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Sample records for repeated maximal isokinetic

  1. Dynamometric indicators of fatigue from repeated maximal concentric isokinetic plantar flexion contractions are independent of knee flexion angles and age but differ for males and females.

    PubMed

    Hébert-Losier, Kim; Holmberg, Hans-Christer

    2014-03-01

    Sex and age are reported to influence the maximal dynamometric performance of major muscle groups, inclusive of ankle plantar flexors. Knee flexion (KF) also impacts plantar flexion function from where stems use of 0° and 45° angles of KF for clinical assessment of gastrocnemius and soleus, respectively. The influence of KF, sex, and age on dynamometric indicators of plantar flexion fatigue was examined in 28 males and 28 females recruited in 2 different age groups (older and younger than 40 years). Each subject performed 50 maximal concentric isokinetic plantar flexions at 60-degree angle per·second with 0° and 45° angles of KF. Maximal voluntary isometric contractions were determined before and after isokinetic trials and maximal, minimal, and normalized linear slopes of peak power during testing. Main effects of and 2-way interactions between KF, sex, age, and order of testing were explored using mixed-effect models and stepwise regressions. At angles of 0° and 45°, the fatigue indicators in younger and older individuals were similar and not influenced by testing order. However, peak isokinetic power and isometric torque declined to greater extents in males than females and, moreover, KF exerted greater impacts on the absolute plantar flexion performance and maximal-to-minimal reduction in isokinetic power in males. Because KF wielded no pronounced effect on fatigue indicators, this test may perhaps be used over time with no major concern regarding the exact knee angle. Our findings indicate that sex, rather than age, should be considered when interpreting dynamometric indicators of fatigue from repeated maximal concentric isokinetic plantar flexions, for example, when establishing normative values or comparing outcomes.

  2. The Effects of Multiple-Joint Isokinetic Resistance Training on Maximal Isokinetic and Dynamic Muscle Strength and Local Muscular Endurance.

    PubMed

    Ratamess, Nicholas A; Beller, Noah A; Gonzalez, Adam M; Spatz, Gregory E; Hoffman, Jay R; Ross, Ryan E; Faigenbaum, Avery D; Kang, Jie

    2016-03-01

    The transfer of training effects of multiple-joint isokinetic resistance training to dynamic exercise performance remain poorly understood. Thus, the purpose of the present study was to investigate the magnitude of isokinetic and dynamic one repetition-maximum (1RM) strength and local muscular endurance increases after 6 weeks of multiple-joint isokinetic resistance training. Seventeen women were randomly assigned to either an isokinetic resistance training group (IRT) or a non-exercising control group (CTL). The IRT group underwent 6 weeks of training (2 days per week) consisting of 5 sets of 6-10 repetitions at 75-85% of subjects' peak strength for the isokinetic chest press and seated row exercises at an average linear velocity of 0.15 m s(-1) [3-sec concentric (CON) and 3-sec eccentric (ECC) phases]. Peak CON and ECC force during the chest press and row, 1RM bench press and bent-over row, and maximum number of modified push-ups were assessed pre and post training. A 2 x 2 analysis of variance with repeated measures and Tukey's post hoc tests were used for data analysis. The results showed that 1RM bench press (from 38.6 ± 6.7 to 43.0 ± 5.9 kg), 1RM bent-over row (from 40.4 ± 7.7 to 45.5 ± 7.5 kg), and the maximal number of modified push-ups (from 39.5 ± 13.6 to 55.3 ± 13.1 repetitions) increased significantly only in the IRT group. Peak isokinetic CON and ECC force in the chest press and row significantly increased in the IRT group. No differences were shown in the CTL group for any measure. These data indicate 6 weeks of multiple-joint isokinetic resistance training increases dynamic muscle strength and local muscular endurance performance in addition to specific isokinetic strength gains in women. Key pointsMultiple-joint isokinetic resistance training increases dynamic maximal muscular strength, local muscular endurance, and maximal isokinetic strength in women.Multiple-joint isokinetic resistance training increased 1RM strength in the bench press (by

  3. The Effects of Multiple-Joint Isokinetic Resistance Training on Maximal Isokinetic and Dynamic Muscle Strength and Local Muscular Endurance

    PubMed Central

    Ratamess, Nicholas A.; Beller, Noah A.; Gonzalez, Adam M.; Spatz, Gregory E.; Hoffman, Jay R.; Ross, Ryan E.; Faigenbaum, Avery D.; Kang, Jie

    2016-01-01

    The transfer of training effects of multiple-joint isokinetic resistance training to dynamic exercise performance remain poorly understood. Thus, the purpose of the present study was to investigate the magnitude of isokinetic and dynamic one repetition-maximum (1RM) strength and local muscular endurance increases after 6 weeks of multiple-joint isokinetic resistance training. Seventeen women were randomly assigned to either an isokinetic resistance training group (IRT) or a non-exercising control group (CTL). The IRT group underwent 6 weeks of training (2 days per week) consisting of 5 sets of 6-10 repetitions at 75-85% of subjects’ peak strength for the isokinetic chest press and seated row exercises at an average linear velocity of 0.15 m s-1 [3-sec concentric (CON) and 3-sec eccentric (ECC) phases]. Peak CON and ECC force during the chest press and row, 1RM bench press and bent-over row, and maximum number of modified push-ups were assessed pre and post training. A 2 x 2 analysis of variance with repeated measures and Tukey’s post hoc tests were used for data analysis. The results showed that 1RM bench press (from 38.6 ± 6.7 to 43.0 ± 5.9 kg), 1RM bent-over row (from 40.4 ± 7.7 to 45.5 ± 7.5 kg), and the maximal number of modified push-ups (from 39.5 ± 13.6 to 55.3 ± 13.1 repetitions) increased significantly only in the IRT group. Peak isokinetic CON and ECC force in the chest press and row significantly increased in the IRT group. No differences were shown in the CTL group for any measure. These data indicate 6 weeks of multiple-joint isokinetic resistance training increases dynamic muscle strength and local muscular endurance performance in addition to specific isokinetic strength gains in women. Key points Multiple-joint isokinetic resistance training increases dynamic maximal muscular strength, local muscular endurance, and maximal isokinetic strength in women. Multiple-joint isokinetic resistance training increased 1RM strength in the bench press

  4. Agonist and antagonist muscle activation during maximal and submaximal isokinetic fatigue tests of the knee extensors.

    PubMed

    Hassani, A; Patikas, D; Bassa, E; Hatzikotoulas, K; Kellis, E; Kotzamanidis, C

    2006-12-01

    The purpose of this study was to examine the differences in electromyographic activity of agonist and antagonist knee musculature between a maximal and a submaximal isokinetic fatigue protocol. Fourteen healthy males (age: 24.3+/-2.5 years) performed 25 maximal (MIFP) and 60 submaximal (SIFP) isokinetic concentric efforts of the knee extensors at 60 degrees s(-1), across a 90 degrees range of motion. The two protocols were performed a week apart. The EMG activity of vastus medialis (VM), vastus lateralis (VL) and biceps femoris (BF) were recorded using surface electrodes. The peak torque (PT) and average EMG (aEMG) were expressed as percentages of pre-fatigue maximal value. One-way analysis of variance indicated a significant (p<0.05) decline of PT during the maximal (45.7%) and submaximal (46.8%) protocols. During the maximal test, the VM and VL aEMG initially increased and then decreased. In contrast, VM and VL aEMG continuously increased during submaximal testing (p<0.05). The antagonist (BF) aEMG remained constant during maximal test but it increased significantly and then declined during the submaximal testing. The above results indicate that agonist and antagonist activity depends on the intensity of the selected isokinetic fatigue test.

  5. [Reproducibility and Bilateral Symmetry of Maximal Isokinetic Trunk Rotation Strength in Healthy and Active Male Adults].

    PubMed

    Mattes, K; Manzer, S; Kianmarz, Y; Paasch, J

    2016-12-01

    Movements with axial trunk rotation are associated with spinal disease and back pain and may lead to several bilateral adaptations of the trunk muscles, which are another risk factor for back pain. To avoid injury and pain, a targeted preventative training should be implemented to preserve symmetrical strength/forces. The effect analysis of such an intervention requires reliable strength tests to document training progress and enable a clinical assessment. This study aimed to determine the reproducibility of an isokinetic test protocol for maximal trunk rotation strength and the verification of left/right differences of the maximum strength of trunk rotation muscles and hand grip strength. 30 healthy and active male adults (BH = 180.1 ± 5.6 cm, BM = 78.5 ± 8.9 kg, age = 26.5 ± 3.5 years) with no history of back pain were examined in a test-retest design. The participants completed an isokinetic maximum strength test on two different test days (two sets of three concentric contractions, three min set break, angle velocity = 120 °/s) with the same test leader. Reproducibility was evaluated with an intra-class correlation coefficient (ICC (3.1)), standard error of measurement (SEM) and coefficient of repeatability (CR). ICC values of 0.94 - 0.98 on the left and 0.97 - 0.98 on the right were identified for torque, power and work. Mean torque, power and work showed CR coefficients of ± 5.1 Nm or ± 4.0 Nm, ± 11.0 W or ± 8.2 W and ± 9.5 J or ± 6.5 J for right or left rotation. The right-handed participants dominated the sample and had greater maximal hand grip strength, but no left/right trunk muscle asymmetry was found. The test protocol provides reliable data and can be used to characterise trunk rotation strength before and after training interventions in patients suffering from back pain or athletes engaging in sports with unilateral trunk rotation patterns. © Georg Thieme Verlag KG Stuttgart

  6. Metabolic and cardiorespiratory responses to maximal intermittent knee isokinetic exercise in young healthy humans.

    PubMed

    Marzorati, M; Perini, R; Milesi, S; Veicsteinas, A

    2000-03-01

    There have been many studies on the effects of isokinetic exercise on muscle performance in training and rehabilitative programmes. On the other hand, the cardiovascular and metabolic responses elicited by this type of exercise have been poorly investigated. This study was specifically designed to describe the relationships, if any, between metabolic and cardiorespiratory responses and power output during maximal intermittent knee isokinetic exercise when a steady state is reached. A group of 18 healthy subjects (10 men and 8 women, age range 25-30 years) were requested to perform at maximal concentric isokinetic knee extensions/flexions 60 degrees. s(-1) and 180 degrees. s(-1) for 5 min, with a 5-s pause interposed between consecutive repetitions. The power output (W) was calculated; before and during the tasks heart rate (f(c)) and arterial blood pressure (AP(a)) were continuously monitored. Pulmonary ventilation (V(E)) and oxygen uptake (VO(2)) were measured at the 4th and at the 5th min of exercise and blood lactate concentration at rest and at the 3rd min of recovery. From the 4th to the 5th min only a slight decrease in W was observed, both at 60 degrees. s(-1) and 180 degrees. s(-1). The VO(2), V(E), f(c) and AP(a) showed similar values in the last 2 min of exercise, suggesting that a steady state had been reached. The VO(2) increased linearly as a function of +W, showing a significantly steeper slope at 60 degrees. s(-1) than at 180 degrees. s(-1). The f(c), in spite of a large interindividual variation, was linearly related to metabolic demand, and was not affected by angular velocity. Systolic and diastolic AP(a) were not related either to VO(2) or to angular velocity. In conclusion it would appear that the metabolic response to maximal intermittent knee isokinetic exercise resembles that of dynamic exercise. Conversely, the cardiocirculatory responses would seem to reflect a relevant role of the isometric postural component, the importance of which

  7. Are there mode-specific and fatigue-related electromechanical delay responses for maximal isokinetic and isometric muscle actions?

    PubMed

    Smith, Cory M; Housh, Terry J; Hill, Ethan C; Keller, Joshua L; Johnson, Glen O; Schmidt, Richard J

    2017-08-23

    This study used a combined electromyographic, mechanomyographic, and force approach to identify electromechanical delay (EMD) from the onsets of the electromyographic to force signals (EMDE-F), onsets of the electromyographic to mechanomyogrpahic signals (EMDE-M), and onsets of mechanomyographic to force signals (EMDM-F). The purposes of the current study were to examine: (1) differences in EMDE-M, EMDM-F, and EMDE-F from the vastus lateralis between maximal isokinetic and maximal concentric isometric leg extensions; and (2) the effects of fatigue and recovery on EMDE-M, EMDM-F, and EMDE-F. These EMD measures were obtained from twelve men during maximal concentric isokinetic and isometric leg extensions pretest, posttest, and after 3-min and 5-min of recovery from 25 maximal isokinetic leg extensions at 60°s(-1). The results indicated no differences between maximal isokinetic and isometric muscle actions for EMDE-M, EMDM-F, or EMDE-F during the pretest, posttest, 3-min recovery, and 5-min recovery measurements. These findings support the comparison of voluntary EMD measures between studies with different modes of exercise as long as the methodology for the determination of EMD are consistent. There were, however, fatigue-induced pretest to posttest increases in EMDE-M, EMDM-F, and EMDE-F which remained elongated after 3-min of recovery, but returned to pretest values after 5-min of recovery. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. A theoretical analysis of an optimal chainring shape to maximize crank power during isokinetic pedaling.

    PubMed

    Rankin, Jeffery W; Neptune, Richard R

    2008-01-01

    Previous studies have sought to improve cycling performance by altering various aspects of the pedaling motion using novel crank-pedal mechanisms and non-circular chainrings. However, most designs have been based on empirical data and very few have provided significant improvements in cycling performance. The purpose of this study was to use a theoretical framework that included a detailed musculoskeletal model driven by individual muscle actuators, forward dynamic simulations and design optimization to determine if cycling performance (i.e., maximal power output) could be improved by optimizing the chainring shape to maximize average crank power during isokinetic pedaling conditions. The optimization identified a consistent non-circular chainring shape at pedaling rates of 60, 90 and 120 rpm with an average eccentricity of 1.29 that increased crank power by an average of 2.9% compared to a conventional circular chainring. The increase in average crank power was the result of the optimal chainrings slowing down the crank velocity during the downstroke (power phase) to allow muscles to generate power longer and produce more external work. The data also showed that chainrings with higher eccentricity increased negative muscle work following the power phase due to muscle activation-deactivation dynamics. Thus, the chainring shape that maximized average crank power balanced these competing demands by providing enough eccentricity to increase the external work generated by muscles during the power phase while minimizing negative work during the subsequent recovery phase.

  9. Cardiorespiratory Coordination in Repeated Maximal Exercise.

    PubMed

    Garcia-Retortillo, Sergi; Javierre, Casimiro; Hristovski, Robert; Ventura, Josep L; Balagué, Natàlia

    2017-01-01

    Increases in cardiorespiratory coordination (CRC) after training with no differences in performance and physiological variables have recently been reported using a principal component analysis approach. However, no research has yet evaluated the short-term effects of exercise on CRC. The aim of this study was to delineate the behavior of CRC under different physiological initial conditions produced by repeated maximal exercises. Fifteen participants performed 2 consecutive graded and maximal cycling tests. Test 1 was performed without any previous exercise, and Test 2 6 min after Test 1. Both tests started at 0 W and the workload was increased by 25 W/min in males and 20 W/min in females, until they were not able to maintain the prescribed cycling frequency of 70 rpm for more than 5 consecutive seconds. A principal component (PC) analysis of selected cardiovascular and cardiorespiratory variables (expired fraction of O2, expired fraction of CO2, ventilation, systolic blood pressure, diastolic blood pressure, and heart rate) was performed to evaluate the CRC defined by the number of PCs in both tests. In order to quantify the degree of coordination, the information entropy was calculated and the eigenvalues of the first PC (PC1) were compared between tests. Although no significant differences were found between the tests with respect to the performed maximal workload (Wmax), maximal oxygen consumption (VO2 max), or ventilatory threshold (VT), an increase in the number of PCs and/or a decrease of eigenvalues of PC1 (t = 2.95; p = 0.01; d = 1.08) was found in Test 2 compared to Test 1. Moreover, entropy was significantly higher (Z = 2.33; p = 0.02; d = 1.43) in the last test. In conclusion, despite the fact that no significant differences were observed in the conventionally explored maximal performance and physiological variables (Wmax, VO2 max, and VT) between tests, a reduction of CRC was observed in Test 2. These results emphasize the interest of CRC evaluation in

  10. Cardiorespiratory Coordination in Repeated Maximal Exercise

    PubMed Central

    Garcia-Retortillo, Sergi; Javierre, Casimiro; Hristovski, Robert; Ventura, Josep L.; Balagué, Natàlia

    2017-01-01

    Increases in cardiorespiratory coordination (CRC) after training with no differences in performance and physiological variables have recently been reported using a principal component analysis approach. However, no research has yet evaluated the short-term effects of exercise on CRC. The aim of this study was to delineate the behavior of CRC under different physiological initial conditions produced by repeated maximal exercises. Fifteen participants performed 2 consecutive graded and maximal cycling tests. Test 1 was performed without any previous exercise, and Test 2 6 min after Test 1. Both tests started at 0 W and the workload was increased by 25 W/min in males and 20 W/min in females, until they were not able to maintain the prescribed cycling frequency of 70 rpm for more than 5 consecutive seconds. A principal component (PC) analysis of selected cardiovascular and cardiorespiratory variables (expired fraction of O2, expired fraction of CO2, ventilation, systolic blood pressure, diastolic blood pressure, and heart rate) was performed to evaluate the CRC defined by the number of PCs in both tests. In order to quantify the degree of coordination, the information entropy was calculated and the eigenvalues of the first PC (PC1) were compared between tests. Although no significant differences were found between the tests with respect to the performed maximal workload (Wmax), maximal oxygen consumption (VO2 max), or ventilatory threshold (VT), an increase in the number of PCs and/or a decrease of eigenvalues of PC1 (t = 2.95; p = 0.01; d = 1.08) was found in Test 2 compared to Test 1. Moreover, entropy was significantly higher (Z = 2.33; p = 0.02; d = 1.43) in the last test. In conclusion, despite the fact that no significant differences were observed in the conventionally explored maximal performance and physiological variables (Wmax, VO2 max, and VT) between tests, a reduction of CRC was observed in Test 2. These results emphasize the interest of CRC evaluation in

  11. Ascertaining maximal voluntary effort production during isokinetic knee strength testing of anterior cruciate ligament-reconstructed patients.

    PubMed

    Almosnino, Sivan; Dvir, Zeevi; Bardana, Davide D; Diaconescu, Elena D; Stevenson, Joan M

    2014-02-01

    The aim of this study was to assess the performance of prediction rules meant for declaration of efforts as being maximal or not during isokinetic strength testing in a cohort that underwent anterior cruciate ligament reconstruction. Thirty-six individuals performed four sets of six reciprocal concentric knee extension/flexion repetitions at a testing speed of 60 degrees per second through a 60-degree range of motion. The sets consisted of a maximal voluntary effort, two nonmaximal sincere efforts at 50% and 75% of self-perceived maximum, and a set attempting to feign or exaggerate thigh muscle strength deficiencies. Strength curve derived set internal consistency measures, namely, cross-correlation and percent root mean square difference scores, were inputted into the prediction rules, whose performance is reported as specificity and sensitivity percentages. Dependent on the prediction rule used and when expressed on an individual participant basis, the corresponding specificity and sensitivity values ranged from 66.6% to 97.2% and 97.2% to 94.4%, respectively. Using the prediction rules presented in this investigation, clinicians may be able to ascertain maximal effort production during isokinetic testing in those who have undergone surgical reconstruction of their anterior cruciate ligament.

  12. Effects of anatabine and unilateral maximal eccentric isokinetic muscle actions on serum markers of muscle damage and inflammation.

    PubMed

    Jenkins, Nathaniel D M; Housh, Terry J; Cochrane, Kristen C; Bergstrom, Haley C; Traylor, Daniel A; Lewis, Robert W; Buckner, Samuel L; Schmidt, Richard J; Johnson, Glen O; Cramer, Joel T

    2014-04-05

    The purpose of this study was to examine the effects of anatabine supplementation in conjunction with unilateral, maximal eccentric isokinetic muscle actions on serum markers of muscle damage and pro-inflammatory cytokines in humans. Seventeen men (mean ± S.D. age = 22.4 ± 3.2 yrs) participated in this double-blinded, placebo-controlled, crossover study. Participants were randomly assigned to two 10-day conditions (anatabine and placebo) separated by a 2-4 week washout period. After seven days of supplementation, blood was sampled immediately prior to PRE, immediately following POST, and 24, 48, and 72 h after 6 sets of 10 repetitions of unilateral, maximal eccentric isokinetic forearm flexion exercise. Concentrations of serum creatine kinase, lactate dehydrogenase, myoglobin, high sensitivity c-reactive protein, and TNF-α were measured. Creatine kinase, myoglobin, and lactate dehydrogenase increased (P<0.05), while high sensitivity c-reactive protein and TNF-α did not change (P>0.05) after the eccentric exercise during both conditions. Lactate dehydrogenase was higher (P<0.05) during the anatabine condition. The primary findings of this study were two-fold: (a) anatabine had no beneficial effects on traditional markers of muscle damage (creatine kinase, lactate dehydrogenase, and myoglobin) compared to placebo after the eccentric exercise protocol, and (b) the eccentric exercise protocol did not elicit increase in the pro-inflammatory cytokines (c-reactive protein and TNF-α). Future studies are needed to examine the effects of anatabine on naturally-occurring inflammation that is common with aging or obesity. Furthermore, additional research is needed to examine the relationship between muscle damage and inflammation after eccentric exercises of different modes, durations, and intensities.

  13. Assessment of the Quadriceps Femoris Muscle in Women after Injury Induced by Maximal Eccentric Isokinetic Exercise with Low Angular Speed

    PubMed Central

    Serráo, Fábio Viadanna; Serráo, Paula Regina Mendes da Silva; Foerster, Bernd; Tannús, Alberto; Monteiro Pedro, Vanessa; Salvini, Tania F.

    2007-01-01

    The objectives of this study were to propose a model for exercise- induced muscle injury by way of a maximal eccentric isokinetic exercise at low angular speed, and assess the time course of functional recovery of the injured quadriceps femoris muscle from the maximal voluntary contraction (MVC) torque and electrical activity (root mean square - RMS and median frequency - MDF). The effectiveness of the proposed eccentric exercise in inducing injury was assessed from the activity of creatine kinase (CK). In addition, the presence of edema of the quadriceps femoris muscle was assessed by a visual inspection of the intensity of the magnetic resonance imaging (MRI) signal. These measurements were carried out before and after the exercise. Ten healthy women (21.9 ± 1.5) took part in this study. The injury was induced by 4 series of 15 maximal eccentric isokinetic contractions at 5°/s. The MVC torque reduced up to the 4th day after the exercise (p < 0.05). The RMS of the vastus medialis oblique (VMO) and the rectus femoris (RF) muscles decreased on the 2nd (VMO and RF; p < 0.05) and 3rd (RF; p < 0.05) days after. The MDF of the VMO increased immediately after (p < 0.05), whilst the MDF of the RF and VL decreased immediately after (RF; p < 0.05), on the 1st (RF and VL; p < 0.05) and on the 2nd (VL; p < 0.05) days after. The CK activity increased on the 2nd day after (p < 0.05). An increase in the intensity of the MRI signal was observed on the 2nd and 7th days after. In conclusion: 1- the eccentric exercise with low angular speed was effective in inducing injury, 2- the quadriceps femoris already started its functional recovery, as shown by the MVC torque and electrical activity, in the first week after the exercise, despite the presence of an increase in the intensity of the MRI signal. Key pointsThe low angular speed eccentric exercise was effec-tive in inducing injury of the quadriceps femoris muscle, and could be used as a muscle injury induc-ing model in future

  14. Lumbosacral compression in maximal lifting efforts in sagittal plane with varying mechanical disadvantage in isometric and isokinetic modes.

    PubMed

    Kumar, S

    1994-12-01

    Nine normal male subjects (mean age 28.2 years and mean weight 72.6 kg) performed 20 standardized maximal effort lifting tasks. They were asked to perform stoop and squat lifts at half, three-quarters and full individual horizontal reach distances in mid-sagittal plane in isometric and isokinetic modes (fixed velocity 60 cm/s). Both stoop and squat lifts were initiated at the floor level and terminated at the individual's knuckle height keeping the horizontal distance constant throughout the lift. The isometric stoop lifts were performed with hip at 60 degrees and 90 degrees of flexion with hands at preselected reach distances. The isometric squat lifts were performed with knees at 90 degrees and 135 degrees of flexion with hands at similarly preselected reach distances. The force was measured using a Static Dynamic Strength Tester with load cell (SM 1000). The postures were recorded using a two-dimensional Peak Performance System with an event synchronizing unit. The load cell was sampled at 60 Hz and the video filming was done at 60 frames per second. The force and postural data were fed to a biomechanical model (Cheng and Kumar 1991) to extract external moment and lumbosacral compression. The strengths generated in different conditions were significantly different (p < 0.01). The strength variation ranged by up to 73% whereas the lumbosacral compression varied by only up to 15%. A high level of lumbosacral compression was maintained in all conditions.

  15. No effects of oral ribose supplementation on repeated maximal exercise and de novo ATP resynthesis.

    PubMed

    Eijnde, B O; Van Leemputte, M; Brouns, F; Van Der Vusse, G J; Labarque, V; Ramaekers, M; Van Schuylenberg, R; Verbessem, P; Wijnen, H; Hespel, P

    2001-11-01

    A double-blind randomized study was performed to evaluate the effect of oral ribose supplementation on repeated maximal exercise and ATP recovery after intermittent maximal muscle contractions. Muscle power output was measured during dynamic knee extensions with the right leg on an isokinetic dynamometer before (pretest) and after (posttest) a 6-day training period in conjunction with ribose (R, 4 doses/day at 4 g/dose, n = 10) or placebo (P, n = 9) intake. The exercise protocol consisted of two bouts (A and B) of maximal contractions, separated by 15 s of rest. Bouts A and B consisted of 15 series of 12 contractions each, separated by a 60-min rest period. During the training period, the subjects performed the same exercise protocol twice per day, with 3-5 h of rest between exercise sessions. Blood samples were collected before and after bouts A and B and 24 h after bout B. Knee-extension power outputs were approximately 10% higher in the posttest than in the pretest but were similar between P and R for all contraction series. The exercise increased blood lactate and plasma ammonia concentrations (P < 0.05), with no significant differences between P and R at any time. After a 6-wk washout period, in a subgroup of subjects (n = 8), needle-biopsy samples were taken from the vastus lateralis before, immediately after, and 24 h after an exercise bout similar to the pretest. ATP and total adenine nucleotide content were decreased by approximately 25 and 20% immediately after and 24 h after exercise in P and R. Oral ribose supplementation with 4-g doses four times a day does not beneficially impact on postexercise muscle ATP recovery and maximal intermittent exercise performance.

  16. Relationships between isokinetic knee strength, single-sprint performance, and repeated-sprint ability in football players.

    PubMed

    Newman, Mark A; Tarpenning, Kyle M; Marino, Frank E

    2004-11-01

    Previous research has demonstrated that muscular strength of the knee extensors is related to the speed an athlete can produce during a single-sprint performance. Football players, as well as many other athletes on the field and the court, execute multiple sprints during the course of a match. The purpose of this study was to examine the relationships between leg strength, single-sprint speed, and repeated-sprint ability. Thirty-eight football players from 3 codes (soccer, rugby league, rugby union) completed a 12- x 20-m repeated-sprint protocol and were evaluated for peak isokinetic knee extension and flexion torque at 60 degrees .s(-1), 150 degrees .s(-1), and 240 degrees .s(-1). Although single-sprint performance correlated with peak extensor and flexor torque at all velocities, the strongest correlation was observed between relative knee extensor torque at 240 degrees .s(-1) and the initial acceleration phase (0-10 m) of the single-sprint performance (r = -0.714, p < 0.01). However, the data suggest that factors other than strength contribute to repeated-sprint ability. This finding provides new evidence in elucidating the relationship between strength and repeated-sprint performance.

  17. Peak torque and rate of torque development influence on repeated maximal exercise performance: contractile and neural contributions.

    PubMed

    Morel, Baptiste; Rouffet, David M; Saboul, Damien; Rota, Samuel; Clémençon, Michel; Hautier, Christophe A

    2015-01-01

    Rapid force production is critical to improve performance and prevent injuries. However, changes in rate of force/torque development caused by the repetition of maximal contractions have received little attention. The aim of this study was to determine the relative influence of rate of torque development (RTD) and peak torque (T(peak)) on the overall performance (i.e. mean torque, T(mean)) decrease during repeated maximal contractions and to investigate the contribution of contractile and neural mechanisms to the alteration of the various mechanical variables. Eleven well-trained men performed 20 sets of 6-s isokinetic maximal knee extensions at 240° · s(-1), beginning every 30 seconds. RTD, T(peak) and T(mean) as well as the Rate of EMG Rise (RER), peak EMG (EMG(peak)) and mean EMG (EMG(mean)) of the vastus lateralis were monitored for each contraction. A wavelet transform was also performed on raw EMG signal for instant mean frequency (if(mean)) calculation. A neuromuscular testing procedure was carried out before and immediately after the fatiguing protocol including evoked RTD (eRTD) and maximal evoked torque (eT(peak)) induced by high frequency doublet (100 Hz). T(mean) decrease was correlated to RTD and T(peak) decrease (R(²) = 0.62; p<0.001; respectively β=0.62 and β=0.19). RER, eRTD and initial if(mean) (0-225 ms) decreased after 20 sets (respectively -21.1 ± 14.1, -25 ± 13%, and ~20%). RTD decrease was correlated to RER decrease (R(²) = 0.36; p<0.05). The eT(peak) decreased significantly after 20 sets (24 ± 5%; p<0.05) contrary to EMG(peak) (-3.2 ± 19.5 %; p=0.71). Our results show that reductions of RTD explained part of the alterations of the overall performance during repeated moderate velocity maximal exercise. The reductions of RTD were associated to an impairment of the ability of the central nervous system to maximally activate the muscle in the first milliseconds of the contraction.

  18. Peak Torque and Rate of Torque Development Influence on Repeated Maximal Exercise Performance: Contractile and Neural Contributions

    PubMed Central

    Morel, Baptiste; Rouffet, David M.; Saboul, Damien; Rota, Samuel; Clémençon, Michel; Hautier, Christophe A.

    2015-01-01

    Rapid force production is critical to improve performance and prevent injuries. However, changes in rate of force/torque development caused by the repetition of maximal contractions have received little attention. The aim of this study was to determine the relative influence of rate of torque development (RTD) and peak torque (Tpeak) on the overall performance (i.e. mean torque, Tmean) decrease during repeated maximal contractions and to investigate the contribution of contractile and neural mechanisms to the alteration of the various mechanical variables. Eleven well-trained men performed 20 sets of 6-s isokinetic maximal knee extensions at 240°·s-1, beginning every 30 seconds. RTD, Tpeak and Tmean as well as the Rate of EMG Rise (RER), peak EMG (EMGpeak) and mean EMG (EMGmean) of the vastus lateralis were monitored for each contraction. A wavelet transform was also performed on raw EMG signal for instant mean frequency (ifmean) calculation. A neuromuscular testing procedure was carried out before and immediately after the fatiguing protocol including evoked RTD (eRTD) and maximal evoked torque (eTpeak) induced by high frequency doublet (100 Hz). Tmean decrease was correlated to RTD and Tpeak decrease (R²=0.62; p<0.001; respectively β=0.62 and β=0.19). RER, eRTD and initial ifmean (0-225 ms) decreased after 20 sets (respectively -21.1±14.1, -25±13%, and ~20%). RTD decrease was correlated to RER decrease (R²=0.36; p<0.05). The eTpeak decreased significantly after 20 sets (24±5%; p<0.05) contrary to EMGpeak (-3.2±19.5 %; p=0.71). Our results show that reductions of RTD explained part of the alterations of the overall performance during repeated moderate velocity maximal exercise. The reductions of RTD were associated to an impairment of the ability of the central nervous system to maximally activate the muscle in the first milliseconds of the contraction. PMID:25901576

  19. Persistence of long term isokinetic strength deficits in subjects with lateral ankle sprain as measured with a protocol including maximal preloading.

    PubMed

    Perron, Marc; Moffet, Hélène; Nadeau, Sylvie; Hébert, Luc J; Belzile, Sylvain

    2014-12-01

    The assessment of muscle function is a cornerstone in the management of subjects who have sustained a lateral ankle sprain. The ankle range of motion being relatively small, the use of preloading allows to measure maximal strength throughout the whole amplitude and therefore to better characterize ankle muscles weaknesses. This study aimed to assess muscle strength of the injured and uninjured ankles in subjects with a lateral ankle sprain, to document the timeline of strength recovery, and to determine the influence of sprain grade on strength loss. Maximal torque of the periarticular muscles of the ankle in a concentric mode using a protocol with maximal preloading was tested in 32 male soldiers at 8 weeks and 6 months post-injury. The evertor muscles of the injured ankles were weaker than the uninjured ones at 8 weeks and 6 months post-injury (P<0.0001, effect size=0.31-0.42). Muscle weaknesses also persisted in the plantarflexors of the injured ankles at 8 weeks (P=0.0014, effect size=0.52-0.58) while at 6 months, only the subjects with a grade II sprain displayed such weaknesses (P<0.0001, effect size 0.27-0.31). The strength of the invertor and dorsiflexor muscles did not differ between sides. The use of an isokinetic protocol with preloading demonstrates significant but small strength deficits in the evertor and plantarflexor muscles. These impairments may contribute to the high incidence of recurrence of lateral ankle sprain in very active individuals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Exhaustive computation of exact duplications via super and non-nested local maximal repeats.

    PubMed

    Taillefer, Eddy; Miller, Jonathan

    2014-02-01

    We propose and implement a method to obtain all duplicated sequences (repeats) from a chromosome or whole genome. Unlike existing approaches our method makes it possible to simultaneously identify and classify repeats into super, local, and non-nested local maximal repeats. Computation verification demonstrates that maximal repeats for a genome of several gigabases can be identified in a reasonable time, enabling us to identified these maximal repeats for any sequenced genome. The algorithm used for the identification relies on enhanced suffix array data structure to achieve practical space and time efficiency, to identify and classify the maximal repeats, and to perform further post-processing on the identified duplicated sequences. The simplicity and effectiveness of the implementation makes the method readily extendible to more sophisticated computations. Maxmers can be exhaustively accounted for in few minutes for genome sequences of dozen megabases in length and in less than a day or two for genome sequences of few gigabases in length. One application of duplicated sequence identification is to the study of duplicated sequence length distributions, which our found to exhibit for large lengths a persistent power-law behavior. Variation of estimated exponents of this power law are studied among different species and successive assembly release versions of the same species. This makes the characterization of the power-law regime of sequenced genomes via maximal repeats identification and classification, an important task for the derivation of models that would help us to elucidate sequence duplication and genome evolution.

  1. [Reliability and validity of the analysis of hand grip and pinch force in isometric and isokinetic conditions].

    PubMed

    Benaglia, P G; Franchignoni, F; Ferriero, G; Zebellin, G; Sartorio, F

    1999-01-01

    Strength measurement of the hand grip is at the core of most protocols of functional assessment of the upper limb and in rehabilitation plays a major role in the analysis of treatment efficacy and patients' occupational ability. The aims of this study were to: a) verify the repeatability of strength measurements made during performance of the hand grip and three types of pinch, carried out under isometric and isokinetic conditions; b) compare maximal isometric strength with the corresponding isokinetic value for each of the manoeuvres studied; c) investigate the correlations between the strength expressed in the different manoeuvres, under both isometric and isokinetic conditions. We studied 14 voluntary subjects over three sessions conducted at 48-hr intervals, employing a computerized isokinetic dynamometer Lido WorkSet equipped with device N(o) 21 for the study of pinch (lateral pinch, pulp pinch, chuck pinch) and device N(o) 52 for the grip study. Isometric contractions resulted stronger than isokinetic ones, and the hand grip was found to be the manoeuvre able to produce most strength. The repeatability of each strength measurement test over the three days was high (Intraclass Correlation Coefficients: 0.89-0.93). Correlations between the isometric and isokinetic performance for each of the manoeuvres examined were always high (Pearson's r coefficients: 0.89-0.95) as were those between the different manoeuvres, whether performed in isometric or isokinetic modality (r: 0.60-0.94).

  2. Effects of repeated bouts of squatting exercise on sub-maximal endurance running performance.

    PubMed

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

    2013-02-01

    It is well established that exercise-induced muscle damage (EIMD) has a detrimental effect on endurance exercise performed in the days that follow. However, it is unknown whether such effects remain after a repeated bout of EIMD. Therefore, the purpose of this study was to examine the effects of repeated bouts of muscle-damaging exercise on sub-maximal running exercise. Nine male participants completed baseline measurements associated with a sub-maximal running bout at lactate turn point. These measurements were repeated 24-48 h after EIMD, comprising 100 squats (10 sets of 10 at 80 % body mass). Two weeks later, when symptoms from the first bout of EIMD had dissipated, all procedures performed at baseline were repeated. Results revealed significant increases in muscle soreness and creatine kinase activity and decreases in peak knee extensor torque and vertical jump performance at 24-48 h after the initial bout of EIMD. However, after the repeated bout, symptoms of EIMD were reduced from baseline at 24-48 h. Significant increases in oxygen uptake (.VO2), minute ventilation (.VE), blood lactate ([BLa]), rating of perceived exertion (RPE), stride frequency and decreases in stride length were observed during sub-maximal running at 24-48 h following the initial bout of EIMD. However, following the repeated bout of EIMD, .VO2, .VE, [BLa], RPE and stride pattern responses during sub-maximal running remained unchanged from baseline at all time points. These findings confirm that a single resistance session protects skeletal muscle against the detrimental effects of EIMD on sub-maximal running endurance exercise.

  3. Efficient maximal repeat finding using the burrows-wheeler transform and wavelet tree.

    PubMed

    Külekci, M Oğuzhan; Vitter, Jeffrey Scott; Xu, Bojian

    2012-01-01

    Finding repetitive structures in genomes and proteins is important to understand their biological functions. Many data compressors for modern genomic sequences rely heavily on finding repeats in the sequences. The notion of maximal repeats captures all the repeats in the data in a space-efficient way. Prior work on maximal repeat finding used either a suffix tree or a suffix array along with other auxiliary data structures. Their space usage is 19--50 times the text size with the best engineering efforts, prohibiting their usability on massive data. Our technique uses the Burrows-Wheeler Transform and wavelet trees. For data sets consisting of natural language texts, the space usage of our method is no more than three times the text size. For genomic sequences stored using one byte per base, the space usage is less than double the sequence size. Our method is also orders of magnitude faster than the prior methods for processing massive texts, since the prior methods must use external memory. For the first time, our method enables a desktop computer with 8GB internal memory to find all the maximal repeats in the whole human genome in less than 17 hours. We have implemented our method as general-purpose open-source software for public use.

  4. Repeated maximal eccentric actions causes long-lasting disturbances in movement control.

    PubMed

    Bottas, Reijo; Linnamo, Vesa; Nicol, Caroline; Komi, Paavo V

    2005-05-01

    This study examined acute and long-lasting effects of fatigue and muscle damage on fast and accurate elbow flexion and extension target movements (TM) with eight male students. An isokinetic machine was used to perform 100 maximal eccentric and concentric elbow flexions at 4-week intervals. Movement range was 40-170 degrees in eccentric exercise (ECCE) and 170-40 degrees in concentric exercise (CONE), with an angular velocity of 2 rad s(-1). TM was performed in sitting position with the right forearm fixed to lever arm above protractor. Subjects performed TM in horizontal plane (amplitude 60 degrees ) by visual feedback of movement from a television monitor. Surface EMG was recorded from the biceps brachii and triceps brachii muscles. TM measurements and serum creatine kinase (CK) determinations were conducted before, after, 0.5 h, 2 days, and 7 days after both exercises. Blood lactate was taken before, after, and 0.5 h after the exercises. Both ECCE and CONE led to a large decline in maximal voluntary contractions, but the recovery was slower after ECCE when it remained incomplete even until day 7 post-exercise. Lactate increased (P < 0.001) similarly after both exercises. Delayed-onset muscle soreness peaked on day 2 and CK peaked on day 7 after ECCE. Exhaustive eccentric exercise of agonistic muscles impaired the flexion TM performance, and had a long-duration modulation effect on the triphasic EMG activity pattern of flexion and extension TM. In the acute phase, the observed changes in performance and in the EMG patterns are suggested to be related to metabolic changes via III and IV muscle afferents. The delayed recovery, on the other hand, may be related to problems in the proprioceptive feedback caused by muscle damage.

  5. Influence of repeated maximal exercise testing on biomarkers and fatigue in sarcoidosis.

    PubMed

    Braam, A W E; de Haan, S N; Vorselaars, A D M; Rijkers, G T; Grutters, J C; van den Elshout, F J J; Korenromp, I H E

    2013-10-01

    Fatigue in the immune mediated inflammatory disease sarcoidosis is thought to be associated with impaired exercise tolerance. This prospective study assessed fatigue and recuperative capacity after repeated exercise, and examined whether changing concentrations in biomarkers upon exercise are associated with fatigue. Twenty sarcoidosis patients and 10 healthy volunteers performed maximal cardiopulmonary exercise tests on two successive days. Concentrations of cytokines, stress hormones, ACE and CK were assessed before and after the two exercise tests, and 3 days thereafter. All participants completed a sleep diary. Severely fatigued patients showed significant lower VO2 max (p=0.038, p=0.022) and maximal workload (p=0.034, p=0.028) on both exercise tests compared to healthy controls. No impairment of maximal exercise testing was demonstrated during the second cycling test in any group. Fatigue was not correlated with changes in concentrations of biomarkers upon exercise. Severely fatigued patients rated both tests as significantly more fatiguing, and reported significant lower mean subjective night sleeping time during the testing period. Fatigue in sarcoidosis patients cannot be objectified by reduction of exercise capacity after repeated maximal exercise testing, and is not correlated with significant changes in biomarkers. Severe fatigue is only and consistently featured by patient reported outcomes. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Fatigue-induced dissociation between rate of force development and maximal force across repeated rapid contractions.

    PubMed

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

    2017-08-01

    We examined whether the presence of fatigue induced by prolonged running influenced the time courses of force generating capacities throughout a series of intermittent rapid contractions. Thirteen male amateur runners performed a set of 15 intermittent isometric rapid contractions of the knee extensor muscles, (3s/5s on/off) the day before (PRE) and immediately after (POST) a half marathon. The maximal voluntary contraction force, rate of force development (RFDpeak), and their ratio (relative RFDpeak) were calculated. At POST, considering the first (out of 15) repetition, the maximal force and RFDpeak decreased (p<0.0001) at the same extent (by 22±6% and 24±22%, respectively), resulting in unchanged relative RFDpeak (p=0.6). Conversely, the decline of RFDpeak throughout the repetitions was more pronounced at POST (p=0.02), thus the decline of relative RFDpeak was more pronounced (p=0.007) at POST (-25±13%) than at PRE (-3±13%). The main finding of this study was that the fatigue induced by a half-marathon caused a more pronounced impairment of rapid compared to maximal force in the subsequent intermittent protocol. Thus, the fatigue-induced impairment in rapid muscle contractions may have a greater effect on repeated, rather than on single, attempts of maximal force production. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. An adequate interset rest period for strength recovery during a common isokinetic test.

    PubMed

    Blazquez, Ivan N; Warren, Barbara L; O'Hanlon, Ann M; Silvestri, Lynette R

    2013-07-01

    Isokinetic testing is used in rehabilitation settings on a regular basis; yet, there is a lack of consistency in rest period usage among protocols. Furthermore, the allotment of rest periods has been arbitrary (e.g., 30, 60, 90 seconds or more). This investigation examines the work:rest ratio as an effective method of standardizing rest periods in isokinetic testing. The purpose of this study was to establish an adequate rest period that would allow reproducibility of strength during a common isokinetic strength test. Twenty-seven healthy college-aged men (age, 23 ± 3.8 years; body weight, 79.54 ± 11.09 kg) were tested on 5 separate occasions: 2 familiarization sessions and 3 experimental sessions. Each subject performed a knee extension/flexion isokinetic strength protocol (Cybex NORM; Lumex, Inc., Ronkonkoma, NY, USA) to determine peak torque by performing 5 maximal reciprocal repetitions at each ascending velocity of 60, 180, and 300°·s. Work:rest ratios of 1:3, 1:8, and 1:12 were counterbalanced between sets. A 3 × 3 repeated measures analysis of variance was used to analyze the data. A significance level of α ≤ 0.05 was used for all tests. There was no significant difference in either knee extension or knee flexion peak torque when comparing work:rest ratios. These findings suggest that a 1:3 work:rest ratio is sufficient during a common isokinetic strength test.

  8. The exercise intensity at maximal oxygen uptake (i⩒O2max): Methodological issues and repeatability.

    PubMed

    Merry, Kevin L; Glaister, Mark; Howatson, Glyn; Van Someren, Ken

    2016-11-01

    The minimum exercise intensity that elicits ⩒O2max (i⩒O2max) is an important variable associated with endurance exercise performance. i⩒O2max is usually determined during a maximal incremental exercise test; however, the magnitude and duration of the increments used influence the i⩒O2max value produced by a given test. The aims of this study were twofold. The first was to investigate whether the i⩒O2max value produced by a single cycle ergometer test (i⩒O2max(S)) was repeatable. The second was to determine if i⩒O2max(S) represents the minimum intensity at which ⩒O2max is elicited when compared to a refined i⩒O2max value (i⩒O2max(R)) derived from repeated tests. Seventeen male cyclists (age 33.9 ± 7.7 years, body mass 80.9 ± 10.2 kg, height 1.82 ± 0.05 m; VO2max 4.27 ± 0.62 L min(-1)) performed four maximal incremental tests for the determination of i⩒O2max(S) and i⩒O2max(R) (3 min stages; 20 W increments). Trials 1 and 2 were identical and used for assessing the repeatability of i⩒O2max(S), trials 3 and 4 began at different intensities and were used to determine i⩒O2max(R). i⩒O2max(S) showed good test-retest repeatability for i⩒O2max (CV = 4.1%; ICC = 0.93), VO2max (CV = 6.3%; ICC = 0.88) and test duration (CV = 6.7%; ICC = 0.89). There was no significant difference between i⩒O2max(S) and i⩒O2max(R) (303 ± 40 W vs. 301 ± 42 W) (P < .05). The present results suggest that i⩒O2max determined directly during a maximal incremental test is repeatable and provides a very good estimate of the minimum exercise intensity that elicits ⩒O2max.

  9. Knee Extensor Electromyographic Activity-to-Work Ratio is Greater With Isotonic Than Isokinetic Contractions.

    PubMed

    Schmitz, Randy J.; Westwood, Kevin C.

    2001-12-01

    OBJECTIVE: To determine whether isotonic or isokinetic contractions produced greater electromyographic (EMG) activity per unit of work during isotonic and isokinetic knee-extension exercise. DESIGN AND SETTING: Subjects performed three 3-second maximal voluntary isometric contractions of the dominant knee extensors for EMG normalization. Exercise testing performed on the Biodex System 3 Dynamometer involved 10 isokinetic contractions at 180 degrees.s(-1) and 10 isotonic contractions with the resistance set at 50% of the previously recorded maximal voluntary isometric contraction. SUBJECTS: Recreationally active college students (10 men and 11 women). MEASUREMENTS: Surface EMG signals were collected from the vastus medialis and lateralis muscles and then integrated (IEMG) over the concentric phase of each repetition for both exercises. The IEMG was divided by the total work performed during the concentric phase for each exercise (IEMG/W). RESULTS: We analyzed the IEMG/W data using a 1-between (sex), 2-within (exercise and muscle) repeated-measures analysis of variance. There was a significant main effect for exercise, with the isotonic IEMG/W value being significantly greater than the isokinetic IEMG/W value. Additionally, the IEMG/W relationship did not appear to be affected by sex or individual muscle tested. CONCLUSIONS: Per unit of work performed, the isotonic contractions resulted in greater motor unit recruitment or an increased rate of firing, or both. This finding may have implications for the early phase of rehabilitation, when goals include complete motor unit recruitment of injured or atrophied muscles.

  10. Knee Extensor Electromyographic Activity-to-Work Ratio is Greater With Isotonic Than Isokinetic Contractions

    PubMed Central

    Westwood, Kevin C.

    2001-01-01

    Objective: To determine whether isotonic or isokinetic contractions produced greater electromyographic (EMG) activity per unit of work during isotonic and isokinetic knee-extension exercise. Design and Setting: Subjects performed three 3-second maximal voluntary isometric contractions of the dominant knee extensors for EMG normalization. Exercise testing performed on the Biodex System 3 Dynamometer involved 10 isokinetic contractions at 180°·s−1 and 10 isotonic contractions with the resistance set at 50% of the previously recorded maximal voluntary isometric contraction. Subjects: Recreationally active college students (10 men and 11 women). Measurements: Surface EMG signals were collected from the vastus medialis and lateralis muscles and then integrated (IEMG) over the concentric phase of each repetition for both exercises. The IEMG was divided by the total work performed during the concentric phase for each exercise (IEMG/W). Results: We analyzed the IEMG/W data using a 1-between (sex), 2-within (exercise and muscle) repeated-measures analysis of variance. There was a significant main effect for exercise, with the isotonic IEMG/W value being significantly greater than the isokinetic IEMG/W value. Additionally, the IEMG/W relationship did not appear to be affected by sex or individual muscle tested. Conclusions: Per unit of work performed, the isotonic contractions resulted in greater motor unit recruitment or an increased rate of firing, or both. This finding may have implications for the early phase of rehabilitation, when goals include complete motor unit recruitment of injured or atrophied muscles. PMID:12937480

  11. Ingestion of High Molecular Weight Carbohydrate Enhances Subsequent Repeated Maximal Power: A Randomized Controlled Trial

    PubMed Central

    Oliver, Jonathan M.; Almada, Anthony L.; Van Eck, Leighsa E.; Shah, Meena; Mitchell, Joel B.; Jones, Margaret T.; Jagim, Andrew R.; Rowlands, David S.

    2016-01-01

    Athletes in sports demanding repeat maximal work outputs frequently train concurrently utilizing sequential bouts of intense endurance and resistance training sessions. On a daily basis, maximal work within subsequent bouts may be limited by muscle glycogen availability. Recently, the ingestion of a unique high molecular weight (HMW) carbohydrate was found to increase glycogen re-synthesis rate and enhance work output during subsequent endurance exercise, relative to low molecular weight (LMW) carbohydrate ingestion. The effect of the HMW carbohydrate, however, on the performance of intense resistance exercise following prolonged-intense endurance training is unknown. Sixteen resistance trained men (23±3 years; 176.7±9.8 cm; 88.2±8.6 kg) participated in a double-blind, placebo-controlled, randomized 3-way crossover design comprising a muscle-glycogen depleting cycling exercise followed by ingestion of placebo (PLA), or 1.2 g•kg•bw-1 of LMW or HMW carbohydrate solution (10%) with blood sampling for 2-h post-ingestion. Thereafter, participants performed 5 sets of 10 maximal explosive repetitions of back squat (75% of 1RM). Compared to PLA, ingestion of HMW (4.9%, 90%CI 3.8%, 5.9%) and LMW (1.9%, 90%CI 0.8%, 3.0%) carbohydrate solutions substantially increased power output during resistance exercise, with the 3.1% (90% CI 4.3, 2.0%) almost certain additional gain in power after HMW-LMW ingestion attributed to higher movement velocity after force kinematic analysis (HMW-LMW 2.5%, 90%CI 1.4, 3.7%). Both carbohydrate solutions increased post-exercise plasma glucose, glucoregulatory and gut hormones compared to PLA, but differences between carbohydrates were unclear; thus, the underlying mechanism remains to be elucidated. Ingestion of a HMW carbohydrate following prolonged intense endurance exercise provides superior benefits to movement velocity and power output during subsequent repeated maximal explosive resistance exercise. This study was registered with

  12. Ingestion of High Molecular Weight Carbohydrate Enhances Subsequent Repeated Maximal Power: A Randomized Controlled Trial.

    PubMed

    Oliver, Jonathan M; Almada, Anthony L; Van Eck, Leighsa E; Shah, Meena; Mitchell, Joel B; Jones, Margaret T; Jagim, Andrew R; Rowlands, David S

    2016-01-01

    Athletes in sports demanding repeat maximal work outputs frequently train concurrently utilizing sequential bouts of intense endurance and resistance training sessions. On a daily basis, maximal work within subsequent bouts may be limited by muscle glycogen availability. Recently, the ingestion of a unique high molecular weight (HMW) carbohydrate was found to increase glycogen re-synthesis rate and enhance work output during subsequent endurance exercise, relative to low molecular weight (LMW) carbohydrate ingestion. The effect of the HMW carbohydrate, however, on the performance of intense resistance exercise following prolonged-intense endurance training is unknown. Sixteen resistance trained men (23±3 years; 176.7±9.8 cm; 88.2±8.6 kg) participated in a double-blind, placebo-controlled, randomized 3-way crossover design comprising a muscle-glycogen depleting cycling exercise followed by ingestion of placebo (PLA), or 1.2 g•kg•bw-1 of LMW or HMW carbohydrate solution (10%) with blood sampling for 2-h post-ingestion. Thereafter, participants performed 5 sets of 10 maximal explosive repetitions of back squat (75% of 1RM). Compared to PLA, ingestion of HMW (4.9%, 90%CI 3.8%, 5.9%) and LMW (1.9%, 90%CI 0.8%, 3.0%) carbohydrate solutions substantially increased power output during resistance exercise, with the 3.1% (90% CI 4.3, 2.0%) almost certain additional gain in power after HMW-LMW ingestion attributed to higher movement velocity after force kinematic analysis (HMW-LMW 2.5%, 90%CI 1.4, 3.7%). Both carbohydrate solutions increased post-exercise plasma glucose, glucoregulatory and gut hormones compared to PLA, but differences between carbohydrates were unclear; thus, the underlying mechanism remains to be elucidated. Ingestion of a HMW carbohydrate following prolonged intense endurance exercise provides superior benefits to movement velocity and power output during subsequent repeated maximal explosive resistance exercise. This study was registered with

  13. Relation between maximal aerobic power and the ability to repeat sprints in young basketball players.

    PubMed

    Castagna, Carlo; Manzi, Vincenzo; D'Ottavio, Stefano; Annino, Giuseppe; Padua, Elvira; Bishop, David

    2007-11-01

    The aim of this study was to examine the effects of maximal aerobic power (V(.-)O2max peak) level on the ability to repeat sprints (calculated as performance decrement and total sprinting time) in young basketball players. Subjects were 18 junior, well-trained basketball players (age, 16.8 +/- 1.2 years; height, 181.3 +/- 5.7 cm; body mass, 73 +/- 10 kg; V(.-)O2max peak, 59.6 +/- 6.9 ml x kg(-1) x min(-1)). Match analysis and time-motion analysis of competitive basketball games was used to devise a basketball-specific repeated-sprint ability protocol consisting of ten 15-m shuttle run sprints with 30 s of passive recovery. Pre, post, and post plus 3-minute blood lactate concentrations were 2.5 +/- 0.7, 13.6 +/- 3.1, and 14.2 +/- 3.5 mmol x L(-1), respectively. The mean fatigue index (FI) value was 3.4 +/- 2.3% (range, 1.1-9.1%). No significant correlations were found between V(.-)O2max peak and either FI or total sprint time. A negative correlation (r = -0.75, p = 0.01) was found between first-sprint time and FI. The results of this study showed that V(.-)O2max peak is not a predictor of repeated-sprint ability in young basketball players. The high blood lactate concentrations found at the end of the repeated-sprint ability protocol suggest its use for building lactate tolerance in conditioned basketball players.

  14. Effects of active recovery on power output during repeated maximal sprint cycling.

    PubMed

    Bogdanis, G C; Nevill, M E; Lakomy, H K; Graham, C M; Louis, G

    1996-01-01

    The effects of active recovery on metabolic and cardiorespiratory responses and power output were examined during repeated sprints. Male subjects (n = 13) performed two maximal 30-s cycle ergometer sprints, 4 min apart, on two separate occasions with either an active [cycling at 40 (1)% of maximal oxygen uptake; mean (SEM)] or passive recovery. Active recovery resulted in a significantly higher mean power output (W) during sprint 2, compared with passive recovery [W] 603 (17) W and 589 (15) W, P < 0.05]. This improvement was totally attributed to a 3.1 (1.0)% higher power generation during the initial 10 s of sprint 2 following the active recovery (P < 0.05), since power output during the last 20 s sprint 2 was the same after both recoveries. Despite the higher power output during sprint 2 after active recovery, no differences were observed between conditions in venous blood lactate and pH, but peak plasma ammonia was significantly higher in the active recovery condition [205 (23) vs 170 (20) mumol .l-1; P < 0.05]. No differences were found between active and passive recovery in terms of changes in plasma volume or arterial blood pressure throughout the test. However, heart rate between the two 30-s sprints and oxygen uptake during the second sprint were higher for the active compared with passive recovery [148 (3) vs 130 (4) beats.min-1; P < 0.01) and 3.3 (0.1) vs 2.8 (0.1) l.min-1; P < 0.01]. These data suggest that recovery of power output during repeated sprint exercise is enhanced when low-intensity exercise is performed between sprints. The beneficial effects of an active recovery are possibly mediated by an increased blood flow to the previously exercised muscle.

  15. Skeletal muscle fiber type composition and performance during repeated bouts of maximal, concentric contractions

    NASA Technical Reports Server (NTRS)

    Colliander, E. B.; Dudley, G. A.; Tesch, P. A.

    1988-01-01

    Force output and fatigue and recovery patterns were studied during intermittent short-term exercise. 27 men performed three bouts of 30 maximal unilateral knee extensions on 2 different occasions. Blood flow was maintained or occluded during recovery periods (60 s). Blood flow was restricted by inflating a pneumatic cuff placed around the proximal thigh. Muscle biopsies from vastus lateralis were analyzed for identification of fast twitch (FT) and slow twitch (ST) fibers and relative FT area. Peak torque decreased during each bout of exercise and more when blood flow was restricted during recovery. Initial peak torque (IPT) and average peak torque (APT) decreased over the three exercise bouts. This response was 3 fold greater without than with blood flow during recovery. IPT and APT decreased more in individuals with mainly FT fibers than in those with mainly ST fibers. It is suggested that performance during repeated bouts of maximal concentric contractions differs between individuals with different fiber type composition. Specifically, in high intensity, intermittent exercise with emphasis on anaerobic energy release a high FT composition may not necessarily be advantageous for performance.

  16. Skeletal muscle fiber type composition and performance during repeated bouts of maximal, concentric contractions

    NASA Technical Reports Server (NTRS)

    Colliander, E. B.; Dudley, G. A.; Tesch, P. A.

    1988-01-01

    Force output and fatigue and recovery patterns were studied during intermittent short-term exercise. 27 men performed three bouts of 30 maximal unilateral knee extensions on 2 different occasions. Blood flow was maintained or occluded during recovery periods (60 s). Blood flow was restricted by inflating a pneumatic cuff placed around the proximal thigh. Muscle biopsies from vastus lateralis were analyzed for identification of fast twitch (FT) and slow twitch (ST) fibers and relative FT area. Peak torque decreased during each bout of exercise and more when blood flow was restricted during recovery. Initial peak torque (IPT) and average peak torque (APT) decreased over the three exercise bouts. This response was 3 fold greater without than with blood flow during recovery. IPT and APT decreased more in individuals with mainly FT fibers than in those with mainly ST fibers. It is suggested that performance during repeated bouts of maximal concentric contractions differs between individuals with different fiber type composition. Specifically, in high intensity, intermittent exercise with emphasis on anaerobic energy release a high FT composition may not necessarily be advantageous for performance.

  17. Central activation, metabolites, and calcium handling during fatigue with repeated maximal isometric contractions in human muscle.

    PubMed

    Cairns, Simeon P; Inman, Luke A G; MacManus, Caroline P; van de Port, Ingrid G L; Ruell, Patricia A; Thom, Jeanette M; Thompson, Martin W

    2017-08-01

    To determine the roles of calcium (Ca(2+)) handling by sarcoplasmic reticulum (SR) and central activation impairment (i.e., central fatigue) during fatigue with repeated maximal voluntary isometric contractions (MVC) in human muscles. Contractile performance was assessed during 3 min of repeated MVCs (7-s contraction, 3-s rest, n = 17). In ten participants, in vitro SR Ca(2+)-handling, metabolites, and fibre-type composition were quantified in biopsy samples from quadriceps muscle, along with plasma venous [K(+)]. In 11 participants, central fatigue was compared using tetanic stimulation superimposed on MVC in quadriceps and adductor pollicis muscles. The decline of peak MVC force with fatigue was similar for both muscles. Fatigue resistance correlated directly with % type I fibre area in quadriceps (r = 0.77, P = 0.009). The maximal rate of ryanodine-induced Ca(2+)-release and Ca(2+)-uptake fell by 31 ± 26 and 28 ± 13%, respectively. The tetanic force depression was correlated with the combined reduction of ATP and PCr, and increase of lactate (r = 0.77, P = 0.009). Plasma venous [K(+)] increased from 4.0 ± 0.3 to 5.4 ± 0.8 mM over 1-3-min exercise. Central fatigue occurred during the early contractions in the quadriceps in 7 out of 17 participants (central activation ratio fell from 0.98 ± 0.05 to 0.86 ± 0.11 at 1 min), but dwindled at exercise cessation. Central fatigue was seldom apparent in adductor pollicis. Fatigue with repeated MVC in human limb muscles mainly involves peripheral aspects which include impaired SR Ca(2+)-handling and we speculate that anaerobic metabolite changes are involved. A faster early force loss in quadriceps muscle with some participants is attributed to central fatigue.

  18. Surface electromyographic amplitude-to-work ratios during isokinetic and isotonic muscle actions.

    PubMed

    Purkayastha, Sushmita; Cramer, Joel T; Trowbridge, Cynthia A; Fincher, A Louise; Marek, Sarah M

    2006-01-01

    Isokinetic and isotonic resistance training exercises are commonly used to increase strength during musculoskeletal rehabilitation programs. Our study was designed to examine the efficacy of isokinetic and isotonic muscle actions using surface electromyographic (EMG) amplitude-to-work ratios (EMG/WK) and to extend previous findings to include a range of isokinetic velocities and isotonic loads. To examine work (WK), surface EMG amplitude, and EMG/WK during concentric-only maximal isokinetic muscle actions at 60, 120, 180, 240, and 300 degrees /s and isotonic muscle actions at 10%, 20%, 30%, 40%, and 50% of the maximal voluntary isometric contraction (MVIC) torque during leg extension exercises. A randomized, counterbalanced, cross-sectional, repeated-measures design. A university-based human muscle physiology research laboratory. Ten women (mean age = 22.0 +/- 2.6 years) and 10 men (mean age = 20.8 +/- 1.7 years) who were apparently healthy and recreationally active. Using the dominant leg, each participant performed 5 maximal voluntary concentric isokinetic leg extension exercises at randomly ordered angular velocities of 60, 120, 180, 240, and 300 degrees /s and 5 concentric isotonic leg extension exercises at randomly ordered loads of 10%, 20%, 30%, 40%, and 50% of the isometric MVIC. Work was recorded by a Biodex System 3 dynamometer, and surface EMG was recorded from the superficial quadriceps femoris muscles (vastus lateralis, rectus femoris, and vastus medialis) during the testing and was normalized to the MVIC. The EMG/WK ratios were calculated as the quotient of EMG amplitude (muVrms) and WK (J) during the concentric phase of each exercise. Isotonic EMG/WK remained unchanged ( P > .05) from 10% to 50% MVIC, but isokinetic EMG/WK increased ( P < .05) from 60 to 300 degrees /s. Isotonic EMG/WK was greater ( P < .05) than isokinetic EMG/WK for 50% MVIC versus 60 degrees /s, 40% MVIC versus 120 degrees /s, and 30% MVIC versus 180 degrees /s; however, no

  19. Surface Electromyographic Amplitude-to-Work Ratios During Isokinetic and Isotonic Muscle Actions

    PubMed Central

    Purkayastha, Sushmita; Cramer, Joel T; Trowbridge, Cynthia A; Fincher, A. Louise; Marek, Sarah M

    2006-01-01

    Context: Isokinetic and isotonic resistance training exercises are commonly used to increase strength during musculoskeletal rehabilitation programs. Our study was designed to examine the efficacy of isokinetic and isotonic muscle actions using surface electromyographic (EMG) amplitude-to-work ratios (EMG/WK) and to extend previous findings to include a range of isokinetic velocities and isotonic loads. Objective: To examine work (WK), surface EMG amplitude, and EMG/WK during concentric-only maximal isokinetic muscle actions at 60, 120, 180, 240, and 300°/s and isotonic muscle actions at 10%, 20%, 30%, 40%, and 50% of the maximal voluntary isometric contraction (MVIC) torque during leg extension exercises. Design: A randomized, counterbalanced, cross-sectional, repeated-measures design. Setting: A university-based human muscle physiology research laboratory. Patients or Other Participants: Ten women (mean age = 22.0 ± 2.6 years) and 10 men (mean age = 20.8 ± 1.7 years) who were apparently healthy and recreationally active. Intervention(s): Using the dominant leg, each participant performed 5 maximal voluntary concentric isokinetic leg extension exercises at randomly ordered angular velocities of 60, 120, 180, 240, and 300°/s and 5 concentric isotonic leg extension exercises at randomly ordered loads of 10%, 20%, 30%, 40%, and 50% of the isometric MVIC. Main Outcome Measure(s): Work was recorded by a Biodex System 3 dynamometer, and surface EMG was recorded from the superficial quadriceps femoris muscles (vastus lateralis, rectus femoris, and vastus medialis) during the testing and was normalized to the MVIC. The EMG/WK ratios were calculated as the quotient of EMG amplitude (μVrms) and WK (J) during the concentric phase of each exercise. Results: Isotonic EMG/WK remained unchanged ( P > .05) from 10% to 50% MVIC, but isokinetic EMG/WK increased ( P < .05) from 60 to 300°/s. Isotonic EMG/WK was greater ( P < .05) than isokinetic EMG/WK for 50% MVIC versus 60

  20. CHO Mouth Rinsing Improves Neuromuscular Performance During Isokinetic Fatiguing Exercise.

    PubMed

    Bazzucchi, Ilenia; Patrizio, Federica; Felici, Francesco; Nicolò, Andrea; Sacchetti, Massimo

    2016-12-14

    To determine whether repeated CHO mouth rinsing would improve neuromuscular performance during high intensity fatiguing contractions. 18 young men (26.1±5.0 yr; 22.9±1,9 BMI) performed 3 maximal voluntary isometric contractions (MVICPRE). Immediately after, they completed 10 s mouth rinse with either 6.4% maltodextrine solution [MAL] or 7.1% glucose solution [GLU] or water [W] or artificially sweetened solution [PLA] or a control trial with no rinse [CON] in a cross over protocol. 5 sets of 30 isokinetic fatiguing contractions at 180°s(-1) and a MVICPOST with their elbow flexors were performed after each mouth rinse. Mechanical and electromyographic signals (EMG) were recorded from the biceps brachii muscle and parameters of interest analyzed. 1) When rinsing the mouth with a solution containing CHO, independently of the sweetness, isokinetic performance was enhanced as shown by the greater total work achieved in comparison with CON; 2) the decay of torque and mean fiber conduction velocity (MFCV) recorded at the end of the fatiguing task was lower when rinsing the mouth with GLU compared to CON; 3) the torque recorded during the MVICPOST was greater with CHO with respect to CON and this was associated to a lower decay of MFCV. CHO mouth rinse counteracts the fatigue-induced decline in neuromuscular performance, supporting the notion that CHO rinse may activate positive afferent signals able to modify the motor output. Repeated mouth rinsing with sweet and non-sweet CHO-containing solutions can improve neuromuscular performance during an isokinetic intermittent fatiguing task.

  1. Older men are more fatigable than young when matched for maximal power and knee extension angular velocity is unconstrained.

    PubMed

    Dalton, Brian H; Power, Geoffrey A; Paturel, Justin R; Rice, Charles L

    2015-06-01

    The underlying factors related to the divergent findings of age-related fatigue for dynamic tasks are not well understood. The purpose here was to investigate age-related fatigability and recovery between a repeated constrained (isokinetic) and an unconstrained velocity (isotonic) task, in which participants performed fatiguing contractions at the velocity (isokinetic) or resistance (isotonic) corresponding with maximal power. To compare between tasks, isotonic torque-power relationships were constructed prior to and following both fatiguing tasks and during short-term recovery. Contractile properties were recorded from 9 old (~75 years) and 11 young (~25 years) men during three testing sessions. In the first session, maximal power was assessed, and sessions 2 and 3 involved an isokinetic or an isotonic concentric fatigue task performed until maximal power was reduced by 40 %. Compared with young, the older men performed the same number of contractions to task failure for the isokinetic task (~45 contractions), but 20 % fewer for the isotonic task (p < 0.05). Regardless of age and task, maximal voluntary isometric contraction strength, angular velocity, and power were reduced by ~30, ~13, and ~25 %, respectively, immediately following task failure, and only isometric torque was not recovered fully by 10 min. In conclusion, older men are more fatigable than the young when performing a repetitive maximal dynamic task at a relative resistance (isotonic) but not an absolute velocity (isokinetic), corresponding to maximal power.

  2. Effects of four recovery methods on repeated maximal rock climbing performance.

    PubMed

    Heyman, Elsa; DE Geus, Bas; Mertens, Inge; Meeusen, Romain

    2009-06-01

    Considering the development of rock climbing as a competitive sport, we aimed at investigating the influence of four recovery methods on subsequent maximal climbing performance. In a randomly assigned crossover design, 13 female well-trained climbers (27.1 +/- 8.9 yr) came to the climbing center on four occasions separated by 1 wk. On each occasion, they had to perform two climbing tests (C1 and C2) until volitional exhaustion on a prepracticed route (overhanging wall, level 6b). These two tests were separated by 20 min of recovery. Four recovery methods were used in randomized order: passive recovery, active recovery (cycle ergometer, 30-40 W), electromyostimulation on the forearm muscles (bisymmetric TENS current), or cold water immersion of the forearms and arms (three periods of 5 min at 15 +/- 1 degrees C). Climbing tests' performance was reflected by the number of arm movements and climb duration. Using active recovery and cold water immersion, performance at C2 was maintained in comparison with C1, whereas C2 performance was impaired compared with C1 (P< 0.01) using electromyostimulation and passive recovery (recovery method-by-climb interaction, P < 0.05). Blood lactate decreased during recovery, with the greatest decrease occurring during active recovery (time-by-recovery method interaction, P < 0.001). Arms and forearms' skin temperatures were lower throughout the cold water immersion compared with the other three methods (P < 0.001). Active recovery and cold water immersion are two means of preserving performance when repeating acute exhausting climbing trails in female climbers. These positive effects are accompanied by a greater lactate removal and a decrease in subcutaneous tissues temperatures, respectively.

  3. The relationship between maximal oxygen uptake and repeated sprint performance indices in field hockey and soccer players.

    PubMed

    Aziz, A R; Chia, M; Teh, K C

    2000-09-01

    The purpose of this study was to examine the relationship between maximal oxygen uptake and repeated sprint performance in field hockey and soccer players. a descriptive study on the aerobic-anaerobic performance of intermittent team game players. the study was conducted at the Sports Medicine and Research Centre. forty male national team game players (22.6+/-4.2 years; 1.73+/-0.07 m and 63.7+/-6.2 kg) were involved in the study. all subjects completed a treadmill run test to exhaustion to determine maximal oxygen uptake and 8x40 m sprints either on the field or running track to determine repeated sprint ability performance. Body mass-normalised maximal oxygen uptake of 58.0+/-4.9 ml x kg(-1) x min(-1) of the group is comparable to values reported in the literature for team game players. No significant correlations were established between the fastest 40 m sprint time and maximal oxygen uptake (r=-0.21 and -0.08, p>0.05). Moderate correlations were established between maximal oxygen uptake and total time for the eight sprints (r=-0.346 and -0.323; p<0.05). Maximal oxygen uptake was not correlated with the fastest 40 m sprint time but was moderately correlated with total sprint time. Since the shared variance between maximal oxygen uptake and total sprint time was only 12%, improving aerobic fitness further will only be expected to contribute marginally to improving repeated sprint performance of the team game players. It remains possible that a high level of aerobic fitness enhances other aspects of match play in games like soccer and hockey.

  4. The effect of isokinetic exercise on the relationship between blood lactate and muscle fatigue.

    PubMed

    Douris, P C

    1993-01-01

    Exercise velocity may be an important variable in determining the amount of blood lactate accumulation during isokinetic exercise. The purpose of this study was to measure the effects of velocity-specific isokinetic exercise on blood lactate, muscle fatigue index, and rating of perceived exertion and to examine the relationship between blood lactate and muscle fatigue index. Ten experienced recreational weight trainers, aged 20-40 years, took part in a repeated measures design consisting of three separate treatments (constant angular velocity at 30, 120, and 300 degrees/sec performed at maximal effort for 1 minute by the right knee flexors and extensors). Rating of perceived exertion, blood lactate, and muscle fatigue index were measured in response to each treatment. Rating of perceived exertion was equal across all three speeds. Muscle fatigue and blood lactate increased significantly as the velocity of exercise increased. There was also a positive correlation coefficient (r = .82, < or = 0.01) between muscle fatigue index and blood lactate. The data suggested that the magnitude of muscle fatigue index and blood lactate responses are strongly dependent on the velocity of movement utilized during maximal isokinetic exercise, and there is a relationship between muscle fatigue index and blood lactate.

  5. The Effects of Repetitive Overhead Throwing on Shoulder Rotator Isokinetic Work-Fatigue.

    PubMed Central

    Kovaleski, John E.; Ogletree, Tim; Heitman, Robert J.; Norrell, Phillip M.

    2007-01-01

    Background Muscle strength and endurance of the shoulder rotators is important for overhead throwing performance and dynamic glenohumeral stability. Baseball pitching is distinguished as an intermittent activity with explosive, high intensity muscle contractions separated by periods of rest. Rotator cuff muscle performance could acutely decrease due to fatigue associated with bouts of throwing. Objective This study examined the effects of repeated overhead throwing upon isokinetic muscle performance of the shoulder rotators. Methods Repeated-measures analyses of vari-ance were used to compare peak torque, total work, and work-fatigue by muscle group, time, and contraction type. Ten collegiate baseball pitchers underwent isokinetic testing of the internal (IR) and external shoulder (ER) rotators one week before and immediately after a throwing protocol of 60 maximal-effort pitches arranged into four innings of 15 pitches per inning. Isokinetic testing consisted of 12 concentric and eccentric repetitions at 300 deg/sec for internal and external rotation of the throwing extremity. Results The main effect of time and the interaction of muscle group and contraction type were significant for work-fatigue. Post-hoc analysis revealed that subjects had significantly greater eccentric IR work-fatigue (13.3 + 1%) compared to the pre-test (7.3 + 2%). Discussion and Conclusions Throwing-related fatigue affected both muscle groups, especially the IR, which has implications for dynamic glenohumeral stability. Rehabilitation and conditioning programs for competitive baseball pitchers should emphasize eccentric muscle endurance training of the shoulder rotators. PMID:21522204

  6. Isokinetic air sampler

    DOEpatents

    Sehmel, George A.

