. These findings are practically important for recovery after high-intensity trainings for hamstring muscles. Key Points Hamstring function is significantly reduced following specifically damaging exercise. It fully recovers 120 hours after the exercise. Prevention of exercise-induced muscle damage is cruicial for maintaining normal training regime. PMID:24149148

Lower extremity joint kinetics and energetics during backward running.

PubMed

DeVita, P; Stribling, J

1991-05-01

The purpose of this study was to measure lower extremity joint moments of force and joint muscle powers used to perform backward running. Ten trials of high speed (100 Hz) sagittal plane film records and ground reaction force data (1000 Hz) describing backward running were obtained from each of five male runners. Fifteen trials of forward running data were obtained from one of these subjects. Inverse dynamics were performed on these data to obtain the joint moments and powers, which were normalized to body mass to make between-subject comparisons. Backward running hip moment and power patterns were similar in magnitude and opposite in direction to forward running curves and produced more positive work in stance. Functional roles of knee and ankle muscles were interchanged between backward and forward running. Knee extensors were the primary source of propulsion in backward running owing to greater moment and power output (peak moment = 3.60 N.m.kg-1; peak power = 12.40 W.kg-1) compared with the ankle (peak moment = 1.92 N.m.kg-1; peak power = 7.05 W.kg-1). The ankle plantarflexors were the primary shock absorbers, producing the greatest negative power (peak = -6.77 W.kg-1) during early stance. Forward running had greater ankle moment and power output for propulsion and greater knee negative power for impact attenuation. The large knee moment in backward running supported previous findings indicating that backward running training leads to increased knee extensor torque capabilities.

Runners with Patellofemoral Pain Exhibit Greater Peak Patella Cartilage Stress Compared to Pain-Free Runners.

PubMed

Liao, Tzu-Chieh; Keyak, Joyce H; Powers, Christopher M

2018-02-27

The purpose of this study is to determine whether recreational runners with patellofemoral pain (PFP) exhibit greater peak patella cartilage stress compared to pain-free runners. A secondary purpose was to determine the kinematic and/or kinetic predictors of peak patella cartilage stress during running. Twenty-two female recreational runners participated (12 with PFP and 10 pain-free controls). Patella cartilage stress profiles were quantified using subject-specific finite element models simulating the maximum knee flexion angle during stance phase of running. Input parameters to the finite element model included subject-specific patellofemoral joint geometry, quadriceps muscle forces, and lower extremity kinematics in the frontal and transverse planes. Tibiofemoral joint kinematics and kinetics were quantified to determine the best predictor of stress using stepwise regression analysis. Compared to the pain-free runners, those with PFP exhibited greater peak hydrostatic pressure (PFP vs. control, 21.2 ± 5.6 MPa vs. 16.5 ± 4.6 MPa) and maximum shear stress (11.3 ± 4.6 MPa vs. 8.7 ± 2.3 MPa). Knee external rotation was the best predictor of peak hydrostatic pressure and peak maximum shear stress (38% and 25% of variances, respectively) followed by the knee extensor moment (21% and 25% of variances, respectively). Runners with PFP exhibit greater peak patella cartilage stress during running compared to pain-free individuals. The combination of knee external rotation and a high knee extensor moment best predicted elevated peak stress during running.

High-threshold motor unit firing reflects force recovery following a bout of damaging eccentric exercise.

PubMed

Macgregor, Lewis J; Hunter, Angus M

2018-01-01

Exercise-induced muscle damage (EIMD) is associated with impaired muscle function and reduced neuromuscular recruitment. However, motor unit firing behaviour throughout the recovery period is unclear. EIMD impairment of maximal voluntary force (MVC) will, in part, be caused by reduced high-threshold motor unit firing, which will subsequently increase to recover MVC. Fourteen healthy active males completed a bout of eccentric exercise on the knee extensors, with measurements of MVC, rate of torque development and surface electromyography performed pre-exercise and 2, 3, 7 and 14 days post-exercise, on both damaged and control limb. EIMD was associated with decreased MVC (235.2 ± 49.3 Nm vs. 161.3 ± 52.5 Nm; p <0.001) and rate of torque development (495.7 ± 136.9 Nm.s-1 vs. 163.4 ± 163.7 Nm.s-1; p <0.001) 48h post-exercise. Mean motor unit firing rate was reduced (16.4 ± 2.2 Hz vs. 12.6 ± 1.7 Hz; p <0.01) in high-threshold motor units only, 48h post-exercise, and common drive was elevated (0.36 ± 0.027 vs. 0.56 ± 0.032; p< 0.001) 48h post-exercise. The firing rate of high-threshold motor units was reduced in parallel with impaired muscle function, whilst early recruited motor units remained unaltered. Common drive of motor units increased in offset to the firing rate impairment. These alterations correlated with the recovery of force decrement, but not of pain elevation. This study provides fresh insight into the central mechanisms associated with EIMD recovery, relative to muscle function. These findings may in turn lead to development of novel management and preventative procedures.

High-threshold motor unit firing reflects force recovery following a bout of damaging eccentric exercise

PubMed Central

Macgregor, Lewis J.

2018-01-01

Exercise-induced muscle damage (EIMD) is associated with impaired muscle function and reduced neuromuscular recruitment. However, motor unit firing behaviour throughout the recovery period is unclear. EIMD impairment of maximal voluntary force (MVC) will, in part, be caused by reduced high-threshold motor unit firing, which will subsequently increase to recover MVC. Fourteen healthy active males completed a bout of eccentric exercise on the knee extensors, with measurements of MVC, rate of torque development and surface electromyography performed pre-exercise and 2, 3, 7 and 14 days post-exercise, on both damaged and control limb. EIMD was associated with decreased MVC (235.2 ± 49.3 Nm vs. 161.3 ± 52.5 Nm; p <0.001) and rate of torque development (495.7 ± 136.9 Nm.s-1 vs. 163.4 ± 163.7 Nm.s-1; p <0.001) 48h post-exercise. Mean motor unit firing rate was reduced (16.4 ± 2.2 Hz vs. 12.6 ± 1.7 Hz; p <0.01) in high-threshold motor units only, 48h post-exercise, and common drive was elevated (0.36 ± 0.027 vs. 0.56 ± 0.032; p< 0.001) 48h post-exercise. The firing rate of high-threshold motor units was reduced in parallel with impaired muscle function, whilst early recruited motor units remained unaltered. Common drive of motor units increased in offset to the firing rate impairment. These alterations correlated with the recovery of force decrement, but not of pain elevation. This study provides fresh insight into the central mechanisms associated with EIMD recovery, relative to muscle function. These findings may in turn lead to development of novel management and preventative procedures. PMID:29630622

An acute bout of localized resistance exercise can rapidly improve inhibitory control

PubMed Central

Tsukamoto, Hayato; Suga, Tadashi; Takenaka, Saki; Takeuchi, Tatsuya; Tanaka, Daichi; Hamaoka, Takafumi; Hashimoto, Takeshi; Isaka, Tadao

2017-01-01

The positive effect of acute resistance exercise on executive function, such as inhibitory control (IC), is poorly understood. Several previous studies have demonstrated this effect using whole-body resistance exercise. However, it remains unclear whether localized resistance exercise performed using only limited muscle groups could also acutely improve IC. Thus, the present study examined the effect of an acute bout of localized resistance exercise on IC. Twelve healthy men performed a color-word Stroop task (CWST) before and immediately after the experimental conditions, which consisted of 2 resistance exercises and a resting control (CON). Bilateral knee extension was used to create 2 resistance exercise conditions: light-intensity resistance exercise (LRE) and high-intensity resistance exercise (HRE) conditions, which were 40% and 80% of one-repetition maximum, respectively. The resistance exercise session was programmed for 6 sets with 10 repetitions per set. The CWST-measured IC was significantly improved immediately after both LRE and HRE, but it did not improve immediately after CON. However, the improved IC was significantly greater in HRE than in LRE. The present findings showed that IC could be rapidly improved by an acute bout of localized resistance exercise, especially with high-intensity. Therefore, we suggest that in addition to whole-body resistance exercise, localized resistance exercise performed using limited muscle groups may be sufficient for improving IC. PMID:28877232

Myostatin dysfunction impairs force generation in extensor digitorum longus muscle and increases exercise-induced protein efflux from extensor digitorum longus and soleus muscles.

