bluuebunny/crossref_metadata_2025 huggingface dataset:
Are the antagonist muscles fatigued during a fatigue task of agonist muscles?
Authors: Kotzamanidis Christos
Published: October 2018

The purpose of this study was to examine if a fatigue task of agonist muscles also causes fatigue to the antagonist muscles. Fourteen(n = 14) healthy males (age: 24.3 ± 2.5 y) participated in two isokinetic fatigue protocols (IFPs) at the angular velocity of 60°/s. The motion ranged from 0° to 90° of knee flexion. The first protocol consisted of 25 concentric maximal trials. The second protocol consisted of 60 concentric submaximal trials with a resistance equal to 60% of the maximum isokinetic torque exerted at 60°s $^{-1}$ . The muscles selected for EMG recording were Vastus Medialis (VM) and Vastus Lateralis (VL) as agonists and Biceps Femoris (BF) as antagonist. Both protocols were performed with isolated extensions. However, reciprocal maximal knee extension-flexion trials were performed periodically for the estimation of torque and EMG activity of BF muscle. The obtained results indicate that both protocols cause a significant decrease of torque and EMG activity of the agonist muscles. On the contrary, they did not affect the torque and EMG activity of the antagonist muscle. Thus, it can be assumed that antagonist muscles are not fatigued during a fatigue task and they are regulated mainly by central neuronal mechanisms.
A comparison of isokinetic muscle strength and power in visually impaired and sighted individuals
Authors: Horvat Michael , Ray Christopher , Croce Ron , Blasch Bruce
Published: October 2018

The purpose of this investigation was to compare the isokinetic strength characteristics of visually impaired with sighted individuals. Thirty age-matched participants who met the criteria for blind and partially sighted were matched according to age, height, and sex. Participants were evaluated on a Cybex Isokinetic dynamometer at speeds of 90 and 180 deg/sec. The main outcome measures were peak torque normalized by body weight; and power adjusted by body weight. Data was analyzed by using separate 2 × 2 × 2 × 2 (group × gender× muscle × velocity) repeated measures analyses of variance (ANOVAs). Separate ANOVAs were performed because of the relatively low number of subjects used in the investigation. Results demonstrated significant group, velocity and muscle main effects; sighted individuals had significantly greater values for peak torque and power than individuals with visual impairments. In conclusion, it appears that individuals with visual impairments are deficient in strength and power compared to sighted individuals. Interventions programs should begin early in an individual's development and stress developing muscular strength and power.
Factors affecting the shoulder proprioceptive sense among male volleyball players
Authors: Kablan Nilüfer , Ertan Hayri , Ünver Fatma , Kirazci Sadettin , Korkusuz Feza
Published: October 2018

Proprioceptive sense plays an important role in shoulder joint movements and stability especially in executing performance like playing voleyball. The aim of this study was to evaluate the effect of different positions, the rotator cuff muscle fatigue and experience on shoulder proprioceptive sense among male volleyball players. Twenty elite and 20 beginner volleyball players participated in this cross-sectional study. Shoulder proprioceptive sense was determined by measuring participant's perception of joint position with the joint at 90° abduction, external rotation and 90° abduction, neutral rotation. Participants were tested at 2°/s before and after exercising on an isokinetic-testing machine until fatigued with dominant extremities were assessed. The results revealed significant difference between proprioceptive senses of beginner volleyball players at 10–20° and 15–20° in external rotation before fatigue. The proprioceptive sense of elite volleyball players before and after fatigue was statistically different at 20°, whereas for the beginner players significance was indicated at 10 and 15°. However, no significant difference was found between elite and beginners in the proprioceptive scores at the 3 angles in both directions before and after the fatigue test. It was concluded that the effect of fatigue on proprioceptive sense is related to experience, but experience itself had no effect on proprioceptive sense.
A randomised controlled trial of different leg extension exercises to increase quadriceps muscle strength in female students
Authors: Biette Nicolas , Tourny-Chollet Claire , Beuret-Blanquart Françoise
Published: October 2018

The purpose of this study was to compare the effects of two different types of resistance training in sedentary women. Twenty students were assigned to three groups: concentric training (CT), combined concentric and isometric training (ICT) and control (CN). The training protocol consisted of 8 weeks × 3 days. The results demonstrated improvements in both groups. However, greater isometric strength gains were achieved among ICT subjects but no difference regarding the concentric mode. The results indicate that quadriceps muscle strength may be greatly improved by combined training as compared to concentric training alone.
The use of low velocity submaximal eccentric contractions of the hamstring for recovery of full extension after total knee replacement: A randomized controlled study
Authors: Codine Ph. , Dellemme Y. , Denis-Laroque F. , Herisson Ch.
Published: October 2018

Recovery of full knee extension after total knee replacement (TKR) is necessary in order to obtain a good quality in walking. One of the means for accomplishing a successful rehabilitation of this operation is by using eccentric exercises of the hamstrings for increasing tendon- muscular extensibility. The findings regarding knee extension of 30 TKR patients who exercised this muscle group 15 min/day, 5 days/week from day10 to day30 following surgery were compared with a reference group of 30 TKR patients who did not train similarly. The experimental group achieved a significantly better extension but no differences were noted vis-a-vis RoM in flexion and quadriceps and hamstrings strength. Training was well tolerated without inflammatory reaction or hamstrings muscle pain. Therefore this technique may be prescribed for faster recovery of knee extension following TKR.
Concentric isokinetic dynamometry of the shoulder: Which parameters discriminate between healthy subjects and patients with shoulder disorders?
Authors: van Meeteren Jetty , Roebroeck Marij E. , Selles Ruud W. , Stijnen Theo , Stam Henk J.
Published: October 2018

There is no consensus on the optimal isokinetic dynamometry parameters to clinically assess shoulder disorders. Therefore, this study aimed to establish which parameters are best able to discriminate between shoulder patients and healthy subjects, focusing on peak torques and peak torque ratios.