    1979-01-01

    An isokinetic air sampler includes a filter, a holder for the filter, an air pump for drawing air through the filter at a fixed, predetermined rate, an inlet assembly for the sampler having an inlet opening therein of a size such that isokinetic air sampling is obtained at a particular wind speed, a closure for the inlet opening and means for simultaneously opening the closure and turning on the air pump when the wind speed is such that isokinetic air sampling is obtained. A system incorporating a plurality of such samplers provided with air pumps set to draw air through the filter at the same fixed, predetermined rate and having different inlet opening sizes for use at different wind speeds is included within the ambit of the present invention as is a method of sampling air to measure airborne concentrations of particulate pollutants as a function of wind speed.

  7. Improvement of Repeated-Sprint Ability and Horizontal-Jumping Performance in Elite Young Basketball Players With Low-Volume Repeated-Maximal-Power Training.

    PubMed

    Gonzalo-Skok, Oliver; Tous-Fajardo, Julio; Arjol-Serrano, José Luis; Suarez-Arrones, Luis; Casajús, José Antonio; Mendez-Villanueva, Alberto

    2016-05-01

    To examine the effects of a low-volume repeated-power-ability (RPA) training program on repeated-sprint and change-of- direction (COD) ability and functional jumping performance. Twenty-two male elite young basketball players (age 16.2 ± 1.2 y, height 190.0 ± 10.0 cm, body mass 82.9 ± 10.1 kg) were randomly assigned either to an RPA-training group (n = 11) or a control group (n = 11). RPA training consisted of leg-press exercise, twice a week for 6 wk, of 1 or 2 blocks of 5 sets × 5 repetitions with 20 s of passive recovery between sets and 3 min between blocks with the load that maximized power output. Before and after training, performance was assessed by a repeated-sprint-ability (RSA) test, a repeated-COD-ability test, a hop for distance, and a drop jump followed by tests of a double unilateral hop with the right and left legs. Within-group and between-groups differences showed substantial improvements in slowest (RSAs) and mean time (RSAm) on RSA; best, slowest and mean time on repeated-COD ability; and unilateral right and left hop in the RPA group in comparison with control. While best time on RSA showed no improvement in any group, there was a large relationship (r = .68, 90% CI .43;.84) between the relative decrement in RSAm and RSAs, suggesting better sprint maintenance with RPA training. The relative improvements in best and mean repeated-COD ability were very largely correlated (r = .89, 90% CI .77;.94). Six weeks of lowvolume (4-14 min/wk) RPA training improved several physical-fitness tests in basketball players.

  8. Influence of sex on performance fatigability of the plantar flexors following repeated maximal dynamic shortening contractions.

    PubMed

    Lanning, Amelia C; Power, Geoffrey A; Christie, Anita D; Dalton, Brian H

    2017-10-01

    The purpose was to determine sex differences in fatigability during maximal, unconstrained velocity, shortening plantar flexions. The role of time-dependent measures (i.e., rate of torque development, rate of velocity development, and rate of neuromuscular activation) in such sex-related differences was also examined. By task termination, females exhibited smaller reductions in power and similar changes in rate of neuromuscular activation than males, indicating females were less fatigable than males.

  9. Isokinetic eccentric resistance training prevents loss in mechanical muscle function after running.

    PubMed

    Oliveira, Anderson Souza; Caputo, Fabrizio; Aagaard, Per; Corvino, Rogério Bulhões; Gonçalves, Mauro; Denadai, Benedito Sergio

    2013-09-01

    The aim of the study was to verify whether 8 weeks of resistance training employing maximal isokinetic eccentric (IERT) knee extensor actions would reduce the acute force loss observed after high-intensity treadmill running exercise. It was hypothesized that specific IERT would induce protective effects against muscle fatigue and ultrastructural damages, preventing or reducing the loss in mechanical muscle function after running. Subjects were tested before and after IERT protocol for maximal isometric, concentric and eccentric isokinetic knee extensor strength (60° and 180° s(-1)). In a second session, subjects performed treadmill running (~35 min) and the previously mentioned measurements were repeated immediately after running. Subsequently, subjects were randomized to training (n = 12) consisting of 24 sessions of maximal IERT knee extensors actions at 180° s(-1), or served as controls (n = 8). The effects of acute running-induced fatigue and training on isokinetic and isometric peak torque, and rate of force development (RFD) were investigated. Before IERT, running-induced eccentric torque loss at 180° s(-1) was -8 %, and RFD loss was -11 %. Longitudinal IERT led to reduced or absent acute running-induced losses in maximal IERT torque at 180° s(-1) (+2 %), being significantly reduced compared to before IERT (p < 0.05), however, RFD loss remained at -11 % (p > 0.05). In conclusion, IERT yields a reduced strength loss after high-intensity running workouts, which may suggest a protective effect against fatigue and/or morphological damages. However, IERT may not avoid reductions in explosive muscle actions. In turn, this may allow more intense training sessions to be performed, facilitating the adaptive response to running training.

  10. The effect of liquid carbohydrate ingestion on repeated maximal effort exercise in competitive cyclists.

    PubMed

    Haub, Mark D; Haff, G Gregory; Potteiger, Jeffrey A

    2003-02-01

    We investigated the effects of carbohydrate ingestion during recovery from high-intensity exercise on subsequent high-intensity exercise in trained cyclists. Aerobic power was determined, and the competitive cyclists (N = 7) were familiarized with the 100-kJ test protocol (100 KJ-TEST). The subjects performed a first 100 KJ-TEST (RIDE-1), ingested 0.7 g.(kg body mass)(-1) of Gatorlode (CHO) or placebo (PLC), rested for 60 minutes, and then performed a second 100 KJ-TEST (RIDE-2). Blood samples taken before (PRE-1) and after (POST-1) RIDE-1 and before (PRE-2) and after (POST-2) RIDE-2 were analyzed for plasma glucose ([glucose]), lactate, and nonesterified fatty acids ([NEFA]). No significant differences (p > 0.05) were observed between treatments in time to complete RIDE-1 (CHO = 270.3 +/- 29.0 seconds; PLC = 269.9 +/- 33.0 seconds) and RIDE-2 (CHO = 271.7 +/- 26.6 seconds; PLC = 275.3 +/- 30.6 seconds). Plasma [glucose] significantly decreased during the 60-minute recovery for PLC. There was an interaction effect for [NEFA] during recovery, with [NEFA] increasing for PLC and decreasing for CHO. Carbohydrate ingestion after maximal exercise does not appear to influence subsequent short-duration maximal effort exercise in competitive cyclists but does alter plasma [glucose] and [NEFA] relative to a PLC condition.

  11. Repeated high-speed activities during youth soccer games in relation to changes in maximal sprinting and aerobic speeds.

    PubMed

    Buchheit, M; Simpson, B M; Mendez-Villanueva, A

    2013-01-01

    The aim of this study was to examine in highly-trained young soccer players whether substantial changes in either maximal sprinting speed (MSS) or maximal aerobic speed (as inferred from peak incremental test speed, V(Vam-Eval)) can affect repeated high-intensity running during games. Data from 33 players (14.5±1.3 years), who presented substantial changes in either MSS or V(Vam-Eval) throughout 2 consecutive testing periods (~3 months) were included in the final analysis. For each player, time-motion analyses were performed using a global positioning system (1-Hz) during 2-10 international club games played within 1-2 months from/to each testing period of interest (n for game analyzed=109, player-games=393, games per player per period=4±2). Sprint activities were defined as at least a 1-s run at intensities higher than 61% of individual MSS. Repeated-sprint sequences (RSS) were defined as a minimum of 2 consecutive sprints interspersed with a maximum of 60 s of recovery. Improvements in both MSS and V(Vam-Eval) were likely associated with a decreased RSS occurrence, but in some positions only (e. g., - 24% vs. - 3% for improvements in MSS in strikers vs. midfielders, respectively). The changes in the number of sprints per RSS were less clear but also position-dependent, e. g., +7 to +12% for full-backs and wingers, - 5 to - 7% for centre-backs and midfielders. In developing soccer players, changes in repeated-sprint activity during games do not necessarily match those in physical fitness. Game tactical and strategic requirements are likely to modulate on-field players' activity patterns independently (at least partially) of players' physical capacities.

  12. The Influence of Body Position on Load Range During Isokinetic Knee Extension/Flexion

    PubMed Central

    W. Findley, Brian; E. Brown, Lee; Whitehurst, Michael; Keating, Tedd; P. Murray, Daniel; M. Gardner, Lisa

    2006-01-01

    Isokinetic range of motion (ROM) has three distinct phases: rate of velocity development (RVD), load range (LR), and deceleration (DCC). The purpose of this study was to determine if differences in isokinetic knee extension/flexion LR exist between body positions. Ten subjects (4 males and 6 females, age 29.3 ± 5.4 yrs, ht 1.71 ± 0.10 m, wt 71.9 ± 12.9 kg) volunteered to participate in the seated vs. prone investigation and nine different subjects (4 males and 5 females, age 29.5 ± 6.9 yrs, ht 1.72 ± 0.09 m, wt 69.0 ± 13.8 kg) volunteered to participate in the seated vs. supine study. Each subject completed 3 maximal reciprocal concentric/concentric repetitions of dominant knee extension/flexion on a Biodex System 2 isokinetic dynamometer at 60, 120, 180, 240 and 360 deg·sec-1 in the supine or prone and seated positions. Repeated measures ANOVA revealed that only seated flexion at 360 deg·sec-1 (57.6 ± 1.7 degrees) elicited significantly (p < 0.05) greater LR than prone (49.2 ± 2.8 degrees). No significant differences in LR extension or flexion existed at any velocity between the supine vs. seated positions. ANOVA also demonstrated differences between seated vs. prone torque, work and power at most velocities while there was no difference between seated vs. supine. LR is the only phase of an isokinetic repetition where quantifiable resistance is maintained and this data appears to support that it may not be position-dependent but position may alter traditional performance variables. Key Points Load range is the constant velocity phase where torque is collected. Load range has an inverse relationship with velocity. Load range may not be position dependent for the knee extensors or flexors. PMID:24353457

  13. Effects of Lumbosacral Manipulation on Isokinetic Strength of the Knee Extensors and Flexors in Healthy Subjects: A Randomized, Controlled, Single-Blind Crossover Trial

    PubMed Central

    Sanders, Grant D.; Nitz, Arthur J.; Abel, Mark G.; Symons, T. Brock; Shapiro, Robert; Black, W. Scott; Yates, James W.

    2015-01-01

    Objective The purpose of this study was to investigate the effect of manual manipulations targeting the lumbar spine and/or sacroiliac joint on concentric knee extension and flexion forces. Torque production was measured during isometric and isokinetic contractions. Methods This was a randomized, controlled, single-blind crossover design with 21 asymptomatic, college-aged subjects who had never received spinal manipulation. During 2 separate sessions, subjects’ peak torques were recorded while performing maximal voluntary contractions on an isokinetic dynamometer. Isometric knee extension and flexion were recorded at 60° of knee flexion, in addition to isokinetic measurements obtained at 60°/s and 180°/s. Baseline measurements were acquired before either treatment form of lumbosacral manipulation or sham manipulation, followed by identical peak torque measurements within 5 and 20 minutes posttreatment. Data were analyzed with a repeated measures analysis of variance. Results A statistically significant difference did not occur between the effects of lumbosacral manipulation or the sham manipulation in the percentage changes of knee extension and flexion peak torques at 5 and 20 minutes posttreatment. Similar, nonsignificant results were observed in the overall percentage changes of isometric contractions (spinal manipulation 4.0 ± 9.5 vs sham 1.2 ± 6.3, P = .067), isokinetic contractions at 60°/s (spinal manipulation − 4.0 ± 14.2 vs sham − 0.3 ± 8.2, P = .34), and isokinetic contractions at 180°/s (spinal manipulation − 1.4 ± 13.9 vs sham − 5.5 ± 20.0, P = .18). Conclusion The results of the current study suggest that spinal manipulation does not yield an immediate strength-enhancing effect about the knee in healthy, college-aged subjects when measured with isokinetic dynamometry. PMID:26793035

  14. Effects of Lumbosacral Manipulation on Isokinetic Strength of the Knee Extensors and Flexors in Healthy Subjects: A Randomized, Controlled, Single-Blind Crossover Trial.

    PubMed

    Sanders, Grant D; Nitz, Arthur J; Abel, Mark G; Symons, T Brock; Shapiro, Robert; Black, W Scott; Yates, James W

    2015-12-01

    The purpose of this study was to investigate the effect of manual manipulations targeting the lumbar spine and/or sacroiliac joint on concentric knee extension and flexion forces. Torque production was measured during isometric and isokinetic contractions. This was a randomized, controlled, single-blind crossover design with 21 asymptomatic, college-aged subjects who had never received spinal manipulation. During 2 separate sessions, subjects' peak torques were recorded while performing maximal voluntary contractions on an isokinetic dynamometer. Isometric knee extension and flexion were recorded at 60° of knee flexion, in addition to isokinetic measurements obtained at 60°/s and 180°/s. Baseline measurements were acquired before either treatment form of lumbosacral manipulation or sham manipulation, followed by identical peak torque measurements within 5 and 20 minutes posttreatment. Data were analyzed with a repeated measures analysis of variance. A statistically significant difference did not occur between the effects of lumbosacral manipulation or the sham manipulation in the percentage changes of knee extension and flexion peak torques at 5 and 20 minutes posttreatment. Similar, nonsignificant results were observed in the overall percentage changes of isometric contractions (spinal manipulation 4.0 ± 9.5 vs sham 1.2 ± 6.3, P = .067), isokinetic contractions at 60°/s (spinal manipulation - 4.0 ± 14.2 vs sham - 0.3 ± 8.2, P = .34), and isokinetic contractions at 180°/s (spinal manipulation - 1.4 ± 13.9 vs sham - 5.5 ± 20.0, P = .18). The results of the current study suggest that spinal manipulation does not yield an immediate strength-enhancing effect about the knee in healthy, college-aged subjects when measured with isokinetic dynamometry.

  15. Proprioceptive isokinetic exercise test

    NASA Technical Reports Server (NTRS)

    Dempster, P. T.; Bernauer, E. M.; Bond, M.; Greenleaf, J. E.

    1993-01-01

    Proprioception, the reception of stimuli within the body that indicates position, is an important mechanism for optimal human performance. People exposed to prolonged bed rest, microgravity, or other deconditioning situations usually experience reduced proprioceptor and kinesthetic stimuli that compromise body balance, posture, and equilibrium. A new proprioceptive test is described that utilizes the computer-driven LIDO isokinetic ergometer. An overview of the computer logic, software, and testing procedure for this proprioceptive test, which can be performed with the arms or legs, is described.

  16. The Effect of Stabilization on Isokinetic Knee Extension and Flexion Torque Production

    PubMed Central

    Magnusson, S. Peter; Geismar, Richard A.; Gleim, Gilbert W.; Nicholas, James A.

    1993-01-01

    The purpose of this study was to examine the effect of four methods of stabilization on maximal reciprocal isokinetic knee extension and flexion. Left knee extension/flexion was tested at 60°/s in 20 subjects. Warm-up consisted of five submaximal and one maximal effort followed by three maximal efforts in each of four randomized stabilization conditions: 1) Hands and back stabilization; the trunk was strapped to the back rest and the hands grasped the seat. 2) Back stabilization; the trunk was strapped to the back rest and the hands were folded across the chest. 3) Hand stabilization; the hands grasped the seat and the back rest was removed. 4) No stabilization; the hands were folded across the chest and the back rest was removed. One-way repeated measures ANOVA showed a significant effect of stabilization for knee extension (F(3,57)=17.44, p=.0001) and knee flexion (F(3,57)= 5.37, p=.002). Paired, two-tailed student's t-tests with Bonferroni correction showed that, in knee extension, no stabilization was significantly less than all others, p<.001. In addition, back stabilization was less than hands and back stabilization, p<.005. In knee flexion, no stabilization was significantly less than all others, p<.01. In conclusion, the method of trunk stabilization significantly affected maximal reciprocal isokinetic knee extension/flexion strength measurements. Maximal knee extension/flexion torque production was achieved when the trunk was strapped to the back support and when the hands grasped the seat. ImagesFig 1a.Fig 1b.Fig 1c.Fig 1d. PMID:16558235

  17. Relationship between measured maximal oxygen uptake and aerobic endurance performance with running repeated sprint ability in young elite soccer players.

    PubMed

    Aziz, A R; Mukherjee, S; Chia, M Y K; Teh, K C

    2007-12-01

    The aim of the study was to determine the relationships between maximal oxygen uptake (VO(2max)) in a maximal treadmill run and the aerobic endurance performance in the 20-m multistage shuttle run (MST) test, with the performance indices obtained in the running repeated sprint ability (rRSA) test, in elite youth soccer players. Thirty-seven adolescent male outfield players performed on separate days and in random order the treadmill run test and the MST, to obtain their measured VO(2max) and aerobic endurance performance (via the number of completed shuttles in the MST), respectively. Players also completed the rRSA test of 6x20-m all-out sprints, interspersed with 20 s of active recovery. There was a significant moderate correlation between measured VO(2max) (in L . min(-1) and mL . kg(-1) . min(-1)) and MST results (r=0.43 and 0.54, P<0.05, respectively). There was no significant correlation between measured VO(2max) and aerobic endurance performance with any of the performance indices in the rRSA test (all P>0.05). The moderate association between the measured VO(2max) and MST suggests that both tests were plausibly measuring different aspects of a player's aerobic fitness. The lack of association between measured VO(2max) and aerobic endurance performance in the MST with performance in the rRSA suggests that aerobic fitness per se is poorly associated with performance in the rRSA in elite youth soccer players.

  18. Effects of acute creatine loading with or without carbohydrate on repeated bouts of maximal swimming in high-performance swimmers.

    PubMed

    Theodorou, Apostolos S; Havenetidis, Konstantinos; Zanker, Cathy L; O'Hara, John P; King, Roderick F G J; Hood, Colin; Paradisis, Giorgios; Cooke, Carlton B

    2005-05-01

    The addition of carbohydrate (CHO) to an acute creatine (Cr) loading regimen has been shown to increase muscle total creatine content significantly beyond that achieved through creatine loading alone. However, the potential ergogenic effects of combined Cr and CHO loading have not been assessed. The purpose of this study was to compare swimming performance, assessed as mean swimming velocity over repeated maximal intervals, in high-performance swimmers before and after an acute loading regimen of either creatine alone (Cr) or combined creatine and carbohydrate (Cr + CHO). Ten swimmers (mean +/- SD of age and body mass: 17.8 +/- 1.8 years and 72.3 +/- 6.8 kg, respectively) of international caliber were recruited and were randomized to 1 of 2 groups. Each swimmer ingested five 5 g doses of creatine for 4 days, with the Cr + CHO group also ingesting approximately 100 g of simple CHO 30 minutes after each dose of creatine. Performance was measured on 5 separate occasions: twice at "baseline" (prior to intervention, to assess the repeatability of the performance test), within 48 hours after intervention, and then 2 and 4 weeks later. All subjects swam faster after either dietary loading regimen (p < 0.01, both regimens); however, there was no difference in the extent of improvement of performance between groups. In addition, all swimmers continued to produce faster swim times for up to 4 weeks after intervention. Our findings suggest that no performance advantage was gained from the addition of carbohydrate to a creatine-loading regimen in these high-caliber swimmers.

  19. Thermodynamic limit for isokinetic thermostats

    NASA Astrophysics Data System (ADS)

    Gallavotti, G.; Presutti, E.

    2010-05-01

    Thermostat models in space dimension d =1,2,3 for nonequilibrium statistical mechanics are considered and it is shown that, in the thermodynamic limit, the motions of frictionless thermostats and isokinetic thermostats coincide.

  20. High Altitude Increases Alteration in Maximal Torque but Not in Rapid Torque Development in Knee Extensors after Repeated Treadmill Sprinting

    PubMed Central

    Girard, Olivier; Brocherie, Franck; Millet, Grégoire P.

    2016-01-01

    We assessed knee extensor neuromuscular adjustments following repeated treadmill sprints in different normobaric hypoxia conditions, with special reference to rapid muscle torque production capacity. Thirteen team- and racquet-sport athletes undertook 8 × 5-s “all-out” sprints (passive recovery = 25 s) on a non-motorized treadmill in normoxia (NM; FiO2 = 20.9%), at low (LA; FiO2 = 16.8%) and high (HA; FiO2 = 13.3%) normobaric hypoxia (simulated altitudes of ~1800 m and ~3600 m, respectively). Explosive (~1 s; “fast” instruction) and maximal (~5 s; “hard” instruction) voluntary isometric contractions (MVC) of the knee extensors (KE), with concurrent electromyographic (EMG) activity recordings of the vastus lateralis (VL) and rectus femoris (RF) muscles, were performed before and 1-min post-exercise. Rate of torque development (RTD) and EMG (i.e., Root Mean Square or RMS) rise from 0 to 30, −50, −100, and −200 ms were recorded, and were also normalized to maximal torque and EMG values, respectively. Distance covered during the first 5-s sprint was similar (P > 0.05) in all conditions. A larger (P < 0.05) sprint decrement score and a shorter (P < 0.05) cumulated distance covered over the eight sprints occurred in HA (−8 ± 4% and 178 ± 11 m) but not in LA (−7 ± 3% and 181 ± 10 m) compared to NM (−5 ± 2% and 183 ± 9 m). Compared to NM (−9 ± 7%), a larger (P < 0.05) reduction in MVC torque occurred post-exercise in HA (−14 ± 9%) but not in LA (-12 ± 7%), with no difference between NM and LA (P > 0.05). Irrespectively of condition (P > 0.05), peak RTD (−6 ± 11%; P < 0.05), and normalized peak RMS activity for VL (−8 ± 11%; P = 0.07) and RF (−14 ± 11%; P < 0.01) muscles were reduced post-exercise, whereas reductions (P < 0.05) in absolute RTD occurred within the 0–100 (−8 ± 9%) and 0–200 ms (−10 ± 8%) epochs after contraction onset. After normalization to MVC torque, there was no difference in RTD values

  1. Effects of the bilateral isokinetic strengthening training on functional parameters, gait, and the quality of life in patients with stroke

    PubMed Central

    Büyükvural Şen, Sıdıka; Özbudak Demir, Sibel; Ekiz, Timur; Özgirgin, Neşe

    2015-01-01

    Objective: To evaluate the effects of the bilateral isokinetic strengthening training applied to knee and ankle muscles on balance, functional parameters, gait, and the quality of in stroke patients. Methods: Fifty patients (33 M, 17 F) with subacute-chronic stroke and 30 healthy subjects were included. Stroke patients were allocated into isokinetic and control groups. Conventional rehabilitation program was applied to all cases; additionally maximal concentric isokinetic strengthening training was applied to the knee-ankle muscles bilaterally to the isokinetic group 5 days a week for 3 weeks. Biodex System 3 Pro Multijoint System isokinetic dynamometer was used for isokinetic evaluation. The groups were assessed by Functional Independence Measure, Stroke Specific Quality of Life Scale, Timed 10-Meter Walk Test, Six-Minute Walk Test, Stair-Climbing Test, Timed up&go Test, Berg Balance Scale, and Rivermead Mobility Index. Results: Compared with baseline, the isokinetic PT values of the knee and ankle on both sides significantly increased in all cases. PT change values were significantly higher in the isokinetic group than the control group (P<0.025). Furthermore, the quality of life, gait, balance and mobility index values improved significantly in both groups, besides the increase levels were found significantly higher in the isokinetic group (P<0.025, P<0.05). Conclusion: Bilateral isokinetic strengthening training in addition to conventional rehabilitation program after stroke seems to be effective on strengthening muscles on both sides, improving functional parameters, gait, balance and life quality. PMID:26629238

  2. Effects of the bilateral isokinetic strengthening training on functional parameters, gait, and the quality of life in patients with stroke.

    PubMed

    Büyükvural Şen, Sıdıka; Özbudak Demir, Sibel; Ekiz, Timur; Özgirgin, Neşe

    2015-01-01

    To evaluate the effects of the bilateral isokinetic strengthening training applied to knee and ankle muscles on balance, functional parameters, gait, and the quality of in stroke patients. Fifty patients (33 M, 17 F) with subacute-chronic stroke and 30 healthy subjects were included. Stroke patients were allocated into isokinetic and control groups. Conventional rehabilitation program was applied to all cases; additionally maximal concentric isokinetic strengthening training was applied to the knee-ankle muscles bilaterally to the isokinetic group 5 days a week for 3 weeks. Biodex System 3 Pro Multijoint System isokinetic dynamometer was used for isokinetic evaluation. The groups were assessed by Functional Independence Measure, Stroke Specific Quality of Life Scale, Timed 10-Meter Walk Test, Six-Minute Walk Test, Stair-Climbing Test, Timed up&go Test, Berg Balance Scale, and Rivermead Mobility Index. Compared with baseline, the isokinetic PT values of the knee and ankle on both sides significantly increased in all cases. PT change values were significantly higher in the isokinetic group than the control group (P<0.025). Furthermore, the quality of life, gait, balance and mobility index values improved significantly in both groups, besides the increase levels were found significantly higher in the isokinetic group (P<0.025, P<0.05). Bilateral isokinetic strengthening training in addition to conventional rehabilitation program after stroke seems to be effective on strengthening muscles on both sides, improving functional parameters, gait, balance and life quality.

  3. Not quite so fast: effect of training at 90% sprint speed on maximal and repeated-sprint ability in soccer players.

    PubMed

    Haugen, Thomas; Tonnessen, Espen; Leirstein, Svein; Hem, Erlend; Seiler, Stephen

    2014-12-01

    Abstract The aim of the present study was to investigate the effect of training at an intensity eliciting 90% of maximal sprinting speed on maximal and repeated-sprint performance in soccer. It was hypothesised that sprint training at 90% of maximal velocity would improve soccer-related sprinting. Twenty-two junior club-level male and female soccer players (age 17 ± 1 year, body mass 64 ± 8 kg, body height 174 ± 8 cm) completed an intervention study where the training group (TG) replaced one of their weekly soccer training sessions with a repeated-sprint training session performed at 90% of maximal sprint speed, while the control group (CG) completed regular soccer training according to their teams' original training plans. Countermovement jump, 12 × 20-m repeated-sprint, VO2max and the Yo-Yo Intermittent Recovery Level 1 test were performed prior to and after a 9-week intervention period. No significant between-group differences were observed for any of the performance indices and effect magnitudes were trivial or small. Before rejecting the hypothesis, we recommend that future studies should perform intervention programmes with either stronger stimulus or at other times during the season where total training load is reduced.

  4. Effects of Velocity on Electromyographic, Mechanomyographic, and Torque Responses to Repeated Eccentric Muscle Actions.

    PubMed

    Hill, Ethan C; Housh, Terry J; Camic, Clayton L; Smith, Cory M; Cochrane, Kristen C; Jenkins, Nathaniel D M; Cramer, Joel T; Schmidt, Richard J; Johnson, Glen O

    2016-06-01

    The purposes of this study were to examine the effects of the velocity of repeated eccentric muscle actions on the torque and neuromuscular responses during maximal isometric and eccentric muscle actions. Twelve resistance-trained men performed 30 repeated, maximal, eccentric, isokinetic muscle actions at randomly ordered velocities of 60, 120, or 180°·s on separate days. Maximal voluntary isometric contractions (MVICs) were performed before (pretest) and after (posttest) the repeated eccentric muscle actions on each day. Eccentric isokinetic peak torque (EIPT) values were the averages of the first 3 and last 3 repetitions of the 30 repeated eccentric muscle actions. During the EIPT and MVIC muscle actions, electromyographic (EMG) and mechanomyographic (MMG) amplitude (EMG AMP and MMG AMP) and mean power frequency (EMG MPF and MMG MPF) values were assessed. These results indicated that the repeated eccentric muscle actions had no effects on EIPT, or the EMG AMP, EMG MPF, or MMG MPF values assessed during the EIPT muscle actions, but decreased MMG AMP. The repeated eccentric muscle actions, however, decreased MVIC torque, and also the EMG AMP and MMG MPF values assessed during the MVIC muscle actions, but increased MMG AMP. The results indicated that the velocity of the repeated eccentric muscle actions affected the MVIC torque responses, but not EIPT or any of the neuromuscular parameters. Furthermore, there are differences in the torque and neuromuscular responses for isometric vs. eccentric muscle actions after repeated eccentric muscle actions.

  5. Isokinetic Strength and Endurance During 30-day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bond, M.; Bulbulian, R.

    1994-01-01

    The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle orgometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

  6. Isokinetic strength and endurance during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bulbulian, R.; Bond, M.

    1994-01-01

    The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle ergometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

  7. Isokinetic Strength and Endurance During 30-day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bond, M.; Bulbulian, R.

    1994-01-01

    The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle orgometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

  8. Isokinetic strength and endurance during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bulbulian, R.; Bond, M.

    1994-01-01

    The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle ergometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

  9. Effects of fatigue and recovery on electromechanical delay during isokinetic muscle actions.

    PubMed

    Smith, Cory M; Housh, Terry J; Hill, Ethan C; Keller, Joshua L; Johnson, Glen O; Schmidt, Richard J

    2017-09-21

    To examine muscle-specific differences and the effects of fatigue and recovery on electromechanical delay (EMD) during maximal isokinetic muscle actions. Thirteen men performed maximal isokinetic knee extension muscle actions at 60° s(-1), pretest, posttest, and after 5 min of recovery from 25 maximal isokinetic knee extensions. The onsets of the electromyographic, mechanomyographic, and force signals were used to identify EMD measures from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF). There were posttest increases in all EMD measures for all muscles that returned to pretest levels after 5 min of recovery. There were, however, no differences in EMD measures between the VL and VM. All EMD values from the RF were greater than the VL and VM. These findings suggested muscle-specific differences in EMD and that excitation-contraction coupling failure and increased compliance of the series elastic component occurred posttest, but subsided after 5 min of recovery.

  10. Reduced biceps femoris myoelectrical activity influences eccentric knee flexor weakness after repeat sprint running.

    PubMed

    Timmins, R G; Opar, D A; Williams, M D; Schache, A G; Dear, N M; Shield, A J

    2014-08-01

    The aim of this study was to determine whether declines in knee flexor strength following overground repeat sprints were related to changes in hamstrings myoelectrical activity. Seventeen recreationally active men completed maximal isokinetic concentric and eccentric knee flexor strength assessments at 180°/s before and after repeat sprint running. Myoelectrical activity of the biceps femoris (BF) and medial hamstrings (MHs) was measured during all isokinetic contractions. Repeated measures mixed model [fixed factors = time (pre- and post-repeat sprint) and leg (dominant and nondominant), random factor = participants] design was fitted with the restricted maximal likelihood method. Repeat sprint running resulted in significant declines in eccentric, and concentric, knee flexor strength (eccentric = 26 ± 4 Nm, 15% P < 0.001; concentric 11 ± 2 Nm, 10% P < 0.001). Eccentric BF myoelectrical activity was significantly reduced (10%; P = 0.035). Concentric BF and all MH myoelectrical activity were not altered. The declines in maximal eccentric torque were associated with the change in eccentric BF myoelectrical activity (P = 0.013). Following repeat sprint running, there were preferential declines in the myoelectrical activity of the BF, which explained declines in eccentric knee flexor strength.

  11. The effect of isokinetic testing speed on the reliability of muscle fatigue indicators during a hip abductor-adductor fatigue protocol.

    PubMed

    Gautrey, C N; Watson, T; Mitchell, A

    2013-07-01

    The aim of this study was to investigate the reliability of fatigue indicators calculated from peak torque and total work during isokinetic speeds of 60, 90, 120 and 180° · s-1 during a hip fatigue protocol. 10 males suffering from a history of unilateral functional ankle instability and 10 male healthy controls performed 5 maximal concentric contractions on an isokinetic dynamometer. Following a 4 min rest period subjects were instructed to perform repeated maximal concentric contractions to fatigue, which was defined as 3 consecutive repetitions below 50% of the maximum peak torque value. Each testing speed was randomised with 24 h between speeds. The subjects were asked to return to the laboratory 7 days later to repeat the 4 speeds, with 24 h between speeds. Muscle fatigue was determined for each testing speed by the fatigue index, the percent decrease in performance and the slope of the regression equation. The most reliable fatigue determination method was the slope of the regression equation, when testing at a speed of 120° · s-1. It is recommended that future investigators examine and plot their data before choosing the slope of the regression equation as their fatigue indicator, as a linear model is required. © Georg Thieme Verlag KG Stuttgart · New York.

  12. Neural adaptations to submaximal isokinetic eccentric strength training.

    PubMed

    Barrué-Belou, Simon; Amarantini, David; Marque, Philippe; Duclay, Julien

    2016-05-01

    This study investigated the neural adaptations following submaximal isokinetic eccentric strength training of the plantar flexors. The modulation of electromyographic (EMG) activity and spinal excitability were compared in the soleus muscle (SOL) during isometric, concentric and eccentric maximal voluntary contractions (MVC) before and after submaximal isokinetic eccentric training. Eighteen healthy subjects were divided into a training group (n = 8) and a control group (n = 10). The training protocol consisted of sixteen sessions of isokinetic eccentric strength training during 8 weeks. Normalized EMG was used to assess the activity of SOL and medial gastrocnemius muscle (MG). For SOL, maximal Hoffmann reflex (H-reflex) and compound motor potential were evoked during isometric, concentric and eccentric actions at rest (Hmax and Mmax, respectively) and during MVC (Hsup and Msup, respectively). The results showed that the torque and normalized EMG of SOL significantly increased after training during eccentric (+20.5 and +28.8 %, respectively) and isometric (+18.2 and +23.0 %, respectively) MVC (p < 0.05). Hmax/Mmax and Hsup/Msup ratios were not significantly modified after training for SOL (p > 0.05), and remained significantly depressed during eccentric compared to isometric and concentric actions (p < 0.05). In contrast, no significant difference was observed on normalized EMG of MG (p > 0.05). These results suggested that the increase in voluntary torque after submaximal isokinetic eccentric training can be at least partly ascribed to enhanced neural drive for SOL that does not affect the H-reflex pathway.

  13. Reliability of a 5 x 6-s maximal cycling repeated-sprint test in trained female team-sport athletes.

    PubMed

    McGawley, K; Bishop, D

    2006-11-01

    The present study examined the reliability of work and power measures during a 5 x 6-s cycle ergometer test of repeated-sprint ability. Nine, well-trained, female soccer players performed five, 5 x 6-s repeated-sprint tests on a front-access cycle ergometer on separate days. Sprints were separated by 24 s of active recovery. Absolute measures of total work done (W (tot)), total peak power (PP(tot)), work done during sprint 1 (W (1)) and peak power output during sprint 1 (PP(1)) were recorded. Decrement scores in work done (W (dec)) and peak power output (PP(dec)), and fatigue indices for work done (FI( W )) and peak power (FI( P )), were calculated. Significant improvements in all of the work and power measures were observed between trial 1 and subsequent trials (P < 0.05), but no significant differences were identified between trials 2, 3, 4 and 5. The same was true for increases in the decrement scores. The coefficient of variation (CV) was established to reflect within-subject reproducibility for each variable. The CV was significantly improved by the third trial for work done (W (tot) CV: trials 1-2 = 5.5%; trials 3-4 = 2.8%), peak power (PP(tot) CV: trials 1-2 = 5.1%; trials 3-4 = 2.7%) and performance decrement scores (P < 0.05). The standard error of measurement (SEM) and intraclass correlation coefficient (ICC) were also calculated for each variable and expressed within 95% confidence intervals. It was concluded that two familiarisation trials are optimal for collecting reliable data from a 5 x 6-s repeated-sprint cycling test. Furthermore, due to the large variation around performance decrement it was suggested that decrement scores ought to be interpreted with caution.

  14. Isokinetic exercise: A review of the literature

    NASA Technical Reports Server (NTRS)

    Olree, H. D.; Corbin, B.; Smith, C.

    1978-01-01

    Isokinetic muscle training has all the advantages of isometrics and isotonics while minimizing their deficiencies. By holding the speed of movement constant throughout the full range of motion, isokinetic training devices respond with increased resistance rather than acceleration when the power output of the muscle is increased. Isokinetic training is superior to isometric and isotonic training with respect to increases in strength, specificity of training, desirable changes in motor performance tasks, lack of muscle soreness, and decreases in relative body fat.

  15. Postoperative eccentric and concentric isokinetic strength for the shoulder rotators in the scapular and neutral planes.

    PubMed

    Hartsell, H D; Forwell, L

    1997-01-01

    Considerable variability exists for isokinetic testing of the shoulder rotators, leaving the clinician in a quandry concerning the most appropriate method for patient evaluation. The purpose of this study was to evaluate concentric and eccentric rotational strength in the scapular and neutral planes for the surgical and nonsurgical shoulders. Fifteen males consented to be tested during a 90-minute isokinetic session. Both shoulders for each patient were tested concentrically (240 degrees/sec) and eccentrically (120 degrees/sec) in the scapular and neutral planes. Patient positioning was maintained through the use of a goniometer, plumb line, and floor grid system. Following a warmup, five maximal effort reciprocal internal and external rotation concentric and eccentric contractions were evaluated using multiple two-way analyses of variance (shoulder x plane) with repeated measures. Results indicated no statistically significant differences between the surgical or nonsurgical shoulders for either concentric (p = .063-.247) or eccentric (p = .460-.840) modes, regardless of test plane. No statistically significant differences were observed eccentrically between test planes (p = .06-.470), but the scapular plane produced significantly higher (p = .005) peak torques concentrically. Generally, the external rotators were 53.0% (concentrically) and 63.0% (eccentrically) of the internal rotator strength for either shoulder. Clinically, concentric and eccentric testing of the postoperative shoulder patient can occur in either the scapular or the neutral plane. However, the scapular plane may be preferred since it is more functionally relevant and less injurious to the rotator cuff. A full, functional recovery may be expected for the rotator cuff repair patient.

  16. Isokinetic evaluation of trunk muscles.

    PubMed

    Langrana, N A; Lee, C K

    1984-03-01

    The purpose of this study is to identify those individuals at risk who have weak trunk muscles and are prone to back pain. The overall thrust of this research is to develop a quantitative method to assess dynamic strength of the trunk muscles. Two unique isokinetic strength testing units in sitting and standing postures have been designed. Three groups of volunteers were tested at different times and places. Quantitative measurements of the maximum strength, fatigue behavior of the abdominal and paraspinal muscles, maximum strength in different age groups and the role of the iliopsoas muscle have been performed. The study shows that women have lower maximum strength but equal or better fatigue endurance than men. There is a significant change in maximum strength with age. The maximum abdominal strength change with age showed a bimodal distribution. The iliopsoas muscle approximately doubled the maximum back strength in flexion. The test in the sitting posture was tolerated better than the test in the standing posture. Isokinetic back strength testing in the sitting posture was found to be effective and safe.

  17. Isokinetic strength of collegiate baseball pitchers during a season.

    PubMed

    Wilkin, Linda D; Haddock, Bryan L

    2006-11-01

    Pitching is suggested to expose the arm to physical stress that may lead to a decrease in strength. The purpose of this study was to examine the isokinetic internal and external rotational shoulder strength of Division II pitchers preseason, midseason, and postseason. The 9 pitchers were 23 +/- 0.67 years of age and weighed 91.2 +/- 3.14 kg. Each subject was evaluated utilizing a Biodex Isokinetic Dynamometer. Isokinetic internal and external concentric strength was assessed at 90 degrees of shoulder abduction and 90 degrees of elbow flexion at 300 and 450 degrees .s(-1) at each time point. A repeated-measures analysis of variance statistical analysis was performed using SPSS software. All data are reported as mean +/- SEM. Mean internal peak torques at 300 and 450 degrees .s(-1) preseason, midseason, and postseason were 50.66 +/- 2.27, 49.70 +/- 2.54, and 51.70 +/- 2.94 N.m and 37.14 +/- 2.54, 37.36 +/- 2.74, and 38.26 +/- 2.50 N.m, respectively. Mean external peak torques at 300 and 450 degrees .s(-1) preseason, midseason, and postseason were 30.16 +/- 1.69, 29.50 +/- 2.22, and 29.79 +/- 2.08 N.m and 17.68 +/- 2.15, 16.89 +/- 2.46, and 18.20 +/- 2.35 N.m, respectively. There were no differences in isokinetic internal or external concentric shoulder rotational mean peak torque of Division II pitchers at any speed tested or time point examined.

  18. Gravitational moment correction in isokinetic dynamometry using anthropometric data.

    PubMed

    Kellis, E; Baltzopoulos, V

    1996-07-01

    The purpose of this study was to compare different methods of gravity correction in isokinetic dynamometry. The gravitational moment of the left leg-foot segment of 25 males was measured on a Biodex dynamometer at 30 degrees of knee flexion statically, and as the segment was passively falling from 0 degree to 90 degrees with a constant velocity of 0.035 rad.s-1. The tests were performed in a supine and a seated position. The gravitational moments were also estimated from anthropometric data and directly, using a reaction board method that was considered as the criterion measurement. Furthermore, the isokinetic maximum moment output of the knee flexors and extensors was measured and corrected for gravity using the above methods at angular velocities of 0.52 rad.s-1 and 2.62 rad.s-1 during eccentric, and at 0.52 rad.s-1, 2.62 rad.s-1, and 4.71 rad.s-1 during concentric activations. One-way repeated-measures analysis of variance tests revealed significant differences (P < 0.05) between the gravitational moments obtained on the isokinetic dynamometer and those estimated from anthropometric data or by the reaction board method. The maximum extensor and flexor moments were significantly different, corrected using the gravity correction methods on the dynamometer relative to the anthropometric model or the reaction board (P < 0.05). These results suggest that the determination of gravitational moments based on anthropometric data is more accurate than current gravity correction methods. This new proposed method should be implemented in isokinetic dynamometry applications.

  19. Mechanomyographic responses for the biceps brachii are unable to track the declines in peak torque during 25, 50, 75, and 100 fatiguing isokinetic muscle actions.

    PubMed

    Stock, Matt S; Beck, Travis W; DeFreitas, Jason M; Ye, Xin

    2013-12-01

    This study examined the peak torque and mechanomyographic (MMG) amplitude and mean frequency (MNF) responses during fatiguing isokinetic muscle actions. On four separate occasions, twenty men (mean ± SD age = 23 ± 3 years) performed 25, 50, 75, and 100 repeated maximal concentric isokinetic muscle actions of the dominant forearm flexors. During each muscle action, the MMG signal was detected from the biceps brachii with an accelerometer. The data were examined with linear regression and one-way repeated measures analyses of variance. The results indicated that the mean percent decline in peak torque value for the 25 repetition trial (25.6%) was significantly less than that for the 50 repetition trial (45.2%). Furthermore, the mean linear slope coefficient for the peak torque versus repetition number relationship for the 50 repetition trial was significantly less than that for the 100 repetition trial. There were no mean differences among the trials for the linear slope coefficients and y-intercepts for the MMG amplitude and MNF versus repetition number relationships. When detected with an accelerometer, the linear slope coefficients and y-intercepts for the MMG amplitude and MNF versus repetition number relationships were not sensitive enough to track the decline in muscle function during fatigue.

  20. Effect of isokinetic training on shoulder impingement.

    PubMed

    Wang, T L; Fu, B M; Ngai, G; Yung, P

    2014-01-31

    The aim of this study was to review the literature evaluating the effect of isokinetic training in patients suffering from shoulder impingement syndrome (SIS). Studies published up to March 2011 were located from the Pubmed, Scopus, Lilacs, Physiotherapy Evidence Database, and Cochrane Library databases using "isokinetic", "shoulder", and "impingement" as key words. Referenced studies were also checked. Studies were included if isokinetic training was employed as at least one of the treatments in the therapeutic program to treat shoulder impingement or other shoulder pathologies leading to impingement-related pain. All eligible studies described the level of evidence, patient characteristics, interventions, outcome evaluation, results, complications, and return to work. There were 2 randomized control trials (RCTs) and 4 studies with level 4 evidence that met the inclusion criteria. All of the studies included showed a statistically or clinically significant outcome after isokinetic training. However, most of the studies could not identify the isolated effect of isokinetic training. There was not enough evidence to support or refute the effectiveness of isokinetic training for SIS. This result does not reflect a true lack of effect, but rather a lack of RCTs. A consensus definition of the different types and stages of SIS is urgently needed. More RCTs are also essential to clarify the value of this technique. The homogeneity of treatment interventions, study populations, and outcome measures should be prioritized. Further studies are also needed to clarify the differences in isokinetic data across different types and stages of shoulder impingement.

  1. Selective hypertrophy of the quadriceps musculature after 14 weeks of isokinetic and conventional resistance training.

    PubMed

    Matta, Thiago Torres; Nascimento, Francisco Xavier; Trajano, Gabriel S; Simão, Roberto; Willardson, Jeffrey Michael; Oliveira, Liliam Fernandes

    2017-03-01

    One of the fundamental adaptations observed with resistance training (RT) is muscle hypertrophy. Conventional and isokinetic machines provide different forms of mechanical stress, and it is possible that these two training modes could promote differing degrees of hypertrophic adaptations. There is a lack of data comparing the selective hypertrophy of the quadriceps musculature after training with a conventional knee extension machine versus an isokinetic machine. The purpose of this study was to evaluate the selective hypertrophy of the quadriceps musculature and knee extension maximal isometric torque after 14 weeks of conventional versus isokinetic RT. Thirty-five men were assigned to three groups: control group and training groups (conventional and isokinetic) performed three sets of unilateral knee extensions per session with a progressive loading scheme twice a week. Prior to and following the intervention, maximal isometric knee extensor torque was measured using an isokinetic dynamometer, and muscle thickness (MT) of quadriceps femoris muscles was assessed via ultrasound. The results indicated non-uniform changes in MT between the muscles that comprise the quadriceps femoris group. For the conventional group, significantly greater increases in rectus femoris thickness were evident versus all other quadriceps muscles (14%). For the isokinetic group, increases in RF thickness (11%) were significantly greater in comparison with the vastus intermedius only. Although the muscle thickness did not increase for all the quadriceps femoris muscles, the relative rectus femoris adaptation suggested a selective hypertrophy favouring this portion.

  2. INTERSESSION RELIABILITY OF UPPER EXTREMITY ISOKINETIC PUSH-PULL TESTING.

    PubMed

    Riemann, Bryan L; Davis, Sarah E; Huet, Kevin; Davies, George J

    2016-02-01

    Based on the frequency pushing and pulling patterns are used in functional activities, there is a need to establish an objective method of quantifying the muscle performance characteristics associated with these motions, particularly during the later stages of rehabilitation as criteria for discharge. While isokinetic assessment offers an approach to quantifying muscle performance, little is known about closed kinetic chain (CKC) isokinetic testing of the upper extremity (UE). To determine the intersession reliability of isokinetic upper extremity measurement of pushing and pulling peak force and average power at slow (0.24 m/s), medium (0.43 m/s) and fast (0.61 m/s) velocities in healthy young adults. The secondary purpose was to compare pushing and pulling peak force (PF) and average power (AP) between the upper extremity limbs (dominant, non-dominant) across the three velocities. Twenty-four physically active men and women completed a test-retest (>96 hours) protocol in order to establish isokinetic UE CKC reliability of PF and AP during five maximal push and pull repetitions at three velocities. Both limb and speed orders were randomized between subjects. High test-retest relative reliability using intraclass correlation coefficients (ICC2, 1) were revealed for PF (.91-.97) and AP (.85-.95) across velocities, limbs and directions. PF typical error (% coefficient of variation) ranged from 6.1% to 11.3% while AP ranged from 9.9% to 26.7%. PF decreased significantly (p < .05) as velocity increased whereas AP increased as velocity increased. PF and AP during pushing were significantly greater than pulling at all velocities, however the push-pull differences in PF became less as velocity increased. There were no significant differences identified between the dominant and nondominant limbs. Isokinetically derived UE CKC push-pull PF and AP are reliable measures. The lack of limb differences in healthy normal participants suggests that clinicians can

  3. The effects of motor learning on clinical isokinetic performance of postmenopausal women.

    PubMed

    Brech, Guilherme Carlos; Ciolac, Emmanuel Gomes; Secchi, Leonardo Luiz Barretti; Alonso, Angélica Castilho; Greve, Júlia Maria D'Andréa

    2011-12-01

    To analyze the effects of motor learning on knee extension-flexion isokinetic performance during clinical isokinetic evaluation of postmenopausal women. One-hundred and twenty postmenopausal women (60.3±3.2 years; BMI=27.6±4.7 kg/m(2)) without knee pain or injury and that never underwent isokinetic testing, were submitted to two bilateral knee extension-flexion (concentric-concentric) isokinetic evaluation (5 repetitions) at 60°/s (Biodex™ Multi-Joint System 3 dynamometer). The tests were first performed in the dominant leg, with a 1-min recovery between them, and after a standardized warm-up that included 3 submaximal isokinetic repetitions. The same procedure was repeated in the non-dominant leg. Peak torque (PTQ) was adjusted for body weight (PTQ/BW), total work (TW), coefficient of variation (CV) and agonist/antagonist (agon/antag) ratio was compared between tests. Subjects showed greater levels (P<0.001) of PTQ, PTQ/BW and TW, and lower CV levels (P<0.01) in test 2 of both legs. Agon/antag ratio did not change significantly between tests. PTQ, PTQ/BW, TW and CV improved in the second knee extension flexion isokinetic testing of postmenopausal women. The results suggests that performing two tests, even with a short period of recovery between them, could be considered for reducing motor learning effects on clinical isokinetic evaluation of knee joint in postmenopausal women. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  4. Isokinetic Strength and Endurance Tests used Pre- and Post-Spaceflight: Test-Retest Reliability

    NASA Technical Reports Server (NTRS)

    Laughlin, Mitzi S.; Lee, Stuart M. C.; Loehr, James A.; Amonette, William E.

    2009-01-01

    To assess changes in muscular strength and endurance after microgravity exposure, NASA measures isokinetic strength and endurance across multiple sessions before and after long-duration space flight. Accurate interpretation of pre- and post-flight measures depends upon the reliability of each measure. The purpose of this study was to evaluate the test-retest reliability of the NASA International Space Station (ISS) isokinetic protocol. Twenty-four healthy subjects (12 M/12 F, 32.0 +/- 5.6 years) volunteered to participate. Isokinetic knee, ankle, and trunk flexion and extension strength as well as endurance of the knee flexors and extensors were measured using a Cybex NORM isokinetic dynamometer. The first weekly session was considered a familiarization session. Data were collected and analyzed for weeks 2-4. Repeated measures analysis of variance (alpha=0.05) was used to identify weekly differences in isokinetic measures. Test-retest reliability was evaluated by intraclass correlation coefficients (ICC) (3,1). No significant differences were found between weeks in any of the strength measures and the reliability of the strength measures were all considered excellent (ICC greater than 0.9), except for concentric ankle dorsi-flexion (ICC=0.67). Although a significant difference was noted in weekly endurance measures of knee extension (p less than 0.01), the reliability of endurance measure by week were considered excellent for knee flexion (ICC=0.97) and knee extension (ICC=0.96). Except for concentric ankle dorsi-flexion, the isokinetic strength and endurance measures are highly reliable when following the NASA ISS protocol. This protocol should allow accurate interpretation isokinetic data even with a small number of crew members.

  5. Effects of Motor Learning on Clinical Isokinetic Test Performance in Knee Osteoarthritis Patients.

    PubMed

    Rodrigues-da-Silva, José Messias; de Rezende, Márcia Uchoa; Spada, Tânia Carvalho; da Silva Francisco, Lucila; Greve, Júlia Maria D'Andréa; Ciolac, Emmanuel Gomes

    2017-04-01

    To analyze the effects of motor learning on knee extension-flexion isokinetic performance in knee osteoarthritis patients. One hundred and thirty-six middle-aged and older sedentary individuals (111 women, 64.3±9.9 years) with knee osteoarthritis (130 patients with bilateral) and who had never performed isokinetic testing underwent two bilateral knee extension-flexion (concentric-concentric) isokinetic evaluations (5 repetitions) at 60°/sec. The tests were first performed on the dominant leg with 2 min of recovery between test, and following a standardized warm-up that included 3 submaximal isokinetic repetitions. The same procedure was repeated on the non-dominant leg. The peak torque, peak torque adjusted for the body weight, total work, coefficient of variation and agonist/antagonist ratio were compared between tests. Patients showed significant improvements in test 2 compared to test 1, including higher levels of peak torque, peak torque adjusted for body weight and total work, as well as lower coefficients of variation. The agonist/antagonist relationship did not significantly change between tests. No significant differences were found between the right and left legs for all variables. The results suggest that performing two tests with a short recovery (2 min) between them could be used to reduce motor learning effects on clinical isokinetic testing of the knee joint in knee osteoarthritis patients.

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

    PubMed Central

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

    2003-01-01

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

  7. Effects of Motor Learning on Clinical Isokinetic Test Performance in Knee Osteoarthritis Patients

    PubMed Central

    Rodrigues-da-Silva, José Messias; de Rezende, Márcia Uchoa; Spada, Tânia Carvalho; da Silva Francisco, Lucila; Greve, Júlia Maria D'Andréa; Ciolac, Emmanuel Gomes

    2017-01-01

    OBJECTIVES: To analyze the effects of motor learning on knee extension-flexion isokinetic performance in knee osteoarthritis patients. METHODS: One hundred and thirty-six middle-aged and older sedentary individuals (111 women, 64.3±9.9 years) with knee osteoarthritis (130 patients with bilateral) and who had never performed isokinetic testing underwent two bilateral knee extension-flexion (concentric-concentric) isokinetic evaluations (5 repetitions) at 60°/sec. The tests were first performed on the dominant leg with 2 min of recovery between test, and following a standardized warm-up that included 3 submaximal isokinetic repetitions. The same procedure was repeated on the non-dominant leg. The peak torque, peak torque adjusted for the body weight, total work, coefficient of variation and agonist/antagonist ratio were compared between tests. RESULTS: Patients showed significant improvements in test 2 compared to test 1, including higher levels of peak torque, peak torque adjusted for body weight and total work, as well as lower coefficients of variation. The agonist/antagonist relationship did not significantly change between tests. No significant differences were found between the right and left legs for all variables. CONCLUSION: The results suggest that performing two tests with a short recovery (2 min) between them could be used to reduce motor learning effects on clinical isokinetic testing of the knee joint in knee osteoarthritis patients. PMID:28492718

  8. Reliability of knee extension and flexion measurements using the Con-Trex isokinetic dynamometer.

    PubMed

    Maffiuletti, Nicola A; Bizzini, Mario; Desbrosses, Kevin; Babault, Nicolas; Munzinger, Urs

    2007-11-01

    The aim of this study was to evaluate the reliability of isokinetic and isometric assessments of the knee extensor and the flexor muscle function using the Con-Trex isokinetic dynamometer. Thirty healthy subjects (15 males, 15 females) were tested and retested 7 days later for maximal strength (isokinetic peak torque, work, power and angle of peak torque as well as isometric maximal voluntary contraction torque and rate of torque development) and fatigue (per cent loss and linear slope of torque and work across a series of 20 contractions). For both the knee extensor and the flexor muscle groups, all strength data - except angle of peak torque - demonstrated moderate-to-high reliability, with intraclass correlation coefficients (ICC) higher than 0.86. The highest reliability was observed for concentric peak torque of the knee extensor muscles (ICC = 0.99). Test-retest reliability of fatigue variables was moderate for the knee extensor (ICC range 0.84-0.89) and insufficient-to-moderate for the knee flexor muscles (ICC range 0.78-0.81). The more reliable index of muscle fatigue was the linear slope of the decline in work output. These findings establish the reliability of isokinetic and isometric measurements using the Con-Trex machine.

  9. Identification of cardiac repercussions after intense and prolonged concentric isokinetic exercise in young sedentary people.

    PubMed

    Le Goff, Caroline; Kaux, Jean-François; Couffignal, Vincent; Coubard, Romain; Mélon, Pierre; Cavalier, Etienne; Croisier, Jean-Louis

    2015-09-01

    Cardiopathies are the world's leading cause of mortality and morbidity. Although rare, cardiovascular accidents can occur during intense and infrequent sporting activity, particularly among those who are unaware of their heart condition. The development of cardiospecific biochemical markers has led to a reconsideration of the role of biology in the diagnosis of cardiovascular illnesses. The aim of this study therefore was, through the use of cardiac biomarker assays, to highlight the impact of sustained physical effort in the form of intense and prolonged concentric isokinetic exercise and to research potential cardiovascular risks. Eighteen subjects participated in a maximal concentric isokinetic exercise involving 30 knee flexion-extensions for each leg. Five blood tests were taken to study the kinetics of the cardiac biomarkers. Haemodynamic parameters were measured continuously using a Portapres, and respiratory parameters were measured using a Sensormedics Vmax 29C. The results showed significant increases in the creatine kinase, myoglobin, homocysteine and haemoglobin cardiac markers. Evolutionary trends were also observed for the following biomarkers: NT-proBNP, myeloperoxydase and C-reactive protein. All the physiological parameters measured presented statistically significant changes. Isokinetic effort leads to the release of cardiac markers in the blood, but these do not exceed the reference values in healthy subjects. Maximal concentric isokinetic exercise does not, therefore, lead to an increased risk of cardiovascular pathologies. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  10. The effects of concentric versus eccentric isokinetic strength training of the rotator cuff in the plane of the scapula at various speeds.

    PubMed

    Bast, S C; Vangsness, C T; Takemura, J; Folkins, E; Landel, R

    1998-01-01

    This study compares the effects of three modes of isokinetic resistance training at the shoulder--concentric, eccentric, and a combination of both concentric and eccentric, with a group that received no training at all. Twenty-eight healthy volunteers (male and females), 18 to 36 years of age, with no history of shoulder pathology, were randomly assigned to one of four groups; concentric training, eccentric training, a combination of both concentric and eccentric training, or control (no training). Testing and training of the dominant shoulder was performed on an isokinetic dynamometer. All subjects were pretested and post-tested both concentrically and eccentrically for humeral internal/external rotation and abduction at speeds of 60 degrees/sec and 120 degrees/sec. Each training session consisted of a total of twelve sets of ten maximal repetitions, and was repeated three times a week for four weeks. The absolute and percent difference in peak force and peak torque for each group between the pretest and post-test was calculated for each combination of position, mode, and speed. A significant difference between the concentric/eccentric group and the eccentric group was found for abduction (p < 0.05). The eccentric group showed a significantly greater increase from the pretest to post-test for absolute differences in peak force and peak torque compared to the concentric/eccentric group (p < 0.05).

  11. 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.

  12. The influence of acute hypoxic exposure on isokinetic muscle force production.

    PubMed

    Ivamoto, Rafael Kenji; Nakamoto, Fernanda Patti; Vancini, Rodrigo Luiz; Benedito-Silva, Ana Amélia; de Lira, Claudio Andre Barbosa; Andrade, Marília Dos Santos

    2014-01-01

    To investigated whether an acute hypoxic stimulus affects muscle strength development assessed by isokinetic dynamometry during maximal knee extension. A total of 15 healthy young men participated in this study (61.9 ± 6.1 kg; 1.72 ± 0.08 m; 20.9 ± 2.6 years). We evaluated knee extension and flexion isokinetic dynamometer performance in normoxic and hypoxic conditions. The analyzed parameters, for concentric contraction, were peak torque and total work measured at 1.05 and 5.23 rad/s; and fatigue index measured at 5.23 rad/s. During isokinetic testing, heart rate and oxygen saturation (SpO2) were monitored. Hypoxic conditions (3,600 m) were simulated, via a mixing chamber, with the dilution being constantly controlled by a PO2 probe. Test reproducibility results (test-retest) for all isokinetic knee parameters were classified as moderate to almost perfect (ICC = 0.694 to 0.932). SpO2 was 88.4 ± 3.4% in the hypoxic condition and 97.1 ± 0.7% in the normoxic condition (p = 0.000, effect size = 0.87). Heart rate was not significantly different between normoxic and hypoxic conditions at the end of the test. There were no significant differences in isokinetic variables evaluated for the extensor and flexor muscles at concentric contraction between the normoxic and hypoxic conditions. Our findings indicate that reduced arterial oxygenation per se has no effect on the muscular isokinetic strength of the knee extensors.

  13. Relationship between performances of 10-time-repeated sit-to-stand and maximal walking tests in non-disabled older women.

    PubMed

    Yanagawa, Naoko; Shimomitsu, Teruichi; Kawanishi, Masashi; Fukunaga, Tetsuo; Kanehisa, Hiroaki

    2016-06-27

    Sit-to-stand (STS) test is extensively used to assess the functionality of the lower body in elderly people. This study aimed to examine how the score of STS can be associated with that of maximal walking (MW) tests through a cross-sectional as well as longitudinal analysis for non-disabled older women. Times taken for a 10-time-repeated STS (STS time) and 5-m MW (MW time) were determined before (pre) and after (post) a 3-month body mass-based exercise program in 154 non-disabled women aged 60 to 79 years. In addition to the time scores, STS and MW power indexes (STS-PI and MW-PI, respectively) were calculated using the following equations: STS-PI = (body height - 0.4) × body mass × 10/STS time and MW-PI = body mass × 5/MW time. At pre- and post-intervention, STS-PI was significantly correlated to MW-PI, with higher correlation coefficients (r = 0.545-0.567, P < 0.0001) than those between the two time scores (r = 0.271-0.309, P < 0.001). The intervention significantly improved STS-time (13.6 ± 3.2 s at pre to 9.4 ± 1.8 s at post, P < 0.0001), MW time (2.4 ± 0.3 s to 2.2 ± 0.3 s, P < 0.0001), STS-PI (46.5 ± 12.5 to 65.7 ± 12.7, P < 0.0001), and MW-PI (112.1 ± 20.2 to 124.2 ± 24.4, P < 0.0001). There were significant correlations between the changes of STS and MW times (r = 0.281, P < 0.001) and between those of STS-PI and MW-PI (r = 0.366, P < 0.0001). In elderly women, the performance of sit-to-stand task and its training-induced gain are associated with those of the maximal walking task. In addition, the current results indicated that translation of the performance scores of the sit-to-stand and maximal walking tasks to power indexes may be a useful approach for examining the association between the two tasks.

  14. Agonist muscle activity and antagonist muscle co-activity levels during standardized isotonic and isokinetic knee extensions.

    PubMed

    Remaud, Anthony; Cornu, Christophe; Guével, Arnaud

    2009-06-01

    This study aimed to analyze the effects of the contraction mode (isotonic vs. isokinetic concentric conditions), the joint angle and the investigated muscle on agonist muscle activity and antagonist muscle co-activity during standardized knee extensions. Twelve healthy adult subjects performed three sets of isotonic knee extensions at 40% of their maximal voluntary isometric torque followed by three sets of maximal isokinetic knee extensions on an isokinetic dynamometer. For each set, the mean angular velocity and the total external amount of work performed were standardized during the two contraction modes. Surface electromyographic activity of vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), semitendinosus (ST) and biceps femoris (BF) muscles was recorded. Root mean square values were then calculated for each 10 degrees between 85 degrees and 45 degrees of knee extension (0 degrees =horizontal position). Results show that agonist muscle activity and antagonist muscle co-activity levels are significantly greater in isotonic mode compared to isokinetic mode. Quadriceps activity and hamstrings co-activity are significantly lower at knee extended position in both contraction modes. Considering agonist muscles, VL reveals a specific pattern of activity compared to VM and RF; whereas considering hamstring muscles, BF shows a significantly higher co-activity than ST in both contraction modes. Results of this study confirmed our hypothesis that higher quadriceps activity is required during isotonic movements compared to isokinetic movements leading to a higher hamstrings co-activity.

  15. Test-retest reliability of lower limb isokinetic endurance in COPD: A comparison of angular velocities.

    PubMed

    Ribeiro, Fernanda; Lépine, Pierre-Alexis; Garceau-Bolduc, Corine; Coats, Valérie; Allard, Étienne; Maltais, François; Saey, Didier

    2015-01-01

    The purpose of this study was to determine and compare the test-retest reliability of quadriceps isokinetic endurance testing at two knee angular velocities in patients with chronic obstructive pulmonary disease (COPD). After one familiarization session, 14 patients with moderate to severe COPD (mean age 65±4 years; forced expiratory volume in 1 second (FEV1) 55%±18% predicted) performed two quadriceps isokinetic endurance tests on two separate occasions within a 5-7-day interval. Quadriceps isokinetic endurance tests consisted of 30 maximal knee extensions at angular velocities of 90° and 180° per second, performed in random order. Test-retest reliability was assessed for peak torque, muscle endurance, work slope, work fatigue index, and changes in FEV1 for dyspnea and leg fatigue from rest to the end of the test. The intraclass correlation coefficient, minimal detectable change, and limits of agreement were calculated. High test-retest reliability was identified for peak torque and muscle total work at both velocities. Work fatigue index was considered reliable at 90° per second but not at 180° per second. A lower reliability was identified for dyspnea and leg fatigue scores at both angular velocities. Despite a limited sample size, our findings support the use of a 30-maximal repetition isokinetic muscle testing procedure at angular velocities of 90° and 180° per second in patients with moderate to severe COPD. Endurance measurement (total isokinetic work) at 90° per second was highly reliable, with a minimal detectable change at the 95% confidence level of 10%. Peak torque and fatigue index could also be assessed reliably at 90° per second. Evaluation of dyspnea and leg fatigue using the modified Borg scale of perceived exertion was poorly reliable and its clinical usefulness is questionable. These results should be useful in the design and interpretation of future interventions aimed at improving muscle endurance in COPD.

  16. Test-retest reliability of lower limb isokinetic endurance in COPD: A comparison of angular velocities

    PubMed Central

    Ribeiro, Fernanda; Lépine, Pierre-Alexis; Garceau-Bolduc, Corine; Coats, Valérie; Allard, Étienne; Maltais, François; Saey, Didier

    2015-01-01

    Background The purpose of this study was to determine and compare the test-retest reliability of quadriceps isokinetic endurance testing at two knee angular velocities in patients with chronic obstructive pulmonary disease (COPD). Methods After one familiarization session, 14 patients with moderate to severe COPD (mean age 65±4 years; forced expiratory volume in 1 second (FEV1) 55%±18% predicted) performed two quadriceps isokinetic endurance tests on two separate occasions within a 5–7-day interval. Quadriceps isokinetic endurance tests consisted of 30 maximal knee extensions at angular velocities of 90° and 180° per second, performed in random order. Test-retest reliability was assessed for peak torque, muscle endurance, work slope, work fatigue index, and changes in FEV1 for dyspnea and leg fatigue from rest to the end of the test. The intraclass correlation coefficient, minimal detectable change, and limits of agreement were calculated. Results High test-retest reliability was identified for peak torque and muscle total work at both velocities. Work fatigue index was considered reliable at 90° per second but not at 180° per second. A lower reliability was identified for dyspnea and leg fatigue scores at both angular velocities. Conclusion Despite a limited sample size, our findings support the use of a 30-maximal repetition isokinetic muscle testing procedure at angular velocities of 90° and 180° per second in patients with moderate to severe COPD. Endurance measurement (total isokinetic work) at 90° per second was highly reliable, with a minimal detectable change at the 95% confidence level of 10%. Peak torque and fatigue index could also be assessed reliably at 90° per second. Evaluation of dyspnea and leg fatigue using the modified Borg scale of perceived exertion was poorly reliable and its clinical usefulness is questionable. These results should be useful in the design and interpretation of future interventions aimed at improving muscle

  17. Assessment of isokinetic muscle function in Korea male volleyball athletes

    PubMed Central

    Kim, Chang-Gyun; Jeoung, Bog Ja

    2016-01-01

    Volleyball players performed numerous repetitions of spike actions, which uses and requires strong and explosive force, and control of the muscles of the shoulder, lower back, and legs. Muscle imbalance is one of the main causes of sport injuries. The purpose of this study was to assess isokinetic muscle functions in male volleyball players. We thus aim to accurately evaluate their muscle functions, and identify the best training strategy to achieve optimal muscle strength balance in future training programs. The participants in this study consisted of 14 male volleyball players. Muscle strength was measured using the isokinetic dynamometer. Muscle strength was evaluated in terms of peak torque and average power, calculated from five repeated measurements at an angular speed of 60°/sec. Three players who were left attackers showed shoulder imbalance, four players showed trunk joint imbalance, nine players had knee joint of extension/flexion imbalance and four players showed left/right imbalance. The results showed that the number of volleyball players with differences between the strength of the bilateral knee muscles, and between the strength of the hamstrings and quadriceps muscles was higher than the number of players with differences between the strength of the shoulder internal and external rotation muscles, and higher than the number of players with differences between the strength of the lower back extension and flexion muscles. PMID:27807521

  18. Isokinetic muscle testing for weak patients suffering from neuromuscular disorders: a reliability study.

    PubMed

    Tiffreau, Vincent; Ledoux, Isabelle; Eymard, Bruno; Thévenon, André; Hogrel, Jean-Yves

    2007-07-01

    Precise, sensitive muscle strength testing methods are needed to investigate muscle function in patients with neuromuscular disorders (NMD). Here, we describe an isokinetic knee flexor and extensor testing procedure using the Biodex 3's continuous passive motion (CPM) mode. The torque values recorded during passive isokinetic motion were subtracted from the torque values obtained for the same movement with maximal, concentric effort. The aims of the present study were to (i) evaluate the method's reliability in NMD patients presenting mild to severe muscle weakness and (ii) study the relationship between manual muscle testing (MMT) and isokinetic dynamometry. The fifteen participating patients were tested twice; the respective intraclass correlation coefficients (ICCs) for the two sessions ranged from 0.91 to 0.99 for the peak torque, work and power and from 0.50 to 0.90 for the angle at peak torque. The Spearman rho correlation coefficients comparing isokinetic values and MMT values ranged from 0.67 to 0.74 (p<0.01). This reliable, dynamic method appears to be of great value in NMD evaluation when sensitive strength measurement at the knee is required.

  19. Kinesio Taping Does Not Alter Quadriceps Isokinetic Strength and Power in Healthy Nonathletic Men: A Prospective Crossover Study

    PubMed Central

    Korman, Paweł; Straburzyńska-Lupa, Anna; Rutkowski, Radosław; Gruszczyński, Jakub; Lewandowski, Jacek; Straburzyński-Lupa, Marcin; Łochyński, Dawid

    2015-01-01

    Objectives. The effects of Kinesio Taping (KT) on muscular performance remain largely unclear. This study aimed to investigate the acute effects of KT on the maximum concentric and eccentric quadriceps isokinetic strength. Study Design. This is a single-blinded, placebo crossover, repeated measures study. Methods. Maximum isokinetic concentric/eccentric extension torque, work, and power were assessed by an isokinetic dynamometer without taping (NT) and with KT or placebo taping (PT) in 17 healthy young men. Repeated measures one-way analysis of variance (ANOVA) was used for statistical analyses. Results. Testing concentric contractions at 60°/s or 180°/s isokinetic speed, no significant differences in peak torque (Nm), total work (J), or mean power (W) were noted among the application modes under different conditions. Testing eccentric contractions at 30°/s or 60°/s isokinetic speed, no significant differences in mentioned parameters were noted, respectively. KT on the quadriceps neither decreased nor increased muscle strength in the participants. Conclusion. KT application onto the skin overlying the quadriceps muscle does not enhance the strength or power of knee extensors in healthy men. PMID:26819953

  20. Kinesio Taping Does Not Alter Quadriceps Isokinetic Strength and Power in Healthy Nonathletic Men: A Prospective Crossover Study.

    PubMed

    Korman, Paweł; Straburzyńska-Lupa, Anna; Rutkowski, Radosław; Gruszczyński, Jakub; Lewandowski, Jacek; Straburzyński-Lupa, Marcin; Łochyński, Dawid

    2015-01-01

    The effects of Kinesio Taping (KT) on muscular performance remain largely unclear. This study aimed to investigate the acute effects of KT on the maximum concentric and eccentric quadriceps isokinetic strength. This is a single-blinded, placebo crossover, repeated measures study. Maximum isokinetic concentric/eccentric extension torque, work, and power were assessed by an isokinetic dynamometer without taping (NT) and with KT or placebo taping (PT) in 17 healthy young men. Repeated measures one-way analysis of variance (ANOVA) was used for statistical analyses. Testing concentric contractions at 60°/s or 180°/s isokinetic speed, no significant differences in peak torque (Nm), total work (J), or mean power (W) were noted among the application modes under different conditions. Testing eccentric contractions at 30°/s or 60°/s isokinetic speed, no significant differences in mentioned parameters were noted, respectively. KT on the quadriceps neither decreased nor increased muscle strength in the participants. KT application onto the skin overlying the quadriceps muscle does not enhance the strength or power of knee extensors in healthy men.

  1. Repeated Bout Effect in Muscle-Specific Exercise Variations.

    PubMed

    Zourdos, Michael C; Henning, Paul C; Jo, Edward; Khamoui, Andy V; Lee, Sang-Rok; Park, Young-Min; Naimo, Marshall; Panton, Lynn B; Nosaka, Kazunori; Kim, Jeong-Su

    2015-08-01

    A single bout of unaccustomed exercise confers protective effect against muscle damage from a subsequent bout of similar activity, that is, repeated bout effect (RBE). It remains unknown whether varying muscle-specific exercise between sessions alters the magnitude of the RBE. This study examined the effects of muscle-specific exercise variation between consecutive sessions on the RBE. Twenty untrained males (21 ± 2 years) were assigned to one of 2 groups (n = 10 per group): (a) 2 sessions of incline curls, Fixed Exercise or (b) 1 session of incline curls followed by 1 session of preacher curls, Varied Exercise, with 7 days between sessions. Subjects performed 5 sets of 6 repetitions at ∼50% of maximal isometric elbow flexor strength during each session. Changes in maximal voluntary isometric and isokinetic torque, range of motion, muscle soreness, and serum creatine kinase were measured before, immediately after, and 24, 48, 72, and 96 hours after each exercise session, and the changes were compared between bouts and between groups. There were significant time effects (p < 0.05) for isometric maximal voluntary contraction, concentric maximal voluntary contraction, range of motion, and muscle soreness during sessions 1 and 2 with no between-group differences. Both groups demonstrated a significantly faster recovery of range of motion and soreness to baseline levels after session 2 compared with session 1. Overall, our findings suggest that incline curls conferred a protective effect during subsequent preacher curls in a similar way to repeating incline curls; therefore, the RBE was not exercise specific.

  2. Relationship between isokinetic concentric and eccentric contraction modes in the knee flexor and extensor muscle groups.