PubMed

Baltusnikas, Juozas; Kilikevicius, Audrius; Venckunas, Tomas; Fokin, Andrej; Bünger, Lutz; Lionikas, Arimantas; Ratkevicius, Aivaras

2015-08-01

Myostatin dysfunction promotes muscle hypertrophy, which can complicate assessment of muscle properties. We examined force generating capacity and creatine kinase (CK) efflux from skeletal muscles of young mice before they reach adult body and muscle size. Isolated soleus (SOL) and extensor digitorum longus (EDL) muscles of Berlin high (BEH) mice with dysfunctional myostatin, i.e., homozygous for inactivating myostatin mutation, and with a wild-type myostatin (BEH+/+) were studied. The muscles of BEH mice showed faster (P < 0.01) twitch and tetanus contraction times compared with BEH+/+ mice, but only EDL displayed lower (P < 0.05) specific force. SOL and EDL of age-matched but not younger BEH mice showed greater exercise-induced CK efflux compared with BEH+/+ mice. In summary, myostatin dysfunction leads to impairment in muscle force generating capacity in EDL and increases susceptibility of SOL and EDL to protein loss after exercise.

Physical exercise: does it help in relieving pain and increasing mobility among older adults with chronic pain?

PubMed

Tse, Mimi M Y; Wan, Vanessa T C; Ho, Suki S K

2011-03-01

To provide a physical exercise programme for older adults living in nursing homes. Pain is common among older persons and for those already in long-term care and having difficulty in coping with pain will be at risk of further reducing their optimal independent function. A quasi-experimental single group pretest-posttest design. Older persons from a nursing home were invited to join an eight-week physical exercise programme. Each session lasted an hour and sessions were conducted once a week by physiotherapist and nurses. Physical exercise programme consisted of stretching, strengthening, balancing, towel dancing and self-administered massage to various acupressure points. On completion of each session, older persons were given a pamphlet with pictures to illustrate the exercise of the day and they were encouraged to practise these exercises by themselves. Outcome measures including pain intensity, range of movement, activities of daily living and mobility were collected before and after the physical exercise programme. There were 75 older adult participants (57 female and 18 male, mean age 85.14 SD 5.30). Seventy-three percent (n = 55) of them had pain in the previous three months and were referred as pain group, while 25% (n = 20) were no pain group. Pain scores of 4.89 (on a 10-point scale) indicated medium pain intensity before the intervention for the pain group; the location of pain was mainly in the knee, back and shoulder. On completion of the physical exercise programme, there was a significant decrease in pain intensity to 2.89 (SD 2.14) (p < 0.01). There was a significant increase in range of movement in the neck, shoulder, back, hip and knee rotation, flex and abduction (p < 0.01). Mobility level was significantly increased post intervention, yet activities of daily living remained unchanged. The present study demonstrated the effectiveness of a physical exercise programme in relieving pain and enhancing functional mobility for older persons. Relevance to clinical practice.  It is important to educate older persons, especially those living in nursing homes, on the importance of engaging in regular physical exercise and maintaining mobility. © 2011 Blackwell Publishing Ltd.

Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI).

PubMed

Bochkezanian, Vanesa; Newton, Robert U; Trajano, Gabriel S; Vieira, Amilton; Pulverenti, Timothy S; Blazevich, Anthony J

2018-02-13

Neuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI. Nine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 μs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable. Total knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (- 31.3 ± 25.7%). However, there were no statistically significant differences between these sub-groups or between conditions when the data were pooled. Based on the present results there is insufficient evidence to conclude that patellar tendon vibration provides a clear benefit to muscle force production or delays muscle fatigue during wide-pulse width, moderate-intensity NMES in people with SCI. ACTRN12618000022268 . Date: 11/01/2018. Retrospectively registered.

Reliability of the hand held dynamometer in measuring muscle strength in people with interstitial lung disease.

PubMed

Dowman, Leona; McDonald, Christine F; Hill, Catherine J; Lee, Annemarie; Barker, Kathryn; Boote, Claire; Glaspole, Ian; Goh, Nicole; Southcott, Annemarie; Burge, Angela; Ndongo, Rebecca; Martin, Alicia; Holland, Anne E

2016-09-01

To evaluate the inter-rater and intra-rater reliability of the hand held dynamometer in measuring muscle strength in people with interstitial lung disease (ILD). Test retest reliability of hand-held dynamometry for elbow flexor and knee extensor strength between two independent raters and two testing sessions. Physiotherapy department within a tertiary hospital. Thirty participants with ILD of varying aetiology were included. Twenty participants completed the inter-rater reliability protocol (10 idiopathic pulmonary fibrosis, mean (SD) age 73 (10) years, 11 male) and 21 participants completed the intra-rater reliability protocol (10 idiopathic pulmonary fibrosis, mean age 71 (10) years, 11 male). Mean muscle strength (kg). Agreement between the two raters and testing sessions was analyzed using Bland-Altman plots and reliability was estimated using intraclass correlation coefficients (ICC). For elbow flexor strength there was a mean difference between raters of -0.6kg (limits of agreement (LOA) -5.6 to 4.4kg) and within raters of -0.3kg (LOA -2.8 to 2.3kg). The ICCs were 0.95 and 0.98, respectively. For knee extensor strength there was a mean difference between raters of -1.5kg (LOA -6.9 to 3.9kg) and within raters of -0.7kg (LOA -3.9 to 2.4kg). The ICCs were 0.95 and 0.97, respectively. Hand-held dynamometry is reliable in measuring elbow flexor and knee extensor strength in people with ILD. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

The comparison of muscle strength and short-term endurance in the different periods of type 2 diabetes

PubMed Central

2014-01-01

Background Patients with type 2 diabetes (T2DM) are subjected to reduction in the quality and oxidative capacity of muscles. The effect of duration of diabetes on the muscle endurance response is not clear and strength as well. Objective The aim of this study was the assessment of strength and endurance of knee extensor and flexor in the patients with T2DM < 10 and T2DM > 10 years in comparison with age, sex, BMI, ABI and PAI-matched health control subjects. Methods Isometric maximal peak torque (MPT) of knee extensor and flexor before and after 40 isokinetic repetitions with velocity of 150 degree/s were recorded in 18 patients with T2DM < 10 Y , 12 patients with T2DM > 10 Y and 20 matched health control (HC) groups. Results Both diabetic patient groups had significant lower isometric and isotonic knee extensor and flexor strength than HC. The endurance indices indicated that whereas the isometric MPT of flexor movement was reduced after isokinetic protocol in the both patient groups in comparison with HC, the less decline was seen in the isotonic torque and work during isokinetic protocol in the T2DM > 10 Y group in comparison with two other groups. The HbA1c and FPG were significantly correlated with strength not with endurance indices. Conclusions It seems the progression of diabetes accompanied with vascular, neural and muscular deficits activate, some adaptive and compensatory processes which can maintain muscle performance. PMID:24476108

RELIABILITY AND VALIDITY OF A MODIFIED ISOMETRIC DYNAMOMETER IN THE ASSESSMENT OF MUSCULAR PERFORMANCE IN INDIVIDUALS WITH ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

PubMed Central

de Vasconcelos, Rodrigo Antunes; Bevilaqua-Grossi, Débora; Shimano, Antonio Carlos; Paccola, Cleber Jansen; Salvini, Tânia Fátima; Prado, Christiane Lanatovits; Junior, Wilson A. Mello

2015-01-01

Objectives: The aim of this study was to evaluate the reliability and validity of a modified isometric dynamometer (MID) in performance deficits of the knee extensor and flexor muscles in normal individuals and in those with ACL reconstructions. Methods: Sixty male subjects were invited to participate of the study, being divided into three groups with 20 subjects each: control group (GC), group of individuals with ACL reconstruction with patellar tendon graft (GTP, and group of individuals with ACL reconstruction with hamstrings graft (GTF). All individuals performed isometric tests in the MID, muscular strength deficits collected were subsequently compared to the tests performed on the Biodex System 3 operating in the isometric and isokinetic mode at speeds of 60°/s and 180o/s. Intraclass ICC correlation calculations were done in order to assess MID reliability, specificity, sensitivity and Kappa's consistency coefficient calculations, respectively, for assessing the MID's validity in detecting muscular deficits and intra- and intergroup comparisons when performing the four strength tests using the ANOVA method. Results: The modified isometric dynamometer (MID) showed excellent reliability and good validity in the assessment of the performance of the knee extensor and flexor muscles groups. In the comparison between groups, the GTP showed significantly greater deficits as compared to the GTF and GC groups. Conclusion: Isometric dynamometers connected to mechanotherapy equipments could be an alternative option to collect data concerning performance deficits of the extensor and flexor muscles groups of the knee in subjects with ACL reconstruction. PMID:27004175

Contralateral structural femoral autograft use in treatment of an open periarticular knee fracture to perform knee arthrodesis.