Isokinetic dynamometric measurements of both shoulders were made in 20 healthy subjects and these data were compared with baseline measurements in 9 patients with shoulder disorders. The different outcome measures were compared by testing for significant group differences between patients and healthy subjects and by scoring how the patient data compared to the normal range of values found in healthy subjects.

Significant differences between patients and healthy subjects were found for the peak torques, but not for the agonist-antagonist peak torque ratios. In addition, there were significant differences for the dominant/non dominant ratios of the peak torques but not for the dominant/non dominant ratios of the peak torque ratios. The percentage of patients with a standard deviation score outside the 90% normal distribution of healthy subjects was largest (>78%) for the involved/uninvolved (I/U) ratio of the peak torques.

It was concluded that bilateral comparison of peak torques is the most appropriate outcome parameter to distinguish patients from healthy subjects.
Trunk strength patterns in elite rowers
Authors: McGregor Alison , Hill Adam , Grewar Jane
Published: October 2018

This study compared the strength and fatigue characteristics of the trunk in international rowers and non-rowing controls. 39 international rowers(mean age 27.4 ± 4.9, 20 females, 19 males) and 35 control subjects who did not row (mean age 23.2 ± 3.2, 20 males, 15 females) were recruited and parameters of trunk flexion-extension strength including isometric fatigue were recorded tested on a Cybex Norm Isokinetic Testing System.

The rowers were significantly stronger (P < 0.001) in all measured parameters of back strength than the control group (isometric extension strength 249.3 N/m ± 52.1 (SD) in rowers compared with 178.6 N/m ± 85 (SD) in controls). Greater strength in the rowing group was most significant in the later stages of range. Both populations demonstrated marked fatigue of the trunk muscles, although this was more prominent in the rowers (p < 0.05 in flexion). In general, values of extensor strength were markedly greater than flexion strength, although this was less so in rowers. Consequently the trunk extensor-flexor ratios were lower in the rowing population.

In conclusion, elite rowers are significantly stronger than control subjects. It is of interest that these strength gains are not proportional throughout range and this may be related to the rowing action, and may be of importance with respect to future development of LBP.
Relationship between isokinetic strength and shooting accuracy at different shooting ranges in Taiwanese elite high school basketball players
Authors: Tang W.-T. , Shung H.-M.
Published: October 2018

The aim of the present study was to determine the relationship between agonist concentric isokinetic strengths applicable to jump shooting motions and associated performance at different shooting ranges. Twenty-two elite high school basketball players participated in the present study. The accuracy of jump shooting (from the 2-point range to the 3-point range at six distance intervals) was derived from 20 attempts at each distance as an indicator of basketball shooting performance. Subjects also performed four maximal isokinetic efforts of the dominant knee extensor, shoulder flexor, and elbow extensor at angular velocities of 60, 180 and 300°/s, and of the wrist flexor at 60, 180, and 240°/s. Pearson correlation analyses were conducted to determine the relationships between isokinetic strengths and shooting accuracy at varied distances. Two-point shooting performance at 3.225 m was significantly correlated with wrist flexor torque (r=0.67; P<0.05) at the test angular velocity of 60°/s. Three-point shooting performance at 6.75 m was significantly correlated with elbow extensor torques (r=0.74; P<0.05) at the test angular velocities of 180 and 300°/s. We conclude that there is a significant correlation between short distance shooting accuracy and wrist isokinetic strength, and between long distance shooting accuracy and the elbow extensor isokinetic strength. This result suggests that specific isokinetic strength should be stressed in training, which may constrain performance of jump shooting for skilled high school basketball players.
Passive elastic properties of the calf muscle-tendon unit of distance runners
Authors: Gajdosik Richard L. , Riggin Tammy J.
Published: October 2018

Studies have suggested that distance runners have decreased calf muscle-tendon unit (MTU) flexibility, which is related to improved running economy. This study examined the passive elastic properties of the calf MTU of distance runners to test the hypothesis that they have increased passive elastic properties measured in vivo. Ten distance runners (aged 18–21 years) and 10 untrained men (aged 23–28 years) were tested. A Kin-Com® dynamometer stretched the right calf MTU from plantarflexion (PF) to maximal dorsiflexion (DF) at 5°·s $^{-1}$ (0.087 rad·s $^{-1}$ ) with minimal surface electromyogram activity in the soleus, gastrocnemius, and tibialis anterior muscles. ANOVA analyses indicated that the maximal DF ROM did not differ between groups, but the maximal passive DF torque (Nm), total absorbed passive elastic energy (area under full stretch curve [°·Nm]) and passive elastic stiffness(Nm·° $^{-1}$ ) within the last 10° of the stretch were greater for the distance runners when controlled for body mass(P⩽0.007). The maximal passive DF torque and the passive elastic stiffness were greater when controlled for PF maximal voluntary isometric contraction torque (P⩽0.028). The increased passive resistive properties suggested structural adaptations in the calf MTU, possibly the result of eccentric loading and stretching, which would contribute to improved running economy.
Isokinetic profile and differences in tibial rotation strength between male and female athletes 11 to 17 years of age
Authors: Noyes Frank R. , Barber-Westin Sue D.
Published: October 2018

