Impact of Fat Infiltration in Cervical Extensor Muscles on Cervical Lordosis and Neck Pain: A Cross-Sectional Study.

PubMed

Kim, Choong-Young; Lee, Sang-Min; Lim, Seong-An; Choi, Yong-Soo

2018-06-01

Weakness of cervical extensor muscles causes loss of cervical lordosis, which could also cause neck pain. The aim of this study was to investigate the impact of fat infiltration in cervical extensor muscles on cervical lordosis and neck pain. Fifty-six patients who suffered from neck pain were included in this study. Fat infiltration in cervical extensor muscles was measured at each level of C2-3 and C6-7 using axial magnetic resonance imaging. The visual analogue scale (VAS), 12-Item Short Form Health Survey (SF-12), and Neck Disability Index (NDI) were used for clinical assessment. The mean fat infiltration was 206.3 mm 2 (20.3%) at C2-3 and 240.6 mm 2 (19.5%) at C6-7. Fat infiltration in cervical extensor muscles was associated with high VAS scores at both levels ( p = 0.047 at C2-3; p = 0.009 at C6-7). At C2-3, there was a negative correlation between fat infiltration of the cervical extensor muscles and cervical lordosis (r = -0.216; p = 0.020). At C6-7, fat infiltration in the cervical extensor muscles was closely related to NDI ( p = 0.003) and SF-12 ( p > 0.05). However, there was no significant correlation between cervical lordosis and clinical outcomes (VAS, p = 0.112; NDI, p = 0.087; and SF-12, p > 0.05). These results suggest that fat infiltration in the upper cervical extensor muscles has relevance to the loss of cervical lordosis, whereas fat infiltration in the lower cervical extensor muscles is associated with cervical functional disability.

The influence of lumbar extensor muscle fatigue on lumbar-pelvic coordination during weightlifting.

PubMed

Hu, Boyi; Ning, Xiaopeng

2015-01-01

Lumbar muscle fatigue is a potential risk factor for the development of low back pain. In this study, we investigated the influence of lumbar extensor muscle fatigue on lumbar-pelvic coordination patterns during weightlifting. Each of the 15 male subjects performed five repetitions of weightlifting tasks both before and after a lumbar extensor muscle fatiguing protocol. Lumbar muscle electromyography was collected to assess fatigue. Trunk kinematics was recorded to calculate lumbar-pelvic continuous relative phase (CRP) and CRP variability. Results showed that fatigue significantly reduced the average lumbar-pelvic CRP value (from 0.33 to 0.29 rad) during weightlifting. The average CRP variability reduced from 0.17 to 0.15 rad, yet this change ws statistically not significant. Further analyses also discovered elevated spinal loading during weightlifting after the development of lumbar extensor muscle fatigue. Our results suggest that frequently experienced lumbar extensor muscle fatigue should be avoided in an occupational environment. Lumbar extensor muscle fatigue generates more in-phase lumbar-pelvic coordination patterns and elevated spinal loading during lifting. Such increase in spinal loading may indicate higher risk of back injury. Our results suggest that frequently experienced lumbar muscle fatigue should be avoided to reduce the risk of LBP.

Strength deficits identified with concentric action of the hip extensors and eccentric action of the hamstrings predispose to hamstring injury in elite sprinters.

PubMed

Sugiura, Yusaku; Saito, Tomoyuki; Sakuraba, Keishoku; Sakuma, Kazuhiko; Suzuki, Eiichi

2008-08-01

Prospective cohort study. In this prospective cohort study of elite sprinters, muscle strength of the hip extensors, as well as of the knee extensors and flexors, was measured to determine a possible relationship between strength deficits and subsequent hamstring injury within 12 months of testing. The method used for testing muscle strength simulated the specific muscle action during late swing and early contact phases when sprinting. There have been no prospective studies in elite sprinters that examine the concentric and eccentric isokinetic strength of the hip extensors and the quadriceps and hamstring muscles in a manner that reflects their actions in late swing or early contact phases of sprinting. Consequently, the causal relationship between hip and thigh muscle strength and hamstring injury in elite sprinters may not be fully understood. Isokinetic testing was performed on 30 male elite sprinters to assess hip extensors, quadriceps, and hamstring muscle strength. The occurrence of hamstring injury among the subjects was determined during the year following the muscle strength measurements. The strength of the hip extensors, quadriceps, and hamstring muscles, as well as the hamstrings-quadriceps and hip extensors- quadriceps ratios were compared. Hamstring injury occurred in 6 subjects during the 1-year period. Isokinetic testing at a speed of 60 degrees /s revealed weakness of the injured limb with eccentric action of the hamstring muscles and during concentric action of the hip extensors. When performing a side-to-side comparison for the injured sprinters, the hamstring injury always occurred on the weaker side. Differences in the hamstrings-quadriceps and hip extensors-quadriceps strength ratios were also evident between uninjured and injured limbs, and this was attributable to deficits in hamstring strength. Hamstring injury in elite sprinters was associated with weakness during eccentric action of the hamstrings and weakness during concentric action of the hip extensors, but only when tested at the slower speed of 60 degrees /s.

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.

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.

Analysis of muscle fiber conduction velocity during finger flexion and extension after stroke.

PubMed

Conrad, Megan O; Qiu, Dan; Hoffmann, Gilles; Zhou, Ping; Kamper, Derek G

2017-05-01

Stroke survivors experience greater strength deficits during finger extension than finger flexion. Prior research indicates relatively little observed weakness is directly attributable to muscle atrophy. Changes in other muscle properties, however, may contribute to strength deficits. This study measured muscle fiber conduction velocity (MFCV) in a finger flexor and extensor muscle to infer changes in muscle fiber-type after stroke. Conduction velocity was measured using a linear EMG surface electrode array for both extensor digitorum communis and flexor digitorum superficialis in 12 stroke survivors with chronic hand hemiparesis and five control subjects. Measurements were made in both hands for all subjects. Stroke survivors had either severe (n = 5) or moderate (n = 7) hand impairment. Absolute MFCV was significantly lower in the paretic hand of severely impaired stroke patients compared to moderately impaired patients and healthy control subjects. The relative MFCV between the two hands, however, was quite similar for flexor muscles across all subjects and for extensor muscles for the neurologically intact control subjects. However, MFCV for finger extensors was smaller in the paretic as compared to the nonparetic hand for both groups of stroke survivors. One explanation for reduced MFCV may be a type-II to type-I muscle fiber, especially in extrinsic extensors. Clinically, therapists may use this information to develop therapeutic exercises targeting loss of type-II fiber in extensor muscles.

Trunk extensor muscle fatigue influences trunk muscle activities.

PubMed

Hoseinpoor, Tahere Seyed; Kahrizi, Sedighe; Mobini, Bahram

2015-01-01

Trunk muscles fatigue is one of the risk factors in workplaces and daily activities. Loads would be redistributed among active and passive tissues in a non-optimal manner in fatigue conditions. Therefore, a single tissue might be overloaded with minimal loads and as a result the risk of injury would increase. The goal of this paper was to assess the electromyographic response of trunk extensor and abdominal muscles after trunk extensor muscles fatigue induced by cyclic lifting task. This was an experimental study that twenty healthy women participated. For assessing automatic response of trunk extensor and abdominal muscles before and after the fatigue task, electromyographic activities of 6 muscles: thorasic erector spine (TES), lumbar erector spine (LES), lumbar multifidus (LMF), transverse abdominis/ internal oblique (TrA/IO), rectus abdominis (RA) and external oblique (EO) were recorded in standing position with no load and symmetric axial loads equal to 25% of their body weights. Statistical analysis showed that all the abdominal muscles activity decreased with axial loads after performing fatigue task but trunk extensor activity remained constant. Results of the current study indicated that muscle recruitment strategies changed with muscle fatigue and load bearing, therefore risks of tissue injury may increase in fatigue conditions.

Function and structure of the deep cervical extensor muscles in patients with neck pain.

PubMed

Schomacher, Jochen; Falla, Deborah

2013-10-01

The deep cervical extensors are anatomically able to control segmental movements of the cervical spine in concert with the deep cervical flexors. Several investigations have confirmed changes in cervical flexor muscle control in patients with neck pain and as a result, effective evidence-based therapeutic exercises have been developed to address such dysfunctions. However, knowledge on how the deep extensor muscles behave in patients with neck pain disorders is scare. Structural changes such as higher concentration of fat within the muscle, variable cross-sectional area and higher proportions of type II fibres have been observed in the deep cervical extensors of patients with neck pain compared to healthy controls. These findings suggest that the behaviour of the deep extensors may be altered in patients with neck pain. Consistent with this hypothesis, a recent series of studies confirm that patients display reduced activation of the deep cervical extensors as well as less defined activation patterns. This article provides an overview of the various different structural and functional changes in the deep neck extensor muscles documented in patients with neck pain. Relevant recommendations for the management of muscle dysfunction in patients with neck pain are presented. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gravitational unloading effects on muscle fiber size, phenotype and myonuclear number

NASA Technical Reports Server (NTRS)

Ohira, Y.; Yoshinaga, T.; Nomura, T.; Kawano, F.; Ishihara, A.; Nonaka, I.; Roy, R. R.; Edgerton, V. R.

2002-01-01

The effects of gravitational unloading with or without intact neural activity and/or tension development on myosin heavy chain (MHC) composition, cross-sectional area (CSA), number of myonuclei, and myonuclear domain (cytoplasmic volume per myonucleus ratio) in single fibers of both slow and fast muscles of rat hindlimbs are reviewed briefly. The atrophic response to unloading is generally graded as follows: slow extensors > fast extensors > fast flexors. Reduction of CSA is usually greater in the most predominant fiber type of that muscle. The percentage of fibers expressing fast MHC isoforms increases in unloaded slow but not fast muscles. Myonuclear number per mm of fiber length and myonuclear domain is decreased in the fibers of the unloaded predominantly slow soleus muscle, but not in the predominantly fast plantaris. Decreases in myonuclear number and domain, however, are observed in plantaris fibers when tenotomy, denervation, or both are combined with hindlimb unloading. All of these results are consistent with the view that a major factor for fiber atrophy is an inhibition or reduction of loading of the hindlimbs. These data also indicate that predominantly slow muscles are more responsive to unloading than predominantly fast muscles. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

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.

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

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.

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

MRI-determined lumbar muscle morphometry in man and sheep: potential biomechanical implications for ovine model to human spine translation.

PubMed

Valentin, Stephanie; Licka, Theresia F; Elliott, James

2015-10-01

The sheep is a commonly used animal model for human lumbar spine surgery, but only in vitro investigations comparing the human and ovine spine exist. Spinal musculature has previously not been compared between man and sheep. This additional knowledge could further indicate to what extent these species are biomechanically similar. Therefore, the purpose of the study was to investigate spinal muscle morphometric properties using magnetic resonance imaging (MRI) in different age groups of healthy human participants and sheep in vivo. Healthy human participants (n = 24) and sheep (n = 17) of different age groups underwent T1-weighted MRI of the lumbar spine. Regions of interest of the muscles erector spinae (ES), multifidus (M) and psoas (PS) were identified. The ratio of flexor to extensor volume, ratio of M to ES volume, and muscle fat relative to an area of intermuscular fat were calculated. Sheep M to ES ratio was significantly smaller than in the human participants (sheep 0.16 ± 0.02; human 0.37 ± 0.05; P < 0.001), although flexor to extensor ratio was not significantly different between species (human 0.39 ± 0.08; sheep 0.43 ± 0.05; P = 0.06). Age did not influence any muscle ratio outcome. Sheep had significantly greater extensor muscle fat compared with the human participants (M left human 40.64%, sheep 53.81%; M right human 39.17%, sheep 51.33%; ES left human 40.86%, sheep 51.29%; ES right human 35.93%, sheep 44.38%; all median values; all P < 0.001), although PS did not show any significant between-species differences (PS left human 36.89%, sheep 33.67%; PS right human 32.78%, sheep 30.09%; P < 0.05). The apparent differences in the size and shape of sheep and human lumbar spine muscles may indicate dissimilar biomechanical and functional demands, which is an important consideration when translating to human surgical models. © 2015 Anatomical Society.

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.

Handgrip strength deficits best explain limitations in performing bimanual activities after stroke.

PubMed

Basílio, Marluce Lopes; de Faria-Fortini, Iza; Polese, Janaine Cunha; Scianni, Aline A; Faria, Christina Dcm; Teixeira-Salmela, Luci Fuscaldi

2016-04-01

[Purpose] To evaluate the relationships between residual strength deficits (RSD) of the upper limb muscles and the performance in bimanual activities and to determine which muscular group would best explain the performance in bimanual activities of chronic stroke individuals. [Subjects and Methods] Strength measures of handgrip, wrist extensor, elbow flexor/extensor, and shoulder flexor muscles of 107 subjects were obtained and expressed as RSD. The performance in bimanual activities was assessed by the ABILHAND questionnaire. [Results] The correlations between the RSD of handgrip and wrist extensor muscles with the ABILHAND scores were negative and moderate, whereas those with the elbow flexor/extensor and shoulder flexor muscles were negative and low. Regression analysis showed that the RSD of handgrip and wrist extensor muscles explained 38% of the variance in the ABILHAND scores. Handgrip RSD alone explained 33% of the variance. [Conclusion] The RSD of the upper limb muscles were negatively associated with the performance in bimanual activities and the RSD of handgrip muscles were the most relevant variable. It is possible that stroke subjects would benefit from interventions aiming at improving handgrip strength, when the goal is to increase the performance in bimanual activities.

The effects of trunk extensor and abdominal muscle fatigue on postural control and trunk proprioception in young, healthy individuals.

PubMed

Larson, Dennis J; Brown, Stephen H M

2018-02-01

The purpose of this study was to induce both trunk extensor and abdominal muscle fatigue, on separate occasions, and compare their effects on standing postural control and trunk proprioception, as well as look at the effects of a recovery period on these outcome measures. A total of 20 individuals participated, with 10 (5 males and 5 females) completing either a standing postural control or lumbar axial repositioning protocol. Participants completed their randomly assigned protocol on two occasions, separated by at least 4  days, with either their trunk extensor or abdominal muscles being fatigued on either day. Postural control centre of pressure variables and trunk proprioception errors were compared pre- and post-fatigue. Results showed that both trunk extensor and abdominal muscle fatigue significantly degraded standing postural control immediately post-fatigue, with recovery occurring within 2 min post-fatigue. In general, these degradative effects on postural control appeared to be greater when the trunk extensor muscles were fatigued compared to the abdominal muscles. No statistically significant changes in trunk proprioception were found after either fatigue protocol. The present findings demonstrate our body's ability to quickly adapt and reweight somatosensory information to maintain postural control and trunk proprioception, as well as illustrate the importance of considering the abdominal muscles, along with the trunk extensor muscles, when considering the impact of fatigue on trunk movement and postural control. Copyright © 2017 Elsevier B.V. All rights reserved.

Feed artery role in blood flow control to rat hindlimb skeletal muscles.

PubMed Central

Williams, D A; Segal, S S

1993-01-01

1. Vasomotor tone and reactivity were investigated in feed arteries of the extensor digitorum longus and soleus muscles. Feed arteries are located external to the muscle and give rise to the microcirculation within each muscle. Resting diameter was smaller in feed arteries of the soleus muscle. 2. Feed arteries of both muscles dilated to similar peak values with sodium nitroprusside. 3. Micropressure measurements demonstrated resistance to blood flow in the feed arteries supplying both muscles. Feed arteries supplying soleus muscle demonstrated greater resistance to blood flow compared to feed arteries of extensor digitorum longus muscle. 4. Greater resting tone and larger pressure drop for feed arteries of soleus muscle suggest greater range of flow control compared to feed arteries of extensor digitorum longus muscle. 5. In both muscles, feed artery diameter increased with muscle contraction (functional dilatation) and in response to transient ischaemia (reactive dilatation). The magnitude of these responses varied between muscles. 6. Feed arteries are active sites of blood flow control in extensor digitorum longus and soleus muscles of the rat. These muscles differ in fibre type and recruitment properties. Differences in feed artery reactivity may contribute to differences in blood flow between these muscles observed at rest and during exercise. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8246199

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.

Transfer of extensor carpi radialis brevis as an extensor to extensor motor transfer (EEMT) in ulnar nerve palsy.

PubMed

Jamali, Allah Rakha; Bhatti, Anisuddin; Mehboob, Ghulam

2006-07-01

To evaluate functional outcome and correction of deformity with extensor carpiradialis brevis motor transfer to replace the intrinsic muscles as an extensor to extensor motor transfer (EEMT). This was a prospective observational study with one group pretest posttest design conducted from 1996 to 2004. Convenience sampling technique was used and the sample size was twenty one. The independent variable was transfer of extensor carpiradialis brevis to replace the intrinsic muscles. The dependent variable was functional outcome and the correction of deformity. The extraneous variables were age, sex interval between injury and transfer as well as local factors related to wound and grafts used. The average follow up was 22.5 months. The mean preoperative unassisted extensor lag was 56.79 +/- 10.39 which improved to 9.6% +/- 5.4 (correction of 83%) at six months after surgery. With open hand assessment 76.19% reported good to excellent results, while 79.89% achieved good to excellent results with closed hand assessment. The mechanism of closing was good to excellent in 89.42% cases, however only 71.42% patients considered their hands good to excellent. Significant problems were seen with use of tendoachilles as a graft. Extensor carpiradialis brevis transfer to replace the intrinsic muscles as an extensor to extensor motor transfer can achieve good functional outcome as well as correction of deformity despite shortcomings in physical rehabilitation.

Analysis of elbow muscle strength parameters in Brazilian jiu-jitsu practitioners.

PubMed

Follmer, Bruno; Dellagrana, Rodolfo André; de Lima, Luis Antonio Pereira; Herzog, Walter; Diefenthaeler, Fernando

2017-12-01

Upper-body dynamic and isometric maximum strength are essential components for success in Brazilian jiu-jitsu (BJJ). This study was aimed at analysing strength parameters in the elbow flexor and extensor muscles of BJJ practitioners. Participants (n = 28) performed maximum isometric contractions of elbow flexors and extensors to determine peak torque (PT), rate of force development (RFD), and the torque-angle (T-A) relationship at elbow angles of 45°, 60°, 75°, 90°, 105°, and 120°. Additionally, concentric and eccentric PTs were measured at 1.04 rad·s -1 . Student t-test and ANOVA were performed using α = 0.05. Elbow flexors were stronger isometrically (P < 0.001, ES = 1.23) but weaker concentrically (P < 0.05, ES = 0.54) than extensor muscles, possibly because of the extensive grip disputes and pushing of opponents in BJJ. The T-A relationship had an inverted "U"-shape. Torque differences across elbow angles were moderate (ES = 0.62) for the extensor and large (ES = 0.92) for the flexor muscles. Isometric torque was greatest for elbow angles of 105° and 75° and smallest for 45° and 120° for extensor and flexor muscles, respectively. Elbow flexors had a greater RFD than extensors, regardless of elbow angle. The present study provides comprehensive results for elbow muscle strength in BJJ practitioners.

Elbow flexor and extensor muscle weakness in lateral epicondylalgia.

PubMed

Coombes, Brooke K; Bisset, Leanne; Vicenzino, Bill

2012-05-01

To evaluate whether deficits of elbow flexor and extensor muscle strength exist in lateral epicondylalgia (LE) in comparison with a healthy control population. Cross-sectional study. 150 participants with unilateral LE were compared with 54 healthy control participants. Maximal isometric elbow flexion and extension strength were measured bilaterally using a purpose-built standing frame such that gripping was avoided. The authors found significant side differences in elbow extensor (-6.54 N, 95% CI -11.43 to -1.65, p=0.008, standardised mean difference (SMD) -0.45) and flexor muscle strength (-11.26 N, 95% CI -19.59 to -2.94, p=0.009, SMD -0.46) between LE and control groups. Within the LE group, only elbow extensor muscle strength deficits between sides was significant (affected-unaffected: -2.94 N, 95% CI -5.44 to -0.44). Small significant deficits of elbow extensor and flexor muscle strength exist in the affected arm of unilateral LE in comparison with healthy controls. Notably, comparing elbow strength between the affected and unaffected sides in unilateral epicondylalgia is likely to underestimate these deficits. Trial Registration Australian New Zealand Clinical Trials Register ACTRN12609000051246.

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

Muscular hypertrophy and atrophy in normal rats provoked by the administration of normal and denervated muscle extracts.

PubMed

Agüera, Eduardo; Castilla, Salvador; Luque, Evelio; Jimena, Ignacio; Leiva-Cepas, Fernando; Ruz-Caracuel, Ignacio; Peña, José

2016-12-01

This study was conducted to determine the effects of extracts obtained from both normal and denervated muscles on different muscle types. Wistar rats were used and were divided into a control group and four experimental groups. Each experimental group was treated intraperitoneally during 10 consecutive days with a different extract. These extracts were obtained from normal soleus muscle, denervated soleus, normal extensor digitorum longus, and denervated extensor digitorum longus. Following treatment, the soleus and extensor digitorum longus muscles were obtained for study under optic and transmission electron microscope; morphometric parameters and myogenic responses were also analyzed. The results demonstrated that the treatment with normal soleus muscle and denervated soleus muscle extracts provoked hypertrophy and increased myogenic activity. In contrast, treatment with extracts from the normal and denervated EDL had a different effect depending on the muscle analyzed. In the soleus muscle it provoked hypertrophy of type I fibers and increased myogenic activity, while in the extensor digitorum longus atrophy of the type II fibers was observed without changes in myogenic activity. This suggests that the muscular responses of atrophy and hypertrophy may depend on different factors related to the muscle type which could be related to innervation.

Is the Sørensen test valid to assess muscle fatigue of the trunk extensor muscles?

PubMed

Demoulin, Christophe; Boyer, Mathieu; Duchateau, Jacques; Grosdent, Stéphanie; Jidovtseff, Boris; Crielaard, Jean-Michel; Vanderthommen, Marc

2016-01-01

Very few studies have quantified the degree of fatigue characterized by the decline in the maximal voluntary contraction (MVC) force of the trunk extensors induced by the widely used Sørensen test. Measure the degree of fatigue of the trunk extensor muscles induced by the Sørensen test. Eighty young healthy subjects were randomly divided into a control group (CG) and an experimental group (EG), each including 50% of the two genders. The EG performed an isometric MVC of the trunk extensors (pre-fatigue test) followed by the Sørensen test, the latter being immediately followed by another MVC (post-fatigue test). The CG performed only the pre- and post-fatigue tests without any exertion in between. The comparison of the pre- and post-fatigue tests revealed a significant (P< 0.05) decrease in MVC force normalized by body mass (-13%) in the EG, whereas a small increase occurred in the CG (+2.7%, P= 0.001). This study shows that the Sørensen test performed until failure in a young healthy population results in a reduced ability of the trunk extensor muscles to generate maximal force, and indicates that this test is valid for the assessment of fatigue in trunk extensor muscles.

Reduction-oxidation state and protein degradation in skeletal muscle of fasted and refed rats

NASA Technical Reports Server (NTRS)

Fagan, Julie M.; Tischler, Marc E.

1986-01-01

Redox state and protein degradation were measured in isolated muscles of fasted (up to 10 d) and refed (up to 4 d) 7- to 14-wk-old rats. Protein degradation in the extensor digitorum longus muscle, but not in the soleus muscle, was greater in the fasted rats than in weight-matched muscle from fed rats. The NAD couple was more oxidized in incubated and fresh extensor digitorum longus muscles and in some incubated soleus muscles of fasted rats than in weight-matched muscle from fed rats. In the extensor digitorum longus muscle of refed or prolonged fasted rats, protein degradation was slower and the NAD couple was more reduced than in the fed state. Therefore, oxidation of the NAD couple was associated with increased muscle breakdown during fasting, whereas reduction of the NAD couple was associated with muscle conservation and deposition.

Activation amplitude and temporal synchrony among back extensor and abdominal muscles during a controlled transfer task: comparison of men and women.

PubMed

Hubley-Kozey, Cheryl L; Butler, Heather L; Kozey, John W

2012-08-01

Muscle synergies are important for spinal stability, but few studies examine temporal responses of spinal muscles to dynamic perturbations. This study examined activation amplitudes and temporal synergies among compartments of the back extensor and among abdominal wall muscles in response to dynamic bidirectional moments of force. We further examined whether responses were different between men and women. 19 women and 18 men performed a controlled transfer task. Surface electromyograms from bilateral sites over 6 back extensor compartments and 6 abdominal wall muscle sites were analyzed using principal component analysis. Key features were extracted from the measured electromyographic waveforms capturing amplitude and temporal variations among muscle sites. Three features explained 97% of the variance. Scores for each feature were computed for each measured waveform and analysis of variance found significant (p<.05) muscle main effects and a sex by muscle interaction. For the back extensors, post hoc analysis revealed that upper and more medial sites were recruited to higher amplitudes, medial sites responded to flexion moments, and the more lateral sites responded to lateral flexion moments. Women had more differences among muscle sites than men for the lateral flexion moment feature. For the abdominal wall muscles the oblique muscles responded with synergies related to fiber orientation, with women having higher amplitudes and more responsiveness to the lateral flexion moment than men. Synergies between the abdominal and back extensor sites as the moment demands change are discussed. These findings illustrate differential activation among erector spinae compartments and abdominal wall muscle sites supporting a highly organized pattern of response to bidirectional external moments with asynchronies more apparent in women. Copyright © 2012 Elsevier B.V. All rights reserved.

[Pattern of paralysis and reconstructive operations after traumatic brachial plexus lesions].

PubMed

Rühmann, O; Schmolke, S; Carls, J; Wirth, C J

2002-12-01

The aim of this study was to evaluate persistent patterns of paralysis after traumatic brachial plexus lesions. As a result, consecutive reconstructive operations according to our differential therapy concept are presented. Between 04/1994 and 12/2000 in 104 patients with brachial plexus palsy, the grade of muscle power of the affected upper extremities was evaluated prospectively. The neuromuscular patterns of defect showed, in most cases, insufficient muscle power grades of 0-2 for the deltoid muscle (90%), supraspinatus muscle (82%), infraspinatus muscle (93%), elbow flexors (67% to 77%), hand and finger extensors (69% to 71%), and the abductor and extensors of the thumb (67% to 70%). In corresponding frequency, the following operations were performed between 04/1994 and 06/2002: shoulder arthrodesis (n 26), trapezius transfer (n 80), rotation osteotomy of humerus (n 10), triceps to biceps transposition (n 11), transposition of forearm flexors or extensors/Steindler operation (n 12), latissimus transfer (n 7), pectoralis transfer (n 1), teres major transfer (n 1), transposition of forearm flexors to the tendons of extensor digitorum (n 19) and of the extensor pollicis longus (n 9), and wrist arthrodesis (n 5). On malfunction of muscles following brachial plexus lesions, taking into account the individual neuromuscular defect, passive joint function, and bony deformities, different procedures such as muscle transposition, arthrodesis, and corrective osteotomy can be performed to improve function of the upper extremity.

Effects of dexamethasone treatment on insulin-stimulated rates of glycolysis and glycogen synthesis in isolated incubated skeletal muscles of the rat.

PubMed Central

Leighton, B; Challiss, R A; Lozeman, F J; Newsholme, E A

1987-01-01

1. Rats were treated with dexamethasone for 4 days before measurement of the rates of lactate formation [which is an index of hexose transport; see Challiss, Lozeman, Leighton & Newsholme (1986) Biochem. J. 233, 377-381] and glycogen synthesis in response to various concentrations of insulin in isolated incubated soleus and extensor digitorum longus muscle preparations. 2. The concentration of insulin required to stimulate these processes half-maximally in soleus and extensor digitorum longus muscles isolated from control rats was about 100 muunits/ml. 3. Dexamethasone increases the concentration of insulin required to stimulate glycolysis half-maximally in soleus and extensor digitorum longus preparations to 250 and 300 muunits/ml respectively. The respective insulin concentrations necessary to stimulate glycogen synthesis half-maximally were about 430 and 370 muunits/ml for soleus and extensor digitorum longus muscle preparations isolated from steroid-treated rats. 5. Dexamethasone treatment did not change the amount of insulin bound to soleus muscle. PMID:3318810

Validity and test–retest reliability of a novel simple back extensor muscle strength test

PubMed Central

Harding, Amy T; Weeks, Benjamin Kurt; Horan, Sean A; Little, Andrew; Watson, Steven L; Beck, Belinda Ruth

2017-01-01

Objectives: To develop and determine convergent validity and reliability of a simple and inexpensive clinical test to quantify back extensor muscle strength. Methods: Two testing sessions were conducted, 7 days apart. Each session involved three trials of standing maximal isometric back extensor muscle strength using both the novel test and isokinetic dynamometry. Lumbar spine bone mineral density was examined by dual-energy X-ray absorptiometry. Validation was examined with Pearson correlations (r). Test–retest reliability was examined with intraclass correlation coefficients and limits of agreement. Pearson correlations and intraclass correlation coefficients are presented with corresponding 95% confidence intervals. Linear regression was used to examine the ability of peak back extensor muscle strength to predict indices of lumbar spine bone mineral density and strength. Results: A total of 52 healthy adults (26 men, 26 women) aged 46.4 ± 20.4 years were recruited from the community. A strong positive relationship was observed between peak back extensor strength from hand-held and isokinetic dynamometry (r = 0.824, p < 0.001). For the novel back extensor strength test, short- and long-term reliability was excellent (intraclass correlation coefficient = 0.983 (95% confidence interval, 0.971–0.990), p < 0.001 and intraclass correlation coefficient = 0.901 (95% confidence interval, 0.833–0.943), p < 0.001, respectively). Limits of agreement for short-term repeated back extensor strength measures with the novel back extensor strength protocol were −6.63 to 7.70 kg, with a mean bias of +0.71 kg. Back extensor strength predicted 11% of variance in lumbar spine bone mineral density (p < 0.05) and 9% of lumbar spine index of bone structural strength (p < 0.05). Conclusion: Our novel hand-held dynamometer method to determine back extensor muscle strength is quick, relatively inexpensive, and reliable; demonstrates initial convergent validity in a healthy population; and is associated with bone mass at a clinically important site. PMID:28255442

The influence of Task-Related Training combined with Transcutaneous Electrical Nerve Stimulation on paretic upper limb muscle activation in patients with chronic stroke.

PubMed

Jung, Kyoungsim; Jung, Jinhwa; In, Taesung; Kim, Taehoon; Cho, Hwi-Young

2017-01-01

This study investigated the efficacy of Task-Related Training (TRT) Combined with Transcutaneous Electrical Nerve Stimulation (TENS) on the improvement of upper limb muscle activation in chronic stroke survivors with mild or moderate paresis. A single-blind, randomized clinical trial was conducted with 46stroke survivors with chronic paresis. They were randomly allocated two groups: the TRT+TENS group (n = 23) and the TRT+ placebo TENS (TRT+PLBO) group (n = 23). The TRT+TENS group received 30 minutes of high-frequency TENS on wrist and elbow extensors, while the TRT+PLBO group received placebo TENS that was not real ES. Both groups did 30 minutes of TRT after TENS application. Intervention was given five days a week for four weeks. The primary outcomes of upper limb muscle activation were measured by integrated EMG (IEMG), a digital manual muscle tester for muscle strength, active range of motion (AROM) and Fugl-Meyer Assessment of the upper extremity (FMA-UE). The measurements were performed before and after the 4 weeks intervention period. Both groups demonstrated significant improvements of outcomes in IEMG, AROM, muscle strength and FMA-UE during intervention period. When compared with the TRT+PLBO group, the TRT+TENS group showed significantly greater improvement in muscle activation (wrist extensors, P = 0.045; elbow extensors, P = 0.004), muscle strength (wrist extensors, P = 0.044; elbow extensors, P = 0.012), AROM (wrist extension, P = 0.042; elbow extensors, P = 0.040) and FMA-UE (total, P < 0.001; shoulder/elbow/forearm, P = 0.001; wrist, P = 0.002; coordination, P = 0.008) at the end of intervention. Our findings indicate that TRT Combined with TENS can improve paretic muscle activity in upper limb paresis, highlighting the benefits of somatosensory stimulation from TENS.

Muscle Hypertrophy in Prepubescent Tennis Players: A Segmentation MRI Study

PubMed Central

Sanchis-Moysi, Joaquin; Idoate, Fernando; Serrano-Sanchez, Jose A.; Dorado, Cecilia; Calbet, Jose A. L.

2012-01-01

Purpose To asses if tennis at prepubertal age elicits the hypertrophy of dominant arm muscles. Methods The volume of the muscles of both arms was determined using magnetic resonance imaging (MRI) in 7 male prepubertal tennis players (TP) and 7 non-active control subjects (CG) (mean age 11.0±0.8 years, Tanner 1–2). Results TP had 13% greater total muscle volume in the dominant than in the contralateral arm. The magnitude of inter-arm asymmetry was greater in TP than in CG (13 vs 3%, P<0.001). The dominant arm of TP was 16% greater than the dominant arm of CG (P<0.01), whilst non-dominant arms had similar total muscle volumes in both groups (P = 0.25), after accounting for height as covariate. In TP, dominant deltoid (11%), forearm supinator (55%) and forearm flexors (21%) and extensors (25%) were hypertrophied compared to the contralateral arm (P<0.05). In CG, the dominant supinator muscle was bigger than its contralateral homonimous (63%, P<0.05). Conclusions Tennis at prepubertal age is associated with marked hypertrophy of the dominant arm, leading to a marked level of asymmetry (+13%), much greater than observed in non-active controls (+3%). Therefore, tennis particpation at prepubertal age is associated with increased muscle volumes in dominant compared to the non-dominant arm, likely due to selectively hypertrophy of the loaded muscles. PMID:22428074

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.

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.

Reduced servo-control of fatigued human finger extensor and flexor muscles.

PubMed Central

Hagbarth, K E; Bongiovanni, L G; Nordin, M

1995-01-01

1. In healthy human subjects holding the index finger semi-extended at the metacarpophalangeal joint against a moderate load, electromyographic (EMG) activity was recorded from the finger extensor and flexor muscles during different stages of muscle fatigue. The aim was to study the effect of muscle fatigue on the level of background EMG activity and on the reflex responses to torque pulses causing sudden extensor unloadings. Paired comparisons were made between the averaged EMG and finger deflection responses under two conditions: (1) at a stage of fatigue (following a sustained co-contraction) when great effort was required to maintain the finger position, and (2) under non-fatigue conditions while the subject tried to produce similar background EMG levels to those in the corresponding fatigue trials. 2. Both the unloading reflex in the extensor and the concurrent stretch reflex in the flexor were significantly less pronounced and had a longer latency in the fatigue trials. Consequently, the finger deflections had a larger amplitude and were arrested later in the fatigue trials. 3. It is concluded that--with avoidance of 'automatic gain compensation', i.e. reflex modifications attributable to differences in background EMG levels--the servo-like action of the unloading and stretch reflexes is reduced in fatigued finger extensor and flexor muscles. PMID:7562624

Anatomical association between wrist extensor musculature and topographical pain sensitivity maps of the elbow area.

PubMed

Prados-Frutos, Juan Carlos; Ruiz-Ruiz, Beatriz; De-la-Llave-Rincón, Ana Isabel; Arendt-Nielsen, Lars; Madeleine, Pascal; Fernández-de-Las-Peñas, César

2012-06-01

High-density topographical sensitivity maps have been developed to visualize nonuniformity deep tissue pain sensitivity in, for example, lateral epicondylitis (LE). The aim of this cadaveric study was to determine the anatomical association between the topographical sensitivity maps over the elbow area and wrist extensor musculature. A topographical pressure sensitivity map consisting of 12 points forming a 3 × 4 matrix: 4 points in the superior part, 4 points in the middle, and 4 points in the lower part around the lateral epicondyle was marker on a 50-year embalmed cadaver. Color marker pins were inserted into each point. Pins were removed during the process of dissection, but the small holes created by their removal assured accurate relocation. Progressive dissection revealed that points 1 to 4 (superior line) were placed over the musculotendinous junction and belly of the extensor carpi radialis brevis (ECRB) muscle, points 6 to 8 (middle line) were placed over the musculotendinous junction and belly of the extensor digitorum communis muscle, and points 9 to 12 (inferior line) were located over the musculotendinous junction and belly of the extensor carpi ulnaris muscle. It was also observed that the superficial branch of the radial nerve runs between the belly of the ECRB and extensor digitorum communis muscles. This study confirmed that anatomical location previously assumed supporting the important wrist extensor muscles, particularly the ECRB, in patients with LE as depicted by pressure pain sensitivity maps. This study also suggests a potential role of the superficial branch of the radial nerve in LE. Copyright © 2012 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

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.

Eccentric activation and muscle damage: biomechanical and physiological considerations during downhill running.

PubMed Central

Eston, R G; Mickleborough, J; Baltzopoulos, V

1995-01-01

An eccentric muscle activation is the controlled lengthening of the muscle under tension. Functionally, most leg muscles work eccentrically for some part of a normal gait cycle, to support the weight of the body against gravity and to absorb shock. During downhill running the role of eccentric work of the 'anti-gravity' muscles--knee extensors, muscles of the anterior and posterior tibial compartments and hip extensors--is accentuated. The purpose of this paper is to review the relationship between eccentric muscle activation and muscle damage, particularly as it relates to running, and specifically, downhill running. PMID:7551767

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.

Ischemia causes muscle fatigue

NASA Technical Reports Server (NTRS)

Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D. M.

2001-01-01

The purpose of this investigation was to determine whether ischemia, which reduces oxygenation in the extensor carpi radialis (ECR) muscle, causes a reduction in muscle force production. In eight subjects, muscle oxygenation (TO2) of the right ECR was measured noninvasively and continuously using near infrared spectroscopy (NIRS) while muscle twitch force was elicited by transcutaneous electrical stimulation (1 Hz, 0.1 ms). Baseline measurements of blood volume, muscle oxygenation and twitch force were recorded continuously, then a tourniquet on the upper arm was inflated to one of five different pressure levels: 20, 40, 60 mm Hg (randomized order) and diastolic (69 +/- 9.8 mm Hg) and systolic (106 +/- 12.8 mm Hg) blood pressures. Each pressure level was maintained for 3-5 min, and was followed by a recovery period sufficient to allow measurements to return to baseline. For each respective tourniquet pressure level, mean TO2 decreased from resting baseline (100% TO2) to 99 +/- 1.2% (SEM), 96 +/- 1.9%, 93 +/- 2.8%, 90 +/- 2.5%, and 86 +/- 2.7%, and mean twitch force decreased from resting baseline (100% force) to 99 +/- 0.7% (SEM), 96 +/- 2.7%, 93 +/- 3.1%, 88 +/- 3.2%, and 86 +/- 2.6%. Muscle oxygenation and twitch force at 60 mm Hg tourniquet compression and above were significantly lower (P < 0.05) than baseline value. Reduced twitch force was correlated in a dose-dependent manner with reduced muscle oxygenation (r = 0.78, P < 0.001). Although the correlation does not prove causation, the results indicate that ischemia leading to a 7% or greater reduction in muscle oxygenation causes decreased muscle force production in the forearm extensor muscle. Thus, ischemia associated with a modest decline in TO2 causes muscle fatigue.

Volume regulation in mammalian skeletal muscle: the role of sodium-potassium-chloride cotransporters during exposure to hypertonic solutions.

PubMed

Lindinger, Michael I; Leung, Matthew; Trajcevski, Karin E; Hawke, Thomas J

2011-06-01

Controversy exists as to whether mammalian skeletal muscle is capable of volume regulation in response to changes in extracellular osmolarity despite evidence that muscle fibres have the required ion transport mechanisms to transport solute and water in situ. We addressed this issue by studying the ability of skeletal muscle to regulate volume during periods of induced hyperosmotic stress using single, mouse extensor digitorum longus (EDL) muscle fibres and intact muscle (soleus and EDL). Fibres and intact muscles were loaded with the fluorophore, calcein, and the change in muscle fluorescence and width (single fibres only) used as a metric of volume change. We hypothesized that skeletal muscle exposed to increased extracellular osmolarity would elicit initial cellular shrinkage followed by a regulatory volume increase (RVI) with the RVI dependent on the sodium–potassium–chloride cotransporter (NKCC). We found that single fibres exposed to a 35% increase in extracellular osmolarity demonstrated a rapid, initial 27–32% decrease in cell volume followed by a RVI which took 10-20 min and returned cell volume to 90–110% of pre-stimulus values. Within intact muscle, exposure to increased extracellular osmolarity of varying degrees also induced a rapid, initial shrinkage followed by a gradual RVI, with a greater rate of initial cell shrinkage and a longer time for RVI to occur with increasing extracellular tonicities. Furthermore, RVI was significantly faster in slow-twitch soleus than fast-twitch EDL. Pre-treatment of muscle with bumetanide (NKCC inhibitor) or ouabain (Na+,K+-ATPase inhibitor), increased the initial volume loss and impaired the RVI response to increased extracellular osmolarity indicating that the NKCC is a primary contributor to volume regulation in skeletal muscle. It is concluded that mouse skeletal muscle initially loses volume then exhibits a RVI when exposed to increases in extracellular osmolarity. The rate of RVI is dependent on the degree of change in extracellular osmolarity, is muscle specific, and is dependent on the functioning of the NKCC and Na+, K+-ATPase.

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

Activity patterns of extrinsic finger flexors and extensors during movements of instructed and non-instructed fingers.

PubMed

van Beek, Nathalie; Stegeman, Dick F; van den Noort, Josien C; H E J Veeger, DirkJan; Maas, Huub

2018-02-01

The fingers of the human hand cannot be controlled fully independently. This phenomenon may have a neurological as well as a mechanical basis. Despite previous studies, the neuromechanics of finger movements are not fully understood. The aims of this study were (1) to assess the activation and coactivation patterns of finger specific flexor and extensor muscle regions during instructed single finger flexion and (2) to determine the relationship between enslaved finger movements and respective finger muscle activation. In 9 healthy subjects (age 22-29), muscle activation was assessed during single finger flexion using a 90 surface electromyography electrode grid placed over the flexor digitorum superficialis (FDS) and the extensor digitorum (ED). We found (1) no significant differences in muscle activation timing between fingers, (2) considerable muscle activity in flexor and extensor regions associated with the non-instructed fingers and (3) no correlation between the muscle activations and corresponding movement of non-instructed fingers. A clear disparity was found between the movement pattern of the non-instructed fingers and the activity pattern of the corresponding muscle regions. This suggests that mechanical factors, such as intertendinous and myofascial connections, may also affect finger movement independency and need to be taken into consideration when studying finger movement. Copyright © 2017 Elsevier Ltd. All rights reserved.

Experiment K-7-33: Functional Neuromuscular Adaptation to Spaceflight

NASA Technical Reports Server (NTRS)

Edgerton, V. R.; Bodine-Fowler, S.; Hodgson, J. A.; Roy, R. R.; Kozlovskaya, I. B.

1994-01-01

The following data were collected from two Rhesus monkeys (782 and 2483) that were flown aboard a 14-day biosatellite mission (COSMOS 2044). The proposed study was designed to determine the effects of the absence of weight support on flexor and extensor muscles of the hindlimb. These effects were assessed morphologically and biochemically from muscle biopsies taken from a slow extensor, the soleus; a fast extensor, the medial gastrocnemius; and a fast flexor, the tibialis anterior. A second objective of this study was to determine the relative importance of activity (as determined by intramuscular electromyography, and force (as determined by joint torque) on the adaptation of muscle.

Humeral external rotation handling by using the Bobath concept approach affects trunk extensor muscles electromyography in children with cerebral palsy.

PubMed

Grazziotin Dos Santos, C; Pagnussat, Aline S; Simon, A S; Py, Rodrigo; Pinho, Alexandre Severo do; Wagner, Mário B

2014-10-20

This study aimed to investigate the electromyographic activity of cervical and trunk extensors muscles in children with cerebral palsy during two handlings according to the Bobath concept. A crossover trial involving 40 spastic diplegic children was conducted. Electromyography (EMG) was used to measure muscular activity at sitting position (SP), during shoulder internal rotation (IR) and shoulder external rotation (ER) handlings, which were performed using the elbow joint as key point of control. Muscle recordings were performed at the fourth cervical (C4) and at the tenth thoracic (T10) vertebral levels. The Gross Motor Function Classification System (GMFCS) was used to assess whether muscle activity would vary according to different levels of severity. Humeral ER handling induced an increase on EMG signal of trunk extensor muscles at the C4 (P=0.007) and T10 (P<0.001) vertebral levels. No significant effects were observed between SP and humeral IR handling at C4 level; However at T10 region, humeral IR handling induced an increase of EMG signal (P=0.019). Humeral ER resulted in an increase of EMG signal at both levels, suggesting increase of extensor muscle activation. Furthermore, the humeral ER handling caused different responses on EMG signal at T10 vertebra level, according to the GMFCS classification (P=0.017). In summary, an increase of EMG signal was observed during ER handling in both evaluated levels, suggesting an increase of muscle activation. These results indicate that humeral ER handling can be used for diplegic CP children rehabilitation to facilitate cervical and trunk extensor muscles activity in a GMFCS level-dependent manner. Copyright © 2014 Elsevier Ltd. All rights reserved.

Exploring the Role of PGC-1α in Defining Nuclear Organisation in Skeletal Muscle Fibres.

PubMed

Ross, Jacob A; Pearson, Adam; Levy, Yotam; Cardel, Bettina; Handschin, Christoph; Ochala, Julien

2017-06-01

Muscle fibres are multinucleated cells, with each nucleus controlling the protein synthesis in a finite volume of cytoplasm termed the myonuclear domain (MND). What determines MND size remains unclear. In the present study, we aimed to test the hypothesis that the level of expression of the transcriptional coactivator PGC-1α and subsequent activation of the mitochondrial biogenesis are major contributors. Hence, we used two transgenic mouse models with varying expression of PGC-1α in skeletal muscles. We isolated myofibres from the fast twitch extensor digitorum longus (EDL) and slow twitch diaphragm muscles. We then membrane-permeabilised them and analysed the 3D spatial arrangements of myonuclei. In EDL muscles, when PGC-1α is over-expressed, MND volume decreases; whereas, when PGC-1α is lacking, no change occurs. In the diaphragm, no clear difference was noted. This indicates that PGC-1α and the related mitochondrial biogenesis programme are determinants of MND size. PGC-1α may facilitate the addition of new myonuclei in order to reach MND volumes that can support an increased mitochondrial density. J. Cell. Physiol. 232: 1270-1274, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

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.

Tubular system volume changes in twitch fibres from toad and rat skeletal muscle assessed by confocal microscopy

PubMed Central

Launikonis, Bradley S; Stephenson, D George

2002-01-01

The volume of the extracellular compartment (tubular system) within intact muscle fibres from cane toad and rat was measured under various conditions using confocal microscopy. Under physiological conditions at rest, the fractional volume of the tubular system (t-sysVol) was 1.38 ± 0.09 % (n = 17), 1.41 ± 0.09 % (n = 12) and 0.83 ± 0.07 % (n = 12) of the total fibre volume in the twitch fibres from toad iliofibularis muscle, rat extensor digitorum longus muscle and rat soleus muscle, respectively. In toad muscle fibres, the t-sysVol decreased by 30 % when the tubular system was fully depolarized and decreased by 15 % when membrane cholesterol was depleted from the tubular system with methyl-β-cyclodextrin but did not change as the sarcomere length was changed from 1.93 to 3.30 μm. There was also an increase by 30 % and a decrease by 25 % in t-sysVol when toad fibres were equilibrated in solutions that were 2.5-fold hypertonic and 50 % hypotonic, respectively. When the changes in total fibre volume were taken into consideration, the t-sysVol expressed as a percentage of the isotonic fibre volume did actually decrease as tonicity increased, revealing that the tubular system in intact fibres cannot be compressed below 0.9 % of the isotonic fibre volume. The results can be explained in terms of forces acting at the level of the tubular wall. These observations have important physiological implications showing that the tubular system is a dynamic membrane structure capable of changing its volume in response to the membrane potential, cholesterol depletion and osmotic stress but not when the sarcomere length is changed in resting muscle. PMID:11790823

Life-long calorie restriction in Fischer 344 rats attenuates age-related loss in skeletal muscle-specific force and reduces extracellular space.

PubMed

Payne, Anthony M; Dodd, Stephen L; Leeuwenburgh, Christiaan

2003-12-01

The decline in muscle function is associated with an age-related decrease in muscle mass and an age-related decline in strength. However, decreased strength is not solely due to decreased muscle mass. The age-related decline in muscle-specific force (force/muscle cross-sectional area), a measure of intrinsic muscle function, also contributes to age-related strength decline, and the mechanisms by which this occurs are only partially known. Moreover, changes in the extracellular space could have a profound effect on skeletal muscle function. Life-long calorie restriction in rodents has shown to be a powerful anti-aging intervention. In this study, we examine whether calorie restriction is able to attenuate the loss of muscle function and elevations in extracellular space associated with aging. We hypothesize that calorie restriction attenuates the age-associated decline in specific force and increases in extracellular space. Measurements of in vitro contractile properties of the extensor digitorum longus (type II) and soleus (type I) muscles from 12-mo and 26- to 28-mo-old ad libitum-fed, as well as 27- to 28-mo-old life-long calorie-restricted male Fischer 344 rats, were performed. We found that calorie restriction attenuated the age-associated decline in muscle mass-to-body mass ratio (mg/g) and strength-to-body mass ratio (N/kg) in the extensor digitorum longus muscle (P < 0.05) but not in the soleus muscle (P > 0.05). Importantly, muscle-specific force (N/cm2) in the extensor digitorum longus, but not in the soleus muscle, of the old calorie-restricted rats was equal to that of the young 12-mo-old animals. Moreover, the age-associated increase in extracellular space was reduced in the fast-twitch extensor digitorum longus muscle (P < 0.05) but not in the soleus muscle with calorie restriction. We also found a significant correlation between the extracellular space and the muscle-specific force in the extensor digitorum longus (r = -0.58; P < 0.05) but not in the soleus muscle (r = -0.38; P > 0.05). Hence, this study shows a loss of muscle function with age and suggests that long-term calorie restriction is an effective intervention against the loss of muscle function with age.

Influences of the extensor portion of the gluteus maximus muscle on pelvic tilt before and after the performance of a fatigue protocol.

PubMed

Alvim, Felipe C; Peixoto, Jennifer G; Vicente, Eduardo J D; Chagas, Paula S C; Fonseca, Diogo S

2010-01-01

There is a lack of data in the literature for determining the influences of the extensor portion of the gluteus maximus muscle on pelvic tilting and, thus, on lumbar stability. To assess the influences of the extensor portion of the gluteus maximus muscle on pelvic tilt. Ten healthy young subjects were recruited, with a body mass index (BMI) below 24.9 kg/m(2) and leg length discrepancy below 1 cm. The BMI, pelvic perimeter and lower-limb lengths were assessed and, subsequently, the degrees of hemi-pelvic tilt and asymmetry between them were analyzed using lateral view photographs of the subjects in a standing position, using SAPO (Software for Postural Assessment). Next, fatigue was induced in the extensor portion of the gluteus maximus muscle on the dominant side, and after that the hemi-pelvic tilt and the asymmetry between the hemi-pelvises were reassessed. The Pearson r and Student t tests were conducted at the significance level of alpha=0.05. There were no significant correlations between the confounding variables and asymmetry of the hemi-pelvic angles. There were significant changes in the hemi-pelvic angle of the dominant side (t=3.760; p=0.004). Fatigue in the extensor portion of the gluteus maximus muscle can generate increases in the tilt angle of the ipsilateral pelvis.

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.

Comparative anatomy of the cheek muscles within the Centromochlinae subfamily (Ostariophysi, Siluriformes, Auchenipteridae).

PubMed

Sarmento-Soares, Luisa Maria; Porto, Marcovan

2006-02-01

Glanidium melanopterum Miranda Ribeiro, a typical representative of the subfamily Centromochlinae (Siluriformes: Auchenipteridae), is herein described myologically and compared to other representative species within the group, Glanidium ribeiroi, G. leopardum, Tatia neivai, T. intermedia, T. creutzbergi, Centromochlus heckelii, and C. existimatus. The structure of seven pairs of striated cephalic muscles was compared anatomically: adductor mandibulae, levator arcus palatini, dilatator operculi, adductor arcus palatini, extensor tentaculi, retractor tentaculi, and levator operculi. We observed broad adductor mandibulae muscles in both Glanidium and Tatia, catfishes with depressed heads and smaller eyes. Similarities between muscles were observed: the presence of a large aponeurotic insertion for the levator arcus palatini muscle; an adductor arcus palatini muscle whose origin spread over the orbitosphenoid, pterosphenoid, and parasphenoid; and the extensor tentaculi muscle broadly attached to the autopalatine. There is no retractor tentaculi muscle in either the Glanidium or Tatia species. On the other hand, in Centromochlus, with forms having large eyes and the tallest head, the adductor mandibulae muscles are slim; there is a thin aponeurotic or muscular insertion for the levator arcus palatini muscle; the adductor arcus palatini muscle originates from a single osseous process, forming a keel on the parasphenoid; the extensor tentaculi muscle is loosely attached to the autopalatine, permitting exclusive rotating and sliding movements between this bone and the maxillary. The retractor tentaculi muscle is connected to the maxilla through a single tendon, so that both extensor and retractor tentaculi muscles contribute to a wide array of movements of the maxillary barbels. A discussion on the differences in autopalatine-maxillary movements among the analyzed groups is given. (c) 2005 Wiley-Liss, Inc.

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.

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.

Relationship between power-duration parameters and mechanical and anthropometric properties of the thigh in elite cyclists.

PubMed

Kordi, Mehdi; Menzies, Campbell; Parker Simpson, Len

2018-03-01

The curvature constant (W') and asymptote (critical power; CP) of the power-duration relationship are important parameters for explaining cycling performance. Short-duration endurance cycling events rely more heavily on the W'; however, the full mechanistic underpinning of this parameter is yet to be determined. Evidence suggests both muscle volume and muscle strength may contribute to the magnitude of W'. Therefore, the present study investigated the relationship between power-duration parameters (CP and W') and (1) anthropometric and (2) mechanical properties of thigh muscles in a sample of elite cyclists. Eleven elite male cyclists had gross thigh volume (T VOL ), quadriceps muscle volume (Q VOL ), vastus lateralis (VL) muscle pennation angle (PA) and VL muscle thickness (MT) measured. Additionally, maximum torque production of the knee extensors (F MAX ) was assessed. The relationship between these anthropometric and mechanical measures and both the CP and W' were determined. W' showed a very strong positive and significant relationship with F MAX (r = 0.87, p < 0.001) and a large positive and significant relationship with T VOL (r = 0.60, p =  0.05). No other anthropometric characteristics were related to the W'. The CP was not associated with any mechanical or anthropometric parameter. In addition to muscle size, the maximal evocable force of a muscle (group) appears to be linked to the magnitude of the W' in elite cyclists.

Electromyographic activity associated with spontaneous functional recovery after spinal cord injury in rats.

PubMed

Kaegi, Sibille; Schwab, Martin E; Dietz, Volker; Fouad, Karim

2002-07-01

This investigation was designed to study the spontaneous functional recovery of adult rats with incomplete spinal cord injury (SCI) at thoracic level during a time course of 2 weeks. Daily testing sessions included open field locomotor examination and electromyographic (EMG) recordings from a knee extensor (vastus lateralis, VL) and an ankle flexor muscle (tibialis anterior, TA) in the hindlimbs of treadmill walking rats. The BBB score (a locomotor score named after Basso et al., 1995, J. Neurotrauma, 12, 1-21) and various measures from EMG recordings were analysed (i.e. step cycle duration, rhythmicity of limb movements, flexor and extensor burst duration, EMG amplitude, root-mean-square, activity overlap between flexor and extensor muscles and hindlimb coupling). Directly after SCI, a marked drop in locomotor ability occurred in all rats with subsequent partial recovery over 14 days. The recovery was most pronounced during the first week. Significant changes were noted in the recovery of almost all analysed EMG measures. Within the 14 days of recovery, many of these measures approached control levels. Persistent abnormalities included a prolonged flexor burst and increased activity overlap between flexor and extensor muscles. Activity overlap between flexor and extensor muscles might be directly caused by altered descending input or by maladaptation of central pattern generating networks and/or sensory feedback.

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 unilateral knee extensor fatigue on force and balance of the contralateral limb.

PubMed

Arora, Shruti; Budden, Shawn; Byrne, Jeannette M; Behm, David G

2015-10-01

Fatigue in one limb can decrease force production in the homologous muscle as well as other muscles of the non-fatigued limb affecting balance. The objective of the study was to examine the effect of unilateral knee extensor fatigue on the non-fatigued limb's standing balance, muscle force and activation. Sixteen healthy male subjects performed pre-fatigue balance trials, warm-up exercises, maximum voluntary isometric contractions, a knee extensors fatigue protocol, and post-fatigue balance trials. The fatigue protocol consisted of sets of 15 consecutive isometric contractions of 16 s each with 4 s recovery between repetitions, which were performed at 30% peak force for the dominant knee extensor muscles. Additional sets of contractions continued until a 50% decrease in MVIC knee extensor force was observed. Pre- and post-fatigue balance assessment consisted of transition from double to single leg standing and also single leg standing trials, which were performed bilaterally and in randomized order. The peak force and F100 were significantly decreased by 44.8% (ES = 2.54) and 39.9% (ES = 0.59), respectively, for the fatigued limb post-fatigue. There were no significant changes in the non-fatigued limb's muscle force, activation, muscle onset timing or postural stability parameters. While the lack of change in non-fatigued limb force production is in agreement with some of the previous literature in this area, the lack of effect on postural measures directly contradicts earlier work. It is hypothesized that discrepancies in the duration and the intensity of the fatigue protocol may have accounted for this discrepancy.

Adaptation of skeletal muscle to spaceflight: Cosmos rhesus project. Cosmos 2044 and 2229

NASA Technical Reports Server (NTRS)

Bodine-Fowler, Sue

1994-01-01

The proposed experiments were designed to determine the effects of the absence of weight support on hindlimb muscles of the monkey: an ankle flexor (tibialis anterior, TA), two ankle extensors (medial gastrocnemius, MG and soleus, SOL), and a knee extensor (vastus lateralis, VL). These effects were assessed by examining the biochemical and morphological properties of muscle fibers obtained from biopsies in young Rhesus monkeys (3-4 Kg). Biopsies taken from ground base experiments were analyzed to determine: (1) the effects of chair restraint at 1 G on muscle properties and (2) the growth rate of flexor and extensor muscles in the Rhesus. In addition, two sets of biopsies were taken from monkeys which were in the flight pool and the four monkeys that flew on the Cosmos 2044 and 2229 biosatellite missions. Based on data collected in rats it is generally assumed that extensors atrophy to a greater extent than flexors in response to spaceflight or hindlimb suspension. Consequently, the finding that fibers in the TA (a fast flexor) of the flight monkeys atrophied, whereas fibers in the Sol (a predominantly slow extensor) and MG (a fast extensor) grew after a 14-day spaceflight (Cosmos 2044) and 12-day spaceflight (Cosmos 2229) was unexpected. In Cosmos 2044, the TA in both flight monkeys had a 21 percent decrease in fiber size, whereas the Sol and MG both had a 79 percent increase in fiber size. In Cosmos 2229, the TA in both flight monkeys showed significant atrophy, whereas the Sol and MG showed slight growth in one monkey (906) and slight atrophy in the other monkey (151).

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

Long-latency reflexes of elbow and shoulder muscles suggest reciprocal excitation of flexors, reciprocal excitation of extensors, and reciprocal inhibition between flexors and extensors

PubMed Central

Meriggi, Jenna; Parikh, Nidhi; Saad, Kenneth

2016-01-01

Postural corrections of the upper limb are required in tasks ranging from handling an umbrella in the changing wind to securing a wriggling baby. One complication in this process is the mechanical interaction between the different segments of the arm where torque applied at one joint induces motion at multiple joints. Previous studies have shown the long-latency reflexes of shoulder muscles (50–100 ms after a limb perturbation) account for these mechanical interactions by integrating information about motion of both the shoulder and elbow. It is less clear whether long-latency reflexes of elbow muscles exhibit a similar capability and what is the relation between the responses of shoulder and elbow muscles. The present study utilized joint-based loads tailored to the subjects' arm dynamics to induce well-controlled displacements of their shoulder and elbow. Our results demonstrate that the long-latency reflexes of shoulder and elbow muscles integrate motion from both joints: the shoulder and elbow flexors respond to extension at both joints, whereas the shoulder and elbow extensors respond to flexion at both joints. This general pattern accounts for the inherent flexion-extension coupling of the two joints arising from the arm's intersegmental dynamics and is consistent with spindle-based reciprocal excitation of shoulder and elbow flexors, reciprocal excitation of shoulder and elbow extensors, and across-joint inhibition between the flexors and extensors. PMID:26864766

Activity of thoracic and lumbar epaxial extensors during postural responses in the cat

NASA Technical Reports Server (NTRS)

Macpherson, J. M.; Fung, J.; Peterson, B. W. (Principal Investigator)

1998-01-01

This study examined the role of trunk extensor muscles in the thoracic and lumbar regions during postural adjustments in the freely standing cat. The epaxial extensor muscles participate in the rapid postural responses evoked by horizontal translation of the support surface. The muscles segregate into two regional groups separated by a short transition zone, according to the spatial pattern of the electromyographic (EMG) responses. The upper thoracic muscles (T5-9) respond best to posteriorly directed translations, whereas the lumbar muscles (T13 to L7) respond best to anterior translations. The transition group muscles (T10-12) respond to almost all translations. Muscles group according to vertebral level rather than muscle species. The upper thoracic muscles change little in their response with changes in stance distance (fore-hindpaw separation) and may act to stabilize the intervertebral angles of the thoracic curvature. Activity in the lumbar muscles increases along with upward rotation of the pelvis (iliac crest) as stance distance decreases. Lumbar muscles appear to stabilize the pelvis with respect to the lumbar vertebrae (L7-sacral joint). The transition zone muscles display a change in spatial tuning with stance distance, responding to many directions of translation at short distances and focusing to respond best to contralateral translations at the long stance distance.

Cervical Musculoskeletal Impairments and Temporomandibular Disorders

PubMed Central

Magee, David

2012-01-01

ABSTRACT Objectives The study of cervical muscles and their significance in the development and perpetuation of Temporomandibular Disorders has not been elucidated. Thus this project was designed to investigate the association between cervical musculoskeletal impairments and Temporomandibular Disorders. Material and Methods A sample of 154 subjects participated in this study. All subjects underwent a series of physical tests and electromyographic assessment (i.e. head and neck posture, maximal cervical muscle strength, cervical flexor and extensor muscles endurance, and cervical flexor muscle performance) to determine cervical musculoskeletal impairments. Results A strong relationship between neck disability and jaw disability was found (r = 0.82). Craniocervical posture was statistically different between patients with myogenous Temporomandibular Disorders (TMD) and healthy subjects. However, the difference was too small (3.3º) to be considered clinically relevant. Maximal cervical flexor muscle strength was not statistically or clinically different between patients with TMD and healthy subjects. No statistically significant differences were found in electromyographic activity of the sternocleidomastoid or the anterior scalene muscles in patients with TMD when compared to healthy subjects while executing the craniocervical flexion test (P = 0.07). However, clinically important effect sizes (0.42 - 0.82) were found. Subjects with TMD presented with reduced cervical flexor as well as extensor muscle endurance while performing the flexor and extensor muscle endurance tests when compared to healthy individuals. Conclusions Subjects with Temporomandibular Disorders presented with impairments of the cervical flexors and extensors muscles. These results could help guide clinicians in the assessment and prescription of more effective interventions for individuals with Temporomandibular Disorders. PMID:24422022

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.