PubMed

Mack, Andrew W; Helgeson, Melvin D; Tis, John E

2008-09-01

Combat-related blast injuries often cause devastating extremity trauma. We report a case of a 21-year-old male service member who sustained massive bilateral lower extremity trauma secondary to a blast injury. His orthopaedic injuries included a near traumatic disarticulation of the right knee and a left open type IIIB periarticular knee fracture with traumatic patellectomy, loss of the extensor mechanism, and segmental loss of the distal 11 cm of his femur. Definitive treatment of his injuries included a contralateral structural cortical femoral autograft which was implanted into the left knee segmental defect to facilitate knee fusion with an intramedullary knee fusion nail and a right transfemoral amputation. Radiographic evidence of solid fusion was obtained 8 months postoperatively. Currently, the patient is a community ambulator with the aid of his right lower extremity prosthetic limb and cane.

Knee joint stabilization therapy in patients with osteoarthritis of the knee: a randomized, controlled trial.

PubMed

Knoop, J; Dekker, J; van der Leeden, M; van der Esch, M; Thorstensson, C A; Gerritsen, M; Voorneman, R E; Peter, W F; de Rooij, M; Romviel, S; Lems, W F; Roorda, L D; Steultjens, M P M

2013-08-01

To investigate whether an exercise program, initially focusing on knee stabilization and subsequently on muscle strength and performance of daily activities is more effective than an exercise program focusing on muscle strength and performance of daily activities only, in reducing activity limitations in patients with knee osteoarthritis (OA) and instability of the knee joint. A single-blind, randomized, controlled trial involving 159 knee OA patients with self-reported and/or biomechanically assessed knee instability, randomly assigned to two treatment groups. Both groups received a supervised exercise program for 12 weeks, consisting of muscle strengthening exercises and training of daily activities, but only in the experimental group specific knee joint stabilization training was provided. Outcome measures included activity limitations (Western Ontario and McMaster Universities Osteoarthritis Index - WOMAC physical function, primary outcome), pain, global perceived effect and knee stability. Both treatment groups demonstrated large (∼20-40%) and clinically relevant reductions in activity limitations, pain and knee instability, which were sustained 6 months post-treatment. No differences in effectiveness between experimental and control treatment were found on WOMAC physical function (B (95% confidence interval - CI) = -0.01 (-2.58 to 2.57)) or secondary outcome measures, except for a higher global perceived effect in the experimental group (P = 0.04). Both exercise programs were highly effective in reducing activity limitations and pain and restoring knee stability in knee OA patients with instability of the knee. In knee OA patients suffering from knee instability, specific knee joint stabilization training, in addition to muscle strengthening and functional exercises, does not seem to have any additional value. Dutch Trial Register (NTR) registration number: NTR1475. Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

The trivector approach for minimally invasive total knee arthroplasty: a technical note.

PubMed

Benazzo, Francesco; Rossi, Stefano Marco Paolo

2012-09-01

One of the main criticisms of minimally invasive approaches in total knee arthroplasty has been their poor adaptability in cases of major deformity or stiffness of the knee joint. When they are used in such cases, excessive soft-tissue tension is needed to provide appropriate joint exposure. Here, we describe the "mini trivector approach," which has become our standard approach for total knee replacement because it permits us to enlarge the indication for minimally or less invasive total knee replacement to many knees where quad sparing, a subvastus approach, or a mini quad or mini midvastus snip may not be sufficient to achieve correct exposure. It consists of a limited double snip of the VMO and the quadriceps tendon that reduces tension on the extensor mechanism and allows easier verticalization of the patella as well as good joint exposure.

Serratus Anterior and Lower Trapezius Muscle Activities During Multi-Joint Isotonic Scapular Exercises and Isometric Contractions.

PubMed

Tsuruike, Masaaki; Ellenbecker, Todd

2014-11-14

Context :  Proper scapular function during humeral elevation, such as upward rotation, external rotation, and posterior tilting of the scapula, is necessary to prevent shoulder injury. However, the appropriate intensity of rehabilitation exercise for the periscapular muscles has yet to be clarified. Objective :  To identify the serratus anterior, lower trapezius, infraspinatus, and posterior deltoid muscle activities during 2 free-motion exercises using 3 intensities and to compare these muscle activities with isometric contractions during quadruped shoulder flexion and external rotation and abduction of the glenohumeral joint. Design :  Cross-sectional study. Setting :  Health Science Laboratory. Patients or Other Participants :  A total of 16 uninjured, healthy, active, male college students (age = 19.5 ± 1.2 years, height = 173.1 ± 6.5 cm, weight = 68.8 ± 6.6 kg). Main Outcome Measure(s) :  Mean electromyographic activity normalized by the maximal voluntary isometric contraction was analyzed across 3 intensities and 5 exercises. Intraclass correlation coefficients were calculated for electromyographic activity of the 4 muscles in each free-motion exercise. Results :  Significant interactions in electromyographic activity were observed between intensities and exercises (P < .05). The quadruped shoulder-flexion exercise activated all 4 muscles compared with other exercises. Also, the modified robbery free-motion exercise activated the serratus anterior, lower trapezius, and infraspinatus compared with the lawn-mower free-motion exercise. However, neither exercise showed a difference in posterior deltoid electromyographic activity. Conclusions :  Three intensities exposed the nature of the periscapular muscle activities across the different exercises. The free-motion exercise in periscapular muscle rehabilitation may not modify serratus anterior, lower trapezius, and infraspinatus muscle activities unless knee-joint extension is limited.

Serratus Anterior and Lower Trapezius Muscle Activities During Multi-Joint Isotonic Scapular Exercises and Isometric Contractions

PubMed Central

Tsuruike, Masaaki; Ellenbecker, Todd S.

2015-01-01

Context: Proper scapular function during humeral elevation, such as upward rotation, external rotation, and posterior tilting of the scapula, is necessary to prevent shoulder injury. However, the appropriate intensity of rehabilitation exercise for the periscapular muscles has yet to be clarified. Objective: To identify the serratus anterior, lower trapezius, infraspinatus, and posterior deltoid muscle activities during 2 free-motion exercises using 3 intensities and to compare these muscle activities with isometric contractions during quadruped shoulder flexion and external rotation and abduction of the glenohumeral joint. Design: Cross-sectional study. Setting: Health Science Laboratory. Patients or Other Participants: A total of 16 uninjured, healthy, active, male college students (age = 19.5 ± 1.2 years, height = 173.1 ± 6.5 cm, weight = 68.8 ± 6.6 kg). Main Outcome Measure(s): Mean electromyographic activity normalized by the maximal voluntary isometric contraction was analyzed across 3 intensities and 5 exercises. Intraclass correlation coefficients were calculated for electromyographic activity of the 4 muscles in each free-motion exercise. Results: Significant interactions in electromyographic activity were observed between intensities and exercises (P < .05). The quadruped shoulder-flexion exercise activated all 4 muscles compared with other exercises. Also, the modified robbery free-motion exercise activated the serratus anterior, lower trapezius, and infraspinatus compared with the lawn-mower free-motion exercise. However, neither exercise showed a difference in posterior deltoid electromyographic activity. Conclusions: Three intensities exposed the nature of the periscapular muscle activities across the different exercises. The free-motion exercise in periscapular muscle rehabilitation may not modify serratus anterior, lower trapezius, and infraspinatus muscle activities unless knee-joint extension is limited. PMID:25689561

Neuromuscular versus quadriceps strengthening exercise in patients with medial knee osteoarthritis and varus malalignment: a randomized controlled trial.

