Cybex Norm Research Articles

Intramachine and intermachine reproducibility of concentric performance: A study of the Con-Trex MJ and the Cybex Norm dynamometers

Introduction: There is minimal information in the literature concerning the intramachine reliability of the new Isokinetic dynamometer Con-Trex MJ, and the intermachine reproducibility of this instrument with the Cybex Norm isokinetic dynamometer. Objective: The purpose of this study was to provide some insight with regard to the reproducibility of Con-Trex MJ in measuring the knee muscle performance in flexion and extension (concentric) and to compare the variability of measurement between Con-Trex and Cybex Norm. Methods: 35 (70 legs) male subjects with no previous history of any knee pathology volunteered for the study. Intramachine reproducibility was evaluated by assessing 30 legs twice on the Con-Trex MJ, within 2 to 7 days, at angular velocities of 60 ◦ , 180 ◦ and 300 ◦ /sec. Intermachine reproducibility was evaluated by assessing 40 legs randomly on the Con-Trex MJ and Cybex Norm within 2 to 7 days at 60 ◦ and 180 ◦ /sec. Coefficient of variation (CV) was used to determine the reproducibility of repeated measurements at p< 0.01. Results: Intra: The variability of measurements of Con-Trex for Peak Torque, was 5.19-5.68% for extension and 4.84-7.33% for flexion depending on the angular velocity. This is acceptable for clinical and research studies. Inter: Between the two Isokinetic devices there was a greater CV for Peak Torque ranging 7.28-9.17% for extension and 8.54-15.84% for flexion. Conclusion: Based on the results of the present study, comparisons of results between the two devices may not be valid. The results for knee flexion and extension measurements at 60 ◦ and 180 ◦ /sec recorded with Con-Trex were consistently greater than the values recorded with the Cybex Norm.

Linkage of myostatin pathway genes with knee strength in humans.

This study was the first to explore the potential role of the myostatin (GDF8) pathway in relation to muscle strength and estimated muscle cross-sectional area in humans using linkage analysis with a candidate gene approach. In young male sibs (n = 329) 11 polymorphic markers in or near 10 candidate genes from the myostatin pathway were genotyped. Muscle mass was estimated by anthropometric measurements, and maximal knee strength was evaluated using isokinetic dynamometers (Cybex NORM). Single-point nonparametric variance components and linear quantitative trait locus regression linkage analysis methods were used. Linkage patterns were observed between knee extension and flexion peak torque with markers D2S118 (GDF8), D6S1051 (CDKN1A), and D11S4138 (MYOD1), and a maximum LOD score of 2.63 (P = 0.0002) was observed with D2S118. The ratios of peak torque over muscle and bone area of the midthigh of the lower contraction velocity (60 degrees/s) showed more frequently significant LOD scores than the torques at high velocity (240 degrees/s). Although myostatin is physiologically more related to muscle mass through possible effects of hyperplasia and hypertrophy than it is to strength, only two estimated muscle cross-sectional areas were marginally linked (LOD 1.06 and 1.07, P = 0.01) with marker D2S118 near GDF8 (2q32.2). The present results gave suggestive evidence that the myostatin pathway might be important for strength phenotypes, and GDF8, CDKN1A, and MYOD1 are potential candidate regions for a further and denser mapping with respect to these phenotypes.

Corrélations et différences de performance entre des footballeurs, professionnels, en formation et amateurs à partir du test de sprint (10 mètres départ arrêté) et de tests isocinétiques du genou

Objective. – To study differences between professional soccer players, young players and amateur players for sprint test and knee isokinetic assessment. Method. – Ten professional players (Ligue 1) (24.4 ± 3.5 years) were compared with 13 young players (national-level) (20.7 ± 1.3 years) and 11 amateur players (regional-level) (24.3 ± 3.7 years). The 10-m sprint test was measured with photoelectric cells and isokinetic tests were carried out in a concentric action at 60 and 180 deg/s and in an eccentric action for flexors at 60 deg/s (Cybex Norm). The comparisons were realized by using an ANOVA test and the correlations were established with a Spearman test. Results. – Amateur soccer players run significantly more slowly than young and professional players ( P < 0.001). Significant correlations between sprint test, age and extensor torque reported to the body weight at 180 deg/s are found. Flexors torque and concentric ratio hamstring-to-quadriceps are comparable whatever sports level. On the other hand, a flexors asymmetry is shown in professional soccer players. The dominant leg and the playing position do not influence this result. Conclusion. – According to isokinetic parameters and the 10-m sprint studied, young soccer players and professional soccer players present athletic performances superior to those of the amateurs. These decrease with the age, whatever sports level.