    PubMed

    Wu, Y; Li, R C; Maffulli, N; Chan, K M; Chan, J L

    1997-09-01

    We investigated whether in normal subjects isokinetic concentric and eccentric strength variables were related in order to have a better picture in relation to rehabilitation and possible injury prevention. We studied the relationship between isokinetic concentric and eccentric peak torque, total work, and average power of knee extension and knee flexion at 60 degrees/sec and 120 degrees/sec in 42 young Chinese adults (22 males, age = 27 +/- 6.9 years; 20 females, age = 24.9 +/- 5.05 years) using the Cybex 6000 isokinetic dynamometer. Repeated analysis of covariance was used to compare the means between concentric and eccentric variables adjusted by limb dominance, speed of testing, and the muscle groups tested. A highly significant correlation was found between all concentric and eccentric variables, with correlation coefficients (r) ranging from 0.67 to 0.93. All but two of the eccentric variables were significantly greater than the concentric variables. Concentric and eccentric knee flexion to knee extension (H:Q) ratios were poorly correlated, with r ranging from 0.359 to 0.645. Although there is an acceptably high correlation between isokinetic concentric and eccentric strength variables of knee flexion and extension in young healthy individuals, we recommend measuring concentric and eccentric strength to plan a proper rehabilitation program and to assess muscle groups in a given contraction mode.

  3. Effect of isokinetic resistance training under a condition of restricted blood flow with pressure.

    PubMed

    Sakuraba, Keishoku; Ishikawa, Takuji

    2009-09-01

    The purpose of the present study was to investigate the effect of isokinetic training under the condition of restricted blood flow with pressure. The subjects were 21 athletes at a university. They were classified into four training groups: group A (high speed under restricted blood flow condition with pressure); group B (low speed under restricted blood flow condition with pressure); group C (high speed without restricted blood flow condition); group D (low speed without restricted blood flow condition). The training session consisted of three sets of knee extension and flexion (repeated 10 times) using an isokinetic training machine (Biodex system 3). The training period was 4 weeks, with regular training sessions twice a week during this period. Before and after the training period, all of the subjects underwent measurements of quadriceps muscular strength of concentric contraction (CC) and eccentric contraction (EC) after isokinetic contraction as well as measurement of the thigh diameter. In addition, the group with restricted blood flow with pressure underwent magnetic resonance imaging (MRI). In regard to quadriceps muscular strength before and after training, there was a significant difference between groups A and C at many degrees of velocity. For the muscular volume measurements by MRI before and after training, no significant difference was seen in group A or group B. A significant increase was not seen even when comparing groups A and B. Isokinetic resistance training with restricted blood flow with pressure had an effect on muscular strength improvement.

  4. Effect of subject restraint and resistance pad placement on isokinetic knee flexor and extensor strength: implications for testing and rehabilitation.

    PubMed

    Otten, Roald; Whiteley, Rod; Mitchell, Tim

    2013-03-01

    In clinical practice, several subject restraint and resistance pad placement variations are used when an isokinetic knee flexion/extension test is performed. However, it is unknown if these variations affect the outcome measures. The aims of this study were to determine if these setup variations affect isokinetic outcomes and to establish the smallest detectable difference for these setup variations. Variation in isokinetic setup affects outcome measures. Cross-sectional repeated-measures crossover study. Ten recreationally active adult men were examined with isokinetic dynamometry on 4 separate days. In the first 3 days, fully strapped and trunk-unstrapped testing was conducted with the resistance pad placed distally on the shin. On days 1 and 3, the unstrapped condition was performed first, followed by the strapped condition. On day 4, the resistance pad was placed proximal on the shin (anterior cruciate ligament testing). There were no within-condition differences for days 1, 2, or 3 for the strapped and unstrapped conditions (P > 0.05). Between-condition comparisons were significant (eg, quadriceps peak torque, P < 0.001; hamstring peak torque, P = 0.043) for the strapped, unstrapped, and proximal resistance pad placement conditions. The strapped condition generally showed the largest torques, and the unstrapped, the least. The smallest detectable differences were relatively large (eg, quadriceps peak torque strapped = 20.6%). The greatest intraclass correlation values were found when strapped. Subject setup significantly influences isokinetic outcome measures at the knee. Since the strapped condition demonstrated the greatest repeatability, it is recommended. The smallest detectable differences were relatively high for all variables and should be considered in the interpretation of the effect size of interventions. Subject setup strapping must be considered when investigating test-retest values or when comparing subjects after isokinetic testing at the knee

  5. Isometric and isokinetic hip strength and agonist/antagonist ratios in symptomatic femoroacetabular impingement.

    PubMed

    Diamond, Laura E; Wrigley, Tim V; Hinman, Rana S; Hodges, Paul W; O'Donnell, John; Takla, Amir; Bennell, Kim L

    2016-09-01

    This study investigated isometric and isokinetic hip strength in individuals with and without symptomatic femoroacetabular impingement (FAI). The specific aims were to: (i) determine whether differences exist in isometric and isokinetic hip strength measures between groups; (ii) compare hip strength agonist/antagonist ratios between groups; and (iii) examine relationships between hip strength and self-reported measures of either hip pain or function in those with FAI. Cross-sectional. Fifteen individuals (11 males; 25±5 years) with symptomatic FAI (clinical examination and imaging (alpha angle >55° (cam FAI), and lateral centre edge angle >39° and/or positive crossover sign (combined FAI))) and 14 age- and sex-matched disease-free controls (no morphological FAI on magnetic resonance imaging) underwent strength testing. Maximal voluntary isometric contraction strength of hip muscle groups and isokinetic hip internal (IR) and external rotation (ER) strength (20°/s) were measured. Groups were compared with independent t-tests and Mann-Whitney U tests. Participants with FAI had 20% lower isometric abduction strength than controls (p=0.04). There were no significant differences in isometric strength for other muscle groups or peak isokinetic ER or IR strength. The ratio of isometric, but not isokinetic, ER/IR strength was significantly higher in the FAI group (p=0.01). There were no differences in ratios for other muscle groups. Angle of peak IR torque was the only feature correlated with symptoms. Individuals with symptomatic FAI demonstrate isometric hip abductor muscle weakness and strength imbalance in the hip rotators. Strength measurement, including agonist/antagonist ratios, may be relevant for clinical management of FAI. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  6. 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

  7. The Effects of Rest Interval on Quadriceps Torque During an Isokinetic Testing Protocol in Elderly

    PubMed Central

    Bottaro, Martim; Russo, André Faria; de Oliveira, Ricardo Jacó

    2005-01-01

    The purpose of this study was to compare three different intervals for a between sets rest period during a common isokinetic knee extension strength-testing protocol of twenty older Brazilian men (66.30 ± 3.92 yrs). The volunteers underwent unilateral knee extension (Biodex System 3) testing to determine their individual isokinetic peak torque at 60, 90, and 120°s-1. The contraction speeds and the rest periods between sets (30, 60 and 90 s) were randomly performed in three different days with a minimum rest period of 48 hours. Significant differences between and within sets were analyzed using a One Way Analysis of Variance (ANOVA) with repeated measures. Although, at angular velocity of 60°s-1 produced a higher peak torque, there were no significant differences in peak torque among any of the rest periods. Likewise, there were no significant differences between mean peak torque among all resting periods (30, 60 and 90s) at angular velocities of 90 and 120°s-1. The results showed that during a common isokinetic strength testing protocol a between set rest period of at least 30 s is sufficient for recovery before the next test set in older men. Key Points The assessment of muscular strength using isokinetics muscle contraction in older individuals is very important for exercise prescription and rehabilitation. The minimal time between intraset isokinetics knee extension assessment in older individuals need to be more investigated, however 30 s appear to besufficient time for strength recover. PMID:24453533

  8. Symptomatic and functional responses to concentric-eccentric isokinetic versus eccentric-only isotonic exercise.

    PubMed

    Parr, Jeffrey J; Yarrow, Joshua F; Garbo, Carolyn M; Borsa, Paul A

    2009-01-01

    Rehabilitation protocols involving eccentric resistance exercise performed with loading more than 100% concentric 1-repetition maximum are effective in increasing muscle function in both healthy and injured populations. The mode of eccentric exercise (isokinetic versus isotonic) may be an important factor in limiting symptoms of delayed-onset muscle soreness and in improving muscle function after training. To compare functional and symptomatic responses after an eccentric-only (ECC) isotonic exercise protocol and after a combined concentric-eccentric (CON-ECC) isokinetic exercise protocol matched for total exercise volume. Observational study. Controlled research laboratory. Twenty-four healthy, untrained, college-aged men (n = 12) and women (n = 12). Participants were randomly assigned to the ECC isotonic or CON-ECC isokinetic exercise group and performed a single bout of resistance exercise involving the elbow flexors. Measurements of elbow flexion and extension, isometric strength, and muscle point tenderness were obtained before exercise (baseline) and during follow-up sessions (days 2, 4, 7, and 14). Separate 1-way analyses of variance and repeated-measures analyses of variance were used to determine outcome differences. Tukey post hoc testing was performed when indicated. At baseline, no differences were present between groups for any measure. The ECC isotonic exercise protocol resulted in a 30% to 36% deficit in muscle strength, a 5% to 7% reduction in elbow flexion, and a 6% to 8% reduction in elbow extension at follow-up days 2 and 4 (P < .01). The CON-ECC isokinetic exercise protocol did not alter muscle strength or range of motion at any time when compared with baseline. Muscle point tenderness increased from baseline on days 2 and 4 in both groups (P < .05) but was not different between groups throughout the recovery period. Our results indicated more pronounced functional deficits occurred after a single bout of ECC isotonic exercise than with a CON

  9. Effect of isokinetic training on strength, functionality and proprioception in athletes with functional ankle instability.

    PubMed

    Sekir, Ufuk; Yildiz, Yavuz; Hazneci, Bulent; Ors, Fatih; Aydin, Taner

    2007-05-01

    The purpose of this study was to investigate the effects of isokinetic exercise on strength, joint position sense and functionality in recreational athletes with functional ankle instability (FAI). Strength, proprioception and balance of 24 recreational athletes with unilateral FAI were evaluated by using isokinetic muscle strength measurement, ankle joint position sense and one leg standing test. The functional ability was evaluated using five different tests. These were; single limb hopping course (SLHC), one legged and triple legged hop for distance (OLHD-TLHD), and six and cross six meter hop for time (SMHT-CSMHT). Isokinetic peak torque of the ankle invertor and evertor muscles were assessed eccentrically and concentrically at test speeds of 120 degrees /s. Isokinetic exercise protocol was carried out at an angular velocity of 120 degrees /s. The exercise session was repeated three times a week and lasted after 6 weeks. At baseline, concentric invertor strength was found to be significantly lower in the functionally unstable ankles compared to the opposite healthy ankles (p < 0.001). This difference was not present after executing the 6 weeks exercise sessions (p > 0.05). Ankle joint position sense in the injured ankles declined significantly from 2.35 +/- 1.16 to 1.33 +/- 0.62 degrees for 10 degrees of inversion angle (p < 0.001) and from 3.10 +/- 2.16 to 2.19 +/- 0.98 degrees for 20 degrees of inversion angle (p < 0.05) following the isokinetic exercise. One leg standing test score decreased significantly from 15.17 +/- 8.50 to 11.79 +/- 7.81 in the injured ankles (p < 0.001). Following the isokinetic exercise protocol, all of the worsened functional test scores in the injured ankles as compared to the opposite healthy ankles displayed a significant improvement (p < 0.01 for OLHD and CSMHT, p < 0.001 for SLHC, TLHD, and SMHT). These results substantiate the deficits of strength, proprioception, balance and functionality in recreational athletes with FAI. The

  10. Test-Retest Reliability of Isokinetic Knee Strength Measurements in Children Aged 8 to 10 Years.

    PubMed

    Fagher, Kristina; Fritzson, Annelie; Drake, Anna Maria

    Isokinetic dynamometry is a useful tool to objectively assess muscle strength of children and adults in athletic and rehabilitative settings. This study examined test-retest reliability of isokinetic knee strength measurements in children aged 8 to 10 years and defined limits for the minimum difference (MD) in strength that indicates a clinically important change. Isokinetic knee strength measurements (using the Biodex System 4) in children will provide reliable results. Descriptive laboratory study. In 22 healthy children, 5 maximal concentric (CON) knee extensor (KE) and knee flexor (KF) contractions at 2 angular velocities (60 deg/s and 180 deg/s) and 5 maximal eccentric (ECC) KE/KF contractions at 60 deg/s were assessed 7 days apart. The intraclass correlation coefficient (ICC2.1) was used to examine relative reliability, and the MD was calculated on the basis of standard error of measurement. ICCs for CON KE/KF peak torque measurements were fair to excellent (range, 0.49-0.81). The MD% values for CON KE and KF ranged from 31% to 37% at 60 deg/s and from 34% to 39% at 180 deg/s. ICCs in the ECC mode were good (range, 0.60-0.70), but associated MD% values were high (>50%). There was no systematic error for CON KE/KF and ECC KE strength measurements at 60 deg/s, but systematic error was found for all other measurements. The dynamometer provides a reliable analysis of isokinetic CON knee strength measurements at 60 deg/s in children aged 8 to 10 years. Measurements at 180 deg/s and in the ECC mode were not reliable, indicating a need for more familiarization prior to testing. The MD values may help clinicians to determine whether a change in knee strength is due to error or intervention.

  11. Electromyographic analysis of upper limb muscles during standardized isotonic and isokinetic robotic exercise of spastic elbow in patients with stroke.

    PubMed

    Sin, Minki; Kim, Won-Seok; Park, Daegeun; Min, Yu-Sun; Kim, Woo Jin; Cho, Kyujin; Paik, Nam-Jong

    2014-02-01

    Although it has been reported that strengthening exercise in stroke patients is beneficial for their motor recovery, there is little evidence about which exercise method is the better option. The purpose of this study was to compare isotonic and isokinetic exercise by surface electromyography (EMG) analysis using standardized methods. Nine stroke patients performed three sets of isotonic elbow extensions at 30% of their maximal voluntary isometric torque followed by three sets of maximal isokinetic elbow extensions with standardization of mean angular velocity and the total amount of work for each matched set in two strengthening modes. All exercises were done by using 1-DoF planner robot to regulate exact resistive torque and speed. Surface electromyographic activity of eight muscles in the hemiplegic shoulder and elbow was recorded. Normalized root mean square (RMS) values and co-contraction index (CCI) were used for the analysis. The isokinetic mode was shown to activate the agonists of elbow extension more efficiently than the isotonic mode (normalized RMS for pooled triceps: 96.0±17.0 (2nd), 87.8±14.4 (3rd) in isokinetic, 80.9±11.0 (2nd), 81.6±12.4 (3rd) in isotonic contraction, F[1,8]=11.168; P=0.010) without increasing the co-contraction of muscle pairs, implicating spasticity or synergy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Isokinetic muscle strength and hiking performance in elite sailors.

    PubMed

    Aagaard, P; Beyer, N; Simonsen, E B; Larsson, B; Magnusson, S P; Kjaer, M

    1998-06-01

    The aim of the present study was to describe the isokinetic strength profile and its relation to hiking performance in male (SM, n = 15) and female (SF, n = 6) elite sailors compared to a group of male control subjects (CM, n = 8) similar in age, anthropometry and level of fitness. Eccentric knee extension strength was higher in SM compared to CM (P < 0.01). Furthermore, SM were stronger during trunk extension (P < 0.05), but not during trunk flexion compared to CM. Overall muscle strength was lower in SF compared to SM (P < 0.01) and CM (P < 0.05), except for eccentric knee extension strength, where SF and CM did not differ (P > 0.05). Hiking performance correlated to maximal eccentric and isometric knee extensor strength in SF (rs = 0.83-0.88, P < 0.05) and in CM (rs = 0.73-0.77, P < 0.05) and to maximal eccentric knee extensor strength at high velocity in SM (rs = 0.46-0.54, P < 0.05). For a subgroup of hikers in SM (n = 8), hiking performance correlated to maximal isometric-eccentric knee extensor strength (rs = 0.67-0.74, P < 0.05), whereas no correlations emerged for the non-hikers (n = 7). Few correlations were observed between hiking performance and maximal concentric trunk flexor strength (rs = 0.69-0.92, P < 0.05). Unexpectedly, in SM correlations also were observed between hiking performance and maximal strength of the trunk extensors (rs = 0.46-0.53, hiker subgroup: rs = 0.64-0.67, P < 0.05). In conclusion, notably high levels of maximal eccentric knee extensor strength were observed for the male and female elite sailors examined in the present study. Furthermore, the present results suggest that hiking performance depends in part on maximal isometric-eccentric knee extensor strength. The maximal strength of the trunk extensors, which potentially stabilizes the lower back and spine, also seems to have some importance for the hiking performance of top-level sailors.

  13. [Sincerity of effort: isokinetic evaluation of knee extension].

    PubMed

    Colombo, R; Demaiti, G; Sartorio, F; Orlandini, D; Vercelli, S; Ferriero, G

    2008-01-01

    The aim of this study was to find a reliable method to evaluate the sincerity of the muscular maximal effort performed in a dynamometric isokinetic test of knee flexion-extension. The coefficient of variation of the peak torque (CV) and 3 new indices were analysed: (1) the average coefficient of variation calculated on the complete peak torque curve (CVM); (2) the slope of the regression line in an endurance test (PRR); (3) the correlation coefficient of the peak torques in the same endurance test (CCR). Twenty healthy subjects underwent assessment in two different trials, maximal (MX) and 50% submaximal (SMX), with 20 minutes of rest between trials. Each trial consisted of 4 tests, each of 3 repetitions, at angular speed of 30, 180, 30, and 180 degrees/s, respectively, and 1 test of 15 repetitions at 240 degrees/s. Our findings confirmed the ability of CV to detect a high percentage of sincere efforts: at 30 degrees/s Sensibility (Sns)=100% and Specificity (Spc)=70%; at 180 degrees/s Sns=75%, Spc=95%. The 3 new indices here proposed showed high characteristics of Sns and Spc, generally better than those of CV. CVM showed at 180 degrees/s Sns=90% and Spc=100%, while at 30 degrees/s Sns=90%, Spc=75%. PRR was the best index identifying all the efforts, except one (Sns=100%, Spc=95%). The CCR coefficient showed Sns and Spc values both of 90%.

  14. [Influence of testing position on lumbar isokinetic measurements].

    PubMed

    Cohen, P; Chantraine, A; Gobelet, C; Ziltener, J L

    2002-01-01

    The studies carried out on the lumbar spine, using an isokinetic type machine, showed the importance of the extensor muscles and the force they develop, compared with the flexor muscles. Both the sitting and standing positions were used without determining the better position. MAIN OBJECTIVE OF THE STUDY: To determine how the patients position influenced the performance of the muscles. We also studied a new parameter : the angle to maximal peak torque (APT). 17 healthy subjects and 19 suffering from low back pain were chosen. We perform the test in both positions for each subject. We compare in each group the peak torque of the extensor and flexor muscles on both positions and the angle of this torque. Low back pain subjects flexor/extensor ratio were 1.71 sitting and 1.56 standing. Healthy subjects showed normal ratio of 0.69 and 0.84. The position of the subject has no influence on the results in the low back pain subjects, and the sitting position is preferred. The angle of development of the maximal peak torque in both groups of muscles was very interesting, especially in the subjects suffering from low back pain and shines a new light on the different functions of the muscles of the low back pain suffering subjects and the healthy subjects. This angle (APT) is inversed in low back pain subjects who develop more torque for the extensors in extension of the spine.

  15. Evidence of circadian rhythm, oxygen regulation capacity, metabolic repeatability and positive correlations between forced and spontaneous maximal metabolic rates in lake sturgeon Acipenser fulvescens.

    PubMed

    Svendsen, Jon C; Genz, Janet; Anderson, W Gary; Stol, Jennifer A; Watkinson, Douglas A; Enders, Eva C

    2014-01-01

    Animal metabolic rate is variable and may be affected by endogenous and exogenous factors, but such relationships remain poorly understood in many primitive fishes, including members of the family Acipenseridae (sturgeons). Using juvenile lake sturgeon (Acipenser fulvescens), the objective of this study was to test four hypotheses: 1) A. fulvescens exhibits a circadian rhythm influencing metabolic rate and behaviour; 2) A. fulvescens has the capacity to regulate metabolic rate when exposed to environmental hypoxia; 3) measurements of forced maximum metabolic rate (MMR(F)) are repeatable in individual fish; and 4) MMR(F) correlates positively with spontaneous maximum metabolic rate (MMR(S)). Metabolic rates were measured using intermittent flow respirometry, and a standard chase protocol was employed to elicit MMR(F). Trials lasting 24 h were used to measure standard metabolic rate (SMR) and MMR(S). Repeatability and correlations between MMR(F) and MMR(S) were analyzed using residual body mass corrected values. Results revealed that A. fulvescens exhibit a circadian rhythm in metabolic rate, with metabolism peaking at dawn. SMR was unaffected by hypoxia (30% air saturation (O(2sat))), demonstrating oxygen regulation. In contrast, MMR(F) was affected by hypoxia and decreased across the range from 100% O(2sat) to 70% O(2sat). MMR(F) was repeatable in individual fish, and MMR(F) correlated positively with MMR(S), but the relationships between MMR(F) and MMR(S) were only revealed in fish exposed to hypoxia or 24 h constant light (i.e. environmental stressor). Our study provides evidence that the physiology of A. fulvescens is influenced by a circadian rhythm and suggests that A. fulvescens is an oxygen regulator, like most teleost fish. Finally, metabolic repeatability and positive correlations between MMR(F) and MMR(S) support the conjecture that MMR(F) represents a measure of organism performance that could be a target of natural selection.

  16. Evidence of Circadian Rhythm, Oxygen Regulation Capacity, Metabolic Repeatability and Positive Correlations between Forced and Spontaneous Maximal Metabolic Rates in Lake Sturgeon Acipenser fulvescens

    PubMed Central

    Svendsen, Jon C.; Genz, Janet; Anderson, W. Gary; Stol, Jennifer A.; Watkinson, Douglas A.; Enders, Eva C.

    2014-01-01

    Animal metabolic rate is variable and may be affected by endogenous and exogenous factors, but such relationships remain poorly understood in many primitive fishes, including members of the family Acipenseridae (sturgeons). Using juvenile lake sturgeon (Acipenser fulvescens), the objective of this study was to test four hypotheses: 1) A. fulvescens exhibits a circadian rhythm influencing metabolic rate and behaviour; 2) A. fulvescens has the capacity to regulate metabolic rate when exposed to environmental hypoxia; 3) measurements of forced maximum metabolic rate (MMRF) are repeatable in individual fish; and 4) MMRF correlates positively with spontaneous maximum metabolic rate (MMRS). Metabolic rates were measured using intermittent flow respirometry, and a standard chase protocol was employed to elicit MMRF. Trials lasting 24 h were used to measure standard metabolic rate (SMR) and MMRS. Repeatability and correlations between MMRF and MMRS were analyzed using residual body mass corrected values. Results revealed that A. fulvescens exhibit a circadian rhythm in metabolic rate, with metabolism peaking at dawn. SMR was unaffected by hypoxia (30% air saturation (O2sat)), demonstrating oxygen regulation. In contrast, MMRF was affected by hypoxia and decreased across the range from 100% O2sat to 70% O2sat. MMRF was repeatable in individual fish, and MMRF correlated positively with MMRS, but the relationships between MMRF and MMRS were only revealed in fish exposed to hypoxia or 24 h constant light (i.e. environmental stressor). Our study provides evidence that the physiology of A. fulvescens is influenced by a circadian rhythm and suggests that A. fulvescens is an oxygen regulator, like most teleost fish. Finally, metabolic repeatability and positive correlations between MMRF and MMRS support the conjecture that MMRF represents a measure of organism performance that could be a target of natural selection. PMID:24718688

  17. The Influence of Velocity Overshoot Movement Artifact on Isokinetic Knee Extension Tests

    PubMed Central

    Schwartz, Fabiano Peruzzo; Bottaro, Martim; Celes, Rodrigo Souza; Brown, Lee E.; Nascimento, Francisco Assis de Oliveira

    2010-01-01

    Exercise on an isokinetic device involves three distinct movement phases: acceleration, constant velocity, and deceleration. Inherent in these phases are unique occurrences that may confound test data and, thereby, test interpretation. Standard methods of data reduction like windowing and other techniques consist of removing the acceleration and deceleration phases in order to assure analysis under constant velocity conditions. However, none of these techniques adequately quantify the velocity overshoot (VO) movement artifact which is a result of the devices resistance imposed to the limb. This study tested the influence of VO on isokinetic data interpretation. A computational algorithm was developed to accurately identify each movement phase and to delineate the VO segment. Therefore, the VO was then treated as a fourth and independent phase. A total of sixteen healthy men (26.8 ± 4.7 yrs, 1.76 ± 0.05 m, and 79.2 ± 9.4 kg) performed two sets of ten maximal concentric extension repetitions of their dominant knee (at 60°·s-1 and 180°·s-1), on separate days and in a counterbalanced order, on a Biodex System 3 Pro dynamometer. All the phases of the isokinetic exercise were measured in terms of their biomechanical descriptors and according to the developed algorithm, the windowing method, and a data reduction technique that eliminates the first and last 10° of the total range of motion. Results showed significant differences (p < 0.05) between the constant velocity phases found by each method: the largest segment was obtained with the windowing method; the second one, with the algorithm; and the smallest, with data reduction technique. The point of peak torque was not affected by none of the techniques, but significant differences (p < 0.05) were found between the data including and not including the VO phase, concerning total work, time interval, and average length of load range: VO represents more than 10% of the amount calculated in constant velocity phase

  18. The Effects of Kinetic Energy on Concentric and Eccentric Isokinetic Work

    PubMed Central

    Boggess, Brian; Moffit, Jeff; Morales, Jacobo; Anderson, Tim

    2008-01-01

    This investigation examined inertial effects on work output during isokinetic concentric knee extension and eccentric knee flexion. Total work (Wtotal) included work due to kinetic energy (Wkin), with respect to gravity (Wgrav), and against the dynamometer (Wdyn). Eighteen resistance-trained participants (9 males, 9 females) performed maximal voluntary concentric (90, 150, 210, 270 deg/s) and eccentric (-150, -90, -30 deg/s) actions with the dominant leg. Differences between work measurement type (WMT), i.e., gravity-corrected work and Wtotal, were assessed. ANOVA (2 WMT x 2 mode x 2 gender x 4 speed) revealed significant main effects (p < 0. 05) for both factors concentrically but only for WMT eccentrically. It was concluded that the effect of kinetic energy during isokinetic leg extension may elicit differences in measurement where the associated error (Kerr) significantly increases with increasing velocity concentrically and decreases eccentrically. Key pointsTotal isokinetic work is underestimated by standard gravity corrected techniques.Standard gravity corrected work measurements overestimate isometric eccentric total work.The overestimation of isometric eccentric total work increases with greater angular velocity. PMID:24150138

  19. Neuromuscular adaptations to 8-week strength training: isotonic versus isokinetic mode.

    PubMed

    Remaud, Anthony; Cornu, Christophe; Guével, Arnaud

    2010-01-01

    Previous studies attempted to compare the effectiveness of isokinetic and isotonic training. However, they have provided conflicting results. The purpose of this study was to compare the effects of isotonic versus isokinetic standardized concentric strength training programs of the knee extensors on the neuromuscular system. The standardization of these two training programs was ensured by the equalization of the total external amount of work performed and the mean angular movement velocity. Thirty healthy male students were randomly assigned to the isotonic (IT; n = 11), the isokinetic (IK; n = 11) or the control (C; n = 8) group. Both IT and IK groups trained their dominant lower leg 3 sessions/week for 8 weeks on a dynamometer. The IT group exercised using a preset torque of 40% of the maximal voluntary isometric torque at 70 degrees (0 degrees = leg in horizontal position). The IK group exercised at a velocity ranging between 150 degrees and 180 degrees s(-1). Isotonic, isokinetic and isometric tests were performed on a dynamometer before and after strength training. Surface electromyographic activity of vastus lateralis, vastus medialis, rectus femoris, semitendinosus and biceps femoris muscles was recorded during the tests. Significant strength increases in both dynamic and static conditions were noticed for IT and IK groups without any significant difference between the two trained groups. Agonist muscle activity also increased with training but no change in antagonist muscle co-activity was observed. The two training methods could be proposed by clinicians and athletic coaches to improve concentric muscle strength in dynamic and static conditions.

  20. Reliability of an isokinetic dorsiflexion and plantar flexion apparatus.

    PubMed

    Wennerberg, D

    1991-01-01

    The insufficient amount of research to support high reliability of isokinetic ankle joint adaptations indicates a need for study in this area. Certain brands of isokinetic machinery and specific joint apparatuses have been studied for consistency in adequate numbers of investigations, while there has been little research done on other brands and all other joint adaptations besides the knee. We studied the Biodex B-2000 dorsiflexion and plantar flexion adaptation for reliability between two trials of contractions measuring peak torque. Our results showed generally low reliability coefficients between trials in every condition tested with respect to each ankle motion and two different isokinetic speeds. No connection was seen between ankle motion and isokinetic speed with respect to reliability. Attempts to pinpoint reasons behind inconsistencies concentrate upon such areas as the subject testing position, time between trials, and machine structure. Areas of further study might deal with different brands of isokinetic devices and also the different joint adaptations.

  1. The effect of velocity and gender on load range during knee extension and flexion exercise on an isokinetic device.

    PubMed

    Brown, L E; Whitehurst, M; Gilbert, R; Buchalter, D N

    1995-02-01

    Limb acceleration and deceleration during exercise on an isokinetic device encounter no machine-offered resistance. The purpose of this study was to quantify the relationship between velocity and range of motion that is sustained at a predetermined isokinetic velocity, termed load range, during concentric knee extension and flexion exercise. Nine male and nine female subjects performed three maximal concentric reciprocal knee extension and flexion repetitions at 60, 120, 180, 240, 360, and 450 degrees/sec. Extension and flexion results revealed a significant (p < 0.05) increase in acceleration and deceleration range of motion while load range significantly decreased with increasing velocity. Males exhibited greater load range and less acceleration range of motion than females at 240, 360, and 450 degrees/sec, while deceleration range of motion was not different between genders at any speed. These results demonstrate an inverse relationship between isokinetic velocity and load range and suggest a need to carefully consider velocity selection when performing exercise on an isokinetic device.

  2. Resistance training improves isokinetic strength and metabolic syndrome-related phenotypes in postmenopausal women.

    PubMed

    Oliveira, Pedro Ferreira Alves; Gadelha, André Bonadias; Gauche, Rafael; Paiva, Flávio Macedo Lahud; Bottaro, Martim; Vianna, Lauro C; Lima, Ricardo Moreno

    2015-01-01

    To examine the effects of resistance training (RT) on metabolic syndrome-related phenotypes in postmenopausal women. Twenty-two postmenopausal women (65.0±4.2 years) underwent 12 weeks of whole body progressive training with intensity prescribed based on rating of perceived exertion. Dominant knee extension strength was assessed using an isokinetic dynamometer before and after the intervention. Moreover, all volunteers had blood samples collected for lipid profile, glycemic control, and C-reactive protein analyses. Waist circumference and arterial blood pressure were also measured at baseline and after the training period. Student's t-tests for paired samples and repeated measures ANOVA were used to compare dependent variables, and statistical significance was set at P<0.05. Isokinetic muscle strength significantly increased (P<0.01) with training. It was observed that waist circumference as well as total and low-density lipoprotein cholesterol levels significantly decreased with training (P<0.01). Total cholesterol/high-density lipoprotein cholesterol ratio, an important marker of cardiovascular disease incidence, was also significantly reduced (from 3.91±0.91 to 3.60±0.74; P<0.01) after the program. Blood glucose, basal insulin, and homeostatic model assessment of insulin resistance were also significantly reduced (P<0.01). No significant alterations were observed for resting blood pressure, triglycerides, or C-reactive protein. Based on the observed results, it can be concluded that a 12-week progressive RT program, besides increasing isokinetic muscle strength, induces beneficial alterations on metabolic syndrome-related phenotypes in postmenopausal women. These findings highlight this mode of exercise as an important component of public health promotion programs for aged women. RT improves isokinetic strength and metabolic syndrome-related phenotypes in postmenopausal women.

  3. Isokinetic testing in patients with neuromuscular diseases: a focused review.

    PubMed

    El Mhandi, Lhassan; Bethoux, François

    2013-02-01

    This literature review aimed to study the use of isokinetic testing in patients with neuromuscular diseases (NMDs) and to identify directions for future research of isokinetic testing. The MEDLINE (January 1, 1965, to July 1, 2010), Cumulative Index to Nursing and Allied Health (1980 to May 2010), and Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2009) electronic databases were searched. The literature search was conducted using the keywords muscle assessment, muscle strength, evaluation, isokinetic, neuromuscular diseases, muscle fatigue, functional test, rehabilitation, and literature search. Relevant references cited in the selected articles were also considered, regardless of the year of publication. The search strategy yielded 13 articles involving a variety of patients with known NMDs. All studies demonstrated that isokinetic dynamometry is appropriate and safe for ambulatory patients with NMDs. Isokinetic testing has proven to be reliable (intratest/intertest correlation coefficient ranged from 0.65 to 0.98), with the proximal muscles having the highest reliability, and sensitive to disease progression and to the effects of various therapeutic interventions. However, isokinetic testing has never gained wide acceptance, partly because of concerns about stabilizing the dynamometer and the subject during the test and of the lack of standardized protocols for isokinetic strength measurement. Isokinetic testing is an important part of the comprehensive evaluation and rehabilitation of patients with NMD. Research has demonstrated its efficacy in providing clinically relevant information. When integrated with a complete history, physical examination, and functional evaluation, isokinetic testing and exercise can be a valuable tool for the clinician in the assessment, rehabilitation, and performance enhancement of patients with NMD. Such equipment, however, has several disadvantages, rendering it usually impractical in the clinical

  4. Comparison of blood pressure response to isokinetic and weight-lifting exercise.

    PubMed

    Sale, D G; Moroz, D E; McKelvie, R S; MacDougall, J D; McCartney, N

    1993-01-01

    Brachial arterial pressure, oesophageal pressure, and knee joint angle were monitored in eight untrained young men as they performed bilateral leg-press actions (simultaneous hip and knee extension and ankle plantarflexion) against resistance. Single maximal leg-press actions on an isokinetic device evoked mean peak arterial (systolic/diastolic) pressures of 35.4/26.2 and 34.0/23.4 kPa at lever arm velocities of 0.262 and 1.31 rad.s-1, respectively. The corresponding oesophageal pressures were 13.2 and 10.4 kPa, respectively. Although the peak force was 30% greater, and duration of the action 3-4 times longer at 0.262 than 1.31 rad.s-1, the arterial and oesophageal pressure responses did not differ. On a weight-lifting machine, a set of repetitions [mean (SEM): 11 (3)] to failure at 80-90% one repetition maximum evoked peak arterial pressures of 45.5/32.8 kPa; the corresponding oesophageal pressure was 15.7 kPa. The peak systolic and diastolic pressures observed during weight-lifting were significantly (P < 0.05) higher than during isokinetic actions at both velocities, whereas oesophageal pressure was more elevated only in relation to isokinetic actions at the higher velocity. These data indicate that resisted leg-press actions cause extreme elevations in arterial blood pressure. The degree of voluntary effort is the major determinant of the blood pressure response, rather than the resistance mode or the type (concentric, eccentric, isometric) of muscle action. Repetitive resistance exercise (e.g. a set of repetitions to failure in weight-lifting) tends to produce greater pressure elevations than isolated, single maximal effort actions.

  5. Evaluation of Elbow Stretch Reflex Using a Portable Hand-driven Isokinetic System in Normal Adults

    PubMed Central

    Seo, Jeong-Hwan; Song, Chul-Gyu; Ko, Myoung-Hwan; Park, Sung-Hee

    2011-01-01

    Objective To evaluate normal healthy persons without spasticity to observe normal findings of the elbow stretch reflex using a newly developed, portable, hand-driven spasticity-measuring system. Method Thirty normal persons without any disease involving the central or peripheral nervous system were enrolled in this study. The portable hand-driven isokinetic system is able to measure the joint angle, angular velocity, electromyographic (EMG) signals, and torque during elbow passive extension-flexion. One set of 10 passive elbow extension and flexion movements was performed for data acquisition at each angular velocity, including 60, 90, 120, 150 and 180 degrees per second (°/sec). Electromyographic data were collected from the biceps brachii and the triceps brachii. Torque data were collected from sensors around the wrist. Results We were able to detect EMG activity and torque in all subjects by using the new portable hand-driven isokinetic system. EMG activity and torque increased with incremental increase of angular velocities. The joint angle of maximal EMG activity according to different angular velocities did not show any significant difference (116°-127° in elbow extension and 37°-66° in elbow flexion). The joint angles of maximal torque according to different angular velocities were not significantly different either. Conclusion Using the portable hand-driven isokinetic system on the elbows of normal subjects, we were able to obtain expected results. By considering our normal findings of the elbow stretch reflex using this system, we propose that the various aspects of spasticity-related data can be measured successfully. PMID:22506169

  6. Isokinetic shoulder rotator muscles in wheelchair athletes.

    PubMed

    Bernard, P L; Codine, P; Minier, J

    2004-04-01

    To assess the influence of wheelchair propulsion and neurological level on isokinetic shoulder rotational strength. University of Montpellier, France Data were evaluated in three groups of subjects as follows: 12 nonathletes, 15 tennis players and 21 wheelchair athletes. We then compared 12 high paraplegic athletes (HPA) and nine low paraplegic athletes (LPA) within the group of 21 wheelchair athletes: The isokinetic tests were performed in the seated 45 degrees abducted test position in the scapular plane at 60, 180 and 300 degrees s(-1) for both shoulders. Peak torque and mean power values were gathered and, from these values, the internal/external rotation ratios were calculated. Intergroup comparison showed an influence of lesion and sport on peak torque at 180 and 300 degrees s(-1) for the internal rotators and significantly higher values of the internal/external ratios in the wheelchair athlete group. For mean power, we observed significant differences under all test conditions and significant differences for ratio only on the dominant side at 180 degrees s(-1) and on the dominant side at 300 degrees s(-1). Comparison of the two groups of paraplegic athletes showed significantly higher values of peak torque and mean power of the external rotators in the LPA for all test conditions. Neurological level of lesion does not systematically influence the development of internal rotator muscles; in contrast, the participation of the external rotators appears strongly correlated to neurological level. The comparison of the two sides in the two paraplegic groups showed that in two-thirds of the cases the values of the external rotators were significantly higher than those of the internal rotators on the nondominant side for peak torque and mean power. Ratios on the dominant side were systematically higher than on the nondominant side, with significant differences also noted in two-thirds of the cases. These results raise questions about the influence of neurological

  7. Importance of muscle phosphocreatine during intermittent maximal cycling.

    PubMed

    Trump, M E; Heigenhauser, G J; Putman, C T; Spriet, L L

    1996-05-01

    To examine the importance of phosphocreatine (PCr) degradation in maintaining power output during maximal intermittent cycling, seven healthy men completed three bouts of isokinetic cycling (30 s, 100 revolutions/min) with 4 min of rest between bouts. After bout 2, blood flow to one leg was occluded by cuffing the thigh (Cuff) during the rest period to prevent PCr resynthesis while the circulation to the other leg was intact (Cont). The cuff was then removed and bout 3 completed. Muscle biopsies were sampled from the vastus lateralis of both legs just before and immediately after bout 3. Total work produced by the Cuff and Cont legs was similar during bouts 1 (9.3 +/- 0.5 and 9.6 +/- 0.5 kJ, respectively) and 2 (8.1 +/- 0.4 and 8.3 +/- kJ, respectively). Cuffing prevented the resynthesis of PCr because pre-bout 3 contents were 20.7 +/- 8.4 and 63.0 +/- 3.3 mmol/kg dry muscle in the Cuff and Cont legs, respectively. Cuffing also resulted in significantly higher muscle levels of lactate, H+ concentration (287 +/- 26 vs. 217 +/- 15 nM), ADP, AMP, and acetyl-CoA before bout 3 but had no effect on other glycolytic intermediates, ATP, or acetylcarnitine. Total work in bout 3 was significantly reduced by 15% in the Cuff leg (5.8 +/- 0.4 vs. 6.8 +/- 0.6 kJ). PCr degradation during bout 3 was 3.1 and 47.5 mmol/kg dry muscle in the Cuff and Cont legs, respectively, and lactate accumulation was minimal in both legs. Changes in all other metabolites during bout 3 were not different between legs. The results suggest that PCr contributed approximately 15% of the total ATP provision during the third 30-s bout of maximal isokinetic cycling and that most of the ATP was provided during the initial 15 s. Muscle glycogenolysis contributed minimally to ATP provision (approximately 10-15%) during the third 30-s bout, suggesting that aerobic metabolism becomes the dominant source of ATP during this model of repeated sprinting.

  8. Isokinetic Dynamometry in Healthy Versus Sarcopenic and Malnourished Elderly: Beyond Simple Measurements of Muscle Strength.

    PubMed

    Cramer, Joel T; Jenkins, Nathaniel D M; Mustad, Vikkie A; Weir, Joseph P

    2015-05-05

    This study quantified systematic and intraindividual variability among three repetitions of concentric isokinetic knee extension and flexion tests to determine velocity-related differences in peak torque (PT) and mean power (MP) in healthy elderly (HE) versus sarcopenic and malnourished elderly (SME). In total, 107 HE (n = 54 men, n = 53 women) and 261 SME (n = 101 men, n = 160 women) performed three maximal concentric isokinetic knee extension and flexion repetitions at 60°·s(-1) and 180°·s(-1). PT for Repetition 3 was lower than Repetitions 1 and 2, while MP for Repetition 1 was lower than Repetitions 2 and 3 in SME. Intraindividual variability among repetitions was correlated with strength, but not age, and was greater in SME, during knee flexion, and at 180°·s(-1). Velocity-related decreases in PT from 60°·s(-1) to 180°·s(-1) were more pronounced in SME. In summary, (a) the repetition with the highest PT value may be the best indicator of maximal strength, while the average may indicate strength maintenance in SME; (b) intraindividual variability among repetitions reflects functional decrements from HE to SME; and (c) decreases in PT from 60°·s(-1) to 180°·s(-1) may reflect greater losses of fast-twitch (type II) fiber function.

  9. Symptomatic and Functional Responses to Concentric-Eccentric Isokinetic Versus Eccentric-Only Isotonic Exercise

    PubMed Central

    Parr, Jeffrey J.; Yarrow, Joshua F.; Garbo, Carolyn M.; Borsa, Paul A.

    2009-01-01

    Abstract Context: Rehabilitation protocols involving eccentric resistance exercise performed with loading more than 100% concentric 1-repetition maximum are effective in increasing muscle function in both healthy and injured populations. The mode of eccentric exercise (isokinetic versus isotonic) may be an important factor in limiting symptoms of delayed-onset muscle soreness and in improving muscle function after training. Objective: To compare functional and symptomatic responses after an eccentric-only (ECC) isotonic exercise protocol and after a combined concentric-eccentric (CON-ECC) isokinetic exercise protocol matched for total exercise volume. Design: Observational study. Setting: Controlled research laboratory. Patients or Other Participants: Twenty-four healthy, untrained, college-aged men (n  =  12) and women (n  =  12). Intervention(s): Participants were randomly assigned to the ECC isotonic or CON-ECC isokinetic exercise group and performed a single bout of resistance exercise involving the elbow flexors. Main Outcome Measure(s): Measurements of elbow flexion and extension, isometric strength, and muscle point tenderness were obtained before exercise (baseline) and during follow-up sessions (days 2, 4, 7, and 14). Separate 1-way analyses of variance and repeated-measures analyses of variance were used to determine outcome differences. Tukey post hoc testing was performed when indicated. Results: At baseline, no differences were present between groups for any measure. The ECC isotonic exercise protocol resulted in a 30% to 36% deficit in muscle strength, a 5% to 7% reduction in elbow flexion, and a 6% to 8% reduction in elbow extension at follow-up days 2 and 4 (P < .01). The CON-ECC isokinetic exercise protocol did not alter muscle strength or range of motion at any time when compared with baseline. Muscle point tenderness increased from baseline on days 2 and 4 in both groups (P < .05) but was not different between groups throughout the

  10. Isometric and isokinetic torque curves at the knee joint.

    PubMed

    Yoon, T S; Park, D S; Kang, S W; Chun, S I; Shin, J S

    1991-03-01

    Isometric and isokinetic torques of bilateral quadriceps and hamstrings were measured with Isokinetic Rehabilitation and Testing System (Model No. Cybex 340) on 40 normal untrained subjects, 20 males and 20 females, ranging between the ages of 23 and 35 years. The mean peak isometric and isokinetic torque values of both muscle groups showed no significant differences between dominant (right) and nondominant (left) limbs in both sexes; however there were significant differences between the male and the female. As the angular velocity increased, the peak torque significantly decreased, and the point of peak torque output occurred significantly later in the range of motion for quadriceps and hamstrings (p less than 0.01). There were no significant changes in the hamstrings to quadriceps (H/Q) ratios as the angular velocity increased. However, there were significant differences of mean H/Q ratio between male and female (p less than 0.01). Height had significant positive correlation with peak isometric and isokinetic torques for both quadriceps and hamstrings (p less than 0.01). Weight was found to correlate significantly with peak isometric and isokinetic torques (p less than 0.01). The mean isometric torques were significantly higher than the mean isokinetic torques for any joint angles in both sexes (p less than .01).

  11. Isokinetic Testing in Evaluation Rehabilitation Outcome After ACL Reconstruction

    PubMed Central

    Cvjetkovic, Dragana Dragicevic; Bijeljac, Sinisa; Palija, Stanislav; Talic, Goran; Radulovic, Tatjana Nozica; Kosanovic, Milkica Glogovac; Manojlovic, Slavko

    2015-01-01

    Introduction: Numerous rehab protocols have been used in rehabilitation after ACL reconstruction. Isokinetic testing is an objective way to evaluate dynamic stability of the knee joint that estimates the quality of rehabilitation outcome after ACL reconstruction. Our investigation goal was to show importance of isokinetic testing in evaluation thigh muscle strength in patients which underwent ACL reconstruction and rehabilitation protocol. Subjects and methods: In prospective study, we evaluated 40 subjects which were divided into two groups. Experimental group consisted of 20 recreational males which underwent ACL reconstruction with hamstring tendon and rehabilitation protocol 6 months before isokinetic testing. Control group (20 subjects) consisted of healthy recreational males. In all subjects knee muscle testing was performed on a Biodex System 4 Pro isokinetic dynamo-meter et velocities of 60°/s and 180°/s. We followed average peak torque to body weight (PT/BW) and classic H/Q ratio. In statistical analysis Student’s T test was used. Results: There were statistically significant differences between groups in all evaluated parameters except of the mean value of PT/BW of the quadriceps et velocity of 60°/s (p>0.05). Conclusion: Isokinetic testing of dynamic stabilizers of the knee is need in diagnostic and treatment thigh muscle imbalance. We believe that isokinetic testing is an objective parameter for return to sport activities after ACL reconstruction. PMID:25870471

  12. Isokinetic Testing in Evaluation Rehabilitation Outcome After ACL Reconstruction.

    PubMed

    Cvjetkovic, Dragana Dragicevic; Bijeljac, Sinisa; Palija, Stanislav; Talic, Goran; Radulovic, Tatjana Nozica; Kosanovic, Milkica Glogovac; Manojlovic, Slavko

    2015-02-01

    Numerous rehab protocols have been used in rehabilitation after ACL reconstruction. Isokinetic testing is an objective way to evaluate dynamic stability of the knee joint that estimates the quality of rehabilitation outcome after ACL reconstruction. Our investigation goal was to show importance of isokinetic testing in evaluation thigh muscle strength in patients which underwent ACL reconstruction and rehabilitation protocol. In prospective study, we evaluated 40 subjects which were divided into two groups. Experimental group consisted of 20 recreational males which underwent ACL reconstruction with hamstring tendon and rehabilitation protocol 6 months before isokinetic testing. Control group (20 subjects) consisted of healthy recreational males. In all subjects knee muscle testing was performed on a Biodex System 4 Pro isokinetic dynamo-meter et velocities of 60°/s and 180°/s. We followed average peak torque to body weight (PT/BW) and classic H/Q ratio. In statistical analysis Student's T test was used. There were statistically significant differences between groups in all evaluated parameters except of the mean value of PT/BW of the quadriceps et velocity of 60°/s (p>0.05). Isokinetic testing of dynamic stabilizers of the knee is need in diagnostic and treatment thigh muscle imbalance. We believe that isokinetic testing is an objective parameter for return to sport activities after ACL reconstruction.

  13. [Isokinetic assessment of ankles in patients with rheumatoid arthritis].

    PubMed

    Oliveira, Silvia Cristina Gutierrez; Oliveira, Leda Magalhaes; Jones, Anamaria; Natour, Jamil

    2015-01-01

    The foot and ankle in rheumatoid arthritis undergo highly destructive synovitis with loss of muscle strength. To evaluate the muscle strength of ankles in patients with rheumatoid arthritis based on isokinetic dynamometry parameters. Thirty patients with a diagnosis of rheumatoid arthritis involving the ankle(s) and 30 healthy subjects (control group) matched for age, gender, race, body mass index and lower limb dominance were studied. Dorsiflexion, plantarflexion, inversion and eversion were evaluated in all subjects on an isokinetic Cybex Norm dynamometer. The variables were compared between the rheumatoid arthritis and control groups and between the right and left ankles, and the dorsiflexor/plantar flexor and invertor/evertor muscle strength ratio was determined. Patients with rheumatoid arthritis performed statistically worse in the isokinetic dynamometry test for all ankle movements. The muscle strength ratio between dorsiflexors and plantar flexors was different in the two groups. No significant differences were observed in the invertor and evertor ratios. In the two groups the plantar flexor musculature was statistically stronger than dorsiflexors. We conclude that patients with rheumatoid arthritis perform worse in isokinetic dynamometry regarding all ankle movements than control subjects, with similar isokinetic test results being observed for the right and left side in both groups, with few exceptions. Isokinetic evaluation posed no additional risk such as important pain or inflammatory activity to patients with rheumatoid arthritis. Copyright © 2014 Elsevier Editora Ltda. All rights reserved.

  14. Neuromuscular Changes and Damage after Isoload versus Isokinetic Eccentric Exercise.

    PubMed

    Doguet, Valentin; Nosaka, Kazunori; Plautard, Mathieu; Gross, Raphaël; Guilhem, GaËL; Guével, Arnaud; Jubeau, Marc

    2016-12-01

    This study compared the effects of isoload (IL) and isokinetic (IK) knee extensor eccentric exercises on changes in muscle damage and neuromuscular parameters to test the hypothesis that the changes would be different after IL and IK exercises. Twenty-two young men were paired based on their strength and placed in the IL (N = 11) or the IK (N = 11) group. The IL group performed 15 sets of 10 eccentric contractions with a 150% of predetermined one-repetition maximum load. The IK group performed 15 sets of several maximal eccentric contractions matched set by set for the total amount of work and mean angular velocity with the IL group. Muscle damage markers (voluntary isometric peak torque, muscle soreness, and creatine kinase activity) and neuromuscular variables (e.g., voluntary activation, H-reflex, M-wave, and evoked torque) were measured before, immediately after, and 24, 48, 72, and 96 h postexercise. Voluntary isometric peak torque decreased to the same extent (P = 0.94) in both groups immediately after (IL = -40.6% ± 13.8% vs IK = -42.4% ± 10.2%) to 96 h after the exercise (IL = -21.8% ± 28.5% vs IK = -26.7% ± 23.5%). Neither peak muscle soreness (IL = 48.1 ± 28.2 mm vs IK = 54.7 ± 28.9 mm, P = 0.57) nor creatine kinase activity (IL = 12,811 ± 22,654 U·L vs IK = 15,304 ± 24,739 U·L, P = 0.59) significantly differed between groups. H-reflex (IL = -23% vs IK = -35%) and M-wave (IL = -10% vs IK = -17%) significantly decreased immediately postexercise similarly between groups. The changes in muscle damage and neuromuscular function after the exercise are similar between IL and IK, suggesting that resistance modality has little effects on acute muscle responses.

  15. Reliability of Isometric and Eccentric Isokinetic Shoulder External Rotation.

    PubMed

    Papotto, Brianna M; Rice, Thomas; Malone, Terry; Butterfield, Timothy; Uhl, Tim L

    2016-06-06

    Shoulder external rotators are challenged eccentrically throughout the deceleration phase of throwing, which is thought to contribute to overuse injuries. To evaluate the effectiveness of intervention programs, as well as identifying deficits, reliable and responsive measures of isometric and eccentric shoulder external rotation are necessary. Previously, isometric measures have primarily tested a single position, and eccentric measures have not been found to have high reliability. To examine the between-days reliability of multiple-angle isometric and dynamic eccentric isokinetic testing of shoulder external rotation. Repeated measures. 10 healthy subjects (age 30 ± 12 y, height 166 ± 13 cm, mass 72 ± 10 kg). Average isometric peak torque of shoulder external rotation at 7 angles was measured. From these values, the angle of isometric peak torque was calculated. Dynamic eccentric average peak torque, average total work, and average angle of peak torque were measured. Between-days reliability was high for average peak torque during isometric contractions at all angles (ICC ≥ .85), as it was for dynamic eccentric average peak torque (ICC ≥ .97). The estimated angle of isometric peak torque (ICC ≤ .65) was not highly reliable between days. The average angle of peak torque from the eccentric testing produced inconsistent results. Average total work of dynamic eccentric shoulder external rotation was found to be highly reliable between days (ICC ≥ .97). Aspects of force such as peak torque and total work in isometric and eccentric testing of the shoulder external-rotator muscles can be measured reliably between days and used to objectively evaluate shoulder strength and identify changes when they occur. Angle measurements of peak torque could provide insight into the mechanical properties of the posterior shoulder muscles but were found to be inconsistent between days.

  16. No reserve in isokinetic cycling power at intolerance during ramp incremental exercise in endurance-trained men.

    PubMed

    Ferguson, Carrie; Wylde, Lindsey A; Benson, Alan P; Cannon, Daniel T; Rossiter, Harry B

    2016-01-01

    During whole body exercise in health, maximal oxygen uptake (V̇o2max) is typically attained at or immediately before the limit of tolerance (LoT). At the V̇o2max and LoT of incremental exercise, a fundamental, but unresolved, question is whether maximal evocable power can be increased above the task requirement, i.e., whether there is a "power reserve" at the LoT. Using an instantaneous switch from cadence-independent (hyperbolic) to isokinetic cycle ergometry, we determined maximal evocable power at the limit of ramp-incremental exercise. We hypothesized that in endurance-trained men at LoT, maximal (4 s) isokinetic power would not differ from the power required by the task. Baseline isokinetic power at 80 rpm (Piso; measured at the pedals) and summed integrated EMG from five leg muscles (ΣiEMG) were measured in 12 endurance-trained men (V̇o2max = 4.2 ± 1.0 l/min). Participants then completed a ramp incremental exercise test (20-25 W/min), with instantaneous measurement of Piso and ΣiEMG at the LoT. Piso decreased from 788 ± 103 W at baseline to 391 ± 72 W at LoT, which was not different from the required ramp-incremental flywheel power (352 ± 58 W; P > 0.05). At LoT, the relative reduction in Piso was greater than the relative reduction in the isokinetic ΣiEMG (50 ± 9 vs. 63 ± 10% of baseline; P < 0.05). During maximal ramp incremental exercise in endurance-trained men, maximum voluntary power is not different from the power required by the task and is consequent to both central and peripheral limitations in evocable power. The absence of a power reserve suggests both the perceptual and physiological limits of maximum voluntary power production are not widely dissociated at LoT in this population.

  17. Isokinetic eccentric exercise of quadriceps femoris does not affect running economy.

    PubMed

    Vassilis, Paschalis; Vassilios, Baltzopoulos; Vassilis, Mougios; Athanasios, Jamurtas Z; Vassilis, Theoharis; Christina, Karatzaferi; Yiannis, Koutedakis

    2008-07-01

    The purpose of this study was to investigate whether running economy is affected by isokinetic eccentric exercise designed to cause muscle damage. Twenty-four young healthy men performed 120 maximal voluntary eccentric actions at each thigh's quadriceps muscle at an angular velocity of 60 degrees .s. The participants were then randomly divided into 2 equal groups, 1 of which exercised 24 hours later, while the other group rested. Muscle damage indicators (i.e., serum creatine kinase, delayed onset muscle soreness, and eccentric, concentric, and isometric peak torque) and running economy indicators (i.e., oxygen consumption, pulmonary ventilation, respiratory exchange ratio, respiratory rate, and heart rate during treadmill running at 2.2 and 3.3 m.s) were assessed prior to and 48 hours following the eccentric exercise. All muscle damage indicators changed significantly in both groups (p < 0.05) in a way suggestive of considerable muscle damage. Running economy indicators of the exercise group demonstrated only an elevation of respiratory rate at 48 hours (p < 0.05) and a tendency to lower economy compared to the resting group. It can be concluded that isokinetic eccentric exercise applied to the quadriceps femoris muscles did not affect running economy 48 hours later and that resting during this period tended to result in more economical running compared to exercising at 24 hours.

  18. Dynamic joint and muscle forces during knee isokinetic exercise.

    PubMed

    Wei, S H

    2000-10-01

    Isokinetic exercise has been commonly used in knee rehabilitation, conditioning and research in the past two decades. Although many investigators have used various experimental and theoretical approaches to study the muscle and joint force involved in isokinetic knee extension and flexion exercises, only a few of these studies have actually distinguished between the tibiofemoral joint forces and muscle forces. Therefore, the objective of this study was to specify, via an eletromyography(EMG)-driven muscle force model of the knee, the magnitude of the tibiofemoral joint and muscle forces acting during isokinetic knee extension and flexion exercises. Fifteen subjects ranging from 21 to 36 years of age volunteered to participate in this study. A Kin Com exercise machine (Chattecx Corporation, Chattanooga, TN, U.S.A.) was used as the loading device. An EMG-driven muscle force model was used to predict muscle forces, and a biomechanical model was used to analyze two knee joint constraint forces; compression and shear force. The methods used in this study were shown to be valid and reliable (r > 0.84 andp < 0.05). The effects on the tibiofemoral joint force during knee isokinetic exercises were compared with several functional activities that were investigated by earlier researchers. The muscle forces generated during knee isokinetic exercise were also obtained. Based on the findings obtained in this study, several therapeutic justifications for knee rehabilitation are proposed.

  19. Longitudinal changes in isokinetic leg strength in 10-14-year-olds.

    PubMed

    De Ste Croix, M B A; Armstrong, N; Welsman, J R; Sharpe, P

    2002-01-01

    This study used multilevel regression modelling to longitudinally investigate the influences of age, sex, body size, skinfold thicknesses and maturity on the development of isokinetic knee extension and flexion on eight occasions over a 4-year period. Forty-one subjects (20 boys and 21 girls) were measured and 295 isokinetic leg strength tests and associated measures were successfully completed. Subjects were aged 10.0 +/- 0.3 years at the onset of the study. Stature, body mass, triceps and subscapular skinfold thicknesses, and sexual maturation (according to pubic hair development) were assessed at each test occasion. Isokinetic concentric knee extension and flexion of the dominant leg were determined to elicit maximal peak extension (PET) and flexion torque (PFT). Statistical significance was accepted at p < 0.05. Multilevel regression modelling indicated that stature and mass were significant predictors of both PET and PFT. Age and maturity were non-significant explanatory variables once stature and mass had been accounted for. Skinfold thickness exerted a significant negative effect independent of mass and stature on PFT but not PET. At test occasion 8, cross-sectional areas (CSAs) of the knee extensors (ExCSA) and flexors (FlexCSA) were determined using magnetic resonance imaging on 23 boys and 14 girls and examined as predictors of isokinetic leg strength. There were no significant sex-related differences in PET or PFT. Pearson product moment correlation coefficients indicated a significant relationship between ExCSA and PET and FlexCSA and PFT for both boys and girls. Analysis of covariance (ANCOVA) demonstrated that ExCSA and FlexCSA were significant explanatory variables for PET and PFT, respectively, but became non-significant once stature and mass had been introduced into the analysis. To conclude, there were no significant sex differences in PET or PFT between the ages of 10 and 14 years and the development of PET and PFT could be accounted for by the

  20. Comparison of two methodological approaches for the mechanical analysis of single-joint isoinertial movement using a customised isokinetic dynamometer().

    PubMed

    Plautard, Mathieu; Guilhem, Gaël; Fohanno, Vincent; Nordez, Antoine; Cornu, Christophe; Guével, Arnaud

    2017-03-16

    Compared to isokinetic and isometric tests, isoinertial movements have been poorly used to assess single-joint performance. Two calculation procedures were developed to estimate mechanical performance during single-joint isoinertial movements performed on a customised isokinetic dynamometer. The results were also compared to appreciate the effects of measurement systems and calculation procedures. Five participants performed maximal knee extensions at four levels of resistance (30, 50, 70 and 90% of the one-repetition maximum, 1-RM). Joint angular velocity and torque were assessed from customised isokinetic dynamometer measures (method A) and from weight stack kinematic (method B). Bland-Altman plots and mean percent differences (Mdiff) were used to assess the level of agreement for mean and peak angular velocity and torque. A Passing-Bablok regression was performed to compare the angular velocity-angle and torque-angle relationships computed from the two analysis methods. The results showed a high level of agreement for all mechanical parameters (Mdiff < 6% for all parameters). No statistically significant differences were observed between methods A and B in terms of angular velocity-angle and torque-angle relationships except at 30% of 1-RM for the torque-angle relationship. Both methodologies provide comparable values of angular velocity and torque, offering alternative approaches to assess neuromuscular function from single-joint isoinertial movements.

  1. Acute effects of static and dynamic stretching on hamstring eccentric isokinetic strength and unilateral hamstring to quadriceps strength ratios.

    PubMed

    Ayala, Francisco; De Ste Croix, Mark; Sainz De Baranda, Pilar; Santonja, Fernando

    2013-01-01

    The main purposes of this study were to investigate the acute effects of static and dynamic lower limb stretching routines: (a) on peak torque, total external work and joint angle at peak torque of the hamstrings during maximal eccentric isokinetic leg flexion; (b) on unilateral hamstring to quadriceps (H/Q) strength ratios; as well as (c) to determine whether static and dynamic routines elicit similar responses. A total of 49 active adults completed the following intervention protocols in a randomised order on separate days: (a) non-stretching (control condition), (b) static stretching, and (c) dynamic stretching. After the stretching or control intervention, eccentric isokinetic peak torque, the angle of peak torque and total external work were assessed with participants prone at 1.04 and 3.14 rad · s(-1). Unilateral strength ratios of the knee were also recorded. Measures were compared via a fully-within-groups factorial analysis of variance (ANOVA). There were no main effects for eccentric isokinetic peak torque, angle of peak torque, total external work and unilateral H/Q strength ratios. The results suggest that dynamic and static stretching has no influence on eccentric strength profile and unilateral H/Q strength ratios and hence both forms of stretching do not reduce these two primary risk factors for muscle injury.

  2. Effects of Short-Term Isokinetic Training on Standing Long-Jump Performance in Untrained Men.

    ERIC Educational Resources Information Center

    Morriss, Calvin J.; Tolfrey, Keith; Coppack, Russell J.

    2001-01-01

    Evaluated the effects of a brief isokinetic training program on quadriceps and hamstring peak torque (PT) and standing long-jump performance. Tests on 12 untrained men indicated that the brief training program was at least as effective in improving quadriceps isokinetic (but not hamstring) PT. PT gains subsequent to isokinetic resistance training…

  3. Effects of Short-Term Isokinetic Training on Standing Long-Jump Performance in Untrained Men.

    ERIC Educational Resources Information Center

    Morriss, Calvin J.; Tolfrey, Keith; Coppack, Russell J.

    2001-01-01

    Evaluated the effects of a brief isokinetic training program on quadriceps and hamstring peak torque (PT) and standing long-jump performance. Tests on 12 untrained men indicated that the brief training program was at least as effective in improving quadriceps isokinetic (but not hamstring) PT. PT gains subsequent to isokinetic resistance training…

  4. The Relationships Among Isokinetic Endurance, Initial Strength Level, and Fiber Type.

    ERIC Educational Resources Information Center

    Clarkson, Priscilla M.; And Others

    1982-01-01

    Knee extension isokinetic peak torque was assessed at four angular velocities, and isokinetic endurance was assessed in eight college age men. Muscle fiber type was determined and related to isokinetic strength and fatigability. Results indicate that factors other than fiber type and initial strength level must influence the rate of isokinetic…

  5. The Relationships Among Isokinetic Endurance, Initial Strength Level, and Fiber Type.

    ERIC Educational Resources Information Center

    Clarkson, Priscilla M.; And Others

    1982-01-01

    Knee extension isokinetic peak torque was assessed at four angular velocities, and isokinetic endurance was assessed in eight college age men. Muscle fiber type was determined and related to isokinetic strength and fatigability. Results indicate that factors other than fiber type and initial strength level must influence the rate of isokinetic…

  6. Relationship between passive properties of the calf muscles and plantarflexion concentric isokinetic torque characteristics.

    PubMed

    Gajdosik, Richard L

    2002-07-01

    The purpose of this study was to use a model of aging to examine the relationships between passive properties of the calf muscles and plantarflexion concentric isokinetic torque characteristics. Eighty-one active women 20-84 years of age were tested using a Kin-Com isokinetic dynamometer interfaced with electromyography (EMG). The passive properties were tested by stretching the muscles from relaxed plantarflexion to a maximal dorsiflexion (DF) angle at a rate of 5 degrees.s(-1) (0.087 rad.s(-1)) with minimal raw EMG activity (<0.05 mV). The maximal concentric torque was tested from maximal passive DF into plantarflexion at four randomly ordered velocities of 30, 60, 120, and 180 degrees.s(-1). Pearson correlation coefficients (Bonferroni adjusted) indicated a hierarchical order of high to moderate positive correlations between four passive properties and the peak and mean concentric torque for all test velocities. Correlation coefficients for the four passive properties ranged from 0.50 to 0.78 ( P<0.001), and the coefficients of determination ( r(2)) from higher to lower were: (1) maximal DF passive resistive torque ( r(2): 0.50-0.62), (2) length extensibility ( r(2): 0.40-0.49), (3) maximal muscle length ( r(2): 0.28-0.41), and (4) passive elastic stiffness in the last half of the full-stretch range of motion ( r(2): 0.25-0.31). The maximal DF passive resistive torque and the length extensibility accounted for 50-62% and 40-49% of the variability in the concentric torque, respectively. The results indicate that the concentrically stronger calf muscles of active women were positively correlated with passively stronger, longer, and stiffer calf muscles, which are characteristics of the calf muscles of younger women. Further studies are needed to examine whether therapeutic interventions, such as stretching and strengthening, can promote adaptations in the calf muscles of older women to attain these more youthful characteristics.

  7. Short-term effects of kinesio tape on joint position sense, isokinetic measurements, and clinical parameters in patellofemoral pain syndrome.

    PubMed

    Kurt, Emine Eda; Büyükturan, Öznur; Erdem, Hatice Rana; Tuncay, Figen; Sezgin, Hicabi

    2016-07-01

    [Purpose] To evaluate the short-term effects of kinesio tape on joint position sense, isokinetic measurements, kinesiophobia, symptoms, and functional limitations in patients with patellofemoral pain syndrome. [Subjects and Methods] A total of 90 patients (112 knees) with patellofemoral pain syndrome were randomized into a kinesio tape group (n=45) or placebo kinesio tape group (n=45). Baseline isokinetic quadriceps muscle tests and measurements of joint position sense were performed in both groups. Pain was measured with a Visual Analog Scale, kinesiophobia with the Tampa kinesiophobia scale, and symptoms and functional limitations with the Kujala pain scale. Measurements were repeated 2 days after kinesio tape application. [Results] No differences were found between baseline isokinetic muscle measurements and those taken 2 days after application. However, significant improvements were observed in the kinesio tape group, with regard to joint position sense, pain, kinesiophobia, symptoms, and functional limitations after treatment. Examination of the differences between pre- and post-treatment values in both groups revealed that the kinesio tape group demonstrated greater improvements compared to the placebo kinesio tape group. [Conclusion] Although short-term kinesio tape application did not increase hamstring muscle strength, it may have improved joint position sense, pain, kinesiophobia, symptoms, and daily limitations.

  8. Short-term effects of kinesio tape on joint position sense, isokinetic measurements, and clinical parameters in patellofemoral pain syndrome

    PubMed Central

    Kurt, Emine Eda; Büyükturan, Öznur; Erdem, Hatice Rana; Tuncay, Figen; Sezgin, Hicabi

    2016-01-01

    [Purpose] To evaluate the short-term effects of kinesio tape on joint position sense, isokinetic measurements, kinesiophobia, symptoms, and functional limitations in patients with patellofemoral pain syndrome. [Subjects and Methods] A total of 90 patients (112 knees) with patellofemoral pain syndrome were randomized into a kinesio tape group (n=45) or placebo kinesio tape group (n=45). Baseline isokinetic quadriceps muscle tests and measurements of joint position sense were performed in both groups. Pain was measured with a Visual Analog Scale, kinesiophobia with the Tampa kinesiophobia scale, and symptoms and functional limitations with the Kujala pain scale. Measurements were repeated 2 days after kinesio tape application. [Results] No differences were found between baseline isokinetic muscle measurements and those taken 2 days after application. However, significant improvements were observed in the kinesio tape group, with regard to joint position sense, pain, kinesiophobia, symptoms, and functional limitations after treatment. Examination of the differences between pre- and post-treatment values in both groups revealed that the kinesio tape group demonstrated greater improvements compared to the placebo kinesio tape group. [Conclusion] Although short-term kinesio tape application did not increase hamstring muscle strength, it may have improved joint position sense, pain, kinesiophobia, symptoms, and daily limitations. PMID:27512259

  9. Standard and Short RoM Isokinetic Testing: Comparative Analysis in Identifying Submaximal Shoulder External Rotator Effort.

    PubMed

    Pujol, Eduard; Chaler, Joaquim; Sucarrats, Laura; López, Inés; Zeballos, Blanca; Garreta, Roser; Dvir, Zeevi

    2017-01-31

    An isokinetic-related parameter termed the difference between eccentric-concentric strength ratios at two distinct test velocities (DEC) based on 60° (standard) range of motion (RoM) has been proven to be highly efficient detecting feigned muscular efforts. This study aimed to verify whether a DEC derived from a much shorter test RoM (20°) was equally useful than a long RoM-derived one. Eighteen healthy men (32.4 ± 6.4 years old) took part in a study focusing on shoulder external rotation isokinetic strength. Participants performed a genuine shoulder external rotator maximal effort (eight pairs of concentric and eccentric contractions at high and low velocities at short and long RoM) and then instructed to feign maximal effort. Contraction velocities were adjusted accordingly by applying a 1:4 gradient and peak moments registered. Both condition DEC was then calculated by subtracting the eccentric and concentric strength ratios at low velocities from those at high velocities. DEC scores in the feigned effort were significantly higher than maximal effort ones in both conditions in men. It enabled the setting of specific cutoff levels for separating the efforts. Both approaches revealed a coincident sensitivity (78%) whereas short RoM showed an even higher specificity: 88% versus 78%. Thus, the short RoM protocol provides clinically acceptable detection power.

  10. Effect of kinesio taping on the isokinetic muscle function in football athletes with a knee injury.

    PubMed

    Hong, SoonKwon; Shim, JeMyung; Kim, SungJoong; Namkoong, Seung; Roh, HyoLyun

    2016-01-01

    [Purpose] The purpose of this study was to determine the difference in isokinetic muscle function in football athletes with a knee injury with and without kinesio taping. [Subjects] The subjects for this study were 10 football athletes (males) with a knee injury. [Methods] Measurements were performed by using Cybex dynamometer under uniform motion before and after the application of kinesio tape to the quadriceps and hamstring muscle. Maximal concentric knee extension and flexion at three angular velocities (60°/s, 120°/s, and 180°/s) were measured. [Results] A significant difference was found in peak torque and total work of the flexion at 120°/s and 180°/s, as well as in the average power of extension at 180°/s. [Conclusion] Though it is not the main therapy for muscle function in football athletes with injury, kinesio taping was an effective adjunct therapy.

  11. Effect of kinesio taping on the isokinetic muscle function in football athletes with a knee injury

    PubMed Central

    Hong, SoonKwon; Shim, JeMyung; Kim, SungJoong; Namkoong, Seung; Roh, HyoLyun

    2016-01-01

    [Purpose] The purpose of this study was to determine the difference in isokinetic muscle function in football athletes with a knee injury with and without kinesio taping. [Subjects] The subjects for this study were 10 football athletes (males) with a knee injury. [Methods] Measurements were performed by using Cybex dynamometer under uniform motion before and after the application of kinesio tape to the quadriceps and hamstring muscle. Maximal concentric knee extension and flexion at three angular velocities (60°/s, 120°/s, and 180°/s) were measured. [Results] A significant difference was found in peak torque and total work of the flexion at 120°/s and 180°/s, as well as in the average power of extension at 180°/s. [Conclusion] Though it is not the main therapy for muscle function in football athletes with injury, kinesio taping was an effective adjunct therapy. PMID:26957761

  12. Effect of creatine supplementation during rapid body mass reduction on metabolism and isokinetic muscle performance capacity.

    PubMed

    Oöpik, V; Pääsuke, M; Timpmann, S; Medijainen, L; Ereline, J; Smirnova, T

    1998-06-01

    Well-trained subjects (n = 6) were studied before and after losing a mean 3.0%-4.3% of body mass to determine whether muscle performance could be maintained or even enhanced by dietary creatine supplementation. During a 5-day period of loss of mass the subjects were randomly assigned to a creatine or placebo supplemented diet. All the subjects were measured before and after loss of mass on both supplements for isokinetic peak torque (PT) and work at peak torque (W(PT)) of knee extensors, also for intermittent high intensity working capacity of the same muscle group. The latter test consisted of submaximal isokinetic knee extensions at an angular velocity of 1.57 rad x s(-1) for 45 s at the rate of 30 contractions each min (submaximal work, Ws max) followed by 15-s maximal effort (maximal work, Wmax). Total duration of the test was 3 min. Haematocrit was measured and haemoglobin, ammonia, lactate, glucose and urea concentrations were analysed in blood samples obtained at rest and after cessation of muscle performance tests. The results indicated that creatine supplementation in comparison with placebo treatment during rapid body mass reduction may help to maintain muscle PT and W(PT)1 at high angular velocities, not influencing Wmax and the rate of fatigue development during Wmax, but affecting adversely Ws max. Within the limitations of the present study the reasons for the partially detrimental effect of creatine administration remain obscure, but it is suggested that impaired creatine uptake in muscle during body mass loss as well as creatine induced changes in muscle glucose and glycogen metabolism may be involved.