Our objective was to examine age and sex associated development of isokinetic tibial rotation strength in 94 athletes aged 11 to 17 y. A calibrated Biodex system 3 was used to measure internal rotation (IR) and external rotation (ER) peak torque and time to peak torque (TPT) at 120°/s and 180°/s, and knee extension and flexion peak torque at 180°/s. All data were normalized for body weight and ANOVA identified significant (p<0.05) effects of lower limb dominance, age and gender. Males aged 14 to 17 y had significantly greater mean IR, ER, flexion, and extension peak torques than males aged 11 to 13 y. No such age-related effect existed in females. There was no difference between genders aged 11 to 13∼y in isokinetic strength. Males aged 14 to 17 y had on average 17% greater IR strength, 28% faster time to reach IR peak torque, 17% greater extension strength, and 20% greater knee flexion strength than age-matched females. To conclude, no sex differences were found in peak torque or TPT in knee IR, ER, extension or flexion in athletes 11 to 13 y. Age related changes were found in these factors in males, but not in females.
The effect of static and dynamic stretching exercises on the maximal isokinetic strength of the knee extensors and flexors
Authors: Papadopoulos G. , Siatras Th. , Kellis S.
Published: October 2018

Warm-up and stretching exercises constitute an essential part of physical preparation before any athletic event. The aim of this study was to examine the acute effect of static and dynamic stretching exercises on maximal isokinetic torque of knee extensor and flexor muscles. Thirty-two(n=32) physical education students aged 19–22 years were asked to perform three different protocols consisting of A) warm-up, B) warm-up and static stretching and C) warm-up and dynamic stretching exercises, on three non-consecutive days. Each treatment was followed by measurements of knee extensor and flexor muscles maximal concentric torque on an isokinetic dynamometer at 60 and 180°/s. ANOVA for repeated-measures revealed significant differences in maximal torque following the different protocols. Tukey's post hoc tests showed a reduced torque for knee extensor p<0.01) and knee flexor muscles(p<0.01) at both velocities when static stretching exercises preceded the test. These findings indicate the negative influence of the static stretching exercises on maximal isokinetic torque production, while dynamic stretching approach does not seem to have any inhibitory effect.
Differences of muscle oxygenation during eccentric and concentric contraction
Authors: Okamoto Takanobu , Masuhara Mitsuhiko , Ikuta Komei
Published: October 2018

The aims of the present study were to clarify the differences in muscle oxygen dynamics between eccentric (ECC) and concentric (CON) contractions and to investigate the relationship between muscle oxygen dynamics and the pattern of skeletal muscle recruitment during ECC and CON contractions. Fifteen healthy male subjects (age 21.8 ± 2 yrs) performed isokinetic ECC and CON knee extension and flexion exercise for 1 min at an angular velocity of 180°/s. Changes in muscle oxygenation (MO) levels in the active muscle were measured using near-infrared spectroscopy (NIRS) whose probe was placed on the rectus femoris. Bipolar surface electrodes recorded the electromyogram (EMG) activity of this muscle. The MO levels during ECC contraction were significantly higher at 10 s and 15 s after the onset of exercise while MO levels during CON contraction were significantly higher 60 s following the onset of exercise. A significant correlation was indicated between MO levels and EMG activity during CON contraction (p<0.05). These results reveal that oxygen supply-consumption balance in ECC and CON contraction are different. Moreover, this suggests that muscle activity in CON contraction increases and the oxygen supply to active muscle may exceed the oxygen consumption in active muscle.
Strength, muscular endurance and EMG characteristics of thigh adductors
Authors: Kadi Fawzi , Buskqvist Lars , Sjöholm Oskar , Folkesson Mattias , Karlsson Stefan J. , Gerdle Björn
Published: October 2018

The assessment of thigh adductors' strength and endurance and electromyographical (EMG) characteristics has received little attention compared to other muscle groups. The aim of this study was to investigate strength, endurance performance and EMG characteristics of m. adductor longus and m. gracilis during concentric thigh adduction in soccer and bandy players. Muscular endurance was evaluated using the torque reduction during 70 repeated maximum concentric adductions at an angular velocity of 60°/s. The EMG mean frequency (MNF) and the signal amplitude ratio (SAR, index for muscles' ability to relax between contractions) were analysed. Peak torque decreased significantly throughout the test and no significant differences were found between the two groups. In both muscles, MNF decreased significantly throughout the test. There were no significant differences in MNF and in SAR variables between soccer and bandy players. In conclusion, the present findings reveal a number of significant aspects related to strength and electromyography of hip adductors.
The size of physiological spinal curvatures and functional parameters of trunk muscles in children with idiopathic scoliosis
Authors: Anwajler Joanna , Skrzek Anna , Mraz Małgorzata , Skolimowski Tadeusz , Woźniewski Marek
Published: October 2018

Objective: To examine the influence of the spinal contour changes on the functioning of trunk muscles in children with idiopathic scoliosis.