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.

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.

Sex comparisons of non-local muscle fatigue in human elbow flexors and knee extensors

PubMed Central

Ye, Xin; Beck, Travis W.; Wages, Nathan P.; Carr, Joshua C.

2018-01-01

Objectives: To examine non-local muscle fatigue (NLMF) in both contralateral homologous and non-related heterogonous muscles for both sexes. Methods: Ten men and nine women participated in this study. After the familiarization visit, subjects completed four separate randomly sequenced experimental visits, during which the fatiguing interventions (six sets of 30-second maximal isometric contractions) were performed on either their right elbow flexors or knee extensors. Before (Pre-) and after (Post-) the fatiguing interventions, the isometric strength and the corresponding surface electromyographic (EMG) amplitude were measured for the non-exercised left elbow flexors or knee extensors. Results: For the non-exercised elbow flexors, the isometric strength decreased for both sexes (sex combined mean±SE: Pre vs. Post=339.67±18.02 N vs. 314.41±16.37 N; p<0.001). For the non-exercised knee extensors, there is a time ´ sex interaction (p=0.025), showing a decreased isometric knee extension strength for men (Pre vs. Post =845.02±66.26 N vs. 817.39±67.64 N; p=0.019), but not for women. Conclusions: The presence of NMLF can be affected by factors such as sex and muscle being tested. Women are less likely to demonstrate NLMF in lower body muscle groups. PMID:29504584

Age-Related Locomotion Characteristics in Association with Balance Function in Young, Middle-Aged, and Older Adults.

PubMed

Lee, Hwang-Jae; Chang, Won Hyuk; Hwang, Sun Hee; Choi, Byung-Ok; Ryu, Gyu-Ha; Kim, Yun-Hee

2017-04-01

The purpose of this study was to examine age-related gait characteristics and their associations with balance function in older adults. A total of 51 adult volunteers participated. All subjects underwent locomotion analysis using a 3D motion analysis and 12-channel dynamic electromyography system. Dynamic balance function was assessed by the Berg Balance Scale. Older adults showed a higher level of muscle activation than young adults, and there were significant positive correlations between increased age and activation of the trunk and thigh muscles in the stance and swing phase of the gait cycle. In particular, back extensor muscle activity was mostly correlated with the dynamic balance in older adults. Thus, back extensor muscle activity in walking may provide a clue for higher falling risk in older adults. This study demonstrates that the back extensor muscles play very important roles with potential for rehabilitation training to improve balance and gait in older adults.

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.

Transposition of branches of radial nerve innervating supinator to posterior interosseous nerve for functional reconstruction of finger and thumb extension in 4 patients with middle and lower trunk root avulsion injuries of brachial plexus.

PubMed

Wu, Xia; Cong, Xiao-Bing; Huang, Qi-Shun; Ai, Fang-Xin; Liu, Yu-Tian; Lu, Xiao-Cheng; Li, Jin; Weng, Yu-Xiong; Chen, Zhen-Bing

2017-12-01

This study aimed to investigate the reconstruction of the thumb and finger extension function in patients with middle and lower trunk root avulsion injuries of the brachial plexus. From April 2010 to January 2015, we enrolled in this study 4 patients diagnosed with middle and lower trunk root avulsion injuries of the brachial plexus via imaging tests, electrophysiological examinations, and clinical confirmation. Muscular branches of the radial nerve, which innervate the supinator in the forearm, were transposed to the posterior interosseous nerve to reconstruct the thumb and finger extension function. Electrophysiological findings and muscle strength of the extensor pollicis longus and extensor digitorum communis, as well as the distance between the thumb tip and index finger tip, were monitored. All patients were followed up for 24 to 30 months, with an average of 27.5 months. Motor unit potentials (MUP) of the extensor digitorum communis appeared at an average of 3.8 months, while MUP of the extensor pollicis longus appeared at an average of 7 months. Compound muscle action potential (CMAP) appeared at an average of 9 months in the extensor digitorum communis, and 12 months in the extensor pollicis longus. Furthermore, the muscle strength of the extensor pollicis longus and extensor digitorum communis both reached grade III at 21 months. Lastly, the average distance between the thumb tip and index finger tip was 8.8 cm at 21 months. In conclusion, for patients with middle and lower trunk injuries of the brachial plexus, transposition of the muscular branches of the radial nerve innervating the supinator to the posterior interosseous nerve for the reconstruction of thumb and finger extension function is practicable and feasible.

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.

Octopamine mediated relaxation of maintained and catch tension in locust skeletal muscle.

PubMed

Evans, P D; Siegler, M V

1982-03-01

1. The modulatory actions of an identified octopaminergic neurone (DUMETi) that projects to the extensor-tibiae muscle of the locust hind leg depend upon the frequency of stimulation of the slow motoneurone (SETi) to this muscle. 2. At low frequencies of SETi stimulation (1Hz and below) the predominant modulatory effects are increases in the amplitude and relaxation rate of twitch tension. At higher frequencies, where twitches summate but tetanus is incomplete (up to 20 Hz), the reduction of maintained tension becomes considerably more important. 3. Both octopamine application and DUMETi stimulation reduce the amount of catch tension displayed by the extensor muscle when SETi is fired in a variety of different stimulus patterns. The extensor-tibiae muscle is itself 'pattern sensitive' since is shows a 'positive spacing effect' when SETi is stimulated at an average frequency of 1 Hz. 4. It is suggested that a primary function of DUMETi is to change the response of the muscle from one that favours maintenance of posture to one that favours rapid changes in joint position or force, such as might occur during locomotion.

Octopamine mediated relaxation of maintained and catch tension in locust skeletal muscle.

PubMed Central

Evans, P D; Siegler, M V

1982-01-01

1. The modulatory actions of an identified octopaminergic neurone (DUMETi) that projects to the extensor-tibiae muscle of the locust hind leg depend upon the frequency of stimulation of the slow motoneurone (SETi) to this muscle. 2. At low frequencies of SETi stimulation (1Hz and below) the predominant modulatory effects are increases in the amplitude and relaxation rate of twitch tension. At higher frequencies, where twitches summate but tetanus is incomplete (up to 20 Hz), the reduction of maintained tension becomes considerably more important. 3. Both octopamine application and DUMETi stimulation reduce the amount of catch tension displayed by the extensor muscle when SETi is fired in a variety of different stimulus patterns. The extensor-tibiae muscle is itself 'pattern sensitive' since is shows a 'positive spacing effect' when SETi is stimulated at an average frequency of 1 Hz. 4. It is suggested that a primary function of DUMETi is to change the response of the muscle from one that favours maintenance of posture to one that favours rapid changes in joint position or force, such as might occur during locomotion. PMID:6808122

Wrist muscle activity of khatrah approach in Mameluke technique using traditional bow archery

NASA Astrophysics Data System (ADS)

Ariffin, Muhammad Shahimi; Rambely, Azmin Sham; Ariff, Noratiqah Mohd

2018-04-01

An investigation of khatrah technique in archery was carried out. An electromyography (EMG) experiment was conducted towards six wrist muscles which are flexor carpi radialis, extensor carpi ulnaris and extensor digitorum communis for both arms. The maximum voluntary contraction (MVC) and activity data were recorded. The bow arm produced a higher muscle force compared to draw arm muscles during release phase. However, the muscle forces produced by bow arm had a consistency in term of pattern throughout the phases. In conclusion, the forces generated by the professional archer produced a force benchmark at the wrist joint to alleviate the risk of injury.

Isokinetic Evaluation of the Hip Flexor and Extensor Muscles: A Systematic Review.

PubMed

Zapparoli, Fabricio Yuri; Riberto, Marcelo

2017-11-01

Isokinetic dynamometry testing is a safe and reliable method accepted as the "gold standard" in the evaluation of muscle strength in the open kinetic chain. Isokinetic hip examinations face problems in the standardization of the position of the equipment axis, in the individual being examined, and in the adjustment of the lever arm and in stabilization strategies for the patients during the tests. Identification of the methodologic procedures with best reproducibility is also needed. To review the literature to evaluate the parameters used for the isokinetic evaluation of the hip flexor and extensor muscles and its reproducibility. This is a systematic literature review of the Cochrane, LILACS, PEDro, PubMed, and SciELO databases. The inclusion criteria were articles on the evaluation of hip flexor and/or extensor muscular strength with an isokinetic dynamometer and articles that analyzed the ICC or Pearson's reproducibility. The information extracted was positioning of the patient; positioning of the dynamometer axis; positioning of the lever arm; angular speed; sample size, pathology; type of contraction; and ICC and Pearson's results. 204 articles were found, from which 14 were selected that evaluated hip flexor and extensor muscles, involving 550 individuals who were submitted to an isokinetic hip evaluation. Five articles obtained the best result in reproducibility and had their methodology analyzed. To obtain better reproducibility of the isokinetic evaluation of the hip flexor and extensor muscles, the following recommendations must be followed: the individual must be positioned in the supine position and the dynamometer axis must be aligned with the greater trochanter of the femur. The positioning of the lever arm must be in the most distal region of the thigh possible. The angular speed used to analyze torque peak and muscle work was 60°/s, and to evaluate the muscle power it was 180°/s, with concentric and eccentric contractions being analyzed.

Comparative proteomic profiling of soleus, extensor digitorum longus, flexor digitorum brevis and interosseus muscles from the mdx mouse model of Duchenne muscular dystrophy.

PubMed

Carberry, Steven; Brinkmeier, Heinrich; Zhang, Yaxin; Winkler, Claudia K; Ohlendieck, Kay

2013-09-01

Duchenne muscular dystrophy is due to genetic abnormalities in the dystrophin gene and represents one of the most frequent genetic childhood diseases. In the X-linked muscular dystrophy (mdx) mouse model of dystrophinopathy, different subtypes of skeletal muscles are affected to a varying degree albeit the same single base substitution within exon 23 of the dystrophin gene. Thus, to determine potential muscle subtype-specific differences in secondary alterations due to a deficiency in dystrophin, in this study, we carried out a comparative histological and proteomic survey of mdx muscles. We intentionally included the skeletal muscles that are often used for studying the pathomechanism of muscular dystrophy. Histological examinations revealed a significantly higher degree of central nucleation in the soleus and extensor digitorum longus muscles compared with the flexor digitorum brevis and interosseus muscles. Muscular hypertrophy of 20-25% was likewise only observed in the soleus and extensor digitorum longus muscles from mdx mice, but not in the flexor digitorum brevis and interosseus muscles. For proteomic analysis, muscle protein extracts were separated by fluorescence two-dimensional (2D) gel electrophoresis. Proteins with a significant change in their expression were identified by mass spectrometry. Proteomic profiling established an altered abundance of 24, 17, 19 and 5 protein species in the dystrophin-deficient soleus, extensor digitorum longus, flexor digitorum brevis and interosseus muscle, respectively. The key proteomic findings were verified by immunoblot analysis. The identified proteins are involved in the contraction-relaxation cycle, metabolite transport, muscle metabolism and the cellular stress response. Thus, histological and proteomic profiling of muscle subtypes from mdx mice indicated that distinct skeletal muscles are differentially affected by the loss of the membrane cytoskeletal protein, dystrophin. Varying degrees of perturbed protein expression patterns in the muscle subtypes from mdx mice may be due to dissimilar downstream events, including differences in muscle structure or compensatory mechanisms that counteract pathophysiological processes. The interosseus muscle from mdx mice possibly represents a naturally protected phenotype.

Comparative proteomic profiling of soleus, extensor digitorum longus, flexor digitorum brevis and interosseus muscles from the mdx mouse model of Duchenne muscular dystrophy

PubMed Central

CARBERRY, STEVEN; BRINKMEIER, HEINRICH; ZHANG, YAXIN; WINKLER, CLAUDIA K.; OHLENDIECK, KAY

2013-01-01

Duchenne muscular dystrophy is due to genetic abnormalities in the dystrophin gene and represents one of the most frequent genetic childhood diseases. In the X-linked muscular dystrophy (mdx) mouse model of dystrophinopathy, different subtypes of skeletal muscles are affected to a varying degree albeit the same single base substitution within exon 23 of the dystrophin gene. Thus, to determine potential muscle subtype-specific differences in secondary alterations due to a deficiency in dystrophin, in this study, we carried out a comparative histological and proteomic survey of mdx muscles. We intentionally included the skeletal muscles that are often used for studying the pathomechanism of muscular dystrophy. Histological examinations revealed a significantly higher degree of central nucleation in the soleus and extensor digitorum longus muscles compared with the flexor digitorum brevis and interosseus muscles. Muscular hypertrophy of 20–25% was likewise only observed in the soleus and extensor digitorum longus muscles from mdx mice, but not in the flexor digitorum brevis and interosseus muscles. For proteomic analysis, muscle protein extracts were separated by fluorescence two-dimensional (2D) gel electrophoresis. Proteins with a significant change in their expression were identified by mass spectrometry. Proteomic profiling established an altered abundance of 24, 17, 19 and 5 protein species in the dystrophin-deficient soleus, extensor digitorum longus, flexor digitorum brevis and interosseus muscle, respectively. The key proteomic findings were verified by immunoblot analysis. The identified proteins are involved in the contraction-relaxation cycle, metabolite transport, muscle metabolism and the cellular stress response. Thus, histological and proteomic profiling of muscle subtypes from mdx mice indicated that distinct skeletal muscles are differentially affected by the loss of the membrane cytoskeletal protein, dystrophin. Varying degrees of perturbed protein expression patterns in the muscle subtypes from mdx mice may be due to dissimilar downstream events, including differences in muscle structure or compensatory mechanisms that counteract pathophysiological processes. The interosseus muscle from mdx mice possibly represents a naturally protected phenotype. PMID:23828267

The effects of Kinesio Taping on the trajectory of the forelimb and the muscle activity of the Musculus brachiocephalicus and the Musculus extensor carpi radialis in horses

PubMed Central

Zellner, Antonia; Bockstahler, Barbara; Peham, Christian

2017-01-01

Background information The present study aimed to investigate the effects of Kinesio Taping on the trajectory of the forelimb and the muscle activity of the M. brachiocephalicus and the M. extensor carpi radialis in horses. 19 horses and ponies of different breeds (body weight: 496±117 kg), gender (8 mares, 10 geldings and 3 stallions) and ages (14.9±6.9 years old) were analysed without Kinesio Tape (“no tape”), with Kinesio Tape (muscle facilitation application on both muscles of both sides, “with tape”) and immediately after Kinesio Taping (“post tape”) through kinematic motion analysis and surface electromyography on a treadmill at the walk (speed: 1.5±0.1 m/s) and trot (speed: 3.1±0.3 m/s). Results The results of the surface electromyography (maximum muscle activity at the walk and trot) and the kinematic motion analysis (maximum stride length and maximum height of the forelimbs flight arc at the walk and trot) showed that there were no significant differences between "no tape", "with tape" and "post tape". Conclusion To sum up, Kinesio Taping on the M. brachiocephalicus and the M. extensor carpi radialis does not affect (in a positive or negative manner) the trajectory of the forelimb or the muscle activity of the M. brachiocephalicus and the M. extensor carpi radialis in horses. PMID:29166657

Differences in muscle activity during hand-dexterity tasks between women with arthritis and a healthy reference group.

PubMed

Brorsson, Sofia; Nilsdotter, Anna; Thorstensson, Carina; Bremander, Ann

2014-05-15

Impaired hand function is common in patients with arthritis and it affects performance of daily activities; thus, hand exercises are recommended. There is little information on the extent to which the disease affects activation of the flexor and extensor muscles during these hand-dexterity tasks. The purpose of this study was to compare muscle activation during such tasks in subjects with arthritis and in a healthy reference group. Muscle activation was measured in m. extensor digitorium communis (EDC) and in m. flexor carpi radialis (FCR) with surface electromyography (EMG) in women with rheumatoid arthritis (RA, n = 20), hand osteoarthritis (HOA, n = 16) and in a healthy reference group (n = 20) during the performance of four daily activity tasks and four hand exercises. Maximal voluntary isometric contraction (MVIC) was measured to enable intermuscular comparisons, and muscle activation is presented as %MVIC. The arthritis group used a higher %MVIC than the reference group in both FCR and EDC when cutting with a pair of scissors, pulling up a zipper and-for the EDC-also when writing with a pen and using a key (p < 0.02). The exercise "rolling dough with flat hands" required the lowest %MVIC and may be less effective in improving muscle strength. Women with arthritis tend to use higher levels of muscle activation in daily tasks than healthy women, and wrist extensors and flexors appear to be equally affected. It is important that hand training programs reflect real-life situations and focus also on extensor strength.

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.

Acute Effects of Different Agonist and Antagonist Stretching Arrangements on Static and Dynamic Range of Motion.

PubMed

Amiri-Khorasani, Mohammadtaghi; Kellis, Eleftherios

2015-12-01

Traditionally, stretching exercises are considered as basic components of warm up aiming to prepare the musculoskeletal system for performance and to prevent injuries. The purpose of this study was to examine the effects of different agonist and antagonist stretching arrangements within a pre-exercise warm-up on hip static (SROM) and dynamic range of motion (DROM). Sixty trained male subjects (Mean ± SD: height, 177.38 ± 6.92 cm; body mass, 68.4 ± 10.22 kg; age, 21.52 ± 1.17 years) volunteered to participate in this study. SROM was measured by V-sit test and DROM captured by a motion analysis system before and after (i) static stretching for both hip flexor and extensor muscles (SFSE), (ii) dynamic stretching for both hip flexor and extensor muscles (DFDE), (iii) static stretching for the hip flexors and dynamic stretching for hip extensors (SFDE), and (iv) dynamic stretching for the hip flexors and static stretching for hip extensors (DFSE). DFSE showed a significantly higher increase in DROM and SROM than the remainder of the stretching protocols (P < 0.05). There were significant differences between DFDE with SFSE and SFDE (P < 0.05) and SFSE showed significant increase as compared to SFDE (P < 0.05). In conclusion, DFSE is probably the best stretching arrangement due to producing more post activation potentiation on agonist muscles and less muscle stiffness in antagonist muscles.

Acute effects of static and dynamic stretching on leg flexor and extensor isokinetic strength in elite women athletes.

PubMed

Sekir, U; Arabaci, R; Akova, B; Kadagan, S M

2010-04-01

The aim of this study was to explore the effects of static and dynamic stretching of the leg flexors and extensors on concentric and eccentric peak torque (PT) and electromyography (EMG) amplitude of the leg extensors and flexors in women athletes. Ten elite women athletes completed the following intervention protocol in a randomized order on separate days: (a) non-stretching (control), (b) static stretching, and (c) dynamic stretching. Stretched muscles were the quadriceps and hamstring muscles. Before and after the stretching or control intervention, concentric and eccentric isokinetic PT and EMG activity of the leg extensors and flexors were measured at 60 and 180 degrees/s. Concentric and eccentric quadriceps and hamstring muscle strength at both test speeds displayed a significant decrease following static stretching (P<0.01-0.001). In contrast, a significant increase was observed after dynamic stretching for these strength parameters (P<0.05-0.001). Parallel to this, normalized EMG amplitude parameters exhibited significant decreases following static (P<0.05-0.001) and significant increases following dynamic stretching (P<0.05-0.001) during quadriceps and hamstring muscle actions at both concentric and eccentric testing modes. Our findings suggest that dynamic stretching, as opposed to static or no stretching, may be an effective technique for enhancing muscle performance during the pre-competition warm-up routine in elite women athletes.

Relationship between functional electrical stimulation duty cycle and fatigue in wrist extensor muscles of patients with hemiparesis.

PubMed

Packman-Braun, R

1988-01-01

The purpose of this study was to investigate, in a sample of patients with hemiparesis secondary to cerebrovascular accident, the relationship between the ratio of stimulus on time to off time and muscle fatigue using a commercial electrical stimulation unit. An experimental model was used to test the hypothesis that the smaller the stimulus off time relative to stimulus on time, the greater will be the muscle fatigue over time. The wrist extensor muscles of 18 patients with hemiparesis were stimulated electrically, and isometric force output was recorded continuously using an adapted strain gauge-recorder apparatus. For each testing session, peak on time of the electrical stimulus was set at 5 seconds, and off time was set at 5, 15, or 25 seconds. Six randomly assigned treatment groups participated in three separate treatment sessions in a different order at 48-hour intervals. Treatment sessions were continued either until wrist extensor muscle force output decreased to 50% of its initial value or for a maximum of 30 minutes. Data analysis revealed that significant differences in muscle tension developed among all duty cycles (p less than .01). Duty-cycle ratios of 1:1, 1:3, and 1:5 were shown to be progressively less fatiguing. Within the limits of this investigation, the 1:5 duty-cycle ratio was determined to be the best suited for initial use in programs of prolonged stimulation to the wrist extensor muscles of patients with hemiparesis. The hypothesis was accepted that the smaller the stimulus off time (rest interval) with respect to the stimulus on time, the greater will be the muscle fatigue over time.

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.

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.

Neck Flexor and Extensor Muscle Endurance in Subclinical Neck Pain: Intrarater Reliability, Standard Error of Measurement, Minimal Detectable Change, and Comparison With Asymptomatic Participants in a University Student Population.

PubMed

Lourenço, Ana S; Lameiras, Carina; Silva, Anabela G

2016-01-01

The aims of this study were to assess intrarater reliability and to calculate the standard error of measurement (SEM) and minimal detectable change (MDC) for deep neck flexor and neck extensor muscle endurance tests, and compare the results between individuals with and without subclinical neck pain. Participants were students of the University of Aveiro reporting subclinical neck pain and asymptomatic participants matched for sex and age to the neck pain group. Data on endurance capacity of the deep neck flexors and neck extensors were collected by a blinded assessor using the deep neck flexor endurance test and the extensor endurance test, respectively. Intraclass correlation coefficients (ICCs), SEM, and MDC were calculated for measurements taken within a session by the same assessor. Differences between groups for endurance capacity were investigated using a Mann-Whitney U test. The deep neck flexor endurance test (ICC = 0.71; SEM = 6.91 seconds; MDC = 19.15 seconds) and neck extensor endurance test (ICC = 0.73; SEM = 9.84 minutes; MDC = 2.34 minutes) are reliable. No significant differences were found between participants with and without neck pain for both tests of muscle endurance (P > .05). The endurance capacity of the deep neck flexors and neck extensors can be reliably measured in participants with subclinical neck pain. However, the wide SEM and MDC might limit the sensitivity of these tests. Copyright © 2016. Published by Elsevier Inc.

Computer simulations of neural mechanisms explaining upper and lower limb excitatory neural coupling

PubMed Central

2010-01-01

Background When humans perform rhythmic upper and lower limb locomotor-like movements, there is an excitatory effect of upper limb exertion on lower limb muscle recruitment. To investigate potential neural mechanisms for this behavioral observation, we developed computer simulations modeling interlimb neural pathways among central pattern generators. We hypothesized that enhancement of muscle recruitment from interlimb spinal mechanisms was not sufficient to explain muscle enhancement levels observed in experimental data. Methods We used Matsuoka oscillators for the central pattern generators (CPG) and determined parameters that enhanced amplitudes of rhythmic steady state bursts. Potential mechanisms for output enhancement were excitatory and inhibitory sensory feedback gains, excitatory and inhibitory interlimb coupling gains, and coupling geometry. We first simulated the simplest case, a single CPG, and then expanded the model to have two CPGs and lastly four CPGs. In the two and four CPG models, the lower limb CPGs did not receive supraspinal input such that the only mechanisms available for enhancing output were interlimb coupling gains and sensory feedback gains. Results In a two-CPG model with inhibitory sensory feedback gains, only excitatory gains of ipsilateral flexor-extensor/extensor-flexor coupling produced reciprocal upper-lower limb bursts and enhanced output up to 26%. In a two-CPG model with excitatory sensory feedback gains, excitatory gains of contralateral flexor-flexor/extensor-extensor coupling produced reciprocal upper-lower limb bursts and enhanced output up to 100%. However, within a given excitatory sensory feedback gain, enhancement due to excitatory interlimb gains could only reach levels up to 20%. Interconnecting four CPGs to have ipsilateral flexor-extensor/extensor-flexor coupling, contralateral flexor-flexor/extensor-extensor coupling, and bilateral flexor-extensor/extensor-flexor coupling could enhance motor output up to 32%. Enhancement observed in experimental data exceeded 32%. Enhancement within this symmetrical four-CPG neural architecture was more sensitive to relatively small interlimb coupling gains. Excitatory sensory feedback gains could produce greater output amplitudes, but larger gains were required for entrainment compared to inhibitory sensory feedback gains. Conclusions Based on these simulations, symmetrical interlimb coupling can account for much, but not all of the excitatory neural coupling between upper and lower limbs during rhythmic locomotor-like movements. PMID:21143960

The Fate of the Iliopsoas Muscle in Long-term Follow-up After Open Reduction With a Medial Approach in Developmental Dysplasia of the Hip. Part 2: Isokinetic Muscle Strength Evaluation.

PubMed

Yilmaz, Serdar; Aksahin, Ertugrul; Ersoz, Murat; Bicimoglu, Ali

2017-09-01

The impact on long-term weakness of hip flexion of complete iliopsoas tenotomy during open reduction of developmental hip dysplasia with a medial approach has not yet been fully clarified. The purpose of this study was to investigate the isokinetic muscle strength (IMS) of hip flexor and extensor muscles in these patients and also to analyze the effect of spontaneous reattachment of the iliopsoas muscle on IMS measurements. The study included 20 patients. Earlier magnetic resonance imaging examination of all the patients revealed spontaneous reattachment of the iliopsoas in 18 (90%) patients. IMS measurements were performed at 60 and 150 degrees/s. The peak torque, total work (TW), average power (AP), work fatigue, and agonist to antagonist muscle ratio of the operated and nonoperated hips were recorded separately for flexors and extensors. The effect of iliopsoas reattachment on IMS was also evaluated. The mean follow-up period was 16.65±2.16 (13 to 20) years. Total work (P=0.013) and average power (P=0.009) of the flexor muscles and work fatigue of the extensor muscles (P=0.030) of the operated hip were significantly decreased when compared with the nonoperated hips at 150 degrees/s. There was no significant difference between the flexor muscles of the operated and nonoperated hips (P<0.05) at 60 degrees/s and extensor muscles (P<0.05) at 150 degrees/s. In addition, patients without reattachment had lower IMS in the operated hips. Flexor muscle strength was decreased in the operated hip against low resistance in long-term follow-up after iliopsoas tenotomy. This may reflect that hip muscle strength was decreased after prolonged activities such as sports. However, in forceful activities flexor muscle strength was retained due to iliopsoas reattachment. On the basis of this study we thought that spontaneous reattachment of the iliopsoas tendon substantially preserves muscle strength. Nonetheless possible efforts should be made to surgically reattach the psoas tendon to preserve strength of the muscle. Therapeutic level IV.

Mobile input device type, texting style and screen size influence upper extremity and trapezius muscle activity, and cervical posture while texting.

PubMed

Kietrys, David M; Gerg, Michael J; Dropkin, Jonathan; Gold, Judith E

2015-09-01

This study aimed to determine the effects of input device type, texting style, and screen size on upper extremity and trapezius muscle activity and cervical posture during a short texting task in college students. Users of a physical keypad produced greater thumb, finger flexor, and wrist extensor muscle activity than when texting with a touch screen device of similar dimensions. Texting on either device produced greater wrist extensor muscle activity when texting with 1 hand/thumb compared with both hands/thumbs. As touch screen size increased, more participants held the device on their lap, and chose to use both thumbs less. There was also a trend for greater finger flexor, wrist extensor, and trapezius muscle activity as touch screen size increased, and for greater cervical flexion, although mean differences for cervical flexion were small. Future research can help inform whether the ergonomic stressors observed during texting are associated with musculoskeletal disorder risk. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

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

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…

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.

Neuromuscular plasticity in the locust after permanent removal of an excitatory motoneuron of the extensor tibiae muscle.

PubMed

Büschges, A; Djokaj, S; Bässler, D; Bässler, U; Rathmayer, W

2000-01-01

The capacity of the larval insect nervous system to compensate for the permanent loss of one of the two excitatory motoneurons innervating a leg muscle was investigated in the locust (Locusta migratoria). In the fourth instar, the fast extensor tibiae (FETi) motoneuron in the mesothoracic ganglion was permanently removed by photoinactivation with a helium-cadmium laser. Subsequently, the animals were allowed to develop into adulthood. When experimental animals were tested as adults after final ecdysis, fast-contracting fibers in the most proximal region of the corresponding extensor muscle, which are normally predominantly innervated by FETi only, uniformly responded to activity of the slow extensor tibiae (SETi) neuron. In adult operated animals, single pulses to SETi elicited large junctional responses in the fibers which resulted in twitch contractions of these fibers similar to the responses to FETi activity in control animals. The total number of muscle fibers, their properties as histochemically determined contractional types (fast and slow), and their distribution were not affected by photoinactivation of FETi. Possible mechanisms enabling the larval neuromuscular system to compensate for the loss of FETi through functionally similar innervation by a different motoneuron, i.e. SETi, are discussed. Copyright 2000 John Wiley & Sons, Inc.

Proximal forearm extensor muscle strain is reduced when driving nails using a shock-controlled hammer.

PubMed

Buchanan, Kimberly A; Maza, Maria; Pérez-Vázquez, Carlos E; Yen, Thomas Y; Kijowski, Richard; Liu, Fang; Radwin, Robert G

2016-10-01

Repetitive hammer use has been associated with strain and musculoskeletal injuries. This study investigated if using a shock-control hammer reduces forearm muscle strain by observing adverse physiological responses (i.e. inflammation and localized edema) after use. Three matched framing hammers were studied, including a wood-handle, steel-handle, and shock-control hammer. Fifty volunteers were randomly assigned to use one of these hammers at a fatiguing pace of one strike every second, to seat 20 nails in a wood beam. Magnetic resonance imaging was used to scan the forearm muscles for inflammation before the task, immediately after hammering, and one to two days after. Electromyogram signals were measured to estimate grip exertions and localized muscle fatigue. High-speed video was used to calculate the energy of nail strikes. While estimated grip force was similar across the three hammers, the shock-control hammer had 40% greater kinetic energy upon impact and markedly less proximal extensor muscle edema than the wood-handle and steel-handle hammers, immediately after use (p<.05). Less edema observed for the shock-control hammer suggests that isolating handle shock can mitigate strain in proximal forearm extensor muscles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimation of muscle torque in various combat sports.

PubMed

Pędzich, Wioletta; Mastalerz, Andrzej; Sadowski, Jerzy

2012-01-01

The purpose of the research was to compare muscle torque of elite combat groups. Twelve taekwondo WTF athletes, twelve taekwondo ITF athletes and nine boxers participated in the study. Measurements of muscle torques were done under static conditions on a special stand which belonged to the Department of Biomechanics. The sum of muscle torque of lower right and left extremities of relative values was significantly higher for taekwondo WTF athletes than for boxers (16%, p < 0.001 for right and 10%, p < 0.05 for left extremities) and taekwondo ITF (10%, p < 0.05 for right and 8% for left extremities). Taekwondo ITF athletes attained significantly higher absolute muscle torque values than boxers for elbow flexors (20%, p < 0.05 for right and 11% for left extremities) and extensors (14% for right and 18%, p < 0.05 for left extremities) and shoulder flexors (10% for right and 12%, p < 0.05 for left extremities) and extensors (11% for right and 1% for left extremities). Taekwondo WTF and taekwondo ITF athletes obtained significantly different relative values of muscle torque of the hip flexors (16%, p < 0.05) and extensors (11%, p < 0.05) of the right extremities.

Motor strategy patterns study of diabetic neuropathic individuals while walking. A wavelet approach.

PubMed

Sacco, I C N; Hamamoto, A N; Onodera, A N; Gomes, A A; Weiderpass, H A; Pachi, C G F; Yamamoto, J F; von Tscharner, V

2014-07-18

The aim of this study was to investigate muscle׳s energy patterns and spectral properties of diabetic neuropathic individuals during gait cycle using wavelet approach. Twenty-one diabetic patients diagnosed with peripheral neuropathy, and 21 non-diabetic individuals were assessed during the whole gait cycle. Activation patterns of vastus lateralis, medial gastrocnemius and tibialis anterior were studied by means of bipolar surface EMG. The signal׳s energy and frequency were compared between groups using t-test. The energy was compared in each frequency band (7-542 Hz) using ANOVAs for repeated measures for each group and each muscle. The diabetic individuals displayed lower energies in lower frequency bands for all muscles and higher energies in higher frequency bands for the extensors׳ muscles. They also showed lower total energy of gastrocnemius and a higher total energy of vastus, considering the whole gait cycle. The overall results suggest a change in the neuromuscular strategy of the main extensor muscles of the lower limb of diabetic patients to compensate the ankle extensor deficit to propel the body forward and accomplish the walking task. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

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.

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.

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.

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.

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.

Muscle Strength Imbalance in the Hip Joint Caused by Fast Movements

NASA Astrophysics Data System (ADS)

Pontaga, I.

2003-07-01

Eleven male sportsmen at the age of 24.3 ± 4.5 were examined. Their hip joint flexors and extensors were tested by an "REV-9000" Technogym dynamometer system during isokinetic movements at angular velocities of 100 (low) and 200 (high) °/s. The range of hip joint movements was from 30 (in flexion) to 130° (in extension). Torque values and their ratios for hip flexors and extensors at different angular positions were obtained and compared. It is shown that, at high speeds, the flexion movement significantly raises ( p < 0.001) the torque ratios of flexors and extensors in flexion positions of the hip (50 and 60°). These ratios approximately twofold exceed their values at moderate velocities. The weakness of hip joint extensors in extreme flexion positions of the hip may cause injury of this group of muscles at fast movements.

Acute Effects of Different Agonist and Antagonist Stretching Arrangements on Static and Dynamic Range of Motion

PubMed Central

Amiri-Khorasani, Mohammadtaghi; Kellis, Eleftherios

2015-01-01

Background: Traditionally, stretching exercises are considered as basic components of warm up aiming to prepare the musculoskeletal system for performance and to prevent injuries. Objectives: The purpose of this study was to examine the effects of different agonist and antagonist stretching arrangements within a pre-exercise warm-up on hip static (SROM) and dynamic range of motion (DROM). Materials and Methods: Sixty trained male subjects (Mean ± SD: height, 177.38 ± 6.92 cm; body mass, 68.4 ± 10.22 kg; age, 21.52 ± 1.17 years) volunteered to participate in this study. SROM was measured by V-sit test and DROM captured by a motion analysis system before and after (i) static stretching for both hip flexor and extensor muscles (SFSE), (ii) dynamic stretching for both hip flexor and extensor muscles (DFDE), (iii) static stretching for the hip flexors and dynamic stretching for hip extensors (SFDE), and (iv) dynamic stretching for the hip flexors and static stretching for hip extensors (DFSE). Results: DFSE showed a significantly higher increase in DROM and SROM than the remainder of the stretching protocols (P < 0.05). There were significant differences between DFDE with SFSE and SFDE (P < 0.05) and SFSE showed significant increase as compared to SFDE (P < 0.05). Conclusions: In conclusion, DFSE is probably the best stretching arrangement due to producing more post activation potentiation on agonist muscles and less muscle stiffness in antagonist muscles. PMID:26715975

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

Morphological and biochemical changes in soleus and extensor digitorum longus muscles of rats orbited in Spacelab 3

NASA Technical Reports Server (NTRS)

Riley, D. A.; Slocum, T.; Bain, J. L. W.; Sedlak, F. R.; Elis, S.; Satyanarayana, T.

1985-01-01

Muscle atrophy in rats exposed to hypogravity for seven days aboard Spacelab 3 is examined. Hindlimb muscles were harvested 12-16 days postflight, and prepared for enzyme studies and electron microscopy. Simple cell shrinkage was found, with a mean fiber area decrease of 35.8 percent for soleus and 24.9 percent for extensor digitorum longus (EDL) flight muscle fibers, as compared with control muscle fibers. EDL and soleus muscles showed increases in alkaline myofibrillar ATPase, alpha glycerophosphate dehydrogenase, and glycogen, and a decrease in NADH dehydrogenase staining. The 26 percent increase in calcium activated protease suggests that the focal degradation of myofibrils is the key process of myofibril breakdown. The presence in the flight soleus muscles of one percent necrotic fibers is unexplained. The observed shift towards histochemical fast-muscle type properties is consistent with previous findings.

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.

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.

Changes in the activity of trunk and hip extensor muscles during bridge exercises with variations in unilateral knee joint angle.

PubMed

Kim, Juseung; Park, Minchul

2016-09-01

[Purpose] This study compared abdominal and hip extensor muscle activity during a bridge exercise with various knee joint angles. [Subjects and Methods] Twenty-two healthy male subjects performed a bridge exercise in which the knee joint angle was altered. While subjects performed the bridge exercise, external oblique, internal oblique, gluteus maximus, and semitendinosus muscle activity was measured using electromyography. [Results] The bilateral external and internal oblique muscle activity was significantly higher at 0° knee flexion compared to 120°, 90°, and 60°. The bilateral gluteus maximus muscle activity was significantly different at 0° of knee flexion compared to 120°, 90°, and 60°. The ipsilateral semitendinosus muscle activity was significantly increased at 90° and 60° of knee flexion compared to 120°, and significantly decreased at 0° knee flexion compared with 120°, 90°, and 60°. The contralateral semitendinosus muscle activity was significantly higher at 60° of knee flexion than at 120°, and significantly higher at 0° of knee flexion than at 120°, 90°, and 60°. [Conclusion] Bridge exercises performed with knee flexion less than 90° may be used to train the ipsilateral semitendinosus. Furthermore, bridge exercise performed with one leg may be used to train abdominal and hip extensor muscles.

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.

Comparing two methods to record maximal voluntary contractions and different electrode positions in recordings of forearm extensor muscle activity: Refining risk assessments for work-related wrist disorders.

PubMed

Dahlqvist, Camilla; Nordander, Catarina; Granqvist, Lothy; Forsman, Mikael; Hansson, Gert-Åke

2018-01-01

Wrist disorders are common in force demanding industrial repetitive work. Visual assessment of force demands have a low reliability, instead surface electromyography (EMG) may be used as part of a risk assessment for work-related wrist disorders. For normalization of EMG recordings, a power grip (hand grip) is often used as maximal voluntary contraction (MVC) of the forearm extensor muscles. However, the test-retest reproducibility is poor and EMG amplitudes exceeding 100% have occasionally been recorded during work. An alternative MVC is resisted wrist extension, which may be more reliable. To compare hand grip and resisted wrist extension MVCs, in terms of amplitude and reproducibility, and to examine the effect of electrode positioning. Twelve subjects participated. EMG from right forearm extensors, from four electrode pairs, was recorded during MVCs, on three separate occasions. The group mean EMG amplitudes for resisted wrist extension were 1.2-1.7 times greater than those for hand grip. Resisted wrist extension showed better reproducibility than hand grip. The results indicate that the use of resisted wrist extension is a more accurate measurement of maximal effort of wrist extensor contractions than using hand grip and should increase the precision in EMG recordings from forearm extensor muscles, which in turn will increase the quality of risk assessments that are based on these.

The intra- and inter-rater reliability of five clinical muscle performance tests in patients with and without neck pain

PubMed Central

2013-01-01

Background This study investigates the reliability of muscle performance tests using cost- and time-effective methods similar to those used in clinical practice. When conducting reliability studies, great effort goes into standardising test procedures to facilitate a stable outcome. Therefore, several test trials are often performed. However, when muscle performance tests are applied in the clinical setting, clinicians often only conduct a muscle performance test once as repeated testing may produce fatigue and pain, thus variation in test results. We aimed to investigate whether cervical muscle performance tests, which have shown promising psychometric properties, would remain reliable when examined under conditions similar to those of daily clinical practice. Methods The intra-rater (between-day) and inter-rater (within-day) reliability was assessed for five cervical muscle performance tests in patients with (n = 33) and without neck pain (n = 30). The five tests were joint position error, the cranio-cervical flexion test, the neck flexor muscle endurance test performed in supine and in a 45°-upright position and a new neck extensor test. Results Intra-rater reliability ranged from moderate to almost perfect agreement for joint position error (ICC ≥ 0.48-0.82), the cranio-cervical flexion test (ICC ≥ 0.69), the neck flexor muscle endurance test performed in supine (ICC ≥ 0.68) and in a 45°-upright position (ICC ≥ 0.41) with the exception of a new test (neck extensor test), which ranged from slight to moderate agreement (ICC = 0.14-0.41). Likewise, inter-rater reliability ranged from moderate to almost perfect agreement for joint position error (ICC ≥ 0.51-0.75), the cranio-cervical flexion test (ICC ≥ 0.85), the neck flexor muscle endurance test performed in supine (ICC ≥ 0.70) and in a 45°-upright position (ICC ≥ 0.56). However, only slight to fair agreement was found for the neck extensor test (ICC = 0.19-0.25). Conclusions Intra- and inter-rater reliability ranged from moderate to almost perfect agreement with the exception of a new test (neck extensor test), which ranged from slight to moderate agreement. The significant variability observed suggests that tests like the neck extensor test and the neck flexor muscle endurance test performed in a 45°-upright position are too unstable to be used when evaluating neck muscle performance. PMID:24299621

Role of glucocorticoids in increased muscle glutamine production in starvation

NASA Technical Reports Server (NTRS)

Tischler, Marc E.; Henriksen, Erik J.; Cook, Paul H.

1988-01-01

The role of glucocorticoids in the synthesis of muscle glutamine during starvation was investigated in adrenalectomized fasted rats injected with cortisol (1 mg/100 g body weight). It was found that administration of cortisol in vivo increased (compared to nontreated starved adrenalectomized controls) the glutamine/glutamate ratio and the activity of glutamine synthetase in the diaphragm and the extensor digitorum muscles, and that these effects were abolished by prior treatment with actinomycin D or proflavine. The results obtained in in vitro experiments, using fresh-frozen soleus, extensor digitorum longus, and diaphragm muscle preparations, supported the in vivo indications of the cortisol-enhanced glutamine synthesis and protein turnover in starved adrenalectomized animals.

The relationship between EMG activity and extensor moment generation in the erector spinae muscles during bending and lifting activities.

PubMed

Dolan, P; Adams, M A

1993-01-01

The relationship between EMG activity and extensor moment generation in the erector spinae muscles was investigated under isometric and concentric conditions. The full-wave rectified and averaged EMG signal was recorded from skin-surface electrodes located over the belly of the erector spinae at the levels of T10 and L3, and compared with measurements of extensor moment. The effects of muscle length and contraction velocity were studied by measuring the overall curvature (theta) and rate of change of curvature (d theta/dt) of the lumbar spine in the sagittal plane, using the '3-Space Isotrak' system. Isometric contractions were investigated with the subjects pulling up on a load cell attached to the floor. Hand height was varied to produce different amounts of lumbar flexion, as indicated by changes in lumbar curvature. The extensor moment was found to be linearly related to EMG activity, and the 'gradient' and 'intercept' of the relationship were themselves dependent upon the lumbar curvature at the time of testing. Concentric contractions were investigated with the subjects extending from a seated toe-touching position, at various speeds, while the torque exerted on the arm of a Cybex dynamometer was continuously measured. Under these conditions the EMG signal (E) was higher than the isometric signal (E0) associated with the same torque. E and E0 were related as follows: E0 = E/(1 + A d theta/dt), where A = 0.0014 exp (0.045P) and P = percentage lumbar flexion. This equation was used to correct the EMG data for the effect of contraction velocity. The corrected data were then used, in conjunction with the results of the isometric calibrations, to calculate the extensor moment generated by the erector spinae muscles during bending and lifting activities. The extensor moment can itself be used to calculate the compressive force acting on the lumbar spine.

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

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.

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.

Hypogravity-induced atrophy of rat soleus and extensor digitorum longus muscles

NASA Technical Reports Server (NTRS)

Riley, D. A.; Ellis, S.; Slocum, G. R.; Satyanarayana, T.; Bain, J. L.; Sedlak, F. R.

1987-01-01

Prolonged exposure of humans to hypogravity causes weakening of their skeletal muscles. This problem was studied in rats exposed to hypogravity for 7 days aboard Spacelab 3. Hindlimb muscles were harvested 12-16 hours postflight for histochemical, biochemical, and ultrastructural analyses. The majority of the soleus and extensor digitorum longus fibers exhibited simple cell shrinkage. However, approximately 1% of the fibers in flight soleus muscles appeared necrotic. Flight muscle fibers showed increased glycogen, lower subsarcolemmal staining for mitochondrial enzymes, and fewer subsarcolemmal mitochondria. During atrophy, myofibrils were eroded by multiple focal losses of myofilaments; lysosomal autophagy was not evident. Tripeptidylaminopeptidase and calcium-activated protease activities of flight soleus fibers were significantly increased, implying a role in myofibril breakdown. Simple fiber atrophy appears to account for muscle weakening during spaceflight, but fiber necrosis is also a contributing factor.

Effect of hindlimb suspension and clenbuterol treatment on polyamine levels in skeletal muscle

NASA Technical Reports Server (NTRS)

Abukhalaf, Imad K.; von Deutsch, Daniel A.; Wineski, Lawrence E.; Silvestrov, Natalia A.; Abera, Saare A.; Sahlu, Sinafikish W.; Potter, David E.; Thierry-Palmer, M. (Principal Investigator)

2002-01-01

Polyamines are unbiquitous, naturally occurring small aliphatic, polycationic, endogenous compounds. They are involved in many cellular processes and may serve as secondary or tertiary messengers to hormonal regulation. The relationship of polyamines and skeletal muscle mass of adductor longus, extensor digitorum longus, and gastrocnemius under unloading (hindlimb suspension) conditions was investigated. Unloading significantly affected skeletal muscle polyamine levels in a fiber-type-specific fashion. Under loading conditions, clenbuterol treatment increased all polyamine levels, whereas under unloading conditions, only the spermidine levels were consistently increased. Unloading attenuated the anabolic effects of clenbuterol in predominately slow-twitch muscles (adductor longus), but had little impact on clenbuterol's action as a countermeasure in fast- twitch muscles such as the extensor digitorum longus. Spermidine appeared to be the primary polyamine involved in skeletal muscle atrophy/hypertrophy. Copyright 2002 S. Karger AG, Basel.

Estimation method of finger tapping dynamics using simple magnetic detection system

NASA Astrophysics Data System (ADS)

Kandori, Akihiko; Sano, Yuko; Miyashita, Tsuyoshi; Okada, Yoshihisa; Irokawa, Masataka; Shima, Keisuke; Tsuji, Toshio; Yokoe, Masaru; Sakoda, Saburo

2010-05-01

We have developed the simple estimation method of a finger tapping dynamics model for investigating muscle resistance and stiffness during tapping movement in normal subjects. We measured finger tapping movements of 207 normal subjects using a magnetic finger tapping detection system. Each subject tapped two fingers in time with a metronome at 1, 2, 3, 4, and 5 Hz. The velocity and acceleration values for both the closing and opening tapping data were used to estimate a finger tapping dynamics model. Using the frequency response of the ratio of acceleration to velocity of the mechanical impedance parameters, we estimated the resistance (friction coefficient) and compliance (stiffness). We found two dynamics models for the maximum open position and tap position. In the maximum open position, the extensor muscle resistance was twice as high as the flexor muscle resistance and males had a higher spring constant. In the tap position, the flexor muscle resistance was much higher than the extensor muscle resistance. This indicates that the tapping dynamics in the maximum open position are controlled by the balance of extensor and flexor muscle friction resistances and the flexor stiffness, and the flexor friction resistance is the main component in the tap position. It can be concluded that our estimation method makes it possible to understand the tapping dynamics.

Estimation method of finger tapping dynamics using simple magnetic detection system.

PubMed

Kandori, Akihiko; Sano, Yuko; Miyashita, Tsuyoshi; Okada, Yoshihisa; Irokawa, Masataka; Shima, Keisuke; Tsuji, Toshio; Yokoe, Masaru; Sakoda, Saburo

2010-05-01

We have developed the simple estimation method of a finger tapping dynamics model for investigating muscle resistance and stiffness during tapping movement in normal subjects. We measured finger tapping movements of 207 normal subjects using a magnetic finger tapping detection system. Each subject tapped two fingers in time with a metronome at 1, 2, 3, 4, and 5 Hz. The velocity and acceleration values for both the closing and opening tapping data were used to estimate a finger tapping dynamics model. Using the frequency response of the ratio of acceleration to velocity of the mechanical impedance parameters, we estimated the resistance (friction coefficient) and compliance (stiffness). We found two dynamics models for the maximum open position and tap position. In the maximum open position, the extensor muscle resistance was twice as high as the flexor muscle resistance and males had a higher spring constant. In the tap position, the flexor muscle resistance was much higher than the extensor muscle resistance. This indicates that the tapping dynamics in the maximum open position are controlled by the balance of extensor and flexor muscle friction resistances and the flexor stiffness, and the flexor friction resistance is the main component in the tap position. It can be concluded that our estimation method makes it possible to understand the tapping dynamics.

Vibration-induced muscle injury. An experimental model and preliminary findings.

PubMed

Necking, L E; Dahlin, L B; Fridén, J; Lundborg, G; Lundström, R; Thornell, L E

1992-06-01

The hind paws of rats were subjected to vibration at a frequency of 80 Hz., an acceleration of 32 m./s.2 rms (i.e. ah.w approximately 6.3 m./s.2 rms) for five hours daily during five consecutive days. Morphological, histochemical and immunohistochemical analyses of the soleus, extensor digitorum longus and the plantar muscles in the vibrated limb and the contralateral control limb were performed. No changes were seen in the soleus or extensor digitorum longus muscles but different degrees of degeneration of the muscle fibres were seen in the plantar muscle sections as well as signs of regeneration. No changes were observed in the contralateral unexposed limb. It is concluded that it is not only nervous tissue but also muscle tissue that can be affected by vibration. The changes seem to be confined to muscles close to the vibration exciter.

Prevalence of and referred pain from myofascial trigger points in the forearm muscles in patients with lateral epicondylalgia.

PubMed

Fernández-Carnero, Josué; Fernández-de-Las-Peñas, César; de la Llave-Rincón, Ana Isabel; Ge, Hong-You; Arendt-Nielsen, Lars

2007-05-01

Referred pain and pain characteristics evoked from the extensor carpi radialis brevis, extensor carpi radialis longus, extensor digitorum communis, and brachioradialis muscles was investigated in 20 patients with lateral epicondylalgia (LE) and 20-matched controls. Both groups were examined for the presence of myofascial trigger points (TrPs) in a blinded fashion. The quality and location of the evoked referred pain, and the pressure pain threshold (PPT) at the lateral epicondyle on the right upper extremity (symptomatic side in patients, and dominant-side on controls) were recorded. Several lateral elbow pain parameters were also evaluated. Within the patient group, the elicited referred pain by manual exploration of 13 out of 20 (65%) extensor carpi radialis brevis muscles, 12/20 (70%) extensor carpi radialis longus muscles, 10/20 (50%) brachioradialis muscles, and 5/20 (25%) extensor digitorum communis muscles, shares similar pain patterns as their habitual lateral elbow and forearm pain. The mean number of muscles with TrPs for each patient was 2.9 [95% confidence interval (CI) 1,4] of which 2 (95% CI 1,3) were active, and 0.9 (95% CI 0,2) were latent TrPs. Control participants only had latent TrPs (mean: 0.4; 95% CI 0,2). TrP occurrence between the 2 groups was significantly different for active TrPs (P<0.001), but not for latent TrPs (P>0.05). The referred pain pattern was larger in patients than in controls, with pain referral to the lateral epicondyle (proximally) and to the dorso-lateral aspect of the forearm in the patients, and confined to the dorso-lateral aspect of the forearm in the controls. Patients with LE showed a significant (P<0.001) lower PPT (mean: 2.1 kg/cm; 95% CI 0.8, 4 kg/cm) as compared with controls (mean: 4.5 kg/cm; 95% CI 3, 7 kg/cm). Within the patient group, PPT at the lateral epicondyle was negatively correlated with both the total number of TrPs (rs=-0.63; P=0.003) and the number of active TrPs (rs=-0.5; P=0.02): the greater the number of active TrPs, the lower the PPT at the lateral epicondyle. Our results suggest that in patients with LE, the evoked referred pain and its sensory characteristics shared similar patterns as their habitual elbow and forearm pain, consistent with active TrPs. Lower PPT and larger referred pain patterns suggest that peripheral and central sensitization exists in LE.

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

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.

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

Monosynaptic Ia projections from intrinsic hand muscles to forearm motoneurones in humans.

PubMed

Marchand-Pauvert, V; Nicolas, G; Pierrot-Deseilligny, E

2000-05-15

Heteronymous Ia excitatory projections from intrinsic hand muscles to human forearm motoneurones (MNs) were investigated. Changes in firing probability of single motor units (MUs) in the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), extensor carpi radialis (ECR), extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC) were studied after electrical stimuli were applied to the median and ulnar nerve at wrist level and to the corresponding homonymous nerve at elbow level. Homonymous facilitation, occurring at the same latency as the H reflex, and therefore attributed to monosynaptic Ia EPSPs, was found in all the sampled units. In many MUs an early facilitation was also evoked by heteronymous low-threshold afferents from intrinsic hand muscles. The low threshold (between 0.5 and 0.6 times motor threshold (MT)) and the inability of a pure cutaneous stimulation to reproduce this effect indicate that it is due to stimulation of group I muscle afferents. Evidence for a similar central delay (monosynaptic) in heteronymous as in homonymous pathways was accepted when the difference in latencies of the homonymous and heteronymous peaks did not differ from the estimated supplementary afferent conduction time from wrist to elbow level by more than 0.5 ms (conduction velocity in the fastest Ia afferents between wrist and elbow levels being equal to 69 m s-1). A statistically significant heteronymous monosynaptic Ia excitation from intrinsic hand muscles supplied by both median and ulnar nerves was found in MUs belonging to all forearm motor nuclei tested (although not in ECU MUs after ulnar stimulation). It was, however, more often found in flexors than in extensors, in wrist than in finger muscles and in muscles operating in the radial than in the ulnar side. It is argued that the connections of Ia afferents from intrinsic hand muscles to forearm MNs, which are stronger and more widely distributed than in the cat, might be used to provide a support to the hand during manipulatory movements.

The role of muscle strengthening in exercise therapy for knee osteoarthritis: A systematic review and meta-regression analysis of randomized trials.

PubMed

Bartholdy, Cecilie; Juhl, Carsten; Christensen, Robin; Lund, Hans; Zhang, Weiya; Henriksen, Marius

2017-08-01

To analyze if exercise interventions for patients with knee osteoarthritis (OA) following the American College of Sports Medicine (ACSM) definition of muscle strength training differs from other types of exercise, and to analyze associations between changes in muscle strength, pain, and disability. A systematic search in 5 electronic databases was performed to identify randomized controlled trials comparing exercise interventions with no intervention in knee OA, and reporting changes in muscle strength and in pain or disability assessed as standardized mean differences (SMD) with 95% confidence intervals (95% CI). Interventions were categorized as ACSM interventions or not-ACSM interventions and compared using stratified random effects meta-analysis models. Associations between knee extensor strength gain and changes in pain/disability were assessed using meta-regression analyses. The 45 eligible trials with 4699 participants and 56 comparisons (22 ACSM interventions) were included in this analysis. A statistically significant difference favoring the ACSM interventions with respect to knee extensor strength was found [SMD difference: 0.448 (95% CI: 0.091-0.805)]. No differences were observed regarding effects on pain and disability. The meta-regressions indicated that increases in knee extensor strength of 30-40% would be necessary for a likely concomitant beneficial effect on pain and disability, respectively. Exercise interventions following the ACSM criteria for strength training provide superior outcomes in knee extensor strength but not in pain or disability. An increase of less than 30% in knee extensor strength is not likely to be clinically beneficial in terms of changes in pain and disability (PROSPERO: CRD42014015344). Copyright © 2017 Elsevier Inc. All rights reserved.

Long-term wheel running compromises diaphragm function but improves cardiac and plantarflexor function in the mdx mouse

PubMed Central

Acosta, Pedro; Sleeper, Meg M.; Barton, Elisabeth R.; Sweeney, H. Lee

2013-01-01

Dystrophin-deficient muscles suffer from free radical injury, mitochondrial dysfunction, apoptosis, and inflammation, among other pathologies that contribute to muscle fiber injury and loss, leading to wheelchair confinement and death in the patient. For some time, it has been appreciated that endurance training has the potential to counter many of these contributing factors. Correspondingly, numerous investigations have shown improvements in limb muscle function following endurance training in mdx mice. However, the effect of long-term volitional wheel running on diaphragm and cardiac function is largely unknown. Our purpose was to determine the extent to which long-term endurance exercise affected dystrophic limb, diaphragm, and cardiac function. Diaphragm specific tension was reduced by 60% (P < 0.05) in mice that performed 1 yr of volitional wheel running compared with sedentary mdx mice. Dorsiflexor mass (extensor digitorum longus and tibialis anterior) and function (extensor digitorum longus) were not altered by endurance training. In mice that performed 1 yr of volitional wheel running, plantarflexor mass (soleus and gastrocnemius) was increased and soleus tetanic force was increased 36%, while specific tension was similar in wheel-running and sedentary groups. Cardiac mass was increased 15%, left ventricle chamber size was increased 20% (diastole) and 18% (systole), and stroke volume was increased twofold in wheel-running compared with sedentary mdx mice. These data suggest that the dystrophic heart may undergo positive exercise-induced remodeling and that limb muscle function is largely unaffected. Most importantly, however, as the diaphragm most closely recapitulates the human disease, these data raise the possibility of exercise-mediated injury in dystrophic skeletal muscle. PMID:23823150

Knee Extensor Rate of Torque Development Before and After Arthroscopic Partial Meniscectomy, With Analysis of Neuromuscular Mechanisms.

PubMed

Cobian, Daniel G; Koch, Cameron M; Amendola, Annunziato; Williams, Glenn N

2017-12-01

Study Design Descriptive, prospective single-cohort longitudinal study. Background Though rapid torque development is essential in activities of daily living and sports, it hasn't been specifically tested by most physical therapists or incorporated into rehabilitation programs until late in the treatment process. Little evidence is available on quadriceps torque development capacity before and after arthroscopic knee surgery. Objectives To study knee extensor rate of torque development, contributing mechanisms, and associations with strength and patient-reported outcomes before and during the first 6 weeks after arthroscopic partial meniscectomy. Methods Twenty subjects (mean ± SD age, 42.3 ± 13.7 years; body mass index, 26.6 ± 3.1 kg/m 2 ) were tested before surgery, and at 2 and 5 weeks after surgery. Quadriceps muscle volume, strength, activation, rate of torque development, and patient-reported outcomes were evaluated across the study period. Results Significant side-to-side differences in quadriceps strength and voluntary rate of torque development were observed at each time point (P<.05). Changes in muscle activity were associated with changes in rapid torque development capacity. Side-to-side rate of torque development deficits after surgery were associated with lower patient-reported outcomes scores. Conclusion Diminished rapid torque development capacity is common in arthroscopic meniscal debridement patients. This reduced capacity is associated with an inability to quickly recruit and drive the quadriceps muscles (neural mechanisms) and not muscle atrophy or other peripheral factors tested. Patient-reported outcomes are associated with quadriceps rate of torque development, but not strength or muscle size. Rapid torque development warrants greater attention in rehabilitation. J Orthop Sports Phys Ther 2017;47(12):945-956. Epub 9 Oct 2017. doi:10.2519/jospt.2017.7310.

Validity of trunk extensor and flexor torque measurements using isokinetic dynamometry.

PubMed

Guilhem, Gaël; Giroux, Caroline; Couturier, Antoine; Maffiuletti, Nicola A

2014-12-01

This study aimed to evaluate the validity and test-retest reliability of trunk muscle strength testing performed with a latest-generation isokinetic dynamometer. Eccentric, isometric, and concentric peak torque of the trunk flexor and extensor muscles was measured in 15 healthy subjects. Muscle cross sectional area (CSA) and surface electromyographic (EMG) activity were respectively correlated to peak torque and submaximal isometric torque for erector spinae and rectus abdominis muscles. Reliability of peak torque measurements was determined during test and retest sessions. Significant correlations were consistently observed between muscle CSA and peak torque for all contraction types (r=0.74-0.85; P<0.001) and between EMG activity and submaximal isometric torque (r ⩾ 0.99; P<0.05), for both extensor and flexor muscles. Intraclass correlation coefficients were comprised between 0.87 and 0.95, and standard errors of measurement were lower than 9% for all contraction modes. The mean difference in peak torque between test and retest ranged from -3.7% to 3.7% with no significant mean directional bias. Overall, our findings establish the validity of torque measurements using the tested trunk module. Also considering the excellent test-retest reliability of peak torque measurements, we conclude that this latest-generation isokinetic dynamometer could be used with confidence to evaluate trunk muscle function for clinical or athletic purposes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Soreness-related changes in three-dimensional running biomechanics following eccentric knee extensor exercise.

PubMed

Paquette, Max R; Peel, Shelby A; Schilling, Brian K; Melcher, Dan A; Bloomer, Richard J

2017-06-01

Runners often experience delayed onset muscle soreness (DOMS), especially of the knee extensors, following prolonged running. Sagittal knee joint biomechanics are altered in the presence of knee extensor DOMS but it is unclear how muscle soreness affects lower limb biomechanics in other planes of motion. The purpose of this study was to assess the effects of knee extensor DOMS on three-dimensional (3D) lower limb biomechanics during running. Thirty-three healthy men (25.8 ± 6.8 years; 84.1 ± 9.2 kg; 1.77 ± 0.07 m) completed an isolated eccentric knee extensor damaging protocol to elicit DOMS. Biomechanics of over-ground running at a set speed of 3.35 m s -1 ±5% were measured before eccentric exercise (baseline) and, 24 h and 48 h following exercise in the presence of knee extensor DOMS. Knee flexion ROM was reduced at 48 h (P = 0.01; d = 0.26), and peak knee extensor moment was reduced at 24 h (P = 0.001; d = 0.49) and 48 h (P < 0.001; d = 0.68) compared to baseline. Frontal and transverse plane biomechanics were unaffected by the presence of DOMS (P > 0.05). Peak positive ankle and knee joint powers and, peak negative knee joint power were all reduced from baseline to 24 h and 48 h (P < 0.05). These findings suggest that knee extensor DOMS greatly influences sagittal knee joint angular kinetics and, reduces sagittal power production at the ankle joint. However, knee extensor DOMS does not affect frontal and transverse plane lower limb joint biomechanics during running.

Muscle function in elite master weightlifters.