Sex differences in isokinetic strength and power of knee muscles in 10–12 year old swimmers

The aim of the study was to determine knee muscles absolute and relative strength and power, as well as flexor/extensor (F/E) ratios, in prepubescent male and female swimmers, during concentric isokinetic testing. Twenty boys and 20 girls, aged 10-12 years, participated in this study. Gravity corrected concentric isokinetic peak torque (strength) and average power (power) were measured by a Cybex Norm dynamometer at the angular velocities of 60, 120 and 180 ◦ /s, during unilateral knee extensions and flexions. The relative values of strength and power were expressed per kilogram of lean body mass. Knee extensors strength and power do not differ significantly between boys and girls at the angular velocities of 60 and 120 ◦ /s. In contrast, at the higher angular velocity of 180 ◦ /s boys exerted greater values than girls ( p< 0.01). With respect to the knee flexors, boys exerted greater values than girls only at the angular velocities of 120 and 180 ◦ /s ( p< 0.01). When relative strength and relative power were calculated, no significant differences existed between boys and girls for both muscle groups. Moreover, the shapes of strength-velocity and power-velocity curves, as well as knee F/E ratios, were similar for both groups.

Effects of Physioball and Conventional Floor Exercises on Early Phase Adaptations in Back and Abdominal Core Stability and Balance in Women

The purpose of this study was to compare the effects of 5 weeks of physioball core stability and balance exercises with conventional floor exercises in women. The experimental group (n = 15) performed curl-ups and back extensions on the physioball while the control group (n = 15) performed the same exercises on the floor. Baseline and post-training tests included electromyography (EMG) recordings of the rectus abdominus and erector spinae muscles; abdominal, back, and knee strength measurements with the Cybex Norm System; and 2 unilateral stance balance tests. The physioball group was found to have significantly greater mean change in EMG flexion and extension activity (p = 0.04 and p = 0.01, respectively) and greater balance scores (p < 0.01) than the floor exercise group. No significant changes (p > 0.05) were observed for heart rate or Cybex strength measurements. Early adaptations in a short-term core exercise program using the physioball resulted in greater gains in torso balance and EMG neuronal activity in previously untrained women when compared to performing exercises on the floor.

Identification of previous hamstring muscle injury by isokinetic concentric and eccentric torque measurement in elite soccer player

Twenty-eight elite soccer players (23 years ± 3.3; 74 kg ± 7.5; 178 cm ± 6.5) were tested to find out whether isokinetic parameters could identify sportsmen who had previously suffered from hamstring muscle injury. Eleven players with 15 previous moderate or major hamstring muscle injuries in the preceding 2 years were compared with 17 controls. Strength was measured using a Cybex Norm isokinetic dynamometer on a concentric and eccentric contraction at the angular speed of 60°/s. An ipsilateral concentric Hamstring-to-Quadriceps ratio lower than 0.6 and an eccentric hamstring asymmetry of more than 10% did not enable identification of soccer players with previous hamstring muscle injury. On the other hand, concentric hamstring torque asymmetry of more than 10% identified the uninjured soccer players (probability of 90.1%). A dynamic control ratio (eccentric hamstring-to-concentric quadriceps) lower than 0.6 provided the best predictor of previous hamstring muscle injury (probability of 77.5%). In conclusion, concentric and eccentric isokinetic evaluation of hamstring muscle at the speed of 60°/s renders the search for previous hamstring muscle injury possible by revealing muscle torque asymmetry, which persists despite the resumption of competitive soccer.

Reproducibility of concentric and eccentric isokinetic strength of the shoulder rotators in normal subjects 40 to 55 years old

The purpose of this study was to define the test-retest reproducibility of concentric and eccentric isokinetic measurements of shoulder rotators. It was carried out at a 26 day ±4 interval. Fourteen healthy volunteer subjects (7 men and 7 women), aged between 40 and 55 years (47.5 ± 5.6 years), were included. Evaluation was carried out with a Cybex Norm dynamometer and the reliability was calculated according to the intra-class correlation coefficient (ICC 2. 1). The protocol was randomised for the shoulder and for sets of concentric (con) and eccentric (ecc) tests. Concentric sets consisted of 5 movements of internal (IR) and external rotation (ER) at the speed of 60°/sec. then 120°/sec. Eccentric performance was recorded only for the external rotators, to determine the ratio ER ecc /IR con . Results indicated excellent reproducibility for the peak torque (0.91-0.98), total work (0.88-0.96) and average power (0.83-0.94) in concentric muscle action for internal and external rotators and in eccentric muscle action for external rotators at 60 and 120°/sec. On the other hand the strength ratio: ER con /IR con and ER ecc /IR con should be interpreted with caution because of a lower reproducibility (ICC: 0.53-0.83). In conclusion, isokinetic findings relating to concentric and eccentric performance of the internal and external rotators of the shoulder are reproducible under the present protocol. These findings may serve for assessing rotator cuff function at the age where the incidence of rotator cuff overuse becomes a serious problem.