Background: In the early stage of scoliosis progression, changes in the sagittal plane often manifest themselves in curving in the lumbar lordosis and curving out of the thoracal scoliosis. An increase or decrease in the size of anteroposterior spinal curvatures may disturb functioning of the trunk muscles.

Method: Thirty five girls (mean age: 14.7 ± 2.3 yr) with idiopathic scoliosis took part in this study. In terms of location, thoracal scoliosis was dominant. Photogrammetry with automatic Moiré fringe analysis system was used to assess the spinal contour. Activity of the spinal flexors and extensors was tested isokinetically at 3 angular velocities: 60, 90 and 120°/s. The measured force-velocity parameters were analysed according to location of the scoliosis (primary thoracal or primary thoraco-lumbar scoliosis), the size of the deformity and posture type: lordotic, kyphotic or equivalent (balanced) (a posture type, where thoracic kyphosis and lumbar lordosis are of similar size – they are balanced).

Results and conclusions: A step-by-step discriminant analysis indicated that parameters associated with muscle endurance were the most diversified regardless of the division criterion applied. It was also revealed that functioning of the trunk muscles was related to the spine asymmetry in the frontal plane as well as on the spinal contour in the sagittal plane.
Strength of trunk and thigh musculature and bone mineral density in women aged 40–79 years
Authors: Skrzek Anna , Bolanowski Marek
Published: October 2018

Background: Decreased bone strength together with impaired physical efficiency followed by falls are the most important causes of osteoporotic fractures in elderly population.

Objectives: To examine the influence of age on isokinetic trunk and knee flexion and extension torque properties, and to study their associations with bone mineral density in women.

Material and methods: 288 women were divided into 4 age groups(40–49, 50–59, 60–69, 70–79 years). Isokinetic concentric studies of spinal and knee extensors and flexors were carried out at 90°/s and 120°/s, for spine, and 60°/s and 180°/s for knees. Bone mineral density was measured in the proximal femur by DXA.

Results: The different strength parameters (peak torque, peak torque/body mass, average torque of five repetitions) decreased and the time to reach peak torque increased with age. Some relations have been noted between these isokinetic parameters and bone mineral density.

Conclusions: Age-related deterioration in strength-velocity parameters of knee and spinal muscles are co-incidental with a gradual decrease in proximal femur BMD in older women.
Muscle strength and jumping distance during 10 years post ACL reconstruction
Authors: Nyberg Birgitta , Granhed Hans , Peterson Kerstin , Piros Christian , Svantesson Ulla
Published: October 2018

The aim of this study was to analyze long-term changes in muscle strength and jumping ability and to assess the relationship between these parameters after anterior cruciate ligament (ACL) reconstruction. Sixty-three patients (39 men) with a mean age of 30.3 years (range 19–42) who underwent an ACL reconstruction between 1990–1992 participated in the study. Quadriceps and hamstring isometric and isokinetic strength as well as one-leg hop test for distance were measured preoperatively and six months 1, 2, 3 and 10 years postoperatively. The injured leg was significantly weaker than the non-injured leg in knee extension strength on all test occasions and in knee flexion strength except at ten years. There was a strong correlation between the muscle strength tests at different speeds. The one leg hop for distance showed significant differences between the injured and non-injured leg on all test occasions. A moderate to high correlation was observed between muscle strength and jumping ability with higher values for the non-injured leg. In our study we found a persisting weakness in the quadriceps as well as jumping ability during ten years. This is an indication that it is hard to recover the preoperative functional level after an ACL reconstruction.
Data reproducibility of an inertial resistance exercise device suggested for use during space travel
Authors: Caruso J.F. , Williams J.A. , Hari P. , McCoy J.D. , Coday M.A. , Ramsey C.A. , Capps L.B.
Published: October 2018

An exercise ergometer that employs two flywheels for inertial resistance was created to abate ankle extensor mass and strength losses incurred with space flight. Unlike other flywheel- and inertia-based devices, the ergometer imparts muscle-lengthening resistance so that the ankle extensors may perform concentric and eccentric muscle actions within a single exercise repetition. Due to the unique manner the ergometer operates and the need to quantify workout data for the development of in-flight exercise protocols, instrumentation of the device is an important concern. After calculation of the flywheels' moment of inertia, a motor with a small rotary shaft and rubber wheel at its terminal end was mounted on the ergometer so that it stayed in contact with, and rotated concurrently with, a single flywheel. Voltage samples produced from changes in flywheel velocity were recorded on-line at 100 MHz. Exercise performance was assessed in healthy college-age subjects (n=34) across two workouts spaced one week apart. Workouts entailed two sets of ten seated calf press repetitions as subjects were instructed to exert maximal voluntary effort. Multiple test-retest measures revealed the inertial resistance ergometer, instrumented as described herein, elicits reproducible intra- and inter-workout performance data.
Effect of circadian rhythm of neuromuscular properties on muscle fatigue during concentric and eccentric isokinetic actions
Authors: Nicolas A. , Gauthier A. , Michaut A. , Davenne D.
Published: October 2018