PubMed

Bennell, Kim L; Kyriakides, Mary; Metcalf, Ben; Egerton, Thorlene; Wrigley, Tim V; Hodges, Paul W; Hunt, Michael A; Roos, Ewa M; Forbes, Andrew; Ageberg, Eva; Hinman, Rana S

2014-04-01

To compare the effects of neuromuscular exercise (NEXA) and quadriceps strengthening (QS) on the knee adduction moment (an indicator of mediolateral distribution of knee load), pain, and physical function in patients with medial knee joint osteoarthritis (OA) and varus malalignment. One hundred patients with medial knee pain, mostly moderate-to-severe radiographic medial knee OA, and varus malalignment were randomly allocated to one of two 12-week exercise programs. Each program involved 14 individually supervised exercise sessions with a physiotherapist plus a home exercise component. Primary outcomes were peak external knee adduction moment (3-dimensional gait analysis), pain (visual analog scale), and self-reported physical function (Western Ontario and McMaster Universities Osteoarthritis Index). Eighty-two patients (38 [76%] of 50 in the NEXA group and 44 [88%] of 50 in the QS group) completed the trial. There was no significant between-group difference in the change in the peak knee adduction moment (mean difference 0.13 Nm/[body weight × height]% [95% confidence interval (95% CI) -0.08, 0.33]), pain (mean difference 2.4 mm [95% CI -6.0, 10.8]), or physical function (mean difference -0.8 units [95% CI -4.0, 2.4]). Neither group showed a change in knee moments following exercise, whereas both groups showed similar significant reductions in pain and improvement in physical function. Although comparable improvements in clinical outcomes were observed with both neuromuscular and quadriceps strengthening exercise in patients with moderate varus malalignment and mostly moderate-to-severe medial knee OA, these forms of exercise did not affect the knee adduction moment, a key predictor of structural disease progression. Copyright © 2014 by the American College of Rheumatology.

Effects of neuromuscular training (NEMEX-TJR) on patient-reported outcomes and physical function in severe primary hip or knee osteoarthritis: a controlled before-and-after study.

PubMed

Ageberg, Eva; Nilsdotter, Anna; Kosek, Eva; Roos, Ewa M

2013-08-08

The benefits of exercise in mild and moderate knee or hip osteoarthritis (OA) are apparent, but the evidence in severe OA is less clear. We recently reported that neuromuscular training was well tolerated and feasible in patients with severe primary hip or knee OA. The aims of this controlled before-and-after study were to compare baseline status to an age-matched population-based reference group and to examine the effects of neuromuscular training on patient-reported outcomes and physical function in patients with severe primary OA of the hip or knee. 87 patients (60-77 years) with severe primary OA of the hip (n = 38, 55% women) or knee (n = 49, 59% women) awaiting total joint replacement (TJR) had supervised, neuromuscular training (NEMEX-TJR) in groups with individualized level and progression of training. A reference group (n = 43, 53% women) was included for comparison with patients' data. Assessments included self-reported outcomes (HOOS/KOOS) and measures of physical function (chair stands, number of knee bends/30 sec, knee extensor strength, 20-meter walk test) at baseline and at follow-up before TJR. Analysis of covariance (ANCOVA) was used for comparing patients and references and elucidating influence of demographic factors on change. The paired t-test was used for comparisons within groups. At baseline, patients reported worse scores than the references in all HOOS/KOOS subscales (hip 27-47%, knee 14-52%, of reference scores, respectively) and had functional limitations (hip 72-85%, knee 42-85%, of references scores, respectively). NEMEX-TJR (mean 12 weeks (SD 5.6) of training) improved self-reported outcomes (hip 9-29%, knee 7-20%) and physical function (hip 3-18%, knee 5-19%) (p < 0.005). Between 42% and 62% of hip OA patients, and 39% and 61% of knee OA patients, displayed a clinically meaningful improvement (≥15%) in HOOS/KOOS subscales by training. The improvement in HOOS/KOOS subscale ADL was greater for patients with knee OA than hip OA, while the improvement in subscale Sport/Rec was greater for patients with hip OA than knee OA. Both self-reported outcomes and physical function were clearly worse compared with the reference group. Neuromuscular training with an individualized approach and gradual progression showed promise for improving patient-reported outcomes and physical function even in older patients with severe primary OA of the hip or knee.

Assessing the therapeutic effect of 625-nm light-emitting diodes

NASA Astrophysics Data System (ADS)

Mao, Zongzhen; Xu, Guodong; Yang, Yi

2014-09-01

To evaluate the effects of red Light-Emitting Diodes on elbow extensor and flexor strength and the recovery of exercise induced fatigue, the torque values from the isokinetic dynamometer as well as biochemistry parameters were used as outcome measures. A randomized double-blind placebo-controlled crossover trial was performed with twenty male young tennis athletes. Active LED therapy (LEDT, with wavelength 625nm, 10 minutes total irradiation time, irradiated area amount to 30cm2, and 900J of total energy irradiated) or an identical placebo was delivered under double-blinded conditions to the left elbow just before exercise. The isokinetic muscle strength was measured immediately after irradiation. The blood lactate levels were sampled pre-exercise and post-exercise. The peak torque values of elbow extensor strength were significantly different between two groups. As in elbow flexor strength, the difference of peak torque was not significant. The blood lactate concentration of LEDT group post-exercise was significantly lower than those of placebo group. The results indicate that 625nm LED therapy is effective in preventing muscle fatigue as it can significantly reduce peak torque value of elbow extensors and blood lactate concentration. It has no effect on the strength of left elbow flexor or backhand performance in tennis.

A Randomized Trial on the Effect of Bone Tissue on Vibration-induced Muscle Strength Gain and Vibration-induced Reflex Muscle Activity

PubMed Central

Cidem, Muharrem; Karacan, İlhan; Diraçoğlu, Demirhan; Yıldız, Aysel; Küçük, Suat Hayri; Uludağ, Murat; Gün, Kerem; Özkaya, Murat; Karamehmetoğlu, Şafak Sahir

2014-01-01

Background: Whole-body vibration (WBV) induces reflex muscle activity and leads to increased muscle strength. However, little is known about the physiological mechanisms underlying the effects of whole-body vibration on muscular performance. Tonic vibration reflex is the most commonly cited mechanism to explain the effects of whole-body vibration on muscular performance, although there is no conclusive evidence that tonic vibration reflex occurs. The bone myoregulation reflex is another neurological mechanism used to explain the effects of vibration on muscular performance. Bone myoregulation reflex is defined as a reflex mechanism in which osteocytes exposed to cyclic mechanical loading induce muscle activity. Aims: The aim of this study was to assess whether bone tissue affected vibration-induced reflex muscle activity and vibration-induced muscle strength gain. Study Design: A prospective, randomised, controlled, double-blind, parallel-group clinical trial. Methods: Thirty-four participants were randomised into two groups. High-magnitude whole-body vibration was applied in the exercise group, whereas low-magnitude whole-body vibration exercises were applied in the control group throughout 20 sessions. Hip bone mineral density, isokinetic muscle strength, and plasma sclerostin levels were measured. The surface electromyography data were processed to obtain the Root Mean Squares, which were normalised by maximal voluntarily contraction. Results: In the exercise group, muscle strength increased in the right and left knee flexors (23.9%, p=0.004 and 27.5%, p<0.0001, respectively). However, no significant change was observed in the knee extensor muscle strength. There was no significant change in the knee muscle strength in the control group. The vibration-induced corrected Root Mean Squares of the semitendinosus muscle was decreased by 2.8 times (p=0.005) in the exercise group, whereas there was no change in the control group. Sclerostin index was decreased by 15.2% (p=0.031) in the exercise group and increased by 20.8% (p=0.028) in the control group. A change in the sclerostin index was an important predictor of a change in the vibration-induced normalised Root Mean Square of the semitendinosus muscle (R2=0.7, p=0.0001). Femoral neck bone mineral density was an important predictor of muscle strength gain (R2=0.26, p=0.035). Conclusion: This study indicates that bone tissue may have an effect on vibration-induced muscle strength gain and vibration-induced reflex muscle activity. Trial registration: ClinicalTrials.gov: NCT01310348. PMID:25207162

A Randomized Trial on the Effect of Bone Tissue on Vibration-induced Muscle Strength Gain and Vibration-induced Reflex Muscle Activity.

