Isokinetics and Exercise Science - Volume 9, issue 1

Authors: Bygott, I.-L. | McMeeken, J. | Carroll, S. | Story, I.

Article Type: Research Article

Abstract: The reliability of several gravity correction procedures was examined using a KinCom trunk dynamometer in thirty subjects with no history of low back pain. The procedures, including the KinCom software procedure, an isometric mode and a passive force curve mode were evaluated for variability. Mean differences and standard deviation of difference scores were used to indicate systematic and random variability as well as coefficient of variation of method error to express variability relative to score magnitude. …Overall, the isometric and eccentric passive force curve modes were most reliable while the KinCom software method showed greatest variability. In all modes, considerable variability was present between the angles of 5 to 15 degrees for flexion and between 5 to 20 degrees for extension. These findings indicate that alternative methods of gravity correction which may be more reliable than those provided by the supplier, should be used to ensure greater reproducibility of results. Show more

DOI: 10.3233/IES-2001-0056

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 1-9, 2001

Authors: Ebersole, Kyle T. | Housh, Terry J. | Johnson, Glen O. | Evetovich, Tammy K. | Smith, Douglas B.

Article Type: Research Article

Abstract: The purpose of this investigation was to examine the mechanomyographic (MMG) responses to maximal concentric (CON) and passive leg extension movements. Eight adult females performed maximal CON muscle actions and passive leg extension movements of the dominant leg on a calibrated CYBEX 6000 dynamometer at velocities of 30, 90, and 150^{\circ}\cdot s^{-1} . MMG and electromyographic (EMG) signals were simultaneously recorded from the vastus lateralis (VL). The results indicated velocity-related …dissociations among MMG amplitude, EMG amplitude, and peak torque during the maximal CON muscle actions. For the passive leg extension movements, however, the EMG amplitude values at each velocity were not significantly (p > 0.05 ) different from the values at rest, but the MMG amplitude increased significantly (p < 0.05 ) with velocity. It was hypothesized that the velocity-related increase in MMG amplitude for the passive leg extension movements was independent of VL activation and may have been associated with turbulences of the intracellular and extracellular fluid mediums and/or cross-talk from the hamstring muscles. Show more

Keywords: mechanomyography, electromyography, passive movements

DOI: 10.3233/IES-2001-0058

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 11-18, 2001

Authors: Mayer, F. | Horstmann, T. | Bäurle, W. | Grau, S. | Handel, M. | Dickhuth, H.H.

Article Type: Research Article

Abstract: The correction of ``muscular imbalances'' is assumed to be important in therapy of shoulder pathologies and muscular strengthening. However, it is not clear how these imbalances should be defined and the extent to which conclusions can be drawn, relevant to therapy and training. Statements on physiological strength ratios and deviations from these are only possible using a valid and reliable measurement. Isokinetic shoulder strength measurements can be considered validly isokinetic up to 180 ^{\circ} …/s. Differentiation between the various types of work and movements is reliable within a test-retest variability of 15--20%. The maximum torque serves as a reliable parameter and additional information is obtained by determination of local muscle fatigue. In this context, important considerations are the test method and especially positioning and fixation. However, the direct application of isokinetically determined strength values in training and rehabilitation is only possible when the exercise position agrees with the position during measurement. This is usually not the case. Since isokinetic movements are rarely if ever encountered in everyday living or sports, data obtained by these methods can hardly be used for training management and should mainly be used as a therapy control. Adequately reliable data on the strength ratio of shoulder movements can be obtained within narrow limits by isokinetic strength measurements. However, in spite of critical assessment of the methods, it is recommended that isokinetic measurements should be uniformly performed in accordance with the queries in order to guarantee comparability and interpretation. In addition stress in everyday living and sports lead to specific changes which should always be interpreted on the basis of method-specific criteria and exercise-specific movements. Taking functional-anatomical and methodical considerations into account, isokinetic measurements deliver valuable information for training and therapy within the framework of medically and scientifically founded strength diagnostics. Show more