PubMed

Pearson, Stephen J; Young, Archie; Macaluso, Andrea; Devito, Giuseppe; Nimmo, Myra A; Cobbold, Matthew; Harridge, Stephen D R

2002-07-01

To determine whether explosive power and isometric strength of the lower-limb muscles in elite master Olympic weightlifters declines at a similar rate to nontrained healthy controls with increasing age. 54 elite level masters weightlifters (aged 40-87), who were competitors at the World Masters Weightlifting Championships (1999), were compared with a similar number of aged-matched, healthy untrained individuals. Isometric knee extensor strength and lower-limb explosive power were tested. Extent of antagonist co-contraction during isometric knee extension was determined by EMG and power loading characteristics by using a variable inertial system. Muscle volume was estimated using anthropometry. On average, the weightlifters were able to generate 32% more peak power (P < 0.05) in the lower limbs and 32% more isometric knee extensor force (P < 0.05) than the control subjects. No significant differences in lower-leg volume were observed between the two groups. Peak power declined at a similar rate with increasing age in the weightlifters and controls (1.2 and 1.3% of a 45-yr-old's value per year), as did strength, but at a lower rate (0.6 and 0.5% per year). The inertial load at which the weightlifters achieved their maximal peak power output was greater (P < 0.05) than the controls. The torque generated at this optimal inertia was also greater in the weightlifters (P < 0.05), whereas the time taken for the weightlifters to reach their maximal peak power was on average 13% shorter (P < 0.05). No differences in antagonist co-contraction during isometric knee extension were observed between the two groups. Muscle power and isometric strength decline at a similar rate with increasing age in elite master weightlifters and healthy controls. In spite of inertial load optimization, muscle power declined in both groups at approximately twice the rate of isometric strength. Although similar rates of decline were observed, the absolute differences between the weightlifters and controls were such that an 85-yr-old weightlifter was as powerful as a 65-yr-old control subject. This would therefore represent an apparent age advantage of approximately 20 yr for the weightlifters.

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.

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.

Cross-spectral analysis of physiological tremor and muscle activity. I. Theory and application to unsynchronized electromyogram.

PubMed

Timmer, J; Lauk, M; Pfleger, W; Deuschl, G

1998-05-01

We investigate the relationship between the extensor electromyogram (EMG) and tremor times series in physiological hand tremor by cross-spectral analysis. Special attention is directed to the phase spectrum and the effects of observational noise. We calculate the theoretical phase spectrum for a second-order linear stochastic process and compare the results to measured tremor data recorded from subjects who did not show a synchronized EMG activity in the corresponding extensor muscle. The results show that physiological tremor is well described by the proposed model and that the measured EMG represents a Newtonian force by which the muscle acts on the hand.

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.

Satellite cell depletion prevents fiber hypertrophy in skeletal muscle.

PubMed

Egner, Ingrid M; Bruusgaard, Jo C; Gundersen, Kristian

2016-08-15

The largest mammalian cells are the muscle fibers, and they have multiple nuclei to support their large cytoplasmic volumes. During hypertrophic growth, new myonuclei are recruited from satellite stem cells into the fiber syncytia, but it was recently suggested that such recruitment is not obligatory: overload hypertrophy after synergist ablation of the plantaris muscle appeared normal in transgenic mice in which most of the satellite cells were abolished. When we essentially repeated these experiments analyzing the muscles by immunohistochemistry and in vivo and ex vivo imaging, we found that overload hypertrophy was prevented in the satellite cell-deficient mice, in both the plantaris and the extensor digitorum longus muscles. We attribute the previous findings to a reliance on muscle mass as a proxy for fiber hypertrophy, and to the inclusion of a significant number of regenerating fibers in the analysis. We discuss that there is currently no model in which functional, sustainable hypertrophy has been unequivocally demonstrated in the absence of satellite cells; an exception is re-growth, which can occur using previously recruited myonuclei without addition of new myonuclei. © 2016. Published by The Company of Biologists Ltd.

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.

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.

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.

Muscle strength and fatigue in newly diagnosed patients with myasthenia gravis.

PubMed

Vinge, Lotte; Andersen, Henning

2016-10-01

Dynamometry is increasingly used as an objective measurement of muscle strength in neurological diseases. No study has applied dynamometry in untreated newly diagnosed patients with myasthenia gravis (MG). Isometric muscle strength at the shoulder, knee, and ankle was determined in 21 MG patients before and after initial anti-myasthenic treatment. Isometric strength was compared with MG evaluation scales. Muscle strength was reduced for knee extensors and shoulder abductors but normal for ankle extensors. Isometric muscle strength did not correlate significantly with manual muscle testing (MG Composite). Dynamometry revealed improved muscle strength of up to 50% (median 17%; range -1.8-49.8) despite no change in the MG Composite score. Dynamometry appears to be a more sensitive method of identifying changes in limb strength than MG evaluation scales. This supports the use of dynamometry in MG patients, especially for evaluation of the effect of anti-myasthenic treatment. Muscle Nerve 54: 709-714, 2016. © 2016 Wiley Periodicals, Inc.

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.

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

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)

Ipsilateral hip abductor weakness after inversion ankle sprain.

PubMed

Friel, Karen; McLean, Nancy; Myers, Christine; Caceres, Maria

2006-01-01

Hip stability and strength are important for proper gait mechanics and foot position during heel strike. To determine the relationships between hip muscle strength and chronic ankle sprains and hip muscle strength and ankle range of motion. Ex post facto design with the uninvolved limb serving as the control. Laboratory. A total of 23 subjects with unilateral chronic ankle sprain were recruited. Subjects had at least 2 ipsilateral ankle sprains and were bearing full weight, with the most recent injury occurring at least 3 months earlier. They were not undergoing formal or informal rehabilitation at the time of the study. We obtained goniometric measurements for all planes of motion at the ankle. Handheld dynamometry was used to assess the strength of the hip abductor and hip extensor muscles in both limbs. Hip abductor muscle strength and plantar flexion were significantly less on the involved side than the uninvolved side (P < .001 in each case). Strength of the involved hip abductor and hip extensor muscles was significantly correlated (r = 0.539, P < .01). No significant difference was noted in hip extensor muscle strength between sides (P = .19). Our subjects with unilateral chronic ankle sprains had weaker hip abduction strength and less plantar-flexion range of motion on the involved sides. Clinicians should consider exercises to increase hip abduction strength when developing rehabilitation programs for patients with ankle sprains.

Hypodynamic and hypokinetic condition of skeletal muscles

NASA Technical Reports Server (NTRS)

Katinas, G. S.; Oganov, V. S.; Potapov, A. N.

1980-01-01

Data are presented in regard to the effect of unilateral brachial amputation on the physiological characteristics of two functionally different muscles, the brachial muscle (flexor of the brachium) and the medial head of the brachial triceps muscle (extensor of the brachium), which in rats represents a separate muscle. Hypokinesia and hypodynamia were studied.

Isometric elbow extensors strength in supine- and prone-lying positions.

PubMed

Abdelzaher, Ibrahim E; Ababneh, Anas F; Alzyoud, Jehad M

2013-01-01

The purpose of this study was to compare isometric strength of elbow extensors measured in supine- and prone-lying positions at elbow flexion angles of 45 and 90 degrees. Twenty-two male subjects under single-blind procedures participated in the study. Each subject participated in both supine-lying and prone-lying measuring protocols. Calibrated cable tensiometer was used to measure isometric strength of the right elbow extensors and a biofeedback electromyography was used to assure no substitution movements from shoulder girdle muscles. The mean values of isometric strength of elbow extensors measured from supine-lying position at elbow flexion angles of 45 and 90 degrees were 11.1  ±  4.2 kg and 13.1  ±  4.6 kg, while those measured from prone-lying position were 9.9  ±  3.6 kg and 12  ±  4.2 kg, respectively. There is statistical significant difference between the isometric strength of elbow extensors measured from supine-lying position at elbow flexion angles of 45 and 90 degrees compared to that measured from prone-lying position (p  <  0.05). The results suggest that in manual muscle testing starting position can affect the isometric strength of elbow extensors since supine-lying starting position is better than prone-lying starting position.

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.

Catalase-positive microperoxisomes in rat soleus and extensor digitorum longus muscle fiber types

NASA Technical Reports Server (NTRS)

Riley, Danny A.; Bain, James L. W.; Ellis, Stanley

1988-01-01

The size, distribution, and content of catalase-reactive microperoxisomes were investigated cytochemically in three types of muscle fibers from the soleus and the extensor digitorum longus (EDL) of male rats. Muscle fibers were classified on the basis of the mitochondrial content and distribution, the Z-band widths, and the size and shape of myofibrils as the slow-twitch oxidative (SO), the fast-twitch oxidative glycolytic (FOG), and the fast-twitch glycolytic (FG) fibers. It was found that both the EDL and soleus SO fibers possessed the largest microperoxisomes. A comparison of microperoxisome number per muscle fiber area or the microperoxisome area per fiber area revealed following ranking, starting from the largest number and the area-ratio values: soleus SO, EDL SO, EDL FOG, and EDL FG.

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

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

[Upright posture of man and morphologic evolution of the musculi extensores digitorum pedis with reference to evolutionary myology. III].

PubMed

Kaneff, A

1986-01-01

The following anatomical objects were studied with regard to myology during evolution: M. extensor hallucis longus (MEHL), M. extensor digitorum longus (MEDL) with M. peroneus tertius (MP III), M. peroneus brevis (MPB) with M. peroneus digiti V (MPD V), M. extensor hallucis brevis (MEHB), M. extensor digitorum brevis (MEDB), and the Retinaculum musculorum extensorum imum (RMEI). The study was carried out by the preparation of 3 different groups of material. The 1st group consists of lower extremities of humans. The number of the extremities differs for the particular objects between 151 and 358 (see page 381). The 2nd group of material consists of 122 Membra pelvina from Marsupialia, Insectivora, and Primates. Table 1 shows as well the mammalian species as the number of the studied extremities. The extremities of the 1st and 2nd group were preserved in an manner suitable for a macroscopic preparation. The 3rd group of material consists of 71 lower extremities from embryos and fetus. The lower legs and feet were stained either according to the method described by Morel and Bassal with eosin added or according to Weigert. From this material, complete series of cross sections were prepared. Table 2 shows the age of the embryos (VCL [mm]) as well as the number of the studied extremities. It is important that up to the age of 46 mm VCL the difference in the age of the embryos usually amounts from 0.5 to 1.0 mm. This small difference in the age of the embryos and fetus allows a very good follow up of the changes in construction during the organogenesis. The comparison of the 3 different groups shows the following changes for the above mentioned muscles: The M. extensor hallucis longus (MEHL) is a muscle which is not split. The same result applies for its tendon which inserts at the distal phalanx of the hallux. This primitive form of the muscle amounts actually to 51.12% in human beings. In 48.88% of the cases, additional tendons and muscles are formed by the MEHL. Most of these supplements are positioned on the medial side of the main tendon, only a few lie to the lateral side. For the supplement tendons, the medial one as well as the lateral one occasionally possess a muscle belly. The muscle of the medial tendon is split off from the proximal margin of the MEHL. The muscle of the lateral tendon is split off from the distal margin of the MEHL.(ABSTRACT TRUNCATED AT 400 WORDS)

Cold shivering activity after unilateral destruction of the vestibular apparatus

NASA Technical Reports Server (NTRS)

Kuzmina, G. I.

1980-01-01

The bioelectric activity of muscles (flexors and extensors of the forelimbs and hindlimbs) during cold shivering after unilateral destruction of the vestibular apparatus. It was found, that unilateral delabyrinthing produces bilateral facilitation of cold shivering in the flexor extremities more pronounced on the ipsilateral side. In the extensor muscles there was an absence of bioelectric activity both before and after delabyrinthing. Enhancement of cold shivering in the flexor extremities following intervention was evidently conditioned by removal of the inhibiting effect of the vestibulary apparatus on the function of special centers.

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.

Divergent skeletal muscle respiratory capacities in rats artificially selected for high and low running ability: a role for Nor1?

PubMed Central

Stephenson, Erin J.; Stepto, Nigel K.; Koch, Lauren G.; Britton, Steven L.

2012-01-01

Inactivity-related diseases are becoming a huge burden on Western society. While there is a major environmental contribution to metabolic health, the intrinsic properties that predispose or protect against particular health traits are harder to define. We used rat models of inborn high running capacity (HCR) and low running capacity (LCR) to determine inherent differences in mitochondrial volume and function, hypothesizing that HCR rats would have greater skeletal muscle respiratory capacity due to an increase in mitochondrial number. Additionally, we sought to determine if there was a link between the expression of the orphan nuclear receptor neuron-derived orphan receptor (Nor)1, a regulator of oxidative metabolism, and inherent skeletal muscle respiratory capacity. LCR rats were 28% heavier (P < 0.0001), and fasting serum insulin concentrations were 62% greater than in HCR rats (P = 0.02). In contrast, HCR rats had better glucose tolerance and reduced adiposity. In the primarily oxidative soleus muscle, maximal respiratory capacity was 21% greater in HCR rats (P = 0.001), for which the relative contribution of fat oxidation was 20% higher than in LCR rats (P = 0.02). This was associated with increased citrate synthase (CS; 33%, P = 0.009) and β-hydroxyacyl-CoA (β-HAD; 33%, P = 0.0003) activities. In the primarily glycolytic extensor digitum longus muscle, CS activity was 29% greater (P = 0.01) and β-HAD activity was 41% (P = 0.0004) greater in HCR rats compared with LCR rats. Mitochondrial DNA copy numbers were also elevated in the extensor digitum longus muscles of HCR rats (35%, P = 0.049) and in soleus muscles (44%, P = 0.16). Additionally, HCR rats had increased protein expression of individual mitochondrial respiratory complexes, CS, and uncoupling protein 3 in both muscle types (all P < 0.05). In both muscles, Nor1 protein was greater in HCR rats compared with LCR rats (P < 0.05). We propose that the differential expression of Nor1 may contribute to the differences in metabolic regulation between LCR and HCR phenotypes. PMID:22936731

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.

Skeletal muscle responses to unloading in humans

NASA Technical Reports Server (NTRS)

Dudley, G.; Tesch, P.; Hather, B.; Adams, G.; Buchanan, P.

1992-01-01

This study examined the effects of unloading on skeletal muscle structure. Method: Eight subjects walked on crutches for six weeks with a 110 cm elevated sole on the right shoe. This removed weight bearing by the left lower limb. Magnetic resonance imaging of both lower limbs and biopsies of the left m. vastus laterallis (VL) were used to study muscle structure. Results: Unloading decreased (P less than 0.05) muscle cross-sectional areas (CSA) of the knee extensors 16 percent. The knee flexors showed about 1/2 of this response (-7 percent, P less than 0.05). The three vasti muscles each showed decreases (P less than 0.05) of about 15 percent. M. rectus femoris did not change. Mean fiber CSA in VL decreased (P less than 0.05) 14 percent with type 2 and type 1 fibers showing reductions of 15 and 11 percent respectively. The ankle extensors showed a 20 percent decrease (P less than 0.05) in CSA. The reduction for the 'fast' m. gastrocnemius was 27 percent compared to the 18 percent decrease for the 'slow' soleus. Summary: The results suggest that decreases in muscle CSA are determined by the relative change in impact loading history because atrophy was (1) greater in extensor than flexor muscles, (2) at least as great in fast as compared to slow muscles or fibers, and (3) not dependent on single or multi-joint function. They also suggest that the atrophic responses to unloading reported for lower mammals are quantitatively but not qualitatively similar to those of humans.

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.

Muscle strength at the trunk*.

PubMed

Smidt, G L; Amundsen, L R; Dostal, W F

1980-01-01

The purpose of this study was to determine the strength of trunk flexors and extensors in normal male subjects during isometric, concentric, and eccentric contractions. Subjects were tested in the sidelying position to minimize the effects of gravity. The pelvis and lower extremities were measured on a custom built force table (lowa Force Table). Muscle strength was expressed as a moment of force (external force times the moment arm) in Newton-meter (Nm) units. Greater Nm were registered in the muscle-lengthened position than in the muscle-shortened position for all isometric contractions. The Nm registered for eccentric contractions always exceeded the Nm registered for concentric contractions of the same muscle group. The Nm registered during contractions of trunk extensors always exceeded the values obtained during corresponding modes of contractions (isometric, eccentric, and concentric) of trunk flexors.J Orthop Sports Phys Ther 1980;1(3):165-170.

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.

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.

Evaluation of Relationship between Trunk Muscle Endurance and Static Balance in Male Students

PubMed Central

Barati, Amirhossein; SafarCherati, Afsaneh; Aghayari, Azar; Azizi, Faeze; Abbasi, Hamed

2013-01-01

Purpose Fatigue of trunk muscle contributes to spinal instability over strenuous and prolonged physical tasks and therefore may lead to injury, however from a performance perspective, relation between endurance efficient core muscles and optimal balance control has not been well-known. The purpose of this study was to examine the relationship of trunk muscle endurance and static balance. Methods Fifty male students inhabitant of Tehran university dormitory (age 23.9±2.4, height 173.0±4.5 weight 70.7±6.3) took part in the study. Trunk muscle endurance was assessed using Sørensen test of trunk extensor endurance, trunk flexor endurance test, side bridge endurance test and static balance was measured using single-limb stance test. A multiple linear regression analysis was applied to test if the trunk muscle endurance measures significantly predicted the static balance. Results There were positive correlations between static balance level and trunk flexor, extensor and lateral endurance measures (Pearson correlation test, r=0.80 and P<0.001; r=0.71 and P<0.001; r=0.84 and P<0.001, respectively). According to multiple regression analysis for variables predicting static balance, the linear combination of trunk muscle endurance measures was significantly related to the static balance (F (3,46) = 66.60, P<0.001). Endurance of trunk flexor, extensor and lateral muscles were significantly associated with the static balance level. The regression model which included these factors had the sample multiple correlation coefficient of 0.902, indicating that approximately 81% of the variance of the static balance is explained by the model. Conclusion There is a significant relationship between trunk muscle endurance and static balance. PMID:24800004

Coordinated, multi-joint, fatigue-resistant feline stance produced with intrafascicular hind limb nerve stimulation.

PubMed

Normann, R A; Dowden, B R; Frankel, M A; Wilder, A M; Hiatt, S D; Ledbetter, N M; Warren, D A; Clark, G A

2012-04-01

The production of graceful skeletal movements requires coordinated activation of multiple muscles that produce torques around multiple joints. The work described herein is focused on one such movement, stance, that requires coordinated activation of extensor muscles acting around the hip, knee and ankle joints. The forces evoked in these muscles by external stimulation all have a complex dependence on muscle length and shortening velocities, and some of these muscles are biarticular. In order to recreate sit-to-stand maneuvers in the anesthetized feline, we excited the hind limb musculature using intrafascicular multielectrode stimulation (IFMS) of the muscular branch of the sciatic nerve, the femoral nerve and the main branch of the sciatic nerve. Stimulation was achieved with either acutely or chronically implanted Utah Slanted Electrode Arrays (USEAs) via subsets of electrodes (1) that activated motor units in the extensor muscles of the hip, knee and ankle joints, (2) that were able to evoke large extension forces and (3) that manifested minimal coactivation of the targeted motor units. Three hind limb force-generation strategies were investigated, including sequential activation of independent motor units to increase force, and interleaved or simultaneous IFMS of three sets of six or more USEA electrodes that excited the hip, knee and ankle extensors. All force-generation strategies evoked stance, but the interleaved IFMS strategy also reduced muscle fatigue produced by repeated sit-to-stand maneuvers compared with fatigue produced by simultaneous activation of different motor neuron pools. These results demonstrate the use of interleaved IFMS as a means to recreate coordinated, fatigue-resistant multi-joint muscle forces in the unilateral hind limb. This muscle activation paradigm could provide a promising neuroprosthetic approach for the restoration of sit-to-stand transitions in individuals who are paralyzed by spinal cord injury, stroke or disease.

Coordinated, multi-joint, fatigue-resistant feline stance produced with intrafascicular hind limb nerve stimulation

NASA Astrophysics Data System (ADS)

Normann, R. A.; Dowden, B. R.; Frankel, M. A.; Wilder, A. M.; Hiatt, S. D.; Ledbetter, N. M.; Warren, D. A.; Clark, G. A.

2012-04-01

The production of graceful skeletal movements requires coordinated activation of multiple muscles that produce torques around multiple joints. The work described herein is focused on one such movement, stance, that requires coordinated activation of extensor muscles acting around the hip, knee and ankle joints. The forces evoked in these muscles by external stimulation all have a complex dependence on muscle length and shortening velocities, and some of these muscles are biarticular. In order to recreate sit-to-stand maneuvers in the anesthetized feline, we excited the hind limb musculature using intrafascicular multielectrode stimulation (IFMS) of the muscular branch of the sciatic nerve, the femoral nerve and the main branch of the sciatic nerve. Stimulation was achieved with either acutely or chronically implanted Utah Slanted Electrode Arrays (USEAs) via subsets of electrodes (1) that activated motor units in the extensor muscles of the hip, knee and ankle joints, (2) that were able to evoke large extension forces and (3) that manifested minimal coactivation of the targeted motor units. Three hind limb force-generation strategies were investigated, including sequential activation of independent motor units to increase force, and interleaved or simultaneous IFMS of three sets of six or more USEA electrodes that excited the hip, knee and ankle extensors. All force-generation strategies evoked stance, but the interleaved IFMS strategy also reduced muscle fatigue produced by repeated sit-to-stand maneuvers compared with fatigue produced by simultaneous activation of different motor neuron pools. These results demonstrate the use of interleaved IFMS as a means to recreate coordinated, fatigue-resistant multi-joint muscle forces in the unilateral hind limb. This muscle activation paradigm could provide a promising neuroprosthetic approach for the restoration of sit-to-stand transitions in individuals who are paralyzed by spinal cord injury, stroke or disease.

Treatment with Riluzole Restores Normal Control of Soleus and Extensor Digitorum Longus Muscles during Locomotion in Adult Rats after Sciatic Nerve Crush at Birth

PubMed Central

Cabaj, Anna M.; Sławińska, Urszula

2017-01-01

The effects of sciatic nerve crush (SNC) and treatment with Riluzole on muscle activity during unrestrained locomotion were identified in an animal model by analysis of the EMG activity recorded from soleus (Sol) and extensor digitorum longus (EDL) muscles of both hindlimbs; in intact rats (IN) and in groups of rats treated for 14 days with saline (S) or Riluzole (R) after right limb nerve crush at the 1st (1S and 1R) or 2nd (2S and 2R) day after birth. Changes in the locomotor pattern of EMG activity were correlated with the numbers of survived motor units (MUs) identified in investigated muscles. S rats with 2–8 and 10–28 MUs that survived in Sol and EDL muscles respectively showed increases in the duration and duty factor of muscle EMG activity and a loss of correlation between the duty factors of muscle activity, and abnormal flexor-extensor co-activation 3 months after SNC. R rats with 5, 6 (Sol) and 15–29 MUs (EDL) developed almost normal EMG activity of both Sol and control EDL muscles, whereas EDL muscles with SNC showed a lack of recovery. R rats with 8 (Sol) and 23–33 (EDL) MUs developed almost normal EMG activities of all four muscles. A subgroup of S rats with a lack of recovery and R rats with almost complete recovery that had similar number of MUs (8 and 24–28 vs 8 and 23–26), showed that the number of MUs was not the only determinant of treatment effectiveness. The results demonstrated that rats with SNC failed to develop normal muscle activity due to malfunction of neuronal circuits attenuating EDL muscle activity during the stance phase, whereas treatment with Riluzole enabled almost normal EMG activity of Sol and EDL muscles during locomotor movement. PMID:28095499

Treatment with Riluzole Restores Normal Control of Soleus and Extensor Digitorum Longus Muscles during Locomotion in Adult Rats after Sciatic Nerve Crush at Birth.

PubMed

Zmysłowski, Wojciech; Cabaj, Anna M; Sławińska, Urszula

2017-01-01

The effects of sciatic nerve crush (SNC) and treatment with Riluzole on muscle activity during unrestrained locomotion were identified in an animal model by analysis of the EMG activity recorded from soleus (Sol) and extensor digitorum longus (EDL) muscles of both hindlimbs; in intact rats (IN) and in groups of rats treated for 14 days with saline (S) or Riluzole (R) after right limb nerve crush at the 1st (1S and 1R) or 2nd (2S and 2R) day after birth. Changes in the locomotor pattern of EMG activity were correlated with the numbers of survived motor units (MUs) identified in investigated muscles. S rats with 2-8 and 10-28 MUs that survived in Sol and EDL muscles respectively showed increases in the duration and duty factor of muscle EMG activity and a loss of correlation between the duty factors of muscle activity, and abnormal flexor-extensor co-activation 3 months after SNC. R rats with 5, 6 (Sol) and 15-29 MUs (EDL) developed almost normal EMG activity of both Sol and control EDL muscles, whereas EDL muscles with SNC showed a lack of recovery. R rats with 8 (Sol) and 23-33 (EDL) MUs developed almost normal EMG activities of all four muscles. A subgroup of S rats with a lack of recovery and R rats with almost complete recovery that had similar number of MUs (8 and 24-28 vs 8 and 23-26), showed that the number of MUs was not the only determinant of treatment effectiveness. The results demonstrated that rats with SNC failed to develop normal muscle activity due to malfunction of neuronal circuits attenuating EDL muscle activity during the stance phase, whereas treatment with Riluzole enabled almost normal EMG activity of Sol and EDL muscles during locomotor movement.

Leg extensor muscle strength, postural stability, and fear of falling after a 2-month home exercise program in women with severe knee joint osteoarthritis.

PubMed

Rätsepsoo, Monika; Gapeyeva, Helena; Sokk, Jelena; Ereline, Jaan; Haviko, Tiit; Pääsuke, Mati

2013-01-01

BACKGROUND AND OBJECTIVE. The aim of this study was to compare the leg extensor muscle strength, the postural stability, and the fear of falling in the women with severe knee joint osteoarthritis (OA) before and after a 2-month home exercise program (HEP). MATERIAL AND METHODS. In total, 17 women aged 46-72 years with late-stage knee joint OA scheduled for total knee arthroplasty participated in this study before and after the 2-month HEP with strengthening, stretching, balance, and step exercises. The isometric peak torque (PT) of the leg extensors and postural stability characteristics when standing on a firm or a foam surface for 30 seconds were recorded. The fear of falling and the pain intensity (VAS) were estimated. RESULTS. A significant increase in the PT and the PT-to-body weight (PT-to-BW) ratio of the involved leg as well as the bilateral PT and the PT-to-BW ratio was found after the 2-month HEP compared with the data before the HEP (P<0.05). The PT and the PT-to-BW ratio of the involved leg were significantly lower compared with the uninvolved leg before the HEP (P<0.05). The center of the pressure sway length (foam surface) decreased significantly after the HEP (P<0.05). Significant correlations were found between the PT of the involved leg and the bilateral PT and the fear of falling and between the PT of the involved leg and the postural sway (foam surface) before the HEP. CONCLUSIONS. After the 2-month HEP, the leg extensor muscle strength increased and the postural sway length on a foam surface decreased. The results indicate that the increased leg extensor muscle strength improves postural stability and diminishes the fear of falling in women with late-stage knee joint OA.

Adding muscle where you need it: non-uniform hypertrophy patterns in elite sprinters.

PubMed

Handsfield, G G; Knaus, K R; Fiorentino, N M; Meyer, C H; Hart, J M; Blemker, S S

2017-10-01

Sprint runners achieve much higher gait velocities and accelerations than average humans, due in part to large forces generated by their lower limb muscles. Various factors have been explored in the past to understand sprint biomechanics, but the distribution of muscle volumes in the lower limb has not been investigated in elite sprinters. In this study, we used non-Cartesian MRI to determine muscle sizes in vivo in a group of 15 NCAA Division I sprinters. Normalizing muscle sizes by body size, we compared sprinter muscles to non-sprinter muscles, calculated Z-scores to determine non-uniformly large muscles in sprinters, assessed bilateral symmetry, and assessed gender differences in sprinters' muscles. While limb musculature per height-mass was 22% greater in sprinters than in non-sprinters, individual muscles were not all uniformly larger. Hip- and knee-crossing muscles were significantly larger among sprinters (mean difference: 30%, range: 19-54%) but only one ankle-crossing muscle was significantly larger (tibialis posterior, 28%). Population-wide asymmetry was not significant in the sprint population but individual muscle asymmetries exceeded 15%. Gender differences in normalized muscle sizes were not significant. The results of this study suggest that non-uniform hypertrophy patterns, particularly large hip and knee flexors and extensors, are advantageous for fast sprinting. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Hip abductor, trunk extensor and ankle plantar flexor endurance in females with and without patellofemoral pain.

PubMed

Van Cant, Joachim; Pitance, Laurent; Feipel, Véronique

2017-01-01

Previous studies have reported strength deficit in hip abduction, extension and external rotation in females with patellofemoral pain (PFP) when compared with healthy control; however, there is conflicting evidence for a decrease in hip muscle endurance. Therefore, it seems important to evaluate hip muscle endurance in females with PFP. Moreover, trunk extensor and ankle plantar flexor endurance have not yet been evaluate in females with PFP. To compare hip abductor, trunk extensor and ankle plantar flexor endurance between females with and without PFP. Twenty females with PFP (mean age, 21.1 years) and 76 healthy females (mean age, 20.5 years) were recruited. Subject performed three endurance clinical tests: (1) The hip abductor isometric endurance test, (2) The Sorensen test and (3) The heel rise test. Group differences were assessed using an independent t tests, or Mann-Whitney U tests for non-normally distributed data. Subjects with PFP exhibited significantly lower hip abductor, trunk extensor and ankle plantar flexor endurance than healthy controls. On average, subjects with PFP had deficits of 16% in hip abduction, 14% in trunk extension and 26% in ankle plantar flexion. Females with PFP exhibited diminished hip abductor, trunk extensor and ankle plantar flexor endurance compared to healthy controls.

Ipsilateral Hip Abductor Weakness After Inversion Ankle Sprain

PubMed Central

Friel, Karen; McLean, Nancy; Myers, Christine; Caceres, Maria

2006-01-01

Context: Hip stability and strength are important for proper gait mechanics and foot position during heel strike. Objective: To determine the relationships between hip muscle strength and chronic ankle sprains and hip muscle strength and ankle range of motion. Design: Ex post facto design with the uninvolved limb serving as the control. Setting: Laboratory. Patients or Other Participants: A total of 23 subjects with unilateral chronic ankle sprain were recruited. Subjects had at least 2 ipsilateral ankle sprains and were bearing full weight, with the most recent injury occurring at least 3 months earlier. They were not undergoing formal or informal rehabilitation at the time of the study. Main Outcome Measure(s): We obtained goniometric measurements for all planes of motion at the ankle. Handheld dynamometry was used to assess the strength of the hip abductor and hip extensor muscles in both limbs. Results: Hip abductor muscle strength and plantar flexion were significantly less on the involved side than the uninvolved side (P < .001 in each case). Strength of the involved hip abductor and hip extensor muscles was significantly correlated (r = 0.539, P < .01). No significant difference was noted in hip extensor muscle strength between sides (P = .19). Conclusions: Our subjects with unilateral chronic ankle sprains had weaker hip abduction strength and less plantar-flexion range of motion on the involved sides. Clinicians should consider exercises to increase hip abduction strength when developing rehabilitation programs for patients with ankle sprains. PMID:16619098

Influence of muscle groups' activation on proximal femoral growth tendency.

PubMed

Yadav, Priti; Shefelbine, Sandra J; Pontén, Eva; Gutierrez-Farewik, Elena M

2017-12-01

Muscle and joint contact force influence stresses at the proximal growth plate of the femur and thus bone growth, affecting the neck shaft angle (NSA) and femoral anteversion (FA). This study aims to illustrate how different muscle groups' activation during gait affects NSA and FA development in able-bodied children. Subject-specific femur models were developed for three able-bodied children (ages 6, 7, and 11 years) using magnetic resonance images. Contributions of different muscle groups-hip flexors, hip extensors, hip adductors, hip abductors, and knee extensors-to overall hip contact force were computed. Specific growth rate for the growth plate was computed, and the growth was simulated in the principal stress direction at each element in the growth front. The predicted growth indicated decreased NSA and FA (of about [Formula: see text] over a four-month period) for able-bodied children. Hip abductors contributed the most, and hip adductors, the least, to growth rate. All muscles groups contributed to a decrease in predicted NSA ([Formula: see text]0.01[Formula: see text]-0.04[Formula: see text] and FA ([Formula: see text]0.004[Formula: see text]-[Formula: see text]), except hip extensors and hip adductors, which showed a tendency to increase the FA ([Formula: see text]0.004[Formula: see text]-[Formula: see text]). Understanding influences of different muscle groups on long bone growth tendency can help in treatment planning for growing children with affected gait.

Changes in trunk posture and muscle responses in standing during pregnancy and postpartum

PubMed Central

Biviá-Roig, Gemma; Lisón, Juan Francisco

2018-01-01

The aim of this study was to analyze the position of the lumbopelvic region and the muscle activation of erector spinae and biceps femoris muscles in a group of pregnant women in the third trimester. The hypothesis was that pregnancy-related biomechanical and morphological changes modify the position of the lumbopelvic region and the activation of extensor muscles. The position of the lumbar spine and pelvis in the sagittal plane, and the EMG activity of the erector spinae and biceps femoris muscles, were recorded during standing in 34 nulliparous and 34 pregnant women in the third trimester, and also two months after birth in the group of pregnant women. No significant differences in the position of the lumbar spine or pelvis between the group of pregnant women and nulliparous or postpartum were observed. A significant increase was observed in the EMG activity of the erector spinae (4.6% vs 2.4% and 2.1% in the nulliparous group and postpartum respectively) and the biceps femoris (3.4% vs 1.2% and 1.4%) in pregnant women compared to the other two groups (p <0.01). We conclude that pregnant women in the third trimester show no alterations in lumbopelvic position compared to nulliparous and postpartum women. However, there is an increase of the EMG activity of the trunk extensors. These results indicate that the extensor muscles of the trunk show, in static positions, adaptive responses to the increase of anterior loads during pregnancy. PMID:29584774

The Immediate Effect of Neuromuscular Joint Facilitation (NJF) Treatment on Hip Muscle Strength.

PubMed

Wang, Hongdan; Huo, Ming; Huang, Qiuchen; Li, Desheng; Maruyama, Hitoshi

2013-11-01

[Purpose] This study investigated the change in hip muscle strength of younger persons after neuromuscular joint facilitation (NJF) treatment. [Subjects] The subjects were 45 healthy young people, who were divided into two groups: a NJF group and a proprioceptive neuromuscular facilitation (PNF) group. The NJF group consisted of 21 subjects (11 males, 10 females), and the PNF group consisted of 24 subjects (11 males, 13 females). [Methods] Participants in the NJF group received NJF treatment. We measured the maximal flexor strength and the maximal extensor strength during isokinetic movement of the hip joint before and after intervention in both groups. The angular velocities used were 60°/sec and 180°/sec. [Results] The NJF group showed significant increases in the maximal flexor strength and the maximal extensor strength after the intervention at each angular velocity. In the PNF group, the maximal flexor strength of 60°/sec and the maximal extensor strength of 180°/sec were significant increases. [Conclusion] These results suggest that there is an immediate effect of NJF intervention on hip muscle strength.

Low back pain characterized by muscle resistance and occupational factors associated with nursing1

PubMed Central

Petersen, Rafael de Souza; Marziale, Maria Helena Palucci

2014-01-01

Objective to identify the occupational factors associated with low back pain using a surveillance tool and to characterize the low back pain by the resistance of the extensor muscles of the vertebral column among nursing professionals at an Intensive Care Unit. Methods Cross-sectional study. The workers answered a questionnaire about occupational factors and participated in a resistance test of the extensor muscles of the vertebral column. Associations were established through Student's T-test or Mann-Whitney's U-test and correlations using Pearson's test. Results Out of 48 participants, 32 (67%) suffered from low pain. For the resistance test, the subjects suffering from low back pain endured less time in comparison with asymptomatic subjects, but without significant differences (p=0.147). The duration of the pain episode showed a significant negative correlation (p=0.016) with the results of the resistance test though. The main factors identified as causes of low back pain were biomechanical and postural elements, conditions of the muscle structure and physical and organizational conditions. Conclusions the main occupational factors associated with the low back pain were the posture and the characteristics of the physical and organizational conditions. In addition, the extensor muscles of the column showed a trend towards lesser resistance for workers in pain. This evidence is important when considering prevention and treatment strategies. PMID:25029048

Multiple variations of the tendons of the anatomical snuffbox.

PubMed

Thwin, San San; Fazlin, Fazlin; Than, Myo

2014-01-01

Multiple tendons of the abductor pollicis longus (APL) in the anatomical snuffbox of the wrist can lead to the development of de Quervain's syndrome, which is caused by stenosing tenosynovitis. A cadaveric study was performed to establish the variations present in the tendons of the anatomical snuffbox in a Malaysian population, in the hope that this knowledge would aid clinical investigation and surgical treatment of de Quervain's tenosynovitis. Routine dissection of ten upper limbs was performed to determine the variations in the tendons of the anatomical snuffbox of the wrist. In all the dissected upper limbs, the APL tendon of the first extensor compartment was found to have several (3-14) tendon slips. The insertion of the APL tendon slips in all upper limbs were at the base of the first metacarpal bone, trapezium and fascia of the opponens pollicis muscle; however, in seven specimens, they were also found to be attached to the fleshy belly of the abductor pollicis brevis muscle. In two specimens, double tendons of the extensor pollicis longus located in the third extensor compartment were inserted into the capsule of the proximal interphalangeal joints before being joined to the extensor expansion. In two other specimens, the first extensor compartment had two osseofibrous tunnels divided by a septum that separated the APL tendon from the extensor pollicis brevis tendon. Multiple variations were found in the anatomical snuffbox region of the dissected upper limbs. Knowledge of these variations would be useful in interventional radiology and orthopaedic surgery.

Adaptive response of slow and fast skeletal muscle in the monkey to spaceflight

NASA Technical Reports Server (NTRS)

Bodine-Fowler, Sue

1996-01-01

Experiments were designed to determine the effects of the absence of weight support on hindlimb muscles of the monkey: an ankle flexor (tibialis anterior, TA), two ankle extensors (medical gastrocnemius, MG and soleus, SOL), and a knee extensor (vastus lateralis, VL). These experiments will be performed as part of the BION mission. The original project proposed to assess the effects of weightlessness in adult Rhesus monkeys which were to be flown on the Space Shuttle as part of SLS-3. Feasibility studies were carried out and a series of experiments were performed at NASA/Ames Research Center to assess the effects of a 21-day restraint period in the ESOP on muscle properties. The results of these studies are summarized.

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.

Muscle power failure in mobility-limited adults: preserved single muscle fibre function despite reduced whole muscle size, quality and neuromuscular activiation

USDA-ARS?s Scientific Manuscript database

This study investigated the physiological and gender determinants of the age-related loss of muscle power in 31 healthy middle-aged adults (aged 40-55 years), 28 healthy older adults (70-85 years) and 34 mobility-limited older adults (70-85 years). We hypothesized that leg extensor muscle power woul...

Asymmetry of Muscle Strength in Elite Athletes

ERIC Educational Resources Information Center

Drid, Patrik; Drapsin, Miodrag; Trivic, Tatjana; Lukac, Damir; Obadov, Slavko; Milosevic, Zoran

2009-01-01

"Study aim": To determine muscle strength variables in elite judoists and wrestlers since thigh muscle strength and bilaterally balanced flexor-to-extensor ratio minimise injury risk and are desirable for achieving sport successes. "Material and methods": Judoists, wrestlers and untrained subjects, 10 each, were subjected to isokinetic strength…

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.

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.

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.

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 fatigue on motor unit firing rate versus recruitment threshold relationships.

PubMed

Stock, Matt S; Beck, Travis W; Defreitas, Jason M

2012-01-01

The purpose of this study was to examine the influence of fatigue on the average firing rate versus recruitment threshold relationships for the vastus lateralis (VL) and vastus medialis. Nineteen subjects performed ten maximum voluntary contractions of the dominant leg extensors. Before and after this fatiguing protocol, the subjects performed a trapezoid isometric muscle action of the leg extensors, and bipolar surface electromyographic signals were detected from both muscles. These signals were then decomposed into individual motor unit action potential trains. For each subject and muscle, the relationship between average firing rate and recruitment threshold was examined using linear regression analyses. For the VL, the linear slope coefficients and y-intercepts for these relationships increased and decreased, respectively, after fatigue. For both muscles, many of the motor units decreased their firing rates. With fatigue, recruitment of higher threshold motor units resulted in an increase in slope for the VL. Copyright © 2011 Wiley Periodicals, Inc.

Embryonic development of the innervation of the locust extensor tibiae muscle by identified neurons: formation and elimination of inappropriate axon branches.

PubMed

Myers, C M; Whitington, P M; Ball, E E

1990-01-01

Intracellular dye fills have been used to reveal the pattern of embryonic growth of each of the four neurons which innervate the extensor tibiae muscle (ETi) of the hind leg of the locust. The growth cone of the slow extensor tibiae motoneuron (SETi), the first of the four neurons to leave the central nervous system, pioneers nerve 3 (N3). The fast extensor motoneuron (FETi), the next neuron to grow out, follows earlier outgrowing motoneurons into the periphery in nerve 5 (N5) and then rejoins SETi in N3. As it transfers from N5 to N3, it is transiently dye-coupled to the Tr1 pioneer neuron which spans the gap between the two nerves. It then follows SETi onto the ETi muscle in the femur. The common inhibitory neuron and the dorsal unpaired median neuron (DUMETi) follow SETi and FETi in nerves 3B2 and 5B1, respectively. SETi's growth cone requires almost twice as long to reach ETi as those of the three later motoneurons, all of which follow preexisting neural pathways. At least three of the four developing motoneurons form one or more axon branches not found in the adult. These branches may occur (1) at segmental boundaries; (2) where the nerve, which the growth cone is following, itself branches or the growth cone encounters another nerve; or (3) when the axon continues to grow beyond its target muscle. These findings contrast with the apparent absence of inappropriate axon branches in another developing locust neuromuscular system and during the innervation of zebrafish myotomes, but resemble in some ways the transient production of inappropriate axonal branches reported for embryonic leech motoneurons.

Effect of spaceflight on the isotonic contractile properties of single skeletal muscle fibers in the rhesus monkey

NASA Technical Reports Server (NTRS)

Fitts, R. H.; Romatowski, J. G.; Blaser, C.; De La Cruz, L.; Gettelman, G. J.; Widrick, J. J.

2000-01-01

Experiments from both Cosmos and Space Shuttle missions have shown weightlessness to result in a rapid decline in the mass and force of rat hindlimb extensor muscles. Additionally, despite an increased maximal shortening velocity, peak power was reduced in rat soleus muscle post-flight. In humans, declines in voluntary peak isometric ankle extensor torque ranging from 15-40% have been reported following long- and short-term spaceflight and prolonged bed rest. Complete understanding of the cellular events responsible for the fiber atrophy and the decline in force, as well as the development of effective countermeasures, will require detailed knowledge of how the physiological and biochemical processes of muscle function are altered by spaceflight. The specific purpose of this investigation was to determine the extent to which the isotonic contractile properties of the slow- and fast-twitch fiber types of the soleus and gastrocnemius muscles of rhesus monkeys (Macaca mulatta) were altered by a 14-day spaceflight.

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.

Ontogeny of the cranial musculature in Corydoras aeneus Callichthyidae, Siluriformes.

PubMed

Huysentruyt, F; Brunain, M; Adriaens, D

2009-11-01

A complete study of the early ontogeny of the cranial muscles of Corydoras aeneus (Callichthyidae) was undertaken and results were compared with those for the loricariid Ancistrus cf. triradiatus. This comparison reveals a high degree of similarity in the ontogeny of both species' cranial muscles. Both species lack a musculus protractor hyoidei, and the musculus intermandibularis posterior is divided into two different parts that have partly obtained a novel function (serving the lower lip) in A. cf. triradiatus. A similar increase in muscular complexity in this species is found in the dorsal constrictor of the hyoid muscle plate. This constrictor gives rise to the same muscles in both C. aeneus and A. cf. triradiatus, but in A. cf. triradiatus the musculus levator operculi later hypertrophies. In C. aeneus the musculus extensor tentaculi forms a single muscle diverging posteriorly, whereas in A. cf. triradiatus the musculus extensor tentaculi differentiates into two separate bundles. Also, a loricariid neoformation is present called the musculus levator tentaculi.

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.

Functional specialization and ontogenetic scaling of limb anatomy in Alligator mississippiensis

PubMed Central

Allen, Vivian; Elsey, Ruth M; Jones, Nicola; Wright, Jordon; Hutchinson, John R

2010-01-01

Crocodylians exhibit a fascinating diversity of terrestrial gaits and limb motions that remain poorly described and are of great importance to understanding their natural history and evolution. Their musculoskeletal anatomy is pivotal to this diversity and yet only qualitative studies of muscle-tendon unit anatomy exist. The relative masses and internal architecture (fascicle lengths and physiological cross-sectional areas) of muscles of the pectoral and pelvic limbs of American alligators (Alligator mississippiensis Daudin 1801) were recorded for an ontogenetic series of wild specimens (n = 15, body masses from 0.5 to 60 kg). The data were analysed by reduced major axis regression to determine scaling relationships with body mass. Physiological cross-sectional areas and therefore muscle force-generating capacity were found to be greater in the extensor (anti-gravity) muscles of the pelvic limb than in the pectoral limb, reflecting how crocodylians differ from mammals in having greater loading of the hindlimbs than the forelimbs. Muscle masses and architecture were generally found to scale isometrically with body mass, suggesting an ontogenetic decrease in terrestrial athleticism. This concurs with the findings of previous studies showing ontogenetic decreases in limb bone length and the general scaling principle of a decline of strength : weight ratios with increasing size in animals. Exceptions to isometric scaling found included positive allometry in fascicle length for extensor musculature of both limbs, suggesting an ontogenetic increase in working range interpreted as increasing postural variability – in particular the major hip extensors – the interpretation of which is complicated by previous described ontogenetic increase of moment arms for these muscles. PMID:20148991

Effect of muscle length on strength and dexterity after stroke.

PubMed

Ada, L; Canning, C; Dwyer, T

2000-02-01

The effect of muscle length on strength and dexterity after stroke was investigated. The aim was to determine if poor function at a particular muscle length could be attributed solely to differential weakness at this joint angle or whether an additional problem of differential dexterity exists. This descriptive research study measured elbow flexor and extensor strength as well as dexterity at three elbow joint angles: 30 degrees , 60 degrees and 90 degrees flexion. Dexterity was measured independently of strength. Fifteen (seven female, eight male) chronic stroke patients (mean age 67 years) who could actively flex and extend their affected elbow participated. Ten neurologically normal control subjects (mean age 67 years) acted as controls. Strength was measured as peak elbow flexor and extensor torque at three angles; and dexterity was measured as coherence for slow and fast tracking also at three angles. Dexterity was not affected by muscle length but strength was and this finding was the same for both stroke and controls. While the magnitude of the torque-angle curves was not significantly different between stroke and controls, the shape of torque-angle curves was altered after stroke so that both the elbow flexors (p < 0.05) and extensors (p < 0.05) tested weaker in the testing position where they were shortest. Since there was no differential loss of dexterity, it appears that differential loss of strength, especially in the shortened range, may explain the clinical observation of poorer function at one muscle length than another after stroke. Specific training to strengthen the muscles in these ranges is therefore of clinical importance for rehabilitation.

Electrophysiological appraisal of relative segmental motoneurone pool excitability in flexor and extensor.

PubMed Central

Fisher, M A

1978-01-01

F responses recorded from flexor and extensor muscles were analysed in 18 normal subjects and in 16 patients with motor system abnormalities. The prominence of the F responses was evaluated quantitatively by determining the persistence--that is, the fraction of measurable F responses which actually occur after a series of supramaximal stimuli--and average amplitude of the F responses. In the normal resting state, the data are consistent with the hypothesis that the "central excitatory states" of motoneurones is greater in the antigravity muscles than in those muscles not stretched by gravity. This pattern was disrupted in eight of the 16 patients with motor system abnormalities caused by central nervous system lesions. These changes reflect a clinically testable aspect of the pathophysiology of certain motor system disorders. PMID:690640

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.

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

Multiple variations of the tendons of the anatomical snuffbox

PubMed Central

Thwin, San San; Zaini, Fazlin; Than, Myo

2014-01-01

INTRODUCTION Multiple tendons of the abductor pollicis longus (APL) in the anatomical snuffbox of the wrist can lead to the development of de Quervain's syndrome, which is caused by stenosing tenosynovitis. A cadaveric study was performed to establish the variations present in the tendons of the anatomical snuffbox in a Malaysian population, in the hope that this knowledge would aid clinical investigation and surgical treatment of de Quervain's tenosynovitis. METHODS Routine dissection of ten upper limbs was performed to determine the variations in the tendons of the anatomical snuffbox of the wrist. RESULTS In all the dissected upper limbs, the APL tendon of the first extensor compartment was found to have several (3–14) tendon slips. The insertion of the APL tendon slips in all upper limbs were at the base of the first metacarpal bone, trapezium and fascia of the opponens pollicis muscle; however, in seven specimens, they were also found to be attached to the fleshy belly of the abductor pollicis brevis muscle. In two specimens, double tendons of the extensor pollicis longus located in the third extensor compartment were inserted into the capsule of the proximal interphalangeal joints before being joined to the extensor expansion. In two other specimens, the first extensor compartment had two osseofibrous tunnels divided by a septum that separated the APL tendon from the extensor pollicis brevis tendon. CONCLUSION Multiple variations were found in the anatomical snuffbox region of the dissected upper limbs. Knowledge of these variations would be useful in interventional radiology and orthopaedic surgery. PMID:24452976

Kinesthetic perception based on integration of motor imagery and afferent inputs from antagonistic muscles with tendon vibration.

PubMed

Shibata, E; Kaneko, F

2013-04-29

The perceptual integration of afferent inputs from two antagonistic muscles, or the perceptual integration of afferent input and motor imagery are related to the generation of a kinesthetic sensation. However, it has not been clarified how, or indeed whether, a kinesthetic perception would be generated by motor imagery if afferent inputs from two antagonistic muscles were simultaneously induced by tendon vibration. The purpose of this study was to investigate how a kinesthetic perception would be generated by motor imagery during co-vibration of the two antagonistic muscles at the same frequency. Healthy subjects participated in this experiment. Illusory movement was evoked by tendon vibration. Next, the subjects imaged wrist flexion movement simultaneously with tendon vibration. Wrist flexor and extensor muscles were vibrated according to 4 patterns such that the difference between the two vibration frequencies was zero. After each trial, the perceived movement sensations were quantified on the basis of the velocity and direction of the ipsilateral hand-tracking movements. When the difference in frequency applied to the wrist flexor and the extensor was 0Hz, no subjects perceived movements without motor imagery. However, during motor imagery, the flexion velocity of the perceived movement was higher than the flexion velocity without motor imagery. This study clarified that the afferent inputs from the muscle spindle interact with motor imagery, to evoke a kinesthetic perception, even when the difference in frequency applied to the wrist flexor and extensor was 0Hz. Furthermore, the kinesthetic perception resulting from integrations of vibration and motor imagery increased depending on the vibration frequency to the two antagonistic muscles. Copyright © 2013 Elsevier Ireland Ltd. 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.

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

Critical determinants of combined sprint and endurance performance: an integrative analysis from muscle fiber to the human body.

PubMed

van der Zwaard, Stephan; van der Laarse, Willem J; Weide, Guido; Bloemers, Frank W; Hofmijster, Mathijs J; Levels, Koen; Noordhof, Dionne A; de Koning, Jos J; de Ruiter, Cornelis J; Jaspers, Richard T

2018-04-01

Optimizing physical performance is a major goal in current physiology. However, basic understanding of combining high sprint and endurance performance is currently lacking. This study identifies critical determinants of combined sprint and endurance performance using multiple regression analyses of physiologic determinants at different biologic levels. Cyclists, including 6 international sprint, 8 team pursuit, and 14 road cyclists, completed a Wingate test and 15-km time trial to obtain sprint and endurance performance results, respectively. Performance was normalized to lean body mass 2/3 to eliminate the influence of body size. Performance determinants were obtained from whole-body oxygen consumption, blood sampling, knee-extensor maximal force, muscle oxygenation, whole-muscle morphology, and muscle fiber histochemistry of musculus vastus lateralis. Normalized sprint performance was explained by percentage of fast-type fibers and muscle volume ( R 2 = 0.65; P < 0.001) and normalized endurance performance by performance oxygen consumption ( V̇o 2 ), mean corpuscular hemoglobin concentration, and muscle oxygenation ( R 2 = 0.92; P < 0.001). Combined sprint and endurance performance was explained by gross efficiency, performance V̇o 2 , and likely by muscle volume and fascicle length ( P = 0.056; P = 0.059). High performance V̇o 2 related to a high oxidative capacity, high capillarization × myoglobin, and small physiologic cross-sectional area ( R 2 = 0.67; P < 0.001). Results suggest that fascicle length and capillarization are important targets for training to optimize sprint and endurance performance simultaneously.-Van der Zwaard, S., van der Laarse, W. J., Weide, G., Bloemers, F. W., Hofmijster, M. J., Levels, K., Noordhof, D. A., de Koning, J. J., de Ruiter, C. J., Jaspers, R. T. Critical determinants of combined sprint and endurance performance: an integrative analysis from muscle fiber to the human body.

Postmaximal contraction blood volume responses are blunted in obese and type 2 diabetic subjects in a muscle-specific manner

PubMed Central

Sanchez, Otto A.; Copenhaver, Elizabeth A.; Chance, Marti A.; Fowler, Michael J.; Towse, Theodore F.; Kent-Braun, Jane A.

2011-01-01

The purpose of this study was to determine whether there are differences in postisometric contraction blood volume and oxygenation responses among groups of type 2 diabetes mellitus (T2DM), obese, and lean individuals detectable using MRI. Eight T2DM patients were individually matched by age, sex, and race to non-T2DM individuals with similar body mass index (obese) and lean subjects. Functional MRI was performed using a dual-gradient-recalled echo, echo-planar imaging sequence with a repetition time of 1 s and at two echo times (TE = 6 and 46 ms). Data were acquired before, during, and after 10-s isometric dorsiflexion contractions performed at 50 and 100% of maximal voluntary contraction (MVC) force. MRI signal intensity (SI) changes from the tibialis anterior and extensor digitorum longus muscles were plotted as functions of time for each TE. From each time course, the difference between the minimum and the maximum postcontraction SI (ΔSI) were determined for TE = 6 ms (ΔSI6) and TE = 46 ms (ΔSI46), reflecting variations in blood volume and oxyhemoglobin saturation, respectively. Following 50% MVC contractions, the mean postcontraction ΔSI6 values were similar in the three groups. Following MVC only, and in the EDL muscle only, T2DM and obese participants had ∼56% lower ΔSI6 than the lean individuals. Also following MVC only, the ΔSI46 response in the EDL was lower in T2DM subjects than in lean individuals. These data suggest that skeletal muscle small vessel impairment occurs in T2DM and body mass index-matched subjects, in muscle-specific and contraction intensity-dependent manners. PMID:21572006

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ricafort, Juliet

A model was developed to determine the forces exerted by several flexor and extensor muscles of the human knee under static conditions. The following muscles were studied: the gastrocnemius, biceps femoris, semitendinosus, semimembranosus, and the set of quadricep muscles. The tibia and fibula were each modeled as rigid bodies; muscles were modeled by their functional lines of action in space. Assumptions based on previous data were used to resolve the indeterminacy.

Central and peripheral fatigue in knee and elbow extensor muscles after a long-distance cross-country ski race.

PubMed

Boccia, G; Dardanello, D; Zoppirolli, C; Bortolan, L; Cescon, C; Schneebeli, A; Vernillo, G; Schena, F; Rainoldi, A; Pellegrini, B

2017-09-01

Although elbow extensors (EE) have a great role in cross-country skiing (XC) propulsion, previous studies on neuromuscular fatigue in long-distance XC have investigated only knee extensor (KE) muscles. In order to investigate the origin and effects of fatigue induced by long-distance XC race, 16 well-trained XC skiers were tested before and after a 56-km classical technique race. Maximal voluntary isometric contraction (MVC) and rate of force development (RFD) were measured for both KE and EE. Furthermore, electrically evoked double twitch during MVC and at rest were measured. MVC decreased more in KE (-13%) than in EE (-6%, P = 0.016), whereas the peak RFD decreased only in EE (-26%, P = 0.02) but not in KE. The two muscles showed similar decrease in voluntary activation (KE -5.0%, EE -4.8%, P = 0.61) and of double twitch amplitude (KE -5%, EE -6%, P = 0.44). A long-distance XC race differently affected the neuromuscular function of lower and upper limbs muscles. Specifically, although the strength loss was greater for lower limbs, the capacity to produce force in short time was more affected in the upper limbs. Nevertheless, both KE and EE showed central and peripheral fatigue, suggesting that the origins of the strength impairments were multifactorial for the two muscles. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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...

Electrophysiological assessment of piano players' back extensor muscles on a regular piano bench and chair with back rest.

PubMed

Honarmand, Kavan; Minaskanian, Rafael; Maboudi, Seyed Ebrahim; Oskouei, Ali E

2018-01-01

[Purpose] Sitting position is the dominant position for a professional pianist. There are many static and dynamic forces which affect musculoskeletal system during sitting. In prolonged sitting, these forces are harmful. The aim of this study was to compare pianists' back extensor muscles activity during playing piano while sitting on a regular piano bench and a chair with back rest. [Subjects and Methods] Ten professional piano players (mean age 25.4 ± 5.28, 60% male, 40% female) performed similar tasks for 5 hours in two sessions: one session sitting on a regular piano bench and the other sitting on a chair with back rest. In each session, muscular activity was assessed in 3 ways: 1) recording surface electromyography of the back-extensor muscles at the beginning and end of each session, 2) isometric back extension test, and 3) musculoskeletal discomfort questionnaire. [Results] There were significantly lesser muscular activity, more ability to perform isometric back extension and better personal comfort while sitting on a chair with back rest. [Conclusion] Decreased muscular activity and perhaps fatigue during prolonged piano playing on a chair with back rest may reduce acquired musculoskeletal disorders amongst professional pianists.

Electrophysiological assessment of piano players’ back extensor muscles on a regular piano bench and chair with back rest

PubMed Central

Honarmand, Kavan; Minaskanian, Rafael; Maboudi, Seyed Ebrahim; Oskouei, Ali E.

2018-01-01

[Purpose] Sitting position is the dominant position for a professional pianist. There are many static and dynamic forces which affect musculoskeletal system during sitting. In prolonged sitting, these forces are harmful. The aim of this study was to compare pianists’ back extensor muscles activity during playing piano while sitting on a regular piano bench and a chair with back rest. [Subjects and Methods] Ten professional piano players (mean age 25.4 ± 5.28, 60% male, 40% female) performed similar tasks for 5 hours in two sessions: one session sitting on a regular piano bench and the other sitting on a chair with back rest. In each session, muscular activity was assessed in 3 ways: 1) recording surface electromyography of the back-extensor muscles at the beginning and end of each session, 2) isometric back extension test, and 3) musculoskeletal discomfort questionnaire. [Results] There were significantly lesser muscular activity, more ability to perform isometric back extension and better personal comfort while sitting on a chair with back rest. [Conclusion] Decreased muscular activity and perhaps fatigue during prolonged piano playing on a chair with back rest may reduce acquired musculoskeletal disorders amongst professional pianists. PMID:29410569

Comparison of physical fitness between rice farmers with and without chronic low back pain: a cross-sectional study.

PubMed

Taechasubamorn, Panada; Nopkesorn, Tawesak; Pannarunothai, Supasit

2010-12-01

To compare physical fitness between rice farmers with chronic low back pain (CLBP) and a healthy control group. Sixty-eight rice farmers with CLBP were matched according to age and sex with healthy farmers. All subjects underwent nine physical fitness tests for body composition, lifting capacity, static back extensor endurance, leg strength, static abdominal endurance, handgrip strength, hamstring flexibility, posterior leg and back muscles flexibility and abdominal flexibility. There was no significant difference between CLBP and healthy groups for all tests, except the static back extensor endurance. The back extensor endurance times of the CLBP group was significantly lower than that of the control group (p = 0.002). Static back extensor endurance is the deficient physical fitness in CLBP rice farmers. Back extensor endurance training should be emphasized in both prevention and rehabilitation programs.

Characterisation of myosin heavy chain gene variants in the fast and slow muscle fibres of gammarid amphipods.

PubMed

Whiteley, N M; Magnay, J L; McCleary, S J; Nia, S Khazraee; El Haj, A J; Rock, J

2010-10-01

Recent molecular work has revealed a large diversity of myosin heavy chain (MyHC) gene variants in the abdominal musculature of gammarid amphipods. An unusual truncated MyHC transcript from the loop 1 region (Variant A(3)) was consistently observed in multiple species and populations. The current study aimed to determine whether this MyHC variant is specific to a particular muscle fibre type, as a change in net charge to the loop 1 region of Variant A(3) could be functionally significant. The localisation of different fibre types within the abdominal musculature of several gammarid species revealed that the deep flexor and extensor muscles are fast-twitch muscle fibres. The dorsal superficial muscles were identified as slow fibres and the muscles extrinsic to the pleopods were identified as intermediate fibres. Amplification of loop 1 region mRNA from isolated superficial extensor and deep flexor muscles, and subsequent liquid chromatography and sequence analysis revealed that Variant A(3) was the primary MyHC variant in slow muscles, and the conserved A(1) sequence was the primary variant in fast muscles. The specific role of Variant A(3) in the slow muscles remains to be investigated. 2010 Elsevier Inc. All rights reserved.

A comparison of muscle activity in using touchscreen smartphone among young people with and without chronic neck-shoulder pain.

PubMed

Xie, Yanfei; Szeto, Grace P Y; Dai, Jie; Madeleine, Pascal

2016-01-01

This study aimed to examine differences in muscle activity between young people with and without neck-shoulder pain (n = 20 in each group), when they performed texting on a smartphone. Texting was compared between using both hands ('bilateral texting') and with only one hand ('unilateral texting'). Texting tasks were also compared with computer typing. Surface electromyography from three proximal postural muscles and four distal hand/thumb muscles on the right side was recorded. Compared with healthy controls, young people with neck-shoulder pain showed altered motor control consisting of higher muscle activity in the cervical erector spinae and upper trapezius when performing texting and typing tasks. Generally, unilateral texting was associated with higher muscle loading compared with bilateral texting especially in the forearm muscles. Compared with computer typing, smartphone texting was associated with higher activity in neck extensor and thumb muscles but lower activity in upper and lower trapezius as well as wrist extensors. This study demonstrated that symptomatic individuals had increased muscle activity in the neck–shoulder region when texting on a smartphone. Contemporary ergonomic guidelines should include advice on how to interact with handheld electronic devices to achieve a relaxed posture and reduced muscle load in order to reduce the risk of musculoskeletal disorders.

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.

A mouse anti-myostatin antibody increases muscle mass and improves muscle strength and contractility in the mdx mouse model of Duchenne muscular dystrophy and its humanized equivalent, domagrozumab (PF-06252616), increases muscle volume in cynomolgus monkeys.