This study was conducted to describe the time-of-day effect on muscle fatigue during both intermittent concentric (CE) and eccentric (EE) exercises. A second aim was to examine whether the time of day at which the exercise was performed influenced recovery of muscle strength. Ten male subjects performed CE and EE consisting of 5 sets of 10 maximal voluntary contractions (MVC) of the elbow flexors (angular velocity: 60°/s) at two different times (06:00 h and 18:00 h). Torque and Electromyographic activities (EMG) of the biceps brachii and triceps brachii were recorded before (Pre), during and immediately after (Post) each fatiguing task. Furthermore, strength recovery was measured 2 days(Post $_{2d})$ , 3 days (Post $_{3d})$ and 7 days (Post $_{7d})$ after each fatiguing task. Results showed that during CE, torque variations were greater at 18:00 h than at 06:00 h. No time-of-day effect occurred during EE. Recovery time was faster in the morning than in the evening for isometric MVC only. To conclude, unlike the case in eccentric mode, mechanisms involved in concentric muscle action appear to be time-of-day dependent, with a greater muscle capacity in the late afternoon. Also, strength recovery is greater when fatiguing exercises are performed in the early morning than in the late afternoon.
Reproducibility and estimation of muscular torque in athletes during maximal and submaximal efforts
Authors: Leverrier Céline , Molinaro Corinne , Gauthier Antoine
Published: October 2018

The purpose of this study was to assess the reproducibility and estimation of maximal (MVC) and submaximal muscular torque. Eight volunteers performed knee extension movements on a dynamometer. After one practice session, 3 test sessions were performed at 1 and 7 day intervals. At each session, subjects performed maximally and submaximally (25, 50 and 75% during isometric (45°) and concentric actions at 90 and 300°/s. The maximal muscular torques revealed no significant difference over the 3 test sessions. When estimating submaximal muscular torques, subjects correctly estimated torque percentages produced in the isometric action (except in the 75% MVC) and in dynamic action (except in the 90°/s, 25% MVC). As for the stability of these estimations, subjects corrected the error in concentric actions evidencing the possible involvement of efferent copy that could enable a comparison between actual and perceived performance. On the other hand, the error in isometric actions was maintained pointing out to very limited use of this contraction mode in sporting activities.
Isokinetic and electromyographic study of internal and external rotator muscles of tennis player
Authors: Julienne R. , Gauthier A. , Moussay S. , Davenne D.
Published: October 2018

The purpose of this study was to explore the effects of intensive tennis practice on the mechanical and electromyographic (EMG) activity of the external (ER) and internal (IR) rotators of the shoulder. Isokinetic and EMG testing of tennis (T, N=8) and control (C, N=8) subjects was performed using a CYBEX NORM. Shoulder rotation strength was measured at 5 angular velocities: concentric 60, 180, 300 and eccentric 60 and 180°/s during which peak torque(PT) and EMG activity of the infraspinatus (ER) and pectoralis major (IR) was recorded. For the T group dominant side (DS) the ER/IR ratio was lower than the non dominant side (NDS) whereas no such difference was observed between DS and NDS of C group. No ERecc/IRcon ratio difference was observed between sides and groups. ER co-activation in the T group was greater in the DS compared to the NDS and the DS of C group, while values were the same for both sides of C group. It therefore seems that tennis players present an adaptation to their activity. However their mechanical and EMG values deviate quite sharply from standard values which may potentially account for injury.
Differential effects of an acute bout of passive stretching on maximal voluntary torque and the rate of torque development of the calf muscle-tendon unit
Authors: Maisetti O. , Sastre J. , Lecompte J. , Portero P.
Published: October 2018

This study was aimed to examine the impact of acute stretching on the rate of force development (RFD) of the plantar flexors (PF). Eleven physically active female subjects participated in the study. The right calf muscle-tendon unit was stretched during five passive cyclic slow stretches(5°/s) that consisted of a dynamic ascending stretch phase to a pre-determined final joint angle (80% of maximal dorsiflexion angle) and a 15∼s hold phase. Maximal isometric torque (MVC) of PF and dorsiflexors (DF) and the RFD of PF were determined before, immediately and 30min following stretching. Changes in passive stiffness, passive resistive torque and torque relaxation of PF were computed during stretching. Passive characteristics decreased significantly during stretching (−11 to −27%, P<0.01). DF MVC did not change following stretching but there was a significant decrease in PF MVC immediately and after 30 min of recovery (−10%, P< 0.001). In contrast, PF RFD remained unaltered following stretching (P>0.05). These results indicate that passive stretching (< 5 min) can be applied without altering the capacity to develop torque rapidly under isometric condition up to 75% of MVC despite significant MVC impairment. These findings may have practical implications for stretching undertaken during rehabilitation or sport training.
Influence of post-trauma time on muscular balance of the shoulder in wheelchair athletes: A preliminary study
Authors: Denier Marielle , Gremeaux Vincent , Fattal Charles , Codine Philippe , Bernard Pierre Louis
Published: October 2018