Keywords: isokinetics, shoulder, rehabilitation, review

DOI: 10.3233/IES-2001-0059

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 19-25, 2001

Authors: Binder, Dana | Brown-Cross, Dawn | Shamus, Eric | Davies, George

Article Type: Research Article

Abstract: The objective of this study was to examine possible differences in peak torque, total work and power between the quadriceps muscles relating to smaller or larger Q-angle. Twenty asymptomatic females between the ages of 23 to 27 met the inclusion criteria. Each subject answered a questionnaire, had their Q-angles measured, and performed concentric knee extension testing on the Biodex at speeds 60, 180 and 300^{\circ} /sec. T-tests were used and significance was set at p< …0.05 . The results showed the quadriceps with the smaller Q-angle had a significantly greater: peak torque at 300^{\circ} /sec and at the combined peak torque speeds, total work at 300^{\circ} /sec and power at 60^{\circ} /sec and at the combined power speeds as well as trends in other tests. Understanding Q-angle difference may provide scientific and clinical rationale for the design of rehabilitation programs for patients with patellofemoral or anterior knee pain syndromes. Show more

DOI: 10.3233/IES-2001-0060

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 27-30, 2001

Authors: Kellis, Spiros | Gerodimos, Vasilios | Kellis, Eleftherios | Manou, Vasiliki

Article Type: Research Article

Abstract: Isokinetic dynamometers are extensively used to monitor strength development in young soccer players. The purpose of this study was to examine the effects of age, velocity and leg of preference on the peak moments in young soccer players. One hundred and fifty eight soccer players (age = 13.2 \pm 2.1 years; height = 1.6 \pm 1.4 ; body mass = 51.6 \pm 14.89 kg) performed maximum knee extension and flexion …efforts at 30^{\circ} /s, 90^{\circ} /s, 120^{\circ} /s and 180^{\circ} /s of both legs and under eccentric and concentric conditions. The absolute (Nm) and the relative (Nm/Kg) peak moment of forces were further analyzed. Four-way analysis of variance designs were applied to examine the effects of age, angular velocity, leg of preference and muscle action (eccentric -- concentric) on the recorded moments for knee extension and flexion. The isokinetic moment of force of knee extensors ranged from 1.01 \pm 0.19 to 3.58 \pm 0.50 Nm/kg. The knee flexion moments ranged from 0.95 \pm 0.16 ~Nm/kg to 2.42 \pm 0.59 Nm/kg. For all testing conditions eccentric moments were greater than the corresponding concentric (p<0.05 ). The isokinetic moment under all testing conditions increased significantly (p<0.05 ) as chronological age increased from 10 to 18 years. Furthermore, the isokinetic moment of the preferred leg, collapsed for the effects of age, angular velocity and muscle action, was significantly greater compared to the moments of the other leg. The strength profiles developed in the present study can assist in the establishment of baseline data in young soccer players. Show more

Keywords: strength, knee, isokinetics, soccer, children

DOI: 10.3233/IES-2001-0061

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 31-39, 2001

Authors: Heitkamp, H.-C. | Horstmann, T. | Mayer, F. | Weller, J. | Dickhuth, H.-H.

Article Type: Research Article

Abstract: Men and women differ in strength according to the muscle mass of knee extensors and flexors. Side differences between left and right are frequently reported. We measured isokinetic strength and balance performance in 7 men and 8 women and calculated side differences before and after 6 weeks of balance training conducted twice a week for 25 min. Before training, extension and flexion strengths were 70% training gain was 12% in men and 11% flexors were reduced …to 1.0 and 0.8% respectively. All participants improved balance performance in one leg standing time. Men and women with comparable anthropometric data and level of physical activity improved strength by balance training without strength training. This study also underscores importance of balance training as a preventive measure especially in old age. Show more

Keywords: balance training, knee flexors, knee extensors, side difference

DOI: 10.3233/IES-2001-0062

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 41-44, 2001

Authors: Ayalon, M. | Rubinstein, M. | Barak, Y. | Dunsky, A. | Ben-Sira, D.