PubMed

St Andre, Michael; Johnson, Mark; Bansal, Prashant N; Wellen, Jeremy; Robertson, Andrew; Opsahl, Alan; Burch, Peter M; Bialek, Peter; Morris, Carl; Owens, Jane

2017-11-09

The treatments currently approved for Duchenne muscular dystrophy (DMD), a progressive skeletal muscle wasting disease, address the needs of only a small proportion of patients resulting in an urgent need for therapies that benefit all patients regardless of the underlying mutation. Myostatin is a member of the transforming growth factor-β (TGF-β) family of ligands and is a negative regulator of skeletal muscle mass. Loss of myostatin has been shown to increase muscle mass and improve muscle function in both normal and dystrophic mice. Therefore, myostatin blockade via a specific antibody could ameliorate the muscle weakness in DMD patients by increasing skeletal muscle mass and function, thereby reducing patients' functional decline. A murine anti-myostatin antibody, mRK35, and its humanized analog, domagrozumab, were developed and their ability to inhibit several TGB-β ligands was measured using a cell-based Smad-activity reporter system. Normal and mdx mice were treated with mRK35 to examine the antibody's effect on body weight, lean mass, muscle weights, grip strength, ex vivo force production, and fiber size. The humanized analog (domagrozumab) was tested in non-human primates (NHPs) for changes in skeletal muscle mass and volume as well as target engagement via modulation of circulating myostatin. Both the murine and human antibodies are specific and potent inhibitors of myostatin and GDF11. mRK35 is able to increase body weight, lean mass, and muscle weights in normal mice. In mdx mice, mRK35 significantly increased body weight, muscle weights, grip strength, and ex vivo force production in the extensor digitorum longus (EDL) muscle. Further, tibialis anterior (TA) fiber size was significantly increased. NHPs treated with domagrozumab demonstrated a dose-dependent increase in lean mass and muscle volume and exhibited increased circulating levels of myostatin demonstrating target engagement. We demonstrated that the potent anti-myostatin antibody mRK35 and its clinical analog, domagrozumab, were able to induce muscle anabolic activity in both rodents, including the mdx mouse model of DMD, and non-human primates. A Phase 2, potentially registrational, clinical study with domagrozumab in DMD patients is currently underway.

Flexor and extensor muscle tone evaluated using the quantitative pendulum test in stroke and parkinsonian patients.

PubMed

Huang, Han-Wei; Ju, Ming-Shaung; Lin, Chou-Ching K

2016-05-01

The aim of this study was to evaluate the flexor and extensor muscle tone of the upper limbs in patients with spasticity or rigidity and to investigate the difference in hypertonia between spasticity and rigidity. The two experimental groups consisted of stroke patients and parkinsonian patients. The control group consisted of age and sex-matched normal subjects. Quantitative upper limb pendulum tests starting from both flexed and extended joint positions were conducted. System identification with a simple linear model was performed and model parameters were derived. The differences between the three groups and two starting positions were investigated by these model parameters and tested by two-way analysis of variance. In total, 57 subjects were recruited, including 22 controls, 14 stroke patients and 21 parkinsonian patients. While stiffness coefficient showed no difference among groups, the number of swings, relaxation index and damping coefficient showed changes suggesting significant hypertonia in the two patient groups. There was no difference between these two patient groups. The test starting from the extended position constantly manifested higher muscle tone in all three groups. In conclusion, the hypertonia of parkinsonian and stroke patients could not be differentiated by the modified pendulum test; the elbow extensors showed a higher muscle tone in both control and patient groups; and hypertonia of both parkinsonian and stroke patients is velocity dependent. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Comparison of Total and Intrinsic Muscle Stiffness Among Flexors and Extensors of the Ankle, Knee and Elbow

NASA Technical Reports Server (NTRS)

Lemoine, Sandra M.

1997-01-01

This study examined 3 methods that assessed muscle stiffness. Muscle stiffness has been quantified by tissue reactive force (transverse stiffness), vibration, and force (or torque) over displacement. Muscle stiffness also has two components: reflex (due to muscle sensor activity) and intrinsic (tonic firing of motor units, elastic nature of actin and myosin cross bridges, and connective tissue). This study compared three methods of measuring muscle stiffness of agonist-antagonist muscle pairs of the ankle, knee and elbow.

Comparative proteomic analysis of the aging soleus and extensor digitorum longus rat muscles using TMT labeling and mass spectrometry

PubMed Central

Chaves, Daniela F. S.; Carvalho, Paulo C.; Lima, Diogo B.; Nicastro, Humberto; Lorenzetti, Fábio M.; Filho, Mário S.; Hirabara, Sandro M.; Alves, Paulo H. M.; Moresco, James J.; Yates, John R.; Lancha, Antonio H.

2013-01-01

Sarcopenia describes an age-related decline in skeletal muscle mass, strength, and function that ultimately impairs metabolism, leads to poor balance, frequent falling, limited mobility, and a reduction in quality of life. Here we investigate the pathogenesis of sarcopenia through a proteomic shotgun approach. Briefly, we employed tandem mass tags (TMT) to quantitate and compare the protein profiles obtained from young versus old rat slow-twitch type of muscle (soleus) and a fast-twitch type of muscle (extensor digitorum longus, EDL). Our results disclose 3452 and 1848 proteins identified from soleus and EDL muscles samples of which 78 and 174 were found to be differentially expressed, respectively. In general, most of the proteins were structural related, involved in energy metabolism, oxidative stress, detoxification, or transport. Aging affected soleus and EDL muscles differently and several proteins were regulated in opposite ways. For example, pyruvate kinase had its expression and activity different in both soleus and EDL muscles. We were able to verify with existing literature many of our differentially expressed proteins as candidate aging biomarkers, and most importantly, disclose several new candidate biomarkers such as the glioblastoma amplified sequence (GAS), zero beta-globin, and prolargin. PMID:24001182

Comparative proteomic analysis of the aging soleus and extensor digitorum longus rat muscles using TMT labeling and mass spectrometry.

PubMed

Chaves, Daniela F S; Carvalho, Paulo C; Lima, Diogo B; Nicastro, Humberto; Lorenzeti, Fábio M; Siqueira-Filho, Mário; Hirabara, Sandro M; Alves, Paulo H M; Moresco, James J; Yates, John R; Lancha, Antonio H

2013-10-04

Sarcopenia describes an age-related decline in skeletal muscle mass, strength, and function that ultimately impairs metabolism and leads to poor balance, frequent falling, limited mobility, and a reduction in quality of life. Here we investigate the pathogenesis of sarcopenia through a proteomic shotgun approach. In brief, we employed tandem mass tags to quantitate and compare the protein profiles obtained from young versus old rat slow-twitch type of muscle (soleus) and a fast-twitch type of muscle (extensor digitorum longus, EDL). Our results disclose 3452 and 1848 proteins identified from soleus and EDL muscles samples, of which 78 and 174 were found to be differentially expressed, respectively. In general, most of the proteins were structural related and involved in energy metabolism, oxidative stress, detoxification, or transport. Aging affected soleus and EDL muscles differently, and several proteins were regulated in opposite ways. For example, pyruvate kinase had its expression and activity different in both soleus and EDL muscles. We were able to verify with existing literature many of our differentially expressed proteins as candidate aging biomarkers and, most importantly, disclose several new candidate biomarkers such as the glioblastoma amplified sequence, zero β-globin, and prolargin.

Kicking modality during erratic-dynamic and static condition effects the muscular co-activation of attacker.

PubMed

Kim, Tae-Whan; Lee, Sang-Cheol; Kil, Se-Kee; Kang, Sung-Chul; Lim, Young-Tae; Kim, Ki-Tae; Panday, Siddhartha Bikram

2017-05-01

The purpose of the study was to investigate the effect of different kicking modality, i.e., erratic-dynamic target (EDT) versus static target (ST) on the performance of the roundhouse kick in two groups of taekwondo athletes of different skill level. Three-dimensional analysis and surface electromyography (SEMG) analysis were performed on 12 (Group A: six sub-elite, Group B: six elite) athletes to investigate muscle co-activation pattern under two conditions, i.e., EDT versus ST. In the results, the muscle recruitment ratio of the agonistic muscles was higher for Group A, whereas Group B had higher recruitment ratio for antagonist muscles. Overall, the co-activation index (CI) of hip joints appeared higher in the extensors for Group A, whereas higher CI was observed in flexor muscles for Group B with comparatively higher CI during EDT condition than ST condition. Higher value of CI was observed in flexor muscles of the knee joints among Group A during EDT conditions, in contrast, higher CI in the extensor muscles was observed among Group B during ST conditions. In conclusion, the study confirmed that erratic-dynamic movements of target could change the movement coordination pattern to maintain the joint stability of participants.

Predicting the safe load on backpacker's arm using Lagrange multipliers method

NASA Astrophysics Data System (ADS)

Abdalla, Faisal Saleh; Rambely, Azmin Sham

2014-09-01

In this study, a technique has been suggested to reduce a backpack load by transmitting determined loads to the children arm. The purpose of this paper is to estimate school children arm muscles while load carriage as well as to determine the safe load can be carried at wrist while walking with backpack. A mathematical model, as three DOFs model, was investigated in the sagittal plane and Lagrange multipliers method (LMM) was utilized to minimize a quadratic objective function of muscle forces. The muscle forces were minimized with three different load conditions which are termed as 0-L=0 N, 1-L=21.95 N, and 2-L=43.9 N. The investigated muscles were estimated and compared to their maximum forces throughout the load conditions. Flexor and extensor muscles were estimated and the results showed that flexor muscles were active while extensor muscles showed inactivity. The estimated muscle forces were didn't exceed their maximum forces with 0-L and 1-L conditions whereas biceps and FCR muscles exceeded their maximum forces with 2-L condition. Consequently, 1-L condition is quiet safe to be carried by hand whereas 2-L condition is not. Thus to reduce the load in the backpack the transmitted load shouldn't exceed 1-L condition.

Correlation between muscle structure and filter characteristics of the muscle-joint system in three orthopteran insect species

PubMed

BÄSsler; BÜSchges; Meditz; BÄSsler

1996-01-01

In orthopteran insects, neural networks for joint control exhibit different characteristics due to behavioural specializations. We investigated whether these differences are generated purely by the neuronal networks, or whether characteristics of the muscles or joint architecture (muscle­joint system) are also involved in these behavioural specializations. We compared the properties of the muscle system moving the femur­tibia joint of the middle and hindleg of three species, Carausius morosus, Cuniculina impigra and Locusta migratoria. Four aspects were analysed for the tibial extensor muscle: (i) the frequency-dependence of motoneuronal activity in response to sinusoidal stimulation of the femoral chordotonal organ (fCO), (ii) the muscle structure, (iii) the innervation pattern of the muscle and (iv) the histochemical properties of the muscle fibres. These aspects were compared with the filter characteristics of the open-loop femur­tibia control system and of the muscle­joint system involved. Whereas in both phasmid species (Carausius morosus and Cuniculina impigra) the motoneuronal activity steadily increases with sinusoidal stimulation of the fCO in the frequency range 0.01­5 Hz, in Locusta migratoria there is a decrease in motoneuronal activity between 0.01 and 0.3 Hz. The muscle structure is basically similar in all three species, as the number of singly innervated muscle fibres (supplied by the fast extensor tibiae motor neurone, FETi) decreases from proximal to distal. The number of triply innervated fibres supplied by the FETi, the slow extensor tibiae (SETi) and the common inhibitor 1 (CI1) is maximal in the middle of the muscle, and the number of dually innervated fibres (supplied by SETi, CI1) increases from proximal to distal. Differences between the locust and the two phasmid species exist in the distal portion of the muscle. The phasmid extensor tibiae muscle contains a morphologically distinct bundle of muscle fibres, not present in the locust, which is mostly dually innervated and which is larger in Cuniculina impigra. Similar results were obtained for the histochemical characterisation of the muscle fibres as revealed from their staining for myofibrillar ATPase activity. The number of histochemically identified fast fibres decreased from proximal to distal, while the number of slow fibres increased. In Carausius morosus and Locusta migratoria, the percentage of slow fibres increased by up to 60­70 % at the distal end, while this increase was to almost 100 % in Cuniculina impigra. Apparently, the larger this distal region and the higher the percentage of slow, dually innervated fibres in it, the lower is the upper corner frequency (the stimulus frequency at which the joint control system produces a movement with 70 % of its maximal response amplitude) of the muscle­joint system. In summary, it appears that the upper corner frequency of the open-loop system in Locusta migratoria (<0.05 Hz) results at least in part from properties of the neuronal joint control network, but in Carausius morosus (0.5­1.0 Hz) and Cuniculina impigra (0.1­0.2 Hz) it results from the upper corner frequency of the muscle­joint system.

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.

A myostatin inhibitor (propeptide-Fc) increases muscle mass and muscle fiber size in aged mice but does not increase bone density or bone strength.

PubMed

Arounleut, Phonepasong; Bialek, Peter; Liang, Li-Fang; Upadhyay, Sunil; Fulzele, Sadanand; Johnson, Maribeth; Elsalanty, Mohammed; Isales, Carlos M; Hamrick, Mark W

2013-09-01

Loss of muscle and bone mass with age are significant contributors to falls and fractures among the elderly. Myostatin deficiency is associated with increased muscle mass in mice, dogs, cows, sheep and humans, and mice lacking myostatin have been observed to show increased bone density in the limb, spine, and jaw. Transgenic overexpression of myostatin propeptide, which binds to and inhibits the active myostatin ligand, also increases muscle mass and bone density in mice. We therefore sought to test the hypothesis that in vivo inhibition of myostatin using an injectable myostatin propeptide (GDF8 propeptide-Fc) would increase both muscle mass and bone density in aged (24 mo) mice. Male mice were injected weekly (20 mg/kg body weight) with recombinant myostatin propeptide-Fc (PRO) or vehicle (VEH; saline) for four weeks. There was no difference in body weight between the two groups at the end of the treatment period, but PRO treatment significantly increased mass of the tibialis anterior muscle (+ 7%) and increased muscle fiber diameter of the extensor digitorum longus (+ 16%) and soleus (+ 6%) muscles compared to VEH treatment. Bone volume relative to total volume (BV/TV) of the femur calculated by microCT did not differ significantly between PRO- and VEH-treated mice, and ultimate force (Fu), stiffness (S), toughness (U) measured from three-point bending tests also did not differ significantly between groups. Histomorphometric assays also revealed no differences in bone formation or resorption in response to PRO treatment. These data suggest that while developmental perturbation of myostatin signaling through either gene knockout or transgenic inhibition may alter both muscle and bone mass in mice, pharmacological inhibition of myostatin in aged mice has a more pronounced effect on skeletal muscle than on bone. © 2013. Published by Elsevier Inc. All rights reserved.

Fatigability of rat hindlimb muscle: associations between electromyogram and force during a fatigue test.

PubMed Central

Enoka, R M; Rankin, L L; Stuart, D G; Volz, K A

1989-01-01

1. An experimental protocol designed to assess fatigability in motor units (Burke, Levine, Tsairis & Zajac, 1973) has been applied to the whole muscles of anaesthetized adult rats, and the association between the electromyogram (EMG) and force was monitored over the course of the test. 2. Both test muscles (soleus and extensor digitorum longus) exhibited a wide range of fatigability, which was defined as the decline in isometric peak force at 6 min, such that the data could be separated into five levels of fatigability. Fatigue indices for each test muscle were distributed across three levels. 3. The EMG was quantified with four measures of amplitude, four of duration, and one interaction term (area). Correlation analyses indicated that the EMG was adequately represented by one measure of amplitude (absolute amplitude), one of duration (peak-to-peak duration) and area. The best single measure was area. 4. The EMG-force associations for soleus varied markedly among its three fatigability groups. In contrast, over the course of the test, all three extensor digitorum longus groups displayed qualitatively similar EMG-force associations. 5. Multiple regression analyses indicated that the EMG parameters were able to predict peak force better for extensor digitorum longus than for soleus. Furthermore, for both test muscle, the prediction was best for the most fatigable group. 6. The associations between EMG and force exhibited three patterns for the two test muscles and three levels of fatigability. These differences suggested variation in the mechanisms, related to both fibre-type composition and susceptibility to fatigue, that dictate the performance elicited by this particular stimulus regimen. The mechanisms seem to include both intracellular and transmission processes. Images Fig. 1 PMID:2778729

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.

Joint capsule attachment to the extensor carpi radialis brevis origin: an anatomical study with possible implications regarding the etiology of lateral epicondylitis.

PubMed

Nimura, Akimoto; Fujishiro, Hitomi; Wakabayashi, Yoshiaki; Imatani, Junya; Sugaya, Hiroyuki; Akita, Keiichi

2014-02-01

To identify the unique anatomical characteristic of the extensor carpi radialis brevis (ECRB) origin and points of differentiation from other extensors and to clarify the specific relationship of the ECRB to the underlying structures. We studied the origin of each extensor macroscopically for its muscular and tendinous parts; to identify the relationship between the ECRB origin and the deeper structures, we also examined the attachment of the joint capsule under the ECRB origin. The ECRB simply originated as a tendon without any muscle, whereas other extensors originated as a mixture of tendon and muscle. At the anterior part of the ECRB origin, the thin attachment of the joint capsule (average width, 3.3 mm) lay deep to the ECRB and was distinct. However, at the posterodistal portion, the joint capsule, annular ligament, and supinator were intermingled and originated as a single wide sheet from the humerus (average width, 10.7 mm). The anterior part of the ECRB origin was delicate, because the ECRB origin was purely tendinous, and the attachment of the articular capsule was thin compared with that of the posterodistal attachment. This thin attachment could be an initial factor leading to the development of lateral epicondylitis. The results of the current study may enhance magnetic resonance imaging understanding and may help clarify the etiology of the lateral epicondylitis. Copyright © 2014 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

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.

Increased muscular volume and cuticular specialisations enhance jump velocity in solitarious compared with gregarious desert locusts, Schistocerca gregaria.

PubMed

Rogers, Stephen M; Riley, Joanna; Brighton, Caroline; Sutton, Gregory P; Cullen, Darron A; Burrows, Malcolm

2016-03-01

The desert locust, Schistocerca gregaria, shows a strong phenotypic plasticity. It can develop, depending upon population density, into either a solitarious or gregarious phase that differs in many aspects of behaviour, physiology and morphology. Prominent amongst these differences is that solitarious locusts have proportionately longer hind femora than gregarious locusts. The hind femora contain the muscles and energy-storing cuticular structures that propel powerful jumps using a catapult-like mechanism. We show that solitarious locusts jump on average 23% faster and 27% further than gregarious locusts, and attribute this improved performance to three sources: first, a 17.5% increase in the relative volume of their hind femur, and hence muscle volume; second, a 24.3% decrease in the stiffness of the energy-storing semi-lunar processes of the distal femur; and third, a 4.5% decrease in the stiffness of the tendon of the extensor tibiae muscle. These differences mean that solitarious locusts can generate more power and store more energy in preparation for a jump than can gregarious locusts. This improved performance comes at a cost: solitarious locusts expend nearly twice the energy of gregarious locusts during a single jump and the muscular co-contraction that energises the cuticular springs takes twice as long. There is thus a trade-off between achieving maximum jump velocity in the solitarious phase against the ability to engage jumping rapidly and repeatedly in the gregarious phase. © 2016. Published by The Company of Biologists Ltd.

Comparison of muscle cross-sectional areas between weight lifters and wrestlers.

PubMed

Kanehisa, H; Ikegawa, S; Fukunaga, T

1998-05-01

The purpose of this study was to investigate the difference in the magnitude of muscular development between Olympic weight lifters and wrestlers through the measurements of fat-free mass (FFM) and limb muscle cross-sectional area (CSA). Subjects were college Olympic weight lifters (N = 34, age = 20.0 +/- 1.3 years, stature = 1.67 +/- 0.07 m, body mass = 70.1 +/- 10.2 kg, X +/- SD) and wrestlers (N = 33,20.3 +/- 1.2 years, 1.69 +/- 0.06 m, 71.0 +/- 1.8 kg) who had identical range of body mass. Body density and the CSAs of reciprocal muscle groups in the forearm, upper arm, lower leg and thigh were measured by underwater weighing and B-mode ultrasound methods, respectively. No significant difference was found in body density between the weight lifters (1.077 +/- 0.007 g x ml(-3)) and wrestlers (1.076 +/- 0.008 g x ml(-3)). Moreover, FFM and the CSA values of all muscle groups tested were similar in the two groups of weight-classified athletes, with an exception that the wrist flexor CSA was significantly larger in wrestlers than in weight lifters, and the knee extensor and thigh (extensors + flexors) CSAs were larger in weight lifters than in wrestlers. The total muscle CSA of every site was significantly correlated to FFM2/3 in the separate groups; r = 0.714 to 0.815 (p < 0.05) in weight lifters and r = 0.769 to 0.919 (p < 0.05) in wrestlers. While the CSA-to-FFM2/3 ratios of the upper arm and wrist flexor muscles were significantly higher in wrestlers than in weight lifters, those of the thigh and knee extensor muscles were higher in weight lifters than in wrestlers. Thus, the present results suggest that an event-related difference exists in the magnitude of limb muscle CSA between competitive weight lifters and wrestlers of similar FFM.

Digital image analysis of striated skeletal muscle tissue injury during reperfusion after induced ischemia

NASA Astrophysics Data System (ADS)

Rosero Salazar, Doris Haydee; Salazar Monsalve, Liliana

2015-01-01

Conditions such as surgical procedures or vascular diseases produce arterial ischemia and reperfusion injuries, which generate changes in peripheral tissues and organs, for instance, in striated skeletal muscle. To determine such changes, we conducted an experimental method in which 42 male Wistar rat were selected, to be undergone to tourniquet application on the right forelimb and left hind limb, to induce ischemia during one and three hours, followed by reperfusion periods starting at one hour and it was prolonged up to 32 days. Extensor carpi radialis longus and soleus respectively, were obtained to be processed for histochemical and morphometric analysis. By means of image processing and detection of regions of interest, variations of areas occupied by muscle fibers and intramuscular extracellular matrix (IM-ECM) throughout reperfusion were observed. In extensor carpi radialis longus, results shown reduction in the area occupied by muscle fibers; this change is significant between one hour and three hours ischemia followed by 16 hours, 48 hours and 32 days reperfusión (p˂0.005). To compare only periods of reperfusión that continued to three hours ischemia, were found significant differences, as well. For area occupied by IM-ECM, were identified increments in extensor carpi radialis longus by three hours ischemia and eight to 16 days reperfusion; in soleus, was observed difference by one hour ischemia with 42 hours reperfusion, and three hours ischemia followed by four days reperfusion (p˂0.005). Skeletal muscle develops adaptive changes in longer reperfusion, to deal with induced injury. Descriptions beyond 32 days reperfusion, can determine recovering normal pattern.

Smaller external notebook mice have different effects on posture and muscle activity.

PubMed

Oude Hengel, Karen M; Houwink, Annemieke; Odell, Dan; van Dieën, Jaap H; Dennerlein, Jack T

2008-07-01

Extensive computer mouse use is an identified risk factor for computer work-related musculoskeletal disorders; however, notebook computer mouse designs of varying sizes have not been formally evaluated but may affect biomechanical risk factors. Thirty adults performed a set of mouse tasks with five notebook mice, ranging in length from 75 to 105 mm and in width from 35 to 65 mm, and a reference desktop mouse. An electro-magnetic motion analysis system measured index finger (metacarpophalangeal joint), wrist and forearm postures, and surface electromyography measured muscle activity of three extensor muscles in the forearm and the first dorsal interosseus. The smallest notebook mice were found to promote less neutral postures (up to 3.2 degrees higher metacarpophalangeal joint adduction; 6.5 degrees higher metacarpophalangeal joint flexion, 2.3 degrees higher wrist extension) and higher muscle activity (up to 4.1% of maximum voluntary contraction higher wrist extensor muscle activity). Participants with smaller hands had overall more non-neutral postures than participants with larger hands (up to 5.6 degrees higher wrist extension and 5.9 degrees higher pronation); while participants with larger hands were more influenced by the smallest notebook mice (up to 3.6 degrees higher wrist extension and 5.5% of maximum voluntary contraction higher wrist extensor values). Self-reported ratings showed that while participants preferred smaller mice for portability; larger mice scored higher on comfort and usability. The smallest notebook mice increased the intensity of biomechanical exposures. Longer term mouse use could enhance these differences, having a potential impact on the prevention of work-related musculoskeletal disorders.

Sheep YAP1 temporal and spatial expression trend and its relation with MyHCs expression.

PubMed

Gao, W; Sun, W; Su, R; Lv, X Y; Wang, Q Z; Li, D; Musa, H H; Chen, L; Zhou, H; Xu, H S; Hua, W H

2016-04-04

RT-PCR was used to study the temporal and spatial pattern of Yes-associated protein 1 (YAP1) and myosin heavy chain (MyHC) expression in four different skeletal muscles (i.e., longissimus dorsi muscle, soleus muscle, gastrocnemius muscle, and extensor digitorum longus) and three growth stages (i.e., 2 days old, 2 and 6 months old) of Hu Sheep. The results showed that YAP1 was differentially expressed in skeletal muscles of sheep, that expression increased gradually with age, and that there were high levels of expression in the gastrocnemius muscle and lower levels in the longissimus dorsi muscle. MyHCI was expressed at high levels in the soleus muscle and at lower levels in the longissimus dorsi muscle. In contrast, MyHCIIA and MyHCIIX were expressed at high levels in the extensor digitorum longus and at lower levels in the soleus muscle. The expression of MyHCI and MyHCIIA decreased with increasing age while that of MyHCIIX increased. YAP1 expression was negatively correlated with MyHCII (P < 0.01) and positively correlated with MyHCIIX (P < 0.01) across all growth stages and skeletal muscle types studied. We speculate that after birth, the thicker muscle fiber diameter is associated with the high expression of MyHCIIX. Therefore, we conclude that YAP1 expression affects sheep muscle fiber development after birth and provides important genetic information for the selection candidate genes for sheep muscle growth.

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.

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

The extensor digitorum brevis: histological and histochemical aspects

PubMed Central

Jennekens, F. G. I.; Tomlinson, B. E.; Walton, J. N.

1972-01-01

Samples of the extensor digitorum brevis muscle (EDB) obtained at necropsy from 26 subjects without known neuromuscular disease were examined histologically and histochemically. In the two youngest subjects, aged 2 months and 8 years, a mosaic distribution of type I and type II fibres was present. From the second decade onwards, increasing with age, the mosaic pattern was gradually replaced by groups of type I and type II fibres and areas of grouped fibre atrophy appeared. It is suggested that these findings may be explained by a slow process of denervation and reinnervation. This process does not seem to occur to the same extent in three other distal limb muscles from which specimens were also examined. Images PMID:4260286

Sexual dimorphism of extensor carpi radialis muscle size, isometric force, relaxation rate and stamina during the breeding season of the frog Rana temporaria Linnaeus 1758.

PubMed

Navas, Carlos A; James, Rob S

2007-02-01

Mating success of individual male frogs within explosive breeding species can depend on their ability to compete for a mate and to hold onto that mate during amplexus. Such importance of amplexus has resulted in the evolution of sexual dimorphism in the morphology and contractile characteristics of the anuran forelimb muscles used during amplexus. The aims of our study were to use an explosive breeding frog (Rana temporaria) during the breeding season to compare extensor carpi radialis (ECR) muscle length, mass, isometric activation times, relaxation times, absolute force, relative force (stress) and fatigue between male and female frogs. We found that ECR muscle mass and length were greater (tenfold and 1.4-fold, respectively), absolute tetanic muscle force and relative tetanic force (stress) were greater (16-fold and 2.2-fold, respectively) and relaxation times were slower in males than in females. Male ECR muscles incompletely relaxed during fatigue tests and showed less fatigue than female muscles. These sex differences are likely to be beneficial to the male frogs in allowing them to produce relatively high absolute muscle forces for prolonged periods of time to hold onto their mate during amplexus.

Risk factors and clinical features of text message injuries.

PubMed

Sharan, Deepak; Ajeesh, P S

2012-01-01

Use of mobile phone and sending text message is a very common in today's life. While sending a text message the users need to use their thumb and other palm muscles extensively. The thumb most of the time adducted on the key pad of the mobile and use high force to type the letters. Studies in literature showed that text messaging has an adverse effect on musculoskeletal system of hand. But the extensive study on the type of disorders set in among the users who extensively use mobile phone for texting. This study aims at to evaluate risk factor and clinical feature of the MSD due to hand held devices. Twenty seven subjects participated in this study. Predefined protocols were used to evaluate type of MSD occurred among the subjects. The study revealed that development of tendinitis in extensor pollicis longus, myofascial pain syndrome (70.37%) of adductor pollicis, 1st interossei and extensor digitorum communis . Other associated problems diagnosed were thoracic outlet syndrome (51.85%), fibromyalgia syndrome (25.93%), hypothyroidism (7.41%), wrist tendinitis (14.81%) and De Quervain's syndrome (7.41%). It has been observed that the pathology were tendinitis of extensor pollicis longus, myofascial pain syndrome of thenar muscles and 1st interossei, extensor digitorum communis.

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.

[A case of hypothyroidism displaying "dropped head" syndrome].

PubMed

Furutani, Rikiya; Ishihara, Kenji; Miyazawa, Yumi; Suzuki, Yoshio; Shiota, Jun-Ichi; Kawamur, Mitsuru

2007-01-01

We describe a patient with hypothyroidism displaying "dropped head" syndrome. A 50-year-old man visited our clinic because he was unable to hold his head in the natural position. He had weakness and hypertrophy of the neck extensor muscles. Tendon reflexes were diminished or absent in all limbs. Mounding phenomena were observed in the bilateral upper extremities. Blood biochemical analysis revealed hypothyroidism, hyperlipidemia, and elevated levels of muscle-derived enzymes. Magnetic resonance imaging (MRI) of the neck demonstrated swelling and hyperintensity of the neck extensor muscles on T2-weighted images. The result of biopsy of the right biceps brachii muscle suggested mild atrophy of type 2 fibers. The diameters of the muscle fibers exhibited mild variation. No inflammatory changes were observed. We diagnosed hin as having "dropped head" syndrome due to hypothyroidism. Administration of thyroid hormone agent gradually improved his condition, and he became able to hold his head in the natural position. Levels of muscle-derived enzymes normalized and his hyperlipidemia remitted. Neck MRI also revealed improvement. Our findings suggest that hypothyroidism should be considered in the differential diagnosis of "dropped head" syndrome, although only a few cases like ours have been reported.

Tibial and fibular nerves evaluation using intraoperative electromyography in rats.

PubMed

Nepomuceno, André Coelho; Politani, Elisa Landucci; Silva, Eduardo Guandelini da; Salomone, Raquel; Longo, Marco Vinicius Losso; Salles, Alessandra Grassi; Faria, José Carlos Marques de; Gemperli, Rolf

2016-08-01

To evaluate a new model of intraoperative electromyographic (EMG) assessment of the tibial and fibular nerves, and its respectives motor units in rats. Eight Wistar rats underwent intraoperative EMG on both hind limbs at two different moments: week 0 and week 12. Supramaximal electrical stimulation applied on sciatic nerve, and compound muscle action potential recorded on the gastrocnemius muscle (GM) and the extensor digitorum longus muscle (EDLM) through electrodes at specifics points. Motor function assessment was performaced through Walking Track Test. Exposing the muscles and nerves for examination did not alter tibial (p=0.918) or fibular (p=0.877) function between the evaluation moments. Electromyography of the GM, innervated by the tibial nerve, revealed similar amplitude (p=0.069) and latency (p=0.256) at week 0 and at 12 weeks, creating a standard of normality. Meanwhile, electromyography of the EDLM, innervated by the fibular nerve, showed significant differences between the amplitudes (p=0.003) and latencies (p=0.021) at the two different moments of observation. Intraoperative electromyography determined and quantified gastrocnemius muscle motor unit integrity, innervated by tibial nerve. Although this study was not useful to, objectively, assess extensor digitorum longus muscle motor unit, innervated by fibular nerve.

Phasic-to-tonic shift in trunk muscle activity relative to walking during low-impact weight bearing exercise

NASA Astrophysics Data System (ADS)

Caplan, Nick; Gibbon, Karl; Hibbs, Angela; Evetts, Simon; Debuse, Dorothée

2014-11-01

The aim of this study was to investigate the influence of an exercise device, designed to improve the function of lumbopelvic muscles via low-impact weight-bearing exercise, on electromyographic (EMG) activity of lumbopelvic, including abdominal muscles. Surface EMG activity was collected from lumbar multifidus (LM), erector spinae (ES), internal oblique (IO), external oblique (EO) and rectus abdominis (RA) during overground walking (OW) and exercise device (EX) conditions. During walking, most muscles showed peaks in activity which were not seen during EX. Spinal extensors (LM, ES) were more active in EX. Internal oblique and RA were less active in EX. In EX, LM and ES were active for longer than during OW. Conversely, EO and RA were active for a shorter duration in EX than OW. The exercise device showed a phasic-to-tonic shift in activation of both local and global lumbopelvic muscles and promoted increased activation of spinal extensors in relation to walking. These features could make the exercise device a useful rehabilitative tool for populations with lumbopelvic muscle atrophy and dysfunction, including those recovering from deconditioning due to long-term bed rest and microgravity in astronauts.

Eccentric contractions disrupt FKBP12 content in mouse skeletal muscle

PubMed Central

Baumann, Cory W.; Rogers, Russell G.; Gahlot, Nidhi; Ingalls, Christopher P.

2014-01-01

Abstract Strength deficits associated with eccentric contraction‐induced muscle injury stem, in part, from impaired voltage‐gated sarcoplasmic reticulum (SR) Ca2+ release. FKBP12 is a 12‐kD immunophilin known to bind to the SR Ca2+ release channel (ryanodine receptor, RyR1) and plays an important role in excitation‐contraction coupling. To assess the effects of eccentric contractions on FKBP12 content, we measured anterior crural muscle (tibialis anterior [TA], extensor digitorum longus [EDL], extensor hallucis longus muscles) strength and FKBP12 content in pellet and supernatant fractions after centrifugation via immunoblotting from mice before and after a single bout of either 150 eccentric or concentric contractions. There were no changes in peak isometric torque or FKBP12 content in TA muscles after concentric contractions. However, FKBP12 content was reduced in the pelleted fraction immediately after eccentric contractions, and increased in the soluble protein fraction 3 day after injury induction. FKBP12 content was correlated (P = 0.025; R2= 0.38) to strength deficits immediately after injury induction. In summary, eccentric contraction‐induced muscle injury is associated with significant alterations in FKBP12 content after injury, and is correlated with changes in peak isometric torque. PMID:25347864

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.

Elbow joint adductor moment arm as an indicator of forelimb posture in extinct quadrupedal tetrapods

PubMed Central

Fujiwara, Shin-ichi; Hutchinson, John R.

2012-01-01

Forelimb posture has been a controversial aspect of reconstructing locomotor behaviour in extinct quadrupedal tetrapods. This is partly owing to the qualitative and subjective nature of typical methods, which focus on bony articulations that are often ambiguous and unvalidated postural indicators. Here we outline a new, quantitatively based forelimb posture index that is applicable to a majority of extant tetrapods. By determining the degree of elbow joint adduction/abduction mobility in several tetrapods, the carpal flexor muscles were determined to also play a role as elbow adductors. Such adduction may play a major role during the stance phase in sprawling postures. This role is different from those of upright/sagittal and sloth-like creeping postures, which, respectively, depend more on elbow extensors and flexors. Our measurements of elbow muscle moment arms in 318 extant tetrapod skeletons (Lissamphibia, Synapsida and Reptilia: 33 major clades and 263 genera) revealed that sprawling, sagittal and creeping tetrapods, respectively, emphasize elbow adductor, extensor and flexor muscles. Furthermore, scansorial and non-scansorial taxa, respectively, emphasize flexors and extensors. Thus, forelimb postures of extinct tetrapods can be qualitatively classified based on our quantitative index. Using this method, we find that Triceratops (Ceratopsidae), Anhanguera (Pterosauria) and desmostylian mammals are categorized as upright/sagittally locomoting taxa. PMID:22357261

Architectural properties of the neuromuscular compartments in selected forearm skeletal muscles

PubMed Central

Liu, An-Tang; Liu, Ben-Li; Lu, Li-Xuan; Chen, Gang; Yu, Da-Zhi; Zhu, Lie; Guo, Rong; Dang, Rui-Shan; Jiang, Hua

2014-01-01

The purposes f this study were to (i) explore the possibility of splitting the selected forearm muscles into separate compartments in human subjects; (ii) quantify the architectural properties of each neuromuscular compartment; and (iii) discuss the implication of these properties in split tendon transfer procedures. Twenty upper limbs from 10 fresh human cadavers were used in this study. Ten limbs of five cadavers were used for intramuscular nerve study by modified Sihler's staining technique, which confirmed the neuromuscular compartments. The other 10 limbs were included for architectural analysis of neuromuscular compartments. The architectural features of the compartments including muscle weight, muscle length, fiber length, pennation angle, and sarcomere length were determined. Physiological cross-sectional area and fiber length/muscle length ratio were calculated. Five of the selected forearm muscles were ideal candidates for splitting, including flexor carpi ulnaris, flexor carpi radials, extensor carpi radialis brevis, extensor carpi ulnaris and pronator teres. The humeral head of pronator teres contained the longest fiber length (6.23 ± 0.31 cm), and the radial compartment of extensor carpi ulnaris contained the shortest (2.90 ± 0.28 cm). The ulnar compartment of flexor carpi ulnaris had the largest physiological cross-sectional area (5.17 ± 0.59 cm2), and the ulnar head of pronator teres had the smallest (0.67 ± 0.06 cm2). Fiber length/muscle length ratios of the neuromuscular compartments were relatively low (average 0.27 ± 0.09, range 0.18–0.39) except for the ulnar head of pronator teres, which had the highest one (0.72 ± 0.05). Using modified Sihler's technique, this research demonstrated that each compartment of these selected forearm muscles has its own neurovascular supply after being split along its central tendon. Data of the architectural properties of each neuromuscular compartment provide insight into the ‘design’ of their functional capability. In addition to improving our understanding of muscle anatomy and function, elucidation of forearm neuromuscular compartments architecture may ultimately provide information useful for selection of muscle subdivisions used in tendon transfer. PMID:24836406

Time course of functional recovery during the first 3 mo after surgical transection and repair of nerves to the feline soleus and lateral gastrocnemius muscles.

PubMed

Gregor, Robert J; Maas, Huub; Bulgakova, Margarita A; Oliver, Alanna; English, Arthur W; Prilutsky, Boris I

2018-03-01

Locomotion outcomes after peripheral nerve injury and repair in cats have been described in the literature for the period immediately following the injury (muscle denervation period) and then again for an ensuing period of long-term recovery (at 3 mo and longer) resulting in muscle self-reinnervation. Little is known about the changes in muscle activity and walking mechanics during midrecovery, i.e., the early reinnervation period that takes place between 5 and 10 wk of recovery. Here, we investigated hindlimb mechanics and electromyogram (EMG) activity of ankle extensors in six cats during level and slope walking before and every 2 wk thereafter in a 14-wk period of recovery after the soleus (SO) and lateral gastrocnemius (LG) muscle nerves in one hindlimb were surgically transected and repaired. We found that the continued increase in SO and LG EMG magnitudes and corresponding changes in hindlimb mechanics coincided with the formation of neuromuscular synapses revealed in muscle biopsies. Throughout the recovery period, EMG magnitude of SO and LG during the stance phase and the duration of the stance-related activity were load dependent, similar to those in the intact synergistic medial gastrocnemius and plantaris. These results and the fact that EMG activity of ankle extensors and locomotor mechanics during level and upslope walking recovered 14 wk after nerve transection and repair suggest that loss of the stretch reflex in self-reinnervated muscles may be compensated by the recovered force-dependent feedback in self-reinnervated muscles, by increased central drive, and by increased gain in intermuscular motion-dependent pathways from intact ankle extensors. NEW & NOTEWORTHY This study provides new evidence that the timeline for functional recovery of gait after peripheral nerve injury and repair is consistent with the time required for neuromuscular junctions to form and muscles to reach preoperative tensions. Our findings suggest that a permanent loss of autogenic stretch reflex in self-reinnervated muscles may be compensated by recovered intermuscular force-dependent and oligosynaptic length-dependent feedback and central drive to regain adequate locomotor output capabilities during level and upslope walking.

Determination of cable parameters in skeletal muscle fibres during repetitive firing of action potentials.

PubMed

Riisager, Anders; Duehmke, Rudy; Nielsen, Ole Bækgaard; Huang, Christopher L; Pedersen, Thomas Holm

2014-10-15

Recent studies in rat muscle fibres show that repetitive firing of action potentials causes changes in fibre resting membrane conductance (Gm) that reflect regulation of ClC-1 Cl(-) and KATP K(+) ion channels. Methodologically, these findings were obtained by inserting two microelectrodes at close proximity in the same fibres enabling measurements of fibre input resistance (Rin) in between action potential trains. Since the fibre length constant (λ) could not be determined, however, the calculation of Gm relied on the assumptions that the specific cytosolic resistivity (Ri) and muscle fibre volume remained constant during the repeated action potential firing. Here we present a three-microelectrode technique that enables determinations of multiple cable parameters in action potential-firing fibres including Rin and λ as well as waveform and conduction velocities of fully propagating action potentials. It is shown that in both rat and mouse extensor digitorum longus (EDL) fibres, action potential firing leads to substantial changes in both muscle fibre volume and Ri. The analysis also showed, however, that regardless of these changes, rat and mouse EDL fibres both exhibited initial decreases in Gm that were eventually followed by a ∼3-fold, fully reversible increase in Gm after the firing of 1450-1800 action potentials. Using this three-electrode method we further show that the latter rise in Gm was closely associated with excitation failures and loss of action potential signal above -20 mV. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

Determination of cable parameters in skeletal muscle fibres during repetitive firing of action potentials

PubMed Central

Riisager, Anders; Duehmke, Rudy; Nielsen, Ole Bækgaard; Huang, Christopher L; Pedersen, Thomas Holm

2014-01-01

Recent studies in rat muscle fibres show that repetitive firing of action potentials causes changes in fibre resting membrane conductance (Gm) that reflect regulation of ClC-1 Cl− and KATP K+ ion channels. Methodologically, these findings were obtained by inserting two microelectrodes at close proximity in the same fibres enabling measurements of fibre input resistance (Rin) in between action potential trains. Since the fibre length constant (λ) could not be determined, however, the calculation of Gm relied on the assumptions that the specific cytosolic resistivity (Ri) and muscle fibre volume remained constant during the repeated action potential firing. Here we present a three-microelectrode technique that enables determinations of multiple cable parameters in action potential-firing fibres including Rin and λ as well as waveform and conduction velocities of fully propagating action potentials. It is shown that in both rat and mouse extensor digitorum longus (EDL) fibres, action potential firing leads to substantial changes in both muscle fibre volume and Ri. The analysis also showed, however, that regardless of these changes, rat and mouse EDL fibres both exhibited initial decreases in Gm that were eventually followed by a ∼3-fold, fully reversible increase in Gm after the firing of 1450–1800 action potentials. Using this three-electrode method we further show that the latter rise in Gm was closely associated with excitation failures and loss of action potential signal above −20 mV. PMID:25128573

Reconstruction of long digital extensor tendon by cranial tibial muscle fascia graft in a dog.

PubMed

Sabiza, Soroush; Khajeh, Ahmad; Naddaf, Hadi

2016-01-01

Tendon rupture in dogs is generally the result of a direct trauma. This report described the use of adjacent muscle autogenic fascial graft for reconstruction of distal rupture of long digital extensor tendon in a dog. A two-year-old male mix breed dog, was presented with a non-weight bearing lameness of the right hind limb and a deep rupture of lateral side of right tarsus. History taking revealed that this rupture appeared without any apparent cause, when walking around the farm, three days before. Radiography was done and no fracture was observed. Hyperextension of right tarsal joint compared to left limb was observed. Under general anesthesia, after dissections of the ruptured area, complete rupture of long digital extensor tendon was revealed. Then, we attempted to locate the edge of the tendon, however, the tendon length was shortened approximately 1 cm. Hence, a strip of 1 cm length from fascia of cranial tibial muscle was harvested to fill the defect. The graft was sutured to the two ends of tendon using locking loop pattern. Subcutaneous layers and the skin were sutured routinely. Ehmer sling bandage was applied to prevent weight bearing on the surgical region. Re-examination and phone contact with the owner eight weeks and six months postoperatively revealed a poor lameness and excellent function of the dog, respectively. It could be concluded that the fascia of adjacent muscles can be used as an autogenic graft for reconstruction of some tendon ruptures.

Reconstruction of long digital extensor tendon by cranial tibial muscle fascia graft in a dog

PubMed Central

Sabiza, Soroush; Khajeh, Ahmad; Naddaf, Hadi

2016-01-01

Tendon rupture in dogs is generally the result of a direct trauma. This report described the use of adjacent muscle autogenic fascial graft for reconstruction of distal rupture of long digital extensor tendon in a dog. A two-year-old male mix breed dog, was presented with a non-weight bearing lameness of the right hind limb and a deep rupture of lateral side of right tarsus. History taking revealed that this rupture appeared without any apparent cause, when walking around the farm, three days before. Radiography was done and no fracture was observed. Hyperextension of right tarsal joint compared to left limb was observed. Under general anesthesia, after dissections of the ruptured area, complete rupture of long digital extensor tendon was revealed. Then, we attempted to locate the edge of the tendon, however, the tendon length was shortened approximately 1 cm. Hence, a strip of 1 cm length from fascia of cranial tibial muscle was harvested to fill the defect. The graft was sutured to the two ends of tendon using locking loop pattern. Subcutaneous layers and the skin were sutured routinely. Ehmer sling bandage was applied to prevent weight bearing on the surgical region. Re-examination and phone contact with the owner eight weeks and six months postoperatively revealed a poor lameness and excellent function of the dog, respectively. It could be concluded that the fascia of adjacent muscles can be used as an autogenic graft for reconstruction of some tendon ruptures. PMID:27872726

Topsy-turvy locomotion: biomechanical specializations of the elbow in suspended quadrupeds reflect inverted gravitational constraints

PubMed Central

Fujiwara, Shin-ichi; Endo, Hideki; Hutchinson, John R

2011-01-01

Some tetrapods hang upside down from tree branches when moving horizontally. The ability to walk in quadrupedal suspension has been acquired independently in at least 14 mammalian lineages. During the stance (supportive) phase of quadrupedal suspension, the elbow joint flexor muscles (not the extensors as in upright vertebrates moving overground) are expected to contract to maintain the flexed limb posture. Therefore muscular control in inverted, suspended quadrupeds may require changes of muscle control, and even morphologies, to conditions opposite to those in upright animals. However, the relationships between musculoskeletal morphologies and elbow joint postures during the stance phase in suspended quadrupeds have not been investigated. Our analysis comparing postures and skeletal morphologies in Choloepus (Pilosa), Pteropus (Chiroptera), Nycticebus (Primates) and Cynocephalus (Dermoptera) revealed that the elbow joints of these animals were kept at flexed angles of 70–100 ° during the stance phase of quadrupedal suspension. At these joint angles the moment arms of the elbow joint flexors were roughly maximized, optimizing that component of antigravity support. Our additional measurements from various mammalian species show that suspended quadrupeds have relatively small extensor/flexor ratios in both muscle masses and maximum moment arms. Thus, in contrast to the pattern in normal terrestrial quadrupeds, suspended quadrupeds emphasize flexor over extensor muscles for body support. This condition has evolved independently multiple times, attendant with a loss or reduction of the ability to move in normal upright postures. PMID:21477151

Effects of Wearing a Compression Garment During Night Sleep on Recovery From High-Intensity Eccentric-Concentric Quadriceps Muscle Fatigue.

PubMed

Shimokochi, Yohei; Kuwano, Satoshi; Yamaguchi, Taichi; Abutani, Hiroyuki; Shima, Norihiro

2017-10-01

This study aimed to investigate the effects of wearing a compression garment (CG) during night sleep on muscle fatigue recovery after high-intensity eccentric and concentric knee extensor exercises. Seventeen male college students participated in 2 experimental sessions under CG and non-CG (NCG) wearing conditions. Before night sleep under CG or NCG wearing conditions, the subjects performed a fatiguing protocol consisting of 10 sets of 10 repetitions of maximal isokinetic eccentric and concentric knee extensor contractions, with 30-second rest intervals between the sets. Immediately before and after and 24 hours after the fatiguing protocol, maximum voluntary isometric contraction (MVIC) force for knee extensor muscles was measured; surface electromyographic data from the vastus medialis and rectus femoris were also measured. A 2-way repeated-measure analysis of variance followed by Bonferroni pairwise comparisons were used to analyze the differences in each variable. Paired-sample t-tests were used to analyze the mean differences between the conditions at the same time points for each variable. The MVIC 24 hours after the fatiguing protocol was approximately 10% greater in the CG than in the NCG condition (p = 0.033). Changes in the electromyographic variables over time did not significantly differ between the conditions. Thus, it was concluded that wearing a CG during night sleep may promote localized muscle fatigue recovery but does not influence neurological factors after the fatiguing exercise.

Beta2-adrenoceptor agonist fenoterol enhances functional repair of regenerating rat skeletal muscle after injury.

PubMed

Beitzel, Felice; Gregorevic, Paul; Ryall, James G; Plant, David R; Sillence, Martin N; Lynch, Gordon S

2004-04-01

Beta(2)-adrenoceptor agonists such as fenoterol are anabolic in skeletal muscle, and because they promote hypertrophy and improve force-producing capacity, they have potential application for enhancing muscle repair after injury. No previous studies have measured the beta(2)-adrenoceptor population in regenerating skeletal muscle or determined whether fenoterol can improve functional recovery in regenerating muscle after myotoxic injury. In the present study, the extensor digitorum longus (EDL) muscle of the right hindlimb of deeply anesthetized rats was injected with bupivacaine hydrochloride, which caused complete degeneration of all muscle fibers. The EDL muscle of the left hindlimb served as the uninjured control. Rats received either fenoterol (1.4 mg x kg(-1) x day(-1)) or an equal volume of saline for 2, 7, 14, or 21 days. Radioligand binding assays identified a approximately 3.5-fold increase in beta(2)-adrenoceptor density in regenerating muscle at 2 days postinjury. Isometric contractile properties of rat EDL muscles were measured in vitro. At 14 and 21 days postinjury, maximum force production (P(o)) of injured muscles from fenoterol-treated rats was 19 and 18% greater than from saline-treated rats, respectively, indicating more rapid restoration of function after injury. The increase in P(o) in fenoterol-treated rats was due to increases in muscle mass, fiber cross-sectional area, and protein content. These findings suggest a physiological role for beta(2)-adrenoceptor-mediated mechanisms in muscle regeneration and show clearly that fenoterol hastens recovery after injury, indicating its potential therapeutic application.

Is the relationship between increased knee muscle strength and improved physical function following exercise dependent on baseline physical function status?

PubMed

Hall, Michelle; Hinman, Rana S; van der Esch, Martin; van der Leeden, Marike; Kasza, Jessica; Wrigley, Tim V; Metcalf, Ben R; Dobson, Fiona; Bennell, Kim L

2017-12-08

Clinical guidelines recommend knee muscle strengthening exercises to improve physical function. However, the amount of knee muscle strength increase needed for clinically relevant improvements in physical function is unclear. Understanding how much increase in knee muscle strength is associated with improved physical function could assist clinicians in providing appropriate strength gain targets for their patients in order to optimise outcomes from exercise. The aim of this study was to investigate whether an increase in knee muscle strength is associated with improved self-reported physical function following exercise; and whether the relationship differs according to physical function status at baseline. Data from 100 participants with medial knee osteoarthritis enrolled in a 12-week randomised controlled trial comparing neuromuscular exercise to quadriceps strengthening exercise were pooled. Participants were categorised as having mild, moderate or severe physical dysfunction at baseline using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Associations between 12-week changes in physical function (dependent variable) and peak isometric knee extensor and flexor strength (independent variables) were evaluated with and without accounting for baseline physical function status and covariates using linear regression models. In covariate-adjusted models without accounting for baseline physical function, every 1-unit (Nm/kg) increase in knee extensor strength was associated with physical function improvement of 17 WOMAC units (95% confidence interval (CI) -29 to -5). When accounting for baseline severity of physical function, every 1-unit increase in knee extensor strength was associated with physical function improvement of 24 WOMAC units (95% CI -42 to -7) in participants with severe physical dysfunction. There were no associations between change in strength and change in physical function in participants with mild or moderate physical dysfunction at baseline. The association between change in knee flexor strength and change in physical function was not significant, irrespective of baseline function status. In patients with severe physical dysfunction, an increase in knee extensor strength and improved physical function were associated. ANZCTR 12610000660088 . Registered 12 August 2010.

Isokinetic trunk muscle performance in pre-teens and teens with and without back pain.

PubMed

Bernard, J-C; Boudokhane, S; Pujol, A; Chaléat-Valayer, E; Le Blay, G; Deceuninck, J

2014-02-01

To assess with an isokinetic dynamometer the force and endurance of the spinal flexor and extensor muscles in pre-teens or teens aged 11 to 13 and 14 to 16 years with and without low back pain (LBP). The control group and the LBP group were homogeneous in terms of age, weight, height and Body Mass Index (BMI). Assessment was carried out with the isokinetic dynamometer Cybex Norm®. The spinal flexors and extensors were explored concentrically at speeds of 60°, 90° and 120°/sec. The parameters chosen were: maximal moment of force (MMF), mean power (MP), total work (TW), F/E ratios (between the flexors and the extensors for the aforesaid parameters). In the LBP groups, clinical information (pain, extensibility of the spinal and sub-pelvic muscles, sports practice) and sagittal radiological data were all measured. While no significant difference in isokinetic performance was found between asymptomatic and LBP children in the 11-to-13-year-old group, the isokinetic performances of the LBP children were influenced positively by BMI value, number of hours of physical activity and radiologic value of the lumbar lordosis. As regards these pre-teens, assessment with an isokinetic dynamometer does not highlight muscle characteristics that might explain LBP occurrence. As regards the 14-to-16-year-old group, muscle strength has been found to be correlated with age. LBP teens were showed to have weaker extensors and stronger flexors than the healthy teens. It is with regard to this age group that assessment with an isokinetic dynamometer clearly yields interesting results. Since we have yet to standardize our evaluation criteria (working speed, number of trials…), it is difficult to compare our results with those reported in the literature. This is a preliminary study involving a relatively low number of patients. That said, given the fact that numerous parameters are connected with the age and height of the subjects, assessment with an isokinetic dynamometer can be constructively carried out from the age of 14. In order to further enhance understanding of this phenomenon, a longitudinal and comparative study of a larger group is needed. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Coexistence of twitch potentiation and tetanic force decline in rat hindlimb muscle

NASA Technical Reports Server (NTRS)

Rankin, Lucinda L.; Enoka, Roger M.; Volz, Kathryn A.; Stuart, Douglas G.

1988-01-01

The effect of whole-muscle fatigue on the isometric twitch was investigated in various hindlimb muscles of anesthetized rats, using an experimental protocol designed to assess the levels of fatigability in motor units. The results of EMG and force measurements revealed the existence of a linear relationship between fatigability and the magnitude of the twitch force following the fatigue test in both soleus and extensor digitorum longus muscles.

Protein metabolism in slow- and fast-twitch skeletal muscle during turpentine-induced inflammation.

PubMed

Muthny, Tomas; Kovarik, Miroslav; Sispera, Ludek; Tilser, Ivan; Holecek, Milan

2008-02-01

The aim of our study was to evaluate the differences in protein and amino acid metabolism after subcutaneous turpentine administration in the soleus muscle (SOL), predominantly composed of red fibres, and the extensor digitorum longus muscle (EDL) composed of white fibres. Young rats (40-60 g) were injected subcutaneously with 0.2 ml of turpentine oil/100 g body weight (inflammation) or with the same volume of saline solution (control). Twenty-four hours later SOL and EDL were dissected and incubated in modified Krebs-Heinseleit buffer to estimate total and myofibrillar proteolysis, chymotrypsin-like activity of proteasome (CHTLA), leucine oxidation, protein synthesis and amino acid release into the medium. The data obtained demonstrate that in intact rats, all parameters measured except protein synthesis are significantly higher in SOL than in EDL. In turpentine treated animals, CHTLA increased and protein synthesis decreased significantly more in EDL. Release of leucine was inhibited significantly more in SOL. We conclude that turpentine-induced inflammation affects more CHTLA, protein synthesis and leucine release in EDL compared to SOL.

Protein metabolism in slow- and fast-twitch skeletal muscle during turpentine-induced inflammation

PubMed Central

Muthny, Tomas; Kovarik, Miroslav; Sispera, Ludek; Tilser, Ivan; Holecek, Milan

2008-01-01

The aim of our study was to evaluate the differences in protein and amino acid metabolism after subcutaneous turpentine administration in the soleus muscle (SOL), predominantly composed of red fibres, and the extensor digitorum longus muscle (EDL) composed of white fibres. Young rats (40–60 g) were injected subcutaneously with 0.2 ml of turpentine oil/100 g body weight (inflammation) or with the same volume of saline solution (control). Twenty-four hours later SOL and EDL were dissected and incubated in modified Krebs–Heinseleit buffer to estimate total and myofibrillar proteolysis, chymotrypsin-like activity of proteasome (CHTLA), leucine oxidation, protein synthesis and amino acid release into the medium. The data obtained demonstrate that in intact rats, all parameters measured except protein synthesis are significantly higher in SOL than in EDL. In turpentine treated animals, CHTLA increased and protein synthesis decreased significantly more in EDL. Release of leucine was inhibited significantly more in SOL. We conclude that turpentine-induced inflammation affects more CHTLA, protein synthesis and leucine release in EDL compared to SOL. PMID:18197871

Forearm muscle oxygenation decreases with low levels of voluntary contraction

NASA Technical Reports Server (NTRS)

Murthy, G.; Kahan, N. J.; Hargens, A. R.; Rempel, D. M.

1997-01-01

The purpose of our investigation was to determine if the near infrared spectroscopy technique was sensitive to changes in tissue oxygenation at low levels of isometric contraction in the extensor carpi radialis brevis muscle. Nine subjects were seated with the right arm abducted to 45 degrees, elbow flexed to 85 degrees, forearm pronated 45 degrees, and wrist and forearm supported on an armrest throughout the protocol. Altered tissue oxygenation was measured noninvasively with near infrared spectroscopy. The near infrared spectroscopy probe was placed over the extensor carpi radialis brevis of the subject's right forearm and secured with an elastic wrap. After 1 minute of baseline measurements taken with the muscle relaxed, four different loads were applied just proximal to the metacarpophalangeal joint such that the subjects isometrically contracted the extensor carpi radialis brevis at 5, 10, 15, and 50% of the maximum voluntary contraction for 1 minute each. A 3-minute recovery period followed each level of contraction. At the end of the protocol, with the probe still in place, a value for ischemic tissue oxygenation was obtained for each subject. This value was considered the physiological zero and hence 0% tissue oxygenation. Mean tissue oxygenation (+/-SE) decreased from resting baseline (100% tissue oxygenation) to 89 +/- 4, 81 +/- 8, 78 +/- 8, and 47 +/- 8% at 5, 10, 15, and 50% of the maximum voluntary contraction, respectively. Tissue oxygenation levels at 10, 15, and 50% of the maximum voluntary contraction were significantly lower (p < 0.05) than the baseline value. Our results indicate that tissue oxygenation significantly decreases during brief, low levels of static muscle contraction and that near infrared spectroscopy is a sensitive technique for detecting deoxygenation noninvasively at low levels of forearm muscle contraction. Our findings have important implications in occupational medicine because oxygen depletion induced by low levels of muscle contraction may be directly linked to muscle fatigue.

Muscle "Building."

ERIC Educational Resources Information Center

Schlenker, Richard M.; And Others

1995-01-01

Describes the use of constructivism in teaching human anatomy. Provides directions for constructing arm-hand and leg-foot models that include extensor and flexor muscles and that are easily and cheaply constructed. Lists resources that provide ideas for using such models depending upon the curriculum implemented in a school or the course that is…

Comparison of Muscle Activation during Dominant Hand Wrist Flexion when Writing.

PubMed

Park, Soohee

2013-12-01

[Purpose] This study investigated the difference in muscle activation of the dominant upper extremity in right-handed and left-handed persons during writing. [Subjects] There were 36 subjects (16 left- handers/ 20 right- handers), and the study was conducted from 03/01/2012 to 30/3/2012. [Methods] Six electrodes were attached to the FCU (flexor carpi ulnaris), FCR (flexor carpi radialis), ECU (extensor carpi ulnaris), ECR (extensor carpi radialis), and both UT (upper trapezius) muscles. [Results] FCU muscle activation was 16.77±9.12% in left-handers and 10.29±4.13% (%MVIC) in right-handers. FCR muscle activation was 19.09±9.43% in left-handers and 10.64±5.03% in right-handers. In addition, the UT muscle activation on the writing hand side was 11.91±5.79% in left-handers and 1.66±1.19% in right-handers. [Conclusion] As a result of this study, it was discovered that left-handers used more wrist flexion in performance of the writing task with the dominant upper extremity than right-handers, and that the left-handers activated the wrist and shoulder muscles more than the right-handers. These results indicate a potential danger of musculoskeletal disease in left-hander.

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.

Evaluation of a dynamic arm support for seated and standing tasks: a laboratory study of electromyography and subjective feedback.

PubMed

Odell, Dan; Barr, Alan; Goldberg, Robert; Chung, Jeffrey; Rempel, David

2007-04-01

The goal of this study was to determine whether a new dynamic arm support system reduced shoulder and arm muscle load for seated and standing hand/ arm tasks. The new system provides support for both horizontal and vertical arm motion. A total of 11 participants performed ten tasks (five seated and five standing) both with and without the arm support. Outcomes were assessed with electromyography and subjective feedback. Muscle activity was measured over the dominant side supraspinatus, triceps and forearm extensor muscles. Significant (p < 0.01) reductions in static muscle activity were observed in one of ten tasks performed with the support device for the supraspinatus muscle, in five tasks for the triceps and in one task for forearm extensor muscles. Likewise, a significant improvement in subjective measures was reported with the support device for 'ease of task' for two of ten tasks, for 'forearm comfort' for three of ten tasks and for 'shoulder effort' for six of ten tasks. The results suggest that a dynamic forearm support may improve subjective comfort and reduce static muscle loads in the upper extremity for tasks that involve horizontal movement of the arms. For rapid motions, the value of the support is limited due to internal inertia and friction.