Article without abstract.
Identification of mechanical consequences of jumper's knee by isokinetic concentric torque measurement in elite basketball players
Authors: Dauty Marc , Dupré Maryse , Potiron-Josse Michèle , Dubois Charles
Published: October 2018

Jumper's knee is a major reason of competition interruption for elite basketball players. This is due to the patellar tendinosis which explains knee pain and the decreased strength of knee extensors required for performing the jump. The aim of this study was to determine whether isokinetic parameters could identify competitive sportsmen who suffered from jumper's knee. The bilateral knee concentric strength of fifty seven elite basketball players was measured using a Cybex Norm isokinetic dynamometer at 60, 180 and 240°/s and during a longer test (15 × 180°/s). From this population, fifteen competitive basketball players with unilateral jumper's knee (Victorian Institute of Sport Assessment score: 62 ± 12) were compared with 42 control cases (VISA score: 93 ± 6). A knee extensors asymmetry at 60°/s of more than 10% identified the injured basketball players and represented the more useful parameter (probability of 66%). The fatigue isokinetic test at 180°/s was not informative. Injured athletes knee flexors strength was not different from the uninjured players. We conclude that concentric isokinetic evaluation of knee extensors at 60°/s indicate knee extensors torque asymmetry which may play a role in jumper's knee pathology.
Peripheral isokinetic muscle function and cardiorespiratory capacity in coronary artery disease patients
Authors: Elleuch M.H. , Ghroubi S. , Chaari M. , Elleuch H. , Massmoudi K. , Abdenadher M. , Trabelssi I. , Akrout M. , Feki H. , Frikha I. , Dammak J. , Kammoun S. , Zouari N.
Published: October 2018

Objective: The aim of this study was to determine if the diminished aerobic capacity of coronary artery disease (CAD) in male patients is accompanied by a peripheral impaired skeletal muscle function and to assess the correlation between the isokinetic strength and aerobic aptitude of these patients.

Materials and methods: Fifteen CAD patients and 15 healthy subjects(age: 60 ± 6 vs 57 ± 3.5 years old) performed both maximal exercise testing, an isokinetic assessment of knee muscles and a 6-minute walking test. The quadriceps and hamstrings were tested at 150 and 180°/s while being monitored with ECG. The cardio-respiratory and mechanical parameters (VO2, VT, HR, and power) were measured at ventilatory threshold and at maximal effort during a maximal exercise testing.

Results: Isokinetic assessment was conducted successfully with all patients. No rhythm irregularity or hemodynamic anomalies were observed in the 2 groups. Muscle testing revealed significant strength impairment. Quadriceps peak torque, at 150°/s was 77 ± 16 Nm in patients vs. 99 ± 23 Nm in controls, (p<0.01) while at 180°/s the values were 71 ± 14 vs. 91 ± 23 Nm, (p<0.01), respectively. For the hamstrings the values were respectively 49 ± 16 vs. 66 ± 14 Nm, (p <0.01) and 47± 10 vs. 60 ± 12 Nm, (p<0.01).

CAD subjects presented a deficient aerobic capacity compared to the healthy control group at maximal effort (Vo2 maximal uptake: Vo2 max: 20.34± 4.95 vs. 29.16 ± 7.68 ml mn $^{-1}$ kg $^{-1}$ , (p=0.01); maximal ventilation Ve max: 58.18 ± 16.28 vs 84 ± 24.45 ml mn ${-1}$ , (p<0.05); heart rate: HR max: 118 ± 21 vs 152 ± 13 beats mn $^{-1}$ , (p<0.001); maximal power: P max: 102 ± 31 vs. 153 ± 33 W. (p<0.001) and at ventilatory threshold: VT (Vo2: 13.77 ± 2.33 vs. 17.08 ± 3.59 ml mn $^{-1}$ kg $^{-1}$ , (p< 0.05); VE: 29.64± 6.64 vs. 37.76 ± 7.2 ml mn $^{-1}$ ,(p<0.05); HR: 86 ± 14 vs. 111 ± 15 beats mn $^{-1}$ , (p=0.001); but no significant difference was noticed for power (P: 61 ± 12 vs. 76 ± 24 W:). We also noticed that isokinetic muscle strength and O2 peak were not related to each other and are therefore independent.

Conclusion: This study shows that CAD patients, compared to healthy subjects, have impaired cardio respiratory capacities which are accompanied by increased muscle fatigability. Isokinetic muscle strength and maximal aerobic capacity are independent of each other. An isokinetic muscle assessment in these patients must be conducted systematically and seems to have a considerable value in cardiovascular rehabilitation.
Acute effect of percutaneous electrical stimulation of knee extensor muscles on isokinetic torque and power production performance
Authors: Requena B. , Gapeyeva H. , Ereline J. , Pääsuke M.
Published: October 2018