Aptitudes cardiorespiratoires et fonction musculaire périphérique chez des patients coronariens

Objective. – The aim of this study is to determine if the diminished aerobic capacity of coronary artery disease patients is accompanied by a impaired peripheral skeletal muscle function compared to healthy control subjects. Methods. – Thirteen coronary patients and 9 healthy control subjects (57 ± 7 vs 55 ± 8 years) have realised both a maximal laboratory exercise testing and an assessment of the peripheral skeletal muscle function on a isokinetic apparatus (Cybex Norm II). The cardiorespiratory and mechanical parameters (VO 2 uptake, VE, HR and Power output) were measured at ventilatory threshold and maximal effort during a cycloergometer testing. The peripheral skeletal muscle function of the quadriceps was assessed from the maximal voluntary isometric force (MVIF) and from static endurance time (SET) at an intensity of 50% of the MVIF. Results. – Coronary patients showed a diminished aerobic capacity at maximal effort (VO 2max: 23.56 ± 8.1 vs 42.43 ± 9.74 ml min –1 kg –1, p < 0.0001; VE max: 67.07 ± 16.85 vs 90.15 ± 20.76 l min –1, p < 0.01; HR max: 110 ± 17 vs 153 ± 20 beats min –1, p < 0.0001; P max: 133 ± 40 vs 233 ± 39 W, p < 0,001) but also at ventilatory threshold (VO 2: 15.81 ± 5.7 vs 29.61 ± 7.8 ml min –1 kg –1, p < 0.001; HR: 92±11 vs 135±21 beats.min –1, p < 0.0001, P: 88 ± 32 vs 153 ± 39 W, p < 0.001) except for VE (VE: 38.98 ± 9.91 vs 46.68 ± 7.03 l min –1, NS). No difference was found between the MVIF (MVIF: 230 ± 46 vs 228 ± 21 N m –1, NS) between coronary patients and control subjects whereas the SET is lower in coronary patients (65 ± 19 vs 88 ± 9 s, p < 0.003). Conclusion. – Coronary artery disease patients have a lower aerobic capacity accompanied by a impaired peripheral skeletal muscle function.

Comparative study of two isokinetics dynamometers: CYBEX NORM vs CON-TREX MJ

In the majority of peripheral joints (ankle, knee, hip, elbow, wrist . . . ), the contraction of a muscular group produces a circular movement of the bony lever around the center of rotation represented by the joint. In 1967, Hislop end Perrine [6] invented the first isokinetic dynamometer which is dedicated to quantify the force moment (or torque) express by the contraction of a muscular group during a circular movement. Today, the market is shared between several constructors. Nevertheless, even if their vocation is to quantify a force movement, users are often disappointed by not being able to reproduce values between two machines. Differences of the subjects installation may be an explanation for those gaps [5,7]. CYBEX NORM and CON-TREX MJ are two isokinetic dynamometers distributed throughout the world. Thanks to their technical possibilities, they can deal with maximal intensity measurements in high level sportsmen [1,2,7] as well as with the very weak intensities you find in patients affected with spasticity [3,4, 11]. The purpose of this study is three-fold:

Shoulder isokinetic exploration following shoulder rotator cuff suture

Shoulder isokinetic exploration following shoulder rotator cuff suture J. Bineta, B. Forthommeb, J.P. Bierlairea, P. Meuranta, J.M. Crielaardb and J.L. Croisierb Department of Physical Medicine and Rehabilitation, CHR, Tournai, Belgium Department of Physical Medicine and Rehabilitation, CHU Sart Tilman, Li ege, Belgium The rotator cuff lesion is the most common shoulder pathology. After a well-achieved rehabilitation program of a few months, our patients’ mobility recovery is most of the time complete. The goal of this study is to evaluate the muscle strength at the end of the rehabilitation. The follow-up deals with 42 cases operated by two surgeons. Three surgical techniques were used: simple suture (3 cases), cuff-to-bone reinsertion (5 cases) and anchoring technique (34 cases). Six to eight months after the operation, the patients underwent a standard clinical examination and an isokinetic exploration (Cybex Norm) measuring the internal and external rotators and the abductors-adductors peak torques. As far as the rotators are concerned, this occurred according to the following criteria: patient lying supine, arm abducted to 90 degrees in the frontal plane (the engine rotating axis matches with the gleno-humeral joint centre). Three speeds were taken into account: 60, 120 and 240 degrees per second respectively repeated 3, 4 and 5 times (rest period between each set is 1 minute). As far as the abductors-adductors are concerned, this occurred according to the following criteria: patient lying on his/her side, dynamometer behind the patient, against rest put on the distal part of the arm, amplitude purposely ranging from 0 to maximum 90 degrees of abduction. Two speeds were taken into account: 60 and 180 degrees per second respectively repeated 3 and 4 times. Student’s T-test and correlation studies were carried out to statistically analyze the range of motion, the peak torques (absolute and relative values) and the ratios of the joint. From the point of view of strength when comparing at low speed to the non-operated arm, men showed a deficiency as high as 16% for the external rotators (Fig. 1), 6% for the internal rotators, 21% for the abductors (Fig. 2) and 7% for the adductors. Women’s deficiency turned out to reach 21% for the external rotators (Fig. 1), 5% for the internal rotators, 23% for the abductors (Fig. 2) and 10% for the adductors. Dominant-side is of paramount importance in strength recovery. The biggest difference is to be noticed on the internal rotators showing an 18% deficiency in patients operated on the non-dominant side whereas the dominant-side operated patients did not show any deficiency. Comparing dominant-side operated to non-operated sedentary men showed a weakening of 15% for the external rotators (very significant) at low speed affecting the ratio and diminishing of the abductor-adductor torque of 26% for the abductors and 20% for the adductors. When considering female patients, the same comparison at low speed showed a deficiency as high as 34% for the external rotators, 28% for the abductors and 36% for the adductors. In the group of non-dominant side operated patients, we found a correlation between external rotators deficiency at a speed of 240 degrees per second and preoperative pain for more than six months. Male patients showed a full recovery of the range of motion and female patients showed an external rotation deficiency as high as 5% (significant) whereas the internal rotation deficiency reached 10% (very significant). ISSN 0959-3020/03/$8.00  2003 – IOS Press. All rights reserved 56 J. Binet et al. / Abstract 0,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00 Operated Non-Operated Men Women Non-Operated

Study of EMG patterns and muscle strength in asymptomatic volunteers during isokinetic flexion-extension movement of the trunk

Study of EMG patterns and muscle strength in asymptomatic volunteers during isokinetic flexion-extension movement of the trunk P.-M. Dugaillya,b,c,, D. Mourauxa,b, N. Mangena, E. Brassinnea,b and P. Kleinb,c Department of Physical Therapy and Rehabilitation, Erasmus Hospital, Brussels, Belgium School of Physiotherapy and Rehabilitation, Universit e Libre de Bruxelles, Brussels, Belgium Research Unit on Manual Therapies, Universite Libre de Bruxelles, Brussels, Belgium Introduction: The objective of our study was to assess concentric muscle strength during flexion and extension of the trunk using an isokinetic device combined with analysis of back and pelvic muscle activities. Methods: Forty-one healthy volunteers, 21 females and 20 males (age: 25 ± 2 years; weight: 79 ± 8 kg; 178 ± 6 cm) participated in the study. They had no history of back or hip injuries. All subjects were familiar with concentric isokinetic back movements. Before the evaluation, the subject achieved a 10-minute bicycle warm-up and four pretest contractions. The assessment session consisted of 3 and 5 maximal concentric contractions during trunk flexion-extension at 30 ◦/sec and 120◦/sec, respectively. The entire session was performed for 2 different ranges of motion, 45 and 75 degrees. All tests were accomplished using an isokinetic dynamometer (CYBEX NORM). All electrical activities of paraspinal (PS) and gluteus maximus (GM) muscles were recorded from surface electrodes (O = 9 mm) bilaterally using a standard surface EMG procedure. Electrodes were positioned over the PS muscles at L5S1 spinal levels and over the GM at the sacrospinous ligament level. EMG data and torque were sampled at 1000 Hz and recorded using Noraxon Myosystem Software. All EMG signals were rectified and smoothed (RMS 50). All data were collected every 5 degrees from 0 degree to maximal range. Statistical analysis: Control of distribution and homogeneity of variances was conducted using Kolmogorov-Smirnoff and Levene tests. Influence of gender, velocity, movement and motion range on outcome measurements was analyzed using multivariate analysis of variance (ANOVA). Results: For each velocity males achieved significantly larger extension or flexion torque than females (p 0.05). In general, total ROM and velocity significantly influenced agonist EMG activity (p 0.89). During extension EMG recruitment patterns showed that PS and GM displayed peak activity for around 15◦ of trunk flexion while peak torque occurred around 35◦ and 65◦ for 45◦ and 75◦ ROM, respectively, at the lower speed. This observation was similar for males and females. Figure 1 illustrates torque intensity and EMG activities during flexion and extension over a 45◦ range of motion at 30◦/s ISSN 0959-3020/03/$8.00  2003 – IOS Press. All rights reserved 66 P.-M. Dugailly et al. / Abstract