  13. Reduced muscle lengthening during eccentric contractions as a mechanism underpinning the repeated-bout effect.

    PubMed

    Lau, Wing Yin; Blazevich, Anthony J; Newton, Michael J; Wu, Sam Shi Xuan; Nosaka, Kazunori

    2015-05-15

    This study investigated biceps brachii distal myotendinous junction (MTJ) displacement during maximal eccentric elbow flexor contractions to test the hypothesis that muscle length change would be smaller (less MTJ displacement) during the second than the first exercise bout. Ten untrained men performed two eccentric exercise bouts (ECC1 and ECC2) with the same arm consisting of 10 sets of six maximal isokinetic (60°/s) eccentric elbow flexor contractions separated by 4 wk. Biceps brachii distal MTJ displacement was assessed using B-mode ultrasonography, and changes in the displacement (muscle length change) from the start to the end of each contraction during each set and over 10 sets were compared between bouts by two-way repeated-measures ANOVA. Several indirect muscle damage markers were also measured and compared between bouts by two-way repeated-measures ANOVA. The magnitude of MTJ displacement (average of six contractions) increased from set 1 (8.2 ± 4.7 mm) to set 10 (16.4 ± 4.7 mm) during ECC1 (P < 0.05), but no significant changes over sets were evident during ECC2 (set 1: 8.5 ± 4.0 mm; set 10: 9.3 ± 3.1 mm). Changes in maximal voluntary isometric contraction strength, range of motion, muscle thickness, ultrasound echo intensity, serum creatine kinase activity, and muscle soreness (visual analog scale) were smaller (P < 0.05) following ECC2 than ECC1, showing less damage in the repeated bout. These results indicate that the magnitude of muscle lengthening was less during the second than the first eccentric exercise bout, which appears to be a mechanism underpinning the repeated-bout effect. Copyright © 2015 the American Physiological Society.

  14. 21 CFR 890.1925 - Isokinetic testing and evaluation system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Isokinetic testing and evaluation system. 890.1925 Section 890.1925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices §...

  15. 21 CFR 890.1925 - Isokinetic testing and evaluation system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Isokinetic testing and evaluation system. 890.1925 Section 890.1925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices §...

  16. 21 CFR 890.1925 - Isokinetic testing and evaluation system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Isokinetic testing and evaluation system. 890.1925 Section 890.1925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices §...

  17. 21 CFR 890.1925 - Isokinetic testing and evaluation system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Isokinetic testing and evaluation system. 890.1925 Section 890.1925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices §...

  18. 21 CFR 890.1925 - Isokinetic testing and evaluation system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Isokinetic testing and evaluation system. 890.1925 Section 890.1925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices §...

  19. Effect of eccentric contraction velocity on muscle damage in repeated bouts of elbow flexor exercise.

    PubMed

    Barroso, Renato; Roschel, Hamilton; Ugrinowitsch, Carlos; Araújo, Rubens; Nosaka, Kazunori; Tricoli, Valmor

    2010-08-01

    Eccentric exercise induces muscle damage, but controversy exists concerning the effect of contraction velocity on the magnitude of muscle damage, and little is known about the effect of contraction velocity on the repeated-bout effect. This study examined slow (60 degrees.s(-1)) and fast (180 degrees.s(-1)) velocity eccentric exercises for changes in indirect markers of muscle damage following 3 exercise bouts that were performed every 2 weeks. Fifteen young men were divided into 2 groups based on the velocity of eccentric exercise: 7 in the Ecc60 (60 degrees.s(-1)) group, and 8 in the Ecc180 (180 degrees.s(-1)) group. The exercise consisted of 30 maximal eccentric contractions of the elbow flexors at each velocity, in which the elbow joint was forcibly extended from 60 degrees to 180 degrees (full extension) on an isokinetic dynamometer. Changes in maximal voluntary isometric contraction strength, range of motion, muscle soreness, and plasma creatine kinase activity before and for 4 days after the exercise were compared in the 2 groups using a mixed-model analysis (groupxboutxtime). No significant differences between groups were evident for changes in any variables following exercise bouts; however, the changes were significantly smaller (p<0.05) after the second and third bouts than after the first bout. These results indicate that the contraction velocity does not influence muscle damage or the repeated-bout effect.

  20. Isokinetic leg strength and power in elite handball players.

    PubMed

    González-Ravé, José M; Juárez, Daniel; Rubio-Arias, Jacobo A; Clemente-Suarez, Vicente J; Martinez-Valencia, María A; Abian-Vicen, Javier

    2014-06-28

    Isokinetic strength evaluation of the knee flexion and extension in concentric mode of contraction is an important part of the comprehensive evaluation of athletes. The aims of this study were to evaluate the isokinetic knee peak torque in both the extension and flexion movement in the dominant and non-dominant leg, and the relationship with jumping performance. Twelve elite male handball players from the top Spanish handball division voluntary participated in the study (age 27.68 ± 4.12 years; body mass 92.89 ± 12.34 kg; body height 1.90 ± 0.05 m). The knee extensor and flexor muscle peak torque of each leg were concentrically measured at 60º/s and 180º/s with an isokinetic dynamometer. The Squat Jump and Countermovement Jump were performed on a force platform to determine power and vertical jump height. Non-significant differences were observed between legs in the isokinetic knee extension (dominant= 2.91 ± 0.53 Nm/kg vs non-dominant = 2.70 ± 0.47 Nm/kg at 60º/s; dominant = 1.90 ± 0.31 Nm/kg vs non-dominant = 1.83 ± 0.29 Nm/kg at 180º/s) and flexion peak torques (dominant = 1.76 ± 0.29 Nm/kg vs non-dominant = 1.72 ± 0.39 Nm/kg at 60º/s; dominant = 1.30 ± 0.23 Nm/kg vs non-dominant = 1.27 ± 0.35 Nm/kg at 180º/s). Low and non-significant correlation coefficients were found between the isokinetic peak torques and vertical jumping performance (SJ = 31.21 ± 4.32 cm; CMJ = 35.89 ± 4.20 cm). Similar isokinetic strength was observed between the legs; therefore, no relationship was found between the isokinetic knee flexion and extension peak torques as well as vertical jumping performance in elite handball players.

  1. Isokinetic Leg Strength and Power in Elite Handball Players

    PubMed Central

    González-Ravé, José M.; Juárez, Daniel; Rubio-Arias, Jacobo A.; Clemente-Suarez, Vicente J; Martinez-Valencia, María A; Abian-Vicen, Javier

    2014-01-01

    Isokinetic strength evaluation of the knee flexion and extension in concentric mode of contraction is an important part of the comprehensive evaluation of athletes. The aims of this study were to evaluate the isokinetic knee peak torque in both the extension and flexion movement in the dominant and non-dominant leg, and the relationship with jumping performance. Twelve elite male handball players from the top Spanish handball division voluntary participated in the study (age 27.68 ± 4.12 years; body mass 92.89 ± 12.34 kg; body height 1.90 ± 0.05 m). The knee extensor and flexor muscle peak torque of each leg were concentrically measured at 60º/s and 180º/s with an isokinetic dynamometer. The Squat Jump and Countermovement Jump were performed on a force platform to determine power and vertical jump height. Non-significant differences were observed between legs in the isokinetic knee extension (dominant= 2.91 ± 0.53 Nm/kg vs non-dominant = 2.70 ± 0.47 Nm/kg at 60º/s; dominant = 1.90 ± 0.31 Nm/kg vs non-dominant = 1.83 ± 0.29 Nm/kg at 180º/s) and flexion peak torques (dominant = 1.76 ± 0.29 Nm/kg vs non-dominant = 1.72 ± 0.39 Nm/kg at 60º/s; dominant = 1.30 ± 0.23 Nm/kg vs non-dominant = 1.27 ± 0.35 Nm/kg at 180º/s). Low and non-significant correlation coefficients were found between the isokinetic peak torques and vertical jumping performance (SJ = 31.21 ± 4.32 cm; CMJ = 35.89 ± 4.20 cm). Similar isokinetic strength was observed between the legs; therefore, no relationship was found between the isokinetic knee flexion and extension peak torques as well as vertical jumping performance in elite handball players. PMID:25114749

  2. Changes in the Muscle Strength of the Elbow Flexors Following a Six-week Experimental Procedure in Adolescents Monitored Through Isokinetic and Motor Tests.

    PubMed

    Vuksanovic, Vladimir; Handjiski, Zoran; Handjiska, Eli

    2014-06-01

    A group of 7 subjects underwent an experimental procedure which studied the potential changes in the maximal strength of the non-dominant arm elbow flexors. The programme duration was limited to 6 weeks during which the subjects practiced exercises 3 times a week, 3 series, on a Scott bench. Individual approach was applied to the external load and it was designed so that the weight being lifted would increase if the number of lifts in one series would exceed 3. The subjects were monitored through the one-repetition maximum 1 RM motor test and the isokinetic tests performed on biodex system, tested in 3 time periods (at the beginning, after 3 weeks, and after the 6th week). Of the 6 isokinetic tests, only the test for the maximum torque and the time for achieving the maximum torque have shown statistically important changes in terms of reduction in values, which was not expected. The one-repetition maximum test, unlike the isokinetic tests, has shown statistically important increase of the maximal muscle strength of 32.1% after the third week of exercising, and 46.8% after the six weeks of exercising. The statistical test for the correlation between the two variables has shown low correlation between these two tests. The values of the data of the two test types have not shown any correspondence among the subjects possibly due to the type of performance of the maximal muscle load during exercises, performed in conditions identical to the one-repetition maximum test, with similar and yet different conditions in the case of isokinetic tests. Most probably, due to the conditions in which the exercises and the tests took place, there is difference in the obtained results.

  3. [Isokinetic profile of knee muscles in Tunisian competitive footballers].

    PubMed

    Ksibi, Imene; Kessomtini, Wassia; Ilehi, Youssef; Maaoui, Rim; Rahali Khachlouf, Hajer

    2015-05-01

    During football several joints are greatly demanded, especially the knees.The interest of the isokinetic is to detect an imbalance between agonist and antagonist muscles of the muscle leg and between dominant and non dominant leg, in order to prevent injuries and to improve the physical fitness of young soccer players. evaluate the isokinetic profile of flexor and extensor muscles of the knee of competitive footballers Methods : Prospective study conducted in the department of Physical and Rehabilitation Medicine of the Military Tunis Hospital, including 15 competitive footballers and evaluated during the month of August 2012. All patients underwent an isokinetic assessment of agonist and antagonist muscles of the knees in concentric mode 3 speed 60 ° / 120 ° and 180 ° (with analysis of figures and curves), using a Biodex dynamometer. The selected parameters were the time of maximum force (MFM) of the knee flexors and extensors, and the agonists / antagonists ratio (IJ / Q). The data were analyzed by SPSS software. 15 competitive footballers were included. The average age is 23.20 years ± 3.99 years, ranging from 18 to 28 years. The average size is 167.13 cm ± 3.6 cm with a range of 163 and 172 cm. The average weight is 60.87 kg ± 5.97 with a range of 50 to 70 kg. The isokinetic evaluation showed a statistically significant superiority of the flexor muscles of the right knee compared with those of the left knee at the speed 60 / s (p = 0.046) and 120 / s (p = 0.031), whereas this difference has not been found for the extensors muscles. The values of the ratio of quadriceps to hamstring increases with the speed of movement performed, the maximum moment / weight moving in the opposite direction. The isokinetic evaluation allows an objective assessment of the flexor and extensor muscles of the knee footballers, in order to correct imbalance and preserve the sporting future of the young footballers.

  4. Effects of Cold Water Immersion on Muscle Oxygenation During Repeated Bouts of Fatiguing Exercise

    PubMed Central

    Yeung, Simon S.; Ting, Kin Hung; Hon, Maurice; Fung, Natalie Y.; Choi, Manfi M.; Cheng, Juno C.; Yeung, Ella W.

    2016-01-01

    Abstract Postexercise cold water immersion has been advocated to athletes as a means of accelerating recovery and improving performance. Given the effects of cold water immersion on blood flow, evaluating in vivo changes in tissue oxygenation during cold water immersion may help further our understanding of this recovery modality. This study aimed to investigate the effects of cold water immersion on muscle oxygenation and performance during repeated bouts of fatiguing exercise in a group of healthy young adults. Twenty healthy subjects performed 2 fatiguing bouts of maximal dynamic knee extension and flexion contractions both concentrically on an isokinetic dynamometer with a 10-min recovery period in between. Subjects were randomly assigned to either a cold water immersion (treatment) or passive recovery (control) group. Changes in muscle oxygenation were monitored continuously using near-infrared spectroscopy. Muscle performance was measured with isokinetic dynamometry during each fatiguing bout. Skin temperature, heart rate, blood pressure, and muscle soreness ratings were also assessed. Repeated measures ANOVA analysis was used to evaluate treatment effects. The treatment group had a significantly lower mean heart rate and lower skin temperature compared to the control group (P < 0.05). Cold water immersion attenuated a reduction in tissue oxygenation in the second fatiguing bout by 4% when compared with control. Muscle soreness was rated lower 1 day post-testing (P < 0.05). However, cold water immersion had no significant effect on muscle performance in subsequent exercise. As the results show that cold water immersion attenuated decreased tissue oxygenation in subsequent exercise performance, the metabolic response to exercise after cold water immersion is worthy of further exploration. PMID:26735552

  5. Multiarticular isokinetic high-load eccentric training induces large increases in eccentric and concentric strength and jumping performance.

    PubMed

    Papadopoulos, Christos; Theodosiou, Konstantinos; Bogdanis, Gregory C; Gkantiraga, Evangelia; Gissis, Ioannis; Sambanis, Michalis; Souglis, Athanasios; Sotiropoulos, Aristomenis

    2014-09-01

    This study investigated the effects of short-term eccentric exercise training using a custom-made isokinetic leg press device, on concentric and eccentric strength and explosiveness as well as jumping performance. Nineteen healthy males were divided into an eccentric (ECC, n = 10) and a control group (CG, n = 9). The ECC group trained twice per week for 8 weeks using an isokinetic hydraulic leg press machine against progressively increasing resistance ranging from 70 to 90% of maximal eccentric force. Jumping performance and maximal force generating capacity were measured before and after eccentric training. In the ECC group, drop jump (DJ) height and maximal power were increased by 13.6 ± 3.2% (p < 0.01) and 25.8 ± 1.2% (p < 0.01), whereas ground contact time was decreased by 17.6 ± 2.6% (p < 0.01). Changes in ankle, knee, and hip joint angles were also reduced by 33.9 ± 1.1%, 31.1 ± 1.0%, and 32.4 ± 1.6% (all p < 0.01), respectively, indicating an increase in muscle stiffness during the DJ. Maximal eccentric and concentric leg press force was increased by 64.9 ± 5.5% (p < 0.01) and 32.2 ± 8.8% (p < 0.01), respectively, and explosiveness, measured as force attained in the first 300 milliseconds, was increased by 49.1 ± 4.8% (p < 0.01) and 77.1 ± 7.7% (p < 0.01), respectively. The CG did not show any statistically significant changes in all parameters measured. The main findings of this study were that maximal concentric and eccentric force, explosiveness, and DJ performance were markedly increased after only 16 training sessions, possibly because of the high eccentric load attained during the bilateral eccentric leg press exercise performed on this custom-made device.

  6. The effect of 8-weeks proprioceptive exercise program in postural sway and isokinetic strength of ankle sprains of Tunisian athletes.

    PubMed

    Ben Moussa Zouita, A; Majdoub, O; Ferchichi, H; Grandy, K; Dziri, C; Ben Salah, F Z

    2013-12-01

    Our objective is to investigate the effects of proprioceptive exercises rehabilitation on isokinetic strength and postural balance in athletes with sprain ankle. The ankles of 16 subjects were tested: eight in the functional instability (FI) group and eight non-injured (NI) subjects in the control group. Subjects were asked to take part in a testing session. The test order for the postural stability and isokinetic strength tests was randomized to avoid learning or fatigue effects. The testing session started with a 5-minute warm-up. Subjects were then instructed to perform several lower body flexibility exercises. The test procedure consisted in static assessments, where single-limb (right and left) stance postural stability was assessed. Three practice trials were allowed for each subject. The assessment quantifies postural sway velocity while the athlete stands calmly on one foot on the force plate, for each leg. They were asked to stand as still as possible for 30s, upper limbs along the body. The subjects were requested to maintain balance with eyes open and then with the eyes closed on the firm surface. The sway velocity (in degrees per second) is given for all trials. Subjects were allowed a 1-minute rest between tests. The regime of isokinetic evaluation of dorsi-plantar flexions is concentric, with three successive speeds: slow (30°/s, reps 5), average (60°/s, reps 10), and fast (120°/s, reps 15), according to the protocol established by European Group for the development and the isokinetic research and the procedural guidelines. Relative moment of strength and times of acceleration and deceleration were calculated for each set of isokinetic testing repetitions per body side, muscle group and testing speed. The results of tests-retest and between both groups (injured vs. healthy) show that after eight weeks of proprioceptive work, significant increase of maximal strength, decrease in times of acceleration and deceleration at the level of plantar flexors

  7. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity

    PubMed Central

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-01-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s-1, and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p < 0.05, Hedge’s g = 4.27). Both measures were highly associated (r = 0.83), and the 95% limits of agreement (LoA) represented 24.5% of TWWAnT. TWFAT of knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p < 0.05, g = 9.52). By contrast, both measures were not associated (r = 0.09), and the 95% LoA represented 31.1% of TWWAnT. Combining TWFAT of knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p < 0.05, g = 5.26), a moderate association (r = 0.65) and 95% LoA representing 25.5% of TWWAnT. We concluded that TWFAT of knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key points Total work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test). The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a

  8. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity.

    PubMed

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-03-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s(-1), and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p < 0.05, Hedge's g = 4.27). Both measures were highly associated (r = 0.83), and the 95% limits of agreement (LoA) represented 24.5% of TWWAnT. TWFAT of knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p < 0.05, g = 9.52). By contrast, both measures were not associated (r = 0.09), and the 95% LoA represented 31.1% of TWWAnT. Combining TWFAT of knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p < 0.05, g = 5.26), a moderate association (r = 0.65) and 95% LoA representing 25.5% of TWWAnT. We concluded that TWFAT of knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key pointsTotal work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test).The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a high

  9. Test-Retest Reliability of a Novel Isokinetic Squat Device With Strength-Trained Athletes.

    PubMed

    Bridgeman, Lee A; McGuigan, Michael R; Gill, Nicholas D; Dulson, Deborah K

    2016-11-01

    Bridgeman, LA, McGuigan, MR, Gill, ND, and Dulson, DK. Test-retest reliability of a novel isokinetic squat device with strength-trained athletes. J Strength Cond Res 30(11): 3261-3265, 2016-The aim of this study was to investigate the test-retest reliability of a novel multijoint isokinetic squat device. The subjects in this study were 10 strength-trained athletes. Each subject completed 3 maximal testing sessions to assess peak concentric and eccentric force (N) over a 3-week period using the Exerbotics squat device. Mean differences between eccentric and concentric force across the trials were calculated. Intraclass correlation coefficients (ICCs) and coefficients of variation (CVs) for the variables of interest were calculated using an excel reliability spreadsheet. Between trials 1 and 2 an 11.0 and 2.3% increase in mean concentric and eccentric forces, respectively, was reported. Between trials 2 and 3 a 1.35% increase in the mean concentric force production and a 1.4% increase in eccentric force production was reported. The mean concentric peak force CV and ICC across the 3 trials was 10% (7.6-15.4) and 0.95 (0.87-0.98) respectively. However, the mean eccentric peak force CV and ICC across the trials was 7.2% (5.5-11.1) and 0.90 (0.76-0.97), respectively. Based on these findings it is suggested that the Exerbotics squat device shows good test-retest reliability. Therefore practitioners and investigators may consider its use to monitor changes in concentric and eccentric peak force.

  10. Disturbed motor control of rhythmic movement at 2 h and delayed after maximal eccentric actions.

    PubMed

    Bottas, Reijo; Miettunen, Kari; Komi, Paavo V; Linnamo, Vesa

    2010-08-01

    The aim of this study was to examine the influence of exercise-induced muscle damage on elbow rhythmic movement (RM) performance and neural activity pattern and to investigate whether this influence is joint angle specific. Ten males performed an exercise of 50 maximal eccentric elbow flexions in isokinetic machine with duty cycle of 1:15. Maximal dynamic and isometric force tests (90 degrees , 110 degrees and 130 degrees elbow angle) and both active and passive stretch reflex tests of elbow flexors were applied to the elbow joint. The intentional RM was performed in the horizontal plane at elbow angles; 60-120 degrees (SA-RM), 80-140 degrees (MA-RM) and 100-160 degrees (LA-RM). All measurements together with the determination of muscle soreness, swelling, passive stiffness, serum creatine kinase were conducted before, immediately and 2h as well as 2 days, 4 days, 6 days and 8 days post-exercise. Repeated maximal eccentric actions modified the RM trajectory symmetry acutely (SA-RM) and delayed (SA/MA/LA-RM) until the entire follow up of 8 days. Acutely lowered MA-RM peak velocity together with reduced activity of biceps brachii (BB) at every RM range, reflected a poorer acceleration and deceleration capacity of elbow flexors. A large acute drop of BB EMG burst amplitude together with parallel decrease in BB active stretch reflex amplitude, especially 2h post-exercise, suggested an inhibitory effect originating most likely from groups III/IV mechano-nociceptors. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  11. Isokinetic neck strength profile of senior elite rugby union players.

    PubMed

    Olivier, Pierre E; Du Toit, David E

    2008-04-01

    To delineate and compare the isokinetic neck strength profile of senior elite rugby players. One hundred and eighty-nine rugby players (mean; 95% confidence intervals: 24.31; 23.87-24.75 years) were sampled from South African provincial teams and assessed anthropometrically and isokinetically according to a set protocol. Specially designed equipment was used to perform the isokinetic assessment and gathered data were analysed according to positional categories (front, second, back row and backline players). Second row forwards performed the best in the measure of peak flexion (44.04; 40.41-47.67Nm) and lateral flexion right (69.42; 63.36-75.48Nm) and left (66.31; 61.21-71.41Nm) torque, while the front row forwards performed best in peak extension torque (65.60; 62.12-69.08Nm). Few significant differences (p<0.05) existed between the forward positional categories. However, they all proved to be significantly (p<0.05) stronger and more powerful than the backline players. Peak torque values relative to body weight indicated much less variability between all positional categories. Cervical flexor to extensor ratios showed that front row forwards (65; 61.94-68.06%) had significantly (p<0.05) lower ratios than the other positional categories. Absolute peak torque is an important positional prerequisite, especially among the front row forwards. Isokinetic neck strength data presented here provides a benchmark for the effective and quantified comparison of neck strength variables, assisting with preparticipation screening and the effective rehabilitation of injured senior rugby union players.

  12. Isokinetic profile of wrist and forearm strength in elite female junior tennis players

    PubMed Central

    Ellenbecker, T S; Roetert, E P; Riewald, S

    2006-01-01

    Background In tennis, injuries to the elbow and wrist occur secondary to the repetitive nature of play and are seen at increasingly young ages. Isokinetic testing can be used to determine muscular strength levels, but dominant/non‐dominant and agonist/antagonist relations are needed for meaningful interpretation of the results. Objectives To determine whether there are laterality differences in wrist extension/flexion (E/F) and forearm supination/pronation (S/P) strength in elite female tennis players. Methods 32 elite female tennis players (age 12 to 16 years) with no history of upper extremity injury underwent bilateral isokinetic testing using a Cybex 6000 dynamometer. Peak torque and single repetition work values for wrist E/F and forearm S/P were measured at speeds of 90°/s and 210°/s, with random determination of the starting extremity. Repeated measures analysis of variance was used to determine differences between extremities for peak torque and single repetition work values. Results Significantly greater (p<0.01) dominant arm wrist E/F and forearm pronation strength was measured at both testing speeds. Significantly less (p<0.01) dominant side forearm supination strength was measured at both testing speeds. Conclusions Greater dominant arm wrist E/F and forearm pronation strength is common and normal in young elite level female tennis players. These strength relations indicate sport specific muscular adaptations in the dominant tennis playing extremity. The results of this study can guide clinicians who work with young athletes from this population. Restoring greater dominant side wrist and forearm strength is indicated after an injury to the dominant upper extremity in such players. PMID:16632571

  13. Isokinetic Scapular Muscle Performance in Overhead Athletes With and Without Impingement Symptoms.

    PubMed

    Cools, Ann M; Witvrouw, Erik E; Mahieu, Nele N; Danneels, Lieven A

    2005-06-01

    Context: Overhead activities such as throwing, tennis, or volleyball place athletes at considerable risk for overuse injuries. A relationship between scapulothoracic muscle imbalance and shoulder pain has been suggested.Objective: To compare the isokinetic muscle performance of the scapular muscles between overhead athletes with impingement symptoms and uninjured overhead athletes and to identify strength deficits in the patient population.Design: A repeated-measures analysis of variance with 1 within-subjects factor (side) and 1 between-subjects factor (group) was used to compare strength values and agonist:antagonist ratios across sides and across groups.Setting: University laboratory.Patients or Other Participants: Thirty overhead athletes with chronic shoulder impingement symptoms and 30 overhead athletes without a history of shoulder pain.Intervention(s): A linear protraction-retraction movement in the scapular plane at 2 velocities (12.2 cm/s and 36.6 cm/s).Main Outcome Measure(s): Isokinetic strength values and protraction:retraction ratios for both velocities.Results: Overhead athletes with impingement symptoms showed decreased force output:body weight at both velocities in the protractor muscles on the injured side compared with the uninjured side (-13.7% at slow velocity, -15.5% at high velocity) and compared with the control group at high velocity (-20.7%). On both sides, the patient group had significantly lower protraction:retraction ratios than the control group, measured at slow velocity (nondominant = -11%, dominant = -13.7%).Conclusions: Overhead athletes with impingement symptoms demonstrated strength deficits and muscular imbalance in the scapular muscles compared with uninjured athletes.

  14. Effects of Isokinetic Strength Training on Walking in Persons With Stroke: A Double-blind Controlled Pilot Study

    PubMed Central

    Kim, C. Maria; Eng, Janice J.; MacIntyre, Donna L.; Dawson, Andrew S.

    2012-01-01

    Objectives The goal most often stated by persons with stroke is improved walking function. The purpose of this study was to determine the effects of isokinetic strength training on walking performance, muscle strength, and health-related quality of life in survivors of chronic stroke. Methods Twenty participants (age, 61.2 ± 8.4 years) with chronic stroke were randomized into 2 groups. The experimental group undertook maximal concentric isokinetic strength training, whereas the control group received passive range of motion of the paretic lower extremity 3 times a week for 6 weeks. The Kin-Com Isokinetic Dynamometer (Chattanooga Group Inc., TN) was used for both the strengthening and passive range of motion exercises. The Mann-Whitney U test was used to compare the changes in scores (postintervention minus baseline) between the control and experimental groups for a composite lower extremity strength score, walking speed (level-walking and stair-walking) and health-related quality of life measure (36-Item Short Form Health Survey [SF-36]). Results Both the experimental and control groups increased their strength and walking speed postintervention; however, there were no differences in the changes in walking speed between the groups. There was a trend (P = .06) toward greater strength improvement in the experimental group compared with the control group. No changes in SF-36 scores were found in either group. Conclusions Intervention aimed at increasing strength did not result in improvements in walking. The results of this study stress the importance of controlled clinical trials in determining the effect of specific treatment approaches. Strength training in conjunction with other task-related training may be indicated. PMID:17903837

  15. A comparison of wrist isokinetic muscle strength in wheelchair table tennis and wheelchair basketball players

    PubMed Central

    Akınoğlu, Bihter; Kocahan, Tuğba; Yıldırım, Necmiye Ün; Soylu, Çağlar; Apur, Ufuk; Hasanoğlu, Adnan

    2017-01-01

    Aim: The aim of this study was to compare isokinetic muscle strength of wrist flexor and extensor muscles in paralympic athletes. Methods: This study was carried out with the participation of 9 (4 females and 5 males) wheelchair (WC) table tennis players aged 24+3 and 8 male WC basketball players aged 26+3, met the criteria and voluntarly participate in the study. Body weight, height, body mass index and dominant extremity of the study subjects were recorded. İsokinetic measurement were performed with Isomed 2000® device. İsokinetic testing protocol; before the test all players performed the wrist flexion and extension isokinetic test with the 5 repeating at 90º/sec as a warm-up and comprehending the test. Then, wrist flexion and extension concentric-concentric strength measurements were performed with the 5 repeating at 60º/sec and with the 15 repeating at 240º/sec with the angle between 50 degrees of wrist flexion and 60 degrees of wrist extension and peak torque, peak torque/kg values and flexion/extension ratios were recorded. Mann-Whitney U test was used to compare isokinetic muscle strength quantitative variables in athletes. Findings: Isokinetic muscle strength of wrist flexors and extensors was higher in both sides in WC table tennis players with 60º/sec speed (p<0,05). İsokinetic muscle strength of wrist flexors and extensors was higher in both sides in WC basketball players with 240º/sec speed (p<0,05). There was no significant difference statistically between the groups in isokinetic wrist flexion and extansion peak torque/kg ratio in all speeds (p>0,05). Wrist flexion/extension peak torque ratios were similar in both groups. When examining the athletes flexion/extension ratios, wrist extensor muscles were weaker than flexor muscles and flexor muscles were average twice stronger than extensor muscles in both sports (Table1). Table 1. Comparison of wrist flexion and extension isokinetic muscle strength, peak torque/kg and agonist/antagonist ratio

  16. Effects of Cold Water Immersion on Muscle Oxygenation During Repeated Bouts of Fatiguing Exercise: A Randomized Controlled Study.

    PubMed

    Yeung, Simon S; Ting, Kin Hung; Hon, Maurice; Fung, Natalie Y; Choi, Manfi M; Cheng, Juno C; Yeung, Ella W

    2016-01-01

    Postexercise cold water immersion has been advocated to athletes as a means of accelerating recovery and improving performance. Given the effects of cold water immersion on blood flow, evaluating in vivo changes in tissue oxygenation during cold water immersion may help further our understanding of this recovery modality. This study aimed to investigate the effects of cold water immersion on muscle oxygenation and performance during repeated bouts of fatiguing exercise in a group of healthy young adults. Twenty healthy subjects performed 2 fatiguing bouts of maximal dynamic knee extension and flexion contractions both concentrically on an isokinetic dynamometer with a 10-min recovery period in between. Subjects were randomly assigned to either a cold water immersion (treatment) or passive recovery (control) group. Changes in muscle oxygenation were monitored continuously using near-infrared spectroscopy. Muscle performance was measured with isokinetic dynamometry during each fatiguing bout. Skin temperature, heart rate, blood pressure, and muscle soreness ratings were also assessed. Repeated measures ANOVA analysis was used to evaluate treatment effects. The treatment group had a significantly lower mean heart rate and lower skin temperature compared to the control group (P < 0.05). Cold water immersion attenuated a reduction in tissue oxygenation in the second fatiguing bout by 4% when compared with control. Muscle soreness was rated lower 1 day post-testing (P < 0.05). However, cold water immersion had no significant effect on muscle performance in subsequent exercise. As the results show that cold water immersion attenuated decreased tissue oxygenation in subsequent exercise performance, the metabolic response to exercise after cold water immersion is worthy of further exploration.

  17. A randomized trial of isokinetic versus isotonic rehabilitation program after arthroscopic meniscectomy.

    PubMed

    Koutras, Georgios; Letsi, Magdalini; Papadopoulos, Pericles; Gigis, Ioannis; Pappas, Evangelos

    2012-02-01

    Although both isotonic and isokinetic exercises are commonly used in the rehabilitation of patients after arthroscopic meniscectomy no studies have compared their effect on strength recovery and functional outcomes. The purpose of this study was to investigate the effects of two rehabilitation programs (isotonic and isokinetic) on muscle strength and functional performance after partial knee meniscectomy. A secondary purpose was to assess the correlation between isokinetic strength deficits and hop test performance deficits. Twenty male patients who underwent arthroscopic partial meniscectomy volunteered for the study. Both isotonic and isokinetic training were performed with the same equipment thereby blinding subjects to the mode of exercise. Main outcome measures were collected on the 14th and 33rd postoperative days and included isokinetic strength of the knee extensors and flexors, functional performance (single, triple, and vertical hopping) and the Lysholm questionnaire. Multivariate and univariate analyses of variance were used to assess the effects of the independent variables on the isokinetic variables, functional tests, and Lysholm score. Pearson's correlation was used to assess the relationship between isokinetic strength deficits and functional performance deficits. Isokinetic measures, functional tests, and the Lysholm score all increased between initial and final assessment (p≤0.003). However, there were no group or group*time effects on any of the outcome variables (p≥0.33). Functional tests were better predictors of isokinetic deficits in the 14(th) compared to the 33(rd) postoperative day. No differences were found in the outcomes of patients treated using an isokinetic and an isotonic protocol for rehabilitation after arthroscopic meniscectomy. More than half of patients did not meet the 90% criterion in the hop tests for safe return to sports five weeks after meniscectomy. There were correlations between the hop tests and isokinetic

  18. A RANDOMIZED TRIAL OF ISOKINETIC VERSUS ISOTONIC REHABILITATION PROGRAM AFTER ARTHROSCOPIC MENISCECTOMY

    PubMed Central

    Koutras, Georgios; Letsi, Magdalini; Papadopoulos, Pericles; Gigis, Ioannis

    2012-01-01

    Background: Although both isotonic and isokinetic exercises are commonly used in the rehabilitation of patients after arthroscopic meniscectomy no studies have compared their effect on strength recovery and functional outcomes. Purpose: The purpose of this study was to investigate the effects of two rehabilitation programs (isotonic and isokinetic) on muscle strength and functional performance after partial knee meniscectomy. A secondary purpose was to assess the correlation between isokinetic strength deficits and hop test performance deficits. Methods: Twenty male patients who underwent arthroscopic partial meniscectomy volunteered for the study. Both isotonic and isokinetic training were performed with the same equipment thereby blinding subjects to the mode of exercise. Main outcome measures were collected on the 14th and 33rd postoperative days and included isokinetic strength of the knee extensors and flexors, functional performance (single, triple, and vertical hopping) and the Lysholm questionnaire. Multivariate and univariate analyses of variance were used to assess the effects of the independent variables on the isokinetic variables, functional tests, and Lysholm score. Pearson's correlation was used to assess the relationship between isokinetic strength deficits and functional performance deficits. Results: Isokinetic measures, functional tests, and the Lysholm score all increased between initial and final assessment (p≤0.003). However, there were no group or group*time effects on any of the outcome variables (p≥0.33). Functional tests were better predictors of isokinetic deficits in the 14th compared to the 33rd postoperative day. Conclusion: No differences were found in the outcomes of patients treated using an isokinetic and an isotonic protocol for rehabilitation after arthroscopic meniscectomy. More than half of patients did not meet the 90% criterion in the hop tests for safe return to sports five weeks after meniscectomy. There were

  19. Isokinetic evaluation after two-stage bicruciate reconstruction

    PubMed Central

    GiglioTakaes, Igor; Inada, Mauro Mituso; de Miranda, João Batista; Cunha, Sérgio Augusto; Piedade, Sérgio Rocha

    2014-01-01

    Objective: To assess the functional balance of the knee after bicruciate reconstruction and its correlation with clinical score. Methods: 14 patients (11 men and three women), mean age 29.9±7.65 years, mean BMI 26.2±2.51 kg/m2 underwent surgical reconstruction of the Posterior Cruciate Ligament (PCL) and Anterior Cruciate Ligament (ACL) in two stages, with a mean interval of 3 months between procedures. With a mean follow-up period of 27.33 months, the isokinetic knee analysis was performed at 60°/s and 180°/s and the Lysholm and Tegner scores were applied. Results: The Lysholm score was 86.8±11.1 points and the Tegner score showed a deficit of 30% compared to pre-injury level. In isokinetic evaluation, the deficit of the operated quadriceps average torque was 17.05% at 60°/s and 12.16% at 180°/s, while the average flexor torque deficit was 3.43% at 60°/s and 5.82% at 180°/s. Although it was observed torque deficit between members, there were no statistical differences regarding the functional balance between hamstrings and quadriceps. Conclusion: Although the results of isokinetic evaluation has shown a functional balance of the knee (flexor-extensor), which may have contributed to the good subjective Lysholm score in the bicruciate two-stage reconstruction, two-stage reconstruction did not restore the pre-injury functional level. Level of Evidence IV, Case Series. PMID:24644415

  20. Properties of Isokinetic Fatigue at Various Movement Speeds in Adult Males.

    ERIC Educational Resources Information Center

    Clarke, David H.; Manning, James M.

    1985-01-01

    Eighteen male subjects, aged 20 to 28 years, engaged in three fatigue bouts using an isokinetic dynamometer to measure knee extension contractions. Peak torque varied inversely with movement speed, and the pattern of decrement was independent of speed. Time to peak torque did not change significantly across trials in isokinetic fatigue. (Author/MT)

  1. Properties of Isokinetic Fatigue at Various Movement Speeds in Adult Males.

    ERIC Educational Resources Information Center

    Clarke, David H.; Manning, James M.

    1985-01-01

    Eighteen male subjects, aged 20 to 28 years, engaged in three fatigue bouts using an isokinetic dynamometer to measure knee extension contractions. Peak torque varied inversely with movement speed, and the pattern of decrement was independent of speed. Time to peak torque did not change significantly across trials in isokinetic fatigue. (Author/MT)

  2. [Study and evaluation of patients with obliterating arteriopathy of the lower limbs: use of isokinetics to analyze muscular strength and fatigue].

    PubMed

    Demonty, B; Detaille, V; Pasquier, A-Y

    2004-11-01

    The aim of the study was to evaluate strength of the dorsal and plantar flexors in patients with obliterating arteriopathy of the lower limbs (stage 2) and to evaluate fatigue. The comparison was based on two groups of ten patients: one with obliterating arteriopathy, and the second with healthy limbs as a control group. Each group of patients underwent bilateral plantar flexion and dorsiflexion of the ankle on an isokinetic machine, with the following movements: three series of five movements at 120 degrees/s, then three series of three movements at 30 degrees/s in a concentric mode to evaluate strength. The exercise was repeated 20 times at 180 degrees/s to evaluate fatigue. The isokinetic parameters selected were the couple peak and ratio of workload to total weight of the patient. Tests controlled for cardiac frequency, as measured by electrocardiography, and blood pressure. Patients with obliterating arteriopathy of the lower limbs were generally weaker in global strength of plantar and dorsal flexors and had greater muscular fatigue than the control group (P < 0.05). Decreased performance in the leg muscles in patients with obliterating arteriopathy of the lower limbs is likely due to arterial deficit. Muscular metabolism anomalies such dysfunction of the terminal stages of the oxidative phosphorylation could also affect strength. Use of isokinetics represents an interesting possibility for treatment of patients with multiple cardiovascular abnormalities.

  3. Isokinetic trunk-strength deficits in people with and without low-back pain: a comparative study with consideration of effort.

    PubMed

    Reid, S; Hazard, R G; Fenwick, J W

    1991-03-01

    The purposes of this study were to determine (a) the degree and distribution of isokinetic trunk strength deficits in people with chronic low-back pain (CLBP) and (b) to what degree subject effort during testing affects those deficits. We measured the isokinetic trunk strengths of three subject groups on the Cybex Trunk Extension/Flexion machine. Groups 1 and 2 consisted of 155 men and women with CLBP who were divided into maximal (n = 115) and submaximal (n = 40) groups according to their torque/position curve variability. Group 3 was made up of 32 back-healthy men and women who served as controls. The results demonstrated that men had higher flexion and extension torques than women did for all groups. The control group had higher flexion and extension torques than the maximal-effort CLBP group did. The extensors had a proportionally greater deficit than the flexors did in this LBP group. Comparing the two groups with CLBP, the maximal-effort group had higher flexion and extension torques than the submaximal effort group did, and the extensors showed a greater deficit. Degree of effort during testing does affect the results. Therapists should consider extensor strengthening and reeducation exercises when designing exercise programs to restore normal function in people with chronic CLBP.

  4. Functional isokinetic strength ratios in baseball players with injured elbows.

    PubMed

    Lin, Yin-Chou; Thompson, Angela; Kung, Jung-Tang; Chieh, Liang-Wei; Chou, Shih-Wei; Lin, Jung-Charng

    2010-02-01

    Elbow injuries are widely reported among baseball players. The elbow is susceptible to injury when elbow-flexor and -extensor forces are imbalanced during pitching or throwing. Assessment of muscle-strength ratios may prove useful for diagnosing elbow injury. The purpose of this study was to assess the relationship between the elbow-flexor and -extensor functional isokinetic ratios and elbow injury in baseball players. Retrospective study. Biomechanics laboratory. College baseball players with (n = 9) and without (n = 12) self-reported elbow pain or loss of strength were recruited. Trials were conducted using a dynamometer to assess dominant-arm flexor and extensor concentric and eccentric strength at angular velocities of 60 degrees and 240 degrees/s. Functional isokinetic ratios were calculated and compared between groups. Regression analysis revealed that a ratio of biceps concentric to triceps concentric strength greater than 0.76 (the median value) significantly predicted elbow injury (P = .01, odds ratio of injury = 24). No other ratios or variables (including position played) were predictive of injury status. These findings suggest that the ratio of biceps concentric to triceps concentric functional strength strongly predicts elbow-injury status in baseball players. Assessment of this ratio may prove useful in a practical setting for training purposes and both injury diagnosis and rehabilitation.

  5. Offset of rotation centers creates a bias in isokinetics: a virtual model including stiffness or friction.

    PubMed

    Deslandes, Samuel; Mariot, Jean-Pierre; Serveto, Sébastien

    2008-07-19

    The present paper deals with a virtual model devoted to isokinetics and isometrics assessment of a human muscular group in the common joints, knee, ankle, hip, shoulder, cervical spine, etc. This virtual model with an analytical analysis followed by a numerical simulation is able to predict measurement errors of the joint torque due to offset of rotation centers between the body segment and the ergometer arm. As soon as offset is present, errors increase due to the influence of inertial effects, gravity effects, stiffness due to the limb strapping on the ergometer arm or Coulomb friction between limb and ergometer. The analytical model is written in terms of Lagrange formalism and the numerical model uses ADAMS software adapted to multi-body dynamics simulations. Results of models show a maximal relative error of 11%, for a 10% relative offset between the rotation centers. Inertial contributions are found to be negligible but gravity effects must be discussed in regard to the measured torque. Stiffness or friction effects may also increase the torque error; in particular when offset occurs, it is shown that errors due to friction have to be considered for all torque level while only stiffness effects have to be considered for torque less than 25Nm. This study also emphasizes the influence of the angular range of motion at a given angular position.

  6. A ground-based comparison of the Muscle Atrophy Research and Exercise System (MARES) and a commercially available isokinetic dynamometer

    NASA Astrophysics Data System (ADS)

    English, Kirk L.; Hackney, Kyle J.; De Witt, John K.; Ploutz-Snyder, Robert J.; Goetchius, Elizabeth L.; Ploutz-Snyder, Lori L.

    2013-11-01

    IntroductionInternational Space Station (ISS) crewmembers perform muscle strength and endurance testing pre- and postflight to assess the physiologic adaptations associated with long-duration exposure to microgravity. However, a reliable and standardized method to document strength changes in-flight has not been established. To address this issue, a proprietary dynamometer, the Muscle Atrophy Research and Exercise System (MARES) has been developed and flown aboard the ISS. The aims of this ground-based investigation were to: (1) evaluate the test-retest reliability of MARES and (2) determine its agreement with a commercially available isokinetic dynamometer previously used for pre- and postflight medical testing. MethodsSix males (179.5±4.7 cm; 82.0±8.7 kg; 31.3±4.0 yr) and four females (163.2±7.3 cm; 63.2±1.9 kg; 32.3±6.8 yr) completed two testing sessions on a HUMAC NORM isokinetic dynamometer (NORM) and two sessions on MARES using a randomized, counterbalanced, cross-over design. Peak torque values at 60° and 180° s-1 were calculated from five maximal repetitions of knee extension (KE) and knee flexion (KF) for each session. Total work at 180° s-1 was determined from the area under the torque versus displacement curve during 20 maximal repetitions of KE and KF. ResultsIntraclass correlation coefficients were relatively high for both devices (0.90-0.99). Only one dependent measure, KE peak torque at 60° s-1 exhibited good concordance between devices (ρ=0.92) and a small average difference (0.9±17.3 N m). ConclusionMARES demonstrated acceptable test-retest reliability and thus should serve as a good tool to monitor in-flight strength changes. However, due to poor agreement with NORM, it is not advisable to compare absolute values obtained on these devices.

  7. The effect of beta-alanine supplementation on isokinetic force and cycling performance in highly trained cyclists.

    PubMed

    Howe, Samuel T; Bellinger, Phillip M; Driller, Matthew W; Shing, Cecilia M; Fell, James W

    2013-12-01

    Beta-alanine may benefit short-duration, high-intensity exercise performance. The aim of this randomized double-blind placebo-controlled study was to examine the effects of beta-alanine supplementation on aspects of muscular performance in highly trained cyclists. Sixteen highly trained cyclists (mean ± SD; age = 24 ± 7 yr; mass = 70 ± 7 kg; VO2max = 67 ± 4 ml · kg(-1) · min(-1)) supplemented with either beta-alanine (n = 8, 65 mg · kg - 1BM) or a placebo (n = 8; dextrose monohydrate) over 4 weeks. Pre- and postsupplementation cyclists performed a 4-minute maximal cycling test to measure average power and 30 reciprocal maximal isokinetic knee contractions at a fixed angular velocity of 180° · sec(-1) to measure average power/repetition, total work done (TWD), and fatigue index (%). Blood pH, lactate (La-) and bicarbonate (HCO3-) concentrations were measured pre- and postisokinetic testing at baseline and following the supplementation period. Beta-alanine supplementation was 44% likely to increase average power output during the 4-minute cycling time trial when compared with the placebo, although this was not statistically significant (p = .25). Isokinetic average power/repetition was significantly increased post beta-alanine supplementation compared with placebo (beta-alanine: 6.8 ± 9.9 W, placebo: -4.3 ± 9.5 W, p = .04, 85% likely benefit), while fatigue index was significantly reduced (p = .03, 95% likely benefit). TWD was 89% likely to be improved following beta-alanine supplementation; however, this was not statistically significant (p = .09). There were no significant differences in blood pH, lactate, and HCO3- between groups (p > .05). Four weeks of beta-alanine supplementation resulted in worthwhile changes in time-trial performance and short-duration muscular force production in highly trained cyclists.

  8. A Ground-Based Comparison of the Muscle Atrophy Research and Exercise System (MARES) and a Standard Isokinetic Dynamometer

    NASA Technical Reports Server (NTRS)

    Hackney, K. J.; English, K. L.; Redd, E.; DeWitt, J. K.; Ploutz-Snyder, R.; Ploutz-Snyder, L. L.

    2010-01-01

    PURPOSE: 1) To compare the test-to-test reliability of Muscle Atrophy Research and Exercise System (MARES) with a standard laboratory isokinetic dynamometer (ISOK DYN) and; 2) to determine if measures of peak torque and total work differ between devices. METHODS: Ten subjects (6M, 4F) completed two trials on both MARES and an ISOK DYN in a counterbalanced order. Peak torque values at 60 deg & 180 deg / s were obtained from five maximal repetitions of knee extension (KE) and knee flexion (KF). Total work at 180 deg / s was determined from the area under the torque vs. displacement curve during twenty maximal repetitions of KE and KF. Reliability of measures within devices was interpreted from the intraclass correlation coefficient (ICC) and compared between devices using the ratio of the within-device standard deviations. Indicators of agreement for the two devices were evaluated from: 1) a calculation of concordance (rho) and; 2) the correlation between the mean of measures versus the delta difference between measures (m u vs delta). RESULTS: For all outcome measures ICCs were high for both the ISOK DYN (0.95-0.99) and MARES (0.90-0.99). However, ratios of the within-device standard deviation were 1.3 to 4.3 times higher on MARES. On average, a wide range (3.3 to 1054 Nm) of differences existed between the values obtained. Only KE peak torque measured at 60 deg & 180 deg / s showed similarities between devices (rho = 0.91 & 0.87; Pearson's r for m u vs delta = -0.22 & -0.37, respectively). CONCLUSION: Although MARES was designed for use in microgravity it was quite reliable during ground-based testing. However, MARES was consistently more variable than an ISOK DYN. Future longitudinal studies evaluating a change in isokinetic peak torque or total work should be limited within one device.

  9. Piroxicam fails to reduce myocellular enzyme leakage and delayed onset muscle soreness induced by isokinetic eccentric exercise

    PubMed Central

    Croisier, J-L.; Monfils, T.; Deby-Dupon, G.; Fafchamps, M.; Venneman, I.; Crielaard, J-M.; Juchmès-Ferir, A.; Lhermerout, C.; Lamy, M.; Deby, C.

    1996-01-01

    To test the hypothesis that delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of prostaglandin E2 (PGE2), ten healthy male subjects were studied. Using a double-blind randomized crossover design, each subject performed two isokinetic tests separated by a period of at least 6 weeks: once with placebo, and once with piroxicam (Feldene®). They were given one capsule containing either placebo or piroxicam (20 mg) per day for 6 days with initial doses given starting 3 days prior to isokinetic testing. Exercise consisted of eight stages of five maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases, on a Kin Trex device at 60°/s angular velocity. The subjective presence and intensity of DOMS were evaluated using a visual analogue scale immediately after, and 24 and 48 h after each test. The mean plasma concentration of PGE2 measured at rest and after exercise was significantly lower in the group treated with piroxicam (p < 0.05). However, statistical analysis (two-way ANOVA test) revealed that exercise did not cause any significant change of mean plasma PGE2 over time in either of the two groups. Eccentric work was followed by severe muscle pain in extensor and flexor muscle groups. Maximal soreness was noted 48 h postexercise. Serum creatine kinase activity and the serum concentration of myoglobin increased significantly, and reached peak values 48 h after exercise in both experimental conditions (p < 0.001). By paired t-test, it appeared that there were no significant differences in the serum levels of these two markers of muscle damage between the two groups at any time point. We conclude that: (1) oral administration of piroxicam fails to reduce muscle damage and DOMS caused by strenuous eccentric exercise; and (2) the hypothetical role of increased PGE2 production in eccentric exercise-induced muscle damage, DOMS, and reduced isokinetic

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

    PubMed

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

    1996-01-01

    To address the question of whether delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of the arachidonic acid derived product prostaglandin E2 (PGE2). 10 healthy male subjects were submitted to eccentric and concentric isokinetic exercises on a Kin Trex device at 60 degrees/s angular velocity. Exercise consisted of 8 stages of 5 maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases. There was an interval of at least 30 days between eccentric and concentric testing, and the order of the two exercise sessions was randomly assigned. The subjective presence and intensity of DOMS was evaluated using a visual analogue scale, immediately, following 24 h and 48 h after each test. Five blood samples were drawn from an antecubital vein: at rest before exercise, immediately after, after 30 min recovery, 24 h and 48 h after the tests. The magnitude of the acute inflammatory response to exercise was assessed by measuring plasma levels of polymorphonuclear elastase ([EL]), myeloperoxidase ([MPO]) and PGE2 ([PGE2]). Using two way analysis of variance, it appeared that only eccentric exercise significantly increased [EL] and DOMS, especially of the hamstring muscles. Furthermore, a significant decrease in eccentric peak torque of this muscle group only was observed on day 2 after eccentric work (- 21%; P < 0.002). Serum activity of creatine kinase and serum concentration of myoglobin increased significantly 24 and 48 h after both exercise tests. However, these variables reached significantly higher values following eccentric contractions 48 h after exercise. Mean [PGE2] in the two exercise modes remained unchanged over time and were practically equal at each time point. On the basis of these findings, we conclude that the magnitude of polymorphonuclear (PMN) activation, muscle damage, and DOMS are greater after eccentric than after concentric muscle

  11. [Isokinetic profile of knee flexors and extensors in a population of rugby players].

    PubMed

    Larrat, E; Kemoun, G; Carette, P; Teffaha, D; Dugue, B

    2007-06-01

    We aimed to assess the isokinetic profile of the flexor and extensor muscles of the knee within a population of rugby players. This was a descriptive study. The rugby players underwent bilateral isokinetic assessment of knee flexion and extension on a CON-TREX MJ isokinetic dynamometer functioning at four angular frequencies - 90, 120, 180 and 240 degrees/s - in a concentric manner. The isokinetic parameters were peak torque, mean power, and mean work in relation to weight and femoral bicep: quadriceps ratio. The population included 16 "Federal 1" (semi-professional) rugby players with mean age 25 years (range 20-33 years). The players were divided into two groups: "forward" players (props, hookers, second line, third line) and "back" players (scrum, inside, center, wing, tail). The values of the isokinetic parameters did not reveal use of a preferred limb. Consequently, peak torque and mean power were higher in forward players than back players, whereas back players showed a higher relative power throughout the isokinetic test. Among rugby players, forward and back players showed differences in several isokinetic parameters. Accurate knowledge of the equilibrium between the knee's effector muscles is important for stability of the joint, to not only minimize articular accidents but also pinpoint force imbalances, thereby preventing muscular lesions during the sports season.

  12. Biomechanical comparison of isokinetic lifting and free lifting when applied to chronic low back pain rehabilitation.

    PubMed

    Bouilland, S; Loslever, P; Lepoutre, F X

    2002-03-01

    The study compares free and isokinetic lifting using a multivariate statistical analysis. Each of the 13 male subjects performed three free lifts and three isokinetic lifts using a CYBEX LIFTASK. The measurement variables were obtained from a 3D video system, two force plates and two strain-gauge transducers. Coupling of fuzzy space-time windowing and multiple correspondence analysis was used to show the links between the variables and the differences between the experimental situations. Isokinetic lifting had almost no points in common with free-lifting, but there was a similar range of extension for the different joints. Most free-lifting strategies could not be used in isokinetic lifting, as constraints between the subject and his environment were different. The main drawback of the isokinetic lifting was due to the necessity for individuals to reach the machine speed, yielding high transient efforts. The maximum vertical effort at the L5/S1 joint was about 1600, 1500 and 1400N for low, medium and high speed, whereas it was lower than 1300N, irrespective of the load, during free lifting. In the context of chronic low back pain rehabilitation, movement strategies used in free lifting could not be relearnt using an isokinetic machine. A better understanding of the common points and differences between isokinetic movement and free movement could help rehabilitation physicians to plan rehabilitation programmes, taking advantage of each kind of movement.

  13. Algorithms and novel applications based on the isokinetic ensemble. I. Biophysical and path integral molecular dynamics

    NASA Astrophysics Data System (ADS)

    Minary, Peter; Martyna, Glenn J.; Tuckerman, Mark E.

    2003-02-01

    In this paper (Paper I) and a companion paper (Paper II), novel new algorithms and applications of the isokinetic ensemble as generated by Gauss' principle of least constraint, pioneered for use with molecular dynamics 20 years ago, are presented for biophysical, path integral, and Car-Parrinello based ab initio molecular dynamics. In Paper I, a new "extended system" version of the isokinetic equations of motion that overcomes the ergodicity problems inherent in the standard approach, is developed using a new theory of non-Hamiltonian phase space analysis [M. E. Tuckerman et al., Europhys. Lett. 45, 149 (1999); J. Chem. Phys. 115, 1678 (2001)]. Reversible multiple time step integrations schemes for the isokinetic methods, first presented by Zhang [J. Chem. Phys. 106, 6102 (1997)] are reviewed. Next, holonomic constraints are incorporated into the isokinetic methodology for use in fast efficient biomolecular simulation studies. Model and realistic examples are presented in order to evaluate, critically, the performance of the new isokinetic molecular dynamic schemes. Comparisons are made to the, now standard, canonical dynamics method, Nosé-Hoover chain dynamics [G. J. Martyna et al., J. Chem. Phys. 97, 2635 (1992)]. The new isokinetic techniques are found to yield more efficient sampling than the Nosé-Hoover chain method in both path integral molecular dynamics and biophysical molecular dynamics calculations. In Paper II, the use of isokinetic methods in Car-Parrinello based ab initio molecular dynamics calculations is presented.

  14. Isokinetic strength test and functional outcomes in proximal humeral fractures treated with a locking plate.

    PubMed

    Costantino, Cosimo; Verdano, Michele Arcangelo; Jacopetti, Marco; Romiti, Davide; Lunini, Enricomaria; Pellegrini, Andrea; Ceccarelli, Francesco

    2014-09-01

    Despite the use of many shoulder outcome scales in subjects with rotator cuff pathology or instability symptoms, it can be problematic to select an instrumental evaluation in the shoulder trauma population. In this study we evaluated patients with proximal humeral fractures treated with internal fixation with a locking plate, analyzing the recovery of strength with an isokinetic test and its correlation with clinical and functional outcomes. We enrolled 46 individuals (17 men, 29 women). The evaluation included a structured interview, measurement of ROM, isokinetic strength test and Constant-Murley and QuickDASH scores. The isokinetic test was performed in flexion/extension and external/internal rotation of the operated shoulder in comparison with the contralateral side and concentric contractions in all movements. The parameter tested was peak torque. In the operated shoulder values we noticed a statistically significant correlation between the QuickDASH and Constant-Murley score. QuickDASH showed a significant correlation with flexion isokinetic strength, partial correlation with extension isokinetic values and no correlation with external/internal rotation values. In addition, we found a correlation between the Constant-Murley score and all the isokinetic strength parameters. Comparing the operated shoulder and the contralateral, in Neer type 2 fractures there was no significant difference in all the isokinetic peak torque values; in Neer type 3 and type 4, there was a significant statistical difference in both flexion peak torque values and no significant difference in the other movements. The isokinetic test can give objective data on strength recovery and could help the surgeon's clinical evaluation to assess the functional recovery of the operated shoulder over time. We believe that the isokinetic test and Constant-Murley score could act as a reference in the evaluation of post-surgical outcome of proximal humeral fractures. Furthermore, the type of fracture

  15. Upper Quadrant Field Tests and Isokinetic Upper Limb Strength in Overhead Athletes.

    PubMed

    Borms, Dorien; Maenhout, Annelies; Cools, Ann M

    2016-10-01

    Isokinetic testing is used to determine possible deficits in upper extremity strength in overhead athletes. Given that isokinetic testing is restricted to a laboratory setting, field tests, such as the Seated Medicine Ball Throw (SMBT) and Upper Quarter Y-Balance Test (YBT-UQ), were developed to assess upper body performance. The relationships between these field tests and isokinetic strength have not been examined. To investigate the relationship between isokinetic strength testing for shoulder external and internal rotation and elbow flexion and extension and SMBT distance and YBT-UQ performance in overhead athletes. Cross-sectional study. Institutional laboratory. A total of 29 healthy overhead athletes (14 men, 15 women; age = 21.6 ± 2.5 years, height = 177.7 ± 9.7 cm, mass = 70.3 ± 11.5 kg). A Biodex dynamometer was used to measure the isokinetic strength of the shoulder and elbow muscles. Upper extremity performance was assessed using the SMBT and YBT-UQ. We used Pearson correlation coefficients and coefficients of determination to analyze the relationship between SMBT and YBT-UQ performance and the isokinetic strength variables. We observed moderate to strong correlations between the SMBT and isokinetic shoulder and elbow strength (r range = 0.595-0.855) but no correlations between the YBT-UQ and isokinetic strength variables. The shared variance between these strength variables and the SMBT ranged from 35.4% to 64.5% for shoulder strength and 58.5% to 73.1% for elbow strength. These findings suggested that the SMBT is a reliable, low-cost, and easy- and quick-to-administer alternative to isokinetic testing for evaluating upper extremity strength in a clinical setting. Performance on the YBT-UQ did not seem to be related to upper limb strength and, therefore, cannot be used for this purpose. Using the YBT-UQ for other purposes may have value.

  16. The critical power concept in all-out isokinetic exercise.

    PubMed

    Dekerle, Jeanne; Barstow, Thomas J; Regan, Luke; Carter, Helen

    2014-11-01

    The critical power concept has been applied to constant-load exhaustive exercise and recently validated for 3-min all-out exercise. To test the application of critical power to a 3-min all-out isokinetic cycling exercise. Single-group, experimental, comparative design. Nine participants performed a 3-min all-out isokinetic test and 4-5 constant-load exhaustive trials, at 60 and 100 rpm, on an electrically-braked cycle. The linear P-t-1 relationship was modelled using a 2-parameter model (slope: critical power; intercept: Anaerobic Work Capacity). End power and accumulated work done above EP were calculated from the 3-min tests. No significant difference and a significant correlation was found between end power and critical power (60 rpm: 259 ± 40 W vs. 245 ± 38 W, P > 0.05; r = 0.85, P<0.01; 100 rpm: 227 ± 57 W vs. 212 ± 44 W, P > 0.05; r = 0.86, P<0.01). The Bias ± 95% limits of agreement were 14 ± 42 W at 60 rpm and 15 ± 57 W at 100 rpm. Work done above EP (60 rpm: 14.7 ± 3.0 kJ; 100 rpm: 17.3 ± 3.1 kJ) was not significantly different to the anaerobic work capacity (60 rpm: 16.2 ± 3.2 kJ; 100 rpm: 20.6 ± 6.4 kJ; P>0.05) but with only a significant correlation at 60 rpm (r = -0.71, P<0.05). The 2-parameter model underpinning the critical power construct can be applied to a 3-min all-out isokinetic test. End power does not differ and correlates with critical power. However, a further insight into levels of agreement leads to some scepticism concerning the use of the two variables interchangeably. The great intra-subject differences between work done above EP and the intercept of the P-t-1 relationship should also be considered. Copyright © 2013. Published by Elsevier Ltd.

  17. Isokinetic Strength Profile of Elite Female Handball Players.

    PubMed

    Xaverova, Zuzana; Dirnberger, Johannes; Lehnert, Michal; Belka, Jan; Wagner, Herbert; Orechovska, Karolina

    2015-12-22

    Systematic assessment of muscle strength of the lower extremities throughout the annual training cycle in athletes is crucial from a performance perspective for the optimization of the training process, as well as a health perspective with regard to injury prevention. The main aim of the present study was to determine isokinetic muscle strength of the knee flexors and extensors in female handball players at the beginning of a preparatory period and to assess whether there were any differences between players of different performance levels. The performance level was expressed by means of membership of the Women's Junior National Handball Team (JNT, n=8) or the Women's National Handball Team (NT, n=9). The isokinetic peak torque during concentric and eccentric single-joint knee flexion and extension was measured at angular velocities of 60, 180, 240°/s (concentric) and 60°/s (eccentric). The Mann-Whitney test showed no significant differences in the peak torques or ipsilateral ratios between the two groups. The bilateral force deficit (BFD) for concentric extension at 240°/s was significantly higher in the JNT compared with the NT (p=0.04; d=1.02). However, the results of individual evaluation show that the BFD was more frequent in the NT in most measurements. A high BFD was evident in the eccentric mode in both groups highlighting a need for particular strengthening. With regard to low strength ratios a prevention programme should be suggested for both observed groups of professional female handball players to reduce the risk of injury.

  18. Isokinetic Strength Profile of Elite Female Handball Players

    PubMed Central

    Xaverova, Zuzana; Dirnberger, Johannes; Lehnert, Michal; Belka, Jan; Wagner, Herbert; Orechovska, Karolina

    2015-01-01

    Systematic assessment of muscle strength of the lower extremities throughout the annual training cycle in athletes is crucial from a performance perspective for the optimization of the training process, as well as a health perspective with regard to injury prevention. The main aim of the present study was to determine isokinetic muscle strength of the knee flexors and extensors in female handball players at the beginning of a preparatory period and to assess whether there were any differences between players of different performance levels. The performance level was expressed by means of membership of the Women’s Junior National Handball Team (JNT, n=8) or the Women’s National Handball Team (NT, n=9). The isokinetic peak torque during concentric and eccentric single-joint knee flexion and extension was measured at angular velocities of 60, 180, 240°/s (concentric) and 60°/s (eccentric). The Mann-Whitney test showed no significant differences in the peak torques or ipsilateral ratios between the two groups. The bilateral force deficit (BFD) for concentric extension at 240°/s was significantly higher in the JNT compared with the NT (p=0.04; d=1.02). However, the results of individual evaluation show that the BFD was more frequent in the NT in most measurements. A high BFD was evident in the eccentric mode in both groups highlighting a need for particular strengthening. With regard to low strength ratios a prevention programme should be suggested for both observed groups of professional female handball players to reduce the risk of injury. PMID:26839626

  19. Phase space structure and dynamics for the Hamiltonian isokinetic thermostat

    NASA Astrophysics Data System (ADS)

    Collins, Peter; Ezra, Gregory S.; Wiggins, Stephen

    2010-07-01

    We investigate the phase space structure and dynamics of a Hamiltonian isokinetic thermostat, for which ergodic thermostat trajectories at fixed (zero) energy generate a canonical distribution in configuration space. Model potentials studied consist of a single bistable mode plus transverse harmonic modes. Interpreting the bistable mode as a reaction (isomerization) coordinate, we establish connections with the theory of unimolecular reaction rates, in particular the formulation of isomerization rates in terms of gap times. In the context of molecular reaction rates, the distribution of gap times (or associated lifetimes) for a microcanonical ensemble initiated on the dividing surface is of great dynamical significance; an exponential lifetime distribution is usually taken to be an indicator of "statistical" behavior. Moreover, comparison of the magnitude of the phase space volume swept out by reactive trajectories as they pass through the reactant region with the total phase space volume (classical density of states) for the reactant region provides a necessary condition for ergodic dynamics. We compute gap times, associated lifetime distributions, mean gap times, reactive fluxes, reactive volumes, and total reactant phase space volumes for model thermostat systems with three and four degrees of freedom at three different temperatures. At all three temperatures, the necessary condition for ergodicity is approximately satisfied. At high temperatures a nonexponential lifetime distribution is found, while at low temperatures the lifetime is more nearly exponential. The degree of exponentiality of the lifetime distribution is quantified by computing the information entropy deficit with respect to pure exponential decay. The efficacy of the Hamiltonian isokinetic thermostat is examined by computing coordinate distributions averaged over single long trajectories initiated on the dividing surface.

  20. Body Composition and Anthropometric Correlates of Isokinetic Leg Extension Strength of Young Adult Males.

    ERIC Educational Resources Information Center

    Nutter, June; Thorland, William G.

    1987-01-01

    This study examined the relative importance of body size and composition as determinants of differences in isokinetic leg extensor strength in young adult males performing at slow, moderate, and fast speeds. Results are discussed. (Author/MT)

  1. Effects of isokinetic passive exercise and isometric muscle contraction on passive stiffness.

    PubMed

    Terada, Shigeru; Miaki, Hiroichi; Uchiyama, Keita; Hayakawa, Shozo; Yamazaki, Toshiaki

    2013-10-01

    [Purpose] The purpose of this study was to investigate the effects of isokinetic passive exercise and motion velocity on passive stiffness. In addition, we also discuss the effects of the contraction of agonist and antagonist muscles on passive stiffness. [Subjects] The subjects were 20 healthy men with no bone or joint disease. [Methods] Isokinetic passive exercise and isometric muscle contraction were performed on an isokinetic dynamometer. The angular acceleration measured by the accelerometer was compared before and after each task. [Results] After the passive exercise, the angular acceleration increased in the phase of small damped oscillation. Moreover, the effect was higher at high-speed movement. The angular acceleration was decreased by the contraction of the agonist muscle. Conversely, the angular acceleration was increased by the contraction of the antagonist muscle. [Conclusion] Isokinetic passive exercise reduced passive stiffness. Our results suggest the possibility that passive stiffness is increased by agonist muscle contraction and decreased by antagonist muscle contraction.

  2. Effect of cold water immersion on repeated 1-km cycling performance in the heat.

    PubMed

    Peiffer, Jeremiah J; Abbiss, Chris R; Watson, Greig; Nosaka, Kazunori; Laursen, Paul B

    2010-01-01

    This study examined the effect of a short cold water immersion (CWI) intervention on rectal and muscle temperature, isokinetic strength and 1-km cycling time trial performance in the heat. Ten male cyclists performed a 1-km time trial at 35.0+/-0.3 degrees C and 40.0+/-3.0% relative humidity, followed by 20 min recovery sitting in either cold water (14 degrees C) for 5 min or in 35 degrees C air (control); a second 1-km time trial immediately followed. Peak and mean cycling power output were recorded for both time trials. Rectal and muscle temperature, and maximal isokinetic concentric torque of the knee extensors were measured before and immediately after the first and second time trials. Rectal temperature was not different between cold water immersion and control conditions at any time points. After the second time trial, however, muscle temperature was significantly lower (-1.3+/-0.7 degrees C) in cold water immersion compared with the control trial. While peak and mean power decreased from the first to second time trial in both conditions (-86+/-54 W and -24+/-16 W, respectively), maximal isokinetic concentric torque was similar between conditions at all time points. The 5 min cold water immersion intervention lowered muscle temperature but did not affect isokinetic strength or 1-km cycling performance. Copyright (c) 2008 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  3. Isokinetic assessment of the effects of botulinum toxin injection on spasticity and voluntary strength in patients with spastic hemiparesis.

    PubMed

    Hameau, S; Bensmail, D; Robertson, J; Boudarham, J; Roche, N; Zory, R

    2014-10-01

    Peak knee flexion during swing phase is frequently reduced following stroke. The main treatment is botulinum toxin injection (BoNT-A) of the Rectus Femoris (RF) muscle. BoNT-A injections have been shown to decrease spasticity (assessed using the modified Ashworth scale) and to improve peak knee flexion during swing phase. Although the effect of BoNT-A has been clearly demonstrated on kinematic parameters during gait, the direct effects on spasticity and strength have been little studied using objective and sensitive outcome measures. The aim of this study was to use an isokinetic dynamometer to assess the effects of BoNT-A injection in the RF on stretch reflex-related torque at the knee joint and peak voluntary knee flexor and extensor torque and to evaluate the effect on functional capacity. Before-after trial: Assessments were carried out pre and post (four weeks) RF BoNT-A injection. Clinical and isokinetic evaluations were carried out. Ambulatory care in a hospital setting. Participants. Population-based sample of fourteen chronic spastic hemiparetic patients with stiff knee gait. Primary outcome measurements were stretch reflex-related torque at the knee joint and peak voluntary knee flexor and extensor torque. Secondary outcomes were knee angle at peak torque, the slope of the torque velocity curve, stiffness and functional outcomes. Peak knee extensor torque was significantly decreased and peak knee flexor torque was significantly increased during maximal voluntary concentric and isometric contractions following BoNT-A injection of the RF. Stretch reflex-related torque evaluated during passive stretching movements was reduced and the angle of occurrence of the peak was greater. Functional outcomes did not change. CONCLUSIONS AND CLINICAL REHABILITATION IMPACT: The results of this study indicate that BoNT-A injection reduced RF spasticity but also reduced quadriceps strength. In contrast, knee flexor strength increased. These changes did not, however, lead to

  4. Prediction of hamstring injury in professional soccer players by isokinetic measurements.

    PubMed

    Dauty, Marc; Menu, Pierre; Fouasson-Chailloux, Alban; Ferréol, Sophie; Dubois, Charles

    2016-01-01

    previous studies investigating the ability of isokinetic strength ratios to predict hamstring injuries in soccer players have reported conflicting results. to determine if isokinetic ratios are able to predict hamstring injury occurring during the season in professional soccer players. case-control study; 3. from 2001 to 2011, 350 isokinetic tests were performed in 136 professional soccer players at the beginning of the soccer season. Fifty-seven players suffered hamstring injury during the season that followed the isokinetic tests. These players were compared with the 79 uninjured players. The bilateral concentric ratio (hamstring-to-hamstring), ipsilateral concentric ratio (hamstring-to-quadriceps), and mixed ratio (eccentric/concentric hamstring-to-quadriceps) were studied. The predictive ability of each ratio was established based on the likelihood ratio and post-test probability. the mixed ratio (30 eccentric/240 concentric hamstring-to-quadriceps) <0.8, ipsilateral ratio (180 concentric hamstring-to-quadriceps) <0.47, and bilateral ratio (60 concentric hamstring-to-hamstring) <0.85 were the most predictive of hamstring injury. The ipsilateral ratio <0.47 allowed prediction of the severity of the hamstring injury, and was also influenced by the length of time since administration of the isokinetic tests. isokinetic ratios are useful for predicting the likelihood of hamstring injury in professional soccer players during the competitive season.

  5. The Application of Isokinetics in Testing and Rehabilitation of the Shoulder Complex

    PubMed Central

    Ellenbecker, Todd S.; Davies, George J.

    2000-01-01

    Objective: We review the application of isokinetic testing and training for the shoulder complex, the interpretation of isokinetic testing data, and the application of normative data in the rehabilitation and performance enhancement of the athlete. Data Sources: We searched MEDLINE for the years 1989- 1999 using the key words “isokinetics,” “shoulder,” and “upper extremity.” Data Synthesis: Isokinetic testing and training is an integral part of the comprehensive evaluation and treatment of the shoulder complex. This mode of exercise allows for objective, isolated joint testing and training. Conclusions/Recommendations: Isokinetic training and testing is an important part of the comprehensive evaluation and rehabilitation of the patient with a shoulder injury. Research has demonstrated its efficacy in training and in providing clinically relevant information regarding muscular performance. When integrated with a complete history, subjective examination, and physical and functional evaluation, isokinetic exercise can be a valuable tool for the clinician in the assessment, rehabilitation, and performance enhancement of the athlete. ImagesFigure 1. PMID:16558647

  6. Prediction of hamstring injury in professional soccer players by isokinetic measurements

    PubMed Central

    Dauty, Marc; Menu, Pierre; Fouasson-Chailloux, Alban; Ferréol, Sophie; Dubois, Charles

    2016-01-01

    Summary Objectives previous studies investigating the ability of isokinetic strength ratios to predict hamstring injuries in soccer players have reported conflicting results. Hypothesis to determine if isokinetic ratios are able to predict hamstring injury occurring during the season in professional soccer players. Study Design case-control study; Level of evidence: 3. Methods from 2001 to 2011, 350 isokinetic tests were performed in 136 professional soccer players at the beginning of the soccer season. Fifty-seven players suffered hamstring injury during the season that followed the isokinetic tests. These players were compared with the 79 uninjured players. The bilateral concentric ratio (hamstring-to-hamstring), ipsilateral concentric ratio (hamstring-to-quadriceps), and mixed ratio (eccentric/concentric hamstring-to-quadriceps) were studied. The predictive ability of each ratio was established based on the likelihood ratio and post-test probability. Results the mixed ratio (30 eccentric/240 concentric hamstring-to-quadriceps) <0.8, ipsilateral ratio (180 concentric hamstring-to-quadriceps) <0.47, and bilateral ratio (60 concentric hamstring-to-hamstring) <0.85 were the most predictive of hamstring injury. The ipsilateral ratio <0.47 allowed prediction of the severity of the hamstring injury, and was also influenced by the length of time since administration of the isokinetic tests. Conclusion isokinetic ratios are useful for predicting the likelihood of hamstring injury in professional soccer players during the competitive season. PMID:27331039

  7. Repeated nightmares

    MedlinePlus

    ... different from night terrors . Alternative Names Nightmares - repeated; Dream anxiety disorder References American Academy of Family Physicians. Information from your family doctor. Nightmares and night terrors in children. ...

