Isokinetics and Exercise Science - Volume 8, issue 3

Authors: Schmitz, Randy J. | Arnold, Brent L. | Perrin, David H. | Granata, Kevin P. | Gaesser, Glenn A. | Gansneder, Bruce M.

Article Type: Research Article

Abstract: {\it Purpose:} The purpose of this study was to determine if surface electromyography (EMG) could be used to index fatigue during isotonic and maximal voluntary isometric contractions (MVIC) of the knee extensors in men and women. {\it Methods:} Ten males (age = 22.1 \pm 3.3 yr, ht = 180.3 \pm 5.5 cm, mass 78.7 \pm 5.1 kg) and ten females (age = 23.9 \pm 4.6 yr, ht = 163.7.3 \pm 11.1 cm, mass 63.2 \pm 7.4 kg) underwent …one isometric (120 s MVIC of the knee extensors) and one isotonic (120 maximal effort isotonic contractions at a resistance of 25% of the MVIC peak torque determined on the testing day) exercise session separated by at least 48~hrs. The EMG signal was collected from the vastus lateralis during both exercise protocols using standard EMG collection techniques. Average torque (AT) was calculated from each 3 s window of the 120 s MVIC, and the average peak power (APP) was calculated for every 3 consecutive contractions during the dynamic exercise. {\it Results:} Both the isometric and isotonic fatigue protocols resulted in significant (p<0.05) decreases in AT and APP, respectively. During the isotonic exercise protocol, decreases in APP during contractions 31--54 were significantly greater (p<0.05) for males than females. Time-amplitude domain processing of the EMG data demonstrated significant decreases in the root mean square amplitude during the course of isometric exercise (p<0.05) but not during isotonic exercise (p>0.05). A main effect for gender (p<0.05) revealed larger EMG amplitude for females when compared to males during isotonic exercise. {\it Conclusions:} These results indicate that gender may be a factor in the development of dynamic fatigue and that EMG can index fatigue during a sustained MVIC. Show more

Keywords: fatigue, muscle assessment, EMG, power

DOI: 10.3233/IES-2000-0042

Citation: Isokinetics and Exercise Science, vol. 8, no. 3, pp. 119-127, 2000

Authors: Shewokis, Patricia A. | Kennedy, Christopher Z. | Marsh, Jennifer L.

Article Type: Research Article

Abstract: The purpose of this study was to examine the influence of no-error knowledge of results (KR) and relative frequency of feedback on the performance and retention of an isokinetic, internal shoulder rotation exercise. Males (N =32 ), who were free of any shoulder injuries, uninvolved in organized athletics, and unfamiliar with isokinetic testing; performed 90 acquisition trials over a period of three days at 70% after the last acquisition session followed a 10-trial delayed retention …test. Participants received error KR in either a 10% bandwidth, yoked, verbal 100% KR condition. Retention results revealed that participants in the 10% bandwidth and yoked conditions performed more consistently than both of the 100% to be more accurate than their yoked counterparts. Our findings support previous research and provide empirical support for using reduced amounts of extrinsic feedback when learning a sub-maximal, isokinetic strength task. Show more

DOI: 10.3233/IES-2000-0043

Citation: Isokinetics and Exercise Science, vol. 8, no. 3, pp. 129-139, 2000

Authors: Horstmann, T. | Lukas, C. | Mayer, F. | Winter, E. | Ambacher, T. | Heitkamp, H.-C. | Dickhuth, H.-H.

Article Type: Research Article

Abstract: Achilles tendon repair with following immobilisation causes atrophy of the calf musculature. The aim of this study was the long term evaluation of the strength and strength endurance deficit ten years after the injury. 63 patients (48 male, 15 female) were tested 10.8 years after achilles tendon rupture repair and subsequent 6-week immobilisation. The test was made in the eccentric (60^{\circ} /s), isometric and concentric (60^{\circ} /s, 180^{\circ} /s) mode for …plantarflexion and dorsiflexion with a Lido Active dynamometer. The mean peak torque of the best 3 of 5 movements and the work over 1 minute (180^{\circ} /s) were evaluated for plantarflexion and dorsiflexion. The circumference of the calf musculature and the range of motion of the ankle (ROM) were measured. Differences to the non-operated side were assessed with the Wilcoxon matched pairs test and adjusted with the Bonferroni method. The mean peak torque in all modes showed no statistically significant difference between the operated and non-operated legs ten years after immobilisation. The work over 1 minute was markedly reduced for the operated leg in plantarflexion (516 J operated versus 634 J non-operated, p< 0.001 ). The circumference of the calf musculature (-1.1 cm) and the ROM (-3.5 ^{\circ} plantarflexion, -1.9 ^{\circ} dorsiflexion) were also reduced (p< 0.001 ). It seems that a selective atrophy of the slow twitch fibers is relevant for the durable loss of musculature and the weakened calf musculature in the strength endurance test. Early remobilization should be chosen after reconstruction of the achilles tendon, and more strength endurance training must be done at the end of the rehabilitation. Show more

Keywords: achilles tendon, muscle atrophy, strength, strength endurance, rehabilitation, slow twitch fibers

DOI: 10.3233/IES-2000-0044

Citation: Isokinetics and Exercise Science, vol. 8, no. 3, pp. 141-145, 2000

Authors: Phillips, Beverley A. | Lo, Sing K. | Mastaglia, Frank L.