Isokinetic dynamometry and electromyographic activity (sEMG) after anterior cruciate ligament reconstruction using semitendinosus and gracilis tendon autografts

Isokinetic dynamometry and electromyographic activity (sEMG) after anterior cruciate ligament reconstruction using semitendinosus and gracilis tendon autografts D. Mourauxa, P.-M. Dugaillya, E. Brassinnea and M. Vancabekeb Department of Physical Therapy and Rehabilitation, Erasmus Hospital, ULB, Brussels, Belgium Department of Orthopaedics Surgery, Brugmann Hospital, Brussels, Belgium Introduction: Quadriceps weakness after injury and reconstruction of anterior cruciate ligament (ACL) is well documented. This amyotrophy in the immediate postoperative period is related to several factors, such as decreased weight bearing, knee joint effusion, pain, harvesting of the tendon graft and neuromuscular factors [1]. The present study is designed to compare the short outcome of strength and EMG recruitment pattern of quadriceps and hamstring between 3 months postoperatively for an ACL reconstruction with hamstring tendon autografts fixed patients and a healthy control group. Methods: Thirteen healthy male students (mean age: 24 years, weight: 77 kg, height: 181 cm) participated in the study. They had no history of knee or hip injuries. They were compared to 19 patients (mean age: 31 years, weight: 80 kg, height: 180 cm) who had surgery for ACL reconstruction with hamstring tendon autografts precisely 3 months before these assessments. Patients were excluded if there were any other lesions in the same knee. In both groups the subjects were recreational athletes. All subjects were familiarized with isokinetic movements in concentric (CON) or ecTable 1 Mean ± standard deviation of quadriceps and hamstrings Peak Torque (PT). Comparison between control legs and UninvolvedInvolved legs. ∗Significant at p < 0.05 level Control Uninvolved Involved Quad PT Con 180◦/s 136 ± 23 125 ± 37 93 ± 28∗ Quad PT Con 60◦/s 193 ± 30 183 ± 30 118 ± 47∗ Ham PT Con 180◦/s 101 ± 16 89 ± 30∗ 85 ± 9∗ Ham PT Con 60◦/s 137 ± 18 118 ± 22∗ 101 ± 33∗ Ham PT Ecc 30◦/s 178 ± 13 146 ± 20∗ 113 ± 10∗ centric (ECC) contraction. The tests were performed with a CYBEX NORM consisting in 3 maximal dynamic contractions at 180◦/s and 60◦/s in CON (for both flexor and quadriceps muscles) and at 30◦/s in ECC (for flexor). During these tests, the sEMG activity was recorded from the vastus lateralis (VL), the vastus medialis (VM) the rectus femoris (RF) and the mass of the hamstring by the Noraxon Myosystem 2000. The exercices were performed at a range of motion from 0◦ to 105◦. All electrical activities were expressed in microvolt (μV). Influence of independent variables was analysed using multivariate analysis of variance

Proposal for the assessment protocols for different shoulder muscle groups

Isokinetic dynamometers allow an accurate measurement of the strength developed by muscle groups surrounding different joints. Nevertheless, the particular shoulder complexity offers a great variety of testing positions and articular planes for the isokinetic examiners. Consequently, users must define valid protocols and determine the reproducibility of the main parameters. Because shoulder dysfunctions frequently affect the rotator cuff muscles, our study aimed at the elaboration of a reliable isokinetic assessment for the internal (IR) and external (ER) rotators and for the abductors (ABD) and adductors (ADD) in healthy subjects. Ten male and ten female subjects (average age respectively 42 ± 5 years and 40 ± 4 years) without history of shoulder pathology participated in the study. Shoulder IR and ER were assessed using a Cybex Norm dynamometer in 90 ◦ of abduction in the frontal plane, the subject being in a lying supine position, at 2 angular velocities (60 ◦ .s −1 , 240 ◦ .s −1 ) in the concentric mode. In order to avoid the elevation of glenohumeral joint and elbow flexion during classical assessment, we proposed an original position and adapted protocol for ABD and ADD muscles. The subject was in lying lateral position, arm in the frontal plane, with a range of motion limited to 90 ◦ of abduction. Great care was taken to correctly align the glenohumeral center joint with the dynamometer axis. The new protocol proposed two speeds in the concentric mode (60 ◦ .s −1 and 180 ◦ .s −1 ). For the reproducibility study, an interval of 10 days was inserted between the two sessions of measurement.