  8. The acute effects of flotation restricted environmental stimulation technique on recovery from maximal eccentric exercise.

    PubMed

    Morgan, Paul M; Salacinski, Amanda J; Stults-Kolehmainen, Matthew A

    2013-12-01

    Flotation restricted environmental stimulation technique (REST) involves compromising senses of sound, sight, and touch by creating a quiet dark environment. The individual lies supine in a tank of Epsom salt and water heated to roughly skin temperature (34-35° C). This study was performed to determine if a 1-hour flotation REST session would aid in the recovery process after maximal eccentric knee extensions and flexions. Twenty-four untrained male students (23.29 ± 2.1 years, 184.17 ± 6.85 cm, 85.16 ± 11.54 kg) participated in a randomized, repeated measures crossover study. The participants completed 2 exercise and recovery protocols: a 1-hour flotation REST session and a 1-hour seated control (passive recovery). After isometric muscle strength testing, participants were fatigued with eccentric isokinetic muscle contractions (50 repetitions at 60°·s) of the nondominant knee extensors and flexors. Blood lactate, blood glucose, heart rate, OMNI-rating of perceived exertion for resistance exercise (OMNI-RPE), perceived pain, muscle soreness, and isometric strength were collected before exercise, after treatment, and 24 and 48 hours later. A multivariate analysis of covariance found that treatment had a significant main effect on blood lactate, whereas subsequent univariate analyses of variance found statistical significance with the immediate posttreatment blood lactate measures. The results indicate that flotation REST appears to have a significant impact on blood lactate and perceived pain compared with a 1-hour passive recovery session in untrained healthy men. No difference was found between conditions for muscle strength, blood glucose, muscle soreness, heart rate, or OMNI-RPE. Flotation REST may be used for recreational and professional athletes to help reduce blood lactate levels after eccentric exercise.

  9. Maximally nonlocal theories cannot be maximally random.

    PubMed

    de la Torre, Gonzalo; Hoban, Matty J; Dhara, Chirag; Prettico, Giuseppe; Acín, Antonio

    2015-04-24

    Correlations that violate a Bell inequality are said to be nonlocal; i.e., they do not admit a local and deterministic explanation. Great effort has been devoted to study how the amount of nonlocality (as measured by a Bell inequality violation) serves to quantify the amount of randomness present in observed correlations. In this work we reverse this research program and ask what do the randomness certification capabilities of a theory tell us about the nonlocality of that theory. We find that, contrary to initial intuition, maximal randomness certification cannot occur in maximally nonlocal theories. We go on and show that quantum theory, in contrast, permits certification of maximal randomness in all dichotomic scenarios. We hence pose the question of whether quantum theory is optimal for randomness; i.e., is it the most nonlocal theory that allows maximal randomness certification? We answer this question in the negative by identifying a larger-than-quantum set of correlations capable of this feat. Not only are these results relevant to understanding quantum mechanics' fundamental features, but also put fundamental restrictions on device-independent protocols based on the no-signaling principle.

  10. Shortening behavior of the different components of muscle-tendon unit during isokinetic plantar flexions.

    PubMed

    Hauraix, Hugo; Nordez, Antoine; Dorel, Sylvain

    2013-10-01

    The torque-velocity relationship has been widely considered as reflecting the mechanical properties of the contractile apparatus, and the influence of tendinous tissues on this relationship obtained during in vivo experiments remains to be determined. This study describes the pattern of shortening of various muscle-tendon unit elements of the triceps surae at different constant angular velocities and quantifies the contributions of fascicles, tendon, and aponeurosis to the global muscle-tendon unit shortening. Ten subjects performed isokinetic plantar flexions at different preset angular velocities (i.e., 30, 90, 150, 210, 270, and 330°/s). Ultrafast ultrasound measurements were performed on the muscle belly and on the myotendinous junction of the medial and lateral gastrocnemius muscles. The contributions of fascicles, tendon, and aponeurosis to global muscle-tendon unit shortening velocity were calculated for velocity conditions for four parts of the total range of motion. For both muscles, the fascicles' contribution decreased throughout the motion (73.5 ± 21.5% for 100-90° angular range to 33.7 ± 20.2% for 80-70°), whereas the tendon contribution increased (25.8 ± 15.4 to 55.6 ± 16.8%). In conclusion, the tendon contribution to the global muscle-tendon unit shortening is significant even during a concentric contraction. However, this contribution depends on the range of motion analyzed. The intersubject variability found in the maximal fascicle shortening velocity, for a given angular velocity, suggests that some subjects might possess a more efficient musculoarticular complex to produce the movement velocity. These findings are of great interest for understanding the ability of muscle-tendon shortening velocity.

  11. Unextendible maximally entangled bases

    SciTech Connect

    Bravyi, Sergei; Smolin, John A.

    2011-10-15

    We introduce the notion of the unextendible maximally entangled basis (UMEB), a set of orthonormal maximally entangled states in C{sup d} x C{sup d} consisting of fewer than d{sup 2} vectors which have no additional maximally entangled vectors orthogonal to all of them. We prove that UMEBs do not exist for d=2 and give explicit constructions for a six-member UMEB with d=3 and a 12-member UMEB with d=4.

  12. Total Water Content Measurements with an Isokinetic Sampling Probe

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.; Miller, Dean R.; Bidwell, Colin S.

    2010-01-01

    The NASA Glenn Research Center has developed a Total Water Content (TWC) Isokinetic Sampling Probe. Since it is not sensitive to cloud water particle phase nor size, it is particularly attractive to support super-cooled large droplet and high ice water content aircraft icing studies. The instrument is comprised of the Sampling Probe, Sample Flow Control, and Water Vapor Measurement subsystems. Analysis and testing have been conducted on the subsystems to ensure their proper function and accuracy. End-to-end bench testing has also been conducted to ensure the reliability of the entire instrument system. A Stokes Number based collection efficiency correction was developed to correct for probe thickness effects. The authors further discuss the need to ensure that no condensation occurs within the instrument plumbing. Instrument measurements compared to facility calibrations from testing in the NASA Glenn Icing Research Tunnel are presented and discussed. There appears to be liquid water content and droplet size effects in the differences between the two measurement techniques.

  13. The LISST-SL streamlined isokinetic suspended-sediment profiler

    USGS Publications Warehouse

    Gray, John R.; Agrawal, Yogesh C.; Pottsmith, H. Charles

    2004-01-01

    The new manually deployed Laser In Situ Scattering Transmissometer-StreamLined profiler (LISST-SL) represents a major technological advance for suspended-sediment measurements in rivers. The LISST-SL is being designed to provide real-time data on sediment concentrations and particle-size distributions. A pressure sensor and current meter provide real-time depth and ambient velocity data, respectively. The velocity data are also used to control pumpage across an internal laser so that the intake velocity is constantly adjusted to match the ambient stream velocity. Such isokinetic withdrawal is necessary for obtaining representative sedimentary measurements in streamflow, and ensures compliance with established practices. The velocity and sediment-concentration data are used to compute fluxes for up to 32 particle-size classes at points, verticals, or in the entire stream cross section. All data are stored internally, as well as transmitted via a 2-wire conductor to the operator using a specially developed communication protocol. The LISST-SL's performance will be measured and compared to published sedimentological accuracy criteria, and a performance summary will be placed on-line.

  14. Isokinetic TWC Evaporator Probe: Calculations and Systemic Uncertainty Analysis

    NASA Technical Reports Server (NTRS)

    Davison, Craig R.; Strapp, J. Walter; Lilie, Lyle; Ratvasky, Thomas P.; Dumont, Christopher

    2016-01-01

    A new Isokinetic Total Water Content Evaporator (IKP2) was downsized from a prototype instrument, specifically to make airborne measurements of hydrometeor total water content (TWC) in deep tropical convective clouds to assess the new ice crystal Appendix D icing envelope. The probe underwent numerous laboratory and wind tunnel investigations to ensure reliable operation under the difficult high altitude/speed/TWC conditions under which other TWC instruments have been known to either fail, or have unknown performance characteristics and the results are presented in a companion paper. This paper presents the equations used to determine the total water content (TWC) of the sampled atmosphere from the values measured by the IKP2 or necessary ancillary data from other instruments. The uncertainty in the final TWC is determined by propagating the uncertainty in the measured values through the calculations to the final result. Two techniques were used and the results compared. The first is a typical analytical method of propagating uncertainty and the second performs a Monte Carlo simulation. The results are very similar with differences that are insignificant for practical purposes. The uncertainty is between 2 percent and 3 percent at most practical operating conditions. The capture efficiency of the IKP2 was also examined based on a computational fluid dynamic simulation of the original IKP and scaled down to the IKP2. Particles above 24 microns were found to have a capture efficiency greater than 99 percent at all operating conditions.

  15. Isokinetic TWC Evaporator Probe: Calculations and Systemic Uncertainty Analysis

    NASA Technical Reports Server (NTRS)

    Davison, Craig R.; Strapp, John W.; Lilie, Lyle E.; Ratvasky, Thomas P.; Dumont, Christopher

    2016-01-01

    A new Isokinetic Total Water Content Evaporator (IKP2) was downsized from a prototype instrument, specifically to make airborne measurements of hydrometeor total water content (TWC) in deep tropical convective clouds to assess the new ice crystal Appendix D icing envelope. The probe underwent numerous laboratory and wind tunnel investigations to ensure reliable operation under the difficult high altitude/speed/TWC conditions under which other TWC instruments have been known to either fail, or have unknown performance characteristics and the results are presented in a companion paper (Ref. 1). This paper presents the equations used to determine the total water content (TWC) of the sampled atmosphere from the values measured by the IKP2 or necessary ancillary data from other instruments. The uncertainty in the final TWC is determined by propagating the uncertainty in the measured values through the calculations to the final result. Two techniques were used and the results compared. The first is a typical analytical method of propagating uncertainty and the second performs a Monte Carlo simulation. The results are very similar with differences that are insignificant for practical purposes. The uncertainty is between 2 and 3 percent at most practical operating conditions. The capture efficiency of the IKP2 was also examined based on a computational fluid dynamic simulation of the original IKP and scaled down to the IKP2. Particles above 24 micrometers were found to have a capture efficiency greater than 99 percent at all operating conditions.

  16. Isoconversional and Isokinetic Studies of 2605SA1 Metglass

    NASA Astrophysics Data System (ADS)

    Lilly Shanker Rao, T.; Shanker Rao, T.

    2015-02-01

    Isoconversional methods (KAS,OFW,Li-Tang,and Vyazovkin) as well as isokinetic methods ((IKP) and CR) are used to determine the activation energy for crystallization (E), pre-exponential factor (A) and the conversion function f(α), for Fe-based 2605SA1 metallic glass.The non-isothennal differential scanning calorimetry data obtained at different heating rates ranging from 2 to 10 K/min are utilized for the analysis. The E for the peak I and II obtained by the IKP method are in good agreement with the values obtained from various isoconversional methods. The calculated kinetic triplets from IKP for peak I is: E = 445.6 ± 24 kJ/mol, A = 9.4 × 1022 sec-1 and f(α) = [-ln(l-α)]1/4 and for peak II is : E=325.7 ± 8 kJ/mol, A= 7.1 × 1015 sec-1 and f(α) = α1/4. All the above mentioned methods are summarized and discussed elaborately from the point of view of their applicability and correctness.

  17. Isokinetic strength during knee flexion and extension in elite fencers.

    PubMed

    Poulis, I; Chatzis, S; Christopoulou, K; Tsolakis, Ch

    2009-06-01

    The relation of leg preference and muscular strength in elite fencers was examined. The dominant and nondominant extensor and flexor muscles of 30 elite fencers (M age = 18.2 yr., SD = 2.0 yr.; M height = 173 cm, SD=7.4 cm; M weight = 62.7 kg, SD=8.9 kg), who were members of the Greek national team, and 14 healthy, young, sedentary adults (8 men, 6 women; M age 23.4 yr., SD = 1.9; M height = 169 cm, SD = 10.5 cm; M weight = 66.3 kg, SD = 9.9) were tested for concentric isokinetic contraction at slow (30 to 60 degrees/sec.) and fast (240 degrees/sec.) angular velocities. Significant multivariate differences were found between groups for knee extension, angle of knee extension, knee flexion, and flexor/extensor peak torque ratio. In contrast, no significant difference was found between the dominant and nondominant legs. There was no significant difference in the flexor/extensor peak torque ratio among any of the concentric angular velocities tested. These findings suggest that long-term training in fencing influences the strength characteristics of the lower limbs.

  18. Cutoffs of isokinetic strength ratio and hamstring strain prediction in professional soccer players.

    PubMed

    Dauty, M; Menu, P; Fouasson-Chailloux, A

    2017-04-04

    Hamstring strain injuries frequently occur during professional soccer practice. Low hamstring strength represents an intrinsic modifiable risk factor but cutoffs of isokinetic knee strength ratios are controversial to predict hamstring strain in professional soccer players. We aimed to predict hamstring strain in accordance with cutoffs of isokinetic knee strength ratios. Bilateral, conventional, and functional isokinetic strength ratios were calculated in 194 professional soccer players at the beginning of 15 consecutive seasons. 36 soccer players presented a moderate hamstring strain and 158 were not injured. The different calculated isokinetic ratios were compared with the right and left limb of the uninjured population. Different usual cutoffs were tested: at 0.85 and 0.90 for the bilateral concentric and eccentric hamstring-to-hamstring ratio, at 0.60 and 0.47 for the conventional hamstring-to-quadriceps ratio and at 0.80 and 1 for the mixed hamstring-to-quadriceps ratio. The specific ratios for the studied population were also determined by the 10th percentile and then tested. Hamstring strain prediction was established in terms of odds ratios. No cutoff with bilateral, conventional, or functional isokinetic strength ratio was predictive of hamstring strain after univariate analysis. Specific cutoffs determined from the studied population were not more predictive. Very few injured soccer players presented values under the cutoffs at 0.47 for the conventional ratio and at 0.80 for the mixed ratio. Regardless of their values, cutoffs of isokinetic strength ratios were not predictive of hamstring injuries. The use of isokinetic cutoffs is not recommended to predict hamstring muscle strain in professional soccer players. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. [Comparison of the effectiveness of isokinetic vs isometric therapeutic exercise in patients with osteoarthritis of knee].

    PubMed

    Rosa, Uganet Hernández; Velásquez Tlapanco, Jorge; Lara Maya, Catalina; Villarreal Ríos, Enrique; Martínez González, Lidia; Vargas Daza, Emma Rosa; Galicia Rodríguez, Liliana

    2012-01-01

    Osteoarthritis is a chronic joint disease; isometric exercise leads to the development of mechanical work and isokinetic exercise leads to better joint mobility. To compare the effectiveness of isometric versus isokinetic therapeutic exercises in patients with knee osteoarthritis. Quasiexperimental study in a population of 45 to 75 year old patients with a diagnosis of knee osteoarthritis. Group 1 (experimental) was put under isokinetic exercises and group 2 (control) under isometric exercises. The sample size was of 33 patients per group; the allocation to the experimentation or control group was nonrandom, but stratified by degrees of knee osteoarthritis. The effectiveness of the exercise was measured in three dimensions: muscle strength, joint range and pain. The intervention lasted eight weeks and the physical activity was carried out every third day. The statistical analysis included averages, standard deviation, percentage, Chi square test, z test for two populations, t test for two independent populations and twin t test. The analysis of muscle strength comparing the categories independently demonstrates differences at 8 weeks; 33.3% of the isokinetic exercise is in the normal category and 15.2% in the isometric exercise (p= 0.04). There was not difference of joint range between groups, despite finding a stage I range in 100.0% of the isokinetic group and 97.0% in the isometric (p> 0.05) group. Pain was milder in the isokinetic exercise group at 8 weeks (p= 0.01) Isokinetic exercises have a greater effectiveness than isometric exercises for muscle strength and pain in patients with knee osteoarthritis. However, other studies with randomized designs are needed. Copyright © 2011 Elsevier España, S.L. All rights reserved.

  20. At return to play following hamstring injury the majority of professional football players have residual isokinetic deficits.

    PubMed

    Tol, Johannes L; Hamilton, Bruce; Eirale, Cristiano; Muxart, Patrice; Jacobsen, Philipp; Whiteley, Rod

    2014-09-01

    There is an ongoing debate regarding the optimal criteria for return to sport after an acute hamstring injury. Less than 10% isokinetic strength deficit is generally recommended but this has never been documented in professional football players after rehabilitation. Our aim was to evaluate isokinetic measurements in MRI-positive hamstring injuries. Isokinetic measurements of professional football players were obtained after completing a standardised rehabilitation programme. An isokinetic strength deficit of more than 10% compared with the contralateral site was considered abnormal. Reinjuries within 2 months were recorded. 52 players had a complete set of isokinetic testing before clinical discharge. There were 27 (52%) grade 1 and 25 (48%) grade 2 injuries. 35 of 52 players (67%) had at least one of the three hamstring-related isokinetic parameters that display a deficit of more than 10%. The percentage of players with 10% deficit for hamstring concentric 60°/s, 300°/s and hamstring eccentric was respectively 39%, 29% and 28%. There was no significant difference of mean isokinetic peak torques and 10% isokinetic deficits in players without reinjury (N=46) compared with players with reinjury (N=6). When compared with the uninjured leg, 67% of the clinically recovered hamstring injuries showed at least one hamstring isokinetic testing deficit of more than 10%. Normalisation of isokinetic strength seems not to be a necessary result of the successful completion of a football-specific rehabilitation programme. The possible association between isokinetic strength deficit and increased reinjury risk remains unknown. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  1. At return to play following hamstring injury the majority of professional football players have residual isokinetic deficits

    PubMed Central

    Tol, Johannes L; Hamilton, Bruce; Eirale, Cristiano; Muxart, Patrice; Jacobsen, Philipp; Whiteley, Rod

    2014-01-01

    Background There is an ongoing debate regarding the optimal criteria for return to sport after an acute hamstring injury. Less than 10% isokinetic strength deficit is generally recommended but this has never been documented in professional football players after rehabilitation. Our aim was to evaluate isokinetic measurements in MRI-positive hamstring injuries. Methods Isokinetic measurements of professional football players were obtained after completing a standardised rehabilitation programme. An isokinetic strength deficit of more than 10% compared with the contralateral site was considered abnormal. Reinjuries within 2 months were recorded. Results 52 players had a complete set of isokinetic testing before clinical discharge. There were 27 (52%) grade 1 and 25 (48%) grade 2 injuries. 35 of 52 players (67%) had at least one of the three hamstring-related isokinetic parameters that display a deficit of more than 10%. The percentage of players with 10% deficit for hamstring concentric 60°/s, 300°/s and hamstring eccentric was respectively 39%, 29% and 28%. There was no significant difference of mean isokinetic peak torques and 10% isokinetic deficits in players without reinjury (N=46) compared with players with reinjury (N=6). Conclusions When compared with the uninjured leg, 67% of the clinically recovered hamstring injuries showed at least one hamstring isokinetic testing deficit of more than 10%. Normalisation of isokinetic strength seems not to be a necessary result of the successful completion of a football-specific rehabilitation programme. The possible association between isokinetic strength deficit and increased reinjury risk remains unknown. PMID:24493666

  2. Effect of enzyme replacement therapy on isokinetic strength for all major muscle groups in four patients with Pompe disease-a long-term follow-up.

    PubMed

    Andreassen, Christer Swan; Schlütter, Jacob Mørup; Vissing, John; Andersen, Henning

    2014-05-01

    Pompe disease is a rare, inherited metabolic myopathy characterized by progressive weakness of the proximal limb and respiratory muscles. We report the findings from four patients with late-onset Pompe disease treated with α-glucosidase (Myozyme) for 2 (n=2) and 6 (n=2) years, and monitored with isokinetic dynamometry, 6-minute walking test (6MWT), and vital capacity. Patients were evaluated after 6, 12, 24, 36, 48, 60, and 72months. In two patients, muscle size estimated by MRI and DXA scanning was also performed prior to and following 6months of treatment. After 2years of α-glucosidase treatment, maximal isokinetic muscle strength increased by 11% (0%-50%) [median (range)] and 6MWT improved by 18% (2%-40%). In the two patients treated for 6years, the increase in muscle strength stabilized at 40% and 6MWT stabilized at 32%. The improvements primarily occurred during the first 6months of treatment. Interestingly, the weakest muscle groups seemed to benefit more than those less affected, and greater improvements occurred for flexor muscles compared to extensor muscles. Vital capacity did not improve on treatment.

  3. Comparison of nutritional intake, body composition, bone mineral density, and isokinetic strength in collegiate female dancers.

    PubMed

    Lim, Se-Na; Chai, Joo-Hee; Song, Jong Kook; Seo, Myong-Won; Kim, Hyun-Bae

    2015-12-01

    This study compared nutritional intake, body composition, bone mineral density, and isokinetic strength by dance type in collegiate female dancers. The study subjects included Korean dancers (n=12), ballet dancers (n=13), contemporary dancers (n=8), and controls (n=12). Nutritional intake was estimated using the Computer Aided Nutritional Analysis Program. Body composition and bone mineral density were measured using dual-energy X-ray absorptiometry. Isokinetic knee joint strength was measured by Cybex 770-NORM. All statistical analyses were performed by SAS 9.2. Means and standard deviations were calculated using descriptive statistics. One-way analysis of variance was applied to evaluate nutritional intake, body composition, bone mineral density, and isokinetic strength differences. Duncan multiple range test was used for post hoc testing. A level of significance was set at P<0.05. The study results indicated no significant differences in nutritional in-take among dancer types. Despite no significant differences in body composition among dancer types, contemporary and ballet dancers had lower body fat percentages than controls (P<0.05). No significant differences were seen in bone mineral density and bone mineral contents among dancer types. No significant differences were found in isokinetic strength in right or left knee flexion and extension at 60°/sec (P<0.05). There were significant differences in body composition and isokinetic strength between dancer groups and the control group. Further studies of different professional dance type and more scientific methods of dance training are needed.

  4. Effect of isokinetic training on quadriceps peak torgue in healthy subjects and patients with burn injury.

    PubMed

    Ahmed, Emad Tawfik; Abdel-aziem, Amr Almaz; Ebid, Anwar Abdelgayed

    2011-10-01

    To evaluate the improvement rate of quadriceps muscle peak torque in healthy subjects and patients with burn injuries after an isokinetic training programme. Thirty male volunteers, 15 healthy and 15 subjects with burn injury after complete healing, participated in the study. Concentric and eccentric torque of quadriceps was measured for both groups using an isokinetic dynamometer before and after 6 weeks of isokinetic training. The tests were performed at angular velocities of 30°/s and 90°/s. There was a significant increase in the quadricep speak torque for both groups at both angular velocities after isokinetic training. During eccentric contraction at angular velocities of 30°/s and 90°/s the percentage improvement in the burned group was higher than in the healthy group(p = 0.003 and p = 0.0008, respectively). During concentric contraction at an angular velocity of 30°/s the percentage improvement in the burned group was higher than the healthy group (p = 0.020). However, during concentric contraction at an angular velocity of 90°/s there was no significant difference between the groups (p = 0.742). The isokinetic training programme was effective in increasing the concentric and eccentric peak torque of the quadriceps muscle for healthy subjects and patients with burn injuries.

  5. The comparison of intraocular pressure reductions after isometric and isokinetic exercises in normal individuals.

    PubMed

    Avunduk, A M; Yilmaz, B; Sahin, N; Kapicioglu, Z; Dayanir, V

    1999-01-01

    The lowering effect of physical exercise on intraocular pressure (IOP) has been reported both in healthy people and those with glaucoma, but a comparison of the lowering effect of isometric and isokinetic exercises on IOP has not been conducted in any study. Our aims were to investigate the relationship between intensity of exercise and IOP, and whether a significant difference in IOP lowering effect existed between isometric and isokinetic exercises. Sixty-seven patients with an age range of 23-40 who had no ocular disease were randomly divided into two groups. While 31 patients in the first group, group A, performed isokinetic exercise with the Cybex 6000 dynamometer, 32 patients in the second group, group B, had isometric exercises with the same machine. IOP was measured in the right eye of patients with Shiotz tonometer just before and 10 min following exercise. Exercise intensity and total energy consumption were determined by the machine for each patient. While IOP values measured before exercise, the degree of exercise applied, and total energy consumption did not differ significantly between groups, both isometric and isotonic exercises lowered IOP significantly. As a result, isometric and isokinetic exercises lowered IOP in ophthalmologically normal subjects with direct relationship to exercise intensity and total energy consumption. Since the pressure lowering effect of isokinetic exercise was more significant, it might prove useful to glaucomatous patients.

  6. Isokinetic assessment of the hip muscles in patients with osteoarthritis of the knee

    PubMed Central

    Costa, Renata Alqualo; de Oliveira, Leda Magalhaes; Watanabe, Sandra Hiroko; Jones, Anamaria; Natour, Jamil

    2010-01-01

    OBJECTIVES: To evaluate the difference in isokinetic strength of hip muscles between patients with knee osteoarthritis (OA) and matched healthy controls, and to establish the correlation between this isokinetic strength and pain and function in patients with knee OA. METHODS: 25 patients with a diagnosis of unilateral knee OA, 25 patients with bilateral knee OA, and 50 matched controls were evaluated using the visual analog scale for pain, knee Lequesne index, Western Ontario and McMaster Universities questionnaire and an isokinetic test. RESULTS: The groups were matched for age, gender and body mass index. The results of the isokinetic test revealed lower peak torque of the hip in patients with OA of the knee than in the control group for all movements studied. Strong correlations were found between the peak torque, visual analog scale and function. CONCLUSIONS: Patients with OA of the knee exhibit lower isokinetic strength in the hip muscles than healthy control subjects. Strengthening the muscles surrounding the hip joint may help to decrease pain in people with knee OA. Some correlations between pain/function and peak torque were found. PMID:21340212

  7. Age specific isokinetic glenohumeral internal and external rotation strength in elite junior tennis players.

    PubMed

    Ellenbecker, T; Roetert, E P

    2003-03-01

    The high incidence of overuse shoulder injuries in elite junior tennis players is often attributed to both the high repetitive stresses inherent in the game, as well as muscular imbalances in the humeral rotators. The purpose of this study was to isokinetically measure concentric glenohumeral joint internal and external rotation strength, to develop a bilateral descriptive profile in elite junior tennis players across two age ranges. One hundred forty seven elite junior players between the ages of 12 and 21 were bilaterally tested on a Cybex isokinetic dynamometer with 90 degrees of abduction. Players were analysed in two groups (12-17 and 18-21 years of age), using isokinetic variables of peak torque and work relative to body weight. Data analysis consisted of ANOVAs, with dependent t-tests used for post-hoc testing where main effect differences were identified. Results indicated no significant main effect difference in the isokinetic relative parameters between the two age groups (p > .01). Significantly greater (p < .001) dominant arm internal rotation was measured in both groups for both males and females, with no significant difference in external rotation strength measured between extremities in either age group. These data show specific adaptations in shoulder strength and identify a relative muscular imbalance between the internal and external rotators on the dominant arm of elite junior tennis players. Normative data presented in this study can assist clinicians and researchers in interpreting isokinetic test results in elite junior tennis players.

  8. Short-term isokinetic training versus isotonic training: effects on asymmetry in strength of thigh muscles.

    PubMed

    Golik-Peric, Dragana; Drapsin, Miodrag; Obradovic, Borislav; Drid, Patrik

    2011-12-01

    The aim of this study was to investigate the effects of two training protocols on the isokinetic performance of athletes. The study was conducted in 38 athletes, (age 23.3 ± 3.6 years) participating in national level leagues of different sports, whose initial concentric hamstrings-to-quadriceps (conH/Q) torque ratio was lower than 0.5. During seasonal testing, an isokinetic measurement of knee extensors and flexors was performed at 60°/s. The athletes were divided into two groups. Nineteen athletes performed the isokinetic training protocol (IT) while the second group of 19 athletes followed the isotonic training protocol (RT). Both protocols lasted 4 weeks. After completing the training protocols, both groups underwent a final isokinetic testing. The isokinetic data revealed significant increases after training in measures of peak torque in both extensor and flexor muscle groups, in both the IT and RT study groups (p < 0.05). There were significant increases (p< 0.05) in conH/Q ratio in both groups after the implemented protocols, but greater in IT group. Consequently, applied IT protocol induced changes in working muscles, thereby restoring detected asymmetry to an acceptable balance more efficiently compared to RT protocol.

  9. Muscular performance characterization in athletes: a new perspective on isokinetic variables

    PubMed Central

    Amaral, Giovanna M.; Marinho, Hellen V. R.; Ocarino, Juliana M.; Silva, Paula L. P.; de Souza, Thales R.; Fonseca, Sérgio T.

    2014-01-01

    Background: Isokinetic dynamometry allows the measurement of several variables related to muscular performance, many of which are seldom used, while others are redundantly applied to the characterization of muscle function. Objectives: The present study aimed to establish the particular features of muscle function that are captured by the variables currently included in isokinetic assessment and to determine which variables best represent these features in order to achieve a more objective interpretation of muscular performance. Method: This study included 235 male athletes. They performed isokinetic tests of concentric knee flexion and extension of the dominant leg at a velocity of 60º/s. An exploratory factor analysis was performed. Results: The findings demonstrated that isokinetic variables can characterize more than muscle torque production and pointed to the presence of 5 factors that enabled the characterization of muscular performance according to 5 different domains or constructs. Conclusions: The constructs can be described by torque generation capacity; variation of the torque generation capacity along repetitions; movement deceleration capacity; mechanical/physiological factors of torque generation; and acceleration capacity (torque development). Fewer than eight out of sixteen variables are enough to characterize these five constructs. Our results suggest that these variables and these 5 domains may lead to a more systematic and optimized interpretation of isokinetic assessments. PMID:25590444

  10. Muscular performance characterization in athletes: a new perspective on isokinetic variables.

    PubMed

    Amaral, Giovanna M; Marinho, Hellen V R; Ocarino, Juliana M; Silva, Paula L P; Souza, Thales R de; Fonseca, Sérgio T

    2014-10-10

    Background: Isokinetic dynamometry allows the measurement of several variables related to muscular performance, many of which are seldom used, while others are redundantly applied to the characterization of muscle function. Objectives: The present study aimed to establish the particular features of muscle function that are captured by the variables currently included in isokinetic assessment and to determine which variables best represent these features in order to achieve a more objective interpretation of muscular performance. Method: This study included 235 male athletes. They performed isokinetic tests of concentric knee flexion and extension of the dominant leg at a velocity of 60º/s. An exploratory factor analysis was performed. Results: The findings demonstrated that isokinetic variables can characterize more than muscle torque production and pointed to the presence of 5 factors that enabled the characterization of muscular performance according to 5 different domains or constructs. Conclusions: The constructs can be described by torque generation capacity; variation of the torque generation capacity along repetitions; movement deceleration capacity; mechanical/physiological factors of torque generation; and acceleration capacity (torque development). Fewer than eight out of sixteen variables are enough to characterize these five constructs. Our results suggest that these variables and these 5 domains may lead to a more systematic and optimized interpretation of isokinetic assessments.

  11. Muscular performance characterization in athletes: a new perspective on isokinetic variables.

    PubMed

    Amaral, Giovanna M; Marinho, Hellen V R; Ocarino, Juliana M; Silva, Paula L P; de Souza, Thales R; Fonseca, Sérgio T

    2014-01-01

    Isokinetic dynamometry allows the measurement of several variables related to muscular performance, many of which are seldom used, while others are redundantly applied to the characterization of muscle function. The present study aimed to establish the particular features of muscle function that are captured by the variables currently included in isokinetic assessment and to determine which variables best represent these features in order to achieve a more objective interpretation of muscular performance. This study included 235 male athletes. They performed isokinetic tests of concentric knee flexion and extension of the dominant leg at a velocity of 60º/s. An exploratory factor analysis was performed. The findings demonstrated that isokinetic variables can characterize more than muscle torque production and pointed to the presence of 5 factors that enabled the characterization of muscular performance according to 5 different domains or constructs. The constructs can be described by torque generation capacity; variation of the torque generation capacity along repetitions; movement deceleration capacity; mechanical/physiological factors of torque generation; and acceleration capacity (torque development). Fewer than eight out of sixteen variables are enough to characterize these five constructs. Our results suggest that these variables and these 5 domains may lead to a more systematic and optimized interpretation of isokinetic assessments.

  12. Isokinetic Evaluation of Knee Extensor/Flexor Muscle Strength in Behcet's Patients.

    PubMed

    Durmus, Bekir; Emre, Sinan; Sahin, Nilay; Karincaoglu, Yelda; Dogan, Erdal; Baysal, Ozlem; Ersoy, Yuksel; Altay, Zuhal

    2014-08-24

    Background: Behçet's disease (BD) is an idiopathic, multisystemic, progressive disease. The purpose of this study is to compare the knee flexor and extensor isokinetic muscle strengths of Behcet's patients with that of healthy subjects. Methods: Twenty-five (13 male and 12 female) patients with BD and 25 (15 male and 10 female) healthy individuals were included in the study. Velocities of 90°/sec, 120°/sec, and 150°/sec were used for the isokinetic muscle strength testing. Patients with active inflammatory knee arthritis were excluded. Peak torque (Nm) and peak torque adjusted to body weight (%) were taken into consideration for comparison between study groups. Results: Compared to healthy controls, there was a statistically significant decrease in both the bilateral knee extensor and flexor muscle isokinetic peak torques(Nm) as well as the peak torques adjusted to body weight (%) at velocities of 90°/sec, 120°/sec and 150°/sec in patients with BD (p < 0.05). However, there was no significant difference in the agonist-antagonist ratio of the isokinetic peak torques of knee muscles between the two groups. Conclusion: In light of these findings, we have concluded that both knee flexor and extensor isokinetic muscle strengths are lower in BD. We therefore recommend careful monitoring of patients with BD in terms of muscle strength.

  13. Isokinetic Evaluation of Knee Extensor/Flexor Muscle Strength in Behcet's Patients.

    PubMed

    Durmus, B; Emre, S; Sahin, N; Karincaoglu, Y; Dogan, E; Baysal, O; Ersoy, Y; Altay, Z

    2015-01-01

    Behçet's disease (BD) is an idiopathic, multisystemic, progressive disease. The purpose of this study is to compare the knee flexor and extensor isokinetic muscle strengths of Behcet's patients with that of healthy subjects. Twenty-five (13 male and 12 female) patients with BD and 25 (15 male and 10 female) healthy individuals were included in the study. Velocities of 90°/sec, 120°/sec, and 150°/sec were used for the isokinetic muscle strength testing. Patients with active inflammatory knee arthritis were excluded. Peak torque (Nm) and peak torque adjusted to body weight (%) were taken into consideration for comparison between study groups. Compared to healthy controls, there was a statistically significant decrease in both the bilateral knee extensor and flexor muscle isokinetic peak torques(Nm) as well as the peak torques adjusted to body weight (%) at velocities of 90°/sec, 120°/sec and 150°/sec in patients with BD (p < 0.05). However, there was no significant difference in the agonist-antagonist ratio of the isokinetic peak torques of knee muscles between the two groups. In light of these findings, we have concluded that both knee flexor and extensor isokinetic muscle strengths are lower in BD. We therefore recommend careful monitoring of patients with BD in terms of muscle strength.

  14. Effects of different stretching techniques on the outcomes of isokinetic exercise in patients with knee osteoarthritis.

    PubMed

    Weng, Ming-Cheng; Lee, Chia-Ling; Chen, Chia-Hsin; Hsu, Jui-Jen; Lee, Wei-Der; Huang, Mao-Hsiung; Chen, Tien-Wen

    2009-06-01

    We recruited 132 subjects with bilateral knee osteoarthritis (Altman Grade II) to compare the effects of different stretching techniques on the outcomes of isokinetic muscle strengthening exercises. Patients were randomly divided into four groups (I-IV). The patients in Group I received isokinetic muscular strengthening exercises, Group II received bilateral knee static stretching and isokinetic exercises, Group III received proprioceptive neuromuscular facilitation (PNF) stretching and isokinetic exercises, and Group IV acted as controls. Outcomes were measured by changes in Lequesne's index, range of knee motion, visual analog pain scale, and peak muscle torques during knee flexion and extension. Patients in all the treated groups experienced significant reductions in knee pain and disability, and increased peak muscle torques after treatment and at follow-up. However, only patients in Groups II and III had significant improvements in range of motion and muscle strength gain during 60 degrees/second angular velocity peak torques. Group III demonstrated the greatest increase in muscle strength gain during 180 degrees/second angular velocity peak torques. In conclusion, stretching therapy could increase the effectiveness of isokinetic exercise in terms of functional improvement in patients with knee osteoarthritis. PNF techniques were more effective than static stretching.

  15. Comparison of nutritional intake, body composition, bone mineral density, and isokinetic strength in collegiate female dancers

    PubMed Central

    Lim, Se-Na; Chai, Joo-Hee; Song, Jong Kook; Seo, Myong-Won; Kim, Hyun-Bae

    2015-01-01

    This study compared nutritional intake, body composition, bone mineral density, and isokinetic strength by dance type in collegiate female dancers. The study subjects included Korean dancers (n=12), ballet dancers (n=13), contemporary dancers (n=8), and controls (n=12). Nutritional intake was estimated using the Computer Aided Nutritional Analysis Program. Body composition and bone mineral density were measured using dual-energy X-ray absorptiometry. Isokinetic knee joint strength was measured by Cybex 770-NORM. All statistical analyses were performed by SAS 9.2. Means and standard deviations were calculated using descriptive statistics. One-way analysis of variance was applied to evaluate nutritional intake, body composition, bone mineral density, and isokinetic strength differences. Duncan multiple range test was used for post hoc testing. A level of significance was set at P<0.05. The study results indicated no significant differences in nutritional in-take among dancer types. Despite no significant differences in body composition among dancer types, contemporary and ballet dancers had lower body fat percentages than controls (P<0.05). No significant differences were seen in bone mineral density and bone mineral contents among dancer types. No significant differences were found in isokinetic strength in right or left knee flexion and extension at 60°/sec (P<0.05). There were significant differences in body composition and isokinetic strength between dancer groups and the control group. Further studies of different professional dance type and more scientific methods of dance training are needed. PMID:26730387

  16. Quadriceps Strength in Patients With Isolated Cartilage Defects of the Knee: Results of Isokinetic Strength Measurements and Their Correlation With Clinical and Functional Results.

    PubMed

    Hirschmüller, Anja; Andres, Tasja; Schoch, Wolfgang; Baur, Heiner; Konstantinidis, Lukas; Südkamp, Norbert P; Niemeyer, Philipp

    2017-05-01

    Recent studies have found a significant deficit of maximum quadriceps strength after autologous chondrocyte implantation (ACI) of the knee. However, it is unclear whether muscular strength deficits in patients with cartilage damage exist prior to operative treatment. To isokinetically test maximum quadriceps muscle strength and quantify the impact of possible strength deficits on functional and clinical test results. Cross-sectional study; Level of evidence, 3. To identify clinically relevant muscular strength deficits, 24 patients (5 females, 19 males; mean age, 34.5 years; body mass index, 25.9 kg/m(2)) with isolated cartilage defects (mean onset, 5.05 years; SD, 7.8 years) in the knee joint underwent isokinetic strength measurements. Maximal quadriceps strength was recorded in 3 different testing modes: pure concentric contraction (flexors and extensors alternating work; con1), concentric-eccentric (only the extensors work concentrically and eccentrically; con2), and eccentric contraction in the alternating mode (ecc). Results were compared for functional performance (single-leg hop test), pain scales (visual analog scale [VAS], numeric rating scale [NRS]), self-reported questionnaires (International Knee Documentation Committee [IKDC], Knee Injury and Osteoarthritis Outcome Scale [KOOS]), and defect size (cm(2)). Compared with the uninjured leg, significantly lower quadriceps strength was detected in the injured leg in all isokinetic working modes (con1 difference, 27.76 N·m [SD 17.47; P = .003]; con2 difference, 21.45 N·m [SD, 18.45; P =.025]; ecc difference, 29.48 N·m [SD, 21.51; P = .001]), with the largest deficits found for eccentric muscle performance. Moderate negative correlations were observed for the subjective pain scales NRS and VAS. The results of the IKDC and KOOS questionnaires showed low, nonsignificant correlations with findings in the isokinetic measurement. Moreover, defect sizes (mean, 3.13 cm(2)) were of no importance regarding the

  17. Quadriceps Strength in Patients With Isolated Cartilage Defects of the Knee: Results of Isokinetic Strength Measurements and Their Correlation With Clinical and Functional Results

    PubMed Central

    Hirschmüller, Anja; Andres, Tasja; Schoch, Wolfgang; Baur, Heiner; Konstantinidis, Lukas; Südkamp, Norbert P.; Niemeyer, Philipp

    2017-01-01

    Background: Recent studies have found a significant deficit of maximum quadriceps strength after autologous chondrocyte implantation (ACI) of the knee. However, it is unclear whether muscular strength deficits in patients with cartilage damage exist prior to operative treatment. Purpose: To isokinetically test maximum quadriceps muscle strength and quantify the impact of possible strength deficits on functional and clinical test results. Study Design: Cross-sectional study; Level of evidence, 3. Methods: To identify clinically relevant muscular strength deficits, 24 patients (5 females, 19 males; mean age, 34.5 years; body mass index, 25.9 kg/m2) with isolated cartilage defects (mean onset, 5.05 years; SD, 7.8 years) in the knee joint underwent isokinetic strength measurements. Maximal quadriceps strength was recorded in 3 different testing modes: pure concentric contraction (flexors and extensors alternating work; con1), concentric-eccentric (only the extensors work concentrically and eccentrically; con2), and eccentric contraction in the alternating mode (ecc). Results were compared for functional performance (single-leg hop test), pain scales (visual analog scale [VAS], numeric rating scale [NRS]), self-reported questionnaires (International Knee Documentation Committee [IKDC], Knee Injury and Osteoarthritis Outcome Scale [KOOS]), and defect size (cm2). Results: Compared with the uninjured leg, significantly lower quadriceps strength was detected in the injured leg in all isokinetic working modes (con1 difference, 27.76 N·m [SD 17.47; P = .003]; con2 difference, 21.45 N·m [SD, 18.45; P =.025]; ecc difference, 29.48 N·m [SD, 21.51; P = .001]), with the largest deficits found for eccentric muscle performance. Moderate negative correlations were observed for the subjective pain scales NRS and VAS. The results of the IKDC and KOOS questionnaires showed low, nonsignificant correlations with findings in the isokinetic measurement. Moreover, defect sizes (mean, 3

  18. Neuromuscular adaptations to isoload versus isokinetic eccentric resistance training.

    PubMed

    Guilhem, Gaël; Cornu, Christophe; Maffiuletti, Nicola A; Guével, Arnaud

    2013-02-01

    The purpose of this study was to compare neuromuscular adaptations induced by work-matched isoload (IL) versus isokinetic (IK) eccentric resistance training. A total of 31 healthy subjects completed a 9-wk IL (n = 11) or IK (n = 10) training program for the knee extensors or did not train (control group; n = 10). The IL and IK programs consisted of 20 training sessions, which entailed three to five sets of eight repetitions in the respective modalities. The amount of work and the mean angular velocity were strictly matched between IL and IK conditions. Neuromuscular tests were performed before and after training and consisted of the assessment of quadriceps muscle strength, muscle architecture (vastus lateralis), EMG activity, and antagonist coactivation. IL, but not IK, eccentric resistance training enhanced eccentric strength at short muscle length (+20%), high-velocity eccentric strength (+15%), muscle thickness (+10%), and fascicle angle measured at rest (+11%; P < 0.05). Agonist EMG activity increased almost similarly for the two modalities, whereas antagonist coactivation was unaffected by training. IL proved to be more effective than IK training for improving quadriceps muscle strength and structure. It is conjectured that the rapid acceleration of the load in the early phase of IL eccentric movements (i.e., at short muscle lengths), which results in greater torque and angular velocities compared with IK actions, is the main determinant of strength and neuromuscular adaptations to eccentric training. These findings have important consequences for the optimization of IL and IK eccentric exercise for resistance training and rehabilitation purposes.

  19. Comparison of Recovery Strategies on Maximal Force-Generating Capacity and Electromyographic Activity Level of the Knee Extensor Muscles

    PubMed Central

    Zarrouk, Nidhal; Rebai, Haithem; Yahia, Abdelmoneem; Souissi, Nizar; Hug, François; Dogui, Mohamed

    2011-01-01

    Context: With regard to intermittent training exercise, the effects of the mode of recovery on subsequent performance are equivocal. Objective: To compare the effects of 3 types of recovery intervention on peak torque (PT) and electromyographic (EMG) activity of the knee extensor muscles after fatiguing isokinetic intermittent concentric exercise. Design: Crossover study. Setting: Research laboratory. Patients or Other Participants: Eight elite judo players (age = 18.4 ± 1.4 years, height = 180 ± 3 cm, mass = 77.0 ± 4.2 kg). Interventions : Participants completed 3 randomized sessions within 7 days. Each session consisted of 5 sets of 10 concentric knee extensions at 80% PT at 120°/s, with 3 minutes of recovery between sets. Recovery interventions were passive, active, and electromyostimulation. The PT and maximal EMG activity were recorded simultaneously while participants performed isokinetic dynamometer trials before and 3 minutes after the resistance exercise. Main Outcome Measure(s): The PT and maximal EMG activity from the knee extensors were quantified at isokinetic velocities of 60°/s, 120°/s, and 180°/s, with 5 repetitions at each velocity. Results: The reduction in PT observed after electromyo-stimulation was less than that seen after passive (P < .001) or active recovery (P < .001). The reduction in PT was less after passive recovery than after active recovery (P < .001). The maximal EMG activity level observed after electromyostimulation was higher than that seen after active recovery (P < .05). Conclusions: Electromyostimulation was an effective recovery tool in decreasing neuromuscular fatigue after high-intensity, intermittent isokinetic concentric exercise for the knee extensor muscles. Also, active recovery induced the greatest amount of neuromuscular fatigue. PMID:21944070

  20. Study on the control of variable resistance for isokinetic muscle training system.

    PubMed

    Wang, Lan; Zhang, Zhenyuan; Yu, Yi; Chen, Guangwei

    2017-07-20

    Isokinetic muscle strength training is presently the most advanced method of muscle strength training. However, the existing control schemes of the training equipment are usually limited to the structure of the brake. In order to solve this problem, this paper presents a solution to an isokinetic system based on the force control of a DC servomotor. A new fuzzy impedance nonlinear controller is designed by analyzing the relevant requirements of isokinetic motion. A series of force tracking comparison experiments between a fuzzy PI controller and a classical PI controller are studied. In addition, some strength training experiments employing different driving forces and target speeds are also conducted. The results demonstrate the effectiveness of this fuzzy impedance force tracking control strategy. Using the aforementioned methods, a comprehensive motion algorithm was designed.

  1. Work capacity during 30 days of bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Trowbridge, T. S.; Wade, C. E.

    1989-01-01

    Results are presented from a study to determine whether or not short-term variable intensity isotonic and intermittent high-intensity isokinetic short-duration leg exercise is effective for the maintenance of peak O2 (VO2) uptake and muscular strength and endurance, respectively, during 30 days of -6 deg head-down bed rest deconditioning. The results show no significant changes in leg peak torque, leg mean total work, arm total peak torque, or arm mean total work for members of the isotonic, isokinetic, and controls groups. Changes are observed, however, in peak VO2 levels. The results suggest that near-peak variabile intensity, isotonic leg excercise maintains peak VO2 during 30 days of bed rest, while peak intermittent, isokinetic leg excercise protocol does not.

  2. Using Evolved Fuzzy Neural Networks for Injury Detection from Isokinetic Curves

    NASA Astrophysics Data System (ADS)

    Couchet, Jorge; Font, José María; Manrique, Daniel

    In this paper we propose an evolutionary fuzzy neural networks system for extracting knowledge from a set of time series containing medical information. The series represent isokinetic curves obtained from a group of patients exercising the knee joint on an isokinetic dynamometer. The system has two parts: i) it analyses the time series input in order generate a simplified model of an isokinetic curve; ii) it applies a grammar-guided genetic program to obtain a knowledge base represented by a fuzzy neural network. Once the knowledge base has been generated, the system is able to perform knee injuries detection. The results suggest that evolved fuzzy neural networks perform better than non-evolutionary approaches and have a high accuracy rate during both the training and testing phases. Additionally, they are robust, as the system is able to self-adapt to changes in the problem without human intervention.

  3. Work capacity during 30 days of bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Trowbridge, T. S.; Wade, C. E.

    1989-01-01

    Results are presented from a study to determine whether or not short-term variable intensity isotonic and intermittent high-intensity isokinetic short-duration leg exercise is effective for the maintenance of peak O2 (VO2) uptake and muscular strength and endurance, respectively, during 30 days of -6 deg head-down bed rest deconditioning. The results show no significant changes in leg peak torque, leg mean total work, arm total peak torque, or arm mean total work for members of the isotonic, isokinetic, and controls groups. Changes are observed, however, in peak VO2 levels. The results suggest that near-peak variabile intensity, isotonic leg excercise maintains peak VO2 during 30 days of bed rest, while peak intermittent, isokinetic leg excercise protocol does not.

  4. Relationship between cardiopulmonary responses and isokinetic moments: the optimal angular velocity for muscular endurance.

    PubMed

    Lee, Chan-Bok; Eun, Denny; Kim, Kang-Ho; Park, Jae-Wan; Jee, Yong-Seok

    2017-04-01

    Most protocols for testing and rehabilitation for recovery and improvement of muscular endurance have been set at 180°/sec, 240°/sec, and 300°/sec. These protocols can cause confusion to clinical providers or other researchers. This study was aimed at investigating the optimal isokinetic angular speed for measuring or developing muscular endurance after assessing the relationship between cardiopulmonary responses and isokinetic moments. This study was conducted with 31 male and female college students. Graded exercise test and body composition were measured as well as the isokinetic moments of the knee muscles at three angular speeds: 180°/sec, 240°/sec, and 300°/sec. The specific isokinetic moments of knee muscles that were measured included: peak torque (PT) and total work (TW) on extensor (e) and flexor (f) of knee joints, which were denoted as ePT180, fPT180, eTW180, fTW180, ePT240, fPT240, eTW240, fTW240, ePT300, fPT300, eTW300, and fTW300 according to the three angular speeds. Spearman correlation test was used to examine the relationship between the sum means of cardiopulmonary responses and the variables of isokinetic moments. This study confirmed that the optimal angular speed for testing or training for muscular endurance was 180°/sec, which showed a stronger relationship between cardiopulmonary responses and isokinetic moments. Therefore, this angular speed is recommended for testing and training for muscular endurance of the knee joints.

  5. Relationship between cardiopulmonary responses and isokinetic moments: the optimal angular velocity for muscular endurance

    PubMed Central

    Lee, Chan-Bok; Eun, Denny; Kim, Kang-Ho; Park, Jae-Wan; Jee, Yong-Seok

    2017-01-01

    Most protocols for testing and rehabilitation for recovery and improvement of muscular endurance have been set at 180°/sec, 240°/sec, and 300°/sec. These protocols can cause confusion to clinical providers or other researchers. This study was aimed at investigating the optimal isokinetic angular speed for measuring or developing muscular endurance after assessing the relationship between cardiopulmonary responses and isokinetic moments. This study was conducted with 31 male and female college students. Graded exercise test and body composition were measured as well as the isokinetic moments of the knee muscles at three angular speeds: 180°/sec, 240°/sec, and 300°/sec. The specific isokinetic moments of knee muscles that were measured included: peak torque (PT) and total work (TW) on extensor (e) and flexor (f) of knee joints, which were denoted as ePT180, fPT180, eTW180, fTW180, ePT240, fPT240, eTW240, fTW240, ePT300, fPT300, eTW300, and fTW300 according to the three angular speeds. Spearman correlation test was used to examine the relationship between the sum means of cardiopulmonary responses and the variables of isokinetic moments. This study confirmed that the optimal angular speed for testing or training for muscular endurance was 180°/sec, which showed a stronger relationship between cardiopulmonary responses and isokinetic moments. Therefore, this angular speed is recommended for testing and training for muscular endurance of the knee joints. PMID:28503531

  6. Comparison of the Effects between Isokinetic and Isotonic Strength Training in Subacute Stroke Patients.

    PubMed

    Chen, Chen-Ling; Chang, Ken-Jie; Wu, Pei-Ying; Chi, Chun-Han; Chang, Shin-Tsu; Cheng, Yuan-Yang

    2015-06-01

    The goal of the study was to compare the effects of isokinetic and isotonic strengthening program on the changes of muscle strength, functional capacity, life quality, and inflammatory cytokines in hemiparetic patients within 6 months of stroke attack. Thirty-one participants were randomly assigned into either isotonic training group or isokinetic training group. Both training programs were carried out 5 days a week for a total of 4 weeks. Outcome measures included the peak isometric torque of knees at 90° flexion, the peak torque of knees extension and flexion at angular velocities 60°/s and 120°/s, Short Form 36 (SF-36) Health Survey Questionnaire, Timed Up and Go test, and inflammatory cytokines including high sensitivity C-reactive protein, interleukin-6, and tumor necrosis factor-α. Seven patients were not able to complete the training program and were excluded from our study. The results from the remaining 24 patients showed that there were more peak torque, and SF-36 items significantly improved in the isokinetic training group compared with the isotonic group. The Timed Up and Go test and interleukin-6 were improved in both groups, but tumor necrosis factor-α was improved in only the isokinetic group. There were no significant differences between the improvements of the 2 groups except the isokinetic flexion torque at 60°/s and 120°/s. Early strengthening exercise is important for subacute stroke patients, and isokinetic program, if accessible, can bring more significant benefits for them. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

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

    PubMed

    Zapparoli, Fabricio Yuri; Riberto, Marcelo

    2016-12-19

    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; 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. The objective of this study was 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 papers on the evaluation of hip flexor and/or extensor muscular strength with an isokinetic dynamometer and papers 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. On the databases 204 papers 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 papers obtained the best result in reproducibility and had their methodology analyzed. In order 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

  8. Associations of isokinetic knee steadiness with hop performance in patients with ACL deficiency.

    PubMed

    Pua, Yong-Hao; Ong, Peck-Hoon; Ho, Jia-Ying; Bryant, Adam L; E Webster, Kate; Clark, Ross A

    2015-08-01

    Contrary to the ample data available regarding the functional significance of isokinetic knee strength in patients with anterior cruciate ligament deficiency (ACLD), much less is known about the functional significance of isokinetic knee steadiness. This cross-sectional study aimed to evaluate, in patients with ACLD, the independent impact of isokinetic quadriceps and hamstrings torque steadiness on single-leg hop performance. Eighty-seven patients with unilateral ACLD participated. Patients performed isokinetic quadriceps and hamstrings steadiness and strength testing at 60°/s on an isokinetic dynamometer. Muscle steadiness and strength were represented by the wavelet-derived mean instantaneous frequency and peak value of the torque-time curves, respectively. To measure hop performance, patients performed a single-leg hop for distance and a 6-m single-leg hop for velocity. One of two patients [n = 45 (51 %)] had a 10 % or greater difference in knee torque frequency levels between the ACLD and contralateral knees. In multivariable models adjusted for age, sex, knee pain, and knee strength, hamstrings steadiness was significantly related with hop velocity whilst quadriceps steadiness was significantly related with both hop distance and velocity. Variance decomposition analyses suggested that quadriceps steadiness was similar in importance to hamstrings strength on hop distance and velocity. In patients with ACLD, isokinetic knee steadiness deficits were common and were independently associated with single-leg hop performance. Knee torque steadiness-a heretofore understudied variable-may prove a useful adjunct to conventional peak torque measurements by offering additional information to researchers and rehabilitation professionals about muscle performance and neuromuscular knee control. Prognostic studies, Level III.

  9. Hamstrings to quadriceps peak torque ratios diverge between sexes with increasing isokinetic angular velocity.

    PubMed

    Hewett, Timothy E; Myer, Gregory D; Zazulak, Bohdanna T

    2008-09-01

    Our purpose was to determine if females demonstrate decreased hamstrings to quadriceps peak torque (H/Q) ratios compared to males and if H/Q ratios increase with increased isokinetic velocity in both sexes. Maturation disproportionately increases hamstrings peak torque at high velocity in males, but not females. Therefore, we hypothesised that mature females would demonstrate decreased H/Q ratios compared to males and the difference in H/Q ratio between sexes would increase as isokinetic velocity increased. Studies that analysed the H/Q ratio with gravity corrected isokinetic strength testing reported between 1967 and 2004 were included in our review and analysis. Keywords were hamstrings/quadriceps, isokinetics, peak torque and gravity corrected. Medline and Smart databases were searched combined with cross-checked bibliographic reference lists of the publications to determine studies to be included. Twenty-two studies were included with a total of 1568 subjects (1145 male, 423 female). Males demonstrated a significant correlation between H/Q ratio and isokinetic velocity (R=0.634, p<0.0001), and a significant difference in the isokinetic H/Q ratio at the lowest angular velocity (47.8+/-2.2% at 30 degrees /s) compared to the highest velocity (81.4+/-1.1% at 360 degrees /s, p<0.001). In contrast, females did not demonstrate a significant relationship between H/Q ratio and isokinetic velocity (R=0.065, p=0.77) or a change in relative hamstrings strength as the speed increased (49.5+/-8.8% at 30 degrees /s; 51.0+/-5.7% at 360 degrees /s, p=0.84). Gender differences in isokinetic H/Q ratios were not observed at slower angular velocities. However, at high knee flexion/extension angular velocities, approaching those that occur during sports activities, significant gender differences were observed in the H/Q ratio. Females, unlike males, do not increase hamstrings to quadriceps torque ratios at velocities that approach those of functional activities.

  10. Relationships between maximal strength, muscle size, and myosin heavy chain isoform composition and postactivation potentiation.

    PubMed

    Seitz, Laurent B; Trajano, Gabriel S; Haff, G Gregory; Dumke, Charles C L S; Tufano, James J; Blazevich, Anthony J

    2016-05-01

    The purpose of this study was to examine the relationships between maximal voluntary postactivation potentiation (PAP) and maximal knee extensor torque, quadriceps cross-sectional area (CSA) and volume, and type II myosin heavy chain (MHC) isoform percentage in human skeletal muscle. Thirteen resistance-trained men completed a test protocol consisting of 2 isokinetic knee extensions at 180°·s(-)(1) performed before and 1, 4, 7, and 10 min after the completion of 4 maximal knee extensions at 60°·s(-)(1) (i.e., a conditioning activity (CA)). Magnetic resonance imaging and muscle microbiopsy procedures were completed on separate days to assess quadriceps CSA and volume and MHC isoform content. Maximal voluntary PAP response was assessed as the ratio of the highest knee extensor torques measured before and after the CA. There were large to very large correlations between maximal voluntary PAP response and maximal knee extensor torque (r = 0.62) and quadriceps CSA (r = 0.68) and volume (r = 0.63). Nonetheless, these correlations were not statistically significant after adjusting for the influence of type II MHC percentage using partial correlation analysis. By contrast, the strongest correlation was observed for type II MHC percentage (r = 0.77), and this correlation remained significant after adjusting for the other variables. Maximal voluntary PAP response is strongly correlated with maximal knee extensor torque and quadriceps CSA and volume, but is mostly clearly associated with the type II myosin isoform percentage in human skeletal muscle.

  11. How To: Maximize Google

    ERIC Educational Resources Information Center

    Branzburg, Jeffrey

    2004-01-01

    Google is shaking out to be the leading Web search engine, with recent research from Nielsen NetRatings reporting about 40 percent of all U.S. households using the tool at least once in January 2004. This brief article discusses how teachers and students can maximize their use of Google.

  12. Establishing isokinetic flow for a plasma torch exhaust gas diagnostic for a plasma hearth furnace

    SciTech Connect

    Pollack, Brian R.

    1996-05-01

    Real time monitoring of toxic metallic effluents in confined gas streams can be accomplished through use of Microwave Induced Plasmas to perform atomic emission spectroscopy, For this diagnostic to be viable it is necessary that it sample from the flowstream of interest in an isokinetic manner. A method of isokinetic sampling was established for this device for use in the exhaust system of a plasma hearth vitrification furnace. The flow and entrained particulate environment were simulated in the laboratory setting using a variable flow duct of the same dimensions (8-inch diameter, schedule 40) as that in the field and was loaded with similar particulate (less than 10 μm in diameter) of lake bed soil typically used in the vitrification process. The flow from the furnace was assumed to be straight flow. To reproduce this effect a flow straightener was installed in the device. An isokinetic sampling train was designed to include the plasma torch, with microwave power input operating at 2.45 GHz, to match local freestream velocities between 800 and 2400 ft/sec. The isokinetic sampling system worked as planned and the plasma torch had no difficulty operating at the required flowrates. Simulation of the particulate suspension was also successful. Steady particle feeds were maintained over long periods of time and the plasma diagnostic responded as expected.

  13. A study of isokinetic strength and laxity with and without anterior cruciate ligament injury

    PubMed Central

    Kim, Kewwan; Jeon, Kyoungkyu; Mullineaux, David R.; Cho, Eunok

    2016-01-01

    [Purpose] The purpose of this study was to provide useful information for future treatments and to organize rehabilitation programs for anterior cruciate ligament injury by assessing isokinetic muscle strength and laxity of knee joints in athletes with anterior cruciate ligament injuries. [Subjects and Methods] Thirty-one high school athletes with anterior cruciate ligament injuries participated in this study. Isokinetic muscle strength at 60°/sec and anterior cruciate ligament laxity for non-involved and involved sides, classified on the basis of the severity of anterior cruciate ligament injury, were assessed. [Results] A comparison of isokinetic muscle strength measured from the non-involved and involved sides showed a significant difference in the maximum strength and knee flexor muscle strength. For laxity, a significant difference was observed in the anterior drawer test results obtained with a force of 88 N. [Conclusion] In conclusion, this study has shown that the assessment of isokinetic muscle strength and ligament laxity from athletes with anterior cruciate ligament injury should be utilized to provide baseline data for prevention and prediction of injury. PMID:28174432

  14. Effect of isotonic and isokinetic exercise on muscle activity and balance of the ankle joint

    PubMed Central

    Kim, Mi-Kyoung; Yoo, Kyung-Tae

    2015-01-01

    [Purpose] This study was performed to examine how the balance of lower limbs and the muscle activities of the tibialis anterior (TA), the medial gastrocnemius (GCM), and the peroneus longus (PL) are influenced by isotonic and isokinetic exercise of the ankle joint. [Subjects] The subjects of this study were healthy adults (n=20), and they were divided into two groups (isotonic=10, isokinetic=10). [Methods] Isotonic group performed 3 sets of 10 contractions at 50% of MVIC and Isokinetic group performed 3 sets of 60°/sec. Muscle activity was measured by EMG and balance was measured by one-leg standing test. [Results] For muscle activity, a main effect of group was found in the non-dominant TA, and the dominant TA, GCM and PL. For balance, a main effect of time was found in both groups for the sway area measured support was provided by the non-dominant side. [Conclusion] In terms of muscle activity, the two groups showed a significant difference, and the isokinetic group showed higher muscle activities. In terms of balance, there was a significant difference between the pre-test and the post-test. The results of this study may help in the selection of exercises for physical therapy, because they show that muscle activity and balance vary according to the type of exercise. PMID:25729181

  15. An Analysis of Isotonic and Isokinetic Strength-Training Methods and Techniques.

    ERIC Educational Resources Information Center

    Metcalfe, Randall E.

    This annotated bibliography documents traditional isotonic strength training and nontraditional isotonic strength training (isokinetics) to aid the athletic coach in deciding which type and scheme of training will best develop strength. A glossary of terms is provided. Appendices include muscle action charts and tables, body position charts, a…

  16. Validity analysis of the Biodex System 3 dynamometer under static and isokinetic conditions.

    PubMed

    Zawadzki, Jerzy; Bober, Tadeusz; Siemieński, Adam

    2010-01-01

    Isokinetic dynamometers are frequently used as training devices. They are also regularly employed to measure the characteristics of skeletal muscles under dynamic conditions. The combination of published data of such measurements and the authors' own experience led to the present investigation of the validity of measurements performed using the Biodex System 3 dynamometer. Two individual dynamometers of the same type were used. A calibration technique was used to test the validity of measured torque and the angular coordinate of the position of the lever arm of the dynamometer under static conditions. The results of measurements performed under dynamic (isokinetic) conditions were verified by comparing numerical values of tests provided in the Biodex report and raw data collected directly from the measuring computer of the same isokinetic machine. The shapes of experimentally determined characteristics of torque Mmax(ω) and power P(ω) were also analysed, taking into consideration their conformity with the laws of thermodynamics and known properties of skeletal muscles. The static tests showed that the indications of the Biodex System 3 dynamometer lay within the error range specified by the manufacturer. Therefore, the results of static measurements can be considered accurate. According to the isokinetic tests, the values of angular velocity were also accurate. However, indications of torque and power were much less accurate, justifying the uncertainty over whether they can be considered true results of measurement.

  17. A Comparison of Isotonic, Isokinetic, and Plyometric Training Methods for Vertical Jump Improvement.

    ERIC Educational Resources Information Center

    Miller, Christine D.

    This annotated bibliography documents three training methods used to develop vertical jumping ability and power: isotonic, isokinetics, and plyometric training. Research findings on all three forms of training are summarized and compared. A synthesis of conclusions drawn from the annotated writings is presented. The report includes a glossary of…

  18. A study of isokinetic strength and laxity with and without anterior cruciate ligament injury.

    PubMed

    Kim, Kewwan; Jeon, Kyoungkyu; Mullineaux, David R; Cho, Eunok

    2016-12-01

    [Purpose] The purpose of this study was to provide useful information for future treatments and to organize rehabilitation programs for anterior cruciate ligament injury by assessing isokinetic muscle strength and laxity of knee joints in athletes with anterior cruciate ligament injuries. [Subjects and Methods] Thirty-one high school athletes with anterior cruciate ligament injuries participated in this study. Isokinetic muscle strength at 60°/sec and anterior cruciate ligament laxity for non-involved and involved sides, classified on the basis of the severity of anterior cruciate ligament injury, were assessed. [Results] A comparison of isokinetic muscle strength measured from the non-involved and involved sides showed a significant difference in the maximum strength and knee flexor muscle strength. For laxity, a significant difference was observed in the anterior drawer test results obtained with a force of 88 N. [Conclusion] In conclusion, this study has shown that the assessment of isokinetic muscle strength and ligament laxity from athletes with anterior cruciate ligament injury should be utilized to provide baseline data for prevention and prediction of injury.

  19. Effect of isokinetic training on muscle strength and postural balance in children with Down's syndrome.

    PubMed

    Eid, Mohamed A; Aly, Sobhy M; Huneif, Mohamed A; Ismail, Dina K

    2017-06-01

    Children with Down's syndrome (DS) often have greater postural sway and delay in motor development. Muscle weakness and hypotonia, particularly of the lower extremities, are theorized to impair their overall physical health and ability to perform daily activities. Therefore, the aim of this study was to investigate the effects of isokinetic training on muscle strength and postural balance in children with DS. Thirty-one children with DS ranging in age from 9 to 12 years were assigned randomly into two groups. The control group received the conventional physical therapy, whereas the study group received the same therapy as the control group in addition to the isokinetic training 3 days a week for 12 weeks. Measurement of stability indices using the Biodex Stability System as well as peak torque of knee flexors and extensors of both sides using the isokinetic dynamometer was performed before and after 12 weeks of the treatment program. Each group showed significant improvements in postural balance and peak torque of knee flexors and extensors (P<0.05), with significantly greater improvements observed in the study group compared with the control group (P<0.05). These outcomes indicated that participation in the isokinetic training program induced greater improvements in muscle strength and postural balance in children with DS.

  20. Comparitive Assessment of Isokinetic and Pneumatic Lower Limb Strength in Functionally-Limited Elderly Subjects

    USDA-ARS?s Scientific Manuscript database

    The purpose of this study was to investigate the relationship between isokinetic and pneumatic knee extensor strength in functionally-limited elders and to compare the respective changes in knee extensor peak torque and one repetition maximum strength (1RM) after a randomized controlled progressive ...

  1. Knee Extensor and Flexor Torque Development with Concentric and Eccentric Isokinetic Training

    ERIC Educational Resources Information Center

    Miller, Larry E.; Pierson, Lee M.; Nickols-Richardson, Sharon M.; Wootten, David F.; Selmon, Serah E.; Ramp, Warren K.; Herbert, William G.

    2006-01-01

    This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training…

  2. Knee Extensor and Flexor Torque Development with Concentric and Eccentric Isokinetic Training

    ERIC Educational Resources Information Center

    Miller, Larry E.; Pierson, Lee M.; Nickols-Richardson, Sharon M.; Wootten, David F.; Selmon, Serah E.; Ramp, Warren K.; Herbert, William G.

    2006-01-01

    This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training…

  3. An Analysis of Isotonic and Isokinetic Strength-Training Methods and Techniques.

    ERIC Educational Resources Information Center

    Metcalfe, Randall E.

    This annotated bibliography documents traditional isotonic strength training and nontraditional isotonic strength training (isokinetics) to aid the athletic coach in deciding which type and scheme of training will best develop strength. A glossary of terms is provided. Appendices include muscle action charts and tables, body position charts, a…

  4. Effect of isotonic and isokinetic exercise on muscle activity and balance of the ankle joint.

    PubMed

    Kim, Mi-Kyoung; Yoo, Kyung-Tae

    2015-02-01

    [Purpose] This study was performed to examine how the balance of lower limbs and the muscle activities of the tibialis anterior (TA), the medial gastrocnemius (GCM), and the peroneus longus (PL) are influenced by isotonic and isokinetic exercise of the ankle joint. [Subjects] The subjects of this study were healthy adults (n=20), and they were divided into two groups (isotonic=10, isokinetic=10). [Methods] Isotonic group performed 3 sets of 10 contractions at 50% of MVIC and Isokinetic group performed 3 sets of 60°/sec. Muscle activity was measured by EMG and balance was measured by one-leg standing test. [Results] For muscle activity, a main effect of group was found in the non-dominant TA, and the dominant TA, GCM and PL. For balance, a main effect of time was found in both groups for the sway area measured support was provided by the non-dominant side. [Conclusion] In terms of muscle activity, the two groups showed a significant difference, and the isokinetic group showed higher muscle activities. In terms of balance, there was a significant difference between the pre-test and the post-test. The results of this study may help in the selection of exercises for physical therapy, because they show that muscle activity and balance vary according to the type of exercise.

  5. A Comparison of Isotonic, Isokinetic, and Plyometric Training Methods for Vertical Jump Improvement.

    ERIC Educational Resources Information Center

    Miller, Christine D.

    This annotated bibliography documents three training methods used to develop vertical jumping ability and power: isotonic, isokinetics, and plyometric training. Research findings on all three forms of training are summarized and compared. A synthesis of conclusions drawn from the annotated writings is presented. The report includes a glossary of…

  6. Isokinetic Leg Flexion and Extension Strength of Elite Adolescent Female Track and Field Athletes.

    ERIC Educational Resources Information Center

    Housh, Terry J.; And Others

    1984-01-01

    Adolescent female track-and-field athletes were measured to compare isokinetic strength of leg flexion and extension movements. Throwers, jumpers, middle-distance runners, and sprinters participated in the study. Throwers were found to be stronger in absolute strength, but there were no significant differences in relative strength. Results are…

  7. Assessment of evertor weakness in patients with chronic ankle instability: Functional versus isokinetic testing.

    PubMed

    Terrier, Romain; Degache, Francis; Fourchet, François; Gojanovic, Boris; Forestier, Nicolas

    2017-01-01

    Ankle sprain is the most common sport-related injury and eccentric weakness of ankle evertors is regarded as a significant muscular deficit related to chronic ankle instability. However, the eccentric performance of the evertors is rarely assessed by clinicians because procedures used for research purposes (i.e. isokinetic tests) are not easily applicable in daily practice. The present study assessed the ability of two different testing procedures to distinguish between groups of 12 healthy subjects or 12 patients suffering from chronic ankle instability. On the one hand, the strength of evertors was assessed with a goldstandard isokinetic procedure. On the other hand, we assessed the ability of the subjects to control ankle inversion during weight bearing (functional standing test). Data showed no significant difference between groups for isokinetic peak torque values normalized to body weight. Conversely, the functional test revealed a significantly impaired ability to control ankle inversion during weight bearing in subjects with chronic ankle instability. This suggests that this easy-to-apply functional test is better suited compared to isokinetic testing procedures to assess weakness of evertors in patients suffering from chronic ankle instability. Moreover, this test may also be used to objectively monitor improvements during rehabilitation or progression in prevention protocols. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. A Methodologic Approach for Normalizing Angular Work and Velocity During Isotonic and Isokinetic Eccentric Training

    PubMed Central

    Guilhem, Gaël; Cornu, Christophe; Guével, Arnaud

    2012-01-01

    Context: Resistance exercise training commonly is performed against a constant external load (isotonic) or at a constant velocity (isokinetic). Researchers comparing the effectiveness of isotonic and isokinetic resistance-training protocols need to equalize the mechanical stimulus (work and velocity) applied. Objective: To examine whether the standardization protocol could be adjusted and applied to an eccentric training program. Design: Controlled laboratory study. Setting: Controlled research laboratory. Patients or Other Participants: Twenty-one sport science male students (age = 20.6 ± 1.5 years, height = 178.0 ± 4.0 cm, mass = 74.5 ± 9.1 kg). Intervention(s): Participants performed 9 weeks of isotonic (n = 11) or isokinetic (n = 10) eccentric training of knee extensors that was designed so they would perform the same amount of angular work at the same mean angular velocity. Main Outcome Measure(s): Angular work and angular velocity. Results: The isotonic and isokinetic groups performed the same total amount of work (−185.2 ± 6.5 kJ and −184.4 ± 8.6 kJ, respectively) at the same angular velocity (21 ± 1°/s and 22°/s, respectively) with the same number of repetitions (8.0 and 8.0, respectively). Bland-Altman analysis showed that work (bias = 2.4%) and angular velocity (bias = 0.2%) were equalized over 9 weeks between the modes of training. Conclusions: The procedure developed allows angular work and velocity to be standardized over 9 weeks of isotonic and isokinetic eccentric training of the knee extensors. This method could be useful in future studies in which researchers compare neuromuscular adaptations induced by each type of training mode with respect to rehabilitating patients after musculoskeletal injury. PMID:22488276

  9. A methodologic approach for normalizing angular work and velocity during isotonic and isokinetic eccentric training.

    PubMed

    Guilhem, Gaël; Cornu, Christophe; Guével, Arnaud

    2012-01-01

    Resistance exercise training commonly is performed against a constant external load (isotonic) or at a constant velocity (isokinetic). Researchers comparing the effectiveness of isotonic and isokinetic resistance-training protocols need to equalize the mechanical stimulus (work and velocity) applied. To examine whether the standardization protocol could be adjusted and applied to an eccentric training program. Controlled laboratory study. Controlled research laboratory. Twenty-one sport science male students (age = 20.6 ± 1.5 years, height = 178.0 ± 4.0 cm, mass = 74.5 ± 9.1 kg). Participants performed 9 weeks of isotonic (n = 11) or isokinetic (n = 10) eccentric training of knee extensors that was designed so they would perform the same amount of angular work at the same mean angular velocity. Angular work and angular velocity. The isotonic and isokinetic groups performed the same total amount of work (-185.2 ± 6.5 kJ and -184.4 ± 8.6 kJ, respectively) at the same angular velocity (21 ± 1°/s and 22°/s, respectively) with the same number of repetitions (8.0 and 8.0, respectively). Bland-Altman analysis showed that work (bias = 2.4%) and angular velocity (bias = 0.2%) were equalized over 9 weeks between the modes of training. The procedure developed allows angular work and velocity to be standardized over 9 weeks of isotonic and isokinetic eccentric training of the knee extensors. This method could be useful in future studies in which researchers compare neuromuscular adaptations induced by each type of training mode with respect to rehabilitating patients after musculoskeletal injury.