PubMed

Cidem, Muharrem; Karacan, Ilhan; Diraçoğlu, Demirhan; Yıldız, Aysel; Küçük, Suat Hayri; Uludağ, Murat; Gün, Kerem; Ozkaya, Murat; Karamehmetoğlu, Safak Sahir

2014-03-01

Whole-body vibration (WBV) induces reflex muscle activity and leads to increased muscle strength. However, little is known about the physiological mechanisms underlying the effects of whole-body vibration on muscular performance. Tonic vibration reflex is the most commonly cited mechanism to explain the effects of whole-body vibration on muscular performance, although there is no conclusive evidence that tonic vibration reflex occurs. The bone myoregulation reflex is another neurological mechanism used to explain the effects of vibration on muscular performance. Bone myoregulation reflex is defined as a reflex mechanism in which osteocytes exposed to cyclic mechanical loading induce muscle activity. The aim of this study was to assess whether bone tissue affected vibration-induced reflex muscle activity and vibration-induced muscle strength gain. A prospective, randomised, controlled, double-blind, parallel-group clinical trial. Thirty-four participants were randomised into two groups. High-magnitude whole-body vibration was applied in the exercise group, whereas low-magnitude whole-body vibration exercises were applied in the control group throughout 20 sessions. Hip bone mineral density, isokinetic muscle strength, and plasma sclerostin levels were measured. The surface electromyography data were processed to obtain the Root Mean Squares, which were normalised by maximal voluntarily contraction. In the exercise group, muscle strength increased in the right and left knee flexors (23.9%, p=0.004 and 27.5%, p<0.0001, respectively). However, no significant change was observed in the knee extensor muscle strength. There was no significant change in the knee muscle strength in the control group. The vibration-induced corrected Root Mean Squares of the semitendinosus muscle was decreased by 2.8 times (p=0.005) in the exercise group, whereas there was no change in the control group. Sclerostin index was decreased by 15.2% (p=0.031) in the exercise group and increased by 20.8% (p=0.028) in the control group. A change in the sclerostin index was an important predictor of a change in the vibration-induced normalised Root Mean Square of the semitendinosus muscle (R2=0.7, p=0.0001). Femoral neck bone mineral density was an important predictor of muscle strength gain (R2=0.26, p=0.035). This study indicates that bone tissue may have an effect on vibration-induced muscle strength gain and vibration-induced reflex muscle activity. ClinicalTrials.gov: NCT01310348.

Glucosamine-containing supplement improves locomotor functions in subjects with knee pain: a randomized, double-blind, placebo-controlled study

PubMed Central

Kanzaki, Noriyuki; Ono, Yoshiko; Shibata, Hiroshi; Moritani, Toshio

2015-01-01

Background The aim of this study was to investigate the ability of a glucosamine-containing supplement to improve locomotor functions in subjects with knee pain. Methods A randomized, double-blind, placebo-controlled, parallel-group comparative study was conducted for 16 weeks in 100 Japanese subjects (age, 51.8±0.8 years) with knee pain. Subjects were randomly assigned to one of the two supplements containing 1) 1,200 mg of glucosamine hydrochloride, 60 mg of chondroitin sulfate, 45 mg of type II collagen peptides, 90 mg of quercetin glycosides, 10 mg of imidazole peptides, and 5 μg of vitamin D per day (GCQID group, n=50) or 2) a placebo (placebo group, n=50). Japanese Knee Osteoarthritis Measure, visual analog scale score, normal walking speed, and knee-extensor strength were measured to evaluate the effects of the supplement on knee-joint functions and locomotor functions. Results In subjects eligible for efficacy assessment, there was no significant group × time interaction, and there were improvements in knee-joint functions and locomotor functions in both groups, but there was no significant difference between the groups. In subjects with mild-to-severe knee pain at baseline, knee-extensor strength at week 8 (104.6±5.0% body weight vs 92.3±5.5% body weight, P=0.030) and the change in normal walking speed at week 16 (0.11±0.03 m/s vs 0.05±0.02 m/s, P=0.038) were significantly greater in the GCQID group than in the placebo group. Further subgroup analysis based on Kellgren–Lawrence (K–L) grade showed that normal walking speed at week 16 (1.36±0.05 m/s vs 1.21±0.02 m/s, P<0.05) was significantly greater in the GCQID group than in the placebo group in subjects with K–L grade I. No adverse effect of treatment was identified in the safety assessment. Conclusion In subjects with knee pain, GCQID supplementation was effective for relieving knee pain and improving locomotor functions. PMID:26604721

Glucosamine-containing supplement improves locomotor functions in subjects with knee pain: a randomized, double-blind, placebo-controlled study.

PubMed

Kanzaki, Noriyuki; Ono, Yoshiko; Shibata, Hiroshi; Moritani, Toshio

2015-01-01

The aim of this study was to investigate the ability of a glucosamine-containing supplement to improve locomotor functions in subjects with knee pain. A randomized, double-blind, placebo-controlled, parallel-group comparative study was conducted for 16 weeks in 100 Japanese subjects (age, 51.8±0.8 years) with knee pain. Subjects were randomly assigned to one of the two supplements containing 1) 1,200 mg of glucosamine hydrochloride, 60 mg of chondroitin sulfate, 45 mg of type II collagen peptides, 90 mg of quercetin glycosides, 10 mg of imidazole peptides, and 5 μg of vitamin D per day (GCQID group, n=50) or 2) a placebo (placebo group, n=50). Japanese Knee Osteoarthritis Measure, visual analog scale score, normal walking speed, and knee-extensor strength were measured to evaluate the effects of the supplement on knee-joint functions and locomotor functions. In subjects eligible for efficacy assessment, there was no significant group × time interaction, and there were improvements in knee-joint functions and locomotor functions in both groups, but there was no significant difference between the groups. In subjects with mild-to-severe knee pain at baseline, knee-extensor strength at week 8 (104.6±5.0% body weight vs 92.3±5.5% body weight, P=0.030) and the change in normal walking speed at week 16 (0.11±0.03 m/s vs 0.05±0.02 m/s, P=0.038) were significantly greater in the GCQID group than in the placebo group. Further subgroup analysis based on Kellgren-Lawrence (K-L) grade showed that normal walking speed at week 16 (1.36±0.05 m/s vs 1.21±0.02 m/s, P<0.05) was significantly greater in the GCQID group than in the placebo group in subjects with K-L grade I. No adverse effect of treatment was identified in the safety assessment. In subjects with knee pain, GCQID supplementation was effective for relieving knee pain and improving locomotor functions.

What Are Knee Problems?

MedlinePlus

... some knee problems. When living with knee problems, everyone should get range of motion, strength, and aerobic exercise ... Living With Them When living with knee problems, everyone should get three types of exercise regularly: Range-of- ...

Reduced firing rates of high threshold motor units in response to eccentric overload.

PubMed

Balshaw, Tom G; Pahar, Madhu; Chesham, Ross; Macgregor, Lewis J; Hunter, Angus M

2017-01-01

Acute responses of motor units were investigated during submaximal voluntary isometric tasks following eccentric overload (EO) and constant load (CL) knee extension resistance exercise. Ten healthy resistance-trained participants performed four experimental test sessions separated by 5 days over a 20 day period. Two sessions involved constant load and the other two used eccentric overload. EO and CL used both sessions for different target knee eccentric extension phases; one at 2 sec and the other at 4 sec. Maximal voluntary contractions (MVC) and isometric trapezoid efforts for 10 sec at 70% MVC were completed before and after each intervention and decomposed electromyography was used to measure motor unit firing rate. The firing rate of later recruited, high-threshold motor units declined following the 2-sec EO but was maintained following 2sec CL (P < 0.05), whereas MUFR for all motor units were maintained for both loading types following 4-sec extension phases. MVC and rate of force development where maintained following both EO and CL and 2 and 4 sec phases. This study demonstrates a slower firing rate of high-threshold motor units following fast eccentric overload while MVC was maintained. This suggests that there was a neuromuscular stimulus without cost to the force-generating capacity of the knee extensors. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Isokinetic strength assessment offers limited predictive validity for detecting risk of future hamstring strain in sport: a systematic review and meta-analysis.