The Effects of Exercise on Pharmacokinetics and Pharmacodynamics of Physostigmine in Rats

DTIC Science & Technology

1991-02-15

combination of the two, regulate the biosynthetic and degradative enzymes of ACh in EDL (extensor digitorum longus) - fast muscle and soleus - slow muscle...and trained exercise on ChAT activities in fast and slow muscles of rat 100 17. Effect of subacute Phy (70 4g/kg, i.m.) and endurance training on...AChE activities in EDL and soleus muscles of rat 100 18. ChAT and AChE activities (% of control) in fast (EDL) and slow (soleus) muscle in subacute Phy

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

Self-reinnervated muscles lose autogenic length feedback, but intermuscular feedback can recover functional connectivity

PubMed Central

Prilutsky, Boris I.; Gregor, Robert J.; Abelew, Thomas A.; Nichols, T. Richard

2016-01-01

In this study, we sought to identify sensory circuitry responsible for motor deficits or compensatory adaptations after peripheral nerve cut and repair. Self-reinnervation of the ankle extensor muscles abolishes the stretch reflex and increases ankle yielding during downslope walking, but it remains unknown whether this finding generalizes to other muscle groups and whether muscles become completely deafferented. In decerebrate cats at least 19 wk after nerve cut and repair, we examined the influence of quadriceps (Q) muscles' self-reinnervation on autogenic length feedback, as well as intermuscular length and force feedback, among the primary extensor muscles in the cat hindlimb. Effects of gastrocnemius and soleus self-reinnervation on intermuscular circuitry were also evaluated. We found that autogenic length feedback was lost after Q self-reinnervation, indicating that loss of the stretch reflex appears to be a generalizable consequence of muscle self-reinnervation. However, intermuscular force and length feedback, evoked from self-reinnervated muscles, was preserved in most of the interactions evaluated with similar relative inhibitory or excitatory magnitudes. These data indicate that intermuscular spinal reflex circuitry has the ability to regain functional connectivity, but the restoration is not absolute. Explanations for the recovery of intermuscular feedback are discussed, based on identified mechanisms responsible for lost autogenic length feedback. Functional implications, due to permanent loss of autogenic length feedback and potential for compensatory adaptations from preserved intermuscular feedback, are discussed. PMID:27306676

Cellular and Morphological Alterations in the Vastus Lateralis Muscle as the Result of ACL Injury and Reconstruction.

PubMed

Noehren, Brian; Andersen, Anders; Hardy, Peter; Johnson, Darren L; Ireland, Mary Lloyd; Thompson, Katherine L; Damon, Bruce

2016-09-21

Individuals who have had an anterior cruciate ligament (ACL) tear and reconstruction continue to experience substantial knee extensor strength loss despite months of physical therapy. Identification of the alterations in muscle morphology and cellular composition are needed to understand potential mechanisms of muscle strength loss, initially as the result of the injury and subsequently from surgery and rehabilitation. We performed diffusion tensor imaging-magnetic resonance imaging and analyzed muscle biopsies from the vastus lateralis of both the affected and unaffected limbs before surgery and again from the reconstructed limb following the completion of rehabilitation. Immunohistochemistry was done to determine fiber type and size, Pax-7-positive (satellite) cells, and extracellular matrix (via wheat germ agglutinin straining). Using the diffusion tensor imaging data, the fiber tract length, pennation angle, and muscle volume were determined, yielding the physiological cross-sectional area (PCSA). Paired t tests were used to compare the effects of the injury between injured and uninjured limbs and the effects of surgery and rehabilitation within the injured limb. We found significant reductions before surgery in type-IIA muscle cross-sectional area (CSA; p = 0.03), extracellular matrix (p < 0.01), satellite cells per fiber (p < 0.01), pennation angle (p = 0.03), muscle volume (p = 0.02), and PCSA (p = 0.03) in the injured limb compared with the uninjured limb. Following surgery, these alterations in the injured limb persisted and the frequency of the IIA fiber type decreased significantly (p < 0.01) and that of the IIA/X hybrid fiber type increased significantly (p < 0.01). Significant and prolonged differences in muscle quality and morphology occurred after ACL injury and persisted despite reconstruction and extensive physical therapy. These results suggest the need to develop more effective early interventions following an ACL tear to prevent deleterious alterations within the quadriceps. Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.

High doses of anti-inflammatory drugs compromise muscle strength and hypertrophic adaptations to resistance training in young adults.

PubMed

Lilja, M; Mandić, M; Apró, W; Melin, M; Olsson, K; Rosenborg, S; Gustafsson, T; Lundberg, T R

2018-02-01

This study tested the hypothesis that high doses of anti-inflammatory drugs would attenuate the adaptive response to resistance training compared with low doses. Healthy men and women (aged 18-35 years) were randomly assigned to daily consumption of ibuprofen (IBU; 1200 mg; n = 15) or acetylsalicylic acid (ASA; 75 mg; n = 16) for 8 weeks. During this period, subjects completed supervised knee-extensor resistance training where one leg was subjected to training with maximal volitional effort in each repetition using a flywheel ergometer (FW), while the other leg performed conventional (work-matched across groups) weight-stack training (WS). Before and after training, muscle volume (MRI) and strength were assessed, and muscle biopsies were analysed for gene and protein expression of muscle growth regulators. The increase in m. quadriceps volume was similar between FW and WS, yet was (averaged across legs) greater in ASA (7.5%) compared with IBU (3.7%, group difference 34 cm 3 ; P = 0.029). In the WS leg, muscle strength improved similarly (11-20%) across groups. In the FW leg, increases (10-23%) in muscle strength were evident in both groups yet they were generally greater (interaction effects P < 0.05) for ASA compared with IBU. While our molecular analysis revealed several training effects, the only group interaction (P < 0.0001) arose from a downregulated mRNA expression of IL-6 in IBU. Maximal over-the-counter doses of ibuprofen attenuate strength and muscle hypertrophic adaptations to 8 weeks of resistance training in young adults. Thus, young individuals using resistance training to maximize muscle growth or strength should avoid excessive intake of anti-inflammatory drugs. © 2017 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

The role of propriospinal neuronal network in transmitting the alternating muscular activities of flexor and extensor in parkinsonian tremor.

PubMed

Hao, M; He, X; Lan, N

2012-01-01

It has been shown that normal cyclic movement of human arm and resting limb tremor in Parkinson's disease (PD) are associated with the oscillatory neuronal activities in different cerebral networks, which are transmitted to the antagonistic muscles via the same spinal pathway. There are mono-synaptic and multi-synaptic corticospinal pathways for conveying motor commands. This study investigates the plausible role of propriospinal neuronal (PN) network in the C3-C4 levels in multi-synaptic transmission of cortical commands for oscillatory movements. A PN network model is constructed based on known neurophysiological connections, and is hypothesized to achieve the conversion of cortical oscillations into alternating antagonistic muscle bursts. Simulations performed with a virtual arm (VA) model indicate that without the PN network, the alternating bursts of antagonistic muscle EMG could not be reliably generated, whereas with the PN network, the alternating pattern of bursts were naturally displayed in the three pairs of antagonist muscles. Thus, it is suggested that oscillations in the primary motor cortex (M1) of single and double tremor frequencies are processed at the PN network to compute the alternating burst pattern in the flexor and extensor muscles.

Ergonomic design and evaluation of the handle for an endoscopic dissector.

PubMed

Shimomura, Yoshihiro; Minowa, Keita; Kawahira, Hiroshi; Katsuura, Tetsuo

2016-05-01

The purpose of this study was to design an endoscopic dissector handle and objectively assess its usability. The handles were designed with increased contact area between the fingers and thumb and the eye rings, and the eye rings were modified to have a more perpendicular insertion angle to the finger midline. Four different handle models were compared, including a conventional product. Subjects performed dissection, exclusion, grasping, precision manipulation and precision handling tasks. Electromyography and subjective evaluations were measured. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. The activity of the first dorsal interosseous muscle was sometimes influenced by the shape of the other parts. The ergonomically designed endoscopic dissector handle used in this study achieved high usability. Medical instrument designs based on ergonomic concepts should be assessed with objective indices. Practitioner Summary: The endoscopic dissector handles were designed with increased contact area and more suitable insertion angle between the fingers and thumb and the eye rings. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability.

Comparison of isometric cervical flexor and isometric cervical extensor system exercises on patients with neuromuscular imbalance and cervical crossed syndrome associated forward head posture.

PubMed

Lee, Jaejin; Kim, Dohyeon; Yu, Kyunghoon; Cho, Youngki; You, Joshua H

2018-01-01

Isometric cervical flexor system exercise (ICF) and isometric cervical extensor system exercise (ICE) are cervical stabilization techniques that have been used to restore cervical crossed syndrome (CCS)-associated forward head posture. However, the therapeutic effects and underlying motor control mechanisms remain elusive. The purpose of present study was investigating the concurrent therapeutic effects of ICF and ICE on muscle size, muscle imbalance ratio, and muscle recruitment sequence using ultrasound imaging and electromyography. A total of 18 participants (7 females; age=24±4.0 years) with CCS associated with forward head posture underwent ICF and ICE. Paired t-test analysis was used for statistical analysis. Paired t-test analysis showed that sternocleidomastoid thickness was greater during ICF than ICE. Similarly, cross-sectional area and horizontal thickness of the longus colli were greater during ICE than ICF. The upper trapezius/lower trapezius muscle imbalance ratio and the pectoralis major/lower trapezius muscle imbalance ratio were significantly decreased during the application of ICE compared to ICF. These results provide compelling, mechanistic evidence as to how ICE is more beneficial for the restoration of neuromuscular imbalance than ICF in individuals with CCS.

Comprehensive analysis of titin protein isoform and alternative splicing in normal and mutant rats.

PubMed

Li, Shijun; Guo, Wei; Schmitt, Benjamin M; Greaser, Marion L

2012-04-01

Titin is a giant protein with multiple functions in cardiac and skeletal muscles. Rat cardiac titin undergoes developmental isoform transition from the neonatal 3.7 MDa N2BA isoform to primarily the adult 2.97 MDa N2B isoform. An autosomal dominant mutation dramatically altered this transformation. Titins from eight skeletal muscles: Tibialis Anterior (TA), Longissimus Dorsi (LD) and Gastrocnemius (GA), Extensor Digitorum Longus (ED), Soleus (SO), Psoas (PS), Extensor Oblique (EO), and Diaphram (DI) were characterized in wild type and in homozygous mutant (Hm) rats with a titin splicing defect. Results showed that the developmental reduction in titin size is eliminated in the mutant rat so that the titins in all investigated skeletal muscles remain large in the adult. The alternative splicing of titin mRNA was found repressed by this mutation, a result consistent with the large titin isoform in the mutant. The developmental pattern of titin mRNA alternative splicing differs between heart and skeletal muscles. The retention of intron 49 reveals a possible mechanism for the absence of the N2B unique region in the expressed titin protein of skeletal muscle. © 2011 Wiley Periodicals, Inc.

Reduction-oxidation state and protein degradation in skeletal muscles of growing rats

NASA Technical Reports Server (NTRS)

Fagan, Julie M.; Tischler, Marc E.

1986-01-01

The relationship between the NAD redox state and protein degradation during growth was studied in isolated soleus and extensor digitorum longus muscles of 4- to 14-week-old rats. As muscle size increased with age, protein breakdown slowed and the muscles became progressively more reduced as shown by higher ratios of lactate/pyruvate in incubated and fresh-frozen muscle. Correlations were strong between redox state of protein degradation, and muscle mass, and between redox state and protein degradation. This relationship may be important in the slowing of muscle breakdown that occurs with age.

Estimation of Muscle Force Based on Neural Drive in a Hemispheric Stroke Survivor.

PubMed

Dai, Chenyun; Zheng, Yang; Hu, Xiaogang

2018-01-01

Robotic assistant-based therapy holds great promise to improve the functional recovery of stroke survivors. Numerous neural-machine interface techniques have been used to decode the intended movement to control robotic systems for rehabilitation therapies. In this case report, we tested the feasibility of estimating finger extensor muscle forces of a stroke survivor, based on the decoded descending neural drive through population motoneuron discharge timings. Motoneuron discharge events were obtained by decomposing high-density surface electromyogram (sEMG) signals of the finger extensor muscle. The neural drive was extracted from the normalized frequency of the composite discharge of the motoneuron pool. The neural-drive-based estimation was also compared with the classic myoelectric-based estimation. Our results showed that the neural-drive-based approach can better predict the force output, quantified by lower estimation errors and higher correlations with the muscle force, compared with the myoelectric-based estimation. Our findings suggest that the neural-drive-based approach can potentially be used as a more robust interface signal for robotic therapies during the stroke rehabilitation.

Estimation of muscle response using three-dimensional musculoskeletal models before impact situation: a simulation study.

PubMed

Bae, Tae Soo; Loan, Peter; Choi, Kuiwon; Hong, Daehie; Mun, Mu Seong

2010-12-01

When car crash experiments are performed using cadavers or dummies, the active muscles' reaction on crash situations cannot be observed. The aim of this study is to estimate muscles' response of the major muscle groups using three-dimensional musculoskeletal model by dynamic simulations of low-speed sled-impact. The three-dimensional musculoskeletal models of eight subjects were developed, including 241 degrees of freedom and 86 muscles. The muscle parameters considering limb lengths and the force-generating properties of the muscles were redefined by optimization to fit for each subject. Kinematic data and external forces measured by motion tracking system and dynamometer were then input as boundary conditions. Through a least-squares optimization algorithm, active muscles' responses were calculated during inverse dynamic analysis tracking the motion of each subject. Electromyography for major muscles at elbow, knee, and ankle joints was measured to validate each model. For low-speed sled-impact crash, experiment and simulation with optimized and unoptimized muscle parameters were performed at 9.4 m/h and 10 m/h and muscle activities were compared among them. The muscle activities with optimized parameters were closer to experimental measurements than the results without optimization. In addition, the extensor muscle activities at knee, ankle, and elbow joint were found considerably at impact time, unlike previous studies using cadaver or dummies. This study demonstrated the need to optimize the muscle parameters to predict impact situation correctly in computational studies using musculoskeletal models. And to improve accuracy of analysis for car crash injury using humanlike dummies, muscle reflex function, major extensor muscles' response at elbow, knee, and ankle joints, should be considered.

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.

Inter-Tester Reliability and Precision of Manual Muscle Testing and Hand-Held Dynamometry in Lower Limb Muscles of Children with Spina Bifida

ERIC Educational Resources Information Center

Mahony, Kate; Hunt, Adrienne; Daley, Deborah; Sims, Susan; Adams, Roger

2009-01-01

Reliability and measurement precision of manual muscle testing (MMT) and hand-held dynamometry (HHD) were compared for children with spina bifida. Strength measures were obtained of the hip flexors, hip abductors, and knee extensors of 20 children (10 males, 10 females; mean age 9 years 10 months; range: 5 to 15 years) by two experienced physical…

Inferring muscle functional roles of the ostrich pelvic limb during walking and running using computer optimization.

PubMed

Rankin, Jeffery W; Rubenson, Jonas; Hutchinson, John R

2016-05-01

Owing to their cursorial background, ostriches (Struthio camelus) walk and run with high metabolic economy, can reach very fast running speeds and quickly execute cutting manoeuvres. These capabilities are believed to be a result of their ability to coordinate muscles to take advantage of specialized passive limb structures. This study aimed to infer the functional roles of ostrich pelvic limb muscles during gait. Existing gait data were combined with a newly developed musculoskeletal model to generate simulations of ostrich walking and running that predict muscle excitations, force and mechanical work. Consistent with previous avian electromyography studies, predicted excitation patterns showed that individual muscles tended to be excited primarily during only stance or swing. Work and force estimates show that ostrich gaits are partially hip-driven with the bi-articular hip-knee muscles driving stance mechanics. Conversely, the knee extensors acted as brakes, absorbing energy. The digital extensors generated large amounts of both negative and positive mechanical work, with increased magnitudes during running, providing further evidence that ostriches make extensive use of tendinous elastic energy storage to improve economy. The simulations also highlight the need to carefully consider non-muscular soft tissues that may play a role in ostrich gait. © 2016 The Authors.

Asymmetry of neck motion and activation of the cervical paraspinal muscles during prone neck extension in subjects with unilateral posterior neck pain.

PubMed

Park, Kyue-Nam; Kwon, Oh-Yun; Kim, Su-Jung; Kim, Si-Hyun

2017-01-01

Although unilateral posterior neck pain (UPNP) is more prevalent than central neck pain, little is known about how UPNP affects neck motion and the muscle activation pattern during prone neck extension. To investigate whether deviation in neck motion and asymmetry of activation of the bilateral cervical paraspinal muscles occur during prone neck extension in subjects with UPNP compared to subjects without UPNP. This study recruited 20 subjects with UPNP and 20 age- and sex-matched control subjects without such pain. Neck motion and muscle onset time during prone neck extension were measured using a three-dimensional motion-analysis system and surface electromyography. The deviation during prone neck extension was greater in the UPNP group than in the controls (p < 0.05). Compared with the controls, cervical extensor muscle activation in the UPNP group was significantly delayed on the painful side during prone neck extension (p < 0.05). Subjects with UPNP showed greater asymmetry of neck motion and muscle activation during prone neck extension compared with the controls. This suggests that UPNP has specific effects on neck motion asymmetry and the functions of the cervical extensors, triggering a need for specific evaluation and exercises in the management of patients with UPNP.

THE FUNCTIONAL ROLES OF MUSCLES DURING SLOPED WALKING

PubMed Central

Pickle, Nathaniel T.; Grabowski, Alena M.; Auyang, Arick G.; Silverman, Anne K.

2016-01-01

Sloped walking is biomechanically different from level-ground walking, as evidenced by changes in joint kinematics and kinetics. However, the changes in muscle functional roles underlying these altered movement patterns have not been established. In this study, we developed a total of 273 muscle-actuated simulations to assess muscle functional roles, quantified by induced body center-of-mass accelerations and trunk and leg power, during walking on slopes of 0°, ±3°, ±6°, and ±9° at 1.25 m/s. The soleus and gastrocnemius both provided greater forward acceleration of the body parallel to the slope at +9° compared to level ground (+126% and +66%, respectively). However, while the power delivered to the trunk by the soleus varied with slope, the magnitude of net power delivered to the trunk and ipsilateral leg by the biarticular gastrocnemius was similar across all slopes. At +9°, the hip extensors absorbed more power from the trunk (230% hamstrings, 140% gluteus maximus) and generated more power to both legs (200% hamstrings, 160% gluteus maximus) compared to level ground. At −9°, the knee extensors (rectus femoris and vasti) accelerated the body upward perpendicular to the slope at least 50% more and backward parallel to the slope twice as much as on level ground. In addition, the knee extensors absorbed greater amounts of power from the ipsilateral leg on greater declines to control descent. Future studies can use these results to develop targeted rehabilitation programs and assistive devices aimed at restoring sloped walking ability in impaired populations. PMID:27553849

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

Decreased Muscle Strength Relates to Self-Reported Stooping, Crouching, or Kneeling Difficulty in Older Adults

PubMed Central

Goldberg, Allon; Alexander, Neil B.

2010-01-01

Background Bending down and kneeling are fundamental tasks of daily living, yet nearly a quarter of older adults report having difficulty performing or being unable to perform these movements. Older adults with stooping, crouching, or kneeling (SCK) difficulty have demonstrated an increased fall risk. Strength (force-generating capacity) measures may be useful for determining both SCK difficulty and fall risk. Objective The purposes of this study were: (1) to examine muscle strength differences in older adults with and without SCK difficulty and (2) to examine the relative contributions of trunk and leg muscle strength to SCK difficulty. Design This was a cross-sectional observational study. Methods Community-dwelling older adults (age [X̅±SD]=75.5±6.0 years) with SCK difficulty (n=27) or without SCK difficulty (n=21) were tested for leg and trunk strength and functional mobility. Isometric strength at the trunk, hip, knee, and ankle also was normalized by body weight and height. Results Compared with older adults with no SCK difficulty, those with SCK difficulty had significant decreases in normalized trunk extensor, knee extensor, and ankle dorsiflexor and plantar-flexor strength. In 2 separate multivariate analyses, raw ankle plantar-flexor strength (odds ratio [OR]=0.97, 95% confidence interval [CI]=0.95–0.99) and normalized knee extensor strength (OR=0.61, 95% CI=0.44–0.82) were significantly associated with SCK difficulty. Stooping, crouching, and kneeling difficulty also correlated with measures of functional balance and falls. Limitations Although muscle groups that were key to rising from SCK were examined, there are other muscle groups that may contribute to safe SCK performance. Conclusions Decreased muscle strength, particularly when normalized for body size, predicts SCK difficulty. These data emphasize the importance of strength measurement at multiple levels in predicting self-reported functional impairment. PMID:19942678

Effects of chronic administration of clenbuterol on contractile properties and calcium homeostasis in rat extensor digitorum longus muscle.

PubMed

Sirvent, Pascal; Douillard, Aymerick; Galbes, Olivier; Ramonatxo, Christelle; Py, Guillaume; Candau, Robin; Lacampagne, Alain

2014-01-01

Clenbuterol, a β2-agonist, induces skeletal muscle hypertrophy and a shift from slow-oxidative to fast-glycolytic muscle fiber type profile. However, the cellular mechanisms of the effects of chronic clenbuterol administration on skeletal muscle are not completely understood. As the intracellular Ca2+ concentration must be finely regulated in many cellular processes, the aim of this study was to investigate the effects of chronic clenbuterol treatment on force, fatigue, intracellular calcium (Ca2+) homeostasis and Ca2+-dependent proteolysis in fast-twitch skeletal muscles (the extensor digitorum longus, EDL, muscle), as they are more sensitive to clenbuterol-induced hypertrophy. Male Wistar rats were chronically treated with 4 mg.kg-1 clenbuterol or saline vehicle (controls) for 21 days. Confocal microscopy was used to evaluate sarcoplasmic reticulum Ca2+ load, Ca2+-transient amplitude and Ca2+ spark properties. EDL muscles from clenbuterol-treated animals displayed hypertrophy, a shift from slow to fast fiber type profile and increased absolute force, while the relative force remained unchanged and resistance to fatigue decreased compared to control muscles from rats treated with saline vehicle. Compared to control animals, clenbuterol treatment decreased Ca2+-transient amplitude, Ca2+ spark amplitude and frequency and the sarcoplasmic reticulum Ca2+ load was markedly reduced. Conversely, calpain activity was increased by clenbuterol chronic treatment. These results indicate that chronic treatment with clenbuterol impairs Ca2+ homeostasis and this could contribute to the remodeling and functional impairment of fast-twitch skeletal muscle.

Intramuscular Electrical Stimulation for Muscle Activation of the Tibialis Anterior After Surgical Repair: A Case Report.

PubMed

Hollis, Sharon; McClure, Philip

2017-12-01

Background Loss of voluntary activation of musculature can result in muscle weakness. External neuromuscular stimulation can be utilized to improve voluntary activation but is often poorly tolerated because of pain associated with required stimulus level. Intramuscular electrical stimulation requires much lower voltage and may be better tolerated, and therefore more effective at restoring voluntary muscle activation. Case Description A 71-year-old man sustained a rupture of the distal attachment of the tibialis anterior tendon. Thirty-two weeks after surgical repair, there was no palpable or visible tension development in the muscle belly or tendon. Dorsiflexion was dependent on toe extensors. Electrical stimulation applied via a dry needling placement in the muscle belly was utilized to induce an isometric contraction. Outcomes Five sessions of intramuscular electrical stimulation were delivered. By day 4 (second visit), the patient was able to dorsiflex without prominent use of the extensor hallucis longus. By day 6 (third visit), active-range-of-motion dorsiflexion with toes flexed increased 20° (-10° to 10°). Eighteen days after the initial treatment, the patient walked without his previous high-step gait pattern, and the tibialis anterior muscle test improved to withstanding moderate resistance (manual muscle test score, 4/5). Discussion The rapid change in muscle function observed suggests that intramuscular electrical stimulation may facilitate voluntary muscle activation. Level of Evidence Therapy, level 5. J Orthop Sports Phys Ther 2017;47(12):965-969. Epub 15 Oct 2017. doi:10.2519/jospt.2017.7368.

Anatomy and histochemistry of spread-wing posture in birds. 3. Immunohistochemistry of flight muscles and the "shoulder lock" in albatrosses.

PubMed

Meyers, Ron A; Stakebake, Eric F

2005-01-01

As a postural behavior, gliding and soaring flight in birds requires less energy than flapping flight. Slow tonic and slow twitch muscle fibers are specialized for sustained contraction with high fatigue resistance and are typically found in muscles associated with posture. Albatrosses are the elite of avian gliders; as such, we wanted to learn how their musculoskeletal system enables them to maintain spread-wing posture for prolonged gliding bouts. We used dissection and immunohistochemistry to evaluate muscle function for gliding flight in Laysan and Black-footed albatrosses. Albatrosses possess a locking mechanism at the shoulder composed of a tendinous sheet that extends from origin to insertion throughout the length of the deep layer of the pectoralis muscle. This fascial "strut" passively maintains horizontal wing orientation during gliding and soaring flight. A number of muscles, which likely facilitate gliding posture, are composed exclusively of slow fibers. These include Mm. coracobrachialis cranialis, extensor metacarpi radialis dorsalis, and deep pectoralis. In addition, a number of other muscles, including triceps scapularis, triceps humeralis, supracoracoideus, and extensor metacarpi radialis ventralis, were found to have populations of slow fibers. We believe that this extensive suite of uniformly slow muscles is associated with sustained gliding and is unique to birds that glide and soar for extended periods. These findings suggest that albatrosses utilize a combination of slow muscle fibers and a rigid limiting tendon for maintaining a prolonged, gliding posture.

V1 and V2b interneurons secure the alternating flexor-extensor motor activity mice require for limbed locomotion

PubMed Central

Zhang, Jingming; Lanuza, Guillermo M.; Britz, Olivier; Wang, Zhi; Siembab, Valerie C.; Zhang, Ying; Velasquez, Tomoko; Alvarez, Francisco J.; Frank, Eric; Goulding, Martyn

2014-01-01

SUMMARY The reciprocal activation of flexor and extensor muscles constitutes the fundamental mechanism that tetrapod vertebrates use for locomotion and limb-driven reflex behaviors. This aspect of motor coordination is controlled by inhibitory neurons in the spinal cord; however, the identity of the spinal interneurons that serve this function is not known. Here we show that the production of an alternating flexor-extensor motor rhythm depends on the composite activities of two classes of ventrally-located inhibitory neurons, V1 and V2b interneurons (INs). Abrogating V1 and V2b IN-derived neurotransmission in the isolated spinal cord results in a synchronous pattern of L2 flexor-related and L5 extensor-related locomotor activity. Mice lacking V1 and V2b inhibition are unable to articulate their limb joints and display marked deficits in limb-driven reflex movements. Taken together, these findings identify V1- and V2b-derived neurons as the core interneuronal components of the limb central pattern generator (CPG) that coordinate flexor-extensor motor activity. PMID:24698273

Fibrillation potentials, positive sharp waves and fasciculation in the intrinsic muscles of the foot in healthy subjects.

PubMed Central

Falck, B; Alaranta, H

1983-01-01

The extensor digitorum brevis and abductor digiti minimi muscles were examined bilaterally with electromyography in 53 healthy subjects. In 72% of the subjects either fibrillation potentials, positive sharp waves or fasciculation was seen in at least one muscle examined. These slight, usually symmetric neuropathic signs are believed to be associated with normal aging and to some extent also with external trauma to the nerves and muscles in the distal parts of the foot. PMID:6886709

Insulin effect on amino acid uptake by unloaded rat hindlimb muscles

NASA Technical Reports Server (NTRS)

Jaspers, S. R.; Tischler, M. E.

1988-01-01

The effect of insulin on the uptake of alpha-amino-isobutyric acid (AIB) by unloaded rat hindlimb muscles was investigated using soleus and extensor digitorum longus (EDL) muscles from intact and adrenalectomized (ADX) rats that were tail-casted for six days. It was found that, at insulin levels above 0.00001 units/ml, the in vitro rate of AIB uptake by muscles from intact animals was stimulated more in the weight bearing muscles than in unloaded ones. In ADX animals, this differential response to insulin was abolished.

Clenbuterol, a beta(2)-agonist, retards atrophy in denervated muscles

NASA Technical Reports Server (NTRS)

Zeman, Richard J.; Ludemann, Robert; Etlinger, Joseph D.

1987-01-01

The effects of a beta(2) agonist, clenbuterol, on the protein content as well as on the contractile strength and the muscle fiber cross-sectional area of various denervated muscles from rats were investigated. It was found that denervated soleus, anterior tibialis, and gastrocnemius muscles, but not the extensor digitorum longus, of rats treated for 2-3 weeks with clenbuterol contained 95-110 percent more protein than denervated controls. The twofold difference in the protein content of denervated solei was paralleled by similar changes in contractile strength and muscle fiber cross-sectional area.

High-intensity aerobic interval training can lead to improvement in skeletal muscle power among in-hospital patients with advanced heart failure.

PubMed

Taya, Masanobu; Amiya, Eisuke; Hatano, Masaru; Maki, Hisataka; Nitta, Daisuke; Saito, Akihito; Tsuji, Masaki; Hosoya, Yumiko; Minatsuki, Shun; Nakayama, Atsuko; Fujiwara, Takayuki; Konishi, Yuto; Yokota, Kazuhiko; Watanabe, Masafumi; Morita, Hiroyuki; Haga, Nobuhiko; Komuro, Issei

2018-01-15

This study investigated the effectiveness and safety of interval training during in-hospital treatment of patients with advanced heart failure. Twenty-four consecutive patients with advanced symptomatic heart failure who were referred for cardiac transplant evaluation were recruited. After performing aerobic exercise for approximate intensity, high-intensity interval training (HIIT) was performed. The protocol consisted of 3 or 4 sessions of 1-min high-intensity exercise aimed at 80% of peak VO 2 or 80% heart rate reserve, followed by 4-min recovery periods of low intensity. In addition to the necessary laboratory data, hand grip strength and knee extensor strength were evaluated at the start of exercise training and both at the start and the end of HIIT. Knee extensor strength was standardized by body weight. The BNP level at the start of exercise training was 432 (812) pg/mL and it significantly decreased to 254 (400) pg/mL (p < 0.001) at the end of HIIT. Hand grip strength did not change during course. By contrast, knee extensor strength significantly increased during HIIT [4.42 ± 1.43 → 5.28 ± 1.45 N/kg, p < 0.001], whereas the improvement of knee extensor strength was not significant from the start of exercise training to the start of HIIT. In addition, the change in knee extensor strength during HIIT was significantly associated with the hemoglobin A1c level at the start of exercise (R = - 0.55; p = 0.015). HIIT has a positive impact on skeletal muscle strength among in-hospital patients with advanced heart failure.

When phosphorylated at Thr148, the β2-subunit of AMP-activated kinase does not associate with glycogen in skeletal muscle.

PubMed

Xu, Hongyang; Frankenberg, Noni T; Lamb, Graham D; Gooley, Paul R; Stapleton, David I; Murphy, Robyn M

2016-07-01

The 5'-AMP-activated protein kinase (AMPK), a heterotrimeric complex that functions as an intracellular fuel sensor that affects metabolism, is activated in skeletal muscle in response to exercise and utilization of stored energy. The diffusibility properties of α- and β-AMPK were examined in isolated skeletal muscle fiber segments dissected from rat fast-twitch extensor digitorum longus and oxidative soleus muscles from which the surface membranes were removed by mechanical dissection. After the muscle segments were washed for 1 and 10 min, ∼60% and 75%, respectively, of the total AMPK pools were found in the diffusible fraction. After in vitro stimulation of the muscle, which resulted in an ∼80% decline in maximal force, 20% of the diffusible pool became bound in the fiber. This bound pool was not associated with glycogen, as determined by addition of a wash step containing amylase. Stimulation of extensor digitorum longus muscles resulted in 28% glycogen utilization and a 40% increase in phosphorylation of the downstream AMPK target acetyl carboxylase-CoA. This, however, had no effect on the proportion of total β2-AMPK that was phosphorylated in whole muscle homogenates measured by immunoprecipitation. These findings suggest that, in rat skeletal muscle, β2-AMPK is not associated with glycogen and that activation of AMPK by muscle contraction does not dephosphorylate β2-AMPK. These findings question the physiological relevance of the carbohydrate-binding function of β2-AMPK in skeletal muscle. Copyright © 2016 the American Physiological Society.

Elicitation and abrupt termination of behaviorally significant catchlike tension in a primitive insect.

PubMed

Hoyle, G; Field, L H

1983-07-01

Sustained steady contractural or catchlike tension (CT) occurs in the metathoracic extensor tibiae muscle of the primitive insect the weta (Orthoptera: Stenopelmatidae) during its characteristic leg-extension defense behavior or following leg-position conditioning. Similar action occurs occasionally in semi-intact preparations and is abruptly turned off by a single peripheral inhibitory impulse. These phenomena were reproduced routinely by first infusing saline containing 10(-8) M (or stronger) octopamine into the muscle for 12 min, and then stimulating the slow excitatory motor neuron SETi with a brief burst. Direct stimulation of the dorsal unpaired median neuron, innervating the extensor tibiae (DUMETi) prior to SETi stimulation, also led to CT. Both octopamine and DUMETi markedly enhanced the tension developed in response to a burst of impulses in SETi.

Functional anatomy of the gibbon forelimb: adaptations to a brachiating lifestyle

PubMed Central

Michilsens, Fana; Vereecke, Evie E; D'Août, Kristiaan; Aerts, Peter

2009-01-01

It has been shown that gibbons are able to brachiate with very low mechanical costs. The conversion of muscle activity into smooth, purposeful movement of the limb depends on the morphometry of muscles and their mechanical action on the skeleton. Despite the gibbon's reputation for excellence in brachiation, little information is available regarding either its gross musculoskeletal anatomy or its more detailed muscle–tendon architecture. We provide quantitative anatomical data on the muscle–tendon architecture (muscle mass, physiological cross-sectional area, fascicle length and tendon length) of the forelimb of four gibbon species, collected by detailed dissections of unfixed cadavers. Data are compared between different gibbon species and with similar published data of non-brachiating primates such as macaques, chimpanzees and humans. No quantitative differences are found between the studied gibbon species. Both their forelimb anatomy and muscle dimensions are comparable when normalized to the same body mass. Gibbons have shoulder flexors, extensors, rotator muscles and elbow flexors with a high power or work-generating capacity and their wrist flexors have a high force-generating capacity. Compared with other primates, the elbow flexors of gibbons are particularly powerful, suggesting that these muscles are particularly important for a brachiating lifestyle. Based on this anatomical study, the shoulder flexors, extensors, rotator muscles, elbow flexors and wrist flexors are expected to contribute the most to brachiation. PMID:19519640

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.

Skeletal muscle metabolism in hypokinetic rats

NASA Technical Reports Server (NTRS)

Tischler, M. E.

1984-01-01

Muscle growth, protein metabolism, and amino acid metabolism were studied in various groups of rats. Certain groups were adrenaliectomized; some rats were suspended while others (the controls) were weight bearing. Results show that: (1) metabolic changes in the extensor digitorum longus muscle of suspended rats are due primarily to increased circulating glucocorticoids; (2) metabolic changes in the soleus muscle due to higher steroid levels are probably potentiated by greater numbers of steroid receptors; and (3) not all metabolic responses of the soleus muscle to unloading are due to the elevated levels of glucocorticoids or the increased sensitivity of this muscle to these hormones.

Musculoskeletal modelling of an ostrich (Struthio camelus) pelvic limb: influence of limb orientation on muscular capacity during locomotion

PubMed Central

Rankin, Jeffery W.; Rubenson, Jonas; Rosenbluth, Kate H.; Siston, Robert A.; Delp, Scott L.

2015-01-01

We developed a three-dimensional, biomechanical computer model of the 36 major pelvic limb muscle groups in an ostrich (Struthio camelus) to investigate muscle function in this, the largest of extant birds and model organism for many studies of locomotor mechanics, body size, anatomy and evolution. Combined with experimental data, we use this model to test two main hypotheses. We first query whether ostriches use limb orientations (joint angles) that optimize the moment-generating capacities of their muscles during walking or running. Next, we test whether ostriches use limb orientations at mid-stance that keep their extensor muscles near maximal, and flexor muscles near minimal, moment arms. Our two hypotheses relate to the control priorities that a large bipedal animal might evolve under biomechanical constraints to achieve more effective static weight support. We find that ostriches do not use limb orientations to optimize the moment-generating capacities or moment arms of their muscles. We infer that dynamic properties of muscles or tendons might be better candidates for locomotor optimization. Regardless, general principles explaining why species choose particular joint orientations during locomotion are lacking, raising the question of whether such general principles exist or if clades evolve different patterns (e.g., weighting of muscle force–length or force–velocity properties in selecting postures). This leaves theoretical studies of muscle moment arms estimated for extinct animals at an impasse until studies of extant taxa answer these questions. Finally, we compare our model’s results against those of two prior studies of ostrich limb muscle moment arms, finding general agreement for many muscles. Some flexor and extensor muscles exhibit self-stabilization patterns (posture-dependent switches between flexor/extensor action) that ostriches may use to coordinate their locomotion. However, some conspicuous areas of disagreement in our results illustrate some cautionary principles. Importantly, tendon-travel empirical measurements of muscle moment arms must be carefully designed to preserve 3D muscle geometry lest their accuracy suffer relative to that of anatomically realistic models. The dearth of accurate experimental measurements of 3D moment arms of muscles in birds leaves uncertainty regarding the relative accuracy of different modelling or experimental datasets such as in ostriches. Our model, however, provides a comprehensive set of 3D estimates of muscle actions in ostriches for the first time, emphasizing that avian limb mechanics are highly three-dimensional and complex, and how no muscles act purely in the sagittal plane. A comparative synthesis of experiments and models such as ours could provide powerful synthesis into how anatomy, mechanics and control interact during locomotion and how these interactions evolve. Such a framework could remove obstacles impeding the analysis of muscle function in extinct taxa. PMID:26082859

Decreased specific force and power production of muscle fibers from myostatin-deficient mice are associated with a suppression of protein degradation.

PubMed

Mendias, Christopher L; Kayupov, Erdan; Bradley, Joshua R; Brooks, Susan V; Claflin, Dennis R

2011-07-01

Myostatin (MSTN) is a member of the transforming growth factor-β superfamily of cytokines and is a negative regulator of skeletal muscle mass. Compared with MSTN(+/+) mice, the extensor digitorum longus muscles of MSTN(-/-) mice exhibit hypertrophy, hyperplasia, and greater maximum isometric force production (F(o)), but decreased specific maximum isometric force (sF(o); F(o) normalized by muscle cross-sectional area). The reason for the reduction in sF(o) was not known. Studies in myotubes indicate that inhibiting myostatin may increase muscle mass by decreasing the expression of the E3 ubiquitin ligase atrogin-1, which could impact the force-generating capacity and size of muscle fibers. To gain a greater understanding of the influence of myostatin on muscle contractility, we determined the impact of myostatin deficiency on the contractility of permeabilized muscle fibers and on the levels of atrogin-1 and ubiquitinated myosin heavy chain in whole muscle. We hypothesized that single fibers from MSTN(-/-) mice have a greater F(o), but no difference in sF(o), and a decrease in atrogin-1 and ubiquitin-tagged myosin heavy chain levels. The results indicated that fibers from MSTN(-/-) mice have a greater cross-sectional area, but do not have a greater F(o) and have a sF(o) that is significantly lower than fibers from MSTN(+/+) mice. The extensor digitorum longus muscles from MSTN(-/-) mice also have reduced levels of atrogin-1 and ubiquitinated myosin heavy chain. These findings suggest that myostatin inhibition in otherwise healthy muscle increases the size of muscle fibers and decreases atrogin-1 levels, but does not increase the force production of individual muscle fibers.

ITKids part II: variation of postures and muscle activity in children using different information and communication technologies.

PubMed

Ciccarelli, Marina; Straker, Leon; Mathiassen, Svend Erik; Pollock, Clare

2011-01-01

There are concerns that insufficient variation in postural and muscle activity associated with use of modern information and communication technology (ICT) presents a risk for musculoskeletal ill-health among school children. However, scientific knowledge on physical exposure variation in this group is limited. The purpose of this study was to quantify postures and muscle activity of school children using different types of ICT. Postures of the head, upper back and upper arm, and muscle activity of the right and left upper trapezius and right forearm extensors were measured over 10-12 hours in nine school children using different types of ICT at school and away-from-school. Variation in postures and muscle activity was quantified using two indices, EVA{sd} and APDF₉₀-₁₀. Paper-based (Old) ICT tasks produced postures that were less neutral but more variable than electronics-based (New ICT) and Non-ICT tasks. Non-ICT tasks involved mean postures similar to New ICT tasks, but with greater variation. Variation of muscle activity was similar between ICT types in the right and left upper trapezius muscles. Non-ICT tasks produced more muscle activity variation in the right forearm extensor group compared to New and Old ICT tasks. Different ICT tasks produce different degrees of variation in posture and muscle activity. Combining tasks that use different ICT may increase overall exposure variation. More research is needed to determine what degree of postural and muscle activity variation is associated with reduced risk of musculoskeletal ill-health.

ACTN3 R577X Polymorphism and Neuromuscular Response to Resistance Training

PubMed Central

Gentil, Paulo; Pereira, Rinaldo W.; Leite, Tailce K.M.; Bottaro, Martim

2011-01-01

The R577X polymorphism at the ACTN3 gene has been associated with muscle strength, hypertrophy and athletic status. The X allele, which is associated with the absence of ACTN3 protein is supposed to impair performance of high force/velocity muscle contractions. The purpose of the present study was to investigate the association of the R577X polymorphism with the muscle response to resistance training in young men. One hundred forty one men performed two resistance training sessions per week for 11 weeks. Participants were tested for 1RM bench press, knee extensors peak torque, and knee extensors muscle thickness at baseline and after the training period. Genotyping was conducted using de DdeI restriction enzyme. Genotype distribution was 34.4% for RR, 47% for RX and 18.6% for the XX genotype. According to the results, the R577X polymorphism at the ACTN3 gene is not associated with baseline muscle strength or with the muscle strength response to resistance training. However, only carriers of the R allele showed increases in muscle thickness in response to training. Key points ACTN3 Genotype distribution in the present study was similar to others populations (34.4% for RR, 47% for RX, and 18.6% for the XX). The R577X polymorphism at the ACTN3 gene is not associated with baseline muscle strength or with the muscle strength response to resistance training. It appears that the R allele carriers respond better to muscle thickness gains in response to training. PMID:24149888

ACTN3 R577X Polymorphism and Neuromuscular Response to Resistance Training.

PubMed

Gentil, Paulo; Pereira, Rinaldo W; Leite, Tailce K M; Bottaro, Martim

2011-01-01

The R577X polymorphism at the ACTN3 gene has been associated with muscle strength, hypertrophy and athletic status. The X allele, which is associated with the absence of ACTN3 protein is supposed to impair performance of high force/velocity muscle contractions. The purpose of the present study was to investigate the association of the R577X polymorphism with the muscle response to resistance training in young men. One hundred forty one men performed two resistance training sessions per week for 11 weeks. Participants were tested for 1RM bench press, knee extensors peak torque, and knee extensors muscle thickness at baseline and after the training period. Genotyping was conducted using de DdeI restriction enzyme. Genotype distribution was 34.4% for RR, 47% for RX and 18.6% for the XX genotype. According to the results, the R577X polymorphism at the ACTN3 gene is not associated with baseline muscle strength or with the muscle strength response to resistance training. However, only carriers of the R allele showed increases in muscle thickness in response to training. Key pointsACTN3 Genotype distribution in the present study was similar to others populations (34.4% for RR, 47% for RX, and 18.6% for the XX).The R577X polymorphism at the ACTN3 gene is not associated with baseline muscle strength or with the muscle strength response to resistance training.It appears that the R allele carriers respond better to muscle thickness gains in response to training.

Therapeutic Plasma Exchange in a rare case myasthenic crisis after Botox injection.

PubMed

Chegini, Azita

2017-11-01

Botulinum toxin (Botox) injections are used as a cosmetic treatment to decrease wrinkles in face and chin. Being a neurotoxic agent it minimizes muscle activity, while side effects are usually rare. This article subsequently presents one case of these rare effects. A 30-year-old woman presenting with ptosis, diplopia, dysarthria, dysphagia and muscle weakness was admitted to our hospital. She had no history of disease. For cosmetic reasons, she had three Botox injections during the preceding months. On physical examination, muscle weakness 4/5 (cervical extensor, ocular and pharynx) was detected and a diagnosis of myasthenia gravis was made. Protective artificial ventilation was necessary. As a consequence, eight sessions of 2.5 L volume Therapeutic Plasma Exchange (TPE) were applied using normal saline/albumin as substitute. Due to TPE, her muscle force and clinical condition improved. Artificial ventilation could be stopped. Clinical symptoms of myasthenia gravis and systemic Botox effects are very similar. This should be taken into consideration during medical history taking. The injection of high doses of Botox (more than 200 units in every injection) or boostering within less than one month is dangerous. (Botox BCC2024). Systemic side effects can be treated using TPE to lower the circulating dose of Botox. Copyright © 2017 Elsevier B.V. All rights reserved.

Fiber transformation and replacement in low-frequency stimulated rabbit fast-twitch muscles.

PubMed

Schuler, M; Pette, D

1996-08-01

The fast-to-slow conversion of rabbit skeletal muscles by chronic low-frequency (10 Hz, 12 h daily) stimulation involves (1) sequential fast-to-slow fiber-type transitions in the order of type IID-->type IIA-->type I, and (2) the replacement of deteriorating fast-twitch glycolytic fibers by new fibers derived from satellite cells and myotubes. These two processes were analyzed in 30- and 60-day stimulated extensor digitorum longus and tibialis anterior muscles. Fast-to-slow transforming fibers were identified by myofibrillar actomyosin histochemistry as type C fibers and immunohistochemically by their reaction with monoclonal antibodies specific to slow and fast myosin heavy chain isoforms. In situ hybridization of mRNA specific to the myosin heavy chain I isoform identified all fibers expressing slow myosin, i.e., type I and C fibers. The fraction of transforming fibers ranged between 35% and 50% in 30-day stimulated muscles. The percentage of type I fibers (20%) was threefold elevated in extensor digitorum longus muscle, but unaltered (3.5%) in tibialis anterior muscle, suggesting that fast-to-slow fiber conversion was more advanced in the former than in the latter. Fiber replacement was indicated by the finding that the fiber populations of both muscles contained 15% myotubes or small fibers with central nuclei. In situ hybridization revealed that myotubes and small regenerating fibers uniformly expressed myosin heavy chain I mRNA. Similarly, high percentages of slow-myosin-expressing myotubes and small fibers were found in 60-day stimulated muscles.

Muscle coordination in cycling: effect of surface incline and posture.

PubMed

Li, L; Caldwell, G E

1998-09-01

The purpose of the present study was to examine the neuromuscular modifications of cyclists to changes in grade and posture. Eight subjects were tested on a computerized ergometer under three conditions with the same work rate (250 W): pedaling on the level while seated, 8% uphill while seated, and 8% uphill while standing (ST). High-speed video was taken in conjunction with surface electromyography (EMG) of six lower extremity muscles. Results showed that rectus femoris, gluteus maximus (GM), and tibialis anterior had greater EMG magnitude in the ST condition. GM, rectus femoris, and the vastus lateralis demonstrated activity over a greater portion of the crank cycle in the ST condition. The muscle activities of gastrocnemius and biceps femoris did not exhibit profound differences among conditions. Overall, the change of cycling grade alone from 0 to 8% did not induce a significant change in neuromuscular coordination. However, the postural change from seated to ST pedaling at 8% uphill grade was accompanied by increased and/or prolonged muscle activity of hip and knee extensors. The observed EMG activity patterns were discussed with respect to lower extremity joint moments. Monoarticular extensor muscles (GM, vastus lateralis) demonstrated greater modifications in activity patterns with the change in posture compared with their biarticular counterparts. Furthermore, muscle coordination among antagonist pairs of mono- and biarticular muscles was altered in the ST condition; this finding provides support for the notion that muscles within these antagonist pairs have different functions.

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.

Ischemic conditioning increases strength and volitional activation of paretic muscle in chronic stroke: a pilot study.

PubMed

Hyngstrom, Allison S; Murphy, Spencer A; Nguyen, Jennifer; Schmit, Brian D; Negro, Francesco; Gutterman, David D; Durand, Matthew J

2018-05-01

Ischemic conditioning (IC) on the arm or leg has emerged as an intervention to improve strength and performance in healthy populations, but the effects on neurological populations are unknown. The purpose of this study was to quantify the effects of a single session of IC on knee extensor strength and muscle activation in chronic stroke survivors. Maximal knee extensor torque measurements and surface EMG were quantified in 10 chronic stroke survivors (>1 yr poststroke) with hemiparesis before and after a single session of IC or sham on the paretic leg. IC consisted of 5 min of compression with a proximal thigh cuff (inflation pressure = 225 mmHg for IC or 25 mmHg for sham) followed by 5 min of rest. This was repeated five times. Maximal knee extensor strength, EMG magnitude, and motor unit firing behavior were measured before and immediately after IC or sham. IC increased paretic leg strength by 10.6 ± 8.5 Nm, whereas no difference was observed in the sham group (change in sham = 1.3 ± 2.9 Nm, P = 0.001 IC vs. sham). IC-induced increases in strength were accompanied by a 31 ± 15% increase in the magnitude of muscle EMG during maximal contractions and a 5% decrease in motor unit recruitment thresholds during submaximal contractions. Individuals who had the most asymmetry in strength between their paretic and nonparetic legs had the largest increases in strength ( r 2  = 0.54). This study provides evidence that a single session of IC can increase strength through improved muscle activation in chronic stroke survivors. NEW & NOTEWORTHY Present rehabilitation strategies for chronic stroke survivors do not optimally activate paretic muscle, and this limits potential strength gains. Ischemic conditioning of a limb has emerged as an effective strategy to improve muscle performance in healthy individuals but has never been tested in neurological populations. In this study, we show that ischemic conditioning on the paretic leg of chronic stroke survivors can increase leg strength and muscle activation while reducing motor unit recruitment thresholds.

Evidence for repetitive load in the trapezius muscle during a tapping task.

PubMed

Tomatis, L; Müller, C; Nakaseko, M; Läubli, T

2012-08-01

Many studies describe the trapezius muscle activation pattern during repetitive key-tapping focusing on continuous activation. The objectives of this study were to determine whether the upper trapezius is phasically active during supported key tapping, whether this activity is cross-correlated with forearm muscle activity, and whether trapezius activity depends on key characteristic. Thirteen subjects (29.7 ± 11.4 years) were tested. Surface EMG of the finger's extensor and flexor and of the trapezius muscles, as well as the key on-off signal was recorded while the subject performed a 2-min session of key tapping at 4 Hz. The linear envelopes obtained were cut into single tapping cycles extending from one onset to the next onset signal and subsequently time-normalized. Effect size between mean range and maximal standard deviation was calculated to determine as to whether a burst of trapezius muscle activation was present. Cross-correlation was used to determine the time-lag of the activity bursts between forearm and trapezius muscles. For each person the mean and standard deviation of the cross-correlations coefficient between forearm muscles and trapezius were determined. Results showed a burst of activation in the trapezius muscle during most of the tapping cycles. The calculated effect size was ≥0.5 in 67% of the cases. Cross-correlation factors between forearm and trapezius muscle activity were between 0.75 and 0.98 for both extensor and flexor muscles. The cross-correlated phasic trapezius activity did not depend on key characteristics. Trapezius muscle was dynamically active during key tapping; its activity was clearly correlated with forearm muscles' activity.

Functional anatomy of the lateral collateral ligament of the elbow.

PubMed

Hackl, M; Bercher, M; Wegmann, K; Müller, L P; Dargel, J

2016-07-01

The aim of this study was to analyze the functional anatomy of the lateral collateral ligament complex (LCLC) and the surrounding forearm extensors. Using 81 human cadaveric upper extremities, the anatomy of the forearm extensors-especially the anconeus, supinator and extensor carpi ulnaris (ECU)-was analyzed. After removal of aforementioned extensors the functional anatomy of the LCLC was analyzed. The origin of the LCLC was evaluated for isometry. The insertion types of the lateral ulnar collateral ligament (LUCL) were analyzed and classified. The ECU runs parallel to the RCL to dynamically preserve varus stability. The supinator and anconeus muscle fibers coalesce with the LCLC and lengthen during pronation. The anconeus fibers run parallel to the LUCL in full flexion. The LCLC consists of the annular ligament (AL) and the isometric radial collateral ligament (RCL). During elbow flexion, its posterior branches (LUCL) tighten while the anterior branches loosen. When performing a pivot shift test, the loosened LUCL fibers do not fully tighten in full extension. The LUCL inserts along with the AL at the supinator crest. Three different insertion types could be observed. The LUCL represents the posterior branch of the RCL rather than a distinct ligament. It is non-isometric and lengthens during elbow flexion. The RCL was found to be of vital importance for neutralization of posterolateral rotatory forces. Pronation of the forearm actively stabilizes the elbow joint as the supinator, anconeus and biceps muscle work in unison to increase posterolateral rotatory stability.

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.

Comparison of the effect of selected muscle groups fatigue on postural control during bipedal stance in healthy young women.

PubMed

Shirazi, Zahra Rojhani; Jahromi, Fatemeh Nikhalat

2013-09-01

The maintenance of balance is an essential requirement for the performance of daily tasks and sporting activities and muscular fatigue is a factor to impair postural control, so this study was done to compare the effect of selected muscle groups fatigue on postural control during bipedal stance in healthy subjects. Fifteen healthy female students (24.3 ± 2.6 years) completed three testing session with a break period of at least 2 days. During each session, postural control was assessed during two 30-s trials of bipedal stance with eyes close before and after the fatigue protocol. Fatigue protocols were performed by 60% of their unfatigued Maximum Voluntary Contraction of unilateral ankle plantar flexors, bilateral lumbar extensors and bilateral neck extensors. One of the three fatigue protocols was performed on each session. The result showed that fatigue had a significant effect on COP velocity and it increase COP velocity but there was not found any difference in postural sway between muscle groups. Localized muscle fatigue caused deficits in postural control regardless of the location of fatigue. Authors suggest the possibility of the contributions of central mechanisms to postural deficits due to fatigue and it seems that difference was not between muscle groups due to central fatigue.

Short physical performance battery for middle-aged and older adult cardiovascular disease patients: implication for strength tests and lower extremity morphological evaluation.

PubMed

Yasuda, Tomohiro; Fukumura, Kazuya; Nakajima, Toshiaki

2017-04-01

[Purpose] To examine if the SPPB is higher with healthy subjects than outpatients, which was higher than inpatients and if the SPPB can be validated assessment tool for strength tests and lower extremity morphological evaluation in cardiovascular disease patients. [Subjects and Methods] Twenty-four middle aged and older adults with cardiovascular disease were recruited from inpatient and outpatient facilities and assigned to separate experimental groups. Twelve age-matched healthy volunteers were assigned to a control group. SPPB test was used to assess balance and functional motilities. The test outcomes were compared with level of care (inpatient vs. outpatient), physical characteristics, strength and lower extremity morphology. [Results] Total SPPB scores, strength tests (knee extensor muscle strength), and lower extremity morphological evaluation (muscle thickness of anterior and posterior mid-thigh and posterior lower-leg) were greater in healthy subjects and outpatients groups compared with inpatients. To predict total Short Physical Performance Battery scores, the predicted knee extension and anterior mid-thigh muscle thickness were calculated. [Conclusion] The SPPB is an effective tool as the strength tests and lower extremity morphological evaluation for middle-aged and older adult cardiovascular disease patients. Notably, high knee extensor muscle strength and quadriceps femoris muscle thickness are positively associated with high SPPB scores.

RSI: oxygen consumption, blood flow, and reoxygenation in patients suffering RSI measured by noninvasive optical spectroscopy

NASA Astrophysics Data System (ADS)

Thijssen, Dick H. J.; van Uden, Caro J. T.; Krijgsman, Hans; Colier, Willy N. J. M.

2003-07-01

Background: Repetitive Strain Injury (RSI) is a major problem in nowadays health care and creates high financial costs and personal distress. Average prevalence rates in the Netherlands vary from 20-40% of the working population. Insight into the patho-physiological mechanism of RSI is important in order to establish adequate treatment and prevention programs. Objective: The aim of this study was to gain insight in muscle oxygen consumption (mVO2), blood flow (BF), and reoxygenation (ReOx) in the forearm of computer workers with stage III Repetitive Strain Injury (RSI). Method: We have used continuous wave infrared spectroscopy (NIRS) to measure these variables. Measurements were conducted on the extensor and flexor muscle in both arms as well in RSI-patients (n=10) as in control subjects (n=21). A protocol of increased isometric repetitive contraction in a handgrip ergonometer was used with increasing levels of strength. Results: mVO2 in the extensor muscle in RSI-subjects (dominant side) was increased compared to control subjects and compared to the non-dominant side (p<0.05). ReOx was not increased in RSI (dominant side-extensor muscle). However, there was a tendency towards statistical significance (p=0.065). BF in rest was equal in both groups, however after exercise it tended to be increased. Half-time recovery (T ») was measured during only one part of the protocol and it was significantly increased (p<0.05). Conclusion: mVO2 in RSI is impaired. BF and ReOx did not show difference between both groups. Future research should aim at a microvascular dysfunction in RSI.

A modified surgical technique for neglected fracture of lateral humeral condyle in children.

PubMed

Sulaiman, Abdul Razak; Munajat, Ismail; Mohd, Emil Fazliq

2011-11-01

Operative treatment for neglected fracture of lateral humeral condyle (LHC) is difficult because of contracted muscle, fibrous tissue formation, and indistinct bony edges. Its success depends on the ability to preserve blood supply during the surgery. We retrospectively reviewed eight cases of neglected fracture of LHC in children treated with open reduction with selected multiple 'V' lengthening of common extensor muscle and internal fixation. The patients were between 3 and 8 years of age. The period of neglect was between 3 and 20 weeks. Four patients with displacement of more than 10 mm and neglect for 5 weeks or more required lengthening of common extensor muscle aponeurosis. The follow-up assessments were between 1 and 6.3 years with a mean of 4.4 years. All patients had union by 2 months. They gained improvement of flexion range of motion between 60° and 120° with a mean of 86.3°. Loss of final range of motion compared with the normal side was between 5° and 35° with a mean of 10°. No patient had limitation of activities or pain. Six cases had excellent and two cases had good Dillon functional score. All patients had lateral condyle prominent with different severities. There was one mild avascular necrosis and one fishtail deformity. Both of them had almost full range of motion. All patients had early physeal closure, except one, who had only 1 year follow-up. There was no case of progressive valgus deformity. Children with neglected fracture of LHC would benefit from anatomical reduction and internal fixation through a proper exposure and if indicated combined with multiple 'V' lengthening of common extensor muscle aponeurosis. This is a level IV study.

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

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.

Degeneration and regeneration of neuromuscular junction architecture in rat skeletal muscle fibers damaged by bupivacaine hydrochloride.

PubMed

Nishizawa, Tomie; Tamaki, Hiroyuki; Kasuga, Norikatsu; Takekura, Hiroaki

2003-01-01

We evaluated the degeneration and regeneration of neuromuscular junctions (NMJs) on the extensor digitorum longus muscle of Fischer 344 rats between 4 h and 3 weeks after bupivacaine hydrochloride (BPVC) injection, which induces muscle fiber necrosis, using histochemical staining by acetylcholine esterase (AchE)-silver and electron microscopy. Degeneration of muscle fibers and NMJs was observed 4 h after BPVC injection. One week after BPVC injection, some terminal axons were almost completely retracted, and the level of basal lamina-associated AchE in some NMJ regions had gradually disappeared. At that time, the depression contained a few, mostly pit-like or elongated oval invaginations: the incipient junctional folds and some NMJs did not have any secondary junctional fold. By 2 weeks after the BPVC injection, secondary junctional folds began to develop: however, the number of secondary junctional folds was clearly less than that in normal NMJs. At 3 weeks when regeneration of muscle fibers was well advanced, the staining for AchE at the end-plates became stronger and better-defined. The volume density of mitochondria in the terminal area of the terminal significantly decreased upon BPVC-induced destruction of the NMJ, and the density reached the lowest value 24 h after BPVC injection. Significant changes in the ultrastructural features of the architecture of NMJs occurred in skeletal muscle fibers damaged by BPVC during both the degeneration and regeneration processes. The changes in the ultrastructural and morphological features of the NMJ architecture during the regeneration of degenerated muscle fibers resembled those that occur during the differentiation of normal muscle fibers.

Bilateral anterior tarsal tunnel syndrome variant secondary to extensor hallucis brevis muscle hypertrophy in a ballet dancer: a case report.

PubMed

Tennant, Joshua N; Rungprai, Chamnanni; Phisitkul, Phinit

2014-12-01

We present a case of bilateral anterior tarsal tunnel syndrome secondary EHB hypertrophy in a dancer, with successful treatment with bilateral EHB muscle excisions for decompression. The bilateral presentation of this case with the treatment of EHB muscle excision is the first of its type reported in the literature. Copyright © 2014 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

Sex Differences in Neuromuscular Fatigability of the Knee Extensors Post-Stroke

PubMed Central

Kirking, Meghan; Berrios Barillas, Reivian; Nelson, Philip Andrew; Hunter, Sandra Kay; Hyngstrom, Allison

2017-01-01

Background and Purpose: Despite the implications of optimizing strength training post-stroke, little is known about the differences in fatigability between men and women with chronic stroke. The purpose of this study was to determine the sex differences in knee extensor muscle fatigability and potential mechanisms in individuals with stroke. Methods: Eighteen participants (10 men, eight women) with chronic stroke (≥6 months) and 23 (12 men, 11 women) nonstroke controls participated in the study. Participants performed an intermittent isometric contraction task (6 s contraction, 3 s rest) at 30% of maximal voluntary contraction (MVC) torque until failure to maintain the target torque. Electromyography was used to determine muscle activation and contractile properties were assessed with electrical stimulation of the quadriceps muscles. Results: Individuals with stroke had a briefer task duration (greater fatigability) than nonstroke individuals (24.1 ± 17 min vs. 34.9 ± 16 min). Men were more fatigable than women for both nonstroke controls and individuals with stroke (17.9 ± 9 min vs. 41.6 ± 15 min). Individuals with stroke had less fatigue-related changes in muscle contractile properties and women with stroke differed in their muscle activation strategy during the fatiguing contractions. Conclusions: Men and women fatigue differently post-stroke and this may be due to the way they neurally activate muscle groups. PMID:28085089

Functional and morphological adaptations to aging in knee extensor muscles of physically active men.

PubMed

Baroni, Bruno Manfredini; Geremia, Jeam Marcel; Rodrigues, Rodrigo; Borges, Marcelo Krás; Jinha, Azim; Herzog, Walter; Vaz, Marco Aurélio

2013-10-01

It is not known if a physically active lifestyle, without systematic training, is sufficient to combat age-related muscle and strength loss. Therefore, the purpose of this study was to evaluate if the maintenance of a physically active lifestyle prevents muscle impairments due to aging. To address this issue, we evaluated 33 healthy men with similar physical activity levels (IPAQ = 2) across a large range of ages. Functional (torque-angle and torque-velocity relations) and morphological (vastus lateralis muscle architecture) properties of the knee extensor muscles were assessed and compared between three age groups: young adults (30 ± 6 y), middle-aged subjects (50 ± 7 y) and elderly subjects (69 ± 5 y). Isometric peak torques were significantly lower (30% to 36%) in elderly group subjects compared with the young adults. Concentric peak torques were significantly lower in the middle aged (18% to 32%) and elderly group (40% to 53%) compared with the young adults. Vastus lateralis thickness and fascicles lengths were significantly smaller in the elderly group subjects (15.8 ± 3.9 mm; 99.1 ± 25.8 mm) compared with the young adults (19.8 ± 3.6 mm; 152.1 ± 42.0 mm). These findings suggest that a physically active lifestyle, without systematic training, is not sufficient to avoid loss of strength and muscle mass with aging.