  10. Limitations of Isokinetic Testing to Determine Shoulder Strength after Rotator Cuff Repair

    PubMed Central

    Yen, David

    2005-01-01

    Some investigators have reported incomplete data when using isokinetic testing as a means of analyzing shoulder strength after rotator cuff repair. An explanation provided has been that the subjects could not reach the speed at which the machine was set. The purpose of this study was to determine if strength data could be generated for all motions being tested by using not only the one or two speeds employed by others, but three speeds across the spectrum of those available. Inclusion criteria were a minimum of two years since surgery with a normal contralateral shoulder. All eligible subjects had isokinetic testing of the non-operated shoulder followed by the operated shoulder, in flexion, abduction and external rotation, tested at 60°, 120° and 180° per second. Fourteen patients were eligible and tested. Isokinetic data showed deficiencies in strength in the operated shoulder compared to the opposite side for abduction, external rotation and flexion of 14%, 27% and 20% respectively. In 10/123 (8%) of the tests, the patients could not reach the preset velocity to yield valid data. One patient could not place and maintain the operated arm in the test position of 90° of shoulder abduction. There was a significant deficiency in abduction at only one of three speeds. This study confirms that isokinetic testing is a powerful tool that lends itself well to producing objective data on shoulder strength after rotator cuff repair, but it also has the limitation that some patients cannot reach the preset velocity for some motions, or place and maintain the operated arm in the test position for the movements being tested. Therefore, to optimize the chances of obtaining isokinetic data for all movements after rotator cuff repair, we suggest using speeds for all motions and consideration of scapular, frontal and sagittal planes for testing. PMID:16089087

  11. Limitations of isokinetic testing to determine shoulder strength after rotator cuff repair.

    PubMed

    Yen, David

    2005-01-01

    Some investigators have reported incomplete data when using isokinetic testing as a means of analyzing shoulder strength after rotator cuff repair. An explanation provided has been that the subjects could not reach the speed at which the machine was set. The purpose of this study was to determine if strength data could be generated for all motions being tested by using not only the one or two speeds employed by others, but three speeds across the spectrum of those available. Inclusion criteria were a minimum of two years since surgery with a normal contralateral shoulder. All eligible subjects had isokinetic testing of the non-operated shoulder followed by the operated shoulder, in flexion, abduction and external rotation, tested at 60 degrees, 120 degrees and 180 degrees per second. Fourteen patients were eligible and tested. Isokinetic data showed deficiencies in strength in the operated shoulder compared to the opposite side for abduction, external rotation and flexion of 14%, 27% and 20% respectively. In 10/123 (8%) of the tests, the patients could not reach the preset velocity to yield valid data. One patient could not place and maintain the operated arm in the test position of 90 degrees of shoulder abduction. There was a significant deficiency in abduction at only one of three speeds. This study confirms that isokinetic testing is a powerful tool that lends itself well to producing objective data on shoulder strength after rotator cuff repair, but it also has the limitation that some patients cannot reach the preset velocity for some motions, or place and maintain the operated arm in the test position for the movements being tested. Therefore, to optimize the chances of obtaining isokinetic data for all movements after rotator cuff repair, we suggest using speeds for all motions and consideration of scapular, frontal and sagittal planes for testing.

  12. The isokinetic strength profile of elite soccer players according to playing position.

    PubMed

    Śliwowski, Robert; Grygorowicz, Monika; Hojszyk, Radosław; Jadczak, Łukasz

    2017-01-01

    The aim of this study was to compare isokinetic strength performance profiles in elite soccer players across different field positions. A total of 111 elite international players of Polish Ekstraklasa (the top division in Poland) were examined during the 2010-2015 seasons. The players were classified into six positional roles: central defenders (CD), external defenders (ED), central midfielders (CM), external midfielders (EM), forwards (F), and goalkeepers (G). The concentric isokinetic strength (peak torque [PT] of quadriceps and hamstrings, H/Q ratios) was calculated for the dominant leg and the non-dominant leg at angular velocity of 1.05 rad ·s-1, whereas to assess isokinetic muscle endurance, the total work [TW] at angular velocity of 4.19 rad ·s-1, was taken into consideration. The results showed that isokinetic strength performance varies significantly among players in different playing positions. The analysis of PT for quadriceps (PT-Q) and hamstrings (PT-H) generally showed that the goalkeepers and central midfielders had lower strength levels compared to other playing positions. In the case of PT-H and hamstring/quadricep (H/Q) peak torque ratios, statistically significant differences were also noted for the legs, where mean values noted for the dominant leg were higher than for the non-dominant leg. For TW for quadriceps (TW-Q) and hamstrings (TW-H), statistically significant differences were noted only between playing positions. TW-Q values for goalkeepers were lower than for central defenders and external midfielders. TW-H values for goalkeepers were lower than for central midfielders, central defenders and external midfielders. This study showed that specific functional activity of players in individual positions on the field influences the varied profile of isokinetic strength performance.

  13. Vitamin D concentration in 342 professional football players and association with lower limb isokinetic function.

    PubMed

    Hamilton, Bruce; Whiteley, Rod; Farooq, Abdulaziz; Chalabi, Hakim

    2014-01-01

    This study aimed to evaluate both the epidemiology of Vitamin D deficiency in Qatar-based footballers originating from a variety of countries and the existence of any relationship between 25 hydroxy-cholecalciferol (25(OH)D) concentration and lower limb isokinetic performance (peak torque) in well trained professional football players. Cross-sectional clinical. Three hundred and forty-two professional footballers based in Qatar were evaluated as part of their routine annual medical assessment. History, examination, blood tests and a lower limb isokinetic evaluation were performed. Association between 25(OH)D concentrations and lower limb isokinetic peak torque was assessed. Eighty four percent of players had 25(OH)D concentrations less than 30 ng/ml; 12% were severely deficient (<10 ng/ml) and there was a significant difference in 25(OH)D level depending on the country of origin of the player. Total body mass and lean mass was significantly higher in players with 25(OH)D levels greater than 20 ng/ml, when compared with the less than 10 ng/ml group. There was no consistent association found between lower limb isokinetic peak torque and 25(OH)D concentration. 25(OH)D deficiency is highly prevalent in Qatar based footballers. Severe 25(OH)D deficiency is associated with lower body mass, and lower lean mass, when compared with footballers with concentrations >20 ng/ml. Vitamin D deficiency was not shown to have a consistent association with lower limb isokinetic peak torque and both the clinical and performance related significance of this high prevalence of Vitamin D deficiency remains unclear. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  14. Contribution of isokinetic muscle strengthening in the rehabilitation of obese subjects.

    PubMed

    Ghroubi, Sameh; Kossemtini, Wassia; Mahersi, Sawssan; Elleuch, Wafa; Chaabene, Mokhtar; Elleuch, Mohamed Habib

    2016-04-01

    Our objective was to evaluate the specific effect of isokinetic muscle strength enhancement in the rehabilitation of obese subjects by comparing two groups (isokinetic muscle exercising associated with aerobic exercising or only aerobic exercising). This was a randomized, prospective study from January 2008 to December 2009 involving 40 obese patients randomized into two groups. The first group G1 (n=20) followed a program of aerobic training and isokinetic exercising of the extensor and flexor muscles of lower limbs and spine. The second group G2 (n=20) followed only a program of aerobic exercising. All patients completed their rehabilitation protocols comprising 3 sessions per week for two months. The parameters evaluated before and after the program were anthropometric parameters (weight, stature, body mass index, body fat and lean body mass percentages), cardiovascular parameters by stress test on electromagnetic ergo-cycle, an assessment of muscle strength by isokinetic dynamometer and an assessment of psychological status and quality of life. We recruited 36 women and 4 men. Initially, the 2 groups were comparable. After training, in both groups we noted an improvement in anthropometric parameters, with an average weight loss of 1.83 kg/week (P<0.001), an improvement in cardiovascular parameters with a decrease in heart rate at rest and under effort, and in systolic and diastolic arterial blood pressure values at rest and under effort (P<0.01 in both group), an improvement in parameters of muscle strength with increase in moment of maximum strength of extensor and flexor knee and spine muscles for all three test speeds, and an improvement in psychological status and in quality of life. The improvement of all these parameters was statistically greater in G1 (P<0.05). Isokinetic muscle strengthening increases the effects of aerobic exercising in the obese by improving muscle strength, increasing lean body mass and reducing body fat. Copyright © 2016 Elsevier

  15. RELATIONSHIP BETWEEN ISOKINETIC KNEE STRENGTH AND JUMP CHARACTERISTICS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION.

    PubMed

    Laudner, Kevin; Evans, Daniel; Wong, Regan; Allen, Aaron; Kirsch, Tom; Long, Brian; Meister, Keith

    2015-06-01

    Clinicians are often challenged when making return-to-play decisions following anterior cruciate ligament reconstruction (ACL-R). Isokinetic strength and jump performance testing are common tools used to make this decision. Unfortunately, vertical jump performance standards have not been clearly established and many clinicians do not have access to isokinetic testing equipment. To establish normative jump and strength characteristics in ACL-R patients cleared by an orthopedic physician to return-to-play and to determine if relationships exist between knee isokinetic strength measurements and jump characteristics described using an electronic jump map system. Descriptive laboratory study. Thirty-three ACL-R patients who had been cleared to return to athletic competition participated in this study. Twenty-six of these ACL-R participants were also matched to 26 asymptomatic athletes based on sex, limb, height, and mass to determine isokinetic strength and jump characteristic differences between groups. Jump tests consisted of single leg vertical, double leg vertical, and a 4-jump single leg vertical jump assessed using an electronic jump mat system. Independent t-tests were used to determine differences between groups and multiple regression analyses were used to identify any relationships between jump performance and knee strength (p<0.05). The ACL-R group had lower vertical jump capabilities and some bilateral knee strength deficiencies compared to the matched control group. The ACL-R group also showed several moderate-to-strong positive relationships for both knee extension and flexion strength with several jump performance characteristics, such as single and double leg vertical jump height. The current results indicate that ACL-R patients present with several knee strength and vertical jump differences compared to a matched control group at the time of return-to-play. Also, ACL-R patient's performance on an electronic jump mat system is strongly related to

  16. The isokinetic strength profile of elite soccer players according to playing position

    PubMed Central

    Grygorowicz, Monika; Hojszyk, Radosław; Jadczak, Łukasz

    2017-01-01

    The aim of this study was to compare isokinetic strength performance profiles in elite soccer players across different field positions. A total of 111 elite international players of Polish Ekstraklasa (the top division in Poland) were examined during the 2010–2015 seasons. The players were classified into six positional roles: central defenders (CD), external defenders (ED), central midfielders (CM), external midfielders (EM), forwards (F), and goalkeepers (G). The concentric isokinetic strength (peak torque [PT] of quadriceps and hamstrings, H/Q ratios) was calculated for the dominant leg and the non-dominant leg at angular velocity of 1.05 rad ·s–1, whereas to assess isokinetic muscle endurance, the total work [TW] at angular velocity of 4.19 rad ·s–1, was taken into consideration. The results showed that isokinetic strength performance varies significantly among players in different playing positions. The analysis of PT for quadriceps (PT-Q) and hamstrings (PT-H) generally showed that the goalkeepers and central midfielders had lower strength levels compared to other playing positions. In the case of PT-H and hamstring/quadricep (H/Q) peak torque ratios, statistically significant differences were also noted for the legs, where mean values noted for the dominant leg were higher than for the non-dominant leg. For TW for quadriceps (TW-Q) and hamstrings (TW-H), statistically significant differences were noted only between playing positions. TW-Q values for goalkeepers were lower than for central defenders and external midfielders. TW-H values for goalkeepers were lower than for central midfielders, central defenders and external midfielders. This study showed that specific functional activity of players in individual positions on the field influences the varied profile of isokinetic strength performance. PMID:28759603

  17. Isokinetic evaluation of wrist muscle strength in patients of carpal tunnel syndrome.

    PubMed

    Ağırman, Mehmet; Kara, Adnan; Durmuş, Oğuz; Saral, İlknur; Çakar, Engin

    2017-04-01

    This study aims to investigate the isokinetic characteristics of wrist strength in flexion, extension, supination, pronation, radial, and ulnar deviation in patients with moderate or severe carpal tunnel syndrome (CTS). Thirteen patients (23 hands) (2 males, 11 females; mean age 45 years; range 29 to 60 years) with moderate or severe CTS were compared to six healthy control subjects (12 hands) (2 males, 4 females; mean age 41 years; range 27 to 63 years) in this study, which was conducted between January 2016 and April 2016. Wrist flexion, extension, supination, pronation, radial, and ulnar deviation muscle strengths were measured at 30°/second (5 sets) angular velocity with isokinetic dynamometer. Grip strength was measured with hand dynamometer (kilograms). Boston Questionnaire was used for clinical assessment. Grip strength (p=0.003); wrist flexion 30°/second (p=0.014); extension 30°/second (p=0.016); and ulnar deviation 30°/second (p=0.017) muscle strengths were lower in CTS patients compared with the control group. An evaluation according to symptom duration did not reveal any significant relationship in any of the isokinetic tests with the exception of pronation 30°/second (p=0.039, r= -0.432) and ulnar deviation 30°/second (p=0.034, r=0.443) in CTS patients. No significant relationship was found between Boston Questionnaire, grip strength, and isokinetic test results. Quantitative wrist strength measurements with isokinetic dynamometers are beneficial in conservative exercise treatments and motor assessments of CTS patients.

  18. Quantum-Inspired Maximizer

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    2008-01-01

    A report discusses an algorithm for a new kind of dynamics based on a quantum- classical hybrid-quantum-inspired maximizer. The model is represented by a modified Madelung equation in which the quantum potential is replaced by different, specially chosen 'computational' potential. As a result, the dynamics attains both quantum and classical properties: it preserves superposition and entanglement of random solutions, while allowing one to measure its state variables, using classical methods. Such optimal combination of characteristics is a perfect match for quantum-inspired computing. As an application, an algorithm for global maximum of an arbitrary integrable function is proposed. The idea of the proposed algorithm is very simple: based upon the Quantum-inspired Maximizer (QIM), introduce a positive function to be maximized as the probability density to which the solution is attracted. Then the larger value of this function will have the higher probability to appear. Special attention is paid to simulation of integer programming and NP-complete problems. It is demonstrated that the problem of global maximum of an integrable function can be found in polynomial time by using the proposed quantum- classical hybrid. The result is extended to a constrained maximum with applications to integer programming and TSP (Traveling Salesman Problem).

  19. Functional performance, maximal strength, and power characteristics in isometric and dynamic actions of lower extremities in soccer players.

    PubMed

    Requena, Bernardo; González-Badillo, Juan José; de Villareal, Eduardo Saez Saez; Ereline, Jaan; García, Inmaculada; Gapeyeva, Helena; Pääsuke, Mati

    2009-08-01

    The purposes of the present study were to determine muscle strength and power output characteristics in a group of professional soccer players and to identify their relationships with 2 functional performance tests (vertical jumping height and 15-m sprint time). Maximal strength and power indices attained against different loads in barbell back squat exercise, isometric maximal force of the knee extensor and plantar flexor muscles, isokinetic peak torque of the knee extensors muscles, vertical jumping height in squat and counter-movement jumps, and 15-m sprint time tests were assessed in 21 semiprofessional soccer players (age 20 +/- 3.8 years). Correlation analyses were performed to examine the relationship between each of these measures. The main results of the present study were that (a) maximal power in concentric half-squat exercise was attained with a load of 60% of 1 repetition maximum, representing 112% of body weight; (b) the performance in the functional tests selected was significantly related with all the half-squat variables measured, especially with loads of 75-125% of body weight; and (c) low to nonsignificant correlations were found between functional tests performance and isometric and isokinetic muscle strength measures. It was concluded that in semiprofessional soccer players (a) isometric and isokinetic muscle strength assessed in an open kinetic chain were not movement-specific enough to predict performance during a more complex movement, such as jump or sprint and (b) concentric half-squat exercise was principally related with the functional tests selected when it was performed against external loading within the range of the load in case of which the maximal power output was attained.

  20. Obtaining reliable measurements of knee extensor torque produced during maximal voluntary contractions: an experimental investigation.

    PubMed

    Kues, J M; Rothstein, J M; Lamb, R L

    1992-07-01

    The purpose of this study was to develop and test a protocol that could be used to obtain reliable measurements of knee extensor torque produced during maximal voluntary contractions. On each of 3 days, 10 subjects performed six consecutive maximal voluntary contractions, in the same randomized order, for each of the following 10 conditions: concentric isokinetic contractions at velocities of 30 degrees, 90 degrees, 120 degrees, and 180 degrees/s; eccentric isokinetic contractions at velocities of 30 degrees, 90 degrees, 120 degrees, and 180 degrees/s; and isometric contractions at 40 and 60 degrees of knee flexion. The peak torques produced were examined to determine on which day and during which contraction subjects produced the greatest torques for each condition. This information was used to develop a practice protocol. Fifteen different subjects were tested following this protocol. Subjects participated in two practice sessions, a test session, and a retest session. Intraclass correlation coefficients (ICCs) were calculated to determine the degree of agreement between torques for the test and retest sessions. The ICCs ranged from .87 to .98. The protocol developed appears to be useful for obtaining reliable measurements of knee extensor torque.

  1. Muscle fatigue experienced during maximal eccentric exercise is predictive of the plasma creatine kinase (CK) response.

    PubMed

    Hody, S; Rogister, B; Leprince, P; Wang, F; Croisier, J-L

    2013-08-01

    Unaccustomed eccentric exercise may cause skeletal muscle damage with an increase in plasma creatine kinase (CK) activity. Although the wide variability among individuals in CK response to standardized lengthening contractions has been well described, the reasons underlying this phenomenon have not yet been understood. Therefore, this study investigated a possible correlation of the changes in muscle damage indirect markers after an eccentric exercise with the decline in muscle performance during the exercise. Twenty-seven healthy untrained male subjects performed three sets of 30 maximal isokinetic eccentric contractions of the knee extensors. The muscular work was recorded using an isokinetic dynamometer to assess muscle fatigue by means of various fatigue indices. Plasma CK activity, muscle soreness, and stiffness were measured before (pre) and one day after (post) exercise. The eccentric exercise bout induced significant changes of the three muscle damage indirect markers. Large inter-subject variability was observed for all criteria measured. More interestingly, the log (CK(post) /CK(pre)) and muscle stiffness appeared to be closely correlated with the relative work decrease (r = 0.84, r(2)  = 0.70 and r = 0.75, r(2)  = 0.56, respectively). This is the first study to propose that the muscle fatigue profile during maximal eccentric protocol could predict the magnitude of the symptoms associated with muscle damage in humans. © 2011 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Effect of 12-week isokinetic training on muscle strength in adult with healed thermal burn.

    PubMed

    Ebid, Anwar A; Omar, Mohammed T A; Abd El Baky, Amal M

    2012-02-01

    Severe burns result in marked and prolonged skeletal muscle catabolism and weakness, which persist despite 'standard" rehabilitation programmes of occupational and physical therapy. Therefore, the objectives of this study were of twofold: to quantify the long-term effects of burns on leg muscle strength and to assess whether adults with thermal burn would benefit from the isokinetic training programme. Burned adult patients, with 35-55% total body surface area (TBSA) burned, were assessed at 6 months after burn in respect to leg muscle strength at 150° s(-1), using isokinetic dynamometry. Non-burned adults were assessed similarly, and served as controls. The burned adults participated in the resistance training programme 3 times weekly. The isokinetic exercise programme was begun with 60% of the average peak torque. Intensity of isokinetic exercise was increased from one set to five sets during the first through fifth sessions and remained at six sets for the remaining 6th to 24th sessions. Finally, a dose of 10 sets was applied for the 25th to the 36th sessions. Each set consisted of five repetitions of concentric contraction in angular velocities of 150° s(-1) for knee extensors, and flexors. All exercise sessions were preceded by a 5-min warm-up period on the treadmill. Subjects with burns more than 35% of TBSA produced significantly less torque, work, and power in the quadriceps and hamstring than control subjects (20.5%, 15.2%, p<0.05). Three months after isokinetic programme, muscle strength further increased by 17.9%±10.1% compared to the baseline measurement for burned patients but continued to be below the concurrent age-matched, non-burned adult. We found that adults with severe burns, relative to non-burned adults, had significantly lower peak torque as well as total work performance using the extensors and flexors muscles of the thigh. Participation in isokinetic training resulted in a greater improvement in extensor and flexor muscle strength in

  3. Effect of isokinetic training on muscle strength, size and gait after healed pediatric burn: a randomized controlled study.

    PubMed

    Ebid, Anwar Abdelgayed; El-Shamy, Shamekh Mohamed; Draz, Amira Hussin

    2014-02-01

    The aim of this study was to investigate the effects of isokinetic training program on muscle strength, muscle size and gait parameters after healed pediatric burn. Randomized controlled trial. Thirty three pediatric burned patients with circumferential lower extremity burn with total body surface area (TBSA) ranging from 36 to 45%, and ages from 10 to 15 years participated in the study and were randomized into isokinetic group and a control group. Non-burned healthy pediatric subjects were assessed similarly to burned subjects and served as matched healthy controls. Patients in the isokinetic group (n=16) participated in the isokinetic training program for 12 weeks for quadriceps dominant limb, 3 times per week, at angular velocity 150°/s, concentric mode of contraction, time rest between each set for 3 min, 3 sets/day and control group (n=17) participated in home based physical therapy exercise program without isokinetic. Assessment of quadriceps strength by isokinetic dynamometer, quadriceps size and gait parameters were performed at baseline and at the end of the training period for both groups. Patients in isokinetic group showed a significant improvement in quadriceps strength, quadriceps size and gait parameters as compared with those in the control group. Quadriceps strength and percentage of improvement was 79.25 ± 0.93 Nm (68.40%) for isokinetic group and 51.88 ± 1.31 Nm (9.84%) for the control group. Quadriceps size and percentage of improvement was 31.50 ± 0.89 cm (7.47%) for isokinetic group and 29.26 ± 1.02 cm (1.02%) for the control group. Stride length, step length, velocity and cadence and percentage of improvement for isokinetic group was 135.50 ± 2.82 (53.97%), 63.25 ± 2.97 (63.77%), 135.94 ± 1.65 (81.42%), 137.63 ± 1.36 (66.96%) and for the control group was 94.00 ± 2.69 (6.68%), 43.76 ± 1.34 (15.15%), 81.11 ± 1.91 (8.6%), 90.35 ± 1.32 (9.01%) respectively. Participation in the isokinetic training program resulted in a greater

  4. Lack of gender differences in the ability to relax between repetitive maximum isokinetic shoulder forward flexions: a population-based study among northern Swedes.

    PubMed

    Elert, J; Sterner, Y; Nyberg, V; Gerdle, B

    2000-11-01

    The aim of the present study was to analyse the effects of gender and age in a population-based sample of clinically healthy subjects on: (1) strength, endurance and perception of fatigue, (2) mean frequency (MNF) of the electromyogram (EMG), and (3) the ability to relax between active contractions (signal amplitude ratio; SAR) of the surface EMG of an isokinetic shoulder forward flexion test. With this aim we have analysed aspects of the validity of MNF as an indicator of fatigue, using peak torque as a criterion variable. The subjects were 27 men and 28 women (age range: 20-60 years), who were obtained by random sample from the official census lists (participation rate: 66%). The peak torque and surface EMG of two portions of the trapezius, deltoid and infraspinatus muscles were recorded throughout 100 repetitive maximal isokinetic shoulder forward flexions. No significant differences in the perception of fatigue and relative endurance levels of peak torque and work were found between males and females. Males were significantly stronger than females and, on average, females produced approximately 60% of the output of the males; 76% after normalisation for body mass. The men had significantly lower MNF endurance levels for three of the investigated muscles. When controlled for age and body mass, the men had a significantly higher MNF of the deltoid muscle than did the females. These differences were only found for the deltoid muscle. Significant correlations existed between the MNF of the four muscles and biomechanical output, indicating criterion validity for the MNF variable with respect to fatigue. There were no significant effects of gender or age on the ability to relax between repetitive contractions (SAR). The higher prevalence of musculoskeletal complaints of the neck-shoulder region in females cannot be explained by a higher intrinsic muscle tension. Age, gender, body mass index and biomechanical output can have significant effects upon MNF. These effects

  5. The effect of 4 weeks beta-alanine supplementation and isokinetic training on carnosine concentrations in type I and II human skeletal muscle fibres.

    PubMed

    Kendrick, Iain P; Kim, Hyo Jeong; Harris, Roger Charles; Kim, Chang Keun; Dang, Viet H; Lam, Thanh Q; Bui, Toai T; Wise, John A

    2009-05-01

    Seven male students were supplemented with beta-alanine (beta-ALG) for 4 weeks (6.4 g day(-1)) and seven with a matching placebo (PLG). Subjects undertook 4 weeks of isokinetic training with the right leg (T) whilst the left leg was untrained (UT), serving as a control. Each training session consisted of 10 x 10 maximal 90 degrees extension and flexion contractions at 180 degrees /s using a Kin-Com isokinetic dynamometer, with 1 min rest between bouts. Muscle biopsies were taken from the vastus lateralis immediately before and at the end of the supplementation period. Following freeze drying muscle fibres were dissected and characterised by their MHC profile, as type I, IIa, IIx, or as hybrids of these. Carnosine was measured by HPLC. There was a significant increase in carnosine in both T and UT legs of the beta-ALG (9.63 +/- 3.92 mmol kg(-1) dry muscle and 6.55 +/- 2.36 mmol kg(-1) dry muscle respectively). There was a significant increase in the carnosine content of all fibre phentotypes, with no significant difference between types. There were no significant differences in the changes in muscle or in fibres between the T and UT legs. In contrast there was no significant change in the carnosine content in either the T or UT legs with placebo. The results indicate that 4 weeks training has no effect on the muscle carnosine content. Whilst an increase was seen with beta-alanine supplementation, this was not further influenced by training. These findings suggest that beta-alanine availability is the main factor regulating muscle carnosine synthesis.

  6. Comparative assessment of knee extensor and flexor muscle strength measured using a hand-held vs. isokinetic dynamometer.

    PubMed

    Muff, Guillaume; Dufour, Stéphane; Meyer, Alain; Severac, François; Favret, Fabrice; Geny, Bernard; Lecocq, Jehan; Isner-Horobeti, Marie-Eve

    2016-09-01

    [Purpose] To compare measurements of knee extensor and flexor muscle strength performed using a hand-held dynamometer and an isokinetic dynamometer in apparently healthy subjects. [Subjects and Methods] Thirty adult volunteers underwent knee muscle strength evaluation using an isokinetic or a hand-held dynamometer. [Results] Strong positive correlations were found between the 2 methods, with correlation coefficients r ranging from 0.72 (95% confidence interval [CI], 0.48-0.86) to 0.87 (95% CI, 0.75-0.94), depending on the muscle group and the isokinetic evaluation mode. The reproducibility of the hand-held dynamometer findings was good, judged by a coefficient of variation of 3.2-4.2%. However, the correlation between the 2 methods for the assessment of flexor/extensor ratios ranged from -0.04 to 0.46. [Conclusion] Knee extensor and flexor muscle strength recorded with a hand-held dynamometer is reproducible and significantly correlated with the isokinetic values, indicating that this method may in some cases be a useful replacement for isokinetic strength measurement. However, for strength ratio assessment, and when judged against the isokinetic standard, a hand-held dynamometer is not a valid option.

  7. Comparative assessment of knee extensor and flexor muscle strength measured using a hand-held vs. isokinetic dynamometer

    PubMed Central

    Muff, Guillaume; Dufour, Stéphane; Meyer, Alain; Severac, François; Favret, Fabrice; Geny, Bernard; Lecocq, Jehan; Isner-Horobeti, Marie-Eve

    2016-01-01

    [Purpose] To compare measurements of knee extensor and flexor muscle strength performed using a hand-held dynamometer and an isokinetic dynamometer in apparently healthy subjects. [Subjects and Methods] Thirty adult volunteers underwent knee muscle strength evaluation using an isokinetic or a hand-held dynamometer. [Results] Strong positive correlations were found between the 2 methods, with correlation coefficients r ranging from 0.72 (95% confidence interval [CI], 0.48−0.86) to 0.87 (95% CI, 0.75−0.94), depending on the muscle group and the isokinetic evaluation mode. The reproducibility of the hand-held dynamometer findings was good, judged by a coefficient of variation of 3.2–4.2%. However, the correlation between the 2 methods for the assessment of flexor/extensor ratios ranged from −0.04 to 0.46. [Conclusion] Knee extensor and flexor muscle strength recorded with a hand-held dynamometer is reproducible and significantly correlated with the isokinetic values, indicating that this method may in some cases be a useful replacement for isokinetic strength measurement. However, for strength ratio assessment, and when judged against the isokinetic standard, a hand-held dynamometer is not a valid option. PMID:27799667

  8. Coefficient of variation in maximal and feigned static and dynamic grip efforts.

    PubMed

    Dvir, Z

    1999-01-01

    The purpose of this study was to investigate the validity of the coefficient of variation as an identifier of feigned grip effort. Seventeen healthy female aged 20 to 25 yr participated in the study. Maximal and feigned efforts were measured isometrically and isokinetically (concentric and eccentric) using the Jamar and KinCom dynamometers, respectively. Findings indicated that, in all situations, the coefficient of variation derived from the maximal effort was significantly (P < 0.0001) lower than that derived from the feigned effort. However, the extent of overlapping between the two was sufficiently large to render the test sensitivities very low. Consequently, regardless of the measurement method, the coefficient of variation is not a valid tool for identifying feigned grip effort in healthy subjects.

  9. Placebo effects of caffeine on maximal voluntary concentric force of the knee flexors and extensors.

    PubMed

    Tallis, Jason; Muhammad, Bilal; Islam, Mohammed; Duncan, Michael J

    2016-09-01

    We examined the placebo effect of caffeine and the combined effect of caffeine and caffeine expectancy on maximal voluntary strength. Fourteen men completed 4 randomized, single-blind experimental trials: (1) told caffeine, given caffeine (5 mg/kg) (CC); (2) told caffeine, given placebo (CP); (3) told placebo, given placebo (PP); and (4) told placebo, given caffeine (PC). Maximal voluntary concentric force and fatigue resistance of the knee flexors and extensors were measured using isokinetic dynamometry. A significant and equal improvement in peak concentric force was found in the CC and PC trials. Despite participants believing caffeine would evoke a performance benefit, there was no effect of CP. Caffeine caused an improvement in some aspects of muscle strength, but there was no additional effect of expectancy. Performance was poorer in participants who believed caffeine would have the greatest benefit, which highlights a link between expected ergogenicity, motivation, and personality characteristics. Muscle Nerve 54: 479-486, 2016. © 2015 Wiley Periodicals, Inc.

  10. Effects of isokinetic training on the rate of movement during ambulation in hemiparetic patients.

    PubMed

    Glasser, L

    1986-05-01

    The purpose of this study was to determine the effects of isokinetic training on the rate of movement during ambulation in hemiparetic patients. Ten male and 10 female subjects, aged 40 to 75 years, participated in the study. The 20 hemiparetic subjects were assigned randomly to either a control group or an experimental group. All of the subjects participated in a conventional therapeutic exercise program and gait training. The experimental group also received isokinetic training on the Kinetron exercise machine as part of their program. Functional ambulation profile tests were administered to each subject before and after the five-week experimental period. All of the subjects showed improvement in the rate of ambulation and in overall ambulation performance. The differences in ambulation times and functional ambulation profile scores between the two groups were shown to be insignificant.

  11. [Non-typical measurements during a isokinetic training session after ACL-reconstruction].

    PubMed

    Baumeister, J; Weiss, M

    2002-06-01

    Rehabilitative resistance work programs after ACL-injuries are derived from programs known from competitive sports training. The development of different parameters (max. Power output, total work per set) was examined in 12 patients after ACL-reconstruction during a training session on an isokinetic training machine with a velocity of 120 degrees /sec and 60 degrees /sec. The results let suppose that neuromuscular structures of patients with ACL-reconstruction react different to those of healthy people in the control group. Therefore the rehabilitation programs have to be adjusted to the recruitment pattern of motor units after ACL-injury. In this case there has to be a progression of intensity during the isokinetic training session.

  12. Effects of axis placement on measurement of isokinetic flexion and extension torque in the lumbar spine.

    PubMed

    Stokes, I A; Gookin, D M; Reid, S; Hazard, R G

    1990-06-01

    We wanted to ascertain whether changing the machine axis placement relative to the anatomic landmarks of a tested subject in isokinetic flexion and extension trunk strength would influence the measurements obtained. Twenty healthy volunteers were tested with the machine axis intentionally displaced from a reference position at the lumbosacral junction. Displacing the axis 50 mm vertically produced on average 15% increase in the torque produced, and displacing it 10 mm horizontally produced approximately 5% reduction in torque, independent of the direction of displacement from the reference position. The angle at which maximum torque occurred and the ratio of extension to flexion torque were unaffected by axis placement. Intertester reliability in axis placement was found experimentally to produce variations of usually less than 10 mm. We conclude that isokinetic trunk strength measurement is affected by testing axis placement; this should be controlled, especially in repetitive testing of the same individual.

  13. Isokinetic knee muscle strength of individuals with mental retardation, a comparative study.

    PubMed

    Angelopoulou, N; Tsimaras, V; Christoulas, K; Kokaridas, D; Mandroukas, K

    1999-06-01

    The purpose of this study was to assess differences in isokinetic muscle torque in the knee among mentally retarded individuals with Down syndrome, mentally retarded individuals without Down syndrome, and sedentary subjects without mental retardation (ns of 7, 8, and 12, respectively). Subjects performed strength tests to knee extension and flexion on a Cybex II isokinetic dynamometer. The measure was peak torque at angular velocities of 60, 120, and 300 degrees/sec. For the Mentally Retarded subjects with and without Down syndrome, the test was performed on two separate days 24 hr. apart. For Sedentary subjects, testing was performed on one day. Their scores indicated significantly higher values of torque than the two other groups. Also, subjects with Down syndrome had inferior muscle torque of lower extremities than peers in the Mentally Retarded Group.

  14. Higher hamstring-to-quadriceps isokinetic strength ratio during the first post-operative months in patients with quadriceps tendon compared to hamstring tendon graft following ACL reconstruction.

    PubMed

    Fischer, Felix; Fink, Christian; Herbst, Elmar; Hoser, Christian; Hepperger, Caroline; Blank, Cornelia; Gföller, Peter

    2017-03-21

    The aim of this study was to compare isokinetic quadriceps and hamstring muscle strength in patients following anterior cruciate ligament (ACL) reconstruction who received either hamstring (HT) or quadriceps (QT) tendon autografts at two time intervals within the first year after surgery. One hundred twenty-four patients, 81 males (age 22.0 ± 6.2 years) and 43 females (age 20.9 ± 8.7 years), participated in this study. ACL reconstruction was performed with either quadriceps tendon autografts (QT; n = 61) or hamstring tendon autografts (HT; n = 63). Two isokinetic muscle strength tests (t1: 5.5 ± 1.2 months; t2: 7.6 ± 1.6 months) were performed at an angular velocity of 60°/s in both the injured and contralateral knees. An independent t test as well as a two-factor analysis of variance with repeated measurements was used. The significance level was set at p < 0.05. A statistically significant lower knee extensor strength was observed in the QT group within one year after surgery (p < 0.001). Additionally, data showed a significant higher H/Q ratio in QT patients compared to the HT group at t1 (p < 0.001) and t2 (p = 0.001) as well as a significant effect over time (p < 0.001) and interaction effect of time and graft (p = 0.007). Side-to-side values for extensor muscle strength were significantly (p < 0.001) greater in HT graft patients, while QT patients showed significantly (p < 0.001) greater values for flexor muscle strength at both time points of isokinetic testing, respectively. The results of this study indicate that graft choice has an impact on extensor strength in the first months after ACL reconstruction; however, there is no impact on flexor strength. The finding of a higher H/Q ratio in patients with QT grafts within the first months following surgery is possibly of clinical relevance. This may potentially be associated with lower stress on the maturing ACL graft. Furthermore, normal thigh strength can be restored

  15. Isokinetic strength testing does not predict hamstring injury in Australian Rules footballers.

    PubMed

    Bennell, K; Wajswelner, H; Lew, P; Schall-Riaucour, A; Leslie, S; Plant, D; Cirone, J

    1998-12-01

    To determine the relation of hamstring and quadriceps muscle strength and imbalance to hamstring injury using a prospective observational cohort study A total of 102 senior male Australian Rules footballers aged 22.2 (3.6) years were tested at the start of a football season. Maximum voluntary concentric and eccentric torque of the hamstring and quadriceps muscles of both legs was assessed using a Kin-Com isokinetic dynamometer at angular velocities of 60 and 180 degrees/second. Twelve (11.8%) players sustained clinically diagnosed hamstring strains which caused them to miss one or more matches over the ensuing season. There were no significant differences for any of the isokinetic variables comparing the injured and non-injured legs in players with unilateral hamstring strains (n=9). Neither the injured nor the non-injured leg of injured players differed from the mean of left and right legs in non-injured players for any isokinetic variable. The hamstring to opposite hamstring ratios also did not differ between injured and non-injured players. A hamstring to opposite hamstring ratio of less than 0.90 and a hamstring to quadriceps ratio of less than 0.60 were not associated with an increased risk of hamstring injury. A significantly greater percentage of players who sustained a hamstring strain reported a history of hamstring strain compared with non-injured players (p=0.02). However, this was not related to muscle weakness or imbalance. Isokinetic muscle strength testing was not able to directly discriminate Australian Rules football players at risk for a hamstring injury.

  16. Isokinetic Strength Changes Following Long-Duration Spaceflight on the ISS.

    PubMed

    English, Kirk L; Lee, Stuart M C; Loehr, James A; Ploutz-Snyder, Robert J; Ploutz-Snyder, Lori L

    2015-12-01

    Long-duration spaceflight results in a loss of muscle strength that poses both operational and medical risks, particularly during emergency egress, upon return to Earth, and during future extraterrestrial exploration. Isokinetic testing of the knee, ankle, and trunk quantifies movement-specific strength changes following spaceflight and offers insight into the effectiveness of in-flight exercise countermeasures. We retrospectively evaluated changes in isokinetic strength for 37 ISS crewmembers (Expeditions 1-25) following 163 ± 38 d (mean ± SD) of spaceflight. Gender, in-flight resistance exercise hardware, and preflight strength were examined as potential modifiers of spaceflight-induced strength changes. Mean isokinetic strength declined 8-17% following spaceflight. One month after return to Earth, strength had improved, but small deficits of 1-9% persisted. Spaceflight-induced strength losses were not different between men and women. Mean strength losses were as much as 7% less in crewmembers who flew after the Advanced Resistive Exercise Device (ARED) replaced the interim Resistive Exercise Device (iRED) as the primary in-flight resistance exercise hardware, although these differences were not statistically significant. Absolute and relative preflight strength were moderately correlated (r = -0.47 and -0.54, respectively) with postflight strength changes. In-flight resistance exercise did not prevent decreased isokinetic strength after long-duration spaceflight. However, continued utilization of ARED, a more robust resistance exercise device providing higher loads than iRED, may result in greater benefits as exercise prescriptions are optimized. With reconditioning upon return to Earth, strength is largely recovered within 30 d.

  17. Lower-extremity isokinetic strength profiling in professional rugby league and rugby union.

    PubMed

    Brown, Scott R; Brughelli, Matt; Griffiths, Peter C; Cronin, John B

    2014-03-01

    While several studies have documented isokinetic knee strength in junior and senior rugby league players, investigations of isokinetic knee and hip strength in professional rugby union players are limited. The purpose of this study was to provide lower-extremity strength profiles and compare isokinetic knee and hip strength of professional rugby league and rugby union players. 32 professional rugby league and 25 professional rugby union players. Cross-sectional analysis. Isokinetic dynamometry was used to evaluate peak torque and strength ratios of the dominant and nondominant legs during seated knee-extension/ flexion and supine hip-extension/flexion actions at 60°/s. Forwards from both codes were taller and heavier and had a higher body-mass index than the backs of each code. Rugby union forwards produced significantly (P < .05) greater peak torque during knee flexion in the dominant and nondominant legs (ES = 1.81 and 2.02) compared with rugby league forwards. Rugby league backs produced significantly greater hip-extension peak torque in the dominant and nondominant legs (ES = 0.83 and 0.77) compared with rugby union backs. There were no significant differences in hamstring-to-quadriceps ratios between code, position, or leg. Rugby union forwards and backs produced significantly greater knee-flexion-to-hip-extension ratios in the dominant and nondominant legs (ES = 1.49-2.26) than rugby union players. It seems that the joint torque profiles of players from rugby league and union codes differ, which may be attributed to the different demands of each code.

  18. Algorithms and novel applications based on the isokinetic ensemble. II. Ab initio molecular dynamics

    NASA Astrophysics Data System (ADS)

    Minary, Peter; Martyna, Glenn J.; Tuckerman, Mark E.

    2003-02-01

    In this paper (Paper II), the isokinetic dynamics scheme described in Paper I is combined with the plane-wave based Car-Parrinello (CP) ab initio molecular dynamics (MD) method [R. Car and M. Parrinello, Phys. Rev. Lett. 55, 2471 (1985)] to enable the efficient study of chemical reactions and metallic systems. The Car-Parrinello approach employs "on the fly" electronic structure calculations as a means of generating accurate internuclear forces for use in a molecular dynamics simulation. This is accomplished by the introduction of an extended Lagrangian that contains the electronic orbitals as fictitious dynamical variables (often expressed directly in terms of the expansion coefficients of the orbitals in a particular basis set). Thus, rather than quench the expansion coefficients to obtain the ground state energy and nuclear forces at every time step, the orbitals are "propagated" under conditions that allow them to fluctuate rapidly around their global minimum and, hence, generate an accurate approximation to the nuclear forces as the simulation proceeds. Indeed, the CP technique requires the dynamics of the orbitals to be both fast compared to the nuclear degrees of freedom while keeping the fictitious kinetic energy that allows them to be propagated dynamically as small as possible. While these conditions can be easy to achieve in many types of systems, in metals and highly exothermic chemical reactions difficulties arise. (Note, the CP dynamics of metals is incorrect because the nuclear motion does not occur on the ground state electronic surface but it can, nonetheless, provide useful information.) In order to alleviate these difficulties the isokinetic methods of Paper I are applied to derive isokinetic CP equations of motion. The efficacy of the new isokinetic CPMD method is demonstrated on model and realistic systems. The latter include, metallic systems, liquid aluminum, a small silicon sample, the 2×1 reconstruction of the silicon 100 surface, and the

  19. Association with isokinetic ankle strength measurements and normal clinical muscle testing in sciatica patients.

    PubMed

    Ustun, N; Erol, O; Ozcakar, L; Ceceli, E; Ciner, O Akar; Yorgancioglu, Z R

    2013-01-01

    Sensitive muscle strength tests are needed to measure muscle strength in the diagnosis and management of sciatica patients. The aim of this study was to assess the isokinetic muscle strength in sciatica patients' and control subjects' ankles that exhibited normal ankle muscle strength when measured clinically. Forty-six patients with L5 and/or S1 nerve compression, and whose age, sex, weight, and height matched 36 healthy volunteers, were recruited to the study. Heel-walking, toe-walking, and manual muscle testing were used to perform ankle dorsiflexion and plantar flexion strengths in clinical examination. Patients with normal ankle dorsiflexion and plantar flexion strengths assessed by manual muscle testing and heel-and toe-walking tests were included in the study. Bilateral isokinetic (concentric/concentric) ankle plantar-flexion-dorsiflexion measurements of the patients and controls were performed within the protocol of 30°/sec (5 repetitions). Peak torque and peak torque/body weight were obtained for each ankle motion of the involved limb at 30°/s speed. L5 and/or S1 nerve compression was evident in 46 patients (76 injured limbs). Mean disease duration was two years. The plantar flexion muscle strength of the patients was found to be lower than that of the controls (p=0.036). The dorsiflexion muscle strength of the patients was found to be the same as that of the controls (p=0.211). Isokinetic testing is superior to clinical muscle testing when evaluating ankle plantar flexion torque in sciatica patients. Therefore, isokinetic muscle testing may be helpful when deciding whether to place a patient into a focused rehabilitation program.

  20. The effects of creatine supplementation on thermoregulation and isokinetic muscular performance following acute (3-day) supplementation.

    PubMed

    Rosene, J M; Matthews, T D; Mcbride, K J; Galla, A; Haun, M; Mcdonald, K; Gagne, N; Lea, J; Kasen, J; Farias, C

    2015-12-01

    The purpose of this investigation was to determine the effects of 3 d of creatine supplementation on thermoregulation and isokinetic muscular performance. Fourteen males performed two exercise bouts following 3 d of creatine supplementation and placebo. Subjects exercised for 60 min at 60-65% of VO2max in the heat followed by isokinetic muscular performance at 60, 180, and 300°·s(-1). Dependent variables for pre- and postexercise included nude body weight, urine specific gravity, and serum creatinine levels. Total body water, extracellular water and intracellular water were measured pre-exercise. Core temperature was assessed every 5 min during exercise. Peak torque and Fatigue Index were used to assess isokinetic muscular performance. Core temperature increased during the run for both conditions. Total body water and extracellular water were significantly greater (P<0.05) following creatine supplementation. No significant difference (P>0.05) was found between conditions for intracellular water, nude body weight, urine specific gravity, and serum creatinine. Pre-exercise scores for urine specific gravity and serum creatinine were significantly less (P<0.05) versus post-exercise. No significant differences (P>0.05) were found in peak torque values or Fatigue Index between conditions for each velocity. A significant (P<0.05) overall velocity effect was found for both flexion and extension. As velocity increased, mean peak torque values decreased. Three d of creatine supplementation does not affect thermoregulation during submaximal exercise in the heat and is not enough to elicit an ergogenic effect for isokinetic muscle performance following endurance activity.

  1. Isokinetic analysis of ankle and ground reaction forces in runners and triathletes

    PubMed Central

    Luna, Natália Mariana Silva; Alonso, Angelica Castilho; Brech, Guilherme Carlos; Mochizuki, Luis; Nakano, Eduardo Yoshio; Greve, Júlia Maria D'Andréa

    2012-01-01

    OBJECTIVE: To analyze and compare the vertical component of ground reaction forces and isokinetic muscle parameters for plantar flexion and dorsiflexion of the ankle between long-distance runners, triathletes, and non-athletes. METHODS: Seventy-five males with a mean age of 30.26 (±6.5) years were divided into three groups: a triathlete group (n = 26), a long-distance runner group (n = 23), and a non-athlete control group. The kinetic parameters were measured during running using a force platform, and the isokinetic parameters were measured using an isokinetic dynamometer. RESULTS: The non-athlete control group and the triathlete group exhibited smaller vertical forces, a greater ground contact time, and a greater application of force during maximum vertical acceleration than the long-distance runner group. The total work (180°/s) was greater in eccentric dorsiflexion and concentric plantar flexion for the non-athlete control group and the triathlete group than the long-distance runner group. The peak torque (60°/s) was greater in eccentric plantar flexion and concentric dorsiflexion for the control group than the athlete groups. CONCLUSIONS: The athlete groups exhibited less muscle strength and resistance than the control group, and the triathletes exhibited less impact and better endurance performance than the runners. PMID:23018298

  2. Comparison of knee laxity and isokinetic muscle strength in patients with a posterior cruciate ligament injury

    PubMed Central

    Jeon, Kyoungkyu

    2016-01-01

    [Purpose] The aim of this study was to compare knee laxity and isokinetic muscle strength in patients with an isolated posterior cruciate ligament injury. [Subjects and Methods] Twenty high school rugby players with a previous posterior cruciate ligament injury and abnormal findings higher than surgical grade I were included. Laxity with 132 N of pressure was measured using Kneelax 3 to assess the stability of the posterior cruciate ligament, and flexor and extensor torques were measured at 60°/sec, 180°/sec, and 240°/sec to measure the isokinetic muscle strength of the knee joint. The average and standard deviation values were extracted from all data to assess the measured data. [Results] Regarding the ipsilateral and contralateral laxity, the deviation value at the peak force and maximum manual drawer was statistically significant. The peak torque and peak torque per body weight in isokinetic measurements were significantly different only for knee extensor torque at 60°/sec, 180°/sec, and 240°/sec. [Conclusion] Return to normal activities post injury is important. Thus base data gathered by comparing patients’ ipsilateral and contralateral sides will serve as essential criteria for structuring future rehabilitation programs to facilitate functional improvements. PMID:27134367

  3. Isokinetic Strength Responses to Season-long Training and Competition in Turkish Elite Soccer Players

    PubMed Central

    Eniseler, Niyazi; Şahan, Çağatay; Vurgun, Hikmet; Mavi, Hasan Fehmi

    2012-01-01

    There are not enough studies that describe the isokinetic strength of professional soccer players at high angular velocities. The purpose of this study was to evaluate the seasonal changes in isokinetic strength of Turkish professional soccer players (n=14) over the course of a 24-week soccer season. The isokinetic strength of players who underwent usual soccer training and weekly competition throughout the soccer season was assessed by means of the Biodex System 3 dynamometer with the knee attachment. The peak torque of knee extensor and flexor muscles were measured at angular velocities of 60°/s, 300°/s and 500°/s. Players were tested at the beginning and end of the competitive season. While the first- and second-test measurements did not show significant changes at 60°/s and 300°/s angular velocities, at the end of the training period, players’ knee strength changed significantly at 500°/s angular velocities. In addition, the H/Q ratio improved significantly for the dominant as well as non-dominant leg at 500°/s. Significant bilateral strength improvements for knee flexors were also observed at 500°/s. The findings of this study suggest that usual daily soccer training (technical, tactical, power, strength, endurance, flexibility, etc.) and weekly competition might produce changes in knee strength at high angular velocities. PMID:23487507

  4. Neuromuscular and muscle-tendon system adaptations to isotonic and isokinetic eccentric exercise.

    PubMed

    Guilhem, G; Cornu, C; Guével, A

    2010-06-01

    To present the properties of an eccentric contraction and compare neuromuscular and muscle-tendon system adaptations induced by isotonic and isokinetic eccentric trainings. An eccentric muscle contraction is characterized by the production of muscle force associated to a lengthening of the muscle-tendon system. This muscle solicitation can cause micro lesions followed by a regeneration process of the muscle-tendon system. Eccentric exercise is commonly used in functional rehabilitation for its positive effect on collagen synthesis but also for resistance training to increase muscle strength and muscle mass in athletes. Indeed, eccentric training stimulates muscle hypertrophy, increases the fascicle pennation angle, fascicles length and neural activation, thus inducing greater strength gains than concentric or isometric training programs. Eccentric exercise is commonly performed either against a constant external load (isotonic) or at constant velocity (isokinetic), inducing different mechanical constraints. These different mechanical constraints could induce structural and neural adaptive strategies specific to each type of exercise. The literature tends to show that isotonic mode leads to a greater strength gain than isokinetic mode. This observation could be explained by a greater neuromuscular activation after IT training. However, the specific muscle adaptations induced by each mode remain difficult to determine due to the lack of standardized, comparative studies. 2010 Elsevier Masson SAS. All rights reserved.

  5. Effect of unilateral exercise on spinal and pelvic deformities, and isokinetic trunk muscle strength.

    PubMed

    Jeon, Kyoungkyu; Kim, Soonyoung

    2016-03-01

    [Purpose] The purpose of this study was to collect basic data regarding the prevention of spinal and pelvic deformities by investigating the spinal shape and muscular function characteristics of imbalance reduction and functional improvement following asymmetric activities. [Subjects and Methods] The subjects were 14 archery athletes who mostly perform unilateral motion with spinal and pelvic pain, and 19 healthy subjects. All the participants were evaluated using spinal structure analysis and for 60°/sec isokinetic muscular strength of the trunk. [Results] Between the two groups, there were significant differences in the interaction effect of trunk inclination deformities, and flexor and extensor 60°/sec isokinetic muscular strength of the trunk. Also, the main effects of gender comparison showed significant differences in the trunk inclination deformities, pelvic rotation deformities, lordosis angles, and flexor and extensor 60 ˚/sec isokinetic muscular strengths of the trunk. [Conclusion] The basic data obtained in this study can be used to help develop a strategic exercise program for improving unilateral movement and malalignment of the spine and pelvis.

  6. Effect of unilateral exercise on spinal and pelvic deformities, and isokinetic trunk muscle strength

    PubMed Central

    Jeon, Kyoungkyu; Kim, Soonyoung

    2016-01-01

    [Purpose] The purpose of this study was to collect basic data regarding the prevention of spinal and pelvic deformities by investigating the spinal shape and muscular function characteristics of imbalance reduction and functional improvement following asymmetric activities. [Subjects and Methods] The subjects were 14 archery athletes who mostly perform unilateral motion with spinal and pelvic pain, and 19 healthy subjects. All the participants were evaluated using spinal structure analysis and for 60°/sec isokinetic muscular strength of the trunk. [Results] Between the two groups, there were significant differences in the interaction effect of trunk inclination deformities, and flexor and extensor 60°/sec isokinetic muscular strength of the trunk. Also, the main effects of gender comparison showed significant differences in the trunk inclination deformities, pelvic rotation deformities, lordosis angles, and flexor and extensor 60 ˚/sec isokinetic muscular strengths of the trunk. [Conclusion] The basic data obtained in this study can be used to help develop a strategic exercise program for improving unilateral movement and malalignment of the spine and pelvis. PMID:27134369

  7. Results and Conclusions from the NASA Isokinetic Total Water Content Probe 2009 IRT Test

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew; Brinker, David

    2010-01-01

    The NASA Glenn Research Center has developed and tested a Total Water Content Isokinetic Sampling Probe. Since, by its nature, it is not sensitive to cloud water particle phase nor size, it is particularly attractive to support super-cooled large droplet and high ice water content aircraft icing studies. The instrument comprises the Sampling Probe, Sample Flow Control, and Water Vapor Measurement subsystems. Results and conclusions are presented from probe tests in the NASA Glenn Icing Research Tunnel (IRT) during January and February 2009. The use of reference probe heat and the control of air pressure in the water vapor measurement subsystem are discussed. Several run-time error sources were found to produce identifiable signatures that are presented and discussed. Some of the differences between measured Isokinetic Total Water Content Probe and IRT calibration seems to be caused by tunnel humidification and moisture/ice crystal blow around. Droplet size, airspeed, and liquid water content effects also appear to be present in the IRT calibration. Based upon test results, the authors provide recommendations for future Isokinetic Total Water Content Probe development.

  8. Isokinetic analysis of ankle and ground reaction forces in runners and triathletes.

    PubMed

    Luna, Natália Mariana Silva; Alonso, Angelica Castilho; Brech, Guilherme Carlos; Mochizuki, Luis; Nakano, Eduardo Yoshio; Greve, Júlia Maria D'Andrea

    2012-09-01

    To analyze and compare the vertical component of ground reaction forces and isokinetic muscle parameters for plantar flexion and dorsiflexion of the ankle between long-distance runners, triathletes, and nonathletes. Seventy-five males with a mean age of 30.26 (±6.5) years were divided into three groups: a triathlete group (n=26), a long-distance runner group (n = 23), and a non-athlete control group. The kinetic parameters were measured during running using a force platform, and the isokinetic parameters were measured using an isokinetic dynamometer. The non-athlete control group and the triathlete group exhibited smaller vertical forces, a greater ground contact time, and a greater application of force during maximum vertical acceleration than the long-distance runner group. The total work (180º/s) was greater in eccentric dorsiflexion and concentric plantar flexion for the non-athlete control group and the triathlete group than the long-distance runner group. The peak torque (60º/s) was greater in eccentric plantar flexion and concentric dorsiflexion for the control group than the athlete groups. The athlete groups exhibited less muscle strength and resistance than the control group, and the triathletes exhibited less impact and better endurance performance than the runners.

  9. Comparison of knee laxity and isokinetic muscle strength in patients with a posterior cruciate ligament injury.

    PubMed

    Jeon, Kyoungkyu

    2016-03-01

    [Purpose] The aim of this study was to compare knee laxity and isokinetic muscle strength in patients with an isolated posterior cruciate ligament injury. [Subjects and Methods] Twenty high school rugby players with a previous posterior cruciate ligament injury and abnormal findings higher than surgical grade I were included. Laxity with 132 N of pressure was measured using Kneelax 3 to assess the stability of the posterior cruciate ligament, and flexor and extensor torques were measured at 60°/sec, 180°/sec, and 240°/sec to measure the isokinetic muscle strength of the knee joint. The average and standard deviation values were extracted from all data to assess the measured data. [Results] Regarding the ipsilateral and contralateral laxity, the deviation value at the peak force and maximum manual drawer was statistically significant. The peak torque and peak torque per body weight in isokinetic measurements were significantly different only for knee extensor torque at 60°/sec, 180°/sec, and 240°/sec. [Conclusion] Return to normal activities post injury is important. Thus base data gathered by comparing patients' ipsilateral and contralateral sides will serve as essential criteria for structuring future rehabilitation programs to facilitate functional improvements.

  10. Reliability of rate of velocity development and phase measures on an isokinetic device.

    PubMed

    Brown, Lee E; Whitehurst, Michael; Findley, Brian W

    2005-02-01

    Isokinetic dynamometers have been measured for torque and force reliability in the past, but little research has been performed on rate of velocity development (RVD) measures. The purpose of this study was to determine the reliability of RVD measures on an isokinetic device at slow and fast speeds. Twenty volunteers performed 5 repetitions of concentric knee extension at 1.04 and 4.18 rad.s(-1) on a Kin-Com isokinetic dynamometer. Each subject was identically posttested 7 days later. Data were separated into 3 velocity range-of-motion (ROM) phases of RVD, load range (LR), and deceleration (DCCROM). Analyses of variance (ANOVAs) were performed to analyze the mean data between day 1 and day 2, while intraclass correlation coefficients (ICCs) were performed for reliability. Results at 1.04 rad.s(-1) demonstrated a low but significant (p < 0.05) ICC value (0.58) only for LR, while at 4.18 rad.s(-1) RVD (0.87), LR (0.83), and DCC (0.55) all exhibited significant ICC values. Percent error for high-speed testing ranged from 1.4-3.19%. No variable exhibited a significant mean difference between testing days. These results collectively point to moderate to high phase reliability for RVD measures at fast speeds of testing, while the slow speed showed very low reliability. Therefore, care should be exercised at slow speeds when comparing RVD measures from test to test.

  11. Isokinetic assessment of knee flexor/extensor muscular strength in elderly women.

    PubMed

    Aquino, Marcos de Amorim; Leme, Luiz Eugênio Garcez; Amatuzzi, Marco Martins; Greve, Júlia Maria D'Andréa; Terreri, Antônio Sérgio A P; Andrusaitis, Félix Ricardo; Nardelli, Júlio César de Carvalho

    2002-01-01

    To assess knee flexor-extensor muscular strength in elderly women with no previous history of musculoskeletal disorders on the lower limbs using an isokinetic dynamometer, in order to obtain data that could be used as a comparative parameter in the evaluation of elderly women with knee disorders, thus facilitating a better rehabilitation of these patients. Twenty-six volunteers aged 75 to 83 years were studied using a Cybex 6000 isokinetic dynamometer. The chosen angular velocity was 60 degrees /s, and concentric exercise was used for either flexion or extension. The studied parameters were: peak torque, angle of peak torque, and flexor-extensor torque rate. There were no differences between dominant (D) and nondominant (ND) knee peak torque values. This was true for both flexor (D = 42.46 +/- 9.09 Nm / ND = 40.65 +/- 9.38 Nm) and extensor (D = 76.92 +/- 13.97 Nm / ND = 77.65 +/- 15.21 Nm) movements. The descriptive statistical analysis of the values obtained for the flexor-extensor peak torque rate and for the angle of occurrence of peak torque was the same for the dominant and nondominant sides. The values of peak torque for the contralateral side can be used as a reference during rehabilitation of elderly women with acute disease of the knee, and the angular velocity of 60 degrees /s is proper and safe for isokinetic assessment of elderly people.

  12. Angular Velocity Affects Trunk Muscle Strength and EMG Activation during Isokinetic Axial Rotation

    PubMed Central

    Fan, Jian-Zhong; Liu, Xia; Ni, Guo-Xin

    2014-01-01

    Objective. To evaluate trunk muscle strength and EMG activation during isokinetic axial rotation at different angular velocities. Method. Twenty-four healthy young men performed isokinetic axial rotation in right and left directions at 30, 60, and 120 degrees per second angular velocity. Simultaneously, surface EMG was recorded on external oblique (EO), internal oblique (IO), and latissimus dorsi (LD) bilaterally. Results. In each direction, with the increase of angular velocity, peak torque decreased, whereas peak power increased. During isokinetic axial rotation, contralateral EO as well as ipsilateral IO and LD acted as primary agonists, whereas, ipsilateral EO as well as contralateral IO and LD acted as primary antagonistic muscles. For each primary agonist, the root mean square values decreased with the increase of angular velocity. Antagonist coactiviation was observed at each velocity; however, it appears to be higher with the increase of angular velocity. Conclusion. Our results suggest that velocity of rotation has great impact on the axial rotation torque and EMG activity. An inverse relationship of angular velocity was suggested with the axial rotation torque as well as root mean square value of individual trunk muscle. In addition, higher velocity is associated with higher coactivation of antagonist, leading to a decrease in torque with the increase of velocity. PMID:24804227

  13. The isokinetic rotator cuff strength ratios in overhead athletes: Assessment and exercise effect.

    PubMed

    Berckmans, Kelly; Maenhout, Annelies G; Matthijs, Lien; Pieters, Louise; Castelein, Birgit; Cools, Ann M

    2017-09-01

    Muscle strength imbalance in the shoulder region can be considered as a predisposing factor in the development of movement dysfunctions, possibly leading to overuse injuries. Repetitive overhead throwing, performed in sports, may result in muscle imbalance between the external (ER) and internal (IR) rotators. Muscle strength measured with an isokinetic device, is reported as a concentric (CON) or eccentric (ECC) force. The balance between an agonist and an antagonist is mentioned as a ratio (CON/CON or ECC/CON). The aim of this systematic literature review is to provide an overview of the existing evidence considering the isokinetic muscle strength ratios of ER and IR of the shoulder in healthy overhead athletes. In addition, the effect of exercise programs on these ratios was investigated. Two online databases (Web of Science and PubMed) were consulted using different search strategies. Articles were selected based on inclusion and exclusion criteria. All included articles were assessed on their methodological quality. There is moderate evidence for a lower functional deceleration ratio (ECC ER/CON IR) at the dominant side. This lower ratio is due to a large overweight of CON IR strength on that side. There is no consensus about which exercise program is the most effective in altering the shoulder isokinetic strength ratios. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2016-08-01

    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. 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. 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). It seems that long-term T2DM cause some neuromuscular adaptations to maintain knee flexor muscle performance during functional activity especially postural control.

  15. Maximally Expressive Modeling

    NASA Technical Reports Server (NTRS)

    Jaap, John; Davis, Elizabeth; Richardson, Lea

    2004-01-01

    Planning and scheduling systems organize tasks into a timeline or schedule. Tasks are logically grouped into containers called models. Models are a collection of related tasks, along with their dependencies and requirements, that when met will produce the desired result. One challenging domain for a planning and scheduling system is the operation of on-board experiments for the International Space Station. In these experiments, the equipment used is among the most complex hardware ever developed; the information sought is at the cutting edge of scientific endeavor; and the procedures are intricate and exacting. Scheduling is made more difficult by a scarcity of station resources. The models to be fed into the scheduler must describe both the complexity of the experiments and procedures (to ensure a valid schedule) and the flexibilities of the procedures and the equipment (to effectively utilize available resources). Clearly, scheduling International Space Station experiment operations calls for a maximally expressive modeling schema.

  16. Maximally natural supersymmetry.

    PubMed

    Dimopoulos, Savas; Howe, Kiel; March-Russell, John

    2014-09-12

    We consider 4D weak scale theories arising from 5D supersymmetric (SUSY) theories with maximal Scherk-Schwarz breaking at a Kaluza-Klein scale of several TeV. Many of the problems of conventional SUSY are avoided. Apart from 3rd family sfermions the SUSY spectrum is heavy, with only ∼50% tuning at a gluino mass of ∼2  TeV and a stop mass of ∼650  GeV. A single Higgs doublet acquires a vacuum expectation value, so the physical Higgs boson is automatically standard-model-like. A new U(1)^{'} interaction raises m_{h} to 126 GeV. For minimal tuning the associated Z^{'}, as well as the 3rd family sfermions, must be accessible to LHC13. A gravitational wave signal consistent with hints from BICEP2 is possible if inflation occurs when the extra dimensions are small.

  17. Effect of caffeine ingestion on maximal voluntary contraction strength in upper- and lower-body muscle groups.

    PubMed

    Timmins, Tomas D; Saunders, David H

    2014-11-01

    The effect of caffeine on strength-power performance is equivocal, especially with regard to maximal voluntary contraction (MVC) strength. This is partly related to differences in upper- and lower-body musculature. However, there is no evidence to suggest whether this is a product of muscle group location, muscle group size, or both. Consequently, the primary aim of this study was to establish whether the effect of caffeine ingestion on MVC strength in upper- and lower-body muscle groups is significantly different, and if so, to determine whether this is a product of muscle group size. In a randomized, subject-blind crossover manner, 16 resistance-trained men (estimated caffeine intake [mean ± SD] 95.4 ± 80.0 mg·d) received either 6 mg·kg of caffeine (CAF) or a placebo (PLA). Isokinetic peak torque of the knee extensors, ankle plantar flexors, elbow flexors and wrist flexors were measured at an angular velocity of 60°·s. Statistical analyses revealed a significant increase in isokinetic peak torque from PLA to CAF (p = 0.011) and a significant difference in isokinetic peak torque between muscle groups (p < 0.001). However, there was no significant treatment × muscle group interaction (p = 0.056). Nonetheless, the %improvement in isokinetic peak torque with caffeine increased with muscle group size. In conclusion, a moderate dose of caffeine improves MVC strength in resistance-trained men regardless of muscle group location, whereas the influence of muscle group size remains uncertain. This research may be useful for competitive and recreational athletes aiming to increase strength-power performance.

  18. Maximally Expressive Task Modeling

    NASA Technical Reports Server (NTRS)

    Japp, John; Davis, Elizabeth; Maxwell, Theresa G. (Technical Monitor)

    2002-01-01

    Planning and scheduling systems organize "tasks" into a timeline or schedule. The tasks are defined within the scheduling system in logical containers called models. The dictionary might define a model of this type as "a system of things and relations satisfying a set of rules that, when applied to the things and relations, produce certainty about the tasks that are being modeled." One challenging domain for a planning and scheduling system is the operation of on-board experiment activities for the Space Station. The equipment used in these experiments is some of the most complex hardware ever developed by mankind, the information sought by these experiments is at the cutting edge of scientific endeavor, and the procedures for executing the experiments are intricate and exacting. Scheduling is made more difficult by a scarcity of space station resources. The models to be fed into the scheduler must describe both the complexity of the experiments and procedures (to ensure a valid schedule) and the flexibilities of the procedures and the equipment (to effectively utilize available resources). Clearly, scheduling space station experiment operations calls for a "maximally expressive" modeling schema. Modeling even the simplest of activities cannot be automated; no sensor can be attached to a piece of equipment that can discern how to use that piece of equipment; no camera can quantify how to operate a piece of equipment. Modeling is a human enterprise-both an art and a science. The modeling schema should allow the models to flow from the keyboard of the user as easily as works of literature flowed from the pen of Shakespeare. The Ground Systems Department at the Marshall Space Flight Center has embarked on an effort to develop a new scheduling engine that is highlighted by a maximally expressive modeling schema. This schema, presented in this paper, is a synergy of technological advances and domain-specific innovations.

  19. Maximally Expressive Task Modeling

    NASA Technical Reports Server (NTRS)

    Japp, John; Davis, Elizabeth; Maxwell, Theresa G. (Technical Monitor)

    2002-01-01

    Planning and scheduling systems organize "tasks" into a timeline or schedule. The tasks are defined within the scheduling system in logical containers called models. The dictionary might define a model of this type as "a system of things and relations satisfying a set of rules that, when applied to the things and relations, produce certainty about the tasks that are being modeled." One challenging domain for a planning and scheduling system is the operation of on-board experiment activities for the Space Station. The equipment used in these experiments is some of the most complex hardware ever developed by mankind, the information sought by these experiments is at the cutting edge of scientific endeavor, and the procedures for executing the experiments are intricate and exacting. Scheduling is made more difficult by a scarcity of space station resources. The models to be fed into the scheduler must describe both the complexity of the experiments and procedures (to ensure a valid schedule) and the flexibilities of the procedures and the equipment (to effectively utilize available resources). Clearly, scheduling space station experiment operations calls for a "maximally expressive" modeling schema. Modeling even the simplest of activities cannot be automated; no sensor can be attached to a piece of equipment that can discern how to use that piece of equipment; no camera can quantify how to operate a piece of equipment. Modeling is a human enterprise-both an art and a science. The modeling schema should allow the models to flow from the keyboard of the user as easily as works of literature flowed from the pen of Shakespeare. The Ground Systems Department at the Marshall Space Flight Center has embarked on an effort to develop a new scheduling engine that is highlighted by a maximally expressive modeling schema. This schema, presented in this paper, is a synergy of technological advances and domain-specific innovations.

  20. Maximality of shoulder external rotation effort in patients presenting with work related injury: the clinical applicability of the DEC parameter.

    PubMed

    Chaler, Joaquim; Pujol, Eduard; Unyó, Carme; Quintana, Salvador; Müller, Bertram; Garreta, Roser; Javierre, Casimiro; Dvir, Zeevi

    2013-08-01

    The aim of the present study is to examine the applicability of the isokinetic DEC parameter for identifying submaximal effort in workers with potential weakness of the shoulder external rotators. A previous study indicated that the DEC was a powerful identifier of submaximal effort of shoulder external rotation in normal volunteers. Its applicability in shoulder injury patients is of specific interest. Thus, a retrospective study of 74 (33 female and 41 male) patients who claimed compensation for work-related shoulder injury was designed. 52 patients had their injured side DEC values within the normal range and were thus labeled as maximal performers. Ten patients had higher than cutoff DEC values, indicating submaximal effort whereas 12 patients had exceedingly low DEC values. Gender comparison showed a significantly different proportion of maximal performers. Strength deficits registered in patients demonstrating maximal performance correlated with the final outcome. The findings support the application of the DEC for determination of the extent of weakness of shoulder external rotators in male patients. In terms of shoulder external rotators status in male worker injury, the results support the application of isokinetic tests both in the clinical and medicolegal sense. However, the gender discrepancy warrants further research.

  1. Maximal acyclic agreement forests.

    PubMed

    Voorkamp, Josh

    2014-10-01

    Finding the hybridization number of a pair or set of trees, [Formula: see text], is a well-studied problem in phylogenetics and is equivalent to finding a maximum acyclic agreement forest (MAAF) for [Formula: see text]. This article defines a new type of acyclic agreement forest called a maximal acyclic agreement forest (mAAF). The property for which mAAFs are "simplest" is more general and could be considered more biologically relevant than the corresponding property for MAAFs, and the set of MAAFs for any [Formula: see text] is a subset of the set of mAAFs for [Formula: see text]. This article also presents two new algorithms; one finds a mAAF for any [Formula: see text] in polynomial time and the other is an exhaustive search that finds all mAAFs for some [Formula: see text], which is also a new approach to finding the hybridization number when applied to a pair of trees. The exhaustive search algorithm is applied to a real world data set, and the findings are compared to previous results.

  2. Maximizing relationship possibilities: relational maximization in romantic relationships.

    PubMed

    Mikkelson, Alan C; Pauley, Perry M

    2013-01-01

    Using Rusbult's (1980) investment model and Schwartz's (2000) conceptualization of decision maximization, we sought to understand how an individual's propensity to maximize his or her decisions factored into investment, satisfaction, and awareness of alternatives in romantic relationships. In study one, 275 participants currently involved in romantic relationships completed measures of maximization, satisfaction, investment size, quality of alternatives, and commitment. In study two, 343 participants were surveyed as part of the creation of a scale of relational maximization. Results from both studies revealed that the tendency to maximize (in general and in relationships specifically) was negatively correlated with satisfaction, investment, and commitment, and positively correlated with quality of alternatives. Furthermore, we found that satisfaction and investments mediated the relationship between maximization and relationship commitment.

  3. Isokinetic and isometric strength-endurance after 6 hours of immersion and 6 degrees head-down tilt in men

    NASA Technical Reports Server (NTRS)

    Shaffer-Bailey, M.; Greenleaf, J. E.; Hutchinson, T. M.