PubMed

Green, Brady; Bourne, Matthew N; Pizzari, Tania

2018-03-01

To examine the value of isokinetic strength assessment for predicting risk of hamstring strain injury, and to direct future research into hamstring strain injuries. Systematic review. Database searches for Medline, CINAHL, Embase, AMED, AUSPORT, SPORTDiscus, PEDro and Cochrane Library from inception to April 2017. Manual reference checks, ahead-of-press and citation tracking. Prospective studies evaluating isokinetic hamstrings, quadriceps and hip extensor strength testing as a risk factor for occurrence of hamstring muscle strain. Independent search result screening. Risk of bias assessment by independent reviewers using Quality in Prognosis Studies tool. Best evidence synthesis and meta-analyses of standardised mean difference (SMD). Twelve studies were included, capturing 508 hamstring strain injuries in 2912 athletes. Isokinetic knee flexor, knee extensor and hip extensor outputs were examined at angular velocities ranging 30-300°/s, concentric or eccentric, and relative (Nm/kg) or absolute (Nm) measures. Strength ratios ranged between 30°/s and 300°/s. Meta-analyses revealed a small, significant predictive effect for absolute (SMD=-0.16, P=0.04, 95% CI -0.31 to -0.01) and relative (SMD=-0.17, P=0.03, 95% CI -0.33 to -0.014) eccentric knee flexor strength (60°/s). No other testing speed or strength ratio showed statistical association. Best evidence synthesis found over half of all variables had moderate or strong evidence for no association with future hamstring injury. Despite an isolated finding for eccentric knee flexor strength at slow speeds, the role and application of isokinetic assessment for predicting hamstring strain risk should be reconsidered, particularly given costs and specialised training required. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Peak torque and muscle balance in the knees of young U-15 and U-17 soccer athletes playing various tactical positions.

PubMed

Chiamonti Bona, Cleiton; Tourinho Filho, Hugo; Izquierdo, Mikel; Pires Ferraz, Ricardo M; Marques, Mário C

2017-01-01

Soccer is a sport that is practiced worldwide and has been investigated in its various aspects, particularly muscle strength, which is an essential motor skill for sports performance. The objective of this study was to investigate the peak torque and muscle balance on the knee extensor and flexor of young soccer players in the tactical positions of goalkeeper, defender, full back, midfielder, defensive midfielder and striker, as well as to determine which field position has the highest peak torque. Forty-nine male players were recruited and divided into two categories during the preparatory period of the season: the Under-15 (U-15) group (N.=23, mean age 14.7±0.5 years, body mass 58.2±10.5 kg, body height 168.5±7.6 cm), and the Under-17 (U-17) group (N.=26, mean age 16.8±0.4 years, body mass 69.2±7.9 kg, body height 176.2±6.6 cm). The U-17 athletes presented a higher peak torque in all the movements of flexion and extension in the two angular velocities (i.e. 60°/s and 300°/s), but only the dominant knee extensor at 300°/s was significantly different between the two categories as well as the percentage change in peak torque compared between U-15 and U-17 was always above 20%. The peak torque variation in the U-17 category (i.e. mostly above 20%) highlights a higher peak torque compared to U-15 athletes. The muscular deficit of the two categories presented a low average of 10-15%, indicating a good muscle balance between knee extensors and flexors. Finally, goalkeepers and defenders achieved the highest peak torque amongst the field positions.

Strength and hypertrophy responses to constant and decreasing rest intervals in trained men using creatine supplementation.

PubMed

Souza-Junior, Tácito P; Willardson, Jeffrey M; Bloomer, Richard; Leite, Richard D; Fleck, Steven J; Oliveira, Paulo R; Simão, Roberto

2011-10-27

The purpose of the current study was to compare strength and hypertrophy responses to resistance training programs that instituted constant rest intervals (CI) and decreasing rest intervals (DI) between sets over the course of eight weeks by trained men who supplemented with creatine monohydrate (CR). Twenty-two recreationally trained men were randomly assigned to a CI group (n = 11; 22.3 ± 1 years; 77.7 ± 5.4 kg; 180 ± 2.2 cm) or a DI group (n = 11; 22 ± 2.5 years; 75.8 ± 4.9 kg; 178.8 ± 3.4 cm). Subjects in both groups supplemented with CR; the only difference between groups was the rest interval instituted between sets; the CI group used 2 minutes rest intervals between sets and exercises for the entire 8-weeks of training, while the DI group started with a 2 minute rest interval the first two weeks; after which the rest interval between sets was decreased 15 seconds per week (i.e. 2 minutes decreasing to 30 seconds between sets). Pre- and post-intervention maximal strength for the free weight back squat and bench press exercises and isokinetic peak torque were assessed for the knee extensors and flexors. Additionally, muscle cross-sectional area (CSA) of the right thigh and upper arm was measured using magnetic resonance imaging. Both groups demonstrated significant increases in back squat and bench press maximal strength, knee extensor and flexor isokinetic peak torque, and upper arm and right thigh CSA from pre- to post-training (p ≤ 0.0001); however, there were no significant differences between groups for any of these variables. The total volume for the bench press and back squat were significantly greater for CI group versus the DI group. We report that the combination of CR supplementation and resistance training can increase muscular strength, isokinetic peak torque, and muscle CSA, irrespective of the rest interval length between sets. Because the volume of training was greater for the CI group versus the DI group, yet strength gains were similar, the creatine supplementation appeared to bolster adaptations for the DI group, even in the presence of significantly less volume. However, further research is needed with the inclusion of a control group not receiving supplementation combined and resistance training with decreasing rest intervals to further elucidate such hypotheses.

Effect of dietary nitrate supplementation on tolerance to supramaximal intensity intermittent exercise.

PubMed

Aucouturier, Julien; Boissière, Julien; Pawlak-Chaouch, Mehdi; Cuvelier, Grégory; Gamelin, François-Xavier

2015-09-15

Dietary nitrate (NO3(-)) supplementation has been shown to increase exercise tolerance and improve oxidative efficiency during aerobic exercise in healthy subjects. We tested the hypothesis that a 3-day supplementation in beetroot juice (BJ) rich in NO3(-) would improve the tolerance to supramaximal intensity intermittent exercise consisting of 15-s exercise periods at 170% of the maximal aerobic power interspersed with 30-s passive recovery periods. The number of repetitions completed before reaching volitional exhaustion was significantly higher in the BJ than in the placebo condition (26.1 ± 10.7 versus 21.8 ± 8.0 respectively, P < 0.05). In contrast to previous findings during exercise performed at intensity below the peak oxygen uptake (VO2peak), oxygen uptake (VO2) was unaffected (BJ: 2735 ± 345 mL kg(-1) min(-1) vs. placebo: 2787 ± 346 mL kg(-1) min(-1), NS). However, the Area Under the Curve for microvascular total hemoglobin (AUC-THb) in the vastus lateralis muscle assessed by near infrared spectroscopy during 3 time-matched repetitions was significantly increased with NO3(-) supplementation (BJ: 9662 ± 1228 a.u. vs. placebo:8178 ± 1589 a.u.; P < 0.05). Thus, increased NO3(-) (BJ: 421.5 ± 107.4 μM vs placebo:39.4 ± 18.0 μM) and NO2(-) (BJ: 441 ± 184 nM vs placebo: 212 ± 119 nM) plasma levels (P < 0.001 for both) are associated with improved muscle microvascular Red Blood Cell (RBC) concentration and O2 delivery during intense exercise, despite no effect on resting femoral artery blood flow, and vascular conductance. Maximal voluntary force during an isometric leg extensor exercise, and blood lactate levels were also unaffected by NO3(-) supplementation. To conclude, dietary NO3(-) supplementation enhances tolerance to exercise at supramaximal intensity, with increased microvascular total RBC concentration in the working muscle, in the absence of effect on contractile function and resting hemodynamic parameters. Copyright © 2015 Elsevier Inc. All rights reserved.

Analysis of the Response Speed of Musculature of the Knee in Professional Male and Female Volleyball Players

PubMed Central

Rodríguez-Ruiz, D.; Diez-Vega, I.; Rodríguez-Matoso, D.; Fernandez-del-Valle, M.; Sagastume, R.; Molina, J. J.