Isokinetic assessment of knee flexors and extensors in professional soccer players

Isokinetic assessment of knee flexors and extensors in professional soccer players J.L. Croisiera, V. Reveillona, J.M. Ferretb, T. Cotteb, M. Gentyc, N. Popovichd, Mohty Filhoe, J.E. Faryniuke, S. Ganteaumea and J.M. Crielaarda Department of Physical Medicine and Rehabilitation, CHU Sart Tilman, Liege, Belgium Center of Sports Medicine, Lyon-Gerland, France Center La Roseraie, St Adresse, France Standard de Liege football Club, Liege, Belgium Tuiuti of Parana University, Curitiba, Brazil Muscle injuries are among the most common insults in soccer players and result from multifactorial origins. In recent studies [1,2], we focused on hamstring muscle strains because of the high frequency of re-injury and persistent complaints after return to athletic activities. This study attempted to define the thigh muscle profile in professional soccers and to identify preseason isokinetic strength variables as predictors of hamstring muscle strain. Seventy-seven professional soccer players (age: 26 ± 4 years, weight: 76 ± 5 kg, height: 180 ± 5 cm) recruited from 4 elite teams (in Belgium, Brazil and France) were included in the study. All the participating Centers used a Cybex Norm dynamometer and a standardized preseason isokinetic protocol consisting in concentric exertions (angular speeds of 60 deg/sec and 240 deg/sec) of both knee flexor and quadriceps muscles; afterward, flexors were subjected to eccentric angular speeds of 30 deg/sec and 120 deg/sec. The nature of muscle abnormalities was determined using statistically selected cutoffs: bilateral differences of 15% or more, concentric ratio less than 0.47, and mixed ratio (eccentric flexors / concentric quadriceps) less than 0.80. Thereafter, players were observed for 9 months and we recorded the severity and frequency of new hamstring muscle injuries throughout the subsequent competitive season. Focusing on the quadriceps in the concentric mode at 60 deg/sec, the whole group of players averaged 3.03 (± 0.42) N.m/kg, with a 7% difference between extreme team values. Flexors in eccentric at 30 deg/sec reached on average 2.32 (± 0.64) N.m/kg, with a 34% difference between extreme team results. Referring to the selected limits, 55% of the whole group of players were isokinetically imbalanced and result analysis confirmed the discriminating character of the eccentric trial and the specificity of the original mixed ratio [2]. During the longitudinal follow-up, seven players sustained clinically diagnosed hamstring muscle injuries that caused them to miss playing time (more than 4 weeks). Among them, six presented isokinetic preseason abnormalities. These results allow us to fix the risk factor of hamstring injury at: – 15% in the presence of strength imbalance (6 injuries in 41 imbalanced players), – only 3% in the absence of strength abnormality (1 injury in 36 normal players). Soccer players were isokinetically characterized by a great interindividual variability of flexor and extensor muscle performances. Assuming the multifactorial origin of muscular injuries, we emphasize the importance of strength imbalances as a major risk factor. Soccers with imbalances appeared 5 times more likely to sustain a hamstring strain than those without the imbalance. Consequently, preseason isokinetic assessment may allow a preventive approach of that problem. ISSN 0959-3020/03/$8.00  2003 – IOS Press. All rights reserved 62 J.L. Croisier et al. / Abstract

Test-retest reliability of an isokinetic muscle endurance test

The purpose of this study was to investigate the test-retest reliability of an isokinetic muscle endurance test. The right legs of twelve healthy males were tested on the Cybex Norm isokinetic dynamometer. The protocol consisted of 40 consecutive concentric knee extensions and flexions, performed maximally at an angular velocity of 120°/s. The subjects performed the test twice, five days apart. Total work, endurance ratio, 50% fatigue work, 50% fatigue time and 50% fatigue repetitions were obtained. A one-way analysis of variance (ANOVA) with repeated measures was used to examine the differences between test and retest values. The reliability coefficient was also established using the ANOVA results. The results indicated that measurements demonstrated high reliability (r > 0.819). It could be concluded that the protocol used in the present study can be used to evaluate muscle endurance.