Article Type: Research Article

Abstract: {\it Objective:} To obtain normal torque values for the knee extensors and flexors using a Kin-Com dynamometer in a large group of normal subjects. {\it Design:} We used a Kin-Com dynamometer to measure the isokinetic torque at 60 and 120 deg/sec and isometric torque of the knee extensors and flexors in a sample of 200 normal subjects aged 20 to 69 years. {\it Results:} Reliability coefficients for average and isometric torque were …>0.82 for both intra- and inter-session reliability. Male subjects exerted a significantly greater isokinetic and isometric torque than female subjects for both muscle groups and age was a significant predictor of torque for all tests. The 5th percentile values, as the lower limit of normal, are reported separately for gender and side of testing for each decade of age, and may be used for comparison to patient data providing that the specified testing protocol and a Kin-Com dynamometer are used. Show more

Keywords: normal, isokinetic, isometric

DOI: 10.3233/IES-2000-0045

Citation: Isokinetics and Exercise Science, vol. 8, no. 3, pp. 147-159, 2000

Authors: Mouraux, D. | Stallenberg, B. | Dugailly, P.-M. | Brassinne, E.

Article Type: Research Article

Abstract: This study was designed to investigate the effects of six weeks submaximal eccentric training on concentric and eccentric isokinetic peak torque and cross sectional area (CSA) (muscle and tendon) of calf muscle. Six men and four women volunteered as subjects for this study. Peak torque values for plantar flexion were determined at 30^{\circ} /s, 60^{\circ} /s and 90^{\circ} /s (concentric and eccentric) using a Cybex^{\textregistered} Norm before the training, …3 weeks after the beginning and at the end of the sixth week. Following training, peak torque increased in the concentric and eccentric modes in both the trained (p<0.001 ) and untrained (p<0.01 ) side. No significant change in CSA was noted. The results of this study indicate that after 6 weeks of submaximal eccentric training the strength gained was not completely specific to the contraction type used in training. Transfer of training took place. Neither muscle nor tendon hypertrophy was observed, suggesting the involvement of neural adaptation. Show more

DOI: 10.3233/IES-2000-0046

Citation: Isokinetics and Exercise Science, vol. 8, no. 3, pp. 161-167, 2000

Authors: David, Guy | Dvir, Zeevi | Simmons, Neil | Magarey, Mary | Jones, Mark | Turker, Kernal | Sharpe, Margaret

Article Type: Research Article

Abstract: Quantitative assessment of supraspinatus (SSp) strength can add substantially to the understanding of the underlying pathomechanics and recovery status of this critically important shoulder joint muscle. Since strength measurement of the SSP is an involved procedure which at times could be contraindicated, obtaining indirect but well correlated evidence in the form of muscle dimensional size may be an alternative method. The objective of this study was therefore to examine the relationship between SSp size and strength …in a group (n =16 ) of asymptomatic normal male adults. Strength during rotations, external (ER) and internal (IR), of the shoulder joint was measured using isokinetic dynamometry. The representative morphological dimension of the SSp was its width as calculated from ultrasonographic imaging of the longitudinal cross section. The main findings indicated a moderate to strong correlation with ER strength (r =0.65 to 0.85 ). In contrast, no parallel association was indicated with respect to IR. Similar patterns were found for the right and left shoulders. It is concluded that ultrasonography of the SSp can furnish valuable information about the strength of this muscle in asymptomatic subjects. However, clinical studies are essential for vindication of this technique with respect to symptomatic shoulders affected mainly with rotator cuff dysfunction. Show more

Keywords: strength, muscle, measurement, morphology

DOI: 10.3233/IES-2000-0047

Citation: Isokinetics and Exercise Science, vol. 8, no. 3, pp. 169-174, 2000

Authors: Croisier, Jean-Louis | Crielaard, Jean-Michel

Article Type: Research Article

Abstract: The purpose of this study was to determine the isokinetic profile of specialized athletes with previous hamstring tears and recurrent complaints upon return to sports activities, using a Kintrex 500 dynamometer. Twenty-three subjects were examined through a concentric protocol and fifteen of them benefited from a complementary eccentric assessment. Despite the fact that some cases presented normal isokinetic results, the statistical analysis has demonstrated particular features. In reference to the non-involved side …performances, the average reduction of peak torque (PT) of the injured muscles surpassed 20% relationship between bodyweight normalized PT and angular velocity demonstrated significant differences in comparison with those of selected non-injured sprinters, most notably in the eccentric sector. A mixed ratio (Flexors_{\rm eccentric} /Quadriceps_{\rm concentric} ) appeared significantly reduced (0.75 \pm 0.23 ) for the injured leg, in comparison with the contralateral non-injured limb (0.90 \pm 0.16 ) and with a control population (0.98 \pm 0.14 ). For the eccentric mode, the angle of peak torque (APT) of the strained muscle occurred in an abnormal articular sector corresponding to a weaker hamstring muscle lengthening than normal. These observations strongly suggest that, among the causative factors, the persistence of muscle strength abnormalities gives rise to recurring hamstring injuries. Show more

DOI: 10.3233/IES-2000-0048

Citation: Isokinetics and Exercise Science, vol. 8, no. 3, pp. 175-180, 2000