Effect of muscle relaxation in the foot on simultaneous muscle contraction in the contralateral hand.

PubMed

Kato, Kouki; Kanosue, Kazuyuki

2016-10-28

We investigated the effects of foot muscle relaxation and contraction on muscle activities in the hand on both ipsilateral and contralateral sides. The subjects sat in an armchair with hands in the pronated position. They were able to freely move their right/left hand and foot. They performed three tasks for both ipsilateral (right hand and right foot) and contralateral limb coordination (left hand and right foot for a total of six tasks). These tasks involved: (1) wrist extension from a flexed (resting) position, (2) wrist extension with simultaneous ankle dorsiflexion from a plantarflexed (resting) position, and (3) wrist extension with simultaneous ankle relaxation from a dorsiflexed position. The subjects performed each task as fast as possible after hearing the start signal. Reaction time for the wrist extensor contraction (i.e. the degree to which it preceded the motor reaction time), as observed in electromyography (EMG), became longer when it was concurrently done with relaxation of the ankle dorsiflexor. Also, the magnitude of EMG activity became smaller, as compared with activity when wrist extensor contraction was done alone or with contraction of the ankle dorsiflexor. These effects were observed not only for the ipsilateral hand, but also for the contralateral hand. Our findings suggest that muscle relaxation in one limb interferes with muscle contraction in both the ipsilateral and contralateral limbs. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Alterations of the In Vivo Torque-Velocity Relationship of Human Skeletal Muscle Following 30 Days Exposure to Simulated Microgravity

NASA Technical Reports Server (NTRS)

Dudley, Gary A.; Duvoisin, Marc R.; Convertino, Victor A.; Buchanan, Paul

1989-01-01

The purpose of this study was to examine the effect of 30 d of 6 deg headdown bedrest (BR) on the in vivo strength of skeletal muscle. Peak angle specific (0.78 rad below horizontal) torque of the knee extensor (KE) and flexor (KF) muscle groups of both limbs was assessed during unilateral efforts at four speeds (0.52, 1.74, 2.97 and 4.19 rad/s) during concentric and at three speeds (0.52, 1.74 and 2.97 rad/s) during eccentric actions. The average decrease (P less than 0.05) of peak angle specific torque directly post-BR for the KE across speeds of concentric and eccentric actions was about 19% (n = 7). Recovery for 30 d following BR markedly improved strength to about 92% (P greater than 0.05) of 'normal'. Strength of the KF was not altered (P greater than 0.05) by BR (about a 6% decrease independent of speed and type of muscle action). Changes of strength were not affected by the type or speed of muscle action. The results indicate that strength of ex-tensor more than of flexor muscle groups of the lower limb is decreased by 30 d of bedrest and that this response does not alter the nature of the in vivo torque-velocity relation.

The Hindlimb Myology of Tyto alba (Tytonidae, Strigiformes, Aves).

PubMed

Mosto, M C

2017-02-01

This work is the first myological dissection performed in detail on the hindlimb of Tyto alba. Six specimens were dissected and their muscle masses were obtained. T. alba has the classical myological pattern present in other species of Strigiformes, such as a well-developed m. flexor digitorum longus and the absence of the m. plantaris, flexor cruris lateralis and ambiens. Also, T. alba lacks the m. extensor propius digiti III, m. extensor propius digiti IV and m. lumbricalis, present in the Strigidae. Hindlimb muscle mass accounts for 14.13% of total body mass, which is within the range of values of both nocturnal (Strigiformes) and diurnal (Falconidae and Accipitridae) raptors. This study provides important information for future studies related to functional morphology and ecomorphology. © 2016 Blackwell Verlag GmbH.

Control of trunk motion following sudden stop perturbations during cart pushing.

PubMed

Lee, Yun-Ju; Hoozemans, Marco J M; van Dieën, Jaap H

2011-01-04

External perturbations during pushing tasks have been suggested to be a risk factor for low-back symptoms. An experiment was designed to investigate whether self-induced and externally induced sudden stops while pushing a high inertia cart influence trunk motions, and how flexor and extensor muscles counteract these perturbations. Twelve healthy male participants pushed a 200 kg cart at shoulder height and hip height. Pushing while walking was compared to situations in which participants had to stop the cart suddenly (self-induced stop) or in which the wheels of the cart were unexpectedly blocked (externally induced stop). For the perturbed conditions, the peak values and the maximum changes from the reference condition (pushing while walking) of the external moment at L5/S1, trunk inclination and electromyographic amplitudes of trunk muscles were determined. In the self-induced stop, a voluntary trunk extension occurred. Initial responses in both stops consisted of flexor and extensor muscle cocontraction. In self-induced stops this was followed by sustained extensor activity. In the externally induced stops, an external extension moment caused a decrease in trunk inclination. The opposite directions of the internal moment and trunk motion in the externally induced stop while pushing at shoulder height may indicate insufficient active control of trunk posture. Consequently, sudden blocking of the wheels in pushing at shoulder height may put the low back at risk of mechanical injury. Copyright © 2010 Elsevier Ltd. All rights reserved.

BIOMECHANICAL DIFFERENCES IN BRAZILIAN JIU-JITSU ATHLETES: THE ROLE OF COMBAT STYLE.

PubMed

Lima, Pedro Olavo de Paula; Lima, Alane Almeida; Coelho, Anita Camila Sampaio; Lima, Yuri Lopes; Almeida, Gabriel Peixoto Leão; Bezerra, Márcio Almeida; de Oliveira, Rodrigo Ribeiro

2017-02-01

Brazilian Jiu-Jitsu (BJJ) athletes can be divided into two combat styles: pass fighters (PFs) and guard fighters (GFs). Flexibility of the posterior chain muscles is highly necessary in these athletes, especially in GFs. On the other hand, isometric strength of the trunk extensors is required in PFs. Handgrip strength is important in holding the kimono of the opponent, and symmetrical lower-limb strength is important for the prevention of injuries due to the overload caused by training. The aim of this study was to compare the biomechanical profiles of BJJ athletes with different combat styles using the following outcome measures: flexibility, trunk extensor isometric endurance, postural balance, handgrip isometric endurance and lower-limb muscle strength. A cross-sectional study was conducted using 19 GFs and 19 PFs. The sit-and-reach test was used to evaluate the flexibility of the posterior chain muscles. The Biodex Balance System® was used to evaluate balance. A handgrip dynamometer and a dorsal dynamometer were used to evaluate handgrip and trunk extensor endurance, respectively. Quadriceps and hamstring strength were evaluated with an isokinetic dynamometer at 60 °/s. No differences were observed between groups in terms of flexibility, balance, handgrip isometric endurance or quadriceps and hamstring strength; however, PFs (81.33) showed more isometric trunk extension endurance than GFs (68.85) ( p = 0.02). Both groups had low values for hamstring/quadriceps ratio. No significant biomechanical differences were observed between PFs and GFs. 2b.

Changes of Excitability in M1 Induced by Neuromuscular Electrical Stimulation Differ Between Presence and Absence of Voluntary Drive

ERIC Educational Resources Information Center

Sugawara, Kenichi; Tanabe, Shigeo; Higashi, Toshio; Tsurumi, Takamasa; Kasai, Tatsuya

2011-01-01

The aim of this study is to investigate excitability changes in the human motor cortex induced by variable therapeutic electrical stimulations (TESs) with or without voluntary drive. We recorded motor-evoked potentials (MEPs) from extensor and flexor carpi radialis (FCR) muscles at rest and during FCR muscle contraction after the application of…

Fibularis tertius: revisiting the anatomy.

PubMed

Rourke, K; Dafydd, H; Parkin, I G

2007-11-01

Fibularis tertius (FT) may be used during reconstructive surgery and muscle transposition with retention of function. The muscle was examined in both lower limbs of 41 cadavers. Measurements were made of muscle belly length and width, tendon length and width, and the size of the origin on the fibula. Tendon insertion, nerve and blood supplies were also examined. FT was absent in five (6.1%) lower limbs of three (7.3%) subjects. The size of its origin demonstrated inter- and intra-individual variation. FT arose from the distal fibula and on average occupied (28.4 +/- 9.1)% (mean +/- S. D.) of the total shaft length. In all cases the tendon inserted into the dorsal surface of the shafts of both the fourth and fifth metatarsals. A small nerve branch consistently arose from the deep fibular nerve near the origin of extensor digitorum longus. The nerve ran parallel to the length of this muscle, between it and extensor hallucis longus, before piercing FT. Anatomy textbooks describe FT as inserting into the fifth metatarsal only. This study, supported by data from previous reports, suggests that the "textbook" accounts of FT should be updated to record that most commonly its tendon reaches both the fourth and fifth metatarsals.

Whey protein with potassium bicarbonate supplement attenuates the reduction in muscle oxidative capacity during 19 days of bed rest.

PubMed

Bosutti, Alessandra; Salanova, Michele; Blottner, Dieter; Buehlmeier, Judith; Mulder, Edwin; Rittweger, Jörn; Yap, Moi Hoon; Ganse, Bergita; Degens, Hans

2016-10-01

The effectiveness of whey protein plus potassium bicarbonate-enriched diet (WP+KHCO 3 ) in mitigating disuse-induced changes in muscle fiber oxidative capacity and capillarization was investigated in a 21-day crossover design bed rest study. Ten healthy men (31 ± 6 yr) once received WP+KHCO 3 and once received a standardized isocaloric diet. Muscle biopsies were taken 2 days before and during the 19th day of bed rest (BR) from the soleus (SOL) and vastus lateralis (VL) muscle. Whole-body aerobic power (V̇o 2 max ), muscle fatigue, and isometric strength of knee extensor and plantar flexor muscles were monitored. Muscle fiber types and capillaries were identified by immunohistochemistry. Fiber oxidative capacity was determined as the optical density (OD) at 660 nm of succinate dehydrogenase (SDH)-stained sections. The product of fiber cross-sectional area and SDH-OD (integrated SDH) indicated the maximal oxygen consumption of that fiber. The maximal oxygen consumption supported by a capillary was calculated as the integrated SDH in its supply area. BR reduced isometric strength of knee extensor muscles (P < 0.05), and the fiber oxidative capacity (P < 0.001) and V̇o 2 max (P = 0.042), but had no significant impact on muscle capillarization or fatigue resistance of thigh muscles. The maximal oxygen consumption supported by a capillary was reduced by 24% in SOL and 16% in VL (P < 0.001). WP+KHCO 3 attenuated the disuse-induced reduction in fiber oxidative capacity in both muscles (P < 0.01). In conclusion, following 19 days of bed rest, the decrement in fiber oxidative capacity is proportionally larger than the loss of capillaries. WP+KHCO 3 appears to attenuate disuse-induced reductions in fiber oxidative capacity. Copyright © 2016 the American Physiological Society.

Hip rate of force development and strength are impaired in females with patellofemoral pain without signs of altered gluteus medius and maximus morphology.

PubMed

Nunes, Guilherme S; Barton, Christian John; Serrão, Fábio Viadanna

2018-02-01

To compare rate of force development (RFD) and isometric muscle strength of the hip abductors and extensors; and the thickness and the amount of non-contractile tissue of the gluteus medius and maximus between females with and without patellofemoral pain (PFP). Cross-sectional study. Fifty-four physically active females (27 with PFP and 27 healthy individuals) were studied. Hip muscle isometric strength and RFD was evaluated using isokinetic dynamometry. RFD was measured until 30%, 60%, and 90% of the maximal isometric torque (MIT). Hip muscle morphology was evaluated using ultrasonography. The PFP group possessed slower RFD compared to the control group by 33% for hip abductors until 90%MIT (-0.23%/ms, 95%CI -0.44 to -0.02, ES=0.59); by 51% for hip extensors until 30%MIT (-0.42%/ms, 95%CI -0.66 to -0.18, ES=0.97); and by 55% for hip extensors until 60%MIT (-0.36%/ms, 95%CI -0.60 to -0.12, ES=0.81). The PFP group possessed reduced isometric torque compared to the control group by 10% for hip abduction (-16.0Nm/kg×100, 95% CI -30.2 to -1.9, ES=0.61) and by 15% for hip extension (-30.1Nm/kg×100, 95%CI -51.4 to -8.9, ES=0.76). No significant between group differences for the thickness and the amount of non-contractile tissue of the gluteus medius and maximus were identified. Females with PFP have deficits in isometric strength and RFD in hip abduction and extension. RFD deficits are greater than strength deficits which may highlight their potential importance. Hip muscle strength and RFD deficits do not appear to be explained by muscle thickness or proportion of non-contractile tissue of the gluteal musculature as measured by ultrasound. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

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.

Age-Related Differences in Maximal and Rapid Torque Characteristics of the Hip Extensors and Dynamic Postural Balance in Healthy, Young and Old Females.

PubMed

Palmer, Ty B; Thiele, Ryan M; Thompson, Brennan J

2017-02-01

Palmer, TB, Thiele, RM, and Thompson, BJ. Age-related differences in maximal and rapid torque characteristics of the hip extensors and dynamic postural balance in healthy, young and old females. J Strength Cond Res 31(2): 480-488, 2017-The purpose of this study was to examine age-related differences in maximal and rapid torque characteristics of the hip extensor muscles and dynamic postural balance in healthy, young and older females. Eleven younger (age, 26 ± 8 years) and 11 older (age, 67 ± 8 years) females performed 2 isometric maximal voluntary contractions (MVCs) of the hip extensor muscles. Absolute and relative peak torque (PT) and rate of torque development (RTD) at early (0-50 ms) and late (0-200 ms) phases of muscle contraction were examined during each MVC. Dynamic postural balance was assessed using a commercially designed balance testing device, which provides a measurement of dynamic stability based on the overall stability index (OSI). Results indicated that absolute PT and early (RTD50) and late (RTD200) RTD variables were lower (p = 0.009-0.050), and postural OSI was higher (p = 0.011) in the old compared with the younger females; however, no differences were observed for relative PT or RTD variables (p = 0.113-0.895). A significant relationship was also observed in the older (r = -0.601; p = 0.050) but not the younger (r = -0.132; p = 0.698) females between RTD50 and OSI. The lower absolute PT and RTD and higher OSI values for the old females may contribute to the increased functional limitations often observed in older adults. The significant relationship observed in the older females between OSI and RTD50 perhaps suggests that these age-related declines in explosive strength may be an important characteristic relevant to dynamic balance scores, especially in older populations.

V1 and v2b interneurons secure the alternating flexor-extensor motor activity mice require for limbed locomotion.

PubMed

Zhang, Jingming; Lanuza, Guillermo M; Britz, Olivier; Wang, Zhi; Siembab, Valerie C; Zhang, Ying; Velasquez, Tomoko; Alvarez, Francisco J; Frank, Eric; Goulding, Martyn

2014-04-02

Reciprocal activation of flexor and extensor muscles constitutes the fundamental mechanism that tetrapod vertebrates use for locomotion and limb-driven reflex behaviors. This aspect of motor coordination is controlled by inhibitory neurons in the spinal cord; however, the identity of the spinal interneurons that serve this function is not known. Here, we show that the production of an alternating flexor-extensor motor rhythm depends on the composite activities of two classes of ventrally located inhibitory neurons, V1 and V2b interneurons (INs). Abrogating V1 and V2b IN-derived neurotransmission in the isolated spinal cord results in a synchronous pattern of L2 flexor-related and L5 extensor-related locomotor activity. Mice lacking V1 and V2b inhibition are unable to articulate their limb joints and display marked deficits in limb-driven reflex movements. Taken together, these findings identify V1- and V2b-derived neurons as the core interneuronal components of the limb central pattern generator (CPG) that coordinate flexor-extensor motor activity. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of resistance exercise training combined with relatively low vascular occlusion.

PubMed

Sumide, Takahiro; Sakuraba, Keishoku; Sawaki, Keisuke; Ohmura, Hirotoshi; Tamura, Yoshifumi

2009-01-01

Previous studies have demonstrated that a low-intensity resistance exercise, combined with vascular occlusion, results in a marked increase in muscular size and strength. We investigated the optimal pressure for reduction of muscle blood flow with resistance exercise to increase the muscular strength and endurance. Twenty-one subjects were randomly divided into four groups by the different application of vascular occlusion pressure at the proximal of thigh: without any pressure (0-pressure group), with a pressure of 50mmHg (50-pressure group), with a pressure of 150mmHg (150-pressure group), and with a pressure of 250mmHg (250-pressure group). The isokinetic muscle strength at angular velocities of 60 and 180 degrees /s, total muscle work, and the cross-sectional knee extensor muscle area were assessed before and after exercise. Exercise was performed three times a week over an 8-week period at an intensity of approximately 20% of one-repetition maximum for straight leg raising and hip joint adduction and maximum force for abduction training. A significant increase in strength at 180 degrees /s was noted after exercise in all subjects who exercised under vascular occlusion. Total muscle work increased significantly in the 50- and 150-pressure groups (P<0.05, P<0.01, respectively). There was no significant increase in cross-sectional knee extensor muscle area in any groups. In conclusion, resistance exercise with relatively low vascular occlusion pressure is potentially useful to increase muscle strength and endurance without discomfort.

Muscle oxygenation of vastus lateralis and medialis muscles during alternating and pulsed current electrical stimulation.

PubMed

Aldayel, Abdulaziz; Muthalib, Makii; Jubeau, Marc; McGuigan, Michael; Nosaka, Kazunori

2011-05-01

This study compared between alternating and pulsed current electrical muscle stimulation (EMS) for muscle oxygenation and blood volume during isometric contractions. Nine healthy men (23-48 years) received alternating current EMS (2500 Hz) modulated at 75 Hz on the knee extensors of one leg, and pulsed current EMS (75 Hz) for the other leg separated by 2 weeks in a randomised, counter-balanced order. Pulse duration (400 μs), on-off ratio (5-15 s) and other stimulation parameters were matched between conditions and 30 isometric contractions were induced at the knee joint angle of 100° (0° full extension). Changes in tissue oxygenation index (∆TOI) and total hemoglobin volume (∆tHb) of vastus lateralis and medialis muscles over 30 contractions were assessed by a near-infrared spectroscopy, and were compared between conditions by a two-way repeated measures ANOVA. Peak torque produced during EMS increased over 30 contractions in response to the increase in the stimulation intensity for pulsed current, but not for the alternating current EMS. The torque during each isometric contraction was less stable in alternating than pulsed current EMS. The changes in ∆TOI amplitude during relaxation phases and ∆tHb amplitude were not significantly different between conditions. However, the decreases in ∆TOI amplitude during contraction phases from baseline were significantly (P < 0.05) greater for the pulsed current than alternating current from the 18th contraction (-15.6 ± 2.3 vs. -8.9 ± 1.8%) to 30th contraction (-10.7 ± 1.8 vs. -4.8 ± 1.5%). These results suggest that the muscles were less activated in the alternating current EMS when compared with the pulsed current EMS.

[Isokinetic assessment with two years follow-up of anterior cruciate ligament reconstruction with patellar tendon or hamstring tendons].

PubMed

Condouret, J; Cohn, J; Ferret, J-M; Lemonsu, A; Vasconcelos, W; Dejour, D; Potel, J-F

2008-12-01

This retrospective multicentric study was designed to assess the outcome of quadriceps and hamstrings muscles two years after Anterior Cruciate Ligament (ACL) reconstruction and compare muscles recovery depending on the type of graft and individual variables like age, gender, level of sport, but also in terms of discomfort, pain and functional score. The results focused on the subjective and objective IKDC scores, SF36, the existence or not of subjective disorders and their location. The review included isokinetic muscle tests concentric and eccentric extensors/flexors but also internal rotators/external rotators with analysis of mean work and mean power. One hundred and twenty-seven patients were included with an average age 29 years (+/-10). They all had an ACL reconstruction with patellar tendon or hamstring tendon with single or double bundles. In the serie, the average muscles deficit at two years was 10% for the flexors and extensors but with a significant dispersion. Significant differences were not noted in the mean values of all parameters in term of sex or age (over 30 years or not), neither the type of sport, nor of clinical assessment (Class A and B of objective IKDC score), nor the existence of anterior knee pain. There was a relationship between the level of extensor or flexor recovery and the quality of functional results with minimal muscle deficits close to 5% if the IKDC score was over 90 and deficits falling to 15% in the group with IKDC score less than 90. The type of reconstruction (patellar tendon versus hamstrings) had an influence on the muscle deficit. For extensors, the recovery was the same in the two groups, more than 90% at two years and the distribution of these two populations by level of deficit was quite the same. For flexors, residual deficits were significantly higher in the hamstrings group on the three studied parameters whatever the speed and the type of contraction (concentric or eccentric) with an average deficit of 14 to 18%, while, in the patellar tendon group, there was a dominance over the opposite side of 2 to 3% in concentric contraction. The hamstrings deficit appears to be "harvest dependent". For internal rotators, a significantly higher deficit is observed in eccentric contraction for the hamstrings group. The residual hamstrings deficits were related to the number of tendons harvested: -7% when there was no harvest, 7% with one tendon harvested and 17% with two tendons harvested. The relationship between the level of recovery of the quadriceps muscle and hamstrings at two years and the quality of functional results incite, regarding the significantly higher deficit of flexors in ACL reconstructions with hamstrings, to change the rehabilitation programs and especially on early rehabilitation of hamstrings in eccentric mode in the early weeks postoperative considering the harvest site as an equivalent of muscle tear.

Referred pain from myofascial trigger points in head, neck, shoulder, and arm muscles reproduces pain symptoms in blue-collar (manual) and white-collar (office) workers.

PubMed

Fernández-de-las-Peñas, César; Gröbli, Christian; Ortega-Santiago, Ricardo; Fischer, Christine Stebler; Boesch, Daniel; Froidevaux, Philippe; Stocker, Lilian; Weissmann, Richard; González-Iglesias, Javier

2012-07-01

To describe the prevalence and referred pain area of trigger points (TrPs) in blue-collar (manual) and white-collar (office) workers, and to analyze if the referred pain pattern elicited from TrPs completely reproduces the overall spontaneous pain pattern. Sixteen (62% women) blue-collar and 19 (75% women) white-collar workers were included in this study. TrPs in the temporalis, masseter, upper trapezius, sternocleidomastoid, splenius capitis, oblique capitis inferior, levator scapulae, scalene, pectoralis major, deltoid, infraspinatus, extensor carpi radialis brevis and longus, extensor digitorum communis, and supinator muscles were examined bilaterally (hyper-sensible tender spot within a palpable taut band, local twitch response with snapping palpation, and elicited referred pain pattern with palpation) by experienced assessors blinded to the participants' condition. TrPs were considered active when the local and referred pain reproduced any symptom and the patient recognized the pain as familiar. The referred pain areas were drawn on anatomic maps, digitized, and measured. Blue-collar workers had a mean of 6 (SD: 3) active and 10 (SD: 5) latent TrPs, whereas white-collar workers had a mean of 6 (SD: 4) active and 11 (SD: 6) latent TrPs (P>0.548). No significant differences in the distribution of active and latent TrPs in the analyzed muscles between groups were found. Active TrPs in the upper trapezius, infraspinatus, levator scapulae, and extensor carpi radialis brevis muscles were the most prevalent in both groups. Significant differences in referred pain areas between muscles (P<0.001) were found; pectoralis major, infraspinatus, upper trapezius, and scalene muscles showed the largest referred pain areas (P<0.01), whereas the temporalis, masseter, and splenius capitis muscles showed the smallest (P<0.05). The combination of the referred pain from TrPs reproduced the overall clinical pain area in all participants. Blue-collar and white-collar workers exhibited a similar number of TrPs in the upper quadrant musculature. The referred pain elicited by active TrPs reproduced the overall pain pattern. The distribution of TrPs was not significantly different between groups. Clinicians should examine for the presence of muscle TrPs in blue-collar and white-collar workers.

Hand rest and wrist support are effective in preventing fatigue during prolonged typing.

PubMed

Callegari, Bianca; de Resende, Marília Maniglia; da Silva Filho, Manoel

Case series (longitudinal). Only few reports concerning the efficacy of commonly used strategies for preventing upper limb occupational disorders associated with prolonged typing exist. We aimed to investigate whether the duration of typing and the use of 2 strategies (hand rest and wrist support) changes muscle physiological response and therefore the electromyography records. We enrolled 25 volunteers, who were unfamiliar with the task and did not have musculoskeletal disorders. The subjects underwent 3 prolonged typing protocols to investigate the efficacy of the 2 adopted strategies in reducing the trapezius, biceps brachii, and extensor digitorum communis fatigue. Typing for 1 hour induced muscular fatigue (60%-67% of the subjects). The extensor digitorum communis muscle exhibited the highest percentage of fatigue (72%-84%) after 1 and 4 hours of typing (1 hour, P = .04; 4 hours, P = .02). Fatigue levels in this muscle were significantly reduced (24%) with the use of pause typing (4 hours, P = .045), whereas biceps brachii muscle fatigue was reduced (32%) only with the use of wrist supports (P = .02, after 4 hours). Trapezius muscle fatigue was unaffected by the tested occupational strategies (1 hour, P = .62; 4 hours, P = .85). Despite presenting an overall tendency for fatigue detected during the application of the protocols, the assessed muscles exhibited different behavior patterns, depending on both the preventive strategy applied and the muscle mechanical role during the task. Hand rest and wrist support can successfully reduce muscle fatigue in specific upper limb muscles during prolonged typing, leading to a muscle-selective reduction in the occurrence of fatigue and thus provide direct evidence that they may prevent work-related musculoskeletal disorders. N/A. Copyright © 2016 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Chest Press Exercises With Different Stability Requirements Result in Similar Muscle Damage Recovery in Resistance-Trained Men.

PubMed

Ferreira, Diogo V; Ferreira-Júnior, João B; Soares, Saulo R S; Cadore, Eduardo L; Izquierdo, Mikel; Brown, Lee E; Bottaro, Martim

2017-01-01

Ferreira, DV, Ferreira-Júnior, JB, Soares, SRS, Cadore, EL, Izquierdo, M, Brown, LE, and Bottaro, M. Chest press exercises with different stability requirements result in similar muscle damage recovery in resistance trained men. J Strength Cond Res 31(1): 71-79, 2017-This study investigated the time course of 96 hours of muscle recovery after 3 different chest press exercises with different stability requirements in resistance-trained men. Twenty-seven men (23.5 ± 3.8 years) were randomly assigned to one of the 3 groups: (a) Smith machine bench press; (b) barbell bench press; or (c) dumbbell bench press. Participants performed 8 sets of 10 repetition maximum with 2 minutes rest between sets. Muscle thickness, peak torque (PT), and soreness were measured pre, post, 24, 48, 72, and 96 hours after exercise. There were no differences in the time course of PT or muscle thickness values of the pectoralis major (p = 0.98 and p = 0.91, respectively) or elbow extensors (p = 0.07 and p = 0.86, respectively) between groups. Muscle soreness of the pectoralis major was also not different between groups (p > 0.05). However, the Smith machine and barbell groups recovered from triceps brachii muscle soreness by 72 hours after exercise (p > 0.05), whereas the dumbbell group did not present any triceps brachii muscle soreness after exercise (p > 0.05). In conclusion, resistance-trained men experience similar muscle damage recovery after Smith machine, barbell, and dumbbell chest press exercise. However, muscle soreness of the elbow extensors takes a longer time to recover after using a barbell chest press exercise.

Muscle Adaptations Following Short-Duration Bed Rest with Integrated Resistance, Interval, and Aerobic Exercise

NASA Technical Reports Server (NTRS)

Hackney, Kyle J.; Scott, Jessica M.; Buxton, Roxanne; Redd-Goetchius, Elizabeth; Crowell, J. Brent; Everett, Meghan E.; Wickwire, Jason; Ryder, Jeffrey W.; Bloomberg, Jacob J.; Ploutz-Snyder, Lori L.

2011-01-01

Unloading of the musculoskeletal system during space flight results in deconditioning that may impair mission-related task performance in astronauts. Exercise countermeasures have been frequently tested during bed rest (BR) and limb suspension; however, high-intensity, short-duration exercise prescriptions have not been fully explored. PURPOSE: To determine if a high intensity resistance, interval, and aerobic exercise program could protect against muscle atrophy and dysfunction when performed during short duration BR. METHODS: Nine subjects (1 female, 8 male) performed a combination of supine exercises during 2 weeks of horizontal BR. Resistance exercise (3 d / wk) consisted of squat, leg press, hamstring curl, and heel raise exercises (3 sets, 12 repetitions). Aerobic (6 d / wk) sessions alternated continuous (75% VO2 peak) and interval exercise (30 s, 2 min, and 4 min) and were completed on a supine cycle ergometer and vertical treadmill, respectively. Muscle volumes of the upper leg were calculated pre, mid, and post-BR using magnetic resonance imaging. Maximal isometric force (MIF), rate of force development (RFD), and peak power of the lower body extensors were measured twice before BR (averaged to represent pre) and once post BR. ANOVA with repeated measures and a priori planned contrasts were used to test for differences. RESULTS: There were no changes to quadriceps, hamstring, and adductor muscle volumes at mid and post BR time points compared to pre BR (Table 1). Peak power increased significantly from 1614 +/- 372 W to 1739 +/- 359 W post BR (+7.7%, p = 0.035). Neither MIF (pre: 1676 +/- 320 N vs. post: 1711 +/- 250 N, +2.1%, p = 0.333) nor RFD (pre: 7534 +/- 1265 N/ms vs. post: 6951 +/- 1241 N/ms, -7.7%, p = 0.136) were significantly impaired post BR.

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

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.

Two families with MYH7 distal myopathy associated with cardiomyopathy and core formations.

PubMed

Naddaf, Elie; Waclawik, Andrew J

2015-03-01

Laing distal myopathy is caused by MYH7 gene mutations. Multiple families have been reported with varying patterns of skeletal and cardiac involvement as well as histopathological findings. We report 2 families with p.Glu1508del mutation with detailed electrophysiological and muscle pathology findings. All patients displayed the classic phenotype with weakness starting in the anterior compartment of the legs with a "hanging great toe." It was followed by finger extensors involvement, relatively sparing the extensor indicis proprius, giving the appearance of a "pointing index" finger. All the affected individuals had a dilated cardiomyopathy and core formations on muscle biopsy. Unexpectedly, neurogenic changes were also observed in some individuals. Both families were initially misdiagnosed with either central core disease or hereditary neuropathy. Recognizing the classic phenotype, screening for cardiac involvement that may be clinically silent, and determining the mode of inheritance help with selecting the appropriate genetic test.

Surgical Treatment of Traumatic Myositis Ossificans of the Extensor Carpi Radialis Muscle in a Dog.

PubMed

Morton, Bridget A; Hettlich, Bianca F; Pool, Roy R

2015-07-01

To report clinical signs, diagnostic imaging findings, and outcome in a dog with traumatic myositis ossificans of the origin of the extensor carpi radialis muscle. Clinical report. An 8-month-old intact female Irish Setter Dog. After radiographic and computed tomographic evaluation of an osseous proliferation arising from the cranial cortex of the right distal humeral diaphysis, the protruding bone was surgically removed and evaluated by histopathology. Traumatic myositis ossificans was successfully treated with surgical removal of the osseous proliferation resulting in improved postoperative range of motion of the right elbow joint. There was no evidence of lameness or abnormal bone regrowth associated with the surgical site radiographically at follow up. Surgical removal of a traumatic myositis ossificans lesion resulted in full return to function in a young, competitive show dog. © Copyright 2014 by The American College of Veterinary Surgeons.

A dental stool with chest support reduces lower back muscle activation.

PubMed

Tran, Viet; Turner, Reid; MacFadden, Andrew; Cornish, Stephen M; Esliger, Dale; Komiyama, Kunio; Chilibeck, Philip D

2016-09-01

Activation of back musculature during work tasks leads to fatigue and potential injury. This is especially prevalent in dentists who perform much of their work from a seated position. We examined the use of an ergonomic dental stool with mid-sternum chest support for reducing lower back muscle activation. Electromyography of lower back extensors was assessed from 30 dental students for 20 s during three conditions in random order: (a) sitting upright at 90° of hip flexion on a standard stool, (b) leaning forward at 80° of hip flexion on a standard stool, and (c) leaning forward at 80° of hip flexion while sitting on an ergonomic stool. Muscular activity of the back extensors was reduced when using the ergonomic stool compared to the standard stool, by 33-50% (p < 0.01). This suggests a potential musculoskeletal benefit with use of a dental stool with mid-sternum chest support.

Depressed tetanic contactile function cannot be compensated by increasing stimulating frequency in unloaded soleus muscle

NASA Astrophysics Data System (ADS)

Gao, Fang; Yu, Zhi-Bin

2005-08-01

The weightlessness-induced muscle atrophy is associated with a reduced force and power and with an increased fatigability [1]. In prolonged manned space missions, these alterations in skeletal muscles could limit the crew's ability to work in space and to rapidly egress in an emergency on return to Earth. In order to elucidate the underlying mechanisms of the increased fatigability in the atrophic skeletal muscle, we isolated the typically fast and slow muscle, extensor digitorum longus (EDL) and soleus (SOL), to observe the changes in maximal contraction tension, optimal stimulating frequency, and recovery features after fatigue in the intermittent tetanic contraction.

Changes of muscle function and size with bedrest

NASA Technical Reports Server (NTRS)

Dudley, Gary A.; Gollnick, Philip D.; Convertino, Victor A.; Buchanan, Paul

1989-01-01

The impact of a short-term head-down bedrest on the skeletal-muscle function of humans was investigated in healthy males subjected (after five days of control period) to 30-day 6-deg head-down bed rest (BR) followed by a five-day recovery period. It was found that the head-down BR led to a decrease in force developed by the knee extensor muscle group during maximal voluntary efforts, with the average reduction of 21 percent across the speeds of concentric and eccentric muscle action. Significant decreases were also found in the cross-sectional areas of slow-twitch and fast-twitch muscle fibers of the vastus lateralis.

Association between muscle strength and metabolic syndrome in older Korean men and women: the Korean Longitudinal Study on Health and Aging.

PubMed

Yang, Eun Joo; Lim, Soo; Lim, Jae-Young; Kim, Ki Woong; Jang, Hak Chul; Paik, Nam-Jong

2012-03-01

The objective of the study was to investigate the association between metabolic syndrome (MS) and muscle strength in community-dwelling older men and women in Korea. Korean men and women 65 years and older living in a single, typical South Korean city (n = 647) were enrolled in the Korean Longitudinal Study on Health and Aging study. The diagnosis of MS was evaluated according to the definition of the National Cholesterol Education Program Adult Treatment Panel III. Isokinetic muscle strength of the knee extensors, as determined by peak torque per body weight (newton meter per kilogram) and hand-grip strength per body weight (newton per kilogram), was measured. Participants without MS had greater leg muscle strength and grip strength per weight. The effect of MS on muscle strength was more prominent in men than in women in our study population. Only men showed a significant interaction between MS and age for muscle strength (P = .014), and the effect was greater in men aged 65 to 74 years compared with those older than 75 years (119.2 ± 31.2 vs 134.5 ± 24.3 N m/kg). Participants with MS had weaker knee extensor strength after controlling the covariates (β = -90.80, P = .003), and the interaction term (age × MS × male sex) was significant (β = 1.00, P = .017). Metabolic syndrome is associated with muscle weakness, and this relationship is particularly pronounced in men. Age can modify the impact of MS on muscle strength. Men aged 65 to 74 years with MS need a thorough assessment of muscle strength to prevent disability. Copyright © 2012 Elsevier Inc. All rights reserved.

[Reconstruction of the extensor pollicis longus tendon by transposition of the extensor indicis tendon].

PubMed

Loos, A; Kalb, K; Van Schoonhoven, J; Landsleitner Dagger, B

2003-12-01

Rupture of the extensor pollicis longus-tendon (EPL) is a frequent complication after distal radius fractures. Other traumatic and non-traumatic reasons for this tendon lesion are known, including a theory about a disorder in the blood supply to the tendon itself. We examined 40 patients after reconstruction of the EPL-tendon in a mean follow-up time of 30 months. All patients were clinically examined and a DASH questionnaire was answered by all patients. The method to reconstruct the EPL-tendon was the transposition of the extensor indicis-tendon. After the operations the thumb was put in a splint for four weeks in a "hitch-hiker's-position". 31 ruptures of the tendon (77.5 %) were a result of trauma. In 20 of them (50 %) a distal radius fracture had occurred. Clinical examination included measurements of the movement of the thumb- and index-finger joints, the grip strength and the maximal span of the hand. Significant differences were not found. The isolated extension of the index finger was possible in all patients. But it was reduced in ten cases which represent 25 %. Our results were evaluated by the Geldmacher score to evaluate the reconstruction of the EPL-tendon. 20 % excellent, 65 % good, 12.5 % fair and 2.5 % poor results were reached. The Geldmacher score was used critically. We suggest its modification for the evaluation of thumb abduction. The DASH score reached a functional value of ten points which represents a very good result. In conclusion the extensor indicis-transposition is a safe method to reconstruct the EPL-tendon. Its substantial advantage is taking a healthy muscle as the motor, thereby avoiding the risk of using a degenerated muscle in late tendon reconstruction. A powerful extension of the index finger will be maintained by physical education. Generally, the loss of the extension of the index finger is negligible. It does not disturb the patients. But it has to be discussed with the patient before the operation.

Vibration-evoked reciprocal inhibition between human wrist muscles.

PubMed

Cody, F W; Plant, T

1989-01-01

Reciprocal inhibition of the voluntarily contracting wrist extensor (extensor carpi radialis, ECR) evoked by proprioceptive afferent input from the flexor (flexor carpi radialis, FCR), was studied in healthy human subjects. Vibration of the FCR tendon was used to elicit Ia-dominated afferent discharge whilst inhibition of ECR was assessed as the reduction in asynchronous, on-going EMG. A small early phase of inhibition (I1) was evident in 25% of trials. The latency (ca. 25 ms) of this component suggested that it was mediated by an Ia oligosynaptic. possibly 'classical' disynaptic, inhibitory pathway. A later and apparently separate phase of reduced activity (I2, ca. 40 ms) was, however, far more consistently observed (96% of trials) and of greater magnitude. The I2 component was usually followed, some 20 ms later, by a phase of elevated activity (E1, 72% trials). Reductions in simultaneously recorded net extensor torque commenced at about 60 ms following the onset of flexor tendon vibration, i.e. some 20 ms after the main I2 EMG component. These mechanical responses must have almost exclusively resulted from reciprocal inhibition of extensor EMG since vibration of the relaxed FCR evoked minimal excitatory flexor activity. The reflex pattern, in any individual subject, was relatively unaffected by altering the duration of the vibration train between one and nineteen cycles (125 Hz). This suggests that the entire response complex resulted largely from the initial afferent volley. The sizes of both the I1 and I2 reductions in ECR activity increased with increasing voluntary extensor contraction so that their depths remained constant proportions of background EMG. Very similar results were obtained when reciprocal inhibition of FCR was produced by vibration of the belly of ECR. Thus, reciprocal inhibition between wrist muscles is mainly expressed as a rather stereotyped, short duration reduction in EMG whose depth is determined by the pre-existing level of motor activity. Some functional implications of this form of reflex behaviour are discussed.

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

Forearm Muscle Oxygenation Decreases During Low Levels of Brief, Isometric Contraction

NASA Technical Reports Server (NTRS)

Murthy Gita; Kahan, N. J.; Hargens, Alan R.; Rempel, D. M.; Hargens, Murthy G. (Technical Monitor)

1997-01-01

Regional muscle pain syndromes can be caused by repeated and sustained exertion of a specific muscle. Such exertion may elevate local tissue fluid pressure, reduce blood flow and tissue oxygenation (TO2), and cause fatigue, pain and functional deficits of the Involved muscle. Low levels (less than 20% maximum voluntary contraction (MVC)) of prolonged static contraction of the upper extremity are common In many occupational settings and May cause fatigue. The purpose of our Investigation was to determine whether TO2 decreases significantly at low levels of static contraction of the extensor carpi radialis brevis (ECRB).

Comparison of electromyographic activity and range of neck motion in violin students with and without neck pain during playing.

PubMed

Park, Kyue-nam; Kwon, Oh-yun; Ha, Sung-min; Kim, Su-jung; Choi, Hyun-jung; Weon, Jong-hyuck

2012-12-01

Neck pain is common in violin students during a musical performance. The purpose of this study was to compare electromyographic (EMG) activity in superficial neck muscles with neck motion when playing the violin as well as neck range of motion (ROM) at rest, between violin students with and without neck pain. Nine violin students with neck pain and nine age- and gender-matched subjects without neck pain were recruited. Muscle activity of the bilateral upper trapezius, sternocleidomastoid, and superficial cervical extensor muscles was measured using surface EMG. Kinematic data on neck motion while playing and active neck ROM were also measured using a three-dimensional motion analysis system. Independent t-tests were used to compare EMG activity with kinematic data between groups. These analyses revealed that while playing, both the angle of left lateral bending and leftward rotation of the cervical spine were significantly greater in the neck pain group than among those without neck pain. Similarly, EMG activity of the left upper trapezius, both cervical extensors, and both sternocleidomastoid muscles were significantly greater in the neck pain group. The active ROM of left axial rotation was significantly lower in the neck pain group. These results suggest that an asymmetric playing posture and the associated increased muscle activity as well as decreased neck axial rotation may contribute to neck pain in violin students.

Mid-thigh cortical bone structural parameters, muscle mass and strength, and association with lower limb fractures in older men and women (AGES-Reykjavik Study).

PubMed

Johannesdottir, Fjola; Aspelund, Thor; Siggeirsdottir, Kristin; Jonsson, Brynjolfur Y; Mogensen, Brynjolfur; Sigurdsson, Sigurdur; Harris, Tamara B; Gudnason, Vilmundur G; Lang, Thomas F; Sigurdsson, Gunnar

2012-05-01

In a cross-sectional study we investigated the relationship between muscle and bone parameters in the mid-thigh in older people using data from a single axial computed tomographic section through the mid-thigh. Additionally, we studied the association of these variables with incident low-trauma lower limb fractures. A total of 3,762 older individuals (1,838 men and 1,924 women), aged 66-96 years, participants in the AGES-Reykjavik study, were studied. The total cross-sectional muscular area and knee extensor strength declined with age similarly in both sexes. Muscle parameters correlated most strongly with cortical area and total shaft area (adjusted for age, height, and weight) but explained <10 % of variability in those bone parameters. The increment in medullary area (MA) and buckling ratio (BR) with age was almost fourfold greater in women than men. The association between MA and muscle parameters was nonsignificant. During a median follow-up of 5.3 years, 113 women and 66 men sustained incident lower limb fractures. Small muscular area, low knee extensor strength, large MA, low cortical thickness, and high BR were significantly associated with fractures in both sexes. Our results show that bone and muscle loss proceed at different rates and with different gender patterns.

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.

Hip muscle strength is decreased in middle-aged recreational male athletes with midportion Achilles tendinopathy: A cross-sectional study.

PubMed

Habets, B; Smits, H W; Backx, F J G; van Cingel, R E H; Huisstede, B M A

2017-05-01

Investigating differences in hip muscle strength between athletes with Achilles tendinopathy (AT) and asymptomatic controls. Cross-sectional case-control study. Sports medical center. Twelve recreational male athletes with mid-portion AT and twelve matched asymptomatic controls. Isometric strength of the hip abductors, external rotators, and extensors was measured using a handheld dynamometer. Functional hip muscle performance was evaluated with the single-leg squat. The Victorian Institute of Sport Assessment-Achilles (VISA-A) questionnaire was completed to determine clinical severity of symptoms. Compared to controls, participants with AT demonstrated 28.9% less isometric hip abduction strength (p = 0.012), 34.2% less hip external rotation strength (p = 0.010), and 28.3% less hip extension strength (p = 0.034) in the injured limb. Similar differences were found for the non-injured limb (26.7-41.8%; p < 0.03). No significant differences were found in functional hip muscle performance between the injured and non-injured limb or between the groups, and no significant correlation was found between hip muscle strength and VISA-A scores. Recreational male athletes with chronic mid-portion AT demonstrated bilateral weakness of hip abductors, external rotators, and extensors compared to their asymptomatic counterparts. These findings suggest that hip muscle strength may be important in the assessment and rehabilitation of those with AT. Copyright © 2016 Elsevier Ltd. All rights reserved.

Longitudinal sensitivity to change of MRI-based muscle cross-sectional area versus isometric strength analysis in osteoarthritic knees with and without structural progression: pilot data from the Osteoarthritis Initiative.

PubMed

Dannhauer, Torben; Sattler, Martina; Wirth, Wolfgang; Hunter, David J; Kwoh, C Kent; Eckstein, Felix

2014-08-01

Biomechanical measurement of muscle strength represents established technology in evaluating limb function. Yet, analysis of longitudinal change suffers from relatively large between-measurement variability. Here, we determine the sensitivity to change of magnetic resonance imaging (MRI)-based measurement of thigh muscle anatomical cross sectional areas (ACSAs) versus isometric strength in limbs with and without structural progressive knee osteoarthritis (KOA), with focus on the quadriceps. Of 625 "Osteoarthritis Initiative" participants with radiographic KOA, 20 had MRI cartilage and radiographic joint space width loss in the right knee isometric muscle strength measurement and axial T1-weighted spin-echo acquisitions of the thigh. Muscle ACSAs were determined from manual segmentation at 33% femoral length (distal to proximal). In progressor knees, the reduction in quadriceps ACSA between baseline and 2-year follow-up was -2.8 ± 7.9 % (standardized response mean [SRM] = -0.35), and it was -1.8 ± 6.8% (SRM = -0.26) in matched, non-progressive KOA controls. The decline in extensor strength was more variable than that in ACSAs, both in progressors (-3.9 ± 20%; SRM = -0.20) and in non-progressive controls (-4.5 ± 28%; SRM = -0.16). MRI-based analysis of quadriceps muscles ACSAs appears to be more sensitive to longitudinal change than isometric extensor strength and is suggestive of greater loss in limbs with structurally progressive KOA than in non-progressive controls.

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.

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.

Feed-forward motor control of ultrafast, ballistic movements.

PubMed

Kagaya, K; Patek, S N

2016-02-01

To circumvent the limits of muscle, ultrafast movements achieve high power through the use of springs and latches. The time scale of these movements is too short for control through typical neuromuscular mechanisms, thus ultrafast movements are either invariant or controlled prior to movement. We tested whether mantis shrimp (Stomatopoda: Neogonodactylus bredini) vary their ultrafast smashing strikes and, if so, how this control is achieved prior to movement. We collected high-speed images of strike mechanics and electromyograms of the extensor and flexor muscles that control spring compression and latch release. During spring compression, lateral extensor and flexor units were co-activated. The strike initiated several milliseconds after the flexor units ceased, suggesting that flexor activity prevents spring release and determines the timing of strike initiation. We used linear mixed models and Akaike's information criterion to serially evaluate multiple hypotheses for control mechanisms. We found that variation in spring compression and strike angular velocity were statistically explained by spike activity of the extensor muscle. The results show that mantis shrimp can generate kinematically variable strikes and that their kinematics can be changed through adjustments to motor activity prior to the movement, thus supporting an upstream, central-nervous-system-based control of ultrafast movement. Based on these and other findings, we present a shishiodoshi model that illustrates alternative models of control in biological ballistic systems. The discovery of feed-forward control in mantis shrimp sets the stage for the assessment of targets, strategic variation in kinematics and the role of learning in ultrafast animals. © 2016. Published by The Company of Biologists Ltd.

The reliability and validity of a designed setup for the assessment of static back extensor force and endurance in older women with and without hyperkyphosis.

PubMed

Roghani, Taybeh; Khalkhali Zavieh, Minoo; Rahimi, Abbas; Talebian, Saeed; Manshadi, Farideh Dehghan; Akbarzadeh Baghban, Alireza; King, Nicole; Katzman, Wendy

2018-01-25

The purpose of this study was to investigate the intra-rater reliability and validity of a designed load cell setup for the measurement of back extensor muscle force and endurance. The study sample included 19 older women with hyperkyphosis, mean age 67.0 ± 5.0 years, and 14 older women without hyperkyphosis, mean age 63.0 ± 6.0 years. Maximum back extensor force and endurance were measured in a sitting position with a designed load cell setup. Tests were performed by the same examiner on two separate days within a 72-hour interval. The intra-rater reliability of the measurements was analyzed using intraclass correlation coefficient (ICC), standard errors of measurement (SEM), and minimal detectable change (MDC). The validity of the setup was determined using Pearson correlation analysis and independent t-test. Using our designed load cell, the values of ICC indicated very high reliability of force measurement (hyperkyphosis group: 0.96, normal group: 0.97) and high reliability of endurance measurement (hyperkyphosis group: 0.82, normal group: 0.89). For all tests, the values of SEM and MDC were low in both groups. A significant correlation between two documented forces (load cell force and target force) and significant differences in the muscle force and endurance among the two groups were found. The measurements of static back muscle force and endurance are reliable and valid with our designed setup in older women with and without hyperkyphosis.

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

BIOMECHANICAL DIFFERENCES IN BRAZILIAN JIU-JITSU ATHLETES: THE ROLE OF COMBAT STYLE

PubMed Central

Lima, Alane Almeida; Coelho, Anita Camila Sampaio; Lima, Yuri Lopes; Almeida, Gabriel Peixoto Leão; Bezerra, Márcio Almeida; de Oliveira, Rodrigo Ribeiro

2017-01-01

Background Brazilian Jiu-Jitsu (BJJ) athletes can be divided into two combat styles: pass fighters (PFs) and guard fighters (GFs). Flexibility of the posterior chain muscles is highly necessary in these athletes, especially in GFs. On the other hand, isometric strength of the trunk extensors is required in PFs. Handgrip strength is important in holding the kimono of the opponent, and symmetrical lower-limb strength is important for the prevention of injuries due to the overload caused by training. Purpose The aim of this study was to compare the biomechanical profiles of BJJ athletes with different combat styles using the following outcome measures: flexibility, trunk extensor isometric endurance, postural balance, handgrip isometric endurance and lower-limb muscle strength. Methods A cross-sectional study was conducted using 19 GFs and 19 PFs. The sit-and-reach test was used to evaluate the flexibility of the posterior chain muscles. The Biodex Balance System® was used to evaluate balance. A handgrip dynamometer and a dorsal dynamometer were used to evaluate handgrip and trunk extensor endurance, respectively. Quadriceps and hamstring strength were evaluated with an isokinetic dynamometer at 60 °/s. Results No differences were observed between groups in terms of flexibility, balance, handgrip isometric endurance or quadriceps and hamstring strength; however, PFs (81.33) showed more isometric trunk extension endurance than GFs (68.85) (p = 0.02). Both groups had low values for hamstring/quadriceps ratio. Conclusion No significant biomechanical differences were observed between PFs and GFs. Level of Evidence 2b PMID:28217417

Functional anatomy of the cheetah (Acinonyx jubatus) forelimb

PubMed Central

Hudson, Penny E; Corr, Sandra A; Payne-Davis, Rachel C; Clancy, Sinead N; Lane, Emily; Wilson, Alan M

2011-01-01

Despite the cheetah being the fastest living land mammal, we know remarkably little about how it attains such high top speeds (29 m s−1). Here we aim to describe and quantify the musculoskeletal anatomy of the cheetah forelimb and compare it to the racing greyhound, an animal of similar mass, but which can only attain a top speed of 17 m s−1. Measurements were made of muscle mass, fascicle length and moment arms, enabling calculations of muscle volume, physiological cross-sectional area (PCSA), and estimates of joint torques and rotational velocities. Bone lengths, masses and mid-shaft cross-sectional areas were also measured. Several species differences were observed and have been discussed, such as the long fibred serratus ventralis muscle in the cheetah, which we theorise may translate the scapula along the rib cage (as has been observed in domestic cats), thereby increasing the cheetah's effective limb length. The cheetah's proximal limb contained many large PCSA muscles with long moment arms, suggesting that this limb is resisting large ground reaction force joint torques and therefore is not functioning as a simple strut. Its structure may also reflect a need for control and stabilisation during the high-speed manoeuvring in hunting. The large digital flexors and extensors observed in the cheetah forelimb may be used to dig the digits into the ground, aiding with traction when galloping and manoeuvring. PMID:21332715

Agonist contraction during intermittent theta burst stimulation enhances motor cortical plasticity of the wrist flexors.

PubMed

Mirdamadi, J L; Suzuki, L Y; Meehan, S K

2015-03-30

Differences in cortical control across the different muscles of the upper limb may mitigate the efficacy of TMS interventions targeting a specific muscle. The current study sought to determine whether weak concurrent contraction during TMS could enhance the efficacy of intermittent theta burst stimulation (iTBS) in the forearm flexors. Motor evoked potentials (MEP) were elicited from the flexor (FCR) and extensor carpi radialis (ECR) motor cortical hotspots before and after iTBS over the FCR cortical hotspot. During iTBS the FCR was either relaxed (iTBS-Relax) or tonically contracted to 10% of maximum voluntary force (iTBS-Contract). iTBS-Relax failed to produce consistent potentiation of MEPFCR amplitude. Individuals with a relatively lower RMTFCR compared RMTECR demonstrated MEPFCR facilitation post-iTBS-Relax. Individuals with relatively higher RMTFCR demonstrated less facilitation and even suppression of MEPFCR amplitude. iTBS-Contract facilitated MEPFCR amplitude but only for MEPFCR evoked from the ECR hotspot. Interactions between overlapping cortical representations determine the efficacy of iTBS. Tonic contraction increases the efficacy of iTBS by enhancing the volume of the cortical representation. However, metaplastic effects may attenuate the enhancement of MEP gain at the motor cortical hotspot. The use of TMS as an adjunct to physical therapy should account for inter-muscle interactions when targeting muscles of the forearm. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Relationship between physical function and biomechanical gait patterns in boys with haemophilia.

PubMed

Stephensen, D; Taylor, S; Bladen, M; Drechsler, W I

2016-11-01

The World Federation of Haemophilia recommends joint and muscle health is evaluated using X-ray and magnetic resonance imaging, together with clinical examination scores. To date, inclusion of performance-based functional activities to monitor children with the condition has received little attention. To evaluate test-retest repeatability of physical function tests and quantify relationships between physical function, lower limb muscle strength and gait patterns in young boys with haemophilia. Timed 6-minute walk, timed up and down stairs, timed single leg stance, muscle strength of the knee extensors, ankle dorsi and plantar flexors, together with joint biomechanics during level walking were collected from 21 boys aged 6-12 years with severe haemophilia. Measures of physical function and recording of muscle strength with a hand-held myometer were repeatable (ICC > 0.78). Distances walked in six minutes, time taken to go up and down a flight of stairs and lower limb muscle strength correlated closely with ankle range of motion, together with peak knee flexion and ankle dorsi and plantarflexion moments during walking (P < 0.05). Alterations in gait patterns of boys with haemophilia appear to be associated with changes in performance of physical function and performance seems to depend on their muscle strength. Timed 6-minute walk test, timed up and down steps test and muscle strength of the knee extensors showed the strongest correlation with biomechanical joint function, and hence might serve as a basis for the clinical monitoring of physical function outcomes in children with haemophilia. © 2016 John Wiley & Sons Ltd.

Relations between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy.

PubMed

Eken, Maaike M; Houdijk, Han; Doorenbosch, Caroline A M; Kiezebrink, Francisca E M; van Bennekom, Coen A M; Harlaar, Jaap; Dallmeijer, Annet J

2016-08-01

To investigate the relation between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy (CP) and peers with typical development. In this case-control study, knee extensor muscle endurance was estimated from individual load-endurance curves as the load corresponding to a 15-repetition maximum in 17 adolescents with spastic CP (six males, 11 females; age 12-19y) and 18 adolescents with typical development (eight males, 10 females; age 13-19y). Questionnaires were used to assess subjectively reported fatigue (Pediatric Quality of Life Inventory Multidimensional Fatigue Scale) and participation (Life-Habits questionnaire). Walking capacity was assessed using the 6-minute walk test. Relations were determined using multiple regression analyses. Muscle endurance related significantly to subjectively reported fatigue and walking capacity in adolescents with CP, while no relations were found for adolescents with typical development (subjectively reported fatigue: regression coefficient β [95% confidence intervals] for CP=23.72 [6.26 to 41.18], for controls=2.72 [-10.26 to 15.69]; walking capacity β for CP=125m [-87 to 337], for controls=2m [-86 to 89]). The 15-repetition maximum did not relate to participation in adolescents with CP. Subjectively reported fatigue and reduced walking capacity in adolescents with CP are partly caused by lower muscle endurance of knee extensors. Training of muscle endurance might contribute to reducing the experience of fatigue and improving walking capacity. Reduced muscle endurance seems to have no effect on participation. © 2016 Mac Keith Press.

Clinical Implications for Muscle Strength Differences in Women of Different Age and Racial Groups: The WIN Study.

PubMed

Trudelle-Jackson, Elaine; Ferro, Emerenciana; Morrow, James R

2011-01-01

BACKGROUND: Reduction in muscle strength is strongly associated with functional decline in women, and women with lower quadriceps strength adjusted for body weight are more likely to develop knee osteoarthritis. OBJECTIVE: To compare body weight--adjusted strength among women of different age/racial groups. STUDY DESIGN: Cross-sectional study of muscle strength in 918 women aged 20--83 (M ± SD = 52 ± 13). METHODS: An orthopedic examination was conducted including measurement of handgrip and lower extremity strength (hip abductors/external rotators, knee flexors/extensors). Data were grouped into young (20--39 years, n = 139), middle (40--54 years, n = 300), and older (55+ years, n = 424) ages for white (n = 699) and African American (AA) (n = 164) women. Means and standard deviations for strength adjusted for body weight were calculated for each age and racial group and compared using 2-way multivariate analysis of variance and post hoc tests. RESULTS: No significant age-by-race interaction (P = .092) but significant main effects for age and race (P < .001). Pairwise comparisons revealed significant differences in knee extensor and flexor strength between all age groups. For grip and hip external rotator strength, significant differences were found between the middle and older groups. Differences in hip abductor strength were found between the young and middle-aged groups. AA women had lower strength than white women in all muscle groups (P < .05) except hip external rotators. CONCLUSIONS: Strength decreased with age in all muscle groups but magnitude of decrease varied by muscle. Strengthening programs should target different muscles, depending on a woman's age and race.

Effect of inaction on function of fast and slow muscle spindles

NASA Technical Reports Server (NTRS)

Arutyunyan, R. S.

1980-01-01

There is no data on the comparative effect of tenotomy on the function of the muscle spindles of fast and slow muscles. This study covers this question. The experiments were conducted on cats. The musuculus extensor digitorum longus (m. EDL) was selected as the fast muscle, and the musculus soleus (m. Sol.) as the slow. In a comparison of the spontaneous activity of primary and secondary endings of the fast and slow muscle spindles (i.e., the activity with complete relaxation of the muscles) normally no difference between them was successfully found. The authors recorded the integrative, and not the individual activity, and secondly, under conditions of such recording technique, those slight changes that are observed in the fast muscle receptors could remain unnoticed.

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.

Velocity associated characteristics of force production in college weight lifters.

PubMed

Kanehisa, H; Fukunaga, T

1999-04-01

To determine velocity specific isokinetic forces and cross sectional areas of reciprocal muscle groups in Olympic weight lifters. The cross sectional area of the flexor or extensor muscles of the elbow or knee joint was determined by a B-mode ultrasonic apparatus in 34 college weight lifters and 31 untrained male subjects matched for age. Maximum voluntary force produced in the flexion and extension of the elbow and knee joints was measured on an isokinetic dynamometer at 60, 180, and 300 degrees/s. The average cross sectional area was 31-65% higher, and the force was 19-62% higher in weight lifters than in the untrained subjects. The ratio of force to cross sectional area was the same in both groups. The weight lifters showed a lower velocity associated decline in force than untrained subjects in the elbow and knee flexors but not in the extensors. These results indicate that for muscle contractions with velocities between 60 degrees/s and 300 degrees/s the difference in isokinetic force between weight lifters and untrained subjects can be primarily attributed to the difference in the muscle cross sectional area. However, the lower velocity associated decline in force implies that weight lifters may have a higher force per cross sectional area than untrained subjects at velocities above 300 degrees/s.

Cellular properties of extensor carpi radialis brevis and trapezius muscles in healthy males and females.

PubMed

Green, Howard J; Ranney, Don; Burnett, Margaret; Iqbal, Sobia; Kyle, Natasha; Lounsbury, David; Ouyang, Jing; Tupling, A Russell; Smith, Ian C; Stewart, Riley; Tick, Heather

2015-11-01

In this study, we sought to determine whether differences in cellular properties associated with energy homeostasis could explain the higher incidence of work-related myalgia in trapezius (TRAP) compared with extensor carpi radialis brevis (ECRB). Tissue samples were obtained from the ECRB (n = 19) and TRAP (n = 17) of healthy males and females (age 27.9 ± 2.2 and 28.1 ± 1.5 years, respectively; mean ± SE) and analyzed for properties involved in both ATP supply and utilization. The concentration of ATP and the maximal activities of creatine phosphokinase, phosphorylase, and phosphofructokinase were higher (P < 0.05) in ECRB than TRAP. Succinic dehydrogenase, citrate synthase, and cytochrome c oxidase were not different between muscles. The ECRB also displayed a higher concentration of Na(+)-K(+)-ATPase and greater sarcoplasmic reticulum Ca(2+) release and uptake. No differences existed between muscles for either monocarboxylate transporters or glucose transporters. It is concluded that the potentials for high-energy phosphate transfer, glycogenolysis, glycolysis, and excitation-contraction coupling are higher in ECRB than TRAP. Histochemical measurements indicated that the muscle differences are, in part, related to differing amounts of type II tissue. Depending on the task demands, the TRAP may experience a greater metabolic and excitation-contraction coupling strain than the ECRB given the differences observed.

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.

Vibration influence on control of single motor unit activity.

PubMed

Malouin, F; Simard, T

1978-03-01

Effects of vibratory stimulation and maximal isometric contraction on a fine motor control task were evaluated in 17 human subjects. Electromyographic audiovisual feedback cues derived from two fine-wire bipolar electrodes, inserted to a depth of 12 and 6 mm respectively, were used to train the subjects to isolate a motor unit in the extensor carpi radialis brevis muscle. A specially designed compressed air driven vibrator providing vibratory stimulation with an amplitude of 2 mm and a frequency range of 120-160 cycles per second was applied to the muscle tendon. A significant decrease was found in the subjects; ability to isolate the pretest motor unit during and after continuous and interrupted periods of vibration and following a maximal isometric contraction of the extensor carpi radials brevis muscle. Individual variations in the subjects' responses to the forms of application of the vibratory stimulus, electrode preference and feedback specificity were observed. Results suggest that marked spatial recruitment of motor units, brought into action by the vibration stimulus or by the maximal isometric contraction, interfered with inhibitory mechanisms necessary to achieve isolation and control of a single motor unit. A therapeutic application of vibration, based on the marked spatial recruitment observed during and after vibration, is proposed for muscle reeducation.