The aim of the present study was to examine the acute effect of a brief submaximal percutaneous electrical stimulation (PES) of the knee extensor(KE) muscles as a conditioning activity on the isokinetic peak torque (PT) and average power (AP). Eighteen male students aged 20–25 years performed maximal voluntary concentric isokinetic knee extensions at angular velocities of 60 and 180°/s in control (CON) trial (without prior PES application), followed by a PES trial after 30 min rest period. In PES trial, a conditioning submaximal (25% of the maximal voluntary isometric contraction force) isometric tetanic contraction of the KE muscles was induced by a 7 s direct PES at 100 Hz, interspersed after 3 min with testing of voluntary isokinetic performance. No significant differences in isokinetic knee extension PT and AP were observed between PES and CON trial at 60°/s. However, a significantly greater (p < 0.05) isokinetic PT (8.9%) and AP (8.2%) were observed in PES trial compared to CON trial at 180°/s. In conclusion, application of a brief high-frequency submaximal PES may enhance isokinetic strength and power of the KE at a moderate but not at a low angular velocity.
Association of strength with patellar tendinopathy in female runners
Authors: Krauss I. , Grau S. , Rombach S. , Janssen P. , Maiwald C. , Axmann D. , Horstmann T.
Published: October 2018

Muscle weakness and muscle imbalance may lead to musculotendinous injuries since the energy absorption capacity of the affected muscle tendon unit is reduced. The purpose of this study was to investigate the maximum strength and strength endurance of the thigh musculature in healthy female runners (F: n=26) and female runners suffering from patellar tendinopathy (PT: n=20).

Isokinetic strength measurements were recorded in a seated position. Primary outcome variables were maximum concentric and eccentric peak torque (at 60°/s) and concentric hamstrings-quadriceps-quotient (HQQ). Secondary outcome variables were relative peak torques [Nm/kilogram] and eccentric endurance quotient calculated as the ratio of muscle strength at the end of a 1-minute exercise compared to at the beginning of the exercise period.

The primary outcome variables were analyzed using Student's t-test for each measure(α = 0.05). Secondary outcome variables were qualified descriptively.

The results showed no statistically significant differences between injured and healthy female runners in concentric and eccentric peak torque or HQQ. Secondary outcome variables also failed to show inter-group differences. We therefore conclude that these variables are not relevant with respect to PT in female runners.
The reproducibility of an isokinetic testing technique at the ankle joint
Authors: Morrison Katherine E. , Kaminski Thomas W.
Published: October 2018

The purpose of this study was to determine the reproducibility of measurements derived from a plantar flexion and dorsiflexion isokinetic test protocol. Recreationally active men (n=8) and women(n=18) were seated in 30° of trunk flexion and full knee extension (0° of knee flexion) and performed three concentric and eccentric dorsiflexion and plantar flexion movements at the speeds of 30°/s and 120°/s on two different occasions. Peak torque (PT) and average torque (AT) measurements were obtained and compared across the two sessions. Intra-class correlation coefficient (ICC's) values indicated acceptable reproducibility for the concentric and eccentric PT and AT values of dorsiflexion (range from 0.77–0.93) and plantar flexion (range from 0.78–0.95). The corresponding Standard Error of Measurement (SEM) values indicated a good level of measurement precision. These findings suggest that this isokinetic test protocol involving an extended knee position for isolating PF and DF ankle motions produces reliable measurements. This test protocol offers a viable alternative to traditional test positions used to assess isokinetic strength in the ankle joint.
Assessment of gender differences in maximal anaerobic power by ratio scaling and allometric scaling
Authors: Hazir Tahir , Kosar Nazan Sukran
Published: October 2018

The purpose of this study was to determine gender differences in maximal anaerobic power by using both ratio scaling and allometric scaling. 27 males and 26 females voluntarily participated in this study. Wingate test was used to determine both peak power and mean power. Body weight, lean body mass and thigh muscle cross sectional area were determined anthropometrically. Males had significantly greater peak power and mean power in absolute terms, ratio-scaled and allometrically scaled to body weight, lean body mass and thigh muscle cross sectional area (p< 0.01) compared to females. The relationships between ratio-scaled anaerobic power indices and relevant body size descriptors were significantly different from zero(p< 0.05). Ratio scaling of anaerobic power indices did not create a dimensionless index as the relationships between ratio-scaled anaerobic power indices and relevant body size descriptors are different from zero. On the other hand, relationships between allometrically scaled anaerobic power indices and relevant body size descriptors approached to zero indicating more dimensionless index compared to ratio scaling. Therefore, allometric analysis should be considered as a method to account for the influence of body size in intergroup and gender comparisons of anaerobic power. Furthermore, we have found significant gender differences in allometrically normalized anaerobic power indicating that other factors in addition to body dimensions accounts for the gender differences in anaerobic power. This result suggests that no method is perfect in accounting for gender differences in anaerobic power and thus physical performance studies of males and females should be conducted seperately.
Reproducibility of isokinetic ankle dorsiflexor strength and fatigue measurements in healthy older subjects
Authors: Holmbäck Anna Maria , Lexell Jan
Published: October 2018