레슬링 선수들의 단기간 체중감량이 슬관절의 등속성 운동능력에 미치는 영향

본 연구는 고교 레슬링선수들의 단기간 체중감량에 따른 등속성 운동능력 중 다리의 peak torque, peak torque %BW, total work, total work %BW, endurance ratio에 대한 변화를 알아보기 위하여 자기 체중에서 체중감량이 없는 집단 7명, 5%이상 감량집단 7명을 대상으로 체중감량 전ㆍ후를 측정하여 얻은 결론은 다음과 같다. 1. Peak Torque의 변화. 굴근의 경우 5%이상 감량 집단의 <TEX>$60^{\circ}C$</TEX>sec, <TEX>$90^{\circ}C$</TEX>/sec에서 유의하게 감소하였다. 그리고 신근의 경우 5%이상 감량 집단의 <TEX>$60^{\circ}C$</TEX>/sec, <TEX>$90^{\circ}C$</TEX>/sec, <TEX>$250^{\circ}C$</TEX>/sec에서 모두 유의하게 감소하였다. 2. Peak Torque %BW의 변화. 굴근의 경우 5%이상 감량 집단의 60<TEX>$^{\circ}$</TEX>/sec, 90<TEX>$^{\circ}$</TEX>/sec, <TEX>$150^{\circ}C$</TEX>/sec에서 모두 유의하게 감소하였다. 그리고 신근의 경우 5%이상 감량 집단의 <TEX>$90^{\circ}C$</TEX>/sec와 <TEX>$250^{\circ}C$</TEX>/sec에서 유의하게 감소하였다. 3. Total Work의 변화. 굴근의 경우 5%이상 감량 집단의 <TEX>$60^{\circ}C$</TEX>/sec,<TEX>$90^{\circ}C$</TEX>/sec에서 유의하게 감소하였다. 그리고 신근의 경우 5%이상 감량집단의 <TEX>$50^{\circ}C$</TEX>/sec, <TEX>$90^{\circ}C$</TEX>/sec. <TEX>$250^{\circ}C$</TEX>/sec에서 모두 유의하게 감소하였다. 4. Total work %BW의 변화. 굴근의 경우 5%이상 감량 집단의 <TEX>$60^{\circ}C$</TEX>/sec, <TEX>$90^{\circ}C$</TEX>/sec, <TEX>$250^{\circ}C$</TEX>/sec에서 유의하게 감소하였다. 그리고 신근의 경우 5%이상 감량 집단의 <TEX>$50^{\circ}C$</TEX>/sec, <TEX>$90^{\circ}C$</TEX>/sec, <TEX>$250^{\circ}C$</TEX>/sec에서 모두 유의하게 감소하였다. 5. Endurance Ratio의 변화. 굴근과 신근의 경우 두 집단 모두 유의한 차이가 없었다. 단기간의 무리한 체중감량은 근력, 근지구력의 저하로 경기력을 저하시킬 뿐만 아니라 건강을 해칠 우려가 있기 때문에 단기간의 무리한 감량이 되지 않도록 과학적이고 체계적인 체중관리가 이루어져야 할 것으로 사료된다. The purpose of this study is to investigate isokinetic strength changes of knee joint in accordance with short-term weight loss of wrestlers. For this purpose, 14 male wrestlers of a K technical high school in B city participated in our research. The wrestlers were divided into two groups; one group of the wrestlers didn't lose any weight, and the other lost over 5% of their weights. The isokinetic strength was also observed before and after weight loss. The isokinetic strenght test were processed at test speed of the<TEX>$60^{\circ}C$</TEX>/sec, <TEX>$90^{\circ}C$</TEX>/sec, and <TEX>$250^{\circ}C$</TEX>/sec with the CYBEX NORM system(Cybex 770＋TMS, USA). Peak torque, peak torque %BW, total work, total work %BW, and endurance ratio were measured. Results showed that the isokinetic strength after the short-term weight loss of wrestlers decreased meaningfully Although endurance ratio didn't show any meaningful difference in our research, but more accurate research may find out the relationship between short-term weight loss and the endurance ratio of isokinetic strength.

The relationship between jumping performance and isokinetic strength of hip and knee extensors and ankle plantar flexors

The purpose of this study was to examine the relationship between vertical jumping performance and isokinetic moment of force of knee extensors, hip extensors and ankle plantar flexors in adult males. Twenty-nine males performed squat and counter movement jumps on an Egrojump device. The peak jumping height and the total work (height x body mass) were used as indicators of vertical jump performance. The subjects also performed three submaximal and three maximal isokinetic efforts of the hip extensors, knee extensors and ankle plantarflexors at angular velocities of 60, 120 and 180°.s -1 on Cybex Norm Dynamometer. Pearson's product correlation tests indicated that there was a significant (p 0.05). Multiple regression analysis indicated that linear combinations of isokinetic torques accounted for 38% and 42% of the countermovement and squat jumping height variance, respectively. In contrast, regression models using isokinetic torques could predict jumping work accounting for 75% (counter movement jump) and 69% (squat jump) of the variance. The above results indicate that there is a moderate to high relationship between isokinetic knee and hip extension torques and vertical jump performance parameters, especially when jumping height is multiplied by subject's body weight. Furthermore, it appears that when using a linear combination of isokinetic torques from hip and knee joint muscle groups the multiple relationship between isokinetic tests and jumping performance is higher.