Reliability and Validity of a New Method for Isometric Back Extensor Strength Evaluation Using A Hand-Held Dynamometer.

PubMed

Park, Hee-Won; Baek, Sora; Kim, Hong Young; Park, Jung-Gyoo; Kang, Eun Kyoung

2017-10-01

To investigate the reliability and validity of a new method for isometric back extensor strength measurement using a portable dynamometer. A chair equipped with a small portable dynamometer was designed (Power Track II Commander Muscle Tester). A total of 15 men (mean age, 34.8±7.5 years) and 15 women (mean age, 33.1±5.5 years) with no current back problems or previous history of back surgery were recruited. Subjects were asked to push the back of the chair while seated, and their isometric back extensor strength was measured by the portable dynamometer. Test-retest reliability was assessed with intraclass correlation coefficient (ICC). For the validity assessment, isometric back extensor strength of all subjects was measured by a widely used physical performance evaluation instrument, BTE PrimusRS system. The limit of agreement (LoA) from the Bland-Altman plot was evaluated between two methods. The test-retest reliability was excellent (ICC=0.82; 95% confidence interval, 0.65-0.91). The Bland-Altman plots demonstrated acceptable agreement between the two methods: the lower 95% LoA was -63.1 N and the upper 95% LoA was 61.1 N. This study shows that isometric back extensor strength measurement using a portable dynamometer has good reliability and validity.

Longitudinal, lateral and transverse axes of forearm muscles influence the crosstalk in the mechanomyographic signals during isometric wrist postures.

PubMed

Islam, Md Anamul; Sundaraj, Kenneth; Ahmad, R Badlishah; Sundaraj, Sebastian; Ahamed, Nizam Uddin; Ali, Md Asraf

2014-01-01

In mechanomyography (MMG), crosstalk refers to the contamination of the signal from the muscle of interest by the signal from another muscle or muscle group that is in close proximity. The aim of the present study was two-fold: i) to quantify the level of crosstalk in the mechanomyographic (MMG) signals from the longitudinal (Lo), lateral (La) and transverse (Tr) axes of the extensor digitorum (ED), extensor carpi ulnaris (ECU) and flexor carpi ulnaris (FCU) muscles during isometric wrist flexion (WF) and extension (WE), radial (RD) and ulnar (UD) deviations; and ii) to analyze whether the three-directional MMG signals influence the level of crosstalk between the muscle groups during these wrist postures. Twenty, healthy right-handed men (mean ± SD: age = 26.7±3.83 y; height = 174.47±6.3 cm; mass = 72.79±14.36 kg) participated in this study. During each wrist posture, the MMG signals propagated through the axes of the muscles were detected using three separate tri-axial accelerometers. The x-axis, y-axis, and z-axis of the sensor were placed in the Lo, La, and Tr directions with respect to muscle fibers. The peak cross-correlations were used to quantify the proportion of crosstalk between the different muscle groups. The average level of crosstalk in the MMG signals generated by the muscle groups ranged from: 34.28-69.69% for the Lo axis, 27.32-52.55% for the La axis and 11.38-25.55% for the Tr axis for all participants and their wrist postures. The Tr axes between the muscle groups showed significantly smaller crosstalk values for all wrist postures [F (2, 38) = 14-63, p<0.05, η2 = 0.416-0.769]. The results may be applied in the field of human movement research, especially for the examination of muscle mechanics during various types of the wrist postures.

Effects of hand configuration on muscle force coordination, co-contraction and concomitant intermuscular coupling during maximal isometric flexion of the fingers.

PubMed

Charissou, Camille; Amarantini, David; Baurès, Robin; Berton, Eric; Vigouroux, Laurent

2017-11-01

The mechanisms governing the control of musculoskeletal redundancy remain to be fully understood. The hand is highly redundant, and shows different functional role of extensors according to its configuration for a same functional task of finger flexion. Through intermuscular coherence analysis combined with hand musculoskeletal modelling during maximal isometric hand contractions, our aim was to better understand the neural mechanisms underlying the control of muscle force coordination and agonist-antagonist co-contraction. Thirteen participants performed maximal isometric flexions of the fingers in two configurations: power grip (Power) and finger-pressing on a surface (Press). Hand kinematics and force/moment measurements were used as inputs in a musculoskeletal model of the hand to determine muscular tensions and co-contraction. EMG-EMG coherence analysis was performed between wrist and finger flexors and extensor muscle pairs in alpha, beta and gamma frequency bands. Concomitantly with tailored muscle force coordination and increased co-contraction between Press and Power (mean difference: 48.08%; p < 0.05), our results showed muscle-pair-specific modulation of intermuscular coupling, characterized by pair-specific modulation of EMG-EMG coherence between Power and Press (p < 0.05), and a negative linear association between co-contraction and intermuscular coupling for the ECR/FCR agonist-antagonist muscle pair (r = - 0.65; p < 0.05). This study brings new evidence that pair-specific modulation of EMG-EMG coherence is related to modulation of muscle force coordination during hand contractions. Our results highlight the functional importance of intermuscular coupling as a mechanism contributing to the control of muscle force synergies and agonist-antagonist co-contraction.

Cervical muscle area measurements in acute whiplash patients and controls.

PubMed

Ulbrich, Erika J; Anderson, Suzanne E; Busato, Andre; Abderhalden, Susanne; Boesch, Chris; Zimmermann, Heinz; Heini, Paul; Hodler, Juerg; Sturzenegger, Matthias

2011-03-01

To quantitatively compare the muscle cross-sectional areas (CSAs) of the cervical muscles in symptomatic acute whiplash patients versus healthy controls. We hypothesized, that symptomatic whiplash patients have smaller cervical muscle CSAs than matched controls and that smaller cervical muscle CSAs in women might explain that women more frequently are symptomatic after whiplash injury than men. Prospective controlled study. Thirty-eight consecutive acute whiplash patients were examined within 48 h after a motor vehicle accident and 38 healthy age- and sex-matched controls, each half female, half male, were examined with the same protocol. MRI CSA measurements were performed of the deep and total cervical extensor muscles as well as the sternocleidomastoid muscles using transversal STIR (Short T1 Inversion Recovery) sequences on level C2, C4, and C5 by two blinded raters. Clinical symptoms were assessed with patient questionnaires (EuroQuol 5D, Specific Whiplash Questionnaire, head- and neck pain intensity [VAS]). Agreement of measurements between the two raters was high (intraclass correlation 0.52 to 0.85 for the different levels). No significant difference in age and body mass index were seen between patients and controls and the distribution of genders across groups was identical. There were no significant differences between patients and controls for all CSAs. Women had consistently smaller CSAs than men. The CSAs showed no significant correlation with the pain intensity of neck pain and headache but a consistent tendency of less neck pain and more headache with greater CSAs. This small study provides no evidence that subjects with smaller CSAs of cervical extensor muscles have a higher risk in developing symptoms after a whiplash injury and confirms smaller CSA in women. Copyright © 2011 Wiley-Liss, Inc.

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

Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1.

PubMed

Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; Richter, Erik A; Jensen, Thomas E

2015-02-01

Rac1 regulates stretch-stimulated (i.e. mechanical stress) glucose transport in muscle. Actin depolymerization decreases stretch-induced glucose transport in skeletal muscle. Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. An alternative to the canonical insulin signalling pathway for glucose transport is muscle contraction/exercise. Mechanical stress is an integrated part of the muscle contraction/relaxation cycle, and passive stretch stimulates muscle glucose transport. However, the signalling mechanism regulating stretch-stimulated glucose transport is not well understood. We recently reported that the actin cytoskeleton regulating GTPase, Rac1, was activated in mouse muscle in response to stretching. Rac1 is a regulator of contraction- and insulin-stimulated glucose transport, however, its role in stretch-stimulated glucose transport and signalling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle-specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton in isolated soleus and extensor digitorum longus muscles. In addition, the role of Rac1 in contraction-stimulated glucose transport during conditions without mechanical load on the muscles was evaluated in loosely hanging muscles and muscles in which cross-bridge formation was blocked by the myosin ATPase inhibitors BTS and Blebbistatin. Knockout as well as pharmacological inhibition of Rac1 reduced stretch-stimulated glucose transport by 30-50% in soleus and extensor digitorum longus muscle. The actin depolymerizing agent latrunculin B similarly decreased glucose transport in response to stretching by 40-50%. Rac1 inhibition reduced contraction-stimulated glucose transport by 30-40% in tension developing muscle but did not affect contraction-stimulated glucose transport in muscles in which force development was prevented. Our findings suggest that Rac1 and the actin cytoskeleton regulate stretch-stimulated glucose transport and that Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1

PubMed Central

Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; Richter, Erik A; Jensen, Thomas E

2015-01-01

An alternative to the canonical insulin signalling pathway for glucose transport is muscle contraction/exercise. Mechanical stress is an integrated part of the muscle contraction/relaxation cycle, and passive stretch stimulates muscle glucose transport. However, the signalling mechanism regulating stretch-stimulated glucose transport is not well understood. We recently reported that the actin cytoskeleton regulating GTPase, Rac1, was activated in mouse muscle in response to stretching. Rac1 is a regulator of contraction- and insulin-stimulated glucose transport, however, its role in stretch-stimulated glucose transport and signalling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle-specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton in isolated soleus and extensor digitorum longus muscles. In addition, the role of Rac1 in contraction-stimulated glucose transport during conditions without mechanical load on the muscles was evaluated in loosely hanging muscles and muscles in which cross-bridge formation was blocked by the myosin ATPase inhibitors BTS and Blebbistatin. Knockout as well as pharmacological inhibition of Rac1 reduced stretch-stimulated glucose transport by 30–50% in soleus and extensor digitorum longus muscle. The actin depolymerizing agent latrunculin B similarly decreased glucose transport in response to stretching by 40–50%. Rac1 inhibition reduced contraction-stimulated glucose transport by 30–40% in tension developing muscle but did not affect contraction-stimulated glucose transport in muscles in which force development was prevented. Our findings suggest that Rac1 and the actin cytoskeleton regulate stretch-stimulated glucose transport and that Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. Key points Rac1 regulates stretch-stimulated (i.e. mechanical stress) glucose transport in muscle. Actin depolymerization decreases stretch-induced glucose transport in skeletal muscle. Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. PMID:25416624

Effect of hypnotic suggestion on knee extensor neuromuscular properties in resting and fatigued states

PubMed Central

Antonini Philippe, Roberta; Guglielmo, Luiz Guilherme A.

2018-01-01

Purpose The aim of this study was to investigate whether hypnotic suggestions can alter knee extensor neuromuscular function at rest and during exercise. Methods Thirteen healthy volunteers (8 men and 5 women, 27 ± 3 years old) took part in this counterbalanced, crossover study including two experimental (hypnosis and control) sessions. Knee extensor neuromuscular function was tested before and after hypnosis suggestion by using a combination of voluntary contraction, transcutaneous femoral nerve electrical stimulation and transcranial magnetic stimulation (TMS). A fatiguing exercise (sustained submaximal contraction at 20% maximal voluntary contraction (MVC) force) was also performed to evaluate the potential influence of hypnosis on the extent and origin of neuromuscular adjustments. Results Hypnosis did not (p>0.05) alter MVC force or knee extensor neural properties. Corticospinal excitability, assessed with the amplitude of knee extensor motor evoked potentials, was also unchanged (p>0.05), as was the level of intracortical inhibition assessed with paired pulse TMS (short-interval intracortical inhibition, SICI). Time to task failure (~300 s) was not different (p>0.05) between the two sessions; accordingly, hypnosis did not influence neuromuscular adjustments measured during exercise and at task failure (p>0.05). Conclusion Hypnotic suggestions did not alter neuromuscular properties of the knee extensor muscles under resting condition or during/after exercise, suggesting that hypnosis-induced improvement in exercise performance and enhanced corticospinal excitability might be limited to highly susceptible participants. PMID:29684047

Delayed recovery of the affected finger extensors at chronic stage in a stroke patient: A case report.

PubMed

Jang, Sung Ho; Lee, Han Do

2017-10-01

A 33-year-old male presented with complete weakness of the right extremities due to corona radiata infarct. The main concerns of the patient is recovery of hand function especially related to finger extension. Right corona radiata infarct. He underwent physical therapy and occupational therapy at the outpatient clinic of the rehabilitation department of the same university hospital until 2 years after onset. In addition, he underwent neuromuscular electrical stimulation for the right finger extensors continuously until 4 years after onset. At 6 months after onset, the weakness of his right side recovered to subnormal state except for the right finger extensors which were completely weak. At 1.5 years after onset, the right finger extensors began to show slow and continuous recovery. At 4 years after onset, the patient showed motor recovery in the right finger extensors to the extent that he was able to move against gravity. Discontinuation of the left corticospinal tract was observed on 2-month diffusion tensor tractography (DTT); however, the integrity of this discontinuation had recovered to the primary motor cortex on 4-year DTT. On 2-month transcranial magnetic stimulation (TMS), no motor-evoked potential was evoked; in contrast, motor-evoked potentials were obtained at the right-hand muscle on 4-year TMS study. We demonstrated unusual delayed and long-term recovery of the affected finger extensors in a patient with corona radiata infarct using DTT and TMS.

Neuromuscular adaptations associated with knee joint angle-specific force change.

PubMed

Noorkõiv, Marika; Nosaka, Kazunori; Blazevich, Anthony J

2014-08-01

Neuromuscular adaptations to joint angle-specific force increases after isometric training have not yet been fully elucidated. This study examined angle-specific neuromuscular adaptations in response to isometric knee extension training at short (SL, joint angle 38.1° ± 3.7°) versus long (LL, 87.5° ± 6.0°) muscle lengths. Sixteen men trained three times a week for 6 wk either at SL (n = 8) or LL (n = 8). Voluntary maximal isometric knee extensor (MVC) force, doublet twitch force, EMG amplitudes (EMG/Mmax), and voluntary activation during MVC force (VA%) were measured at eight knee joint angles (30°-100°) at weeks 0, 3, and 6. Muscle volume and cross-sectional area (CSA) were measured from magnetic resonance imaging scans, and fascicle length (Lf) was assessed using ultrasonography before and after training. Clear joint angle specificity of force increase was seen in SL but not in LL. The 13.4% ± 9.7% (P = 0.01) force increase around the training angle in SL was related to changes in vastus lateralis and vastus medialis EMG/Mmax around the training angle (r = 0.84-0.88, P < 0.05), without changes in the doublet twitch force-angle relation or muscle size. In LL, muscle volume and CSA increased and the changes in CSA at specific muscle regions were correlated with changes in MVC force. A 5.4% ± 4.9% (P = 0.001) increase in Lf found in both groups was not associated with angle-specific force changes. There were no angle-specific changes in VA%. The EMG/Mmax, although not VA%, results suggest that neural adaptations underpinned training-related changes at short quadriceps lengths, but hypertrophic changes predominated after training at long lengths. The findings of this study should contribute to the development of more effective and evidence-based rehabilitation and strength training protocols.

Adaptive strength gains in dystrophic muscle exposed to repeated bouts of eccentric contraction

PubMed Central

Call, Jarrod A.; Eckhoff, Michael D.; Baltgalvis, Kristen A.; Warren, Gordon L.

2011-01-01

The objective of this study was to determine the functional recovery and adaptation of dystrophic muscle to multiple bouts of contraction-induced injury. Because lengthening (i.e., eccentric) contractions are extremely injurious for dystrophic muscle, it was considered that repeated bouts of such contractions would exacerbate the disease phenotype in mdx mice. Anterior crural muscles (tibialis anterior and extensor digitorum longus) and posterior crural muscles (gastrocnemius, soleus, and plantaris) from mdx mice performed one or five repeated bouts of 100 electrically stimulated eccentric contractions in vivo, and each bout was separated by 10–18 days. Functional recovery from one bout was achieved 7 days after injury, which was in contrast to a group of wild-type mice, which still showed a 25% decrement in electrically stimulated isometric torque at that time point. Across bouts there was no difference in the immediate loss of strength after repeated bouts of eccentric contractions for mdx mice (−70%, P = 0.68). However, after recovery from each bout, dystrophic muscle had greater torque-generating capacity such that isometric torque was increased ∼38% for both anterior and posterior crural muscles at bout 5 compared with bout 1 (P < 0.001). Moreover, isolated extensor digitorum longus muscles excised from in vivo-tested hindlimbs 14–18 days after bout 5 had greater specific force than contralateral control muscles (12.2 vs. 10.4 N/cm2, P = 0.005) and a 20% greater maximal relaxation rate (P = 0.049). Additional adaptations due to the multiple bouts of eccentric contractions included rapid recovery and/or sparing of contractile proteins, enhanced parvalbumin expression, and a decrease in fiber size variability. In conclusion, eccentric contractions are injurious to dystrophic skeletal muscle; however, the muscle recovers function rapidly and adapts to repeated bouts of eccentric contractions by improving strength. PMID:21960659

Lumbar extensor muscle force control is associated with disability in people with chronic low back pain.

PubMed

Pranata, Adrian; Perraton, Luke; El-Ansary, Doa; Clark, Ross; Fortin, Karine; Dettmann, Tim; Brandham, Robert; Bryant, Adam

2017-07-01

The ability to control lumbar extensor force output is necessary for daily activities. However, it is unknown whether this ability is impaired in chronic low back pain patients. Similarly, it is unknown whether lumbar extensor force control is related to the disability levels of chronic low back pain patients. Thirty-three chronic low back pain and 20 healthy people performed lumbar extension force-matching task where they increased and decreased their force output to match a variable target force within 20%-50% maximal voluntary isometric contraction. Force control was quantified as the root-mean-square-error between participants' force output and target force across the entire, during the increasing and decreasing portions of the force curve. Within- and between-group differences in force-matching error and the relationship between back pain group's force-matching results and their Oswestry Disability Index scores were assessed using ANCOVA and linear regression respectively. Back pain group demonstrated more overall force-matching error (mean difference=1.60 [0.78, 2.43], P<0.01) and more force-matching error while increasing force output (mean difference=2.19 [1.01, 3.37], P<0.01) than control group. The back pain group demonstrated more force-matching error while increasing than decreasing force output (mean difference=1.74, P<0.001, 95%CI [0.87, 2.61]). A unit increase in force-matching error while decreasing force output is associated with a 47% increase in Oswestry score in back pain group (R 2 =0.19, P=0.006). Lumbar extensor muscle force control is compromised in chronic low back pain patients. Force-matching error predicts disability, confirming the validity of our force control protocol for chronic low back pain patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Muscle group specific changes in the electromechanical delay following short-term resistance training.

PubMed

Stock, Matt S; Olinghouse, Kendra D; Mota, Jacob A; Drusch, Alexander S; Thompson, Brennan J

2016-09-01

The time delay between the onset of a muscle's electrical activity and force is believed to have important functional implications, and has been shown to decrease following resistance training in males. The purpose of this investigation was to examine changes in the voluntary electromechanical delay (EMD) for the leg extensors and flexors following a short-term resistance training intervention in females. Pretest/posttest control group experiment. Twenty-two previously untrained females (mean±SD age=21±2 years; mass=65.4±13.3kg) were randomly assigned to training (n=10) and control (n=12) groups. The training group performed barbell back squats and deadlifts twice per week for four weeks. EMD for the vastus lateralis (extensors) and biceps femoris (flexors) was examined during maximal voluntary contractions at pre- and posttesting. Data were examined using analyses of covariance (ANCOVAs) with the pretest and posttest scores serving as the covariate and dependent variable, respectively, and by evaluating the number of participants that exceeded the minimal difference statistic. For the leg extensors, the adjusted EMD posttest mean for the training group was significantly lower than that for the control group (74.3 vs. 91.8ms; p=0.015; ή(2)=0.275), and five training participants displayed decreases that exceeded the minimal difference. The ANCOVA for the leg flexors was not significant (adjusted means=98.0 vs. 90.0ms; p=0.487; ή(2)=.026). Four weeks of multi-joint resistance training resulted in decreased EMD for the leg extensors, but not the flexors. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. 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.

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.

Proprioceptive guidance of human voluntary wrist movements studied using muscle vibration.

PubMed Central

Cody, F W; Schwartz, M P; Smit, G P

1990-01-01

1. The alterations in voluntary wrist extension and flexion movement trajectories induced by application of vibration to the tendon of flexor carpi radialis throughout the course of the movement, together with the associated EMG patterns, have been studied in normal human subjects. Both extension and flexion movements were routinely of a target amplitude of 30 deg and made against a torque load of 0.32 N m. Flexor tendon vibration consistently produced undershooting of voluntary extension movements. In contrast, voluntary flexion movements were relatively unaffected. 2. The degree of vibration-induced undershooting of 1 s voluntary extension movements was graded according to the amplitude (0.75, 1.0 and 1.5 mm) of flexor tendon vibration. 3. As flexor vibration was initiated progressively later (at greater angular thresholds) during the course of 1 s voluntary extension movements, and the period of vibration was proportionately reduced, so the degree of vibration-induced undershooting showed a corresponding decline. 4. Varying the torque loads (0.32, 0.65 and 0.97 N m) against which 1 s extension movements were made, and thereby the strength of voluntary extensor contraction, produced no systematic changes in the degree of flexor vibration-induced undershooting. 5. Analysis of EMG patterns recorded from wrist flexor and extensor muscles indicated that vibration-induced undershooting of extension movements resulted largely from a reduction in activity in the prime-mover rather than increased antagonist activity. The earliest reductions in extensor EMG commenced some 40 ms after the onset of vibration, i.e. well before voluntary reaction time; these initial responses were considered to be 'automatic' in nature. 6. These results support the view that the central nervous system utilizes proprioceptive information in the continuous regulation of moderately slow voluntary wrist movements. Proprioceptive sensory input from the passively lengthening antagonist muscle, presumably arising mainly from muscle spindle I a afferents, appears to be particularly important and to act mainly in the reciprocal control of the prime-mover. PMID:2213604

ISOKINETIC KNEE MUSCLE STRENGTH PROFILE IN BRAZILIAN MALE SOCCER, FUTSAL, AND BEACH SOCCER PLAYERS: A CROSS-SECTIONAL STUDY

PubMed Central

Mascarin, Naryana C.; Vargas, Valentine Z.; Vancini, Rodrigo L.; Andrade, Marília S.

2017-01-01

Background Anterior cruciate ligament injury is higher in soccer athletes as compared to athletes of other sports. Risk factors for anterior cruciate ligament injury include low knee hamstring/quadriceps strength ratio and bilateral strength deficits. Purpose To investigate isokinetic thigh muscles strength, hamstring/quadriceps strength ratio, and bilateral strength comparisons in athletes who participate in professional soccer, futsal, and beach soccer. Study Design Cross-sectional study. Methods Brazilian professional soccer (n=70), futsal (n=30), and beach soccer (n=12) players were isokinetically assessed to examine strength of knee extensors and flexors at 60 degrees/second in concentric mode, to measure peak torque of dominant and non-dominant limbs. Results In the dominant limb, for extensors muscles, futsal players presented significantly lower peak torque values (223.9 ± 33.4 Nm) than soccer (250.9 ± 43.0 Nm; p=0.02) and beach soccer players (253.1 ± 32.4 Nm; p=0.03). Peak torque for extensor muscles in the non-dominant limb was significantly lower in futsal (224.0 ± 35.8 Nm) than in beach soccer players (256.8 ± 39.8 Nm; p=0.03). Hamstring/quadriceps strength ratio for dominant limbs for futsal (57.6 ± 10.1%), soccer (53.5 ± 8.8%), and beach soccer (56.3 ± 8.4%) players presented no significant differences between groups; however, the mean values were lower than recommended values found in the literature. There were no strength deficits for any of the evaluated groups when compared bilaterally. Conclusions Futsal athletes presented lower values for quadriceps strength than soccer and beach soccer athletes. Futsal, soccer, and beach soccer players presented no strength asymmetries, but they presented with strength imbalance in hamstring/quadriceps strength ratio. Level of Evidence 3 PMID:29234562

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.

Muscle protein and glycogen responses to recovery from hypogravity and unloading by tail-cast suspension

NASA Technical Reports Server (NTRS)

Henriksen, E. J.; Tischler, M. E.; Jacob, S.; Cook, P. H.

1985-01-01

Previous studies in this laboratory using the tail-bast hindlimb suspension model have shown that there are specific changes in protein and carbohydrate metabolism in the soleus muscle due to unloading. For example, 6 days of unloading caused a 27% decrease in mass and a 60% increase in glycogen content in the soleus muscle, while the extensor digitorum longus muscle was unaffected. Also, fresh tissue tyrosine and its in vitro release from the muscle are increased in the unloaded soleus, indicating that this condition causes a more negative protein balance. With these results in mind, studies to investigate the effect of hypogravity on protein and carbohydrate metabolism in a number of rat hindlimb muscles were carried out.

Muscle protein and glycogen responses to recovery from hypogravity and unloading by tail-cast suspension

NASA Technical Reports Server (NTRS)

Henriksen, E. J.; Tischler, M. E.; Jacob, S.; Cook, P. H.

1985-01-01

Previous studies in this laboratory using the tail-bast hindlimb suspension model have shown that there are specific changes in protein and carbohydrate metabolism in the soleus muscle due to unloading. For example, 6 days of unloading caused a 27 percent decrease in mass and a 60 percent increse in glycogen content in the soleus muscle, while the extensor digitorum longus muscle was unaffected. Also, fresh tissue tyrosine and its in vitro release from the muscle are increased in the unloaded soleus, indicating that this condition causes a more negative protein balance. With these results in mind, studies to investigate the effect of hypogravity on protein and carbohydrate metabolism in a number of rat hindlimb muscles were carried out.

Infant stepping: a method to study the sensory control of human walking

PubMed Central

Yang, Jaynie F; Stephens, Marilee J; Vishram, Rosie

1998-01-01

Stepping responses were studied in infants between the ages of 10 days and 10 months while they were supported to step on a slowly moving treadmill belt. Surface electromyography (EMG) from muscles in the lower limb, force exerted by the feet on the treadmill belt, and the motion of the lower limbs were recorded. Two groups of infants were studied, those who had a small amount of daily practice in stepping and those who did not. Practice resulted in a dramatic increase in the incidence of stepping recorded in the laboratory, particularly for the periods between 1 and 6 months of age. The majority of infants showed clear alternation between the flexor and extensor muscles during walking, regardless of age. Co-contraction between flexors and extensors, estimated by the overlap in area between rectified and smoothed EMG from a muscle pair, was greater for some muscle groups in the infant compared with the adult. Practice resulted in a significantly lower co-contraction index for the tibialis anterior- quadriceps muscle pair. Practice did not affect the mean step cycle duration. Infants of all ages could step at a range of treadmill speeds by adjusting their step cycle duration. The relationship between the treadmill speed and cycle duration was well fitted by a power function, similar to those reported for intact cats and adult humans. The change in step cycle duration resulted almost entirely from a change in the extensor burst duration, whereas the flexor burst duration remained constant. Airstepping could be elicited in some infants. The cycle durations for airstepping were close to the shortest cycles recorded on the treadmill. In conclusion, the system for generating rhythmic, alternating activity of the lower limbs for stepping is clearly developed by birth. The stepping is sustained and regular, particularly if stepping practice is incorporated briefly each day. The infant population provides a good subject pool for studying the afferent control of walking in the human, before cerebral influences are fully developed. The characteristics and maturity of the system remain to be determined. PMID:9508851

Effects of stretching and disuse on amino acids in muscles of rat hind limbs

NASA Technical Reports Server (NTRS)

Jaspers, Stephen R.; Henriksen, Erik J.; Satarug, Soisungwan; Tischler, Marc E.

1989-01-01

The effects of disuse and passive stretch on the concentrations of amino acids and ammonia in the unloaded soleus muscle was investigated in hindquarter-suspended (for six days by casting one foot in dorsiflexion) tail-casted rats. For a comparison with the condition of unloading, amino acids and ammonia were also measured in shortened extensor digitorum longus in the same casted limb and in denervated leg muscles. The results obtained suggest that passive stretch diminishes some of the characteristic alterations of amino acid concentrations due to unloading. This effect of stretch is considered to be due to the maintenance of muscle tension.

[Rupture of the tendon of the tibialis anterior muscle : Etiology, clinical symptoms and treatment].

PubMed

Waizy, H; Bouillon, B; Stukenborg-Colsman, C; Yao, D; Ettinger, S; Claassen, L; Plaass, C; Danniilidis, K; Arbab, D

2017-12-01

Ruptures of the tendon of the tibialis anterior muscle tend to occur in the context of degenerative impairments. This mainly affects the distal avascular portion of the tendon. Owing to the good compensation through the extensor hallucis longus and extensor digitorum muscles, diagnosis is often delayed. In addition to the clinical examination, magnetic resonance inaging (MRI) diagnostics are of particular importance, although damage or rupture of the tendon can also be demonstrated sonographically. Therapeutic measures include conservative or operative measures, depending on the clinical symptoms. Conservative stabilization of the ankle can be achieved by avoiding plantar flexion using a peroneal orthosis or an ankle-foot orthosis. Subsequent problems, such as metatarsalgia or overloading of the medial foot edge can be addressed by insoles or a corresponding shoe adjustment. An operative procedure is indicated when there is corresponding suffering due to pressure and functional impairment. The direct end-to-end reconstruction of the tendon is only rarely possible in cases of delayed diagnosis due to the degenerative situation and the retraction of the tendon stumps. Depending on the defect size and the tendon quality, various operative techniques, such as rotationplasty, free transplants or tendon transfer can be used.

A pilot study of contralateral homonymous muscle activity simulated electrical stimulation in chronic hemiplegia.

PubMed

Osu, Rieko; Otaka, Yohei; Ushiba, Junichi; Sakata, Sachiko; Yamaguchi, Tomofumi; Fujiwara, Toshiyuki; Kondo, Kunitsugu; Liu, Meigen

2012-01-01

For the recovery of hemiparetic hand function, a therapy was developed called contralateral homonymous muscle activity stimulated electrical stimulation (CHASE), which combines electrical stimulation and bilateral movements, and its feasibility was studied in three chronic stroke patients with severe hand hemiparesis. Patients with a subcortical lesion were asked to extend their wrist and fingers bilaterally while an electromyogram (EMG) was recorded from the extensor carpi radialis (ECR) muscle in the unaffected hand. Electric stimulation was applied to the homonymous wrist and finger extensors of the affected side. The intensity of the electrical stimulation was computed based on the EMG and scaled so that the movements of the paretic hand looked similar to those of the unaffected side. The patients received 30-minutes of therapy per day for 2 weeks. Improvement in the active range of motion of wrist extension was observed for all patients. There was a decrease in the scores of modified Ashworth scale in the flexors. Fugl-Meyer assessment scores of motor function of the upper extremities improved in two of the patients. The results suggest a positive outcome can be obtained using the CHASE system for upper extremity rehabilitation of patients with severe hemiplegia.

New method for determining total calcium content in tissue applied to skeletal muscle with and without calsequestrin

PubMed Central

Lamboley, Cédric R.H.; Kake Guena, Sandrine A.; Touré, Fatou; Hébert, Camille; Yaddaden, Louiza; Nadeau, Stephanie; Bouchard, Patrice; Wei-LaPierre, Lan; Lainé, Jean; Rousseau, Eric C.; Frenette, Jérôme; Protasi, Feliciano; Dirksen, Robert T.

2015-01-01

We describe a new method for determining the concentration of total Ca in whole skeletal muscle samples ([CaT]WM in units of mmoles/kg wet weight) using the Ca-dependent UV absorbance spectra of the Ca chelator BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid). Muscle tissue was homogenized in a solution containing 0.15 mM BAPTA and 0.5% sodium dodecyl sulfate (to permeabilize membranes and denature proteins) and then centrifuged. The solution volume was adjusted so that BAPTA captured essentially all of the Ca. [CaT]WM was obtained with Beer’s law from the absorbance change produced by adding 1 mM EGTA to capture Ca from BAPTA. Results from mouse, rat, and frog muscles were reasonably consistent with results obtained using other methods for estimating total [Ca] in whole muscles and in single muscle fibers. Results with external Ca removed before determining [CaT]WM indicate that most of the Ca was intracellular, indicative of a lack of bound Ca in the extracellular space. In both fast-twitch (extensor digitorum longus, EDL) and slow-twitch (soleus) muscles from mice, [CaT]WM increased approximately linearly with decreasing muscle weight, increasing approximately twofold with a twofold decrease in muscle weight. This suggests that the Ca concentration of smaller muscles might be increased relative to that in larger muscles, thereby increasing the specific force to compensate for the smaller mass. Knocking out the high capacity Ca-binding protein calsequestrin (CSQ) did not significantly reduce [CaT]WM in mouse EDL or soleus muscle. However, in EDL muscles lacking CSQ, muscle weights were significantly lower than in wild-type (WT) muscles and the values of [CaT]WM were, on average, about half the expected WT values, taking into account the above [CaT]WM versus muscle weight relationship. Because greater reductions in [CaT]WM would be predicted in both muscle types, we hypothesize that there is a substantial increase in Ca bound to other sites in the CSQ knockout muscles. PMID:25624449

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.

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.

Limb position sense, proprioceptive drift and muscle thixotropy at the human elbow joint

PubMed Central

Tsay, A; Savage, G; Allen, T J; Proske, U

2014-01-01

These experiments on the human forearm are based on the hypothesis that drift in the perceived position of a limb over time can be explained by receptor adaptation. Limb position sense was measured in 39 blindfolded subjects using a forearm-matching task. A property of muscle, its thixotropy, a contraction history-dependent passive stiffness, was exploited to place muscle receptors of elbow muscles in a defined state. After the arm had been held flexed and elbow flexors contracted, we observed time-dependent changes in the perceived position of the reference arm by an average of 2.8° in the direction of elbow flexion over 30 s (Experiment 1). The direction of the drift reversed after the arm had been extended and elbow extensors contracted, with a mean shift of 3.5° over 30 s in the direction of elbow extension (Experiment 2). The time-dependent changes could be abolished by conditioning elbow flexors and extensors in the reference arm at the test angle, although this led to large position errors during matching (±10°), depending on how the indicator arm had been conditioned (Experiments 3 and 4). When slack was introduced in the elbow muscles of both arms, by shortening muscles after the conditioning contraction, matching errors became small and there was no drift in position sense (Experiments 5 and 6). These experiments argue for a receptor-based mechanism for proprioceptive drift and suggest that to align the two forearms, the brain monitors the difference between the afferent signals from the two arms. PMID:24665096

Position sense at the human forearm in the horizontal plane during loading and vibration of elbow muscles

PubMed Central

Ansems, G E; Allen, T J; Proske, U

2006-01-01

When blindfolded subjects match the position of their forearms in the vertical plane they rely on signals coming from the periphery as well as from the central motor command. The command signal provides a positional cue from the accompanying effort sensation required to hold the arm against gravity. Here we have asked, does a centrally generated effort signal contribute to position sense in the horizontal plane, where gravity cannot play a role? Blindfolded subjects were required to match forearm position for the unloaded arm and when flexors or extensors were bearing 10%, 25% or 40% of maximum loads. Before each match the reference arm was conditioned by contracting elbow muscles while the arm was held flexed or extended. For the unloaded arm conditioning led to a consistent pattern of errors which was attributed to signals from flexor and extensor muscle spindles. When elbow muscles were loaded the errors from conditioning converged, presumably because the spindles had become coactivated through the fusimotor system during the load-bearing contraction. However, this convergence was seen only when subjects supported a static load. When they moved the load differences in errors from conditioning persisted. Muscle vibration during load bearing or moving a load did not alter the distribution of errors. It is concluded that for position sense of an unloaded arm in the horizontal plane the brain relies on signals from muscle spindles. When the arm is loaded, an additional signal of central origin contributes, but only if the load is moved. PMID:16873408

Maintenance of skeletal muscle energy homeostasis during prolonged wintertime fasting in the raccoon dog (Nyctereutes procyonoides).

PubMed

Kinnunen, Sanni; Mänttäri, Satu; Herzig, Karl-Heinz; Nieminen, Petteri; Mustonen, Anne-Mari; Saarela, Seppo

2015-05-01

The raccoon dog (Nyctereutes procyonoides) is a canid species with autumnal fattening and prolonged wintertime fasting. Nonpathological body weight cycling and the ability to tolerate food deficiency make this species a unique subject for studying physiological mechanisms in energy metabolism. AMP-activated protein kinase (AMPK) is a cellular energy sensor regulating energy homeostasis. During acute fasting, AMPK promotes fatty acid oxidation and enhances glucose uptake. We evaluated the effects of prolonged fasting on muscle energy metabolism in farm-bred raccoon dogs. Total and phosphorylated AMPK and acetyl-CoA carboxylase (ACC), glucose transporter 4 (GLUT 4), insulin receptor and protein kinase B (Akt) protein expressions of hind limb muscles were determined by Western blot after 10 weeks of fasting. Plasma insulin, leptin, ghrelin, glucose and free fatty acid levels were measured, and muscle myosin heavy chain (MHC) isoform composition analyzed. Fasting had no effects on AMPK phosphorylation, but total AMPK expression decreased in m. rectus femoris, m. tibialis anterior and m. extensor digitorum longus resulting in a higher phosphorylation ratio. Decreased total expression was also observed for ACC. Fasting did not influence GLUT 4, insulin receptor or Akt expression, but Akt phosphorylation was lower in m. flexor digitorum superficialis and m. extensor digitorum longus. Three MHC isoforms (I, IIa and IIx) were detected without differences in composition between the fasted and control animals. The studied muscles were resistant to prolonged fasting indicating that raccoon dogs have an effective molecular regulatory system for preserving skeletal muscle function during wintertime immobility and fasting.

Procedure Oriented Torsional Anatomy of the Forearm for Spasticity Injection.

PubMed

Chiou-Tan, Faye; Cianca, John; John, Joslyn; Furr-Stimming, Erin; Pandit, Sindhu; Taber, Katherine H

2015-01-01

: This is the second in a series of articles related to the concept of "torsional" anatomy. The objective of this article is to provide musculoskeletal ultrasound (MSKUS) anatomy of the forearm in the position of hemispastic flexion as a reference relevant to needle procedures. The MSKUS images were obtained in a healthy human subject. Marker dots were placed over common injection sites in the forearm for spasticity. The MSKUS probe was centered over each dot to obtain a cross-sectional view. A pair of MSKUS images was recorded for each site: the first in anatomic neutral and second in hemiparetic spastic position. The images were compared side to side. In addition, a video recording was made at each site to track the movement of the muscles and nerves during internal rotation. The pronator teres (PT) rotated medially and the brachialis and biceps tendon rotated in view. In addition, the median nerve became more superficial. The flexor carpi radialis rotated medially and was replaced by PT and the median nerve. The flexor carpi ulnaris and flexor digitorum profundus rotated medially and were replaced by the flexor carpi radialis, PT and median nerve. The flexor digitorum superficialis was replaced by the brachioradialis, extensor carpi radialis brevis, and radial nerve. The brachioradialis was replaced by the extensor carpi radialis brevis and extensor digitorum communis. Intended muscle targets rotate out of view and injection range. These are replaced by other muscles and nerves that could inadvertently be injected. This potentially could result in both increased complications and decreased efficacy of the procedure. It is hoped that this series of images will increase the accuracy and safety of needle placement for spasticity injections in the forearm.

The effects of low and moderate doses of caffeine supplementation on upper and lower body maximal voluntary concentric and eccentric muscle force.

PubMed

Tallis, Jason; Yavuz, Harley C M

2018-03-01

Despite the growing quantity of literature exploring the effect of caffeine on muscular strength, there is a dearth of data that directly explores differences in erogenicity between upper and lower body musculature and the dose-response effect. The present study sought to investigate the effects of low and moderate doses of caffeine on the maximal voluntary strength of the elbow flexors and knee extensors. Ten nonspecifically strength-trained, recreationally active participants (aged 21 ± 0.3 years) completed the study. Using a randomised, counterbalanced, and double-blind approach, isokinetic concentric and eccentric strength was measured at 60 and 180°/s following administration of a placebo, 3 mg·kg -1 body mass caffeine, and 6 mg·kg -1 body mass caffeine. There was no effect of caffeine on the maximal voluntary concentric and eccentric strength of the elbow flexors, or the eccentric strength of the knee extensors. Both 3 and 6 mg·kg -1 body mass caffeine caused a significant increase in peak concentric force of the knee extensors at 180°/s. No difference was apparent between the 2 concentrations. Only 6 mg·kg -1 body mass caused an increase in peak concentric force during repeated contractions. The results infer that the effective caffeine concentration to evoke improved muscle performance may be related to muscle mass and contraction type. The present work indicates that a relatively low dose of caffeine treatment may be effective for improving lower body muscular strength, but may have little benefit for the strength of major muscular groups of the upper body.

Effects of combined electromyostimulation and gymnastics training in prepubertal girls.

PubMed

Deley, Gaëlle; Cometti, Carole; Fatnassi, Anaïs; Paizis, Christos; Babault, Nicolas

2011-02-01

This study investigated the effects of a 6-week combined electromyostimulation (EMS) and gymnastic training program on muscle strength and vertical jump performance of prepubertal gymnasts. Sixteen young women gymnasts (age 12.4 ± 1.2 yrs) participated in this study, with 8 in the EMS group and the remaining 8 as controls. EMS was conducted on knee extensor muscles for 20 minutes 3 times a week during the first 3 weeks and once a week during the last 3 weeks. Gymnasts from both groups underwent similar gymnastics training 5-6 times a week. Isokinetic torque of the knee extensors was determined at different eccentric and concentric angular velocities ranging from -60 to +240° per second. Jumping ability was evaluated using squat jump (SJ), counter movement jump (CMJ), reactivity test, and 3 gymnastic-specific jumps. After the first 3 weeks of EMS, maximal voluntary torque was increased (+40.0 ± 10.0%, +35.3 ± 11.8%, and +50.6 ± 7.7% for -60, +60, and +240°s⁻¹, respectively; p < 0.05), as well as SJ, reactivity test and specific jump performances (+20.9 ± 8.3%, +20.4 ± 26.2% and +14.9 ± 17.2% respectively; p < 0.05). Six weeks of EMS were necessary to improve the CMJ (+10.1 ± 10.0%, p < 0.05). Improvements in jump ability were still maintained 1 month after the end of the EMS training program. To conclude, these results first demonstrate that in prepubertal gymnasts, a 6-week EMS program, combined with the daily gymnastic training, induced significant increases both in knee extensor muscle strength and nonspecific and some specific jump performances.

Trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise.

PubMed

Farrokhi, Shawn; Pollard, Christine D; Souza, Richard B; Chen, Yu-Jen; Reischl, Stephen; Powers, Christopher M

2008-07-01

Experimental laboratory study. To examine how a change in trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. Altering the position of the trunk during the forward lunge exercise is thought to affect the muscular actions of the lead lower extremity. However, no studies have compared the biomechanical differences between the traditional forward lunge and its variations. Ten healthy adults (5 males, 5 females; mean age +/- SD, 26.7 +/- 3.2 years) participated. Lower extremity kinematics, kinetics, and surface electromyographic (EMG) data were obtained while subjects performed 3 lunge exercises: normal lunge with the trunk erect (NL), lunge with the trunk forward (LTF), and lunge with trunk extension (LTE). A 1-way analysis of variance with repeated measures was used to compare lower extremity kinematics, joint impulse (area under the moment-time curve), and normalized EMG (highest 1-second window of activity for selected lower extremity muscles) among the 3 lunge conditions. During the LTF condition, significant increases were noted in peak hip flexion angle, hip extensor and ankle plantar flexor impulse, as well as gluteus maximus and biceps femoris EMG (P<.015) when compared to the NL condition. During the LTE condition, a significant increase was noted in peak ankle dorsiflexion and a significant decrease was noted in peak hip flexion angle (P<.015) compared to the NL condition. Performing a lunge with the trunk forward increased the hip extensor impulse and the recruitment of the hip extensors. In contrast, performing a forward lunge with the trunk extended did not alter joint impulse or activation of the lower extremity musculature. Therapy, level 5.

Relationship between mechanical factors and incidence of low back pain.

PubMed

Nourbakhsh, Mohammad Reza; Arab, Amir Massoud

2002-09-01

A multifactorial cross-sectional nonexperimental design. To collectively investigate the association among 17 mechanical factors and occurrence of low back pain (LBP). Several physical characteristics, based on assumptions, clinical findings, and scientific experiments, have been associated with the development of LBP Controversy exists regarding the degree of association between some of these physical characteristics and LBP. Information regarding the degree of association of each factor to LBP is needed for effective prevention and appropriate treatment strategies. A total of 600 subjects participated in this study. Subjects were categorized into 4 groups: asymptomatic men (n = 150, age [mean +/- SD] = 43 +/- 15 years), asymptomatic women (n = 150, age [mean +/- SD] = 43 +/- 13 years), men with LBP (n = 150, age [mean +/- SD] = 43 +/- 14 years), and women with LBP (n = 150, age [mean +/- SD] = 43 +/- 13 years). Seventeen physical characteristics were measured in each group and the relative association of each characteristic with LBP was assessed. Among all the factors tested, endurance of the back extensor muscles had the highest association with LBP Other factors such as the length of the back extensor muscles, and the strength of the hip flexor, hip adductor, and abdominal muscles also had a significant association with LBP. It appears that muscle endurance and weakness are associated with LBP and that structural factors such as the size of the lumbar lordosis, pelvic tilt, leg length discrepancy, and the length of abdominal, hamstring, and iliopsoas muscles are not associated with the occurrence of LBP.

Eccentric knee flexor torque following anterior cruciate ligament surgery.

PubMed

Osternig, L R; James, C R; Bercades, D T

1996-10-01

The purposes of this study were to compare eccentric knee flexor torque and muscle activation in the limbs of normal (NOR) subjects and in subjects who had undergone unilateral ACI, autograft surgical reconstruction (INJ) and to assess the effect of movement speed on EMG/ torque ratios and eccentric-concentric actions. Fourteen subjects (7 NOR and 7 INJ) were tested for knee eccentric flexor torque and EMG activity at four isokinetic speeds (15 degrees, 30 degrees, 45 degrees and 60 degrees.s-1). Results revealed that post-surgical limbs (ACL) produced significantly less (P < 0.05) eccentric torque and flexor EMG activity at 60 degrees.s-1 than uninjured (UNI) contralateral limbs. Eccentric torque rose significantly as speed increased from 45 degrees to 60 degrees.s-1 for surgical group uninjured limbs and NOR group left and right limbs. Eccentric flexor torque increased with speed for both groups and approximated equality with concentric extensor torque at 60 degrees.s-1 for INJ group ACL and UNI limbs. Concentric flexor muscle EMG/torque ratios were 30-191% greater than eccentric muscle actions across groups and speeds. The results suggest that ACL dysfunction may result in reduced eccentric flexor torque at rapid movement speeds, that eccentric flexor torque increases with movement speed and may have the capacity to counter forceful extensor concentric torque, and that eccentric muscle actions produce less muscle activation per unit force than concentric actions which may reflect reduced energy cost.

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

Near infrared spectroscopy of human muscles

NASA Astrophysics Data System (ADS)

Gasbarrone, R.; Currà, A.; Cardillo, A.; Bonifazi, G.; Serranti, S.

2018-02-01

Optical spectroscopy is a powerful tool in research and industrial applications. Its properties of being rapid, non-invasive and not destructive make it a promising technique for qualitative as well as quantitative analysis in medicine. Recent advances in materials and fabrication techniques provided portable, performant, sensing spectrometers readily operated by user-friendly cabled or wireless systems. We used such a system to test whether infrared spectroscopy techniques, currently utilized in many areas as primary/secondary raw materials sector, cultural heritage, agricultural/food industry, environmental remote and proximal sensing, pharmaceutical industry, etc., could be applied in living humans to categorize muscles. We acquired muscles infrared spectra in the Vis-SWIR regions (350-2500 nm), utilizing an ASD FieldSpec 4 Standard-Res Spectroradiometer with a spectral sampling capability of 1.4 nm at 350-1000 nm and 1.1 nm at 1001-2500 nm. After a preliminary spectra pre-processing (i.e. signal scattering reduction), Principal Component Analysis (PCA) was applied to identify similar spectral features presence and to realize their further grouping. Partial Least-Squares Discriminant Analysis (PLS-DA) was utilized to implement discrimination/prediction models. We studied 22 healthy subjects (age 25-89 years, 11 females), by acquiring Vis-SWIR spectra from the upper limb muscles (i.e. biceps, a forearm flexor, and triceps, a forearm extensor). Spectroscopy was performed in fixed limb postures (elbow angle approximately 90‡). We found that optical spectroscopy can be applied to study human tissues in vivo. Vis-SWIR spectra acquired from the arm detect muscles, distinguish flexors from extensors.

Alterations in cervical muscle activity in functional and stressful tasks in female office workers with neck pain.

PubMed

Johnston, V; Jull, G; Darnell, R; Jimmieson, N L; Souvlis, T

2008-06-01

This study determined differences between computer workers with varying levels of neck pain in terms of work stressors, employee strain, electromyography (EMG) amplitude and heart rate response to various tasks. Participants included 85 workers (33, no pain; 38, mild pain; 14, moderate pain) and 22 non-working controls. Work stressors evaluated were job demands, decision authority, and social support. Heart rate was recorded during three tasks: copy-typing, typing with superimposed stress and a colour word task. Measures included electromyography signals from the sternocleidomastoid (SCM), anterior scalene (AS), cervical extensor (CE) and upper trapezius (UT) muscles bilaterally. Results showed no difference between groups in work stressors or employee strain measures. Workers with and without pain had higher measured levels of EMG amplitude in SCM, AS and CE muscles during the tasks than controls (all P < 0.02). In workers with neck pain, the UT had difficulty in switching off on completion of tasks compared with controls and workers without pain. There was an increase in heart rate, perceived tension and pain and decrease in accuracy for all groups during the stressful tasks with symptomatic workers producing more typing errors than controls and workers without pain. These findings suggest an altered muscle recruitment pattern in the neck flexor and extensor muscles. Whether this is a consequence or source of the musculoskeletal disorder cannot be determined from this study. It is possible that workers currently without symptoms may be at risk of developing a musculoskeletal disorder.

Effects of subacute pyridostigmine administration on mammalian skeletal muscle function. (Reannouncement with new availability information)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adler, M.; Deshpande, S.S.; Foster, R.E.

1992-12-31

The subacute effects of pyridostigmine bromide were investigated on the contractile properties of rat extensor digitorum longus (EDL) and diaphragm muscles. The cholinesterase inhibitor was delivered via subcutaneously implanted osmotic minipumps (Alzet) at 9 microns g h-1 (low dose) or 60 micro g h-1 (high dose). Animals receiving high-dose pyridostigmine pumps exhibited marked alterations in muscle properties within the first day of exposure that persisted for the remaining 13 days. With 0.1 Hz stimulation, EDL twitch tensions of treated animals were elevated relative to control. Repetitive stimulation at frequencies > 1 Hz led a use-dependent depression in the amplitude ofmore » successive twitches during the train. Recovery from pyridostigmine was essentially complete by 1 day of withdrawal. Rats implanted with low-dose pyridostigmine pumps showed little or no alteration of in vivo twitch tensions during the entire 14 days of treatment. Diaphragm and EDL muscles excised from pyridostigmine-treated rats and tested in vitro showed no significant alterations in twitch and tetanic tensions and displayed the same sensitivity as muscles of control animals to subsequent pyridostigmine exposures. In the presence of atropine, subacutely administered pyridostigmine protected rats from two LD5O doses of the irreversible cholinesterase inhibitor, soman. In the absence of atropine, the LD50 of soman was not altered by subacute pyridostigmine treatment. Extensor digitorum longus; diaphragm; twitch tension; ACh release; subacute; Alzet pumps; tolerance; anticholinesterase; pyridostigmine; soman.« less

Electrical and Mechanical Responses in Deep Abdominal Extensor Muscles of Crayfish and Lobster

PubMed Central

Abbott, Bernard C.; Parnas, I.

1965-01-01

Electrical and mechanical studies have been made of the deep abdominal extensor muscles, medial (DEAM) and lateral (DEAL), of crayfish and lobster. The medial muscle responds to direct (intracellular) and indirect stimulation with a transient membrane depolarization which exhibits the properties of a propagated non-decremental action potential but does not overshoot the zero level. The amplitude is about 30 mv in crayfish and 50 mv in lobster. It is followed by a fast all-or-none twitch whose duration at 20°C is 30 to 50 msec. and whose developed tension is 500 gm/cm2 or about half the tetanic value. Membrane potential is K+-dependent and immersion in high K+ induces a brief transient tension rise as in other twitch-type muscles. The action potential and twitch are normal even if all external Na+ is replaced with sucrose but vary with external Ca++, the action potential increasing 8 to 10 mv for a twofold increase in Ca++. The lateral muscle (DEAL) is much slower and responds to intracellular stimulation only with an electrotonic or a local response. Mechanical responses and relaxation speeds are slow with minimal duration of contraction of 0.5 to 2 seconds. Immersion in high K solutions induces large maintained tensions. Sarcomere length in the fast DEAM is uniform and about 2 µ at rest, but in the DEAL speed is less and sarcomere length is greater averaging about 4.5 µ but with a mixed population of fibers. PMID:14324996

Decreased neck muscle strength in patients with the loss of cervical lordosis.

PubMed

Alpayci, Mahmut; Şenköy, Emre; Delen, Veysel; Şah, Volkan; Yazmalar, Levent; Erden, Metin; Toprak, Murat; Kaplan, Şeyhmus

2016-03-01

The loss of cervical lordosis is associated with some negative clinical outcomes. No previous study has examined cervical muscle strength, specifically in patients with the loss of cervical lordosis. This study aims to investigate whether there is weakness of the cervical muscles or an imbalance between cervical flexor and extensor muscle strength in patients with the loss of cervical lordosis compared with healthy controls matched by age, gender, body mass index (BMI), and employment status. Thirty-two patients with the loss of cervical lordosis (23 F, 9 M) and 31 healthy volunteers (23 F, 8 M) were included in the study. Maximal isometric neck extension and flexion strength, and the strength ratio between extension and flexion were used as evaluation parameters. All measurements were conducted by a blinded assessor using a digital force gauge. The participants were positioned on a chair in a neutral cervical position and without the trunk inclined during measurements. Maximal isometric neck extension and flexion strength values were significantly lower in the patients versus healthy controls (P<0.001 and P=0.040, respectively). The mean (SD) values of the extension/flexion ratio were 1.21 (0.34) in the patients and 1.46 ± 0.33 in the controls (P=0.004). According to our results, patients with the loss of cervical lordosis have reduced neck muscle strength, especially in the extensors. These findings may be beneficial for optimizing cervical exercise prescriptions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Muscular responses appear to be associated with existence of kinesthetic perception during combination of tendon co-vibration and motor imagery.

PubMed

Shibata, Eriko; Kaneko, Fuminari; Katayose, Masaki

2017-11-01

The afferent inputs from peripheral sensory receptors and efferent signals from the central nervous system that underlie intentional movement can contribute to kinesthetic perception. Previous studies have revealed that tendon vibration to wrist muscles elicits an excitatory response-known as the antagonist vibratory response-in muscles antagonistic to the vibrated muscles. Therefore, the present study aimed to further investigate the effect of tendon vibration combined with motor imagery on kinesthetic perception and muscular activation. Two vibrators were applied to the tendons of the left flexor carpi radialis and extensor carpi radialis. When the vibration frequency was the same between flexors and extensors, no participant perceived movement and no muscle activity was induced. When participants imagined flexing their wrists during tendon vibration, the velocity of perceptual flexion movement increased. Furthermore, muscle activity of the flexor increased only during motor imagery. These results demonstrate that kinesthetic perception can be induced during the combination of motor imagery and co-vibration, even with no experience of kinesthetic perception from an afferent input with co-vibration at the same frequency. Although motor responses were observed during combined co-vibration and motor imagery, no such motor responses were recorded during either co-vibration alone or motor imagery alone, suggesting that muscular responses during the combined condition are associated with kinesthetic perception. Thus, the present findings indicate that kinesthetic perception is influenced by the interaction between afferent input from muscle spindles and the efferent signals that underlie intentional movement. We propose that the physiological behavior resulting from kinesthetic perception affects the process of modifying agonist muscle activity, which will be investigated in a future study.

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.

17-(allylamino)-17-demethoxygeldanamycin drives Hsp70 expression but fails to improve morphological or functional recovery in injured skeletal muscle.

PubMed

Baumann, Cory W; Otis, Jeffrey S

2015-12-01

The stress inducible 70 kDa heat shock protein (Hsp70) is instrumental to efficient morphological and functional recovery following skeletal muscle injury because of its roles in protein quality control and molecular signalling. Therefore, in attempt to improve recovery, Hsp70 expression was increased with 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) prior to and following an intramuscular injection of barium chloride (BaCl2) into the tibialis anterior (TA) of healthy young mice. To assess recovery, regenerating fibre cross-sectional area (CSA) of the TA and in vivo peak isometric torque produced by the anterior crural muscles (TA, extensor digitorum longus and extensor hallucis muscles) were analyzed for up to 3 weeks after the injury. Because treatment of 17-AAG and Hsp70 are known to influence inflammatory and myogenic signalling, tumor necrosis factor-α (TNF-α) and myogenin content were also assessed. This study reports that 17-AAG was effective at up-regulating Hsp70 expression, increasing content fivefold in the uninjured muscle. However, this significant increase in Hsp70 content did not enhance morphological or functional recovery following the injury, as the return of regenerating fibre CSA and in vivo peak isometric torque did not differ compared to that of the injured muscle from the vehicle treated mice. Treatment with 17-AAG also altered TNF-α and myogenin content, increasing both to a greater extent after the injury. Together, these findings demonstrate that although 17-AAG may alter molecular makers of regeneration, it does not improve recovery following BaCl2-induced skeletal muscle injury in healthy young mice. © 2015 Wiley Publishing Asia Pty Ltd.

Presynaptic control of transmission along the pathway mediating disynaptic reciprocal inhibition in the cat

PubMed Central

Enríquez-Denton, M; Nielsen, J; Perreault, M-C; Morita, H; Petersen, N; Hultborn, H

2000-01-01

In cat lumbar motoneurones, disynaptic inhibitory postsynaptic potentials (IPSPs) evoked by stimulation of antagonist motor nerves were depressed for at least 150 ms following conditioning stimulation of flexor (1.7-2 times threshold (T)) and ankle extensor (5T) nerves. The aim of the present study was to investigate the possibility that this depression is caused by presynaptic inhibitory mechanisms acting at the terminals of group I afferent fibres projecting to the Ia inhibitory interneurones and/or the terminals of these interneurones to the target motoneurones. Conditioning stimulation of flexor, but not ankle extensor, nerves evoked a depression of the monosynaptic Ia excitatory postsynaptic potentials (EPSPs) recorded intracellularly in Ia inhibitory interneurones. This depression lasted between 200 and 700 ms and was not accompanied by a depression of the monosynaptic EPSPs evoked by stimulation of descending pathways. These results suggest that flexor, but not ankle extensor, group I afferent fibres can modulate sensory transmission at the synapse between Ia afferent fibres and Ia inhibitory interneurones. Conditioning stimulation of flexor muscle nerves, extensor muscle nerves and cutaneous nerves produced a long-lasting increase in excitability of the terminals of the Ia inhibitory interneurones. The increase in the excitability of the terminals was not secondary to an electrotonic spread of synaptic excitation at the soma. Indeed, concomitant with the excitability increase of the terminals there were signs of synaptic inhibition in the soma. The unitary IPSPs induced in target motoneurones following the spike activity of single Ia inhibitory interneurones were depressed by conditioning stimulation of muscle and cutaneous nerves. Since the conditioning stimulation also evoked compound IPSPs in those motoneurones, a firm conclusion as to whether unitary IPSP depression involved presynaptic inhibitory mechanism of the terminals of the interneurones could not be reached. The possibility that the changes in excitability of the Ia interneuronal terminals reflect the presence of a presynaptic inhibitory mechanism similar to that operating at the terminals of the afferent fibres (presynaptic inhibition) is discussed.1. In cat lumbar motoneurones, disynaptic inhibitory postsynaptic potentials (IPSPs) evoked by stimulation of antagonist motor nerves were depressed for at least 150 ms following conditioning stimulation of flexor (1.7-2 times threshold (T)) and ankle extensor (5T) nerves. The aim of the present study was to investigate the possibility that this depression is caused by presynaptic inhibitory mechanisms acting at the terminals of group I afferent fibres projecting to the Ia inhibitory interneurones and/or the terminals of these interneurones to the target motoneurones. PMID:10922013

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.

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.

Anatomy of the pectoral and forelimb muscles of wildtype and green fluorescent protein-transgenic axolotls and comparison with other tetrapods including humans: a basis for regenerative, evolutionary and developmental studies

PubMed Central

Diogo, R; Tanaka, E M

2012-01-01

The axolotl Ambystoma mexicanum is one of the most used model organisms in evolutionary, developmental and regenerative studies, particularly because it can reconstitute a fully functional and complete forelimb/hindlimb. Surprisingly, there is no publication that describes all the pectoral and forelimb muscles of this species or provides a comparative framework between these muscles and those of other model organisms and of modern humans. In the present paper we describe and illustrate all these muscles in A. mexicanum and provide the first report about the myology of adults of a model organism that is based on analyses and dissections of both wildtype animals and transgenic animals that express green fluorescent protein (GFP) in muscle fibers. On the one hand, the inclusion of GFP-transgenic animals allows us to show the muscles as more commonly seen, and thus easier to understand, by current developmental and regenerative biologists. On the other hand, by including wildtype and GFP-transgenic animals and by visualizing these latter animals with and without a simultaneous transmission laser light, we were able to obtain a more complete and clearer understanding of the exact limit of the fleshy and tendinous parts of the muscles and their specific connections with the skeletal elements. This in turn allowed us to settle some controversies in previous anatomical and comparative studies. As most developmental, regenerative and evolutionary biologists are interested in comparing their observations of A. mexicanum with observations in other model organisms, and ultimately in using this information to increase the understanding of human evolution and medicine, we also provide tables showing the homologies between the pectoral and forelimb muscles of axolotls, of model organisms such as mice, frogs and chicken, and of Homo sapiens. An example illustrating the outcomes of using our methodology and of our observations is that they revealed that, contrary to what is often stated in the literature, A. mexicanum has a muscle coracoradialis that has both a well developed proximal fleshy belly and a distal long and thin tendon, supporting the idea that this muscle very likely corresponds to at least part of the amniote biceps brachii. Our observations also: (i) confirmed that the flexores digitorum minimi, interphalangeus digiti 3, pronator quadratus and palmaris profundus 1 are present as distinct muscles in A. mexicanum, supporting the idea that the latter muscle does not correspond to the pronator accessorius of reptiles; (ii) confirmed that the so-called extensor antebrachii radialis is present as a distinct muscle in this species and, importantly, indicated that this muscle corresponds to the supinator of other tetrapods; (iii) showed that, contrary to some other urodeles, including some other Ambystoma species, there is no distinct muscle epitrochleoanconeus in A. mexicanum and; (iv) showed that the ulnar and radial bundles of the abductor et extensor digiti 1 correspond to the abductor pollicis longus and extensor pollicis longus of other tetrapods, respectively. PMID:22957800

Anatomy of the pectoral and forelimb muscles of wildtype and green fluorescent protein-transgenic axolotls and comparison with other tetrapods including humans: a basis for regenerative, evolutionary and developmental studies.