2014-01-01

The aim of this study was to evaluate the normalized response speed (Vrn) of the knee musculature (flexor and extensor) in high competitive level volleyball players using tensiomyography (TMG) and to analyze the muscular response of the vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL), and biceps femoris (BF) in accordance with the specific position they play in their teams. One hundred and sixty-six players (83 women and 83 men) were evaluated. They belonged to eight teams in the Spanish women's superleague and eight in the Spanish men's superleague. The use of Vrn allows avoiding possible sample imbalances due to anatomical and functional differences and demands. We found differences between Vrn in each of the muscles responsible for extension (VM, RF, and VL) and flexion (BF) regardless of the sex. Normalized response speed differences seem to be larger in setters, liberos and outside players compared to middle blockers and larger in males when compared to females. These results of Vrn might respond to the differences in the physical and technical demands of each specific position, showing an improved balance response of the knee extensor and flexor musculature in male professional volleyball players. PMID:25003109

NOT ALL SINGLE LEG SQUATS ARE EQUAL: A BIOMECHANICAL COMPARISON OF THREE VARIATIONS.

PubMed

Khuu, Anne; Foch, Eric; Lewis, Cara L

2016-04-01

The single leg squat (SLS) is a functional task used by practitioners to evaluate and treat multiple pathologies of the lower extremity. Variations of the SLS may have different neuromuscular and biomechanical demands. The effect of altering the non-stance leg position during the SLS on trunk, pelvic, and lower extremity mechanics has not been reported. The purpose of this study was to compare trunk, pelvic, hip, knee, and ankle kinematics and hip, knee, and ankle kinetics of three variations of the SLS using different non-stance leg positions: SLS-Front, SLS-Middle, and SLS-Back. Sixteen healthy women performed the three SLS tasks while data were collected using a motion capture system and force plates. Joint mechanics in the sagittal, frontal, and transverse planes were compared for the SLS tasks using a separate repeated-measures analysis of variance (ANOVA) for each variable at two analysis points: peak knee flexion (PKF) and 60 ° of knee flexion (60KF). Different non-stance leg positions during the SLS resulted in distinct movement patterns and moments at the trunk, pelvis, and lower extremity. At PKF, SLS-Back exhibited the greatest kinematic differences (p < 0.05) from SLS-Front and SLS-Middle with greater ipsilateral trunk flexion, pelvic anterior tilt and drop, hip flexion and adduction, and external rotation as well as less knee flexion and abduction. SLS-Back also showed the greatest kinetic differences (p < 0.05) from SLS-Front and SLS-Middle with greater hip external rotator moment and knee extensor moment as well as less hip extensor moment and knee adductor moment at PKF. At 60KF, the findings were similar except at the knee. The mechanics of the trunk, pelvis, and lower extremity during the SLS were affected by the position of the non-stance leg in healthy females. Practitioners can use these findings to distinguish between SLS variations and to select the appropriate SLS for assessment and rehabilitation. 3.

Effect of the walking speed to the lower limb joint angular displacements, joint moments and ground reaction forces during walking in water.

PubMed

Miyoshi, Tasuku; Shirota, Takashi; Yamamoto, Shin-ichiro; Nakazawa, Kimitaka; Akai, Masami

2004-06-17

The purpose of this study was to compare the changes in ground reaction forces (GRF), joint angular displacements (JAD), joint moments (JM) and electromyographic (EMG) activities that occur during walking at various speeds in water and on land. Fifteen healthy adults participated in this study. In the water experiments, the water depth was adjusted so that body weight was reduced by 80%. A video-motion analysis system and waterproof force platform was used to obtain kinematics and kinetics data and to calculate the JMs. Results revealed that (1) the anterior-posterior GRF patterns differed between walking in water and walking on land, whereas the medio-lateral GRF patterns were similar, (2) the JAD patterns of the hip and ankle were similar between water- and land-walking, whereas the range of motion at the knee joint was lower in water than on land, (3) the JMs in all three joints were lower in water than on land throughout the stance phase, and (4) the hip joint extension moment and hip extensor muscle EMG activity were increased as walking speed increase during walking in water. Rehabilitative water-walking exercise could be designed to incorporate large-muscle activities, especially of the lower-limb extensor muscles, through full joint range of motion and minimization of joint moments.

Is long-term physical activity safe for older adults with knee pain?: a systematic review.

PubMed

Quicke, J G; Foster, N E; Thomas, M J; Holden, M A

2015-09-01

To determine whether long-term physical activity is safe for older adults with knee pain. A comprehensive systematic review and narrative synthesis of existing literature was conducted using multiple electronic databases from inception until May 2013. Two reviewers independently screened, checked data extraction and carried out quality assessment. Inclusion criteria for study designs were randomised controlled trials (RCTs), prospective cohort studies or case control studies, which included adults of mean age over 45 years old with knee pain or osteoarthritis (OA), undertaking physical activity over at least 3 months and which measured a safety related outcome (adverse events, pain, physical functioning, structural OA imaging progression or progression to total knee replacement (TKR)). Of the 8614 unique references identified, 49 studies were included in the review, comprising 48 RCTs and one case control study. RCTs varied in quality and included an array of low impact therapeutic exercise interventions of varying cardiovascular intensity. There was no evidence of serious adverse events, increases in pain, decreases in physical function, progression of structural OA on imaging or increased TKR at group level. The case control study concluded that increasing levels of regular physical activity was associated with lower risk of progression to TKR. Long-term therapeutic exercise lasting 3 to 30 months is safe for most older adults with knee pain. This evidence supports current clinical guideline recommendations. However, most studies investigated selected, consenting older adults carrying out low impact therapeutic exercise which may affect result generalizability. PROSPERO 2014:CRD42014006913. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Mechanical and biomechanical analysis of a linear piston design for angular-velocity-based orthotic control.

PubMed

Lemaire, Edward D; Samadi, Reza; Goudreau, Louis; Kofman, Jonathan

2013-01-01

A linear piston hydraulic angular-velocity-based control knee joint was designed for people with knee-extensor weakness to engage knee-flexion resistance when knee-flexion angular velocity reaches a preset threshold, such as during a stumble, but to otherwise allow free knee motion. During mechanical testing at the lowest angular-velocity threshold, the device engaged within 2 degrees knee flexion and resisted moment loads of over 150 Nm. The device completed 400,000 loading cycles without mechanical failure or wear that would affect function. Gait patterns of nondisabled participants were similar to normal at walking speeds that produced below-threshold knee angular velocities. Fast walking speeds, employed purposely to attain the angular-velocity threshold and cause knee-flexion resistance, reduced maximum knee flexion by approximately 25 degrees but did not lead to unsafe gait patterns in foot ground clearance during swing. In knee collapse tests, the device successfully engaged knee-flexion resistance and stopped knee flexion with peak knee moments of up to 235.6 Nm. The outcomes from this study support the potential for the linear piston hydraulic knee joint in knee and knee-ankle-foot orthoses for people with lower-limb weakness.

The Effect of Water Temperature during Cold-Water Immersion on Recovery from Exercise-Induced Muscle Damage.

PubMed

Vieira, A; Siqueira, A F; Ferreira-Junior, J B; do Carmo, J; Durigan, J L Q; Blazevich, A; Bottaro, M

2016-11-01

This study investigated the effects of 5 and 15°C cold-water immersion on recovery from exercise resulting in exercise-induced muscle damage. 42 college-aged men performed 5×20 drop-jumps and were randomly allocated into one of 3 groups: (1) 5°C; (2) 15°C; or (3) control. After exercise, individuals from the cold-water immersion groups had their lower limbs immerged in iced water for 20 min. Isometric knee extensor torque, countermovement jump, muscle soreness, and creatine kinase were measured before, immediately after, 24, 48, 72, 96 and 168 h post-exercise. There was no between-group difference in isometric strength recovery (p=0.73). However, countermovement jump recovered quicker in cold-water immersion groups compared to control group (p<0.05). Countermovement jump returned to baseline after 72 h in 15°C, 5°C group recovered after 96 h and control did not recovered at any time point measured. Also, creatine kinase returned to baseline at 72 h and remained stable for all remaining measurements for 15°C group, whereas remained elevated past 168 h in both 5°C and control groups. There was a trend toward lower muscle soreness (p=0.06) in 15°C group compared to control at 24 h post-exercise. The result suggests that cold-water immersion promote recovery of stretch-shortening cycle performance, but not influence the recovery of maximal contractile force. Immersion at warmer temperature may be more effective than colder temperatures promoting recovery from strenuous exercise. © Georg Thieme Verlag KG Stuttgart · New York.

Efficacy of Hip Strengthening Exercises Compared With Leg Strengthening Exercises on Knee Pain, Function, and Quality of Life in Patients With Knee Osteoarthritis.