The aim of this study was to determine the test-retest (two occasions seven days part) reproducibility of isokinetic (Biodex) concentric(CON) and eccentric (ECC) ankle dorsiflexor strength and fatigue measurements in older subjects using several statistical methods. Thirty healthy men (n=15) and women (n=15) aged between 70 and 85 years participated in the study. To determine the reproducibility of strength measurements, the 30 individuals performed three maximal CON and ECC contractions at 30°/s and 90°/s. The intraclass correlation coefficient (ICC $_{2.1}$ ) for CON and ECC strength measurements was high and ranged from 0.94 to 0.98. Bland& Altman graphs and analyses indicted no systematic bias. The standard error of measurement (SEM), representing the smallest change that indicates a real improvement (or deterioration) for a group of individuals, was small(< 2.3 Nm). The smallest real difference (SRD), representing the smallest detectable change that indicates a real improvement (or deterioration) for a single subject, was also small ('error bands' from −7.2 Nm to 5.6 Nm). A high correlation (Pearson's r > 0.94) between CON peak torque at 30°/s and 90°/s, as well as ECC peak torque at 30°/s and 90°/s, suggested that any of these two velocities could be used as a reference. To determine the reproducibility of fatigue measurements, 28 of the 30 individuals performed 50 maximal CON contractions at 60°/s. Reproducibility of the loss in work (work fatigue) and the relative loss in peak torque, comparing the first three to the last three contractions (3-3), was determined and the ICC was 0.71 and 0.60, respectively. In addition, the SEM was small (< 8.4%) and the 'error bands' to define the SRD for a single subject were also small (from −23.5% to 24.5%). In conclusion, these values indicate small measurement errors and thus provide a clinically acceptable basis for testing ankle dorsiflexion strength and fatigue of the dominant side in healthy older people.
Effects of a non circular chainring on muscular, mechanical and physiological parameters during cycle ergometer tests
Authors: Horvais Nicolas , Samozino Pierre , Zameziati Karim , Hautier Christophe , Hintzy Frederique
Published: October 2018

This study analysed muscular, mechanical and physiological parameters using a circular chainring (CC) and a non circular Osymetric chainring (OC). OC was characterized by the use of a lower radius during top and bottom dead center and a higher radius during downstroke and upstroke phases.

Twelve triathletes performed (i) an 8 min submaximal test and (ii) two 8 s maximal sprint tests. Gross efficiency was calculated during the submaximal test. Instantaneous external force and pedalling rate were recorded and the instantaneous net crank torque was calculated during both tests. Lower limb muscles coordination pattern (timing and magnitude) were also recorded.

During the submaximal test, the only significant differences were the lower net crank torque of OC vs. CC at 0° and 180° and the higher net crank torque of OC vs. CC at 90° (P< 0.05). Concerning the sprint test, the only significant difference was the higher burst duration of the biceps femoris muscle with OC (P< 0.05).

Present results indicate that OC facilitated mechanically the foot path at 0° and 180°. Nevertheless, this mechanical effect did not seem to be sufficient to improve performance since the muscles coordination pattern was not modified.
Effects of high intensity running to fatigue on isokinetic muscular strength in endurance athletes
Authors: Denadai Benedito Sérgio , Greco Camila Coelho , Tufik Sergio , de Mello Marco Túlio
Published: October 2018

The objective of this study was to examine the effects of high intensity exhaustive running exercise on the muscular torque capacity of the knee extensors for two types of contraction (concentric and eccentric) at different angular velocities (60 and 180°/s) in well-trained runners. Eleven male runners specialized in middle and long-distance running volunteered to participate in this study. Initially each subject performed, on different days, two familiarization sessions on an isokinetic dynamometer and an incremental treadmill test to volitional exhaustion to determine the velocity associated with the onset of blood lactate accumulation (OBLA). The subjects then returned to the laboratory on two occasions, separated by at least seven days, to perform maximal isokinetic knee contractions at each of the velocities under eccentric (Ecc) and concentric(Con) conditions. Conducted randomly, one test was performed after a standardized warm-up period of 5 min at 50% VO $_2$ max. The other test was performed 15 min after continuous running at OBLA until volitional exhaustion. Following this high intensity exercise there was a significant reduction of Con at 60°/s and a significant reduction of Ecc at both velocities. Percent strength losses after running exercise were significantly different between contraction types only at 180°/s. We can conclude that the reduction in isokinetic peak torque of the knee extensors after a session of high intensity exhaustive running exercise at OBLA depends on the contraction type and angular velocity.
Quadriceps strength loss at flexed knee angles in active high-level soccer players with patellofemoral pain
Authors: Olmo J. , Aguado J.P. , Cortés L. , Espiniella A. , Morate F.
Published: October 2018

Patellofemoral pain (PFP) appears in actions that increase patellofemoral compressive forces such as forceful quadriceps contraction in a flexed knee position. PFP has been associated with quadriceps strength decrease and disturbances ('breaks') in the torque-angular position. Twenty two active high-level soccer players with PFP and breaks in the quadriceps isokinetic curve were studied. The results showed that the quadriceps strength was significantly reduced in comparison with the uninvolved side, being more affected at flexed angles of the knee. A single break in the quadriceps torque-angular position curve started on average at 73 ± 7° reaching the maximum break at 65 ± 7° and recovering at 54 ± 9°. At the minimal within-break torque angle the average reduction was 30.6% while the PT was reduced by 18.4%. Sub-clinical PFP in high-level soccer players may be related to a significant loss in quadriceps muscular performance in the first part of knee extension possibly affecting common soccer tasks such as kicking, jumping or tackling. Isokinetic concentric testing may be used to detect and characterize this alteration.