PubMed

Diogo, R; Tanaka, E M

2012-12-01

The axolotl Ambystoma mexicanum is one of the most used model organisms in evolutionary, developmental and regenerative studies, particularly because it can reconstitute a fully functional and complete forelimb/hindlimb. Surprisingly, there is no publication that describes all the pectoral and forelimb muscles of this species or provides a comparative framework between these muscles and those of other model organisms and of modern humans. In the present paper we describe and illustrate all these muscles in A. mexicanum and provide the first report about the myology of adults of a model organism that is based on analyses and dissections of both wildtype animals and transgenic animals that express green fluorescent protein (GFP) in muscle fibers. On the one hand, the inclusion of GFP-transgenic animals allows us to show the muscles as more commonly seen, and thus easier to understand, by current developmental and regenerative biologists. On the other hand, by including wildtype and GFP-transgenic animals and by visualizing these latter animals with and without a simultaneous transmission laser light, we were able to obtain a more complete and clearer understanding of the exact limit of the fleshy and tendinous parts of the muscles and their specific connections with the skeletal elements. This in turn allowed us to settle some controversies in previous anatomical and comparative studies. As most developmental, regenerative and evolutionary biologists are interested in comparing their observations of A. mexicanum with observations in other model organisms, and ultimately in using this information to increase the understanding of human evolution and medicine, we also provide tables showing the homologies between the pectoral and forelimb muscles of axolotls, of model organisms such as mice, frogs and chicken, and of Homo sapiens. An example illustrating the outcomes of using our methodology and of our observations is that they revealed that, contrary to what is often stated in the literature, A. mexicanum has a muscle coracoradialis that has both a well developed proximal fleshy belly and a distal long and thin tendon, supporting the idea that this muscle very likely corresponds to at least part of the amniote biceps brachii. Our observations also: (i) confirmed that the flexores digitorum minimi, interphalangeus digiti 3, pronator quadratus and palmaris profundus 1 are present as distinct muscles in A. mexicanum, supporting the idea that the latter muscle does not correspond to the pronator accessorius of reptiles; (ii) confirmed that the so-called extensor antebrachii radialis is present as a distinct muscle in this species and, importantly, indicated that this muscle corresponds to the supinator of other tetrapods; (iii) showed that, contrary to some other urodeles, including some other Ambystoma species, there is no distinct muscle epitrochleoanconeus in A. mexicanum and; (iv) showed that the ulnar and radial bundles of the abductor et extensor digiti 1 correspond to the abductor pollicis longus and extensor pollicis longus of other tetrapods, respectively. © 2012 The Authors. Journal of Anatomy © 2012 Anatomical Society.

Reliability and Validity of a New Method for Isometric Back Extensor Strength Evaluation Using A Hand-Held Dynamometer

PubMed Central

2017-01-01

Objective To investigate the reliability and validity of a new method for isometric back extensor strength measurement using a portable dynamometer. Methods A chair equipped with a small portable dynamometer was designed (Power Track II Commander Muscle Tester). A total of 15 men (mean age, 34.8±7.5 years) and 15 women (mean age, 33.1±5.5 years) with no current back problems or previous history of back surgery were recruited. Subjects were asked to push the back of the chair while seated, and their isometric back extensor strength was measured by the portable dynamometer. Test-retest reliability was assessed with intraclass correlation coefficient (ICC). For the validity assessment, isometric back extensor strength of all subjects was measured by a widely used physical performance evaluation instrument, BTE PrimusRS system. The limit of agreement (LoA) from the Bland-Altman plot was evaluated between two methods. Results The test-retest reliability was excellent (ICC=0.82; 95% confidence interval, 0.65–0.91). The Bland-Altman plots demonstrated acceptable agreement between the two methods: the lower 95% LoA was −63.1 N and the upper 95% LoA was 61.1 N. Conclusion This study shows that isometric back extensor strength measurement using a portable dynamometer has good reliability and validity. PMID:29201818

Spatial Orientation in Flight

DTIC Science & Technology

1986-12-01

on posture, exerted through tonic activation of so-called " antigravity " muscles such as hip and knee extensors. These vestibular reflexes, of course... antigravity houses, which are built in such a way that the visually apparent vertical is quite different from the true 112 %IN.. Figure 43. Conditioned

Kinesiology Review 1971.

ERIC Educational Resources Information Center

American Association for Health, Physical Education, and Recreation, Washington, DC.

This report contains articles on research in kinesiology, the study of the principles of mechanics and anatomy in relation to human movement. Research on sequential timing, somatotype methodology, and linear measurement with cinematographical analysis are presented in the first section. Studies of the hip extensor muscles, kinetic energy, and…

Fetal damage after accidental polio vaccination of an immune mother

PubMed Central

Burton, A. E.; Robinson, E. T.; Harper, W. F.; Bell, E. J.; Boyd, J. F.

1984-01-01

Irreparable damage to the anterior horn cells of the cervical and thoracic cord was found in a 20-week-old fetus whose mother was immune to poliomyelitis before conceiving but who was inadvertently given oral polio vaccine at 18 weeks gestation. Polio neutralizing antibody titres in sera, taken before and after pregnancy, were identical and were at levels normally regarded as providing protection. Unsuccessful attempts were made to isolate poliovirus from extracts of fetal brain, lung, liver and placenta. Fluorescent antibody tests were performed on various levels of the central nervous system and on the left and right extensor forearm muscles. Specific positive fluorescence to poliovirus 2 and 3 antigens was detected at dorsal spinal cord level only. One positive result was seen with Coxsackie A9 antiserum and fresh guinea-pig complement in the inflammatory cells in the right extensor forearm muscles. This experience, as yet unexplained, underlines the importance of ensuring that women are not pregnant prior to oral polio vaccination. ImagesFigure 1.Figure 2. PMID:6747944

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.

A pilot study to determine whether differences exist in histochemical properties between the trapezius and extensor carpi radialis brevis muscles in women with work-related myalgia.

PubMed

Green, Howard J; Ranney, Don; Burnett, Margaret; Galvin, Patti; Kyle, Natasha; Iqbal, Sobia; Lounsbury, David; Ouyang, Jing; Smith, Ian C; Stewart, Riley; Tick, Heather; Tupling, A Russell

2014-04-01

To investigate fibre-type abnormalities in women with work-related myalgia (WRM), tissue samples were extracted from their trapezius (TRAP) and the extensor carpi radialis brevis (ECRB) muscles and compared with healthy controls (CON). For the ECRB samples (CON, n = 6; WRM, n = 11), no differences (P > 0.05) were found between groups for any of the properties examined, namely fibre-type (I, IIA, IIX, IIAX) distribution, cross-sectional fibre area, capillary counts (CC), capillary to fibre area ratio, and succinic dehydrogenase activity. For the TRAP samples (CON, n = 6; WRM, n = 8), the only difference (P < 0.05) observed between groups was for CC (CON > WRM), which was not statistically significant (P > 0.05) when age was used a covariant. A comparison of the properties of these 2 muscles in the CON group indicated a higher (P < 0.05) and lower (P < 0.05) percentage of type I and type IIA fibres, respectively, in the TRAP as well as higher (P < 0.05) CC, which was not specific to fibre type. These preliminary results suggest that the properties employed to characterize fibre types do not differentiate CON from WRM for either the TRAP or ECRB. As a consequence, the role of inherent fibre-type differences between these muscles in the pathogenesis of WRM remains uncertain.

Velocity associated characteristics of force production in college weight lifters

PubMed Central

Kanehisa, H.; Fukunaga, T.

1999-01-01

OBJECTIVE: To determine velocity specific isokinetic forces and cross sectional areas of reciprocal muscle groups in Olympic weight lifters. METHODS: The cross sectional area of the flexor or extensor muscles of the elbow or knee joint was determined by a B-mode ultrasonic apparatus in 34 college weight lifters and 31 untrained male subjects matched for age. Maximum voluntary force produced in the flexion and extension of the elbow and knee joints was measured on an isokinetic dynamometer at 60, 180, and 300 degrees/s. RESULTS: The average cross sectional area was 31-65% higher, and the force was 19-62% higher in weight lifters than in the untrained subjects. The ratio of force to cross sectional area was the same in both groups. The weight lifters showed a lower velocity associated decline in force than untrained subjects in the elbow and knee flexors but not in the extensors. CONCLUSIONS: These results indicate that for muscle contractions with velocities between 60 degrees/s and 300 degrees/s the difference in isokinetic force between weight lifters and untrained subjects can be primarily attributed to the difference in the muscle cross sectional area. However, the lower velocity associated decline in force implies that weight lifters may have a higher force per cross sectional area than untrained subjects at velocities above 300 degrees/s. 




 PMID:10205693

The First Experience of Triple Nerve Transfer in Proximal Radial Nerve Palsy.

PubMed

Emamhadi, Mohammadreza; Andalib, Sasan

2018-01-01

Injury to distal portion of posterior cord of brachial plexus leads to palsy of radial and axillary nerves. Symptoms are usually motor deficits of the deltoid muscle; triceps brachii muscle; and extensor muscles of the wrist, thumb, and fingers. Tendon transfers, nerve grafts, and nerve transfers are options for surgical treatment of proximal radial nerve palsy to restore some motor functions. Tendon transfer is painful, requires a long immobilization, and decreases donor muscle strength; nevertheless, nerve transfer produces promising outcomes. We present a patient with proximal radial nerve palsy following a blunt injury undergoing triple nerve transfer. The patient was involved in a motorcycle accident with complete palsy of the radial and axillary nerves. After 6 months, on admission, he showed spontaneous recovery of axillary nerve palsy, but radial nerve palsy remained. We performed triple nerve transfer, fascicle of ulnar nerve to long head of the triceps branch of radial nerve, flexor digitorum superficialis branch of median nerve to extensor carpi radialis brevis branch of radial nerve, and flexor carpi radialis branch of median nerve to posterior interosseous nerve, for restoration of elbow, wrist, and finger extensions, respectively. Our experience confirmed functional elbow, wrist, and finger extensions in the patient. Triple nerve transfer restores functions of the upper limb in patients with debilitating radial nerve palsy after blunt injuries. Copyright © 2017 Elsevier Inc. All rights reserved.

Modulation of the cytosolic androgen receptor in striated muscle by sex steroids

NASA Technical Reports Server (NTRS)

Rance, N. E.; Max, S. E.

1982-01-01

The influence of orchiectomy (GDX) and steroid administration on the level of the cytosolic androgen receptor in the rat levator ani muscle and in rat skeletal muscles (tibialis anterior and extensor digitorum longus) was studied. Androgen receptor binding to muscle cytosol was measured using H-3 methyltrienolone (R1881) as ligand, 100 fold molar excess unlabeled R1881 to assess nonspecific binding, and 500 fold molar excess of triamcinolone acetonide to prevent binding to glucocorticoid and progestin receptors. Results demonstrate that modification of the levels of sex steroids can alter the content of androgen receptors of rat striated muscle. Data suggest that: (1) cytosolic androgen receptor levels increase after orchiectomy in both levator ani muscle and skeletal muscle; (2) the acute increase in receptor levels is blocked by an inhibitor of protein synthesis; and (3) administration of estradiol-17 beta to castrated animals increases receptor binding in levator ani muscle but not in skeletal muscle.

Distal muscle involvement in granulomatous myositis can mimic inclusion body myositis.

PubMed

Larue, Sandrine; Maisonobe, Thierry; Benveniste, Olivier; Chapelon-Abric, Catherine; Lidove, Olivier; Papo, Thomas; Eymard, Bruno; Dubourg, Odile

2011-06-01

The authors report on four patients aged over 50 with chronic myopathy suggestive of sporadic inclusion body myositis. They present progressive and selective weakness of the quadriceps femoris muscles. Asymmetrical and selective atrophy of the forearm muscles were noted in all, with more severe involvement of the flexors than the extensors. Biopsy revealed granulomatous myositis. Histological features of sporadic inclusion body myositis were lacking. Evidence for systemic sarcoidosis was found in one patient. Corticosteroid treatment was associated with a partial but significant improvement in two patients. Granulomatous myositis may mimic inclusion body myositis and may be steroid-responsive.

Skeletal muscle response to spaceflight, whole body suspension, and recovery in rats

NASA Technical Reports Server (NTRS)

Musacchia, X. J.; Steffen, J. M.; Fell, R. D.; Dombrowski, M. J.

1990-01-01

The effects of a 7-day spaceflight (SF), 7- and 14-day-long whole body suspension (WBS), and 7-day-long recovery on the muscle weight and the morphology of the soleus and the extensor digitorum longus (EDL) of rats were investigated. It was found that the effect of 7-day-long SF and WBS were highly comparable for both the soleus and the EDL, although the soleus muscle from SF rats showed greater cross-sectional area reduction than that from WBS rats. With a longer duration of WBS, there was a continued reduction in cross-sectional fast-twitch fiber area. Muscle plasticity, in terms of fiber and capillary responses, showed differences in responses of the two types of muscles, indicating that antigravity posture muscles are highly susceptible to unloading.

Effect of inactivity and passive stretch on protein turnover in phasic and postural rat muscles

NASA Technical Reports Server (NTRS)

Loughna, P.; Goldspink, G.; Goldspink, D. F.

1986-01-01

Muscle atrophy in humans can occur during prolonged bed rest, plaster cast immobilization, and space flight. In the present study, the suspension model used by Musacchia et al. (1983) is employed to investigate changes in protein synthesis and degradation in fast-twitch phasic (extensor digitorum longus) and slow-twitch postural (soleus) muscles in the rat, following hypokinesia and hypodynamia. In addition, the use of passive stretch was examined as a means of preventing atrophy. The obtained results suggest that the mechanisms controlling the processes of protein synthesis and protein breakdown during muscle disuse atrophy may be independent of each other. It appears, however, that the muscle atrophy due to hypokinesia and hypodynamia can be temporarily prevented by passively stretching a muscle.

Contractile properties of rat fast-twitch skeletal muscle during reinnervation - Effects of testosterone and castration

NASA Technical Reports Server (NTRS)

Yeagle, S. P.; Mayer, R. F.; Max, S. R.

1983-01-01

The peroneal nerve of subject rats were crushed 1 cm from the muscle in order to examine the isometric contractile properties of skeletal muscle in the recovery sequency during reinnervation of normal, castrated, and testosterone-treated rats. The particular muscle studied was the extensor digitorum longus, with functional reinnervation first observed 8-9 days after nerve crush. No evidence was found that either castration or testosterone injections altered the process of reinnervation after the nerve crush, with the conclusion being valid at the 0.05 p level. The most reliable index of reinnervation was found to be the twitch:tetanus ratio, a factor of use in future studies of the reinnervation of skeletal muscle.

Differential effect of denervation on free radical scavenging enzymes in slow and fast muscle of rat

NASA Technical Reports Server (NTRS)

Asayama, K.; Dettbarn, W. D.; Burr, I. M.

1985-01-01

To determine the effect of denervation on the free radical scavenging systems in relation to the mitochondrial oxidative metabolism in the slow twitch soleus and fast twitch extensor digitorum longus (EDL) muscles, the sciatic nerve of the rat was crushed in the mid-thigh region and the muscle tissue levels of 5 enzymes were studied 2 and 5 weeks following crush. Radioimmunoassays were utilized for the selective measurement of cuprozinc (cytosolic) and mangano (mitochondrial) superoxide dismutases. These data represent the first systematic report of free radical scavening systems in slow and fast muscles in response to denervation. Selective modification of cuprozinc and manganosuperoxide dismutases and differential regulation of GSH-peroxidase was demonstrated in slow and fast muscle.

Functional anatomy of the cheetah (Acinonyx jubatus) forelimb.

PubMed

Hudson, Penny E; Corr, Sandra A; Payne-Davis, Rachel C; Clancy, Sinead N; Lane, Emily; Wilson, Alan M

2011-04-01

Despite the cheetah being the fastest living land mammal, we know remarkably little about how it attains such high top speeds (29 m s(-1)). Here we aim to describe and quantify the musculoskeletal anatomy of the cheetah forelimb and compare it to the racing greyhound, an animal of similar mass, but which can only attain a top speed of 17 m s(-1). Measurements were made of muscle mass, fascicle length and moment arms, enabling calculations of muscle volume, physiological cross-sectional area (PCSA), and estimates of joint torques and rotational velocities. Bone lengths, masses and mid-shaft cross-sectional areas were also measured. Several species differences were observed and have been discussed, such as the long fibred serratus ventralis muscle in the cheetah, which we theorise may translate the scapula along the rib cage (as has been observed in domestic cats), thereby increasing the cheetah's effective limb length. The cheetah's proximal limb contained many large PCSA muscles with long moment arms, suggesting that this limb is resisting large ground reaction force joint torques and therefore is not functioning as a simple strut. Its structure may also reflect a need for control and stabilisation during the high-speed manoeuvring in hunting. The large digital flexors and extensors observed in the cheetah forelimb may be used to dig the digits into the ground, aiding with traction when galloping and manoeuvring. © 2011 The Authors. Journal of Anatomy © 2011 Anatomical Society of Great Britain and Ireland.

Changes in muscle strength in individuals with statin-induced myopathy: A summary of 3 investigations.

PubMed

Panza, Gregory A; Taylor, Beth A; Dada, Marcin R; Thompson, Paul D

2015-01-01

There are inconsistent findings regarding muscular weakness in individuals with statin-induced myalgia. We used rigorous muscle testing to compare findings from 3 investigations in 3 different study populations to determine if statin myalgia is associated with measurable weakness. In all 3 studies, we measured maximal isometric handgrip strength, resting respiratory exchange ratio (RER), and knee extensor isometric and isokinetic force. In 2 of the 3 studies, elbow flexor isometric and isokinetic force and knee endurance fatigue index were also assessed. Knee extensor and elbow flexor measurements were obtained using an isokinetic dynamometer. Resting RER was measured using a metabolic breath-by-breath collection method. Measurement outcomes were compared on vs off drug. In study 1, 18 participants fit the criteria for statin myalgia. Participants taking atorvastatin 80 mg daily had significantly lower muscle strength in 5 (P < .05) of 14 measured variables. Participants on placebo (N = 10) with myalgia had significantly lower muscle strength in 4 (P < .05) of 14 measured variables. In study 2, 18 participants tested positive for statin-induced myalgia when receiving simvastatin 20 mg daily and displayed no significant muscle strength changes (all P > .05). In study 3, 11 patients with statin-induced myalgia completed the study and had a significant decrease in 2 (P < .05) of 10 leg muscle strength variables. In all 3 studies, no significant changes were shown for handgrip strength or RER (all P > .05). Our results indicate that after a short-term treatment with statin therapy, a rigorous muscle strength protocol does not show decrements of muscle strength in subjects with statin myalgia. Short-term treatment with statin therapy is not common in clinical practice. Thus, future studies should examine the effects of prolonged statin therapy on muscle strength. Published by Elsevier Inc.

Bradykinin type 2 receptor -9/-9 genotype is associated with triceps brachii muscle hypertrophy following strength training in young healthy men.

PubMed

Popadic Gacesa, Jelena Z; Momcilovic, Milica; Veselinovic, Igor; Brodie, David A; Grujic, Nikola G

2012-11-06

Bradykinin type 2 receptor (B2BRK) genotype was reported to be associated with changes in the left-ventricular mass as a response to aerobic training, as well as in the regulation of the skeletal muscle performance in both athletes and non-athletes. However, there are no reports on the effect of B2BRK 9-bp polymorphism on the response of the skeletal muscle to strength training, and our aim was to determine the relationship between the B2BRK SNP and triceps brachii functional and morphological adaptation to programmed physical activity in young adults. In this 6-week pretest-posttest exercise intervention study, twenty nine healthy young men (21.5 ± 2.7 y, BMI 24.2 ± 3.5 kg/m(2)) were put on a 6-week exercise protocol using an isoacceleration dynamometer (5 times a week, 5 daily sets with 10 maximal elbow extensions, 1 minute rest between sets). Triceps brachii muscle volumes were assessed by using magnetic resonance imaging before and after the strength training. Bradykinin type 2 receptor 9 base pair polymorphism was determined for all participants. Following the elbow extensors training, an average increase in the volume of both triceps brachii was 5.4 ± 3.4% (from 929.5 ± 146.8 cm(3) pre-training to 977.6 ± 140.9 cm(3) after training, p<0.001). Triceps brachii volume increase was significantly larger in individuals homozygous for -9 allele compared to individuals with one or two +9 alleles (-9/-9, 8.5 ± 3.8%; vs. -9/+9 and +9/+9 combined, 4.7 ± 4.5%, p < 0.05). Mean increases in endurance strength in response to training were 48.4 ± 20.2%, but the increases were not dependent on B2BRK genotype (-9/-9, 50.2 ± 19.2%; vs. -9/+9 and +9/+9 combined, 46.8 ± 20.7%, p > 0.05). We found that muscle morphological response to targeted training - hypertrophy - is related to polymorphisms of B2BRK. However, no significant influence of different B2BRK genotypes on functional muscle properties after strength training in young healthy non athletes was found. This finding could be relevant, not only in predicting individual muscle adaptation capacity to training or sarcopenia related to aging and inactivity, but also in determining new therapeutic strategies targeting genetic control of muscle function, especially for neuromuscular disorders that are characterized by progressive adverse changes in muscle quality, mass, strength and force production (e.g., muscular dystrophy, multiple sclerosis, Parkinson's disease).

Specific force of the vastus lateralis in adults with achondroplasia.

PubMed

Sims, David T; Onambélé-Pearson, Gladys L; Burden, Adrian; Payton, Carl; Morse, Christopher I

2018-03-01

Achondroplasia is a clinical condition defined by shorter stature and disproportionate limb length. Force production in able-bodied individuals (controls) is proportional to muscle size, but given the disproportionate nature of achondroplasia, normalizing to anatomical cross-sectional area (ACSA) is inappropriate. The aim of this study was to assess specific force of the vastus lateralis (VL) in 10 adults with achondroplasia (22 ± 3 yr) and 18 sex-matched controls (22 ± 2 yr). Isometric torque (iMVCτ) of the dominant knee extensors (KE) and in vivo measures of VL muscle architecture, volume, activation, and patella tendon moment arm were used to calculate VL physiological CSA (PCSA), fascicle force, and specific force in both groups. Achondroplasic muscle volume was 53% smaller than controls (284 ± 36 vs. 604 ± 102 cm 3 , P < 0.001). KE iMVCτ was 63% lower in achondroplasia compared with controls (95 ± 24 vs. 256 ± 47 N⋅m, P < 0.001). Activation and moment arm length were similar between groups ( P > 0.05), but coactivation of bicep femoris of achondroplasic subjects was 70% more than controls (43 ± 20 vs. 13 ± 5%, P < 0.001). Achondroplasic subjects had 58% less PCSA (43 ± 10 vs. 74.7 ± 14 cm 2 , P < 0.001), 29% lower fascicle force (702 ± 235 vs. 1704 ± 303 N, P < 0.001), and 29% lower specific force than control subjects (17 ± 6 vs. 24 ± 6 N⋅cm -2 , P = 0.012). The smaller VL specific force in achondroplasia may be attributed to infiltration of fat and connective tissue, rather than to any difference in myofilament function. NEW & NOTEWORTHY The novel observation of this study was the measurement of normalized force production in a group of individuals with disproportionate limb length-to-torso ratios.

Alterations of the in vivo torque-velocity relationship of human skeletal muscle following 30 days exposure to simulated microgravity

NASA Technical Reports Server (NTRS)

Dudley, Gary A.; Duvoisin, Marc; Convertino, Victor A.; Buchanan, Paul

1989-01-01

The effect of a continuous 30-d-long 6-deg headdown bedrest (BR) on the force output ability of skeletal muscles was investigated in human subjects by measuring peak angle specific torque of the knee extensor (KE) and knee flexor (KF) muscle groups of both limbs during unilateral efforts at four speeds (0.52. 1.74, 2.97, and 4.19 rad/sec) during eccentric action. It was found that, for the KE muscle group, the headdown BR resulted in decreases, by 19 percent on the average, of peak angle specific torque; on the other hand, the strength of the KF muscles was not altered significantly. A post-BR recovery for 30 days was found to restore muscle strength of the KE muscle group to about 92 percent of the pre-BR values. Changes of strength were not affected by the type of speed of muscle action.

Cross-talk in mechanomyographic signals from the forearm muscles during sub-maximal to maximal isometric grip force.

PubMed

Islam, Md Anamul; Sundaraj, Kenneth; Ahmad, R Badlishah; Sundaraj, Sebastian; Ahamed, Nizam Uddin; Ali, Md Asraf

2014-01-01

This study aimed: i) to examine the relationship between the magnitude of cross-talk in mechanomyographic (MMG) signals generated by the extensor digitorum (ED), extensor carpi ulnaris (ECU), and flexor carpi ulnaris (FCU) muscles with the sub-maximal to maximal isometric grip force, and with the anthropometric parameters of the forearm, and ii) to quantify the distribution of the cross-talk in the MMG signal to determine if it appears due to the signal component of intramuscular pressure waves produced by the muscle fibers geometrical changes or due to the limb tremor. Twenty, right-handed healthy men (mean ± SD: age  = 26.7±3.83 y; height  = 174.47±6.3 cm; mass  = 72.79±14.36 kg) performed isometric muscle actions in 20% increment from 20% to 100% of the maximum voluntary isometric contraction (MVIC). During each muscle action, MMG signals generated by each muscle were detected using three separate accelerometers. The peak cross-correlations were used to quantify the cross-talk between two muscles. The magnitude of cross-talk in the MMG signals among the muscle groups ranged from, R2(x, y) = 2.45-62.28%. Linear regression analysis showed that the magnitude of cross-talk increased linearly (r2 = 0.857-0.90) with the levels of grip force for all the muscle groups. The amount of cross-talk showed weak positive and negative correlations (r2 = 0.016-0.216) with the circumference and length of the forearm respectively, between the muscles at 100% MVIC. The cross-talk values significantly differed among the MMG signals due to: limb tremor (MMGTF), slow firing motor unit fibers (MMGSF) and fast firing motor unit fibers (MMGFF) between the muscles at 100% MVIC (p<0.05, η2 = 0.47-0.80). The results of this study may be used to improve our understanding of the mechanics of the forearm muscles during different levels of the grip force.

The histochemical profile of the rat extensor digitorum longus muscle differentiates after birth and dedifferentiates in senescence.

PubMed

Lehnert, M; Laurer, H; Maier, B; Frank, J; Marzi, I; Steudel, W-I; Mautes, A

2007-01-01

Age dependent motor unit dedifferentiation is a key component of impaired muscle function in advanced age. Here, we tested the hypothesis that rat muscle histochemical profile during the lifespan of an individual has an age-specific pattern since comprehensive longitudinal studies of muscle differentiation after birth and dedifferentiation in advanced age are scarce. Our results show that extensor digitorum longus muscle (EDL) is comprised only of two fiber types after birth, type slow-oxidative (SO) and type SDH-intermediate (SDH-INT), the latter being indicative for the presence of polyneuronal innervation. In contrast to the constantly growing cross-sectional area of the muscle fibers, a dramatic decrease in SDH-INT proportion occurs between day 14 and 21 after birth resulting in a complete loss of fiber type SDH-INT at the age of 90 days (p<0.05). At the age of 270 days, the fiber type composition of rat EDL dedifferentiates as shown by the reappearance of the SDH-INT type with a further increase at the age of 540 days (p<0.05). These changes in histochemical fiber type spectra are brought about by fiber type conversion within the fast twich fibers. The findings of the present study provide further evidence that fiber type conversion is a basic mechanism leading to motor unit differentiation and dedifferentiation during ontogenesis. Fiber type conversion shows a distinct time specific pattern and is also characteristic for motor unit regeneration after peripheral nerve repair. Factors that influence fiber type conversion and thereby motor unit organization may provide a future therapeutic option to enhance the regenerative capacity of motor units.

Tenotomy of m.soleus antagonists prevents the changes in fiber type characteristics and sarcomeric cytoskeletal proteins in unloaded rats

NASA Astrophysics Data System (ADS)

Moukhina, Alexandra; Ardabievskaya, Anna; Vikhlyantsev, Ivan; Podlubnaya, Zoya; Nemirovskaya, Tatiana; Shenkman, Boris

2005-08-01

It is known that activity of postural extensors (m. soleus) decreases and activity of flexors (m. tibialis anterior) increases under unloading conditions. We have tested the hypothesis supposing that increased flexor activities during unloading exert suppressive influence on postural extensor activities and thus lead to dramatic changes in fiber size, MHC expression, sarcomeric proteins content in m.soleus. We have inactivated hindlimb flexor muscles (m.soleus antagonists) by bilateral tenotomy. 20 male Wistar rats were divided on 3 groups: cage control (C), hindlimb suspension for 14 days (HS), tenotomy of hindlimb flexor muscles with 14 days hindlimb suspension afterwards (HST). Several soleus muscle fiber characteristics decreased significantly in HS group (p<0.05) as compared with C group: cross sectional area (CSA) of type I muscle fibers, titin/MyHC ratio and nebulin/MyHC ratio. MyHC isoform pattern shifted slow-to-fast significantly. NFATc1 content increased in nuclear protein extract of m. soleus in HS group. None of these parameters was significantly different in HST group from those of C group. It has been concluded that the tenotomy of flexors under hindlimb suspension prevents atrophy of type I muscle fibers, decrease the degradation of titin and nebulin and prevent slow-to-fast shift of fiber MyHC isoform pattern, possibly through prevention of increase NFATc1 content in muscle fiber nuclear protein extract. Therefore, suppressive influence of increased flexor activity could be one of mechanisms that lead to the changes in m. soleus under unloading conditions. The work was supported by RFBR grants: 02-04-50025, 03- 04-48487 and the special program of RAS "Integration mechanisms of functional control in the living system".

Gene Expression Profiling in Slow-Type Calf Soleus Muscle of 30 Days Space-Flown Mice.

PubMed

Gambara, Guido; Salanova, Michele; Ciciliot, Stefano; Furlan, Sandra; Gutsmann, Martina; Schiffl, Gudrun; Ungethuem, Ute; Volpe, Pompeo; Gunga, Hanns-Christian; Blottner, Dieter

2017-01-01

Microgravity exposure as well as chronic disuse are two main causes of skeletal muscle atrophy in animals and humans. The antigravity calf soleus is a reference postural muscle to investigate the mechanism of disuse-induced maladaptation and plasticity of human and rodent (rats or mice) skeletal musculature. Here, we report microgravity-induced global gene expression changes in space-flown mouse skeletal muscle and the identification of yet unknown disuse susceptible transcripts found in soleus (a mainly slow phenotype) but not in extensor digitorum longus (a mainly fast phenotype dorsiflexor as functional counterpart to soleus). Adult C57Bl/N6 male mice (n = 5) flew aboard a biosatellite for 30 days on orbit (BION-M1 mission, 2013), a sex and age-matched cohort were housed in standard vivarium cages (n = 5), or in a replicate flight habitat as ground control (n = 5). Next to disuse atrophy signs (reduced size and myofiber phenotype I to II type shift) as much as 680 differentially expressed genes were found in the space-flown soleus, and only 72 in extensor digitorum longus (only 24 genes in common) compared to ground controls. Altered expression of gene transcripts matched key biological processes (contractile machinery, calcium homeostasis, muscle development, cell metabolism, inflammatory and oxidative stress response). Some transcripts (Fzd9, Casq2, Kcnma1, Ppara, Myf6) were further validated by quantitative real-time PCR (qRT-PCR). Besides previous reports on other leg muscle types we put forth for the first time a complete set of microgravity susceptible gene transcripts in soleus of mice as promising new biomarkers or targets for optimization of physical countermeasures and rehabilitation protocols to overcome disuse atrophy conditions in different clinical settings, rehabilitation and spaceflight.

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.

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

Gene Expression Profiling in Slow-Type Calf Soleus Muscle of 30 Days Space-Flown Mice

PubMed Central

Gambara, Guido; Salanova, Michele; Ciciliot, Stefano; Furlan, Sandra; Gutsmann, Martina; Schiffl, Gudrun; Ungethuem, Ute; Volpe, Pompeo; Gunga, Hanns-Christian; Blottner, Dieter

2017-01-01

Microgravity exposure as well as chronic disuse are two main causes of skeletal muscle atrophy in animals and humans. The antigravity calf soleus is a reference postural muscle to investigate the mechanism of disuse-induced maladaptation and plasticity of human and rodent (rats or mice) skeletal musculature. Here, we report microgravity-induced global gene expression changes in space-flown mouse skeletal muscle and the identification of yet unknown disuse susceptible transcripts found in soleus (a mainly slow phenotype) but not in extensor digitorum longus (a mainly fast phenotype dorsiflexor as functional counterpart to soleus). Adult C57Bl/N6 male mice (n = 5) flew aboard a biosatellite for 30 days on orbit (BION-M1 mission, 2013), a sex and age-matched cohort were housed in standard vivarium cages (n = 5), or in a replicate flight habitat as ground control (n = 5). Next to disuse atrophy signs (reduced size and myofiber phenotype I to II type shift) as much as 680 differentially expressed genes were found in the space-flown soleus, and only 72 in extensor digitorum longus (only 24 genes in common) compared to ground controls. Altered expression of gene transcripts matched key biological processes (contractile machinery, calcium homeostasis, muscle development, cell metabolism, inflammatory and oxidative stress response). Some transcripts (Fzd9, Casq2, Kcnma1, Ppara, Myf6) were further validated by quantitative real-time PCR (qRT-PCR). Besides previous reports on other leg muscle types we put forth for the first time a complete set of microgravity susceptible gene transcripts in soleus of mice as promising new biomarkers or targets for optimization of physical countermeasures and rehabilitation protocols to overcome disuse atrophy conditions in different clinical settings, rehabilitation and spaceflight. PMID:28076365

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.

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.

Functional anatomy of the cheetah (Acinonyx jubatus) hindlimb

PubMed Central

Hudson, Penny E; Corr, Sandra A; Payne-Davis, Rachel C; Clancy, Sinead N; Lane, Emily; Wilson, Alan M

2011-01-01

The cheetah is capable of a top speed of 29 ms−1 compared to the maximum speed of 17 ms−1 achieved by the racing greyhound. In this study of the hindlimb and in the accompanying paper on the forelimb we have quantified the musculoskeletal anatomy of the cheetah and greyhound and compared them to identify any differences that may account for this variation in their locomotor abilities. Specifically, bone length, mass and mid-shaft diameter were measured, along with muscle mass, fascicle lengths, pennation angles and moment arms to enable estimates of maximal isometric force, joint torques and joint rotational velocities to be calculated. Surprisingly the cheetahs had a smaller volume of hip extensor musculature than the greyhounds, and we therefore propose that the cheetah powers acceleration using its extensive back musculature. The cheetahs also had an extremely powerful psoas muscle which could help to resist the pitching moments around the hip associated with fast accelerations. The hindlimb bones were proportionally longer and heavier, enabling the cheetah to take longer strides and potentially resist higher peak limb forces. The cheetah therefore possesses several unique adaptations for high-speed locomotion and fast accelerations, when compared to the racing greyhound. PMID:21062282

How are tonic and phasic cardiovascular changes related to central motor command?

PubMed

Jennings, J R; van der Molen, M W; Brock, K; Somsen, R J

1993-07-01

We examined the influence of central motor command on heart rate, respiration, and peripheral vascular activity. Central command was enhanced or reduced using tendon vibration. Muscle tension was held constant permitting the examination of variation in central command. Experiment 1 demonstrated in 13 college-aged males an enhancement of heart rate and vascular responses to an isometric, extensor contraction when vibration of the flexor tendon was added. Experiment 2 asked whether changes in central command interacted with phasic cardiovascular changes such as stimulus-linked anticipatory cardiac deceleration. Twenty college-aged males performed either an isometric flexor or extensor contraction with or without flexor tendon vibration. As expected, vibration enhanced cardiovascular change with extensor contraction more than with flexor contraction. Relative to control contractions, however, the flexor change was not an absolute decrease in cardiovascular change. More importantly, tendon vibration failed to alter phasic cardiovascular changes. Force and central commands for force induce cardiovascular change, but this change seems independent of phasic changes induced by the anticipation and processing of environmental stimuli.

Partially irreversible paresis of the deep peroneal nerve caused by osteocartilaginous exostosis of the fibula without affecting the tibialis anterior muscle.

PubMed

Paprottka, Felix Julian; Machens, Hans-Günther; Lohmeyer, Jörn Andreas

2012-08-01

Dysfunction of the lower limb's muscles can cause severe impairment and immobilisation of the patient. As one of the leg's major motor and sensory nerves, the deep peroneal nerve (synonym: deep fibular nerve) plays a very important role in muscle innervation in the lower extremities. We report the case of a 19-year-old female patient, who suffered from a brace-like exostosis 6-cm underneath her left fibular head causing a partially irreversible paresis of her deep peroneal nerve. This nerve damage resulted in complete atrophy of her extensor digitorum longus and extensor hallucis longus muscle, and in painful sensory disturbance at her left shin and first web space. The tibialis anterior muscle stayed intact because its motor branch left the deep peroneal nerve proximal to the nerve lesion. Diagnosis was first verified 6 years after the onset of symptoms by a magnetic resonance imaging (MRI) scan of her complete left lower leg. Subsequently, the patient was operated on in our clinic, where a neurolysis was performed and the 4-cm-long osteocartilaginous exostosis was removed. Paralysis was already irreversible but sensibility returned completely after neurolysis. The presented case shows that an osteocartilaginous exostosis can be the cause for partial deep peroneal nerve paresis. If this disorder is diagnosed at an early stage, nerve damage is reversible. Typical for an exostosis is its first appearance during the juvenile growth phase. Copyright © 2012 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Short-Term Motor Compensations to Denervation of Feline Soleus and Lateral Gastrocnemius Result in Preservation of Ankle Mechanical Output during Locomotion

PubMed Central

Prilutsky, Boris I.; Maas, Huub; Bulgakova, Margarita; Hodson-Tole, Emma F.; Gregor, Robert J.

2011-01-01

Denervation of selected ankle extensors in animals results in locomotor changes. These changes have been suggested to permit preservation of global kinematic characteristics of the hindlimb during stance. The peak ankle joint moment is also preserved immediately after denervation of several ankle extensors in the cat, suggesting that the animal's response to peripheral nerve injury may also be aimed at preserving ankle mechanical output. We tested this hypothesis by comparing joint moments and power patterns during walking before and after denervation of soleus and lateral gastrocnemius muscles. Hindlimb kinematics, ground reaction forces and electromyographic activity of selected muscles were recorded during level, downslope (−50%) and upslope (50%) walking before and 1–3 weeks after nerve denervation. Denervation resulted in increased activity of the intact medial gastrocnemius and plantaris muscles, greater ankle dorsiflexion, smaller knee flexion, and the preservation of the peak ankle moment during stance. Surprisingly, ankle positive power generated in the propulsion phase of stance was increased (up to 50%) after denervation in all walking conditions (p < 0.05). The obtained results suggest that the short-term motor compensation to denervation of lateral gastrocnemius and soleus muscles may allow for preservation of mechanical output at the ankle. The additional mechanical energy generated at the ankle during propulsion can result, in part, from increased activity of intact synergists, the use of passive tissues around the ankle and by the tendon action of ankle two-joint muscles and crural fascia. PMID:21411965

Measuring the motor output of the pontomedullary reticular formation in the monkey: do stimulus-triggered averaging and stimulus trains produce comparable results in the upper limbs?

PubMed

Herbert, Wendy J; Davidson, Adam G; Buford, John A

2010-06-01

The pontomedullary reticular formation (PMRF) of the monkey produces motor outputs to both upper limbs. EMG effects evoked from stimulus-triggered averaging (StimulusTA) were compared with effects from stimulus trains to determine whether both stimulation methods produced comparable results. Flexor and extensor muscles of scapulothoracic, shoulder, elbow, and wrist joints were studied bilaterally in two male M. fascicularis monkeys trained to perform a bilateral reaching task. The frequency of facilitation versus suppression responses evoked in the muscles was compared between methods. Stimulus trains were more efficient (94% of PMRF sites) in producing responses than StimulusTA (55%), and stimulus trains evoked responses from more muscles per site than from StimulusTA. Facilitation (72%) was more common from stimulus trains than StimulusTA (39%). In the overall results, a bilateral reciprocal activation pattern of ipsilateral flexor and contralateral extensor facilitation was evident for StimulusTA and stimulus trains. When the comparison was restricted to cases where both methods produced a response in a given muscle from the same site, agreement was very high, at 80%. For the remaining 20%, discrepancies were accounted for mainly by facilitation from stimulus trains when StimulusTA produced suppression, which was in agreement with the under-representation of suppression in the stimulus train data as a whole. To the extent that the stimulus train method may favor transmission through polysynaptic pathways, these results suggest that polysynaptic pathways from the PMRF more often produce facilitation in muscles that would typically demonstrate suppression with StimulusTA.

Effect of Ankle Range of Motion (ROM) and Lower-Extremity Muscle Strength on Static Balance Control Ability in Young Adults: A Regression Analysis

PubMed Central

Kim, Seong-Gil

2018-01-01

Background The purpose of this study was to investigate the effect of ankle ROM and lower-extremity muscle strength on static balance control ability in young adults. Material/Methods This study was conducted with 65 young adults, but 10 young adults dropped out during the measurement, so 55 young adults (male: 19, female: 36) completed the study. Postural sway (length and velocity) was measured with eyes open and closed, and ankle ROM (AROM and PROM of dorsiflexion and plantarflexion) and lower-extremity muscle strength (flexor and extensor of hip, knee, and ankle joint) were measured. Pearson correlation coefficient was used to examine the correlation between variables and static balance ability. Simple linear regression analysis and multiple linear regression analysis were used to examine the effect of variables on static balance ability. Results In correlation analysis, plantarflexion ROM (AROM and PROM) and lower-extremity muscle strength (except hip extensor) were significantly correlated with postural sway (p<0.05). In simple correlation analysis, all variables that passed the correlation analysis procedure had significant influence (p<0.05). In multiple linear regression analysis, plantar flexion PROM with eyes open significantly influenced sway length (B=0.681) and sway velocity (B=0.011). Conclusions Lower-extremity muscle strength and ankle plantarflexion ROM influenced static balance control ability, with ankle plantarflexion PROM showing the greatest influence. Therefore, both contractile structures and non-contractile structures should be of interest when considering static balance control ability improvement. PMID:29760375

Effect of Ankle Range of Motion (ROM) and Lower-Extremity Muscle Strength on Static Balance Control Ability in Young Adults: A Regression Analysis.

PubMed

Kim, Seong-Gil; Kim, Wan-Soo

2018-05-15

BACKGROUND The purpose of this study was to investigate the effect of ankle ROM and lower-extremity muscle strength on static balance control ability in young adults. MATERIAL AND METHODS This study was conducted with 65 young adults, but 10 young adults dropped out during the measurement, so 55 young adults (male: 19, female: 36) completed the study. Postural sway (length and velocity) was measured with eyes open and closed, and ankle ROM (AROM and PROM of dorsiflexion and plantarflexion) and lower-extremity muscle strength (flexor and extensor of hip, knee, and ankle joint) were measured. Pearson correlation coefficient was used to examine the correlation between variables and static balance ability. Simple linear regression analysis and multiple linear regression analysis were used to examine the effect of variables on static balance ability. RESULTS In correlation analysis, plantarflexion ROM (AROM and PROM) and lower-extremity muscle strength (except hip extensor) were significantly correlated with postural sway (p<0.05). In simple correlation analysis, all variables that passed the correlation analysis procedure had significant influence (p<0.05). In multiple linear regression analysis, plantar flexion PROM with eyes open significantly influenced sway length (B=0.681) and sway velocity (B=0.011). CONCLUSIONS Lower-extremity muscle strength and ankle plantarflexion ROM influenced static balance control ability, with ankle plantarflexion PROM showing the greatest influence. Therefore, both contractile structures and non-contractile structures should be of interest when considering static balance control ability improvement.

Directional tuning of human forearm muscle afferents during voluntary wrist movements

PubMed Central

Jones, Kelvin E; Wessberg, Johan; Vallbo, Åke B

2001-01-01

Single unit activity was recorded with the microneurography technique from sixteen spindle afferents and one Golgi tendon organ afferent originating from the forearm extensor muscles. Impulse rates were studied while subjects performed unobstructed aiming movements at the wrist in eight different directions 45 deg apart. In addition, similar imposed movements were performed while the subject was instructed to remain relaxed. Movement amplitudes were about 5 deg and the speed 10–30 deg s−1. Joint movements were translated to movements of a cursor on a monitor to provide visual feedback. Individual spindle afferents modulated their activity over a number of targets, i.e. were broadly tuned, during these aiming movements. The preferred direction for a spindle afferent was the same during both passive and active movements, indicating that the fusimotor effects associated with active contractions had little or no effect on the direction of tuning. The direction of tuning of individual spindle afferents could be predicted from the biomechanically inferred length changes of the parent muscle. Thus spindle afferents responded as stretch receptors, i.e. impulse rates increased with lengthening and decreased with shortening, in active as well as passive movements. Spindles from muscles, which continuously counteracted gravity exhibited a stretch response and directional tuning during the phase of movement alone whereas their position sensitivity was poor. In contrast, spindle afferents from the muscles that had no or minimal antigravity role were directionally tuned during both the dynamic and the static phase of the aiming task and their position sensitivity was substantially higher. In spite of the limited data base from three extensor muscles it could be demonstrated that wrist joint position was remarkably well encoded in the ensemble muscle spindle data. In some cases the ensemble muscle spindle data encoded the instantaneous trajectory of movement as well. PMID:11600696

Temporal patterns of the trunk muscles remain altered in a low back-injured population despite subjective reports of recovery.

PubMed

Moreside, Janice M; Quirk, D Adam; Hubley-Kozey, Cheryl L

2014-04-01

To compare temporal activation patterns from 24 abdominal and lumbar muscles between healthy subjects and those who reported recovery from recent low back injury (LBI). Cross-sectional comparative study. University neuromuscular function laboratory. Healthy adult volunteers (N=81; 30 LBI, 51 asymptomatic subjects). Trunk muscle electromyographic activity was collected during 2 difficulty levels of a supine trunk stability test aimed at challenging lumbopelvic control. Principal component (PC) analysis was applied to determine differences in temporal and/or amplitude electromyographic patterns between groups. Mixed-model analyses of variance were performed on PC scores that explained more than 89% of the variance (α=.05). Four PCs explained 89% and 96% of the variance for the abdominal and back muscles, respectively, with both muscle groups having similar shapes in the first 3 PCs. Significant interactions or group main effects were found for all PC scores except PC4 for the back extensors. Overall activation amplitudes for both the abdominal and back muscles (PC1 scores) were significantly (P<.05) higher for the LBI group, with both abdominal and back muscles of the LBI group demonstrating an increased response to the leg-loading phase (PC2 scores) compared with the asymptomatic group. Differences were also found between groups in their preparatory activity (PC3 scores), with the LBI group having a higher early relative amplitude of abdominal and back extensor activity. Despite perceived readiness to return to work and low pain scores, muscle activation patterns remained altered in this LBI group, including reduced synergistic coactivation and increased overall amplitudes as well as greater relative amplitude differences during specific phases of the movement. Electromyographic measures provide objective information to help guide therapy and may assist with determining the level of healing and return-to-work readiness after an LBI. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Revisiting the anatomy and biomechanics of the anconeus muscle and its role in elbow stability.

PubMed

Pereira, Barry P

2013-07-01

Recent studies have designated the anconeus muscle as an option for use as a pedicled flap for covering soft tissue defects about the elbow, with reported minimal risk of morbidity. This has raised the question as to the importance of the anconeus muscle and as to whether this is truly an accessory muscle that can be sacrificed, or whether the anconeus muscle significantly contributes to elbow and forearm stability? This study revisits the anatomy and biomechanics of the anconeus muscle and aims to investigate the neuromuscular compartments of the anconeus muscle and to determine the changes in the muscle length, fibre length and moment arm over a range of elbow flexion angles for each compartment. An anatomical study on 8 human cadavers (51-77 years of age) was done and a 2-dimensional kinematic elbow model developed to determine changes in the muscle length and moment arm of the muscle related to changes in elbow flexion angles. The muscle was modelled with two possible lines of action, one along the posterior and another on the anterior edge of the muscle as they had different muscle fibre lengths (posterior: average of 32 mm, anterior: average of 20 mm). The anterior edge also had an aponeurosis which was 70% of its length. From 0 to 120° elbow flexion, the length of the posterior and anterior edges increased with a maximum change recorded at 90° elbow flexion (31.7±1.0 mm and 65.3±1.4 mm, respectively). The moment arm is 14-mm at 0° flexion, but between the posterior and anterior edges it decreases at different rates with increasing elbow flexion angle. Beyond 80°, the anterior edge behaves as an elbow flexor, while the posterior edge remains an elbow extensor. The study demonstrates that the anconeus muscle has two neuromuscular compartments each with distinct intramuscular innervations and muscle fibre lengths. The posterior and deep aspect of the muscle functions as an elbow extensor decreasing in influence with increasing elbow flexion angle. The anterior superficial aspect which is adjacent and parallel to the lateral collateral ligaments, would most likely work in unison to provide constraint to the posterolateral stability of the elbow. Copyright © 2012. Published by Elsevier GmbH.

Sensitivity of estimated muscle force in forward simulation of normal walking

PubMed Central

Xiao, Ming; Higginson, Jill

2009-01-01

Generic muscle parameters are often used in muscle-driven simulations of human movement estimate individual muscle forces and function. The results may not be valid since muscle properties vary from subject to subject. This study investigated the effect of using generic parameters in a muscle-driven forward simulation on muscle force estimation. We generated a normal walking simulation in OpenSim and examined the sensitivity of individual muscle to perturbations in muscle parameters, including the number of muscles, maximum isometric force, optimal fiber length and tendon slack length. We found that when changing the number muscles included in the model, only magnitude of the estimated muscle forces was affected. Our results also suggest it is especially important to use accurate values of tendon slack length and optimal fiber length for ankle plantarflexors and knee extensors. Changes in force production one muscle were typically compensated for by changes in force production by muscles in the same functional muscle group, or the antagonistic muscle group. Conclusions regarding muscle function based on simulations with generic musculoskeletal parameters should be interpreted with caution. PMID:20498485

Effects of fatiguing constant versus alternating intensity intermittent isometric muscle actions on maximal torque and neuromuscular responses

PubMed Central

Smith, C.M.; Housh, T.J.; Hill, E.C.; Cochrane, K.C.; Jenkins, N.D.M.; Schmidt, R.J.; Johnson, G.O.

2016-01-01

Objective: To determine the effects of constant versus alternating applications of torque during fatiguing, intermittent isometric muscle actions of the leg extensors on maximal voluntary isometric contraction (MVIC) torque and neuromuscular responses. Methods: Sixteen subjects performed two protocols, each consisting of 50 intermittent isometric muscle actions of the leg extensors with equal average load at a constant 60% MVIC or alternating 40 then 80% (40/80%) MVIC with a work-to-rest ratio of 6-s on and 2-s off. MVIC torque as well as electromyographic signals from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) and mechanomyographic signals from the VL were recorded pretest, immediately posttest, and 5-min posttest. Results: The results indicated that there were no time-related differences between the 60% MVIC and 40/80% MVIC protocols. The MVIC torque decreased posttest (22 to 26%) and remained depressed 5-min posttest (9%). There were decreases in electromyographic frequency (14 to 19%) and mechanomyographic frequency (23 to 24%) posttest that returned to pretest levels 5-min posttest. There were no changes in electromyographic amplitude and mechanomyogrpahic amplitude. Conclusions: These findings suggested that these neuromuscular parameters did not track the fatigue-induced changes in MVIC torque after 5-min of recovery. PMID:27973384

Relationship between strength qualities and short track speed skating performance in young athletes.

PubMed

Felser, S; Behrens, M; Fischer, S; Heise, S; Bäumler, M; Salomon, R; Bruhn, S

2016-02-01

This study analyzed the relationships between isometric as well as concentric maximum voluntary contraction (MVC) strength of the leg muscles and the times as well as speeds over different distances in 17 young short track speed skaters. Isometric as well as concentric single-joint MVC strength and multi-joint MVC strength in a stable (without skates) and unstable (with skates) condition were tested. Furthermore, time during maximum skating performances on ice was measured. Results indicate that maximum torques during eversion and dorsal flexion have a significant influence on skating speed. Concentric MVC strength of the knee extensors was higher correlated with times as well as speeds over the different distances than isometric MVC strength. Multi-joint MVC testing revealed that the force loss between measurements without and with skates amounts to 25%, while biceps femoris and soleus showed decreased muscle activity and peroneus longus, tibialis anterior, as well as rectus femoris exhibited increased muscle activity. The results of this study depict evidence that the skating times and speeds are primarily influenced by concentric MVC strength of the leg extensors. To be able to transfer the strength onto ice in an optimal way, it is necessary to stabilize the knee and ankle joints. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

[Statistical (Poisson) motor unit number estimation. Methodological aspects and normal results in the extensor digitorum brevis muscle of healthy subjects].

PubMed

Murga Oporto, L; Menéndez-de León, C; Bauzano Poley, E; Núñez-Castaín, M J

Among the differents techniques for motor unit number estimation (MUNE) there is the statistical one (Poisson), in which the activation of motor units is carried out by electrical stimulation and the estimation performed by means of a statistical analysis based on the Poisson s distribution. The study was undertaken in order to realize an approximation to the MUNE Poisson technique showing a coprehensible view of its methodology and also to obtain normal results in the extensor digitorum brevis muscle (EDB) from a healthy population. One hundred fourteen normal volunteers with age ranging from 10 to 88 years were studied using the MUNE software contained in a Viking IV system. The normal subjects were divided into two age groups (10 59 and 60 88 years). The EDB MUNE from all them was 184 49. Both, the MUNE and the amplitude of the compound muscle action potential (CMAP) were significantly lower in the older age group (p< 0.0001), showing the MUNE a better correlation with age than CMAP amplitude ( 0.5002 and 0.4142, respectively p< 0.0001). Statistical MUNE method is an important way for the assessment to the phisiology of the motor unit. The value of MUNE correlates better with the neuromuscular aging process than CMAP amplitude does.

Relationship between Joint Position Sense, Force Sense, and Muscle Strength and the Impact of Gymnastic Training on Proprioception

PubMed Central

Kochanowicz, Andrzej

2018-01-01

The aims of this study were (1) to assess the relationship between joint position (JPS) and force sense (FS) and muscle strength (MS) and (2) to evaluate the impact of long-term gymnastic training on particular proprioception aspects and their correlations. 17 elite adult gymnasts and 24 untrained, matched controls performed an active reproduction (AR) and passive reproduction (PR) task and a force reproduction (FR) task at the elbow joint. Intergroup differences and the relationship between JPS, FS, and MS were evaluated. While there was no difference in AR or PR between groups, absolute error in the control group was higher during the PR task (7.15 ± 2.72°) than during the AR task (3.1 ± 1.93°). Mean relative error in the control group was 61% higher in the elbow extensors than in the elbow flexors during 50% FR, while the gymnast group had similar results in both reciprocal muscles. There was no linear correlation between JPS and FS in either group; however, FR was negatively correlated with antagonist MS. In conclusion, this study found no evidence for a relationship between the accuracy of FS and JPS at the elbow joint. Long-term gymnastic training improves the JPS and FS of the elbow extensors. PMID:29670901

Effects of the innervation zone on the time and frequency domain parameters of the surface electromyographic signal.

PubMed

Smith, Cory M; Housh, Terry J; Herda, Trent J; Zuniga, Jorge M; Ryan, Eric D; Camic, Clayton L; Bergstrom, Haley C; Smith, Doug B; Weir, Joseph P; Cramer, Joel T; Hill, Ethan C; Cochrane, Kristen C; Jenkins, Nathaniel D M; Schmidt, Richard J; Johnson, Glen O

2015-08-01

The purposes of the present study were to examine the effects of electrode placements over, proximal, and distal to the innervation zone (IZ) on electromyographic (EMG) amplitude (RMS) and frequency (MPF) responses during: (1) a maximal voluntary isometric contraction (MVIC), and; (2) a sustained, submaximal isometric muscle action. A linear array was used to record EMG signals from the vastus lateralis over the IZ, 30mm proximal, and 30mm distal to the IZ during an MVIC and a sustained isometric muscle action of the leg extensors at 50% MVIC. During the MVIC, lower EMG RMS (p>0.05) and greater EMG MPF (p<0.05) values were recorded over the IZ compared to away from the IZ, however, no differences in slope coefficients for the EMG RMS and MPF versus time relationships over, proximal, and distal to the IZ occurred. Thus, the results of the present study indicated that during an MVIC, EMG RMS and MPF values recorded over the IZ are not comparable to those away from the IZ. However, the rates of fatigue-induced changes in EMG RMS and MPF during sustained, submaximal isometric muscle actions of the leg extensors were the same regardless of the electrode placement locations relative to the IZ. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Extensor indicis proprius tendon transfer using shear wave elastography.

PubMed

Lamouille, J; Müller, C; Aubry, S; Bensamoun, S; Raffoul, W; Durand, S

2017-06-01

The means for judging optimal tension during tendon transfers are approximate and not very quantifiable. The purpose of this study was to demonstrate the feasibility of quantitatively assessing muscular mechanical properties intraoperatively using ultrasound elastography (shear wave elastography [SWE]) during extensor indicis proprius (EIP) transfer. We report two cases of EIP transfer for post-traumatic rupture of the extensor pollicis longus muscle. Ultrasound acquisitions measured the elasticity modulus of the EIP muscle at different stages: rest, active extension, active extension against resistance, EIP section, distal passive traction of the tendon, after tendon transfer at rest and then during active extension. A preliminary analysis was conducted of the distribution of values for this modulus at the various transfer steps. Different shear wave velocity and elasticity modulus values were observed at the various transfer steps. The tension applied during the transfer seemed close to the resting tension if a traditional protocol were followed. The elasticity modulus varied by a factor of 37 between the active extension against resistance step (565.1 kPa) and after the tendon section (15.3 kPa). The elasticity modulus values were distributed in the same way for each patient. The therapeutic benefit of SWE elastography was studied for the first time in tendon transfers. Quantitative data on the elasticity modulus during this test may make it an effective means of improving intraoperative adjustments. Copyright © 2017 SFCM. Published by Elsevier Masson SAS. All rights reserved.

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.

Influence of spaceflight on rat skeletal muscle

NASA Technical Reports Server (NTRS)

Martin, Thomas P.; Edgerton, V. Reggie; Grindeland, Richard E.

1988-01-01

The effect of a 7-day spaceflight (aboard NASA's SL-3) on the size and the metabolism of single fibers from several rat muscles was investigated along with the specificity of these responses as related to the muscle type and the size of fibers. It was found that the loss of mass after flight was varied from 36 percent in the soleus to 15 percent in the extensor digitorum longus. Results of histochemical analyses showed that the succinate dehydrogenase (SDH) activity in muscles of flight-exposed rats was maintained at the control levels, whereas the alpha-glycerol phosphate dehydrogenase (GPD) activity was either maintained or increased. The analyses of the metabolic profiles of ATPase, SDH, and GPD indicated that, in some muscles, there was an increase in the poportion of fast oxidative-glycolytic fibers.

Glucocorticoid sensitivity, disuse, and the regulation of muscle mass

NASA Technical Reports Server (NTRS)

Almon, R. R.; Dubois, D. C.

1983-01-01

A new noninvasive immobilization procedure to be used on rats has been developed to study immobilization-induced muscle hypersensitivity to normal glucocorticoid concentration, subsequent muscle atrophy, and atrophy recovery. The immobilization procedure involves encasing the hind limb in a light-weight plasticlike cast (10 percent the usual plaster weight), completely resistant to animal gnawing. The effects of right-angle immobilization of the ankle on the slow fiber soleus, and the fast fiber extensor digitorum longus, resemble the effects of weightlessness. The increased concentration of glucocorticoid receptor sites in immobilized and denervated muscle is discussed, along with the chronic loss of muscle mass that occurs in practically all dystrophies. It is concluded that lack of mechanical work in a zero gravity environment is a major cause of glucocorticoid hypersensitivity in the body's musculature.

Metabolomic Analysis of Oxidative and Glycolytic Skeletal Muscles by Matrix-Assisted Laser Desorption/IonizationMass Spectrometric Imaging (MALDI MSI)

NASA Astrophysics Data System (ADS)

Tsai, Yu-Hsuan; Garrett, Timothy J.; Carter, Christy S.; Yost, Richard A.

2015-06-01

Skeletal muscles are composed of heterogeneous muscle fibers that have different physiological, morphological, biochemical, and histological characteristics. In this work, skeletal muscles extensor digitorum longus, soleus, and whole gastrocnemius were analyzed by matrix-assisted laser desorption/ionization mass spectrometry to characterize small molecule metabolites of oxidative and glycolytic muscle fiber types as well as to visualize biomarker localization. Multivariate data analysis such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were performed to extract significant features. Different metabolic fingerprints were observed from oxidative and glycolytic fibers. Higher abundances of biomolecules such as antioxidant anserine as well as acylcarnitines were observed in the glycolytic fibers, whereas taurine and some nucleotides were found to be localized in the oxidative fibers.

Effect of hindlimb immobilization on the fatigability of skeletal muscle

NASA Technical Reports Server (NTRS)

Witzmann, F. A.; Kim, D. H.; Fitts, R. H.

1983-01-01

The effect of 6 weeks of disuse atrophy produced by hindlimb immobilization was studied in situ (33.5 C) in the soleus and extensor digitorum longus muscles of rats. The results indicate that disuse causes preferential alterations in the isometric contractile properties of slow-twitch, as opposed to fast-twitch, skeletal muscles. During continuous contractile activity, atrophied muscles were found to have lower ATP levels and an apparent increase in their dependence on anaerobic metabolism, as reflected by the more extensive depletion of glycogen and enhanced lactate formation. Although the atrophied muscles were determined to have fewer cross bridges and thus generated lower tension, the pattern of decline in active cross-bridge formation and tetanic tension during contractile activity was found to proceed in a manner similar to controls.

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.

Hindlimb immobilization - Length-tension and contractile properties of skeletal muscle

NASA Technical Reports Server (NTRS)

Witzmann, F. A.; Kim, D. H.; Fitts, R. H.

1982-01-01

Casts were placed around rat feet in plantar flexion position to immobilize the soleus muscle in a shortened position, while the other foot was fixed in dorsal flexion to set the extensor digitorum longus in a shortened position. The total muscular atrophy and contractile properties were measured at 1, 2, 4, 7, 14, 21, 28, 35, and 42 days after immobilization, with casts being replaced every two weeks. The slow twitch soleus and the fast-twitch vastus lateralis and longus muscles were excised after termination of the experiment. The muscles were then stretched and subjected to electric shock to elicit peak tetanic tension and peak tetanic tension development. Force velocity features of the three muscles were assayed in a series of afterloaded contractions and fiber lengths were measured from subsequently macerated muscle. All muscles atrophied during immobilization, reaching a new steady state by day 21. Decreases in fiber and sarcomere lengths were also observed.