Computerized dinamometry as a method of evaluation of muscle strength of boys and girls of different maturational stages

O objetivo deste estudo foi descrever e comparar a força muscular isométrica e isocinética em meninos e meninas de diferentes graus maturacionais. Participaram do estudo um total de 57 crianças e adolescentes saudáveis, caucasianos e não-atletas. Dos 28 meninos, 11 eram pré-púberes (PP), sete púberes (PU) e 10 pós-púberes (PO). Das 29 meninas, 10 eram PP, nove PU e 10 PO. Foi utilizado um dinamómetro computadorizado (Cybex Norm) para medir a força isométrica de flexão do cotovelo (FC) nos ângulos de 60 e 90° e de extensão do joelho (EJ) em 45 e 60°. A força isocinética foi medida nos mesmos exercícios nas velocidades de 60 e 90° s Utilizou-se a análise de variância (ANOVA), usando dois fatores (gênero e maturação) para comparações, considerando-se p &lt; 0,05 o nível de significância e o teste de Tuckey para identificar as diferenças. A força de FC foi influenciada (p &lt; 0,05) pelo gênero e pelo grau maturacional nos testes isométricos, sendo que as diferenças entre gêneros ocorreram a partir da puberdade. Nesses testes, a força dos meninos PU foi cerca de 30% maior do que a das meninas PU e chegou a ser 77% maior do que a força dos meninos PP. A força de EJ foi influenciada (p &lt; 0,05) pelo gênero e pelo grau maturacional nos testes isocinéticos, em que os meninos PU foram em média 27% mais fortes do que as meninas PU e 97% (em 1 90 s- ) maiores do que os PP. Ao dividir a força pela estatura, os meninos continuaram sendo mais fortes (p &lt; 0,05) do que as meninas dentro do mesmo grau maturacional, com exceção dos testes isométricos de FC. Logo, essa descrição pode fornecer valores da força muscular de FC e EJ através de um procedimento metodológico, de acordo com o gênero e o grau maturacional. Apesar de os meninos serem sempre mais fortes do que as meninas e, em alguns exercícios, os grupos mais maduros mais fortes, não houve interação entre os fatores gênero e maturação nos testes isocinéticos de FC e isométricos de EJ e, por isso, as diferenças entre grupos maturacionais não estão apontadas

Fibromyalgie et performances musculaires

Objectives. The aim of the study was to compare various performances between women with fibromyalgia (FM) and healthy female controls. Methods. Subjects were sixteen women with FM and 85 healthy female controls. Patients and controls underwent examination of isokinetic muscle strength of dominant limb on a Cybex Norm dynamometer at 60 °/s and 180 °/s angular velocities. Fatigue resistance was isokinetically determined by thirty maximal concentric actions of knee flexors and extensors at 180 °/s angular velocity. Both sides were concerned, with a rest period of five minutes. Static trials were used to evaluated endurance. Results. Muscle strength, fatigue resistance and endurance were found to be, respectively, 39% ( p<0.001), 40% ( p<0.0001) and 81% ( p<0.0001) lower in the patient group. The pain score severity was higher in the FM group. Conclusion. This study confirms significant lower muscle performances in patients with FM. Our results strongly suggest a predominance of aerobic metabolism perturbation.

RECOVERY OF THE KNEES MUSCULAR STRENGTH AFTER ARTHROSCOPIC MENISCECTOMY

Sporting activities are responsible for the largest incidence of lesions in the knees, of which the lesions of ligaments and meniscus/cartilage are the most common. The object of this study was to verify the effectiveness of isokinetic dynamometry in the recovery of knees extensors and flexors muscular strength, after an arthroscopic meniscectomy. One month after meniscetomy of both knees, the patient with 58 years old, body weigt 85.3 kg and height 177.5 cm, came as a volunteer to realize the evaluation and recovery of the muscular strength of the lesioned knees, in Cybex Norm isokinetic dynamometry. The pretest consisted of five flexions and extension concentric repetitions of the knees at the speed of 60.s-1. The recovery consisted of a protocol of three series of five flexions and extension concentric repetitions of the knees at the speeds of 180.s-1, 120.s-1 and 60.s-1, in that order, two times a week, for eight weeks. The interval between the speeds was thirty seconds. The posttest was identical to the pretest. The results obtained (N.m) are in Table below. After eight weeks of recovery, the patient normalized the right and left knees flexors/extensors strength ratio from 66.4% and 83.9% to 67.9% and 69.7%, respectively and recovered the strength deficit presented in the initial evaluation. During the recovery, the patient didn't present pain and swelling. From the results presented by the case studied, it can be concluded that isokinetic equipment is effective in the recovery of extensor muscular strength and flexors of the knees, after meniscus/cartilage surgery.Table