    1996-01-01

    PURPOSE: To determine weight (water) loss levels for onset of muscular strength and endurance changes during deconditioning. METHODS: Seven men (27-40 yr) performed maximal shoulder-, knee-, and ankle-joint isometric (0 degree.s(-1) load) and isokinetic (60 degrees, 120 degrees, 180 degrees.s(-1) velocity) exercise tests during ambulatory control (AC), after 6 h of 6 degrees head-down tilt (HDT; dry-bulb temp. = 23.2 +/- SD 0.6 degrees C, relative humidity = 31.1+/- 11.1%) and after 6 h of 80 degrees foot-down head-out water immersion (WI; water temp. = 35.0 +/- SD 0.1 degree C) treatments. RESULTS: Weight (water) loss after HDT (1.10 +/- SE 0.14 kg, 1.4 +/- 0.2% body wt) and WI (1.54+/- 0.19 kg, 2.0 +/- 0.2% body wt) were not different, but urinary excretion with WI (1,354 +/- 142 ml.6 h(-1)) was 28% greater (p < 0.05) than that of 975 +/- 139 ml.6 h(-1) with HDT. Muscular endurance (total work; maximal flexion-extension of the non-dominant knee at 180 degrees.s(-1) for 30 s) was not different between AC and the WI or HDT treatments. Shoulder-, knee-, and ankle-joint strength was unchanged except for three knee-joint peak torques: AC torque (120 degrees.s(-1), 285 +/- 20 Nm) decreased to 268 +/- 21 Nm (delta = -6%, p < 0.05) with WI; and AC torques (180 degrees.s(-1), 260 +/- 19 Nm) decreased to 236 +/- 15 Nm (delta = -9%, p < 0.01) with HDT, and to 235 +/- 19 Nm (delta = -10%, p < 0.01) with WI. CONCLUSION: Thus, the total body hypohydration threshold level for shoulder- and ankle-joint strength and endurance decrements is more than 2% body weight (water) loss, while significant reduction in knee-joint muscular strength-endurance occurred only at moderate (120 degrees.s(-1) and lighter (180 degrees.s(-1)) loads with body weight loss of 1.4-2.0% following WI or HDT, respectively. These weight (water) losses and knee-joint strength decrements are somewhat less than the mean weight loss of 2.6% and knee-joint strength decrements of 6-20% of American astronauts after

  4. Isokinetic and isometric strength-endurance after 6 hours of immersion and 6 degrees head-down tilt in men

    NASA Technical Reports Server (NTRS)

    Shaffer-Bailey, M.; Greenleaf, J. E.; Hutchinson, T. M.

    1996-01-01

    PURPOSE: To determine weight (water) loss levels for onset of muscular strength and endurance changes during deconditioning. METHODS: Seven men (27-40 yr) performed maximal shoulder-, knee-, and ankle-joint isometric (0 degree.s(-1) load) and isokinetic (60 degrees, 120 degrees, 180 degrees.s(-1) velocity) exercise tests during ambulatory control (AC), after 6 h of 6 degrees head-down tilt (HDT; dry-bulb temp. = 23.2 +/- SD 0.6 degrees C, relative humidity = 31.1+/- 11.1%) and after 6 h of 80 degrees foot-down head-out water immersion (WI; water temp. = 35.0 +/- SD 0.1 degree C) treatments. RESULTS: Weight (water) loss after HDT (1.10 +/- SE 0.14 kg, 1.4 +/- 0.2% body wt) and WI (1.54+/- 0.19 kg, 2.0 +/- 0.2% body wt) were not different, but urinary excretion with WI (1,354 +/- 142 ml.6 h(-1)) was 28% greater (p < 0.05) than that of 975 +/- 139 ml.6 h(-1) with HDT. Muscular endurance (total work; maximal flexion-extension of the non-dominant knee at 180 degrees.s(-1) for 30 s) was not different between AC and the WI or HDT treatments. Shoulder-, knee-, and ankle-joint strength was unchanged except for three knee-joint peak torques: AC torque (120 degrees.s(-1), 285 +/- 20 Nm) decreased to 268 +/- 21 Nm (delta = -6%, p < 0.05) with WI; and AC torques (180 degrees.s(-1), 260 +/- 19 Nm) decreased to 236 +/- 15 Nm (delta = -9%, p < 0.01) with HDT, and to 235 +/- 19 Nm (delta = -10%, p < 0.01) with WI. CONCLUSION: Thus, the total body hypohydration threshold level for shoulder- and ankle-joint strength and endurance decrements is more than 2% body weight (water) loss, while significant reduction in knee-joint muscular strength-endurance occurred only at moderate (120 degrees.s(-1) and lighter (180 degrees.s(-1)) loads with body weight loss of 1.4-2.0% following WI or HDT, respectively. These weight (water) losses and knee-joint strength decrements are somewhat less than the mean weight loss of 2.6% and knee-joint strength decrements of 6-20% of American astronauts after

  5. COPD: maximization of bronchodilation.

    PubMed

    Nardini, Stefano; Camiciottoli, Gianna; Locicero, Salvatore; Maselli, Rosario; Pasqua, Franco; Passalacqua, Giovanni; Pela, Riccardo; Pesci, Alberto; Sebastiani, Alfredo; Vatrella, Alessandro

    2014-01-01

    The most recent guidelines define COPD in a multidimensional way, nevertheless the diagnosis is still linked to the limitation of airflow, usually measured by the reduction in the FEV1/FVC ratio below 70%. However, the severity of obstruction is not directly correlated to symptoms or to invalidity determined by COPD. Thus, besides respiratory function, COPD should be evaluated based on symptoms, frequency and severity of exacerbations, patient's functional status and health related quality of life (HRQoL). Therapy is mainly aimed at increasing exercise tolerance and reducing dyspnea, with improvement of daily activities and HRQoL. This can be accomplished by a drug-induced reduction of pulmonary hyperinflation and exacerbations frequency and severity. All guidelines recommend bronchodilators as baseline therapy for all stages of COPD, and long-acting inhaled bronchodilators, both beta-2 agonist (LABA) and antimuscarinic (LAMA) drugs, are the most effective in regular treatment in the clinically stable phase. The effectiveness of bronchodilators should be evaluated in terms of functional (relief of bronchial obstruction and pulmonary hyperinflation), symptomatic (exercise tolerance and HRQoL), and clinical improvement (reduction in number or severity of exacerbations), while the absence of a spirometric response is not a reason for interrupting treatment, if there is subjective improvement in symptoms. Because LABA and LAMA act via different mechanisms of action, when administered in combination they can exert additional effects, thus optimizing (i.e. maximizing) sustained bronchodilation in COPD patients with severe airflow limitation, who cannot benefit (or can get only partial benefit) by therapy with a single bronchodilator. Recently, a fixed combination of ultra LABA/LAMA (indacaterol/glycopyrronium) has shown that it is possible to get a stable and persistent bronchodilation, which can help in avoiding undesirable fluctuations of bronchial calibre.

  6. Maximal eccentric and concentric strength discrepancies between young men and women for dynamic resistance exercise.

    PubMed

    Hollander, Daniel B; Kraemer, Robert R; Kilpatrick, Marcus W; Ramadan, Zaid G; Reeves, Greg V; Francois, Michelle; Hebert, Edward P; Tryniecki, James L

    2007-02-01

    Although research has demonstrated that isokinetic eccentric (ECC) strength is 20-60% greater than isokinetic concentric (CON) strength, few data exist comparing these strength differences in standard dynamic resistance exercises. The purpose of the study was to determine the difference in maximal dynamic ECC and CON strength for 6 different resistance exercises in young men and women. Ten healthy young men (mean +/- SE, 25.30 +/- 1.34 years), and 10 healthy young women (mean +/- SE, 23.40 +/- 1.37 years) who were regular exercisers with resistance training experience participated in the study. Two sessions were performed to determine CON and ECC 1 repetitions maximum for latissimus pull-down (LTP), leg press (LP), bench press (BP), leg extension (LE), seated military press (MP), and leg curl (LC) exercises. Maximal ECC and maximal CON strength were determined on weight stack machines modified to isolate ECC and CON contractions using steel bars and pulleys such that only 1 type of contraction was performed. Within 2 weeks, participants returned and completed a retest trial in a counterbalanced fashioned. Test-retest reliability was excellent (r = 0.99) for all resistance exercise trials. Men demonstrated 20-60% greater ECC than CON strength (LTP = 32%, LP = 44%, BP = 40%, LE = 35%, MP = 49%, LC = 27%). Women's strength exceeded the proposed parameters for greater ECC strength in 4 exercises, p < 0.05 (LP = 66%, BP = 146%, MP = 161%, LC = 82%). The ECC/CON assessment could help coaches capitalize on muscle strength differences in young men and women during training to aid in program design and injury prevention and to enhance strength development.

  7. Reliability of Concentric, Eccentric and Isometric Knee Extension and Flexion when using the REV9000 Isokinetic Dynamometer.

    PubMed

    de Carvalho Froufe Andrade, Alberto César Pereira; Caserotti, Paolo; de Carvalho, Carlos Manuel Pereira; de Azevedo Abade, Eduardo André; da Eira Sampaio, António Jaime

    2013-01-01

    The aim of this study was to assess the reliability of isokinetic and ISO knee extensor and flexor muscle strength when using the REV9000 (Technogym) isokinetic dynamometer. Moreover, the reliability of several strength imbalance indices and bilateral ratios were also examined. Twenty-four physically active healthy subjects (age 23±3 years) underwent three testing sessions, two on the same day and a third, 7 days later. All sessions proceeded in the same order: five concentric contractions at 60ºs-1 followed by an isometric contraction (5 seconds) and five eccentric contractions (60ºs-1). The results of this study showed a high reproducibility in eccentric (0.95-0.97), concentric (0.95-0.96) and isometric (0.93-0.96), isokinetic strength for knee extensor and flexor muscles, thus indicating that the REV9000 isokinetic dynamometer can be used in future sports performance studies. A low-to-moderate reliability was found in the isokinetic strength bilateral ratios while the Hamstring:Quadricep concentric ratio showed moderate reliability. The highest reliability (>0.90) was observed in the dynamic control ratio (Hamstring eccentric:Quadricep concentric) which consequently confirms that it is a more valid indicator for imbalanced reciprocal parameters and can be used in rehabilitation and sports medicine.

  8. Muscle recruitment patterns of the subscapularis, serratus anterior and other shoulder girdle muscles during isokinetic internal and external rotations.

    PubMed

    Gaudet, Sylvain; Tremblay, Jonathan; Begon, Mickael

    2017-07-04

    The aims of this study were to investigate the differences in peak muscle activity and recruitment patterns during high- and low-velocity, concentric and eccentric, internal and external isokinetic shoulder rotations. Electromyographic activity of the rotator cuff and eight superficial muscles of the shoulder girdle was recorded on 25 healthy adults during isokinetic internal and external shoulder rotation at 60°/s and 240°/s. Peak muscle activity, electromyographic envelopes and peak isokinetic moments were analyzed using three-factor ANOVA and statistical parametric mapping. The subscapularis and serratus anterior showed moderate to high peak activity levels during each conditions, while the middle and posterior deltoids, upper, middle and lower trapezius, infraspinatus and supraspinatus showed higher peak activity levels during external rotations (+36.5% of maximum voluntary activation (MVA)). The pectoralis major and latissimus dorsi were more active during internal rotations (+40% of MVA). Only middle trapezius and pectoralis major electromyographic activity decreased with increasing velocity. Peak muscle activity was similar or lower during eccentric contractions, although the peak isokinetic moment increased by 35% on average. The subscapularis and serratus anterior appear to be important stabilizers of the glenohumeral joint and scapula. Isokinetic eccentric training at high velocities may allow for faster recruitment of the shoulder girdle muscles, which could improve joint stability during shoulder internal and external rotations.

  9. Systematic Review and Meta-Analysis of Predictors of Military Task Performance: Maximal Lift Capacity.

    PubMed

    Hydren, Jay R; Borges, Alexander S; Sharp, Marilyn A

    2017-04-01

    Hydren, JR, Borges, AS, and Sharp, MA. Systematic review and meta-analysis of predictors of military task performance: maximal lift capacity. J Strength Cond Res 31(4): 1142-1164, 2017-Physical performance tests (e.g., physical employment tests, return-to-duty tests) are commonly used to predict occupational task performance to assess the ability of individuals to do a job. The purpose of this systematic review was to identify predictive tests that correlate well with maximal lifting capacity in military personnel. Three databases were searched and experts in the field were contacted, resulting in the identification of 9 reports confined to military personnel that presented correlations between predictor tests and job tasks that measured maximal lift capacity. These 9 studies used 9 variations of a maximal lift capacity test, which were pooled to evaluate comparisons. The predictive tests were categorized into 10 fitness domains, which in ranked order were as follows: body mass and composition, absolute aerobic capacity, dynamic strength, power, isometric strength, strength-endurance, speed, isokinetic strength, flexibility, and age. Limitations of these data include a restricted age range (95% confidence interval [95% CI], 20-35; no correlations to maximal lift capacity) and the limited number of comparisons available within the cited studies. Weighted mean correlations ((Equation is included in full-text article.)) and 95% CI were calculated for each test. Lean body mass (kg) was the strongest overall predictor ((Equation is included in full-text article.); 95% CI, 0.697-0.966). Tests of dynamic strength had stronger correlations than strength endurance ((Equation is included in full-text article.), 95% CI, 0.69-0.89 vs. (Equation is included in full-text article.), 95% CI, 0.21-0.61). The following 6 domains of physical performance predictive tests had pooled correlations of 0.40 or greater for combined-sex samples: dynamic strength, power, isometric strength

  10. In vivo maximal fascicle-shortening velocity during plantar flexion in humans.

    PubMed

    Hauraix, Hugo; Nordez, Antoine; Guilhem, Gaël; Rabita, Giuseppe; Dorel, Sylvain

    2015-12-01

    Interindividual variability in performance of fast movements is commonly explained by a difference in maximal muscle-shortening velocity due to differences in the proportion of fast-twitch fibers. To provide a better understanding of the capacity to generate fast motion, this study aimed to 1) measure for the first time in vivo the maximal fascicle-shortening velocity of human muscle; 2) evaluate the relationship between angular velocity and fascicle-shortening velocity from low to maximal angular velocities; and 3) investigate the influence of musculo-articular features (moment arm, tendinous tissues stiffness, and muscle architecture) on maximal angular velocity. Ultrafast ultrasound images of the gastrocnemius medialis were obtained from 31 participants during maximal isokinetic and light-loaded plantar flexions. A strong linear relationship between fascicle-shortening velocity and angular velocity was reported for all subjects (mean R(2) = 0.97). The maximal shortening velocity (V(Fmax)) obtained during the no-load condition (NLc) ranged between 18.8 and 43.3 cm/s. V(Fmax) values were very close to those of the maximal shortening velocity (V(max)), which was extrapolated from the F-V curve (the Hill model). Angular velocity reached during the NLc was significantly correlated with this V(Fmax) (r = 0.57; P < 0.001). This finding was in agreement with assumptions about the role of muscle fiber type, whereas interindividual comparisons clearly support the fact that other parameters may also contribute to performance during fast movements. Nevertheless, none of the biomechanical features considered in the present study were found to be directly related to the highest angular velocity, highlighting the complexity of the upstream mechanics that lead to maximal-velocity muscle contraction.

  11. Maximal cuts in arbitrary dimension

    NASA Astrophysics Data System (ADS)

    Bosma, Jorrit; Sogaard, Mads; Zhang, Yang

    2017-08-01

    We develop a systematic procedure for computing maximal unitarity cuts of multiloop Feynman integrals in arbitrary dimension. Our approach is based on the Baikov representation in which the structure of the cuts is particularly simple. We examine several planar and nonplanar integral topologies and demonstrate that the maximal cut inherits IBPs and dimension shift identities satisfied by the uncut integral. Furthermore, for the examples we calculated, we find that the maximal cut functions from different allowed regions, form the Wronskian matrix of the differential equations on the maximal cut.

  12. Electromyographic analysis of repeated bouts of eccentric exercise.

    PubMed

    McHugh, M P; Connolly, D A; Eston, R G; Gartman, E J; Gleim, G W

    2001-03-01

    The repeated bout effect refers to the protective effect provided by a single bout of eccentric exercise against muscle damage from a similar subsequent bout. The aim of this study was to determine if the repeated bout was associated with an increase in motor unit activation relative to force production, an increased recruitment of slow-twitch motor units or increased motor unit synchronization. Surface electromyographic (EMG) signals were recorded from the hamstring muscles during two bouts of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions separated by 2 weeks. The EMG per unit torque and median frequency were analysed. The initial bout of eccentric exercise resulted in strength loss, pain and muscle tenderness, while the repeated eccentric bout resulted in a slight increase in strength, no pain and no muscle tenderness (bout x time effects, P < 0.05). Strength, pain and tenderness were unaffected by either bout of concentric exercise. The EMG per unit torque and median frequency were not different between the initial and repeated bouts of eccentric exercise. The EMG per unit torque and median frequency increased during both bouts of eccentric exercise (P < 0.01) but did not change during either concentric bout. In conclusion, there was no evidence that the repeated bout effect was due to a neural adaptation.

  13. Comparative study on isokinetic capacity of knee and ankle joints by functional injury

    PubMed Central

    Jeon, Kyoungkyu; Seo, Byoung-Do; Lee, Sang-Ho

    2016-01-01

    [Purpose] To collect basic data for exercise programs designed to enhance functional knee and ankle joint stability based on isokinetic measurement and muscle strength evaluations in normal and impaired functional states. [Subjects and Methods] Twenty-four subjects were randomly assigned to the athlete group and the control group (n = 12 each). Data were collected of isokinetic knee extensor and flexor strength at 60°/sec, 180°/sec, and 240°/sec and ankle plantar and dorsiflexor strength at 30°/sec and 120°/sec. [Results] Significant intergroup differences were observed in peak torque of the right extensors at 60°/sec, 180°/sec, and 240°/sec and the right flexors at 240°/sec. Significant differences were observed in peak torque/body weight in the right extensors at 60°/sec, 180°/sec, and 240°/sec and in the right flexors at 180°/sec and 240°/sec. Significant peak torque differences were noted in the left ankle joint dorsiflexor at 30°/sec and 120°/sec, right plantar flexor at 120°/sec, left plantar flexor at 30°/sec, left dorsiflexor at 30°/sec and 120°/sec, and right dorsiflexor at 120°/sec. [Conclusion] Isokinetic evaluation stimulates muscle contraction at motion-dependent speeds and may contribute to the development of intervention programs to improve knee and ankle joint function and correct lower-extremity instability. PMID:26957768

  14. Shoulder isokinetic profile of male handball players of the Brazilian National Team

    PubMed Central

    Andrade, Marília S.; Vancini, Rodrigo L.; de Lira, Claudio A. B.; Mascarin, Naryana C.; Fachina, Rafael J. F. G.; da Silva, Antonio C.

    2013-01-01

    Background Data obtained on an isokinetic dynamometer are useful to characterize muscle status and have been reported in muscle imbalance studies in different types of sport. However, few studies have assessed elite handball players to establish reference values. Objective The purpose of this study was to compare, for the dominant (D) and non-dominant (ND) side, the isokinetic profile of shoulder rotator muscle strength between male handball players (H) and asymptomatic non-athletes (NA). Method Isokinetic concentric and eccentric strength tests for D upper limbs were performed by the H group (n=20) and the NA group (n=12). Internal and external rotator muscle peak torque in concentric action was assessed at 60°/s and 300°/s and in eccentric action at 300°/s. We also calculated conventional balance (the ratio of external rotator peak torque to internal rotator peak torque in concentric action) and functional balance (the ratio of external rotator peak torque in eccentric action to internal rotator peak torque in concentric action). Results In the H group, dominant limbs were stronger in concentric action for external rotation at 60 and 300°/s. The conventional balance ratio for the D side was significantly lower at 60 and 300°/s for H compared to NA. The functional ratio for the D side was significantly lower at 300º/s for H compared to NA. Conclusions Compared to asymptomatic non-athletes, handball players presented significant muscular imbalance resulting from daily sports practice, a known risk factor for shoulder injuries. PMID:24271090

  15. Normal isometric and isokinetic peak torques of hamstring and quadriceps muscles in young adult Saudi males.

    PubMed

    Alangari, Abdulrahman S; Al-Hazzaa, Hazzaa M

    2004-07-01

    To provide reference data for peak isometric and isokinetic muscle strength of hamstring and quadriceps muscles in young adult Saudi males. The strength of left and right quadriceps and hamstrings leg muscles was assessed in 132 college-male students in the campus of King Saud University, Riyadh, Kingdom of Saudi Arabia in the year 2002 using a Cybex machine and a standardized protocol at the following velocities: 0, 60, 180, and 300 degrees/sec. Isometric strength (0 degrees/sec) was assessed at 65 degrees angle of knee flexion. Isometric flexion strength was 9.3% higher in the right leg compared to the left (p < 0.01), while there was no significant difference between the 2 legs in extension. In isokinetic strength, there was a decrease in both extension and flexion strength with increasing velocity. However, only in flexion strength a significant right-left difference was observed. Flexion/extension peak concentric torque ratio relative to angular velocity varied from 59.9-63.3% in the right leg and from 55.8-59.9% in the left leg, with significant difference (p < 0.02) between the 2 legs. In addition, the angle of peak torque decreased with increasing velocity at knee extension but increased at knee flexion. Young Saudi males appeared to have similar isometric peak strength in the knee extensors but not in the flexors when compared to previously published research. Isokinetic extension strength at 60 degrees/sec in the Saudi males is lower than values reported for untrained males elsewhere. Furthermore, the hamstrings/quadriceps ratio in Saudi males seems to be within the recommended range of appropriate muscle function.

  16. ARE THERE DIFFERENCES IN STRENGTH TESTS USING ISOKINETIC DYNAMOMETRY BETWEEN FIELD AND INDOOR PROFESSIONAL SOCCER PLAYERS?

    PubMed Central

    de Aguiar Leonardi, Adriano Barros; Martinelli, Mauro Olivio; Junior, Aires Duarte

    2015-01-01

    Objective: The objective of this study was to conduct a comparative analysis on isokinetic strength assessments between field and indoor male professional soccer players and correlate the findings with the higher levels of injury risk described in the literature. Methods: We analyzed 16 field soccer players and 15 indoor soccer players. All these professionals were male. Isokinetic muscle strength assessments were made on their knees. Results: The mean weight was 81.81 kg for field soccer and 80.33 kg for indoor soccer. The right and left peak extensor torque left and right for field soccer and indoor soccer were, respectively, 302.50 and 313.31 Nm and 265.20 and 279.80 Nm, and for flexors, 178 and 184.88 Nm and 158.27 and 154 Nm. The peak torque rates according to body weight for the left and right extensors for field soccer and indoor soccer were, respectively, 3.84 and 3.7 Nm/kg and 3.32 and 3.52 Nm/kg, and for flexors, 2.17 and 2.26 Nm/kg and 1.98 and 1.93 Nm/kg. The balance relationships between flexors and extensors on the right and left sides for field soccer and indoor soccer were, respectively, 59.81 and 59.44% and 60.47% and 54.80%. The relationships for extensors between the right and left sides for field soccer and indoor soccer were, respectively, 11.44 and 9.20%, and for the flexors, 7.31 and 8.80%. Conclusions: In accordance with international parameters, comparative analysis on isokinetic strength assessments between field and indoor male professional soccer players before the season showed that there was muscle balance and low probability of injury. There were no statistically significant differences in the parameters analyzed between the players of the two types of soccer. PMID:27042649

  17. 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

  18. Comparative study on isokinetic capacity of knee and ankle joints by functional injury.

    PubMed

    Jeon, Kyoungkyu; Seo, Byoung-Do; Lee, Sang-Ho

    2016-01-01

    [Purpose] To collect basic data for exercise programs designed to enhance functional knee and ankle joint stability based on isokinetic measurement and muscle strength evaluations in normal and impaired functional states. [Subjects and Methods] Twenty-four subjects were randomly assigned to the athlete group and the control group (n = 12 each). Data were collected of isokinetic knee extensor and flexor strength at 60°/sec, 180°/sec, and 240°/sec and ankle plantar and dorsiflexor strength at 30°/sec and 120°/sec. [Results] Significant intergroup differences were observed in peak torque of the right extensors at 60°/sec, 180°/sec, and 240°/sec and the right flexors at 240°/sec. Significant differences were observed in peak torque/body weight in the right extensors at 60°/sec, 180°/sec, and 240°/sec and in the right flexors at 180°/sec and 240°/sec. Significant peak torque differences were noted in the left ankle joint dorsiflexor at 30°/sec and 120°/sec, right plantar flexor at 120°/sec, left plantar flexor at 30°/sec, left dorsiflexor at 30°/sec and 120°/sec, and right dorsiflexor at 120°/sec. [Conclusion] Isokinetic evaluation stimulates muscle contraction at motion-dependent speeds and may contribute to the development of intervention programs to improve knee and ankle joint function and correct lower-extremity instability.

  19. 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 (0.960isokinetic testing of mechanical capacities of knee extensors and, if supported by further research, other muscles. This brief and fatigue-free testing procedure could discern between muscle force, velocity, and power-producing capacities. © Georg Thieme Verlag KG Stuttgart · New York.

  20. Strength deficits of the shoulder complex during isokinetic testing in people with chronic stroke

    PubMed Central

    Nascimento, Lucas R.; Teixeira-Salmela, Luci F.; Polese, Janaine C.; Ada, Louise; Faria, Christina D. C. M.; Laurentino, Glória E. C.

    2014-01-01

    OBJECTIVES: To examine the strength deficits of the shoulder complex after stroke and to characterize the pattern of weakness according to type of movement and type of isokinetic parameter. METHOD: Twelve chronic stroke survivors and 12 age-matched healthy controls had their shoulder strength measured using a Biodex isokinetic dynamometer. Concentric measures of peak torque and work during shoulder movements were obtained in random order at speeds of 60°/s for both groups and sides. Type of movement was defined as scapulothoracic (protraction and retraction), glenohumeral (shoulder internal and external rotation) or combined (shoulder flexion and extension). Type of isokinetic parameter was defined as maximum (peak torque) or sustained (work). Strength deficits were calculated using the control group as reference. RESULTS: The average strength deficit for the paretic upper limb was 52% for peak torque and 56% for work. Decreases observed in the non-paretic shoulder were 21% and 22%, respectively. Strength deficit of the scapulothoracic muscles was similar to the glenohumeral muscles, with a mean difference of 6% (95% CI -5 to 17). Ability to sustain torque throughout a given range of motion was decreased as much as the peak torque, with a mean difference of 4% (95% CI -2 to 10). CONCLUSIONS: The findings suggest that people after stroke might benefit from strengthening exercises directed at the paretic scapulothoracic muscles in addition to exercises of arm elevation. Clinicians should also prescribe different exercises to improve the ability to generate force and the ability to sustain the torque during a specific range of motion. PMID:25003280

  1. The Effect of Concentric Isokinetic Strength Training of the Quadriceps Femoris on Electromyography and Muscle Strength in the Trained and Untrained Limb.

    ERIC Educational Resources Information Center

    Evetovich, Tammy K.; Housh, Terry J.; Housh, Dona J.; Johnson, Glen O.; Smith, Douglas B.; Ebersole, Kyle T.

    2001-01-01

    Examined the effects of unilateral concentric isokinetic leg extension training on peak torque and electromyographic (EMG) responses in trained and untrained limbs. Adult men participated in training and control groups. Overall, unilateral concentric isokinetic strength training induced strength increases in trained as well as untrained limbs.…

  2. The Effect of Concentric Isokinetic Strength Training of the Quadriceps Femoris on Electromyography and Muscle Strength in the Trained and Untrained Limb.

    ERIC Educational Resources Information Center

    Evetovich, Tammy K.; Housh, Terry J.; Housh, Dona J.; Johnson, Glen O.; Smith, Douglas B.; Ebersole, Kyle T.

    2001-01-01

    Examined the effects of unilateral concentric isokinetic leg extension training on peak torque and electromyographic (EMG) responses in trained and untrained limbs. Adult men participated in training and control groups. Overall, unilateral concentric isokinetic strength training induced strength increases in trained as well as untrained limbs.…

  3. The acute effect of the tongue position in the mouth on knee isokinetic test performance: a highly surprising pilot study.

    PubMed

    di Vico, Rosa; Ardigò, Luca Paolo; Salernitano, Gianluca; Chamari, Karim; Padulo, Johnny

    2013-10-01

    The tongue involvement within the isokinetic knee extension/flexion exercises has been investigated. Eighteen participants randomly underwent isokinetic testing at 90 and 180°/s with three different tongue positions: middle position (MID, thrusting on the lingual surface of incisive teeth), lying on the lower arch of the mouth (LOW) and extended up to the palatine spot (UP). Statistical analysis of the data revealed an about 30% significant increase of knee flexion peak torque in UP with respect to MID at both angular speeds. Such a difference could have had a confounding effect on results from numerous past studies using isokinetic knee flexion testing. This study alerts future researchers about standardization of tongue position and warrants further investigations on the explicative processes of this phenomenon.

  4. The acute effect of the tongue position in the mouth on knee isokinetic test performance: a highly surprising pilot study

    PubMed Central

    di Vico, Rosa; Ardigò, Luca Paolo; Salernitano, Gianluca; Chamari, Karim; Padulo, Johnny

    2013-01-01

    Summary The tongue involvement within the isokinetic knee extension/flexion exercises has been investigated. Eighteen participants randomly underwent isokinetic testing at 90 and 180°/s with three different tongue positions: middle position (MID, thrusting on the lingual surface of incisive teeth), lying on the lower arch of the mouth (LOW) and extended up to the palatine spot (UP). Statistical analysis of the data revealed an about 30% significant increase of knee flexion peak torque in UP with respect to MID at both angular speeds. Such a difference could have had a confounding effect on results from numerous past studies using isokinetic knee flexion testing. This study alerts future researchers about standardization of tongue position and warrants further investigations on the explicative processes of this phenomenon. PMID:24596696

  5. Prevalence of abnormal patellofemoral congruence in elite American football players and association with quadriceps isokinetic testing.

    PubMed

    Brown, Christopher A; Carragee, Cat; Sox-Harris, Alex; Merchant, Alan C; Mcadams, Timothy R

    2014-02-01

    Abnormal patellofemoral joint alignment has been discussed as a potential risk factor for patellofemoral disorders and can impact the longevity of any elite athlete's career. The prevalence of abnormal patellofemoral congruence in elite American football athletes is similar to the general population and does not have a relationship with quadriceps isokinetic testing. A total of 125 athletes (220 knees) from the 2011 National Football League (NFL) Combine database who had radiographic and isokinetic studies were reviewed. Congruence angles (CA) and lateral patellofemoral angles (LPA) were calculated on a Merchant radiographic view. Isokinetic testing was used to determine quadriceps-to-hamstring strength (Q/H) ratio and side-to-side deficits. The relationships between abnormal CA and LPA with Q/H ratios, side-to-side deficits, and body mass index (BMI) were examined in separate logistic regression models. A Chi-square test was used to examine the association between CA and player position. Of all, 26.8% of the knees (95% CI: 21.1-33.2%) had an abnormal CA. Knees with normal CA (n = 161) did not significantly differ from those with an abnormal CA (n  = 59) in Q/H ratios (mean: 0.699 vs. 0.728, p = 0.19) or side-to-side quadriceps deficits (mean: 4.0 vs. 1.24, p  = 0.45). For each point increase in BMI, the odds ratio (OR) of abnormal congruence increased by 11.4% (p = 0.002). Of all the knees, 4.1% (95% CI: 1.9-7.6%) had an abnormal LPA, and this was not associated with Q/H ratios (p  =  0.13). For each point increase in BMI, the odds of abnormal LPA increased by 16% (p  = 0.036). CA abnormality had much higher odds of having an abnormal LPA (OR: 5.96, p = 0.014). We found that abnormal patellofemoral radiographic alignment in elite American football players is relatively common and there was no association with isokinetic testing. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  6. Clinical and isokinetic comparison between tenotomy and tenodesis in biceps pathologies.

    PubMed

    Sentürk, Ihsan; Ozalay, Metin; Akpınar, Sercan; Leblebici, Berrin; Cınar, B Murat; Tuncay, Cengiz

    2011-01-01

    The purpose of this study to compare clinical and isokinetic results of patients who underwent biceps tenotomy or tenodesis for chronic tenosynovitis. Arthroscopic biceps tenotomy, arthroscopy assisted or arthroscopic biceps tenodesis were done in 20 patients who had diagnosis of chronic tenosynovitis and in whom conservative treatment was not helpful. Rotator cuff repair and acromioplasty was performed in 18 patients and acromioplasty alone in two patients in addition to biceps surgery. Arthroscopic biceps tenotomy was done in 10 patients (5 female, 5 male; mean age 63, range 53-75), 10 patients underwent tenodesis out of which arthroscopy assisted biceps tenodesis was done in 8 patients and all arthroscopic biceps tenodesis was done in 2 patients (4 female, 6 male; mean age 57, range 49-66). All patients were evaluated with Constant and UCLA scores preoperatively and postoperatively. The average follow-up of the patients 3,1 years (between 1-8 years). Isokinetically elbow flexion and forearm supination were compared using the Cybex (Biodex 3, Cybex Biomedical System, NY, USA) machine. Pre-operative results of each group were compared with the postoperative results, using Mann-Whitney U test. Preoperative average constant scores of tenotomy group were 64.40, whereas postoperative scores were 89.50 (p=0.002), and preoperative average constant scores of tenodesis group were 62.80, whereas postoperative scores were 86.70 (p=0.003). Preoperative average UCLA scores of tenotomy group were 23.20 whereas postoperative UCLA scores 22.60 (p=0.003), preoperative average UCLA scores of tenodesis group were 30.00 whereas postoperative UCLA scores was 29.20 (p=0.004). In both groups statistically significant improvement of UCLA and Constant scores was detected. Comparison between Constant, UCLA scores and isokinetic measurements of both groups showed no statistically significant difference (p>0.05). No complication was noted. In the treatment of chronic tenosynovitis, biceps

  7. Isokinetic muscle performance of the hip and ankle muscles in women with fibromyalgia.

    PubMed

    Yetişgin, Alparslan; Tiftik, Tülay; Kara, Murat; Karabay, İlkay; Akkuş, Selami; Ersöz, Murat

    2016-06-01

    To compare isokinetic muscle performances of a proximal (hip) and a distal (ankle) muscle of fibromyalgia syndrome (FMS) patients with those of age- and body mass index (BMI)-matched healthy subjects. Thirty female patients with FMS (mean age: 41.5 ± 6.7 years [range, 27-54]) and 30 age- (mean age: 40.6 ± 6.0 years [range, 27-54]) and BMI-matched female healthy controls were consecutively enrolled. Demographic and clinical characteristics of the subjects were recorded. Isokinetic measurements of hip and ankle flexion and extension at angular velocities of 60°/s and 180°/s, peak torques, flexor-extensor torque ratios, muscle fatigue resistance values and average power were obtained. Mean disease duration of FMS patients was 2.4 ± 1.9 years. Mean weight, height and BMI values were 70.4 ± 12.5 kg, 159.5 ± 6.0 cm and 27.7 ± 4.7 kg/m² (FMS patients) and 69.3 ± 10.1 kg, 161.7 ± 6.2 cm and 26.6 ± 4.3 kg/m² (control subjects), respectively (all P > 0.05). All isokinetic values were statistically decreased in the FMS group when compared with the control group, except for the peak torques at angular velocity of 180°/s on flexion of the hip and extension of the ankle and the total work and average power on extension of the ankle. We did not find any correlation between isokinetic values and disease related parameters of FMS patients. In the light of our results, we may conclude that muscle strength and muscle fatigue seem to decrease in FMS patients' both proximal and distal lower extremity muscles. © 2013 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

  8. Inter- and intrarater reliability of four single-legged hop tests and isokinetic muscle torque measurements in children.

    PubMed

    Johnsen, Marianne Bakke; Eitzen, Ingrid; Moksnes, Håvard; Risberg, May Arna

    2015-07-01

    Single-legged hop tests and isokinetic muscle torque are common outcome measures in the evaluation of knee function. The reliability of the single-legged hop tests in children has not been documented. The aim was to examine inter- and intrarater reliability of four single-legged hop tests and isokinetic muscle torque measurements in children. Twenty-eight sports-active children (12.4 ± 0.3 years old) were tested three times in two test sessions separated by 1 week. They performed four single-legged hop tests and concentric isokinetic torque measurements during knee extension and flexion. Inter- and intrarater reliability were calculated using the intraclass correlation coefficient (ICC 2,1). Relative terms of the standard error of measurement (SEM %) and smallest real difference(SRD %) were emphasized to allow comparison between the different variables. Twenty-six children were included for statistical analysis. ICCs for inter- and intrarater reliability were moderate to high for the hop tests (0.62-.91) and isokinetic measurements (0.76-0.87). SEMs % were low for the hop tests (3.9-7.4 %) and the isokinetic measurements (5.2-8.9 %). SRDs % were 20.5 % or less for the hop tests, 15.7 % or less for knee extension, and 24.6 % or less for knee flexion. The single-legged hop tests and isokinetic muscle torque measurements demonstrated moderate-to high reliability with low measurement error in sports-active children. A change above 20.5 % for the single-legged hop tests, 15.7 % for knee extension, and 24.6 % for knee flexion is necessary to represent a real change in knee function. Level of evidence III.

  9. Correlation of isokinetic and novel hand-held dynamometry measures of knee flexion and extension strength testing.

    PubMed

    Whiteley, Rod; Jacobsen, Phillip; Prior, Simon; Skazalski, Christopher; Otten, Roald; Johnson, Amanda

    2012-09-01

    Describe inter-rater reliability of, and correlations between a novel method of isometric knee extension and flexion and eccentric knee flexion strength using hand-held dynamometry and isokinetic testing for flexion/extension in the knees of athletic participants. Document strength data normalized to the individual's limb muscle mass. Observational and reliability study. Inter-rater reliability for each of the hand-held dynamometry measures was established in both legs of 10 volunteers (6 male). During routine annual screening, 216 male professional football (soccer) players were examined using these same measures in addition to performing an isokinetic evaluation of knee flexion and extension strength. Intra-class correlation coefficients for inter-rater reliability, Pearson r correlations between hand-held dynamometry and isokinetic dynamometry were calculated. Peak torque, peak torque normalized to: body weight; lean body mass; and lean limb mass were documented. Excellent inter-rater reliability was demonstrated with intra-class correlation₂,₁ values of 0.90, 0.91, and 0.96, for the eccentric hamstrings, isometric hamstrings, and isometric quadriceps measures respectively. Medium to high correlations (r=0.322-0.617) which were all significant (p<0.001) were found for the comparisons between the hand-held dynamometry and isokinetic measures. We present 3 novel and reliable methods of examining knee flexion and extension strength using hand-held dynamometry which require less skill and strength on the part of the examiner than previous measures. Correlations between these measures and isokinetic dynamometry are documented. The hand-held dynamometry examinations took less than 4 min per player to conduct and may be useful in clinical practice where isokinetic examination can be difficult to implement. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  10. General review of maximal aerobic velocity measurement at laboratory. Proposition of a new simplified protocol for maximal aerobic velocity assessment.

    PubMed

    Berthon, P; Fellmann, N

    2002-09-01

    The maximal aerobic velocity concept developed since eighties is considered as either the minimal velocity which elicits the maximal aerobic consumption or as the "velocity associated to maximal oxygen consumption". Different methods for measuring maximal aerobic velocity on treadmill in laboratory conditions have been elaborated, but all these specific protocols measure V(amax) either during a maximal oxygen consumption test or with an association of such a test. An inaccurate method presents a certain number of problems in the subsequent use of the results, for example in the elaboration of training programs, in the study of repeatability or in the determination of individual limit time. This study analyzes 14 different methods to understand their interests and limits in view to propose a general methodology for measuring V(amax). In brief, the test should be progressive and maximal without any rest period and of 17 to 20 min total duration. It should begin with a five min warm-up at 60-70% of the maximal aerobic power of the subjects. The beginning of the trial should be fixed so that four or five steps have to be run. The duration of the steps should be three min with a 1% slope and an increasing speed of 1.5 km x h(-1) until complete exhaustion. The last steps could be reduced at two min for a 1 km x h(-1) increment. The maximal aerobic velocity is adjusted in relation to duration of the last step.

  11. Isokinetic knee strength qualities as predictors of jumping performance in high-level volleyball athletes: multiple regression approach.

    PubMed

    Sattler, Tine; Sekulic, Damir; Spasic, Miodrag; Osmankac, Nedzad; Vicente João, Paulo; Dervisevic, Edvin; Hadzic, Vedran

    2016-01-01

    Previous investigations noted potential importance of isokinetic strength in rapid muscular performances, such as jumping. This study aimed to identify the influence of isokinetic-knee-strength on specific jumping performance in volleyball. The secondary aim of the study was to evaluate reliability and validity of the two volleyball-specific jumping tests. The sample comprised 67 female (21.96±3.79 years; 68.26±8.52 kg; 174.43±6.85 cm) and 99 male (23.62±5.27 years; 84.83±10.37 kg; 189.01±7.21 cm) high- volleyball players who competed in 1st and 2nd National Division. Subjects were randomly divided into validation (N.=55 and 33 for males and females, respectively) and cross-validation subsamples (N.=54 and 34 for males and females, respectively). Set of predictors included isokinetic tests, to evaluate the eccentric and concentric strength capacities of the knee extensors, and flexors for dominant and non-dominant leg. The main outcome measure for the isokinetic testing was peak torque (PT) which was later normalized for body mass and expressed as PT/Kg. Block-jump and spike-jump performances were measured over three trials, and observed as criteria. Forward stepwise multiple regressions were calculated for validation subsamples and then cross-validated. Cross validation included correlations between and t-test differences between observed and predicted scores; and Bland Altman graphics. Jumping tests were found to be reliable (spike jump: ICC of 0.79 and 0.86; block-jump: ICC of 0.86 and 0.90; for males and females, respectively), and their validity was confirmed by significant t-test differences between 1st vs. 2nd division players. Isokinetic variables were found to be significant predictors of jumping performance in females, but not among males. In females, the isokinetic-knee measures were shown to be stronger and more valid predictors of the block-jump (42% and 64% of the explained variance for validation and cross-validation subsample, respectively

  12. The Measurement of Maximal (Anaerobic) Power Output on a Cycle Ergometer: A Critical Review

    PubMed Central

    Driss, Tarak; Vandewalle, Henry

    2013-01-01

    The interests and limits of the different methods and protocols of maximal (anaerobic) power (P max) assessment are reviewed: single all-out tests versus force-velocity tests, isokinetic ergometers versus friction-loaded ergometers, measure of P max during the acceleration phase or at peak velocity. The effects of training, athletic practice, diet and pharmacological substances upon the production of maximal mechanical power are not discussed in this review mainly focused on the technical (ergometer, crank length, toe clips), methodological (protocols) and biological factors (muscle volume, muscle fiber type, age, gender, growth, temperature, chronobiology and fatigue) limiting P max in cycling. Although the validity of the Wingate test is questionable, a large part of the review is dedicated to this test which is currently the all-out cycling test the most often used. The biomechanical characteristics specific of maximal and high speed cycling, the bioenergetics of the all-out cycling exercises and the influence of biochemical factors (acidosis and alkalosis, phosphate ions…) are recalled at the beginning of the paper. The basic knowledge concerning the consequences of the force-velocity relationship upon power output, the biomechanics of sub-maximal cycling exercises and the study on the force-velocity relationship in cycling by Dickinson in 1928 are presented in Appendices. PMID:24073413

  13. The measurement of maximal (anaerobic) power output on a cycle ergometer: a critical review.

    PubMed

    Driss, Tarak; Vandewalle, Henry

    2013-01-01

    The interests and limits of the different methods and protocols of maximal (anaerobic) power (Pmax) assessment are reviewed: single all-out tests versus force-velocity tests, isokinetic ergometers versus friction-loaded ergometers, measure of Pmax during the acceleration phase or at peak velocity. The effects of training, athletic practice, diet and pharmacological substances upon the production of maximal mechanical power are not discussed in this review mainly focused on the technical (ergometer, crank length, toe clips), methodological (protocols) and biological factors (muscle volume, muscle fiber type, age, gender, growth, temperature, chronobiology and fatigue) limiting Pmax in cycling. Although the validity of the Wingate test is questionable, a large part of the review is dedicated to this test which is currently the all-out cycling test the most often used. The biomechanical characteristics specific of maximal and high speed cycling, the bioenergetics of the all-out cycling exercises and the influence of biochemical factors (acidosis and alkalosis, phosphate ions…) are recalled at the beginning of the paper. The basic knowledge concerning the consequences of the force-velocity relationship upon power output, the biomechanics of sub-maximal cycling exercises and the study on the force-velocity relationship in cycling by Dickinson in 1928 are presented in Appendices.

  14. Evaluation of Suited and Unsuited Human Functional Strength Using Multipurpose, Multiaxial Isokinetic Dynamometer

    NASA Technical Reports Server (NTRS)

    Aghazadeh, Fred

    2005-01-01

    The objective of the planned summer research was to develop a procedure to determine the isokinetic functional strength of suited and unsuited participants in order to estimate the coefficient of micro-gravity suit on human strength. To accomplish this objective, the Anthropometry and Biomechanics Facility's Multipurpose, Multiaxial Isokinetic dynamometer (MMID) was used. Development of procedure involved selection and testing of seven routines to be tested on MMID. We conducted the related experiments and collected the data for 12 participants. In addition to the above objective, we developed a procedure to assess the fatiguing characteristics of suited and unsuited participants using EMG technique. We collected EMG data on 10 participants while performing a programmed routing on MMID. EMG data along with information on the exerted forces, effector speed, number of repetitions, and duration of each routine were recorded for further analysis. Finally, gathering and tabulation Of data for various human strengths for updating of MSIS (HSIS) strength requirement, which started in summer 2003, also continued.

  15. Analysis of isokinetic muscle strength for sports physiotherapy research in Korean ssireum athletes

    PubMed Central

    Noh, Ji-Woong; Park, Byoung-Sun; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Shin, Yong-Sub; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Park, Jaehong; Kim, Junghwan

    2015-01-01

    [Purpose] The purpose of the present study was to elucidate the muscle conditions such as the isokinetic muscle of Korean ssireum athletes. [Subjects and Methods] This study enrolled 25 elite ssireum athletes. We measured body composition and peak torque at an angular speed at 60°/s using an isokinetic muscle strength dynamometer. [Results] The lean body mass of the left upper limb was significantly higher than that of the right upper limb. However, the lean body mass of the left lower limb was significantly lower than that of the right lower limb. The peak torque for left elbow flexion was significantly higher than that for right elbow flexion. Conversely, the peak torque for left elbow extension was significantly lower than that for right elbow extension. Furthermore, the peak torque for the left knee was significantly lower than that for the right knee for both flexion and extension. [Conclusion] The data from this study elucidate in part the muscle conditions of Korean ssireum athletes, which can be used to establish a reference for the scientific study of sports physiotherapy. PMID:26644679

  16. Analysis of isokinetic muscle strength for sports physiotherapy research in Korean ssireum athletes.

    PubMed

    Noh, Ji-Woong; Park, Byoung-Sun; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Shin, Yong-Sub; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Park, Jaehong; Kim, Junghwan

    2015-10-01

    [Purpose] The purpose of the present study was to elucidate the muscle conditions such as the isokinetic muscle of Korean ssireum athletes. [Subjects and Methods] This study enrolled 25 elite ssireum athletes. We measured body composition and peak torque at an angular speed at 60°/s using an isokinetic muscle strength dynamometer. [Results] The lean body mass of the left upper limb was significantly higher than that of the right upper limb. However, the lean body mass of the left lower limb was significantly lower than that of the right lower limb. The peak torque for left elbow flexion was significantly higher than that for right elbow flexion. Conversely, the peak torque for left elbow extension was significantly lower than that for right elbow extension. Furthermore, the peak torque for the left knee was significantly lower than that for the right knee for both flexion and extension. [Conclusion] The data from this study elucidate in part the muscle conditions of Korean ssireum athletes, which can be used to establish a reference for the scientific study of sports physiotherapy.

  17. Velocity sedimentation of organelles at low centrifugal force in an isokinetic gradient.

    PubMed

    Pretlow, T G; Kreisberg, J I; Fine, W D; Zieman, G A; Brattain, M G; Pretlow, T P

    1978-07-15

    Mast-cell granules and polystyrene microspheres (0.600 and 1.011 micrometer in diameter) were sedimented in a previously described [Pretlow (1971) Anal. Biochem. 41, 248--255] isokinetic gradient in a low-speed centrifuge. For the analytical velocity sedimentation of organelles, this gradient offers several advantages over gradients that are commonly used for the sedimentation of organelles: (a) the density gradient (0.0008 g.ml-1.cm-1) is small, and the effective densities of organelles will change relatively little during sedimentation; (b) the densities at all points in the gradient (1.017--1.027 g/ml) are less than those in gradients commonly used for the sedimentation of organelles, the effective densities of sedimenting organelles are consequently relatively large, and the effect of density as a determinant of velocity of sedimentation is less limiting than in conventional gradients; (c) the small slope of the gradient is associated with a relatively slow increase in the viscosity encountered by the sedimenting organelle; (d) the iso-osmotic gradient is not significantly affected by the gradient medium (Ficoll), and the osmolarity can be adjusted to the desired value by the selection of an appropriate salt solution as the solvent for the Ficoll; (e) the gradient will be isokinetic for particles of densities similar to most organelles. An ultracentrifuge is not required for work with this gradient.

  18. Velocity sedimentation of organelles at low centrifugal force in an isokinetic gradient.

    PubMed Central

    Pretlow, T G; Kreisberg, J I; Fine, W D; Zieman, G A; Brattain, M G; Pretlow, T P

    1978-01-01

    Mast-cell granules and polystyrene microspheres (0.600 and 1.011 micrometer in diameter) were sedimented in a previously described [Pretlow (1971) Anal. Biochem. 41, 248--255] isokinetic gradient in a low-speed centrifuge. For the analytical velocity sedimentation of organelles, this gradient offers several advantages over gradients that are commonly used for the sedimentation of organelles: (a) the density gradient (0.0008 g.ml-1.cm-1) is small, and the effective densities of organelles will change relatively little during sedimentation; (b) the densities at all points in the gradient (1.017--1.027 g/ml) are less than those in gradients commonly used for the sedimentation of organelles, the effective densities of sedimenting organelles are consequently relatively large, and the effect of density as a determinant of velocity of sedimentation is less limiting than in conventional gradients; (c) the small slope of the gradient is associated with a relatively slow increase in the viscosity encountered by the sedimenting organelle; (d) the iso-osmotic gradient is not significantly affected by the gradient medium (Ficoll), and the osmolarity can be adjusted to the desired value by the selection of an appropriate salt solution as the solvent for the Ficoll; (e) the gradient will be isokinetic for particles of densities similar to most organelles. An ultracentrifuge is not required for work with this gradient. Images Fig. 2. Fig. 3. Fig. 4. PMID:697757

  19. The Advantages of Normalizing Electromyography to Ballistic Rather than Isometric or Isokinetic Tasks.

    PubMed

    Suydam, Stephen M; Manal, Kurt; Buchanan, Thomas S

    2017-07-01

    Isometric tasks have been a standard for electromyography (EMG) normalization stemming from anatomic and physiologic stability observed during contraction. Ballistic dynamic tasks have the benefit of eliciting maximum EMG signals for normalization, despite having the potential for greater signal variability. It is the purpose of this study to compare maximum voluntary isometric contraction (MVIC) to nonisometric tasks with increasing degrees of extrinsic variability, ie, joint range of motion, velocity, rate of contraction, etc., to determine if the ballistic tasks, which elicit larger peak EMG signals, are more reliable than the constrained MVIC. Fifteen subjects performed MVIC, isokinetic, maximum countermovement jump, and sprint tasks while EMG was collected from 9 muscles in the quadriceps, hamstrings, and lower leg. The results revealed the unconstrained ballistic tasks were more reliable compared to the constrained MVIC and isokinetic tasks for all triceps surae muscles. The EMG from sprinting was more reliable than the constrained cases for both the hamstrings and vasti. The most reliable EMG signals occurred when the body was permitted its natural, unconstrained motion. These results suggest that EMG is best normalized using ballistic tasks to provide the greatest within-subject reliability, which beneficially yield maximum EMG values.

  20. Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise.

    PubMed

    Drescher, U; Mookerjee, S; Steegmanns, A; Knicker, A; Hoffmann, U

    2017-06-01

    To evaluate the effects of exercise velocity (60, 150, 240deg∙s(-1)) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO2) following high-intensity concentric-eccentric isokinetic exercise. Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t1/2) for oxygen uptake (V˙O2pulm), carbon dioxide output (V˙CO2pulm), and ventilation (V˙E). Significant differences of the t1/2 values were identified between 60 and 150deg∙s(-1). Significant differences in the t1/2 values were observed between V˙O2pulm and V˙CO2pulm and between V˙CO2pulm and V˙E. The time to attain the first avDO2-peak showed significant differences between arm and leg exercise. The present study illustrates, that V˙O2pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O2pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. The Effects of Kinesio Tape on Isokinetic Muscular Function of Horse Racing Jockeys

    PubMed Central

    Kim, Hyeyoung; Lee, Byounghee

    2013-01-01

    [Purpose] The purpose of this study was to conduct a scientific analysis of the effectiveness of Kinesio taping at preventing injury and improving horse racing jockey' performance, by studying the effects on isokinetic muscular function of Kinesio taping applied to the knee joint muscle. [Subjects] Eight horse racing jockeys were selected for this study. [Methods] Measurement of isokinetic muscular function of both flexor and extensor muscles was performed at the angular velocities of 60°/sec and 180°/sec using a Biodex system 3, before and after application of Kinesio taping to the rectus femoris, vastus medialis, vastus lateralis, and hamstring. [Result] At the angular velocities of 60°/sec and 180°/sec, significant differences were observed in both flexor and extensor peak torque, average power, and total work of the knee joint after application of Kinesio taping. [Conclusion] The application of Kinesio taping has a positive effect on the function of both knee flexors and extensors, and also kinetic ability. Therefore, its use would lead to a significant increase in the muscle function of horse racing jockeys. PMID:24259774

  2. 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.

  3. The fatigue effect of a simulated futsal match protocol on isokinetic knee torque production.

    PubMed

    Dal Pupo, Juliano; Detanico, Daniele; Santos, Saray Giovana Dos

    2014-11-01

    The objective of this study was to investigate the effects of a simulated futsal match protocol on isokinetic knee torque production. Twenty-one young futsal players participated in this study and performed a futsal-specific protocol comprising two blocks of 20-minute activities to simulate the match demands. At pre-protocol, half-time, and post-protocol, the concentric and eccentric isokinetic peak torque of the knee flexor and extensor muscles, the angle of peak torque, and the conventional and functional torque ratios were assessed. ANOVA was used to compare the variables (significance level p <  0.05). A decrease of knee flexor and extensor eccentric torque and knee flexor concentric torque was found, in which the pre-protocol levels were higher than those at half-time, with both being larger than those at post-protocol. The knee extensor concentric torque reduced at half-time. The angle of eccentric torque of knee flexors increased, and the conventional and functional torque ratios decreased at post-protocol. In conclusion, the protocol produced a time-dependent reduction of knee flexor and extensor torque in both concentric and eccentric actions. These findings suggested a possible impairment of performance and the emergence of risk factors for hamstring strains during a futsal match.

  4. 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.

  5. Anterior tibial translation during different isokinetic quadriceps torque in anterior cruciate ligament deficient and nonimpaired individuals.

    PubMed

    Kvist, J; Karlberg, C; Gerdle, B; Gillquist, J

    2001-01-01

    Factorial quasi-experimental design. To quantify the effect of different levels of isokinetic concentric and eccentric knee extensor torques on the anterior tibial translation in subjects with anterior cruciate ligament (ACL) deficiency. Electromyogram (EMG) activity of 4 leg muscles was recorded in order to detect any co-activation of extensors and flexors. The rehabilitation after an ACL injury is of importance for the functional outcome of the patient. In order to construct a rehabilitation program after that injury, it is important to understand the in vivo relationships between muscle force and tibial translation. Twelve patients with unilateral ACL injury and 11 uninjured volunteers performed 36 repetitions of a quadriceps contraction at different isokinetic concentric and eccentric torque levels, on a KinCom machine (60 degrees x s(-1)), with simultaneous recordings of tibial translation (CA-4000) and EMG activity from quadriceps and hamstrings muscles. Tibial translations and EMG levels were normalized to the maximum of each subject. The individual anterior tibial translation increased with increased quadriceps torque in a similar manner in both quadriceps contraction modes in all legs tested. During concentric mode, translation was similar in all groups, but during eccentric mode, the mean translation was 38% larger in the ACL injured knees. No quadriceps-hamstrings co-activation occurred in any test or group. An ACL deficient knee can limit the translation within a normal space during concentric muscle activity but not during eccentric activity. That limitation depends on other mechanisms than hamstrings co-activation.

  6. Isokinetic thigh muscle performance after long-term recovery from patellar dislocation.

    PubMed

    Mäenpää, H; Latvala, K; Lehto, M U

    2000-01-01

    Eighty-two patients (50 women, 32 men) underwent isokinetic muscle testing on average 13 years after a conservatively treated unilateral primary patellar dislocation. Three study groups were formed according to the natural history of recovery: group A (n = 32), patients with only primary conservative treatment; group B (n = 34) patients with conservative (group B1; n = 24) or surgical (group B2; n = 10) treatment of redislocations; group C (n = 16) patients with other residual complaints (anterior knee, pain subluxations) requiring surgery. The Cybex 6000 dynamometer system was used as the testing machine for quadriceps and hamstrings muscles, with proportional deficits of peak torque as the test parameter. Isokinetic testing revealed both quadriceps and hamstring muscle atrophy even after long-term recovery from injury. There were statistically significant differences between the three study groups at both tested speeds of quadriceps muscles (60 rad/s, P < 0.002; 180 rad/s, P < 0.009). Groups B1 and B2 presented similar results. The muscle performance findings are probably due to more than one factor: primary immobilization, poor outcome, patellofemoral degeneration, redislocations, and residual knee complaints followed by surgery and deficiency in motor control of thigh muscle had--together or separately--an effect on muscle performance.

  7. Reproducibility of isokinetic knee eccentric and concentric strength indices in asymptomatic young adults.

    PubMed

    Almosnino, Sivan; Stevenson, Joan M; Bardana, Davide D; Diaconescu, Elena D; Dvir, Zeevi

    2012-08-01

    To assess the reproducibility of isokinetic eccentric and concentric knee extension and flexion strength indices obtained at two different angular velocities. Cohort study. University human performance laboratory. 45 healthy physically active young adults (25 males). A non reciprocal protocol of concentric and eccentric contractions of the knee extensors and flexors was performed at 30 and 120°/s. Strength indices evaluated included peak moment; dynamic control ratios; and the difference between eccentric and concentric ratio at the two angular velocities. No evidence for inter-test bias in any of the strength indices was noted. Measurement precision for peak moment, as quantified using ratio limits of agreement, suggest that scores may be expected to vary up to 15% for the knee extensors in both eccentric and concentric contraction modes. An error of up to 19% was calculated for the peak moment scores of the knee flexors. Intraclass correlation coefficients revealed fairly robust preservation of participants' rank order for the majority of strength indices (>0.85). Isokinetic-related indices of knee muscles performance enable an acceptable level of detection of expected changes in muscular strength parameters as a result of planned interventions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Isokinetic muscle strength for ankle extensors and flexors: a comparison between elite sprint runners and swimmers.

    PubMed

    Ozçaldiran, B; Durmaz, B

    2008-09-01

    The aim of this study was to evaluate through isokinetic tests the muscular condition of ankles of elite sprint swimmers and elite sprint runners, and make comparisons within these groups. Fourteen elite swimmers and 8 elite runners were included in this cross-sectional study. The ankle extensors and flexors strength characteristics of elite sprinter athletes were tested at a slow (30 degrees/s) and a fast (120 degrees/s) speed using an isokinetic dynamometer. Subjects were assessed by one examiner on six separate days, within a 2-week period. A significant difference was noted between right and left sides for ankle joint flexors in runners at slow speed. Runners had higher left ankle flexion measures at 30 degrees/s and 120 degrees/s angular velocity than swimmers. There was no significant difference between the peak torques of the left and right sides at all angular velocities in swimmers. To our knowledge, this is the first study to assess the ankle flexors and extensors strength characteristics of elite sprinter swimmers making a comparison with elite sprinter runners. The findings presented in this study report the sport specific difference between the sprint swimmers and sprint runners. These values add a quantative dimension to rehabilitative and preventive sports medicine for elite sprinter runners and swimmers.

  9. The effects of kinesio tape on isokinetic muscular function of horse racing jockeys.

    PubMed

    Kim, Hyeyoung; Lee, Byounghee

    2013-10-01

    [Purpose] The purpose of this study was to conduct a scientific analysis of the effectiveness of Kinesio taping at preventing injury and improving horse racing jockey' performance, by studying the effects on isokinetic muscular function of Kinesio taping applied to the knee joint muscle. [Subjects] Eight horse racing jockeys were selected for this study. [Methods] Measurement of isokinetic muscular function of both flexor and extensor muscles was performed at the angular velocities of 60°/sec and 180°/sec using a Biodex system 3, before and after application of Kinesio taping to the rectus femoris, vastus medialis, vastus lateralis, and hamstring. [Result] At the angular velocities of 60°/sec and 180°/sec, significant differences were observed in both flexor and extensor peak torque, average power, and total work of the knee joint after application of Kinesio taping. [Conclusion] The application of Kinesio taping has a positive effect on the function of both knee flexors and extensors, and also kinetic ability. Therefore, its use would lead to a significant increase in the muscle function of horse racing jockeys.

  10. Comparison of isokinetic muscle strength and muscle power by types of warm-up

    PubMed Central

    Sim, Young-Je; Byun, Yong-Hyun; Yoo, Jaehyun

    2015-01-01

    [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. PMID:26157247

  11. Isokinetic Dynamometry and 1RM Tests Produce Conflicting Results for Assessing Alterations in Muscle Strength

    PubMed Central

    Del Vecchio, Fabricio Boscolo; Paoli, Antonio; Schoenfeld, Brad J; Bottaro, Martim

    2017-01-01

    Abstract The purpose of this study was to compare strength gains in the lower limbs, assessed by one maximum repetition (1RM) and isokinetic peak torque (PT), in young men undergoing a resistance training (RT) program. Twenty-seven young men performed resistance training twice a week for 11 weeks. Training involved two exercises for the lower body, two for the upper body and one for the midsection performed with three sets of 8-12 repetitions to momentary muscle failure. Before and after the training period, participants performed the 1RM test in the 45° leg press and knee extension PT in isokinetic dynamometry. The Pearson correlation coefficient was used to assess the relationship between the changes in 1RM and PT, and the Bland-Altman test was performed to check for agreement between the strength changes of both tests. There were significant changes in 1RM and PT of 23.98% and 15.96%, respectively (p < 0.05). The changes in leg press 1RM were significantly higher than the ones in PT. The Bland-Altman analysis revealed that the tests were not equivalent. In conclusion, professionals and researchers involved in strength assessment should be aware that the results obtained by PT and 1RM are not equivalent when evaluating individual responsiveness and/or the efficacy of an intervention on muscle strength, as the results obtained show large variations and can be even conflicting. PMID:28469740

  12. Isokinetic testing of evertor and invertor muscles in patients with chronic ankle instability.

    PubMed

    David, Pascal; Halimi, Mohamad; Mora, Isabelle; Doutrellot, Pierre-Louis; Petitjean, Michel

    2013-12-01

    Ankle sprains are among the most common sport-related injuries and can lead to chronic ankle instability. Impaired sensorimotor function of the ankle musculature is often suggested as a cause. The current study sought to assess and compare the isokinetic performance and electromyographic patterns of evertor and invertor muscles in patients with chronic ankle instability and in a control group. Twelve patients with chronic ankle instability and twelve healthy subjects were included. Isokinetic eccentric and concentric testing at various angular velocities was performed for eversion and inversion movements. The corresponding myoelectric activities of the fibularis longus and tibialis anterior muscles were quantified from surface electromyographic recordings by computing average root mean square values. Patients had lower myoelectric activity of the evertor and invertor muscles than controls did; this difference could account for the eccentric weakness associated with ankle instability. Functional strength ratios revealed a dynamic strength imbalance in unstable ankle patients and that may contribute to recurrent injury. Our findings suggest that rehabilitation programs for unstable ankle patients must be focused on the motor control of eccentric contractions of the ankle evertors and invertors, to boost these muscles' contribution to ankle stabilization.

  13. Isokinetic imbalance of hip muscles in soccer players with osteitis pubis.

    PubMed

    Mohammad, Walaa Sayed; Abdelraouf, Osama Ragaa; Elhafez, Salam Mohamed; Abdel-Aziem, Amr Almaz; Nassif, Nagui Sobhi

    2014-01-01

    In this study, we compared the isokinetic torques of hip flexors/extensors and abductors/adductors in soccer players suffering from osteitis pubis (OP), with normal soccer players. Twenty soccer male athletes with OP and 20 normal soccer athletes were included in this study. Peak torque/body weight (PT/BW) was recorded from hip flexor/extensor and abductor/adductor muscles during isokinetic concentric contraction modes at angular velocity of 2.1 rad · s(-1), for both groups. The results showed a significant difference between the normal and OP groups for hip flexors (P < 0.05). The normal group had significant, lower PT/BW value than the OP group for their hip flexors (P < 0.05). The hip flexor/extensor PT ratio of OP affected and non-affected limbs was significantly different from that of normal dominant and non-dominant limbs. There were no significant differences between the normal and OP groups for hip extensor, adductor and abductor muscles (P > 0.05). Regarding the hip adductor/abductor PT ratio, there was no significant difference between the normal and OP groups of athletes (P > 0.05). The OP group displayed increase in hip flexor strength that disturbed the hip flexor/extensor torque ratio of OP. Therefore, increasing the hip extensor strength should be part of rehabilitation programmes of patients with OP.

  14. Effects of a single whole body cryotherapy (-110°C) bout on neuromuscular performance of the elbow flexors during isokinetic exercise.

    PubMed

    Ferreira-Junior, J B; Vieira, C A; Soares, S R S; Guedes, R; Rocha Junior, V A; Simoes, H G; Brown, L E; Bottaro, M

    2014-12-01

    It has been demonstrated that body cooling may decrease neuromuscular performance. However, the effect of a single session of whole body cryotherapy (-110°C) on neuromuscular performance has not been well documented. Thus, the aim of this study was to evaluate the effects of a single exposure of WBC on elbow flexor neuromuscular performance. Thirteen physically active, healthy young men (age=27.9±4.2 years, mass=79.4±9.7 kg, height=176.7±5.2 cm) were randomly exposed to 2 different experimental conditions separated by a minimum of 72 h: 1) whole body cryotherapy- 3 min at -110°C; 2) control- 3 min at 21°C. All subjects were tested for maximal isokinetic elbow flexion at 60°.s(-1) 30 min before and 10 min after each condition. There were no significant differences in peak torque, average power, total work or muscle activity between conditions. Peak torque was lower at post-test compared to pre-test in both conditions (F=6.58, p=0.025). However, there were no differences between pre-test and post-test for any other variables. These results indicate that strength specialists, athletic trainers and physical therapists might utilize whole body cryotherapy before training or rehabilitation without compromising neuromuscular performance of the elbow flexors.

  15. Inter-machine reliability of the Biodex and Cybex isokinetic dynamometers for knee flexor/extensor isometric, concentric and eccentric tests.

    PubMed

    de Araujo Ribeiro Alvares, João Breno; Rodrigues, Rodrigo; de Azevedo Franke, Rodrigo; da Silva, Bruna Gonçalves Cordeiro; Pinto, Ronei Silveira; Vaz, Marco Aurélio; Baroni, Bruno Manfredini

    2015-02-01

    To assess the inter-machine reliability of the Biodex System 3 Pro and Cybex Humac Norm Model 770 dynamometers for knee extensor and knee flexor peak torque measurements in isometric, concentric and eccentric tests. Randomized/crossover. Exercise Research Laboratory, Federal University of Rio Grande do Sul (Brazil). 25 healthy male subjects. Isometric, concentric and eccentric knee extensor and knee flexor peak torques recorded in the same test procedure performed on both isokinetic dynamometers. One-way ANOVA, intraclass correlation coefficient (ICC), standard error of measurement (SEM) and coefficient of variation (CV) were used to verify significant differences, relative and absolute reliability between devices. No significant differences were found between tests performed on Biodex and Cybex (p > 0.05). ICC values indicated a high to very high reproducibility for isometric, concentric and eccentric peak torques (0.88-0.92), and moderate to high reliability for agonist-antagonist strength ratios (0.62-0.73). Peak torque did not show great difference between dynamometers for SEM (3.72-11.27 Nm) and CV (5.27-7.77%). Strength ratios presented CV values of 8.57-10.72%. Maximal knee extensor and knee flexor tests performed in isometric (60° of knee flexion), concentric and eccentric modes at 60°/s in Biodex and Cybex dynamometers present similar values. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Oxygen uptake in maximal effort constant rate and interval running.

    PubMed

    Pratt, Daniel; O'Brien, Brendan J; Clark, Bradley

    2013-01-01

    This study investigated differences in average VO2 of maximal effort interval running to maximal effort constant rate running at lactate threshold matched for time. The average VO2 and distance covered of 10 recreational male runners (VO2max: 4158 ± 390 mL · min(-1)) were compared between a maximal effort constant-rate run at lactate threshold (CRLT), a maximal effort interval run (INT) consisting of 2 min at VO2max speed with 2 minutes at 50% of VO2 repeated 5 times, and a run at the average speed sustained during the interval run (CR submax). Data are presented as mean and 95% confidence intervals. The average VO2 for INT, 3451 (3269-3633) mL · min(-1), 83% VO2max, was not significantly different to CRLT, 3464 (3285-3643) mL · min(-1), 84% VO2max, but both were significantly higher than CR sub-max, 3464 (3285-3643) mL · min(-1), 76% VO2max. The distance covered was significantly greater in CLRT, 4431 (4202-3731) metres, compared to INT and CR sub-max, 4070 (3831-4309) metres. The novel finding was that a 20-minute maximal effort constant rate run uses similar amounts of oxygen as a 20-minute maximal effort interval run despite the greater distance covered in the maximal effort constant-rate run.

  17. A Repeat Look at Repeating Patterns

    ERIC Educational Resources Information Center

    Markworth, Kimberly A.

    2016-01-01

    A "repeating pattern" is a cyclical repetition of an identifiable core. Children in the primary grades usually begin pattern work with fairly simple patterns, such as AB, ABC, or ABB patterns. The unique letters represent unique elements, whereas the sequence of letters represents the core that is repeated. Based on color, shape,…

  18. Efficacy of kinesio taping on isokinetic quadriceps torque in knee osteoarthritis: a double blinded randomized controlled study.

    PubMed

    Anandkumar, Sudarshan; Sudarshan, Shobhalakshmi; Nagpal, Pratima

    2014-08-01

    Double blind pre-test post-test control group design. To compare the isokinetic quadriceps torque, standardized stair-climbing task (SSCT) and pain during SSCT between subjects diagnosed with knee osteoarthritis pre and post kinesio tape (KT) application with and without tension. Strength of the quadriceps and torque producing capability is frequently found to be compromised in knee osteoarthritis. The efficacy of KT in improving isokinetic quadriceps torque in knee osteoarthritis is unknown, forming the basis for this study. Forty subjects were randomly allocated to either the experimental (therapeutic KT with tension) or control group (sham KT without tension) with the allocation being concealed. Pre and post test measurements of isokinetic quadriceps torque, SSCT and pain during SSCT were carried out by a blinded assessor. A large effect size with significant improvements in the peak quadriceps torque (concentric and eccentric at angular velocities of 90° per second and 120° per second), SSCT and pain were obtained in the experimental group when compared to the control group. Application of therapeutic KT is effective in improving isokinetic quadriceps torque, SSCT and reducing pain in knee osteoarthritis.

  19. 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.

  20. Multiple time scale molecular dynamics for fluids with orientational degrees of freedom. II. Canonical and isokinetic ensembles

    NASA Astrophysics Data System (ADS)

    Omelyan, Igor P.; Kovalenko, Andriy

    2011-12-01

    We have developed several multiple time stepping techniques to overcome the limitations on efficiency of molecular dynamics simulations of complex fluids. They include the modified canonical and isokinetic schemes, as well as the extended isokinetic Nosé-Hoover chain approach. The latter generalizes the method of Minary, Tuckerman, and Martyna for translational motion [Phys. Rev. Lett. 93, 150201 (2004)], 10.1103/PhysRevLett.93.150201 to systems with both translational and orientational degrees of freedom. Although the microcanonical integrators are restricted to relatively small outer time steps of order of 16 fs, we show on the basis of molecular dynamics simulations of ambient water that in the canonical and isokinetic thermostats the size of these steps can be increased to 50 and 75 fs, respectively (at the same inner time step of 4 fs). Within the generalized isokinetic Nosé-Hoover chain algorithm we have derived, huge outer time steps of order of 500 fs can be used without losing numerical stability and affecting equilibrium properties

  1. Associations of isokinetic and isotonic knee strength with knee function and activity level after anterior cruciate ligament reconstruction: a prospective cohort study.

    PubMed

    Pua, Yong-Hao; Ho, Jia-Ying; Chan, Suelyn Ai-Sim; Khoo, Shin-Jiun; Chong, Hwei-Chi

    2017-07-21

    Although isokinetic dynamometry often serves as a reference to assess the concurrent validity of weight-machine isotonic strength testing, it is unknown whether isokinetic knee strength is associated with knee function and activity level more strongly than isotonic knee strength in patients with an anterior cruciate ligament reconstruction (ACLR). This study aimed to compare the associations of isokinetic and isotonic knee strength with knee function and work-and-sports activity levels in patients with ACLR. One-hundred and six patients with a unilateral ACLR participated. At three months post-ACLR, isokinetic quadriceps and hamstrings strength was measured using an isokinetic dynamometer whilst isotonic strength was measured using weight machines. At six months post-ACLR, patients performed the single-leg hop-for-distance test. Self reported knee function and work-and-sports activity levels were assessed by the Lysholm Knee Score and Tegner Activity Score, respectively. In multivariable analyses, isotonic and isokinetic quadriceps strength limb symmetry indices (LSIs) were significantly associated with all outcomes (P≤0.03) and had comparable predictive performance. Isotonic and isokinetic hamstrings strength LSIs were significantly associated with Lysholm scores (P≤0.03) and isotonic hamstrings strength was additionally significantly associated with hop-for-distance LSI (P=0.01). Weight machine-derived isotonic quadriceps strength was independently and consistently associated with knee function and work-and-sport activity level post-ACLR. Isokinetic knee strength was not more strongly associated than isotonic knee strength with the various outcomes. These findings have logistic and economic implications because the isokinetic dynamometer system is relatively expensive and its operation requires more logistic effort and technical skills. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Creatine supplementation attenuates hemodynamic and arterial stiffness responses following an acute bout of isokinetic exercise.