PubMed

Lun, Victor; Marsh, Andrew; Bray, Robert; Lindsay, David; Wiley, Preston

2015-11-01

The purpose of this study was to compare the efficacy of hip and leg strengthening exercise programs on knee pain, function, and quality of life (QOL) of patients with knee osteoarthritis (KOA). Single-Blinded Randomized Clinical Trial. Patients with KOA. Male and female subjects were recruited from patients referred to the University of Calgary Sport Medicine Center and from newspaper advertisements. Thirty-seven and 35 patients with KOA were randomly assigned to either a 12-week hip or leg strengthening exercise program, respectively. Both exercise programs consisted of strengthening and flexibility exercises, which were completed 3 to 5 days a week. The first 3 weeks of exercise were supervised and the remaining 9 weeks consisted of at-home exercise. Knee Injury and Osteoarthritis Score (KOOS) and Western Ontario McMaster Arthritis Index (WOMAC) questionnaires, 6-minute walk test, hip and knee range of motion (ROM), and hip and leg muscle strength. Statistically and clinically significant improvements in the KOOS and WOMAC pain subscale scores were observed in both the hip and leg strengthening programs. There was no statistical difference in the change in scores observed between the 2 groups. Equal improvements in the KOOS and WOMAC function and QOL subscales were observed for both programs. There was no change in hip and knee ROM or hip and leg strength in either group. Isolated hip and leg strengthening exercise programs seem to similarly improve knee pain, function, and QOL in patients with KOA. The results of this study show that both hip and leg strengthening exercises improve pain and QOL in patients with KOA and should be incorporated into the exercise prescription of patients with KOA.

Two-stage knee arthrodesis with a modular intramedullary nail due to septic failure of revision total knee arthroplasty with extensor mechanism deficiency.

PubMed

Friedrich, Max J; Schmolders, Jan; Wimmer, Matthias D; Strauss, Andreas C; Ploeger, Milena M; Wirtz, Dieter C; Gravius, Sascha; Randau, Thomas M

2017-10-01

Periprosthetic joint infection is a serious complication and reconstruction after failed revision total knee arthroplasty with significant bone loss and compromised soft-tissues can be challenging. Objective of this study was to assess clinical and functional results, implant survival and infection recurrence rates in patients treated with two-stage arthrodesis after failed revision TKA with extensor mechanism deficiencies due to PJI, and to identify the factors that affect outcomes after surgery. Thirty seven patients with PJI treated within a two-stage exchange and reimplantation of an arthrodesis nail between 2008 and 2014 were included. Systemic and local risk factors were graded preoperatively according to McPherson et al. All patients were treated according to a structured treatment algorithm. Clinical and functional evaluation was performed using the Oxford Knee Score and the Visual Analogue Scale. Thirty two of 37 patients (86.5%) were graded as free of infection. Five patients (13.5%) had recurrent infection after arthrodesis with the need of revision surgery. Mean leg-length discrepancy was 2.2cm. The mean VAS for pain was three, the mean Oxford Knee Score was 38±9. Total implant survival at a 74month follow-up was 74.3% (95% CI: 45.4 to 91.1%), as determined by Kaplan-Meier survival curves. Local McPherson Score, as well as number of revisions was found to be of significant influence to the survival rate. Septic failure of revision knee arthroplasty can be effectively treated with two-stage arthrodesis using a modular intramedullary nail, providing a stable and painless limb with satisfactory functional results and acceptable infection eradication rates. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Quadriceps Muscle Fatigue on Stiff-Knee Gait in Patients with Hemiparesis

PubMed Central

Boudarham, Julien; Roche, Nicolas; Pradon, Didier; Delouf, Eric; Bensmail, Djamel; Zory, Raphael

2014-01-01

The relationship between neuromuscular fatigue and locomotion has never been investigated in hemiparetic patients despite the fact that, in the clinical context, patients report to be more spastic or stiffer after walking a long distance or after a rehabilitation session. The aim of this study was to evaluate the effects of quadriceps muscle fatigue on the biomechanical gait parameters of patients with a stiff-knee gait (SKG). Thirteen patients and eleven healthy controls performed one gait analysis before a protocol of isokinetic quadriceps fatigue and two after (immediately after and after 10 minutes of rest). Spatiotemporal parameters, sagittal knee and hip kinematics, rectus femoris (RF) and vastus lateralis (VL) kinematics and electromyographic (EMG) activity were analyzed. The results showed that quadriceps muscle weakness, produced by repetitive concentric contractions of the knee extensors, induced an improvement of spatiotemporal parameters for patients and healthy subjects. For the patient group, the increase in gait velocity and step length was associated with i) an increase of sagittal hip and knee flexion during the swing phase, ii) an increase of the maximal normalized length of the RF and VL and of the maximal VL lengthening velocity during the pre-swing and swing phases, and iii) a decrease in EMG activity of the RF muscle during the initial pre-swing phase and during the latter 2/3 of the initial swing phase. These results suggest that quadriceps fatigue did not alter the gait of patients with hemiparesis walking with a SKG and that neuromuscular fatigue may play the same functional role as an anti-spastic treatment such as botulinum toxin-A injection. Strength training of knee extensors, although commonly performed in rehabilitation, does not seem to be a priority to improve gait of these patients. PMID:24718087

Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production

PubMed Central

Morin, Jean-Benoît; Gimenez, Philippe; Edouard, Pascal; Arnal, Pierrick; Jiménez-Reyes, Pedro; Samozino, Pierre; Brughelli, Matt; Mendiguchia, Jurdan

2015-01-01

Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability. PMID:26733889

Effects of Warm-Up and Fatigue on Knee Joint Position Sense and Jump Performance.

PubMed

Romero-Franco, N; Jiménez-Reyes, P

2017-01-01

The purpose of this study was to evaluate the effects of a warm-up and fatigue protocol on the vertical jump and knee joint position sense of sprinters. Thirty-two sprinters were randomly allocated to either a control group (CONT) or a plyometric group (PLYO) that performed a warm-up, followed by a high-intensity plyometric protocol. Absolute (AAE), relative (RAE), and variable (VAE) angular errors and vertical jump were evaluated before and after the warm-up, as well as after the plyometric protocol and again 5 min later. After the warm-up, athletes improved RAE and jump performance. After the plyometric protocol, scores on the RAE, VAE, and the vertical jump performance worsened compared to the control group and to the values obtained after the warm-up. Five minutes later, RAE and vertical jump continued to be impaired. AAE did not show significant differences. The vertical jump is improved after the warm-up, although it is deteriorated after high-intensity plyometry. Regarding knee proprioception, the lack of impairments in the AAE make unclear the effects of the plyometric exercises on knee proprioception.

The effect of exercise therapy on knee osteoarthritis: a randomized clinical trial

PubMed Central

Nejati, Parisa; Farzinmehr, Azizeh; Moradi-Lakeh, Maziar

2015-01-01

Background: Knee osteoarthritis (OA) is the most common musculoskeletal disease among old individuals which affects ability for sitting on the chair, standing, walking and climbing stairs. Our objective was to investigate the short and long-term effects of the most simple and the least expensive exercise protocols in combination to conventional conservative therapy for knee OA. Methods: It was a single blind RCT study with a 12-months follow-up. Totally, 56 patients with knee OA were assigned into 2 random groups. The patients in exercise group received exercise for knee muscles in combination with non-steroid anti-inflammatory drugs (NSAIDs) and 10 sessions acupuncture and physiotherapy modalities. Non-exercise group received similar treatments except exercise program. The changes in patients’ pain and functional status were evaluated by visual analog scale (VAS), knee and osteoarthritis outcome score (KOOS) questionnaire and functional tests (4 steps, 5 sit up, and 6 min walk test) before and after treatment (1 and 3 months after intervention), and 1 year later at the follow-up. Results: The results showed that the patients with knee OA in exercise group had significant improvement in pain, disability, walking, stair climbing, and sit up speed after treatment at first and second follow-up when compared with their initial status and when compared with non-exercise group. At third follow up (1 year later) there was significant difference between groups in VAS and in three items of KOOS questionnaire in functional status. Conclusion: Non aerobic exercises for muscles around knee can augment the effect of other therapeutic interventions like medical therapy, acupuncture, and modalities for knee OA. PMID:26034739