    PubMed

    Sanchez-Gonzalez, Marcos A; Wieder, Ralph; Kim, Jeong-Su; Vicil, Florence; Figueroa, Arturo

    2011-09-01

    Arterial stiffness and hemodynamics may be increased following a bout of resistance exercise. Oral creatine supplementation (Cr) may attenuate cardiovascular responses after exercise via improved anaerobic metabolism. This study was aimed to determine the effect of Cr on hemodynamic and arterial stiffness responses after acute isokinetic exercise. Sixteen healthy males (22.6 ± 0.6 year) were randomly assigned to either placebo (Pl, n = 8) or Cr (n = 8) (2 × 5 g/day) for 3 weeks. Brachial systolic blood pressure (SBP), heart rate (HR), brachial-ankle pulse wave velocity (baPWV), and leg PWV were measured in the supine position at rest before and after the interventions. After the supplementation period, parameters were also measured 5 min (PE5) and 15 min (PE15) after two sets of leg isokinetic exercise. There was no difference between the groups in resting measurements before and after the supplementation. Compared with the Pl group, the Cr group had attenuated (P < 0.05) increases in SBP at PE5 (Pl 14.0 ± 2.5, Cr 5.6 ± 2.3 mmHg), HR at both P5 (Pl 28 ± 4 vs. Cr 16 ± 2 beats/min) and PE15 (Pl 21 ± 3, Cr 11 ± 2 beats/min) and rate pressure product at P5 (Pl 45.8 ± 6.4, Cr 24.8 ± 2.2) and P15 (Pl 34.2 ± 5.0, Cr 15.9 ± 6.0). Compared with the Pl group, the Cr group had suppressed increases in baPWV at PE5 (Pl 1.5 ± 0.4, Cr -0.1 ± 0.4 m/s) and PE15 (Pl 1.1 ± 0.2, Cr -0.3 ± 0.3 m/s) and returned SBP to pre-exercise values at PE15 (Pl 10.6 ± 2.8, Cr 2.1 ± 2.6 mmHg). PWV in the exercised leg decreased at PE5 in both groups. These findings suggest that Cr supplementation attenuates the hemodynamic and baPWV responses after acute isokinetic exercise.

  3. FACTORS WHICH CONTROL MAXIMAL GROWTH OF BACTERIA

    PubMed Central

    Sinclair, N. A.; Stokes, J. L.

    1962-01-01

    Sinclair, N. A. (Washington State University, Pullman) and J. L. Stokes. Factors which control maximal growth of bacteria. J. Bacteriol. 83:1147–1154. 1962.—In a chemically defined medium containing 1% glucose and 0.1% (NH4)2SO4, both of these compounds are virtually exhausted by the growth of Pseudomonas fluorescens. If these carbon, energy, and nitrogen sources are added back to the culture filtrate, maximal growth to the level of the original culture is obtained. This process can be repeated several times with the same results. Eventually, however, the supply of minerals in the culture limits growth. When the nutrient levels are raised to 3% glucose and 0.3% (NH4)2SO4, lack of oxygen and low pH limit growth before the supply of nutrients is exhausted. There is no evidence that specific autoinhibitory substances are produced either in chemically defined or complex nitrogenous media or that physical crowding of the cells limits growth. The results with Escherichia coli are similar to those with P. fluorescens. However, after a few growth cycles aerobically and after only one growth cycle anaerobically, inhibitory substances, probably organic acids, accumulate and limit growth. PMID:13913264

  4. [Consequences and prediction of hamstring muscle injury with concentric and eccentric isokinetic parameters in elite soccer players].

    PubMed

    Dauty, M; Potiron-Josse, M; Rochcongar, P

    2003-12-01

    To know if isokinetic parameters identify previous hamstring (H) injury and predict a new muscle injury in high-level soccer player. Concentric (con) and eccentric (ecc) isokinetic torque was measured at the angular speed of 60 degrees /s in 28 elite soccer players (23 years +/- 3.3; 74 kg +/- 7.5; 178 cm +/- 6.5). First, 11 players, victims of 15 moderate or major hamstring injuries in the preceding 2 years, were compared with 17 players without previous hamstring injury. Comparisons were carried out from isokinetic knee flexors-extensors ratios [Hcon/Qcon and Hecc/Qcon] and bilateral knee flexors ratios [Hcon/Hcon and Hecc/Hecc]. Secondly, all the population was followed during 12 months and the isokinetic muscular profile of players who presented a recurrence or a new hamstring muscle injury was analysed. A concentric ratio hamstring-to-quadriceps lower than 0.6 and a hamstring asymmetry of more than 10% do not allow to identify previous hamstring injury. On the other hand, the mixed ratio eccentric hamstring-to-concentric quadriceps lower than 0.6 represents the best indicator (probability: 77.5%). The rate of recurrence is 30% (three cases of 10) and the rate of new hamstring muscle injury is 31% (five cases of 16) (P > 0.05). One of the five injured soccer players presented a concentric ratio hamstring-to-quadriceps lower than 0.6 and no player presented a mixed ratio lower than 0.6. However, four of the five injured players presented a concentric and an eccentric asymmetry. But, it is the strongest side, which presented a new hamstring muscle injury. The mixed ratio eccentric hamstring-to-concentric quadriceps lower than 0.6 identify a previous hamstring injury despite the resumption of competitive soccer. However, this ratio and the others isokinetic studied parameters do not predict a recurrence or a new hamstring muscle injury.

  5. Effects of Two Warm-up Programs on Balance and Isokinetic Strength in Male High School Soccer Players.

    PubMed

    Ghareeb, Dana M; McLaine, Alice J; Wojcik, Janet R; Boyd, Joni M

    2017-02-01

    Ghareeb, DM, McLaine, AJ, Wojcik, JR, and Boyd, JM. Effects of two warm-up programs on balance and isokinetic strength in male high school soccer players. J Strength Cond Res 31(2): 372-379, 2017-One of the most common warm-up programs used to prevent injury in soccer, FIFA11+, integrates aerobic, strength, and balance. The purpose of this study was to compare FIFA11+ to a new warm-up program (NWP) on balance and isokinetic strength of the quadriceps and hamstrings at 60, 180, and 300°·s in male high school soccer players. Participants at one school (n = 17) performed the NWP before practice for 6 weeks during one soccer season, whereas participants at another school (n = 17) performed FIFA11+. There were no differences at baseline. At posttest, players in NWP significantly improved (p < 0.01) in Overall Stability Index Balance, Anterior/Posterior Index Balance, and Medial Lateral Index with large effect sizes (ES) > 1.3. No changes were seen in FIFA11+. Isokinetic strength peak torque increased at 60°·s in the quadriceps and hamstrings in dominant and nondominant legs in NWP (p < 0.01, ES, 0.59-1.02) and in hamstrings in FIFA11+ (p ≤ 0.05, ES, 0.32-0.40). At 180°·s, NWP improved peak torque (p < 0.01, ES, 0.74-0.90) except hamstrings in the nondominant leg, whereas FIFA11+ showed improvements across all muscle groups (p < 0.01), but with smaller ES, 0.25-0.84. Both programs improved isokinetic peak torque at 300°·s except hamstrings in the nondominant leg in NWP, although ES were higher in NWP (ES, 0.60-1.03) than FIFA11+ (ES, 0.31-0.42). The NWP seems to be effective for soccer conditioning by improving balance and isokinetic strength.

  6. Isometric and isokinetic muscle strength in the upper extremity can be reliably measured in persons with chronic stroke.

    PubMed

    Ekstrand, Elisabeth; Lexell, Jan; Brogårdh, Christina

    2015-09-01

    To evaluate the test-retest reliability of isometric and isokinetic muscle strength measurements in the upper extremity after stroke. A test-retest design. Forty-five persons with mild to moderate paresis in the upper extremity > 6 months post-stroke. Isometric arm strength (shoulder abduction, elbow flexion), isokinetic arm strength (elbow extension/flexion) and isometric grip strength were measured with electronic dynamometers. Reliability was evaluated with intra-class correlation coefficients (ICC), changes in the mean, standard error of measurements (SEM) and smallest real differences (SRD). Reliability was high (ICCs: 0.92-0.97). The absolute and relative (%) SEM ranged from 2.7 Nm (5.6%) to 3.0 Nm (9.4%) for isometric arm strength, 2.6 Nm (7.4%) to 2.9 Nm (12.6%) for isokinetic arm strength, and 22.3 N (7.6%) to 26.4 N (9.2%) for grip strength. The absolute and relative (%) SRD ranged from 7.5 Nm (15.5%) to 8.4 Nm (26.1%) for isometric arm strength, 7.1 Nm (20.6%) to 8.0 Nm (34.8%) for isokinetic arm strength, and 61.8 N (21.0%) to 73.3 N (25.6%) for grip strength. Muscle strength in the upper extremity can be reliably measured in persons with chronic stroke. Isometric measurements yield smaller measurement errors than isokinetic measurements and might be preferred, but the choice depends on the research question.

  7. Absolute and relative reliability of isokinetic and isometric trunk strength testing using the IsoMed-2000 dynamometer.

    PubMed

    Roth, Ralf; Donath, Lars; Kurz, Eduard; Zahner, Lukas; Faude, Oliver

    2017-03-01

    The present study aimed to assess the between day reliability of isokinetic and isometric peak torque (PT) during trunk measurement on an isokinetic device (IsoMed 2000). Test-retest-protocol on five separate days. Fifteen healthy sport students (8 female and 7 male) aged 21 to 26. PT was assessed in isometric back extension and flexion as well as right and left rotation. Isokinetic strength was captured at a speed of 60°/s and 150°/s for all tasks. For none of the assessed parameters a meaningful variation in PT during test days was observed. Relative reliability (ICC = 0.85-0.96) was excellent for all tasks. Estimates of absolute reliability as Coefficient of Variation (CoV) and Standard Error of Measurement (SEM in Nm/kg lean body mass) remained stable for isometric (6.9% < CoV < 9.4%; 0.15 < SEM < 0.23) and isokinetic mode (60°/s: 3.7% < CoV < 8.6%; 0.08 < SEM < 0.24; 150°/s: 6.9% < CoV < 12.4%; 0.10 < SEM < 0.31). In contrast, reliability between familiarization day and day 1 was lower (6.6% < CoV < 26.2%; 0.10 < SEM < 0.65). Trunk strength measurement in flexion and extension or trunk rotation in either isometric or isokinetic condition is highly reliable. Therefore, it seems possible to elucidate changes which are smaller than 10% due to intervention programs when a preceding familiarization condition was applied. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Position sense and reaction angle after eccentric exercise: the repeated bout effect.

    PubMed

    Paschalis, V; Nikolaidis, M G; Giakas, G; Jamurtas, A Z; Owolabi, E O; Koutedakis, Y

    2008-05-01

    The purpose of the present investigation was to examine the effects of a repeated eccentric exercise on position sense and muscle reaction angle. Fourteen healthy women underwent an isokinetic exercise session on their knee flexors, which was repeated after 4 weeks. Muscle damage indices, position sense and joint reaction angle of the knee were examined before, immediately after, as well as at 1, 2, 3, 4 and 7 days after exercise. The second exercise bout induced significantly lesser effects in all muscle damage indices as well as lesser disturbances in position sense and reaction angle when compared to the first one. The main finding of this study is that position sense and joint reaction angle to release of the lower limbs may adapt in response to a repeated bout of eccentric exercise, leading to less disturbances in position sense and reaction angle after the second bout of exercise.

  9. Similar increases in muscle size and strength in young men after training with maximal shortening or lengthening contractions when matched for total work.

    PubMed

    Moore, Daniel R; Young, Mark; Phillips, Stuart M

    2012-04-01

    Training exclusively with eccentric (lengthening) contractions can result in greater muscular adaptations than training with concentric (shortening) contractions. We aimed to determine whether training-induced increases in muscle size and strength differed between muscles performing maximal lengthening (LC) or maximal shortening (SC) contractions when total external work is equivalent. Nine healthy young males completed a 9-week isokinetic (0.79 rad/s) resistance training program of the elbow flexors whereby they performed LC with one arm and an equivalent volume of total external work with the contralateral arm as SC. Training increased isometric peak torque for both LC (~10%) and SC (~20%) with no difference (P = 0.14) between conditions. There were also similar increases in isokinetic peak torque at both slow (0.79 rad/s) and fast (5.24 rad/s) shortening and lengthening peak torque for both LC (~8-10%) and SC (~9-20%). Training increased work per repetition similarly for both LC (~17%) and SC (~22%), in spite of ~40% greater work per repetition with LC. The increase in muscle cross-sectional area with training was also similar (P = 0.37) between LC (~6.5%) and SC (~4.6%). We conclude that increases in muscle size and strength with short-term unilateral resistance training are unrelated to muscle contraction type when matched for both exercise intensity (i.e. maximal contractions) and total external work.

  10. Force steadiness, muscle activity, and maximal muscle strength in subjects with subacromial impingement syndrome.

    PubMed

    Bandholm, Thomas; Rasmussen, Lars; Aagaard, Per; Jensen, Bente Rona; Diederichsen, Louise

    2006-11-01

    We investigated the effects of the subacromial impingement syndrome (SIS) on shoulder sensory-motor control and maximal shoulder muscle strength. It was hypothesized that both would be impaired due to chronic shoulder pain associated with the syndrome. Nine subjects with unilateral SIS who remained physically active in spite of shoulder pain and nine healthy matched controls were examined to determine isometric and isokinetic submaximal shoulder-abduction force steadiness at target forces corresponding to 20%, 27.5%, and 35% of the maximal shoulder abductor torque, and maximal shoulder muscle strength (MVC). Electromyographic (EMG) activity was assessed using surface and intramuscular recordings from eight shoulder muscles. Force steadiness was impaired in SIS subjects during concentric contractions at the highest target force level only, with muscle activity largely unaffected. No between-group differences in shoulder MVC were observed. The present data suggest that shoulder sensory-motor control is only mildly impaired in subjects with SIS who are able to continue with upper body physical activity in spite of shoulder pain. Thus, physical activity should be continued by patients with SIS, if possible, to avoid the loss in neural and muscle functions associated with inactivity.

  11. Impairment on cardiovascular and autonomic adjustments to maximal isometric exercise tests in offspring of hypertensive parents.

    PubMed

    Francica, Juliana V; Heeren, Marcelo V; Tubaldini, Márcio; Sartori, Michelle; Mostarda, Cristiano; Araujo, Rubens C; Irigoyen, Maria-Cláudia; De Angelis, Kátia

    2013-06-01

    The objective of the present study was to compare cardiovascular and autonomic responses to a mental stress test and to a maximal isometric exercise test between offspring of normotensive (ON, n = 10) and hypertensive parents (OH, n = 10). Subjects underwent a 3-min Stroop Color Word Test and a maximal isometric exercise test performed in an isokinetic dynamometer with continuous RR interval monitoring. At rest, arterial pressure and heart rate were similar between groups, but there was a significant reduction in total RR interval variance (ON: 5933 ± 493 vs. OH: 2967 ± 390 ms(2)) and an increase in low-high frequency components ratio of heart rate variability (ON: 2.3 ± 0.4 vs. OH: 4.6 ± 0.8) in OH group. In the first minute of the mental stress test and after both tests, the OH group presented increased heart rate as compared with the ON group. After both tests, only the ON group presented an increase in sympathetic component, thus reaching resting values similar to those of the OH group. Our data demonstrated increased resting cardiac sympathetic modulation in offspring of hypertensive parents at similar levels to that observed in offspring of normotensive parents after a mental stress test or a maximal isometric exercise test. Additionally, the exacerbated heart rate responses to these physiological tests in OH subjects may be associated with resting autonomic dysfunction, thus reinforcing these evaluations as important tools for detecting early dysfunctions in this genetically predisposed population.

  12. Effect of Stochastic Modulation of Inter-Pulse Interval During Stimulated Isokinetic Leg Extension

    PubMed Central

    Aksöz, Efe Anil; Laubacher, Marco; Binder-Macleod, Stuart; Hunt, Kenneth J.

    2016-01-01

    Recumbent cycling exercise achieved by functional electrical stimulation (FES) of the paralyzed leg muscles is effective for cardiopulmonary and musculoskeletal conditioning after spinal cord injury, but its full potential has not yet been realized. Mechanical power output and efficiency is very low and endurance is limited due to early onset of muscle fatigue. The aim of this work was to compare stochastic modulation of the inter-pulse interval (IPI) to constant-frequency stimulation during an isokinetic leg extension task similar to FES-cycling. Seven able-bodied subjects participated: both quadriceps muscles were stimulated (n = 14) with two activation patterns (P1-constant frequency, P2-stochastic IPI). There was significantly higher power output with P2 during the first 30 s (p = 0.0092), the last 30 s (p = 0.018) and overall (p = 0.0057), but there was no overall effect on fatiguability when stimulation frequency was randomly modulated. PMID:27990242

  13. Biomechanical assessment of the effects of significant hamstring injury: an isokinetic study.

    PubMed

    Paton, R W; Grimshaw, P; McGregor, J; Noble, J

    1989-05-01

    Soccer players may develop recurrent hamstring injuries. This may be due to inadequate rehabilitation or to recurrent injury. In addition, following injury, the hamstring muscular complex may be permanently damaged, resulting in decreased strength, and increased likelihood of recurrent injury. Fourteen professional soccer players were assessed by clinical examination and by isokinetic testing with a Cybex II machine. Seven had suffered moderate or major hamstring injuries in the past year. There were seven controls. None of the hamstring group were currently suffering from an acute hamstring injury. The results of the two groups were compared. There were no differences in the mean results. This pilot study suggests that no permanent functional damage occurs to the muscular complex after moderate or major hamstring injuries after correct treatment. However, further research is required to confirm this.

  14. Orthostatic responses following 30-day bed rest deconditioning with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Wade, C. E.; Leftheriotis, G.

    1989-01-01

    The effects of intensive exercise training on tilt tolerance following deconditioning of astronauts were investigated by studying orthostatic responses of 19 subjects who underwent two intensive exercise-training regimens during 30 days of -6-deg head-down bed rest (BR). Subjects were divided into no-exercise control group, and two exercise groups, one performing isotonic (Quinton ergometer) exercises, the other doing isokinetic (Lido ergometer) exercises. A 60-deg head-up tilt test was administered on the control day 1 and BR day 30; the test was terminated at 60 min or when presyncopal signs and/or symptoms occurred. It was found that exercise training did not affect tilt tolerance significantly.

  15. Limitations to maximal oxygen uptake.

    PubMed

    Sutton, J R

    1992-02-01

    An increase in exercise capacity depends on the magnitude of increase in maximum aerobic capacity. Central and peripheral factors may limit oxygen uptake. Central oxygen delivery depends on cardiac output and maximal arterial oxygen content. Peripheral extraction of the delivered oxygen is expressed as a-v O2. With increasing intensities of exercise, the respiratory system may become limiting in some trained individuals. Most studies have shown a higher stroke volume in maximal as well as submaximal exercise in the trained vs untrained individuals. A variety of peripheral factors determine vascular tone. Maximal oxygen uptake depends on all components of the oxygen transporting system, but stroke volume appears to be the prime determinant in the trained subject. At maximum exercise the capacity of the muscle capillary network is never reached.

  16. Is the subscapularis normal after the open Latarjet procedure? An isokinetic and magnetic resonance imaging evaluation.

    PubMed

    Caubère, Alexandre; Lami, Damien; Boileau, Pascal; Parratte, Sébastien; Ollivier, Matthieu; Argenson, Jean-Noël

    2017-10-01

    The Latarjet procedure is considered to be a violation of the subscapularis muscle. This study evaluated the postoperative status of the subscapularis through isokinetic and magnetic resonance imaging analysis after splitting. We hypothesized that compared with a healthy contralateral shoulder, there would be satisfactory recovery of subscapularis strength at the cost of some fatigability and some mild fatty infiltration. This was a case-control retrospective study of patients who underwent a Latarjet procedure between January 2013 and January 2015. A total of 20 patients were reviewed at 1 year postoperatively. With the patient seated, strength testing of both shoulders was done (concentric, eccentric, and fatigability) with a dynamometer. Trophicity and fatty infiltration were analyzed by magnetic resonance imaging. Strength of the internal rotators (IRs) and external rotators (ERs) of the injured shoulder was significantly lower compared with the healthy shoulder in concentric testing at 180°/s and 60°/s (13% for IR and 20% for E, P < .05) and in eccentric testing at 60°/s (19% for IR and 16% for ER, P < .05). A peak torque ratio (ER/IR) of the operated-on shoulder was maintained. The difference in muscular endurance was significant (P < .001). There was no muscle atrophy and minimal or no fatty infiltration of the subscapularis in any patient. At 1 year after the open Latarjet procedure, isokinetic testing showed a combined strength deficit in both internal and external rotation with a conserved muscle balance. Although no significant subscapularis fatty infiltration or atrophy was noted, there was a significant deficit in endurance compared with the healthy shoulder. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  17. An isokinetic eccentric programme for the management of chronic lateral epicondylar tendinopathy

    PubMed Central

    Croisier, Jean‐Louis; Foidart‐Dessalle, Marguerite; Tinant, France; Crielaard, Jean‐Michel; Forthomme, Bénédicte

    2007-01-01

    Background Lateral epicondylitis represents a frequent overuse injury. In spite of many conservative treatment procedures, prolonged symptoms and relapse are frequently observed. Objective To compare the outcome of patients performing an isokinetic eccentric training with that of age‐, gender‐, activity‐matched patients receiving a non‐strengthening classical rehabilitation. Methods Ninety‐two patients with unilateral chronic lateral epicondylar tendinopathy (mean duration of symptoms 8±3 months) were assigned either to a control group (n = 46) or to an eccentrically trained group (n = 46). The control group underwent a passive standardised rehabilitation programme that excluded strengthening exercises. In addition to this programme, the trained group also performed eccentric exercises based on the repetitive lengthening of the active musculo‐tendinous unit. The latter exercises started with submaximal contraction intensity and slow speed movement. Modalities were progressively intensified (increase in intensity contraction and speed movement) over a long priod of treatment. Programme effectiveness was assessed through pain score evaluation, a disability questionnaire, muscle strength measurement and ultrasonographic examination. Results Compared to the non‐strengthening control group, the following observations were made in the eccentrically trained group: (1) a significantly more marked reduction of pain intensity, mainly after one month of treatment; (2) an absence of strength deficit on the involved side through bilateral comparison for the forearm supinator and wrist extensor muscles; (3) an improvement of the tendon image as demonstrated by decreasing thickness and a recovered homogenous tendon structure; and (4) a more marked improvement in disability status during occupational, spare time and sports activities. Conclusion These results highlight the relevance of implementing isokinetic adapted eccentric training in the management of

  18. [Isokinetic torque of quadriceps in patients with untreated anterior cruciate ligament injury of the knee joint].

    PubMed

    Ikeda, H

    1993-09-01

    In order to study the role of muscle strength in patients with untreated anterior cruciate ligament (ACL) injury of the knee joint, the torque of the quadriceps was isokinetically measured during concentric contraction (CC) and passive eccentric contraction (PEC). The results were compared with those in normal individuals and sports players. Ninety patients with untreated ACL injury were subjected for the study. There were 50 men and 40 women. The normal group consisted of 20 students and the sports player group consisted of 20 soccer players. The peak torque and the torque at 30 degrees flexion of the quadriceps were isokinetically measured during CC and PEC by using a BIODEX machine. In patients with ACL injury, the peak torque was smaller in the injured side as compared with the uninjured side. At the same angle velocity, decrease of PEC in the injured side was larger than that of CC. These results were compared with the normal group and the sports player group. There was significant difference in the peak torque per body weight among each groups. But, the torque per body weight at 30 degrees flexion was almost consistent in these three groups. A considerable quadriceps atrophy occurs following ACL injury. In our experience, patients with functional absence of ACL are much more difficult to return to vigorous sports which require explosive eccentric contraction than to return to endurance sports which require repetitive concentric contractile efforts of the quadriceps. In the present study, decrease of the passive eccentric contraction in the injured side was more pronounced than that of the concentric contraction. From these results, the significantly decreased passive eccentric torque in the patients with untreated ACL injury can be a factor to cause instability of the knee joint in active daily life as well as in sports activities.

  19. Isokinetic muscle strength of the trunk and bilateral knees in young subjects with lumbar disc herniation.

    PubMed

    Ho, Cheng-Wen; Chen, Liang-Cheng; Hsu, Hsian-He; Chiang, Shang-Lin; Li, Min-Hui; Jiang, Shuu-Hai; Tsai, Kao-Chung

    2005-09-15

    Cross-sectional study comparing normal subjects and patients with lumbar disc herniation. To evaluate trunk and knee muscle strength in patients with L4-L5 and/or L5-S1 disc herniation. Numerous studies have shown that patients with low back pain have weaker trunk muscles. The strength of trunk and knee muscles has not been investigated simultaneously in patients with lumbar disc herniation. Forty-one controls and 2 patients were included. Isokinetic strength of the trunk and bilateral knees was tested on a calibrated isokinetic testing machine (Biodex System 3 Pro) regardless of the laterality of the radiculopathy. The testing was carrying out at two different velocities: 60 degrees and 120 degrees per second. Total trunk strength and knee strength were significantly lower in these patients (4.34 +/- 1.06 and 4.06 +/- 1.16 vs. 6.21 +/- 1.05 and 5.83 +/- 1.09 Nm/kg at 60 degrees and 120 degrees per second, respectively, P < 0.001). In patients with unilateral sciatica, there was no significant difference (P > 0.05) in unilateral knee strength between sciatica-involved and -uninvolved limbs (1.89 +/- 0.5, 1.08 +/- 0.45, 1.48 +/- 0.58, 0.93 +/- 0.41 vs. 1.68 +/- 0.45, 0.91 +/- 0.38, 1.41 +/- 0.48, 0.79 +/- 0.39 Nm/kg in sciatica-uninvolved vs. sciatica-involved limbs during extension and flexion at 60 degrees and 120 degrees per second, respectively). Total trunk strength was significantly correlated with total knee strength in both groups. In the patients with lumbar disc herniation, muscle strength of the trunk and knees was decreased to a similar extent. Weaker knee strength was found on either side of the lower extremity in the patients with unilateral sciatica, regardless of its location.

  20. Effects of photobiomodulation on the fatigue level in elderly women: an isokinetic dynamometry evaluation.

    PubMed

    Vassão, P G; Toma, R L; Antunes, H K M; Tucci, H T; Renno, A C M

    2016-02-01

    Aging is responsible by a series of morphological and functional modifications that lead to a decline of muscle function, particularly in females. Muscle tissue in elderly people is more susceptible to fatigue and, consequently, to an increased inability to maintain strength and motor control. In this context, therapeutic approaches able of attenuating muscle fatigue have been investigated. Among these, the photobiomodulation demonstrate positive results to interacts with biological tissues, promoting the increase in cell energy production. Thus, the aim of this study was to investigate the effects of photobiomodulation (808 nm, 250 J/cm(2), 100 mW, 7 J each point) in the fatigue level and muscle performance in elderly women. Thirty subjects entered a crossover randomized double-blinded placebo-controlled trial. Photobiomodulation was delivered on the rectus femoris muscle of the dominant limb immediately before the fatigue protocol. In both sessions, peripheral muscle fatigue was analyzed by surface electromyography (EMG) and blood lactate analysis. Muscle performance was evaluated using an isokinetic dynamometer. The results showed that photobiomodulation was able of reducing muscle fatigue by a significant increase of electromyographic fatigue index (EFI) (p = 0.047) and decreasing significantly lactate concentration 6 min after the performance of the fatigue protocol (p = 0. 0006) compared the placebo laser session. However, the photobiomodulation was not able of increasing muscle performance measured by the isokinetic dynamometer. Thus, it can be conclude that the photobiomodulation was effective in reducing fatigue levels. However, no effects of photobiomodulation on muscle performance was observed.

  1. Isokinetic testing of biceps strength and endurance in dominant versus nondominant upper extremities.

    PubMed

    Wittstein, Jocelyn; Queen, Robin; Abbey, Alicia; Moorman, Claude T

    2010-09-01

    The strength and endurance of the contralateral biceps muscle can serve as a useful comparison for the operative limb following distal biceps repairs, mid-substance repairs, or tenotomy or tenodesis of the long head. There are limited data available on the effect of handedness on biceps strength and endurance. The dominant upper extremity has greater elbow flexion and supination peak torque and endurance. Subjects with no history of prior upper extremity injury or limitations completed isokinetic testing of biceps flexion and supination peak torque and endurance on a Biodex machine. A paired student t test was used to compare peak torque and endurance for both supination and flexion for the dominant and nondominant upper extremities. The results were analyzed for the entire group, and for male and female subjects separately as well. A power analysis revealed that 5 subjects were needed to achieve 80% power. Twenty subjects (10 male, 10 female) were tested. No significant difference was detected for peak torque or endurance for supination or flexion between the dominant and nondominant upper extremities. No difference was detected when the group was analyzed as a whole, nor when men and women were analyzed separately. The dominant and nondominant upper extremities demonstrate similar peak torque and endurance for supination and flexion. The normal contralateral upper extremity can be used as a matched control in the evaluation of post operative biceps isokinetic strength and endurance without adjusting results for handedness. (c) 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  2. Isokinetic clinical assessment of rotator cuff strength in subacromial shoulder impingement.

    PubMed

    Land, Helen; Gordon, Susan; Watt, Kerrianne

    2017-02-01

    Current conservative management of subacromial shoulder impingement (SSI) includes generic strengthening exercises, especially for internal (IR) and external (ER) shoulder rotators. However, there is no evidence that the strength or the ratio of strength between these muscle groups is different between those with SSI (cases) and an asymptomatic population (controls). To identify if isokinetic rotator cuff strength or the ratio of strength is significantly different between cases and controls. Case Control Study. Fifty one cases with SSI and 51 asymptomatic controls matched for age, gender, hand dominance and physical activity level completed isokinetic peak torque glenohumeral IR and ER testing. Within the SSI group, 31 dominant limbs were symptomatic and 20 non-dominant limbs were symptomatic. IR and ER were measured separately using continuous reciprocal concentric (con) and eccentric (ecc) contraction cycles at a speed of 60 degrees per second and again at 120 degrees per second. Values of peak torque (PT), relative peak torque (RPT) and ratios were compared using independent t-tests between the SSI and asymptomatic groups. Significant strength differences between the two groups were present only when the symptomatic SSI shoulder was the dominant shoulder (con ER PT at 60°/second, ecc ER PT at 120°/second, ecc ER RPT at 120°/second and ecc IR PT at 60°/second and 120°/second). Changes in rotator cuff strength in SSI may be related to limb dominance, which may have implications for strengthening regimes. Level 3a. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Influence of a brisk walking program on isokinetic muscular capacities of knee in sedentary older women.

    PubMed

    Bernard, P L; Tallon, G; Ninot, G; Jaussent, A; Ramdani, S; Coste, O; Picot, M C; Blain, H

    2016-12-01

    This study analyzed the evolution in peak torque (PT) and mean power (MP) isokinetic parameters in the quadriceps and hamstring muscles of elderly sedentary women who were randomly selected to participate in a brisk walking program for 6 months. The 121 sedentary women of this study presented a mean score of 5.3 (±1.7) on the Physical Activity Questionnaire for the Elderly and covered 86 % of the theoretical distance on the 6-min walk test. The isokinetic evaluation was performed on both sides at 60°/s and 180°/s. PT and MP were selected for analysis. Women in the trained group (n = 61) participated in a program of 78 sessions over 6 months with three sets of 60 min of exercise per week. For this group, heart rate, time and distance were, respectively, 125.2 bt/min (±10), 37.9 min (±4.2) and 3756.3 m (±445.4). The analysis of the group × time interaction demonstrated an increase in the PT of the dominant-side hamstrings (p < 0.001). In the trained group, we observed a significant increase in PT at 60°/s for the hamstrings on both sides (0.01 < p < 0.02) and a significant increase in MP for the hamstrings at 60°/s on the nondominant side (p < 0.05). The study indicates a minor, though significant, influence of a brisk walking program on the peak torque and mean power of the quadriceps and hamstring muscles in sedentary women over 60 years.

  4. Analysis of isokinetic muscle function and postural control in individuals with intermittent claudication

    PubMed Central

    Lanzarin, Morgan; Parizoto, Patricia; Santos, Gilmar M.

    2016-01-01

    BACKGROUND: Intermittent claudication (IC) is a debilitating condition that mostly affects elderly people. IC is manifested by a decrease in ambulatory function. Individuals with IC present with motor and sensory nerve dysfunction in the lower extremities, which may lead to deficits in balance. OBJECTIVE: This study aimed to measure postural control and isokinetic muscle function in individuals with intermittent claudication. METHOD: The study included 32 participants of both genders, 16 IC participants (mean age: 64 years, SD=6) and 16 healthy controls (mean age: 67 years, SD=5), which were allocated into two groups: intermittent claudication group (ICG) and control group (CG). Postural control was assessed using the displacement and velocity of the center of pressure (COP) during the sensory organization test (SOT) and the motor control test (MCT). Muscle function of the flexor and extensor muscles of the knee and ankle was measured by an isokinetic dynamometer. Independent t tests were used to calculate the between-group differences. RESULTS: The ICG presented greater displacement (p =0.027) and speed (p =0.033) of the COP in the anteroposterior direction (COPap) during the MCT, as well as longer latency (p =0.004). There were no between-group differences during the SOT. The ICG showed decreased muscle strength and power in the plantar flexors compared to the CG. CONCLUSION: Subjects with IC have lower values of strength and muscle power of plantiflexores, as well as changes in postural control in dynamic conditions. These individuals may be more vulnerable to falls than healthy subjects. PMID:26786077

  5. Asymmetry of the Isokinetic Trunk Rotation Strength of Korean Male Professional Golf Players

    PubMed Central

    Bae, Jung Hyun; Kim, Don-Kyu; Kang, Si Hyun; Hwang, Junah

    2012-01-01

    Objective To determine whether there is side to side difference of the trunk rotation muscle in Korean male professional golf players. Healthy controls who did not play golf were also evaluated and compared with professional golf players. Method Fifty-one professional golf players and 50 healthy controls participated in this study. Bilateral isokinetic trunk rotation strength that represented the aiming side and non-aiming side trunk rotator function in a golf swing and other parameters were evaluated using the Biodex System III Isokinetic Dynamometer at angular velocities of 30, 60, and 120 degree per second. Results The professional golf players' peak torque and total work on their aiming sides were significantly higher than on their non-aiming side at all angular velocities. Additionally, the golf players' peak torque on their aiming side was significantly higher than those of the healthy controls only at the 60 degree per second angular velocity, but there was a slight and consistent trend in the others. Finally, the difference between the aiming side and the non-aiming side of the professional golf players and the healthy controls was also significant. Conclusion The aiming side rotation strength of the male professional golf players was higher than that of non-aiming side. The controls showed no side-to-side differences. This finding is attributed to the repetitive training and practice of professional golf players. A further study is needed to investigate if the strengthening of the trunk rotation muscle, especially on the aiming side, could improve golf performance. PMID:23342315

  6. The Effect of Sex and Age on Isokinetic Hip-Abduction Torques

    PubMed Central

    Brent, Jensen L.; Myer, Gregory D.; Ford, Kevin R.; Paterno, Mark V.; Hewett, Timothy E.

    2014-01-01

    Context As high school female athletes demonstrate a rate of noncontact anterior cruciate ligament (ACL) injury 3–6 times higher than their male counterparts, research suggests that sagittal-plane hip strength plays a role in factors associated with ACL injuries. Objective To determine if gender or age affect hip-abductor strength in a functional standing position in young female and male athletes. Design Prospective cohort design. Setting Biomechanical laboratory. Participants Over a 3-y time period, 852 isokinetic hip-abduction evaluations were conducted on 351 (272 female, 79 male) adolescent soccer and basketball players. Intervention Before testing, athletes were secured in a standing position, facing the dynamometer head, with a strap secured from the uninvolved side and extending around the waist just above the iliac crest. The dynamometer head was positioned in line with the body in the coronal plane by aligning the axis of rotation of the dynamometer with the center of hip rotation. Subjects performed 5 maximum-effort repetitions at a speed of 120°/s. The peak torque was recorded and normalized to body mass. All test trials were conducted by a single tester to limit potential interrater test error. Main Outcome Measure Standing isokinetic hip-abduction torque. Results Hip-abduction torque increased in both males and females with age (P < .001) on both the dominant and nondominant sides. A significant interaction of gender and age was observed (P < .001), which indicated that males experienced greater increases in peak torque relative to body weight than did females as they matured. Conclusions Males exhibit a significant increase in normative hip-abduction strength, while females do not. Future study may determine if the absence of similar increased relative hip-abduction strength in adolescent females, as they age, may be related to their increased risk of ACL injury compared with males. PMID:22715125

  7. Chamaebatiaria millefolium (Torr.) Maxim.: fernbush

    Treesearch

    Nancy L. Shaw; Emerenciana G. Hurd

    2008-01-01

    Fernbush - Chamaebatiaria millefolium (Torr.) Maxim. - the only species in its genus, is endemic to the Great Basin, Colorado Plateau, and adjacent areas of the western United States. It is an upright, generally multistemmed, sweetly aromatic shrub 0.3 to 2 m tall. Bark of young branches is brown and becomes smooth and gray with age. Leaves are leathery, alternate,...

  8. Maximizing Pharmacy's Contribution to Society.

    ERIC Educational Resources Information Center

    Marston, Robert Q.

    1978-01-01

    It is argued that the role of colleges in the effort to maximize pharmacy's contribution to society requires an emphasis on research in the pharmaceutical sciences, in the clinical use of drugs, and in the socioeconomic aspects of drug therapy. This will produce more qualified pharmacists and greater credibility for the profession. (JMD)

  9. Maximizing Human Learning and Performance.

    ERIC Educational Resources Information Center

    Fletcher, Jerry L.

    1978-01-01

    Stating that national educational policy increasingly involves the minimum competencies mentality, the author discusses his proposal to investigate the outer limits of human educability, addressing five steps toward creating educational programs to maximize human educability: master patterns, personal patterns, stages of development, educational…

  10. A new augmentation based algorithm for extracting maximal chordal subgraphs

    DOE PAGES

    Bhowmick, Sanjukta; Chen, Tzu-Yi; Halappanavar, Mahantesh

    2014-10-18

    If every cycle of a graph is chordal length greater than three then it contains an edge between non-adjacent vertices. Chordal graphs are of interest both theoretically, since they admit polynomial time solutions to a range of NP-hard graph problems, and practically, since they arise in many applications including sparse linear algebra, computer vision, and computational biology. A maximal chordal subgraph is a chordal subgraph that is not a proper subgraph of any other chordal subgraph. Existing algorithms for computing maximal chordal subgraphs depend on dynamically ordering the vertices, which is an inherently sequential process and therefore limits the algorithms’more » parallelizability. In our paper we explore techniques to develop a scalable parallel algorithm for extracting a maximal chordal subgraph. We demonstrate that an earlier attempt at developing a parallel algorithm may induce a non-optimal vertex ordering and is therefore not guaranteed to terminate with a maximal chordal subgraph. We then give a new algorithm that first computes and then repeatedly augments a spanning chordal subgraph. After proving that the algorithm terminates with a maximal chordal subgraph, we then demonstrate that this algorithm is more amenable to parallelization and that the parallel version also terminates with a maximal chordal subgraph. That said, the complexity of the new algorithm is higher than that of the previous parallel algorithm, although the earlier algorithm computes a chordal subgraph which is not guaranteed to be maximal. Finally, we experimented with our augmentation-based algorithm on both synthetic and real-world graphs. We provide scalability results and also explore the effect of different choices for the initial spanning chordal subgraph on both the running time and on the number of edges in the maximal chordal subgraph.« less

  11. A New Augmentation Based Algorithm for Extracting Maximal Chordal Subgraphs.

    PubMed

    Bhowmick, Sanjukta; Chen, Tzu-Yi; Halappanavar, Mahantesh

    2015-02-01

    A graph is chordal if every cycle of length greater than three contains an edge between non-adjacent vertices. Chordal graphs are of interest both theoretically, since they admit polynomial time solutions to a range of NP-hard graph problems, and practically, since they arise in many applications including sparse linear algebra, computer vision, and computational biology. A maximal chordal subgraph is a chordal subgraph that is not a proper subgraph of any other chordal subgraph. Existing algorithms for computing maximal chordal subgraphs depend on dynamically ordering the vertices, which is an inherently sequential process and therefore limits the algorithms' parallelizability. In this paper we explore techniques to develop a scalable parallel algorithm for extracting a maximal chordal subgraph. We demonstrate that an earlier attempt at developing a parallel algorithm may induce a non-optimal vertex ordering and is therefore not guaranteed to terminate with a maximal chordal subgraph. We then give a new algorithm that first computes and then repeatedly augments a spanning chordal subgraph. After proving that the algorithm terminates with a maximal chordal subgraph, we then demonstrate that this algorithm is more amenable to parallelization and that the parallel version also terminates with a maximal chordal subgraph. That said, the complexity of the new algorithm is higher than that of the previous parallel algorithm, although the earlier algorithm computes a chordal subgraph which is not guaranteed to be maximal. We experimented with our augmentation-based algorithm on both synthetic and real-world graphs. We provide scalability results and also explore the effect of different choices for the initial spanning chordal subgraph on both the running time and on the number of edges in the maximal chordal subgraph.

  12. A new augmentation based algorithm for extracting maximal chordal subgraphs

    SciTech Connect

    Bhowmick, Sanjukta; Chen, Tzu-Yi; Halappanavar, Mahantesh

    2014-10-18

    If every cycle of a graph is chordal length greater than three then it contains an edge between non-adjacent vertices. Chordal graphs are of interest both theoretically, since they admit polynomial time solutions to a range of NP-hard graph problems, and practically, since they arise in many applications including sparse linear algebra, computer vision, and computational biology. A maximal chordal subgraph is a chordal subgraph that is not a proper subgraph of any other chordal subgraph. Existing algorithms for computing maximal chordal subgraphs depend on dynamically ordering the vertices, which is an inherently sequential process and therefore limits the algorithms’ parallelizability. In our paper we explore techniques to develop a scalable parallel algorithm for extracting a maximal chordal subgraph. We demonstrate that an earlier attempt at developing a parallel algorithm may induce a non-optimal vertex ordering and is therefore not guaranteed to terminate with a maximal chordal subgraph. We then give a new algorithm that first computes and then repeatedly augments a spanning chordal subgraph. After proving that the algorithm terminates with a maximal chordal subgraph, we then demonstrate that this algorithm is more amenable to parallelization and that the parallel version also terminates with a maximal chordal subgraph. That said, the complexity of the new algorithm is higher than that of the previous parallel algorithm, although the earlier algorithm computes a chordal subgraph which is not guaranteed to be maximal. Finally, we experimented with our augmentation-based algorithm on both synthetic and real-world graphs. We provide scalability results and also explore the effect of different choices for the initial spanning chordal subgraph on both the running time and on the number of edges in the maximal chordal subgraph.

  13. Validation of a Compact Isokinetic Total Water Content Probe for Wind Tunnel Characterization at NASA Glenn Icing Research Tunnel and at NRC Ice Crystal Tunnel

    NASA Technical Reports Server (NTRS)

    Davison, Craig R.; Landreville, Charles; Ratvasky, Thomas P.

    2017-01-01

    A new compact isokinetic probe to measure total water content in a wind tunnel environment has been developed. The probe has been previously tested under altitude conditions. This paper presents a comprehensive validation of the probe under a range of liquid water conditions at sea level in the NASA Glenn Icing Research Tunnel and with ice crystals at sea level at the NRC wind tunnel. The compact isokinetic probe is compared to tunnel calibrations and other probes.

  14. Sex-Specific Impact of Ischemic Preconditioning on Tissue Oxygenation and Maximal Concentric Force

    PubMed Central

    Paradis-Deschênes, Pénélope; Joanisse, Denis R.; Billaut, François

    2017-01-01

    not meaningfully different between conditions and sexes. IPC increased muscle blood volume (↑[THb]) at rest and during recovery between sets, to the same extent in both sexes. Despite a similar IPC-induced initial increase in O2 delivery in both sexes, males displayed greater peripheral O2 extraction and greater strength enhancement. This ergogenic effect appears to be mediated in part via an up regulated oxidative function in males. We conclude that strength-trained males might benefit more from IPC than their female counterparts during repeated, maximal efforts. PMID:28105020

  15. Sex-Specific Impact of Ischemic Preconditioning on Tissue Oxygenation and Maximal Concentric Force.

    PubMed

    Paradis-Deschênes, Pénélope; Joanisse, Denis R; Billaut, François

    2016-01-01

    different between conditions and sexes. IPC increased muscle blood volume (↑[THb]) at rest and during recovery between sets, to the same extent in both sexes. Despite a similar IPC-induced initial increase in O2 delivery in both sexes, males displayed greater peripheral O2 extraction and greater strength enhancement. This ergogenic effect appears to be mediated in part via an up regulated oxidative function in males. We conclude that strength-trained males might benefit more from IPC than their female counterparts during repeated, maximal efforts.

  16. Effects of submaximal and maximal long-lasting contractions on the compliance of vastus lateralis tendon and aponeurosis in vivo.

    PubMed

    Ullrich, Anne Charlotte; Mademli, Lida; Arampatzis, Adamantios

    2009-06-01

    The present study investigated the effects of submaximal sustained and maximal repetitive contractions on the compliance of human vastus lateralis (VL) tendon and aponeurosis in vivo using two different fatiguing protocols. Twelve male subjects performed three maximum voluntary isometric contractions (MVC) of the knee extensors before and after two fatiguing protocols on a dynamometer. The first fatiguing protocol consisted of a long-lasting sustained isometric knee extension contraction at 25% MVC until failure (inability to hold the defined load). The second fatiguing protocol included long-lasting isokinetic (90 degrees/s) knee extension contractions, where maximum moment was exerted and failure was proclaimed when this value fell below 70% of unfatigued maximum isokinetic moment. Ultrasonography was used to determine the elongation and strain of the VL tendon and aponeurosis. Muscle fatigue was indicated by a significant decrease in maximum resultant knee extension moment (p<0.05) observed during the MVCs after both long-lasting contractions. No significant (p>0.05) differences in elongation and strain of the VL tendon and aponeurosis were found, when compared every 300 N (tendon force) before and after the fatiguing protocols. The present data indicate, that the VL tendon and aponeurosis in vivo do not suffer from changes in the compliance neither after long-lasting static mechanical loading (strain approximately 3.2%) nor after long-lasting cyclic mechanical loading (strain 6.2-5.5%).

  17. No Differences Between Alter G-Trainer And Active And Passive Recovery Strategies On Isokinetic Strength, Systemic Oxidative Stress And Perceived Muscle Soreness After Exercise-Induced Muscle Damage.

    PubMed

    Cooke, Matthew B; Nix, Carrie; Greenwood, Lori; Greenwood, Mike

    2016-11-28

    The incidence of muscle injuries is prevalent in elite sport athletes as well as weekend warriors and strategies that safely and effectively hasten recovery are highly desirable. The purpose of this study was to examine the differences between three recovery methods after eliciting muscle damage in recreationally active men relative to maximal isokinetic contractions, perceived muscle soreness and psychological mood states. Twenty-five recreationally active men (22.15±3.53yrs, 75.75±11.91kg, 180.52±7.3cm) were randomly matched by VO2 peak (53.86±6.65ml·kg·min) and assigned to one of three recovery methods: Anti-gravity Treadmill (G-Trainer) (N = 8), Conventional Treadmill (N = 8) or Static Stretching (N = 9). Recovery methods were performed 30 minutes, 24, 48 and 72 hours following a 45 minute downhill run. Following eccentrically-biased running, no significant differences were noted in isokinetic knee flexion and extension peak torque, systemic markers of muscle damage, oxidative stress and lipid peroxidation such as serum creatine kinase (CK), superoxide dismutase (SOD), and malondialdehyde (MDA), respectively, and subjective ratings of perceived muscle soreness between recovery methods. The G-Trainer group did however display a higher mood state as indicated by the Profile of Mood State global scores at 24 hours post-exercise when compared to the conventional treadmill recovery group (p=0.035). The improved mood state following the use of the anti-gravity treadmill may provide clinical relevance to other populations.

  18. Isokinetic muscle strength and readiness to return to sport following anterior cruciate ligament reconstruction: is there an association? A systematic review and a protocol recommendation.

    PubMed

    Undheim, Marit Baste; Cosgrave, Ciaran; King, Enda; Strike, Siobhán; Marshall, Brendan; Falvey, Éanna; Franklyn-Miller, Andrew

    2015-10-01

    Following anterior cruciate ligament reconstruction (ACLR), strength is a key variable in regaining full function of the knee. Isokinetic strength is commonly used as part of the return to sport (RTS) criteria. We systematically reviewed the isokinetic strength evaluation protocols that are currently being used following ACLR. A secondary aim was to suggest an isokinetic protocol that could meet RTS criteria. Articles were searched using ScienceDirect, PubMed and Sage Journals Online, combined with cross-checked reference lists of the publications. Protocol data and outcome measurements and RTS criteria were extracted from each article included in the review. 39 studies met the inclusion criteria and reported their isokinetic strength evaluation protocol following ACLR. The variables that were most commonly used were concentric/concentric mode of contraction (31 studies), angular velocity of 60°/s (29 studies), 3-5 repetitions (24 studies), range of motion of 0-90° (6 studies), and using gravity correction (9 studies). 8 studies reported strength limb symmetry index scores as part of their RTS criteria. There was no standardised isokinetic protocol following ACLR; isokinetic strength measures have not been validated as useful predictors of successful RTS. We propose a standard protocol to allow consistency of testing and accurate comparison of future research. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  19. Comparison of basic physical fitness, aerobic capacity, and isokinetic strength between national and international level high school freestyle swimmers

    PubMed Central

    Bae, Young-Hyeon; Yu, Jae-Ho; Lee, Suk Min

    2016-01-01

    [Purpose] This study aimed to compare basic physical fitness, aerobic capacity, and isokinetic strength between international and national level freestyle high school student swimmers. [Subjects and Methods] A total of 28 participants (14 international level swimmers and 14 national level freestyle high school student swimmers) with no known pathology were included. We used a cross-sectional study to examine three variables: basic physical fitness, aerobic capacity, and isokinetic strength. [Results] The mean values of these variables in the international level swimmers were higher than those in the national level swimmers. Swimmers are generally physically fit with a good competition record. [Conclusion] An appropriate training program, which considers specific individual characteristics is likely to have a positive impact on the improvement of total physical fitness, and subsequently, on the performance of the freestyle high school swimmer. PMID:27134379

  20. Abnormal isokinetic time-to-peak torque of the medial rotators of the shoulder in subjects with impingement syndrome.

    PubMed

    Mattiello-Rosa, Stela M; Camargo, Paula R; Santos, Alexandre A S; Pádua, Michelle; Reiff, Rodrigo B M; Salvini, Tania F

    2008-01-01

    The time-to-peak torque (TPT) and the peak torque ratio of the lateral to medial rotators (LR/MR) during isokinetic lateral and medial rotation of the shoulder were evaluated in patients with shoulder impingement and in healthy subjects. Fifteen patients with shoulder impingement on the dominant side and 9 healthy subjects were evaluated. TPT and LR/MR were measured bilaterally during isokinetic concentric lateral and medial rotation at 60 degrees/s and 180 degrees/s. The impingement group showed a bilateral decrease in the TPT during medial rotation for both 60 degrees/s and 180 degrees/s. No differences were found in the LR/MR between the groups. It is proposed that decreased (TPT) of the medial rotators can be used as a tool for early detection of shoulder impingement. Notably, the decreased time-to-peak torque of the medial rotators may occur before the alteration in the peak torque ratio.

  1. Effect of Exercise Speed and Isokinetic Feedback on the Middle and Lower Serratus Anterior Muscles during Push-up Exercises.

    PubMed

    Yoo, Won-Gyu

    2014-05-01

    [Purpose] This study assessed the use of different exercise speeds and isokinetic feedback on the middle and lower serratus anterior muscles during push-up exercises. [Subjects] Ten male workers voluntarily consented to participate in the study. [Methods] The subjects performed push-up exercises under three conditions. Surface electrodes were placed on the dominant right side of the middle and lower serratus anterior muscles. [Results] The middle and lower SA muscle activities under condition 2 were significantly decreased when compared with those under conditions 1 and 3. The middle SA activity under condition 3 was significantly increased when compared with that under condition 1. [Conclusion] This study suggests that proper selection of push-up exercise speed may be necessary for selective strengthening of the SA and that isokinetic feedback information obtained using an accelerator can help in selective strengthening of the middle SA.

  2. Comparison of basic physical fitness, aerobic capacity, and isokinetic strength between national and international level high school freestyle swimmers.

    PubMed

    Bae, Young-Hyeon; Yu, Jae-Ho; Lee, Suk Min

    2016-03-01

    [Purpose] This study aimed to compare basic physical fitness, aerobic capacity, and isokinetic strength between international and national level freestyle high school student swimmers. [Subjects and Methods] A total of 28 participants (14 international level swimmers and 14 national level freestyle high school student swimmers) with no known pathology were included. We used a cross-sectional study to examine three variables: basic physical fitness, aerobic capacity, and isokinetic strength. [Results] The mean values of these variables in the international level swimmers were higher than those in the national level swimmers. Swimmers are generally physically fit with a good competition record. [Conclusion] An appropriate training program, which considers specific individual characteristics is likely to have a positive impact on the improvement of total physical fitness, and subsequently, on the performance of the freestyle high school swimmer.

  3. Effects of Static and Dynamic Stretching on the Isokinetic Peak Torques and Electromyographic Activities of the Antagonist Muscles.

    PubMed

    Serefoglu, Abdullah; Sekir, Ufuk; Gür, Hakan; Akova, Bedrettin

    2017-03-01

    The aim of this study was to investigate if static and dynamic stretching exercises of the knee muscles (quadriceps and hamstring muscles) have any effects on concentric and eccentric isokinetic peak torques and electromyographic amplitudes (EMG) of the antagonist muscles. Twenty healthy male athletes (age between 18-30 years) voluntarily participated in this study. All of the subjects visited the laboratory to complete the following intervention in a randomized order on 5 separate days; (a) non-stretching (control), (b) static stretching of the quadriceps muscles, (c) static stretching of the hamstring muscles, (d) dynamic stretching of the quadriceps muscles, and (e) dynamic stretching of the hamstring muscles. Static stretching exercises either for the quadriceps or the hamstring muscles were carried out at the standing and sitting positions. Subjects performed four successive repetitions of each stretching exercises for 30 seconds in both stretching positions. Similar to static stretching exercises two different stretching modes were designed for dynamic stretching exercises. Concentric and eccentric isokinetic peak torque for the non-stretched antagonist quadriceps or hamstring muscles at angular velocities of 60°/sec and 240°/sec and their concurrent electromyographic (EMG) activities were measured before and immediately after the intervention. Isokinetic peak torques of the non-stretched agonist hamstring and quadriceps muscles did not represent any significant (p > 0.05) differences following static and dynamic stretching of the antagonist quadriceps and hamstring muscles, respectively. Similarly, the EMG activities of the agonist muscles exhibited no significant alterations (p > 0.05) following both stretching exercises of the antagonist muscles. According to the results of the present study it is possible to state that antagonist stretching exercises either in the static or dynamic modes do not affect the isokinetic peak torques and the EMG activities

  4. Knee-Joint Proprioception During 30-Day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily log proprioceptive training, would influence log proprioceptive tracking responses during Bed Rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a NO-Exercise (NOE) training control group (n = 5), and IsoTanic Exercise (ITE, n = 7) and IsoKinetic Exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min period / d, 5 d /week. Only the IKE group performed proprioceptive training using a now isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pro-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p less than 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9 +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.50, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both lsotonic exercise training (without additional propriaceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  5. Knee-joint proprioception during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily leg proprioceptive training, would influence leg proprioceptive tracking responses during bed rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a no-exercise (NOE) training control group (n = 5), and isotonic exercise (ITE, n = 7) and isokinetic exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min periods.d-1, 5 d.week-1. Only the IKE group performed proprioceptive training using a new isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pre-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p < 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9* +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.5%, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both isotonic exercise training (without additional proprioceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  6. Knee-Joint Proprioception During 30-Day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily log proprioceptive training, would influence log proprioceptive tracking responses during Bed Rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a NO-Exercise (NOE) training control group (n = 5), and IsoTanic Exercise (ITE, n = 7) and IsoKinetic Exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min period / d, 5 d /week. Only the IKE group performed proprioceptive training using a now isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pro-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p less than 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9 +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.50, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both lsotonic exercise training (without additional propriaceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  7. Knee-joint proprioception during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily leg proprioceptive training, would influence leg proprioceptive tracking responses during bed rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a no-exercise (NOE) training control group (n = 5), and isotonic exercise (ITE, n = 7) and isokinetic exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min periods.d-1, 5 d.week-1. Only the IKE group performed proprioceptive training using a new isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pre-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p < 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9* +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.5%, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both isotonic exercise training (without additional proprioceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  8. Isokinetic eccentric exercise can induce skeletal muscle injury within the physiologic excursion of muscle-tendon unit: a rabbit model

    PubMed Central

    Tsuang, Yang-Hwei; Lam, Shui-Ling; Wu, Lien-Chen; Chiang, Chang-Jung; Chen, Li-Ting; Chen, Pei-Yu; Sun, Jui-Sheng; Wang, Chien-Che

    2007-01-01

    Background and Purpose Intensive eccentric exercise can cause muscle damage. We simulated an animal model of isokinetic eccentric exercise by repetitively stretching stimulated triceps surae muscle-tendon units to determine if such exercise affects the mechanical properties of the unit within its physiologic excursion. Methods Biomechanical parameters of the muscle-tendon unit were monitored during isokinetic eccentric loading in 12 rabbits. In each animal, one limb (control group) was stretched until failure. The other limb (study group) was first subjected to isokinetic and eccentric cyclic loading at the rate of 10.0 cm/min to 112% (group I) or 120% (group II) of its initial length for 1 hour and then stretched to failure. Load-deformation curves and biomechanical parameters were compared between the study and control groups. Results When the muscle-tendon unit received eccentric cyclic loading to 112%, changes in all biomechanical parameters – except for the slope of the load-deformation curve – were not significant. In contrast, most parameters, including the slope of the load-deformation curve, peak load, deformation at peak load, total energy absorption, and energy absorption before peak load, significantly decreased after isokinetic eccentric cyclic loading to 120%. Conclusion We found a threshold for eccentrically induced injury of the rabbit triceps surae muscle at between 12% and 20% strain, which is within the physiologic excursion of the muscle-tendon units. Our study provided evidence that eccentric exercise may induce changes in the biomechanical properties of skeletal muscles, even within the physiologic range of the excursion of the muscle-tendon unit. PMID:17711591

  9. Eccentric and concentric isokinetic moment characteristics in the quadriceps and hamstrings of the chronic isolated posterior cruciate ligament injured knee

    PubMed Central

    MacLean, C. L.; Taunton, J. E.; Clement, D. B.; Regan, W.

    1999-01-01

    OBJECTIVE: Functional strength deficits associated with chronic isolated posterior cruciate ligament (PCL) insufficiency have received limited attention in the literature. The purpose of this study was to determine the eccentric and concentric isokinetic moment characteristics of the quadriceps and hamstrings in a sample of patients with isolated PCL injury. METHODS: Eccentric and concentric mean average and average peak moments were measured for 17 patients with a history of conservatively treated isolated PCL injury using an isokinetic dynamometer. Quadriceps and hamstring isokinetic moments were recorded from 10 degree to 90 degree of knee flexion. Strength ratios were calculated and compared with those reported in the literature for healthy subjects. RESULTS: The hamstrings of the involved side (eccentric/concentric (E/C) ratio = 1.06) were significantly weaker (p<0.05) eccentrically than those of the contralateral side (E/C ratio = 1.29). All hamstrings/quadriceps (H/Q) ratios were less than the universally accepted value of 0.60 and the eccentric H/Q ratio for the injured extremity was significantly lower than the non-injured (p<0.05). In a bilateral comparison, the injured/non-injured (I/N) ratio was less than 1.00 for concentric quadriceps, eccentric quadriceps, and hamstring isokinetic moments. Calculation of the E/C ratio showed that, for the quadriceps, it was 1.08 on the injured side and 1.07 on the non-injured extremity. CONCLUSIONS: Eccentric strengthening should be an integral part of functionally rehabilitating the quadriceps and hamstrings of athletes who suffer from the complications associated with chronic isolated PCL insufficiency. 


 PMID:10597850

  10. Isokinetic shoulder strength correlates with level of sports participation and functional activity after reverse total shoulder arthroplasty.

    PubMed

    Wang, Allan; Doyle, Timothy; Cunningham, Gregory; Brutty, Michael; Campbell, Peter; Bharat, Chrianna; Ackland, Timothy

    2016-09-01

    Reverse total shoulder arthroplasty (RTSA) is increasingly being performed. Many patients may wish to return to high levels of sporting activity. This study aimed to evaluate the correlation of isokinetic shoulder strength with level of participation in sport and recreation after RTSA. We surveyed 51 patients at a mean of 29.5 months (range, 12-60 months) after surgery. Mean age was 74.1 years. Patient-reported sporting activity was classified as low, medium, or high demand. All patients completed the shortened Disabilities of the Arm, Shoulder, and Hand questionnaire and the Oxford Shoulder Score and underwent Biodex dynamometer testing of the RTSA evaluating isokinetic shoulder strength in flexion and extension, abduction and adduction, and internal and external rotation. Reported sporting activity was high demand in 35% and moderate demand in 43%. There was a large variation in shoulder isokinetic strength parameters especially for internal and external rotation. With the exception of abduction, a significant correlation was noted between strength and the level of sports participation that patients reported (P < .03). A significant correlation was also noted between strength and patient-reported outcome measures for internal rotation and arm flexion and abduction (P < .05). Most patients reported returning to moderate- or high-level sporting activity in the short term after RTSA. Isokinetic shoulder strength, especially in internal rotation and arm flexion, positively correlates with both patient-reported level of participation in sports and recreation and daily function. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  11. Oxidative stress and inflammatory responses following an acute bout of isokinetic exercise in obese women with knee osteoarthritis.

    PubMed

    Germanou, Evangelia I; Chatzinikolaou, Athanasios; Malliou, Paraskevi; Beneka, Anastasia; Jamurtas, Athanasios Z; Bikos, Christos; Tsoukas, Dimitrios; Theodorou, Apostolos; Katrabasas, Ioannis; Margonis, Konstantinos; Douroudos, Ioannis; Gioftsidou, Asimenia; Fatouros, Ioannis G

    2013-12-01

    Obesity is associated with osteoarthritis and it is accompanied by chronic inflammation and elevated oxidative stress. Strengthening-type exercise is used in knee osteoarthritis (KOA) rehabilitation. This study determined how acute isokinetic exercise influences inflammatory responses of obese middle-aged women with KOA. Ten obese women with KOA and 10 age/weight-matched controls performed an isokinetic exercise protocol. Assessment of performance (knee extensor/flexor torque), muscle soreness (DOMS), knee flexibility (KJRM), and pain, and blood collection were performed pre-exercise, post-exercise, and at 24h post-exercise. Blood was analyzed for creatine kinase activity (CK), lactate dehydrogenase activity (LDH), CRP, leukocytes, uric acid, IL-6, TBARS, lipid hydroperoxides (LPX), protein carbonyls (PC), oxidized (GSH) and reduced glutathione (GSSG), total antioxidant capacity (TAC), catalase activity, and glutathione peroxidase activity (GPX). Physical function remained unaltered by exercise (only torque at 90°/s decreased at 24h). Exercise increased DOMS throughout recovery but KJRM and pain remained unchanged. CK, LDH, and uric acid increased similarly in both groups. CRP remained unaffected by exercise while IL-6 increased only post-exercise. TBARS, PC, LPH, GSSG, and TAC increased only post-exercise in both groups. GSH and GSH/GSSG declined post-exercise and normalized thereafter. Catalase and GPX increased only in patients post-exercise. Isokinetic exercise induces only a mild inflammatory response of very short duration (<24h) without affecting physical function and pain in KOA patients suggesting that moderate strengthening-type exercise may be safe for this patient cohort. These results indicate that KOA patients may be able to receive another exercise stimulus after only 48h. Isokinetic exercise produces minimal inflammation and pain in knee osteoarthritis patients, could be performed every 48h during rehabilitation, and up-regulates patients

  12. Maximization, learning, and economic behavior

    PubMed Central

    Erev, Ido; Roth, Alvin E.

    2014-01-01

    The rationality assumption that underlies mainstream economic theory has proved to be a useful approximation, despite the fact that systematic violations to its predictions can be found. That is, the assumption of rational behavior is useful in understanding the ways in which many successful economic institutions function, although it is also true that actual human behavior falls systematically short of perfect rationality. We consider a possible explanation of this apparent inconsistency, suggesting that mechanisms that rest on the rationality assumption are likely to be successful when they create an environment in which the behavior they try to facilitate leads to the best payoff for all agents on average, and most of the time. Review of basic learning research suggests that, under these conditions, people quickly learn to maximize expected return. This review also shows that there are many situations in which experience does not increase maximization. In many cases, experience leads people to underweight rare events. In addition, the current paper suggests that it is convenient to distinguish between two behavioral approaches to improve economic analyses. The first, and more conventional approach among behavioral economists and psychologists interested in judgment and decision making, highlights violations of the rational model and proposes descriptive models that capture these violations. The second approach studies human learning to clarify the conditions under which people quickly learn to maximize expected return. The current review highlights one set of conditions of this type and shows how the understanding of these conditions can facilitate market design. PMID:25024182

  13. Maximization, learning, and economic behavior.

    PubMed

    Erev, Ido; Roth, Alvin E

    2014-07-22

    The rationality assumption that underlies mainstream economic theory has proved to be a useful approximation, despite the fact that systematic violations to its predictions can be found. That is, the assumption of rational behavior is useful in understanding the ways in which many successful economic institutions function, although it is also true that actual human behavior falls systematically short of perfect rationality. We consider a possible explanation of this apparent inconsistency, suggesting that mechanisms that rest on the rationality assumption are likely to be successful when they create an environment in which the behavior they try to facilitate leads to the best payoff for all agents on average, and most of the time. Review of basic learning research suggests that, under these conditions, people quickly learn to maximize expected return. This review also shows that there are many situations in which experience does not increase maximization. In many cases, experience leads people to underweight rare events. In addition, the current paper suggests that it is convenient to distinguish between two behavioral approaches to improve economic analyses. The first, and more conventional approach among behavioral economists and psychologists interested in judgment and decision making, highlights violations of the rational model and proposes descriptive models that capture these violations. The second approach studies human learning to clarify the conditions under which people quickly learn to maximize expected return. The current review highlights one set of conditions of this type and shows how the understanding of these conditions can facilitate market design.

  14. The effect of peculiar complex core balance training on isokinetic muscle functions of the knee and lumbus

    PubMed Central

    Lee, Myungsun; Han, Gunsoo

    2016-01-01

    [Purpose] This study aimed to investigate the effect of peculiar complex core balance training on the isokinetic muscle function of the knee joint and lumbus to provide fundamental data for establishing a training program that focuses on improving the performance and prevention of injury by developing the core and low extremity muscles. [Subjects and Methods] The participants in this study included a total of ten high school athletes involved in a throwing event for over five years. The subjects were randomly divided into two groups: The experimental group (N=5) and the control group (N=5). The experimental group underwent peculiar complex core balance training. [Results] According to the analysis of covariance, there was a significant effect of peculiar complex core balance training. Therefore, the isokinetic muscle function of the knee joint and lumbus in the experimental group participating in peculiar complex core balance training was significantly increased compared to the control group. [Conclusion] It is concluded that peculiar complex core balance training had a positive effect on the isokinetic muscle function of the knee and lumbus in throwing event athletes. PMID:27190470

  15. Relative appendicular skeletal muscle mass is associated with isokinetic muscle strength and balance in healthy collegiate men.

    PubMed

    Kim, Sung-Eun; Hong, Ju; Cha, Jun-Youl; Park, Jung-Min; Eun, Denny; Yoo, Jaehyun; Jee, Yong-Seok

    2016-11-01

    There are few studies on the relationship between skeletal muscle mass and balance in the young ages. We investigated the relationship between appendicular skeletal muscle mass, isokinetic muscle strength of lower extremity, and balance among healthy young men using relative skeletal muscle index. Thirty men were grouped according to relative appendicular skeletal muscle mass index: higher skeletal muscle group (n = 15) and lower skeletal muscle group (n = 15). Static and dynamic balance abilities were measured using the following: a test where participants stood on one leg with eyes closed, a modified Clinical Test of Sensory Interaction on Balance (mCTSIB) with eyes open and eyes closed, a stability test, and limits of stability test. The muscle strength of lower extremities was measured with an isokinetic analyser in hip, knee, and ankle joints. Participants with higher appendicular skeletal muscle mass were significantly more stable in maintaining dynamic balance than those with lower appendicular skeletal muscle mass. Moreover, appendicular skeletal muscle mass index was positively correlated with dynamic balance ability. Participants with higher appendicular skeletal muscle mass had stronger strength in the lower extremity, and there were significant differences in the isokinetic torque ratios between groups. From these results, it can be inferred that higher appendicular skeletal muscle mass relates to muscle strength and the alteration in the peak torque ratio of the lower extremity, contributing to the maintenance of balance.

  16. [Chronic chondromalacia of the patella: comparison of morphological (magnetic resonance) and functional findings (isokinetic parameters) after rehabilitation].

    PubMed

    Felicetti, G; Avanza, F; Fiori, M; Brignoli, E; Rovescala, R

    1996-01-01

    The knee is a common site for injuries of the cartilage, capsule and ligament, which calls for the use of noninvasive techniques to assess injury severity properly and to plan adequate rehabilitation. Our study was aimed at comparing MR with isokinetic findings. To this purpose, 40 patients were examined; they were all affected with chondromalacia patellae, grades I-III, previously diagnosed at arthroscopy. Namely, 8 patients had grade I and 32 grades II and III chondromalacia. After MR and isokinetic exams, all patients were submitted to a standardized rehabilitation program. Our results indicate a marked decrease in quadriceps strength, especially in the most severe cases; in less severe cases, recovery was complete at 6 months, while the deficit remained in grades II and III injuries. MR yield was not relevant in 4 of 8 cases, while isokinetic findings were negative in one case. Both methods were positive in the most severe cases. At 6 months, both functional and MR findings were normal in grade I injuries, while some alterations remained in the others.

  17. The effect of peculiar complex core balance training on isokinetic muscle functions of the knee and lumbus.

    PubMed

    Lee, Myungsun; Han, Gunsoo

    2016-04-01

    [Purpose] This study aimed to investigate the effect of peculiar complex core balance training on the isokinetic muscle function of the knee joint and lumbus to provide fundamental data for establishing a training program that focuses on improving the performance and prevention of injury by developing the core and low extremity muscles. [Subjects and Methods] The participants in this study included a total of ten high school athletes involved in a throwing event for over five years. The subjects were randomly divided into two groups: The experimental group (N=5) and the control group (N=5). The experimental group underwent peculiar complex core balance training. [Results] According to the analysis of covariance, there was a significant effect of peculiar complex core balance training. Therefore, the isokinetic muscle function of the knee joint and lumbus in the experimental group participating in peculiar complex core balance training was significantly increased compared to the control group. [Conclusion] It is concluded that peculiar complex core balance training had a positive effect on the isokinetic muscle function of the knee and lumbus in throwing event athletes.

  18. Strength field tests performance are correlated with isokinetic strength of shoulder rotator muscles in female handball players.

    PubMed

    Dos S Andrade, M; Fachina, R J; Cruz, W; Benedito-Silva, A A; Da Silva, A C; De Lira, C A

    2014-08-01

    The aim of this study was to analyze the relationship between the isokinetic shoulder strength of the athletes and their performance on strength field tests. Data on the balance and functional strength ratios of the internal and external rotator muscles of shoulders of handball players was also investigated. Twenty-seven female athletes (23±3.4 years, 71±10.6 kg and 173.3±7.1 cm) underwent an isokinetic assessment of the strength of the shoulder rotator muscles. Athletes also performed the following strength field tests: bench press test, lying bench barbell row test, handgrip test, and medicine ball throwing. The bench press test results and the lying bench barbell row test results were significantly correlated with the concentric internal and external rotator peak torques at 1.05 rad.s-1 and 5.23 rad.s-1, with total work at 1.05 rad.s-1 and with average power at 5.23 rad.s-1 (r=0.51 to 0.81). We suggested the use of field test to infer about internal and external rotator muscular strength, but not to infer about isokinetic muscular strength ratios. These findings could be useful to coaches and trainers.

  19. Rate analysis for a hybrid quantum repeater

    SciTech Connect

    Bernardes, Nadja K.; Loock, Peter van

    2011-01-15

    We present a detailed rate analysis for a hybrid quantum repeater assuming perfect memories and using optimal probabilistic entanglement generation and deterministic swapping routines. The hybrid quantum repeater protocol is based on atomic qubit-entanglement distribution through optical coherent-state communication. An exact, analytical formula for the rates of entanglement generation in quantum repeaters is derived, including a study on the impacts of entanglement purification and multiplexing strategies. More specifically, we consider scenarios with as little purification as possible and we show that for sufficiently low local losses, such purifications are still more powerful than multiplexing. In a possible experimental scenario, our hybrid system can create near-maximally entangled (F=0.98) pairs over a distance of 1280 km at rates of the order of 100 Hz.

  20. Associations of maximal strength and muscular endurance test scores with cardiorespiratory fitness and body composition.

    PubMed

    Vaara, Jani P; Kyröläinen, Heikki; Niemi, Jaakko; Ohrankämmen, Olli; Häkkinen, Arja; Kocay, Sheila; Häkkinen, Keijo

    2012-08-01

    The purpose of the present study was to assess the relationships between maximal strength and muscular endurance test scores additionally to previously widely studied measures of body composition and maximal aerobic capacity. 846 young men (25.5 ± 5.0 yrs) participated in the study. Maximal strength was measured using isometric bench press, leg extension and grip strength. Muscular endurance tests consisted of push-ups, sit-ups and repeated squats. An indirect graded cycle ergometer test was used to estimate maximal aerobic capacity (V(O2)max). Body composition was determined with bioelectrical impedance. Moreover, waist circumference (WC) and height were measured and body mass index (BMI) calculated. Maximal bench press was positively correlated with push-ups (r = 0.61, p < 0.001), grip strength (r = 0.34, p < 0.001) and sit-ups (r = 0.37, p < 0.001) while maximal leg extension force revealed only a weak positive correlation with repeated squats (r = 0.23, p < 0.001). However, moderate correlation between repeated squats and V(O2)max was found (r = 0.55, p < 0.001) In addition, BM and body fat correlated negatively with muscular endurance (r = -0.25 - -0.47, p < 0.001), while FFM and maximal isometric strength correlated positively (r = 0.36-0.44, p < 0.001). In conclusion, muscular endurance test scores were related to maximal aerobic capacity and body fat content, while fat free mass was associated with maximal strength test scores and thus is a major determinant for maximal strength. A contributive role of maximal strength to muscular endurance tests could be identified for the upper, but not the lower extrem