Article Type: Research Article

Abstract: The purpose of this study is to assess the ability of clinicians to identify false isokinetic strength test of the knee flexors and extensors, based only on the shape of the torque curve. The concentric strength was measured bilaterally using an isokinetic dynamometer at 60^{\circ} /sec. Each subject performed two modes of testing: a) A Genuine strength test (GST) which consisted of five consecutive cycles of knee extension and flexion at maximal effort. b) A …false strength test (FST) which consisted of five consecutive cycles of knee extensions and flexion attempting to feign pain. For each test, the torque curves were printed and presented to four judges to mark each of the tests as a GST or a FST based on the shape of the torque curves. The mean percentage of success in identifying a GST and a FST for the 4 judges was 91.9% (range = 82.5--95%) constraints, which were imposed on the judges, the rate of correct classification was high. Show more

Keywords: isokinetic, torque curve, feigned strength test

DOI: 10.3233/IES-2001-0063

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 45-50, 2001

Authors: Dvir, Zeevi

Article Type: Article Commentary

Abstract: The excellent paper by Ayalon et al. joins a growing line of studies that have looked into using isokinetic dynamometry for identifying submaximal muscular performance (feigned weakness). Invariably the protocols applied in these studies have used maximal performance as the baseline to which its submaximal counterpartwas compared. Furthermore, measurement of maximal performance preceded submaximal performance. Inasmuch as the ‘maximal performance’ component is concerned, the measurements in all studies were based on previously reported protocols which …evolved to become standard. The same protocols were used for measuring the feigned weakness, the only variation being the instructions administered. It is this element that is the focus of this commentary. Show more

DOI: 10.3233/IES-2001-0064

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 51-51, 2001

Authors: Bygott, I.-L. | McMeeken, J. | Carroll, S. | Story, I.

Article Type: Research Article

Abstract: The validity of gravity correction procedures was examined using a KinCom trunk testing dynamometer. Gravity correction measures were expressed as a percentage of the anthropometric estimate of head, arms and trunk weight at 25^{\circ} of trunk flexion and extension. Polynomial regression was used to describe gravity correction scores across range and compared to cosine curves generated by the supplier's gravity correction software (GCS) at 25^{\circ} . The GCS method least reflected …the percentage body weight estimate although none of the gravity correction methods closely matched the anthropometric estimate. Eccentric passive force curves and isometric curves were highest in both trunk flexion and trunk extension directions. Trunk extension curves for all gravity correction modes were consistently lower than trunk flexion curves and scores were higher for both directions between 5 and 20^{\circ} . Cosine curves were different from real curves for all modes. Attenuation of forces may have occurred in the spinal structures for both extension and flexion. These preliminary results suggest caution in the use of gravity correction in trunk testing. Methods which represent all passive forces acting on the force pad throughout range of motion should be employed to validate actions being tested. Show more

DOI: 10.3233/IES-2001-0067

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 53-64, 2001

Authors: Mandalidis, D.G. | Donne, B. | O'Regan, M. | O'Brien, M.

Article Type: Research Article

Abstract: This study has investigated the reliability of an isokinetic testing protocol for the shoulder rotators in the scapular plane to estimate the minimum variation of rotator moment needed to detect a significant change between two tests. Concentric and eccentric actions of shoulder internal and external rotation were assessed in a group of 31 male students. Measurements were performed on the dominant and non-dominant sides, at 60 and 120^{\circ} \cdot …s^{-1} , using an isokinetic dynamometer. Each volunteer was assessed in the seated position, with the arm at 45^{\circ} of abduction and 30^{\circ} of horizontal adduction. The intraclass correlation coefficient (ICC 3,1), the standard error of measurement (SEM) and the limits of agreement (LOA) were used to determine inter-session reliability and the magnitude of the measurement error for gravity corrected peak and average moment. Moderate to high ICC values (0.76--0.93) were observed for all measured variables. The measurement error associated with repeated measures ranged between 3.9--13.3 Nm. Both SEM and LOA revealed greater measurement errors for peak compared to average moment, eccentric compared to concentric actions, and internal compared to external rotation. The findings of the present study suggested that decline or improvement in isokinetic shoulder rotator moment should only be considered as a significant response to a pathology or an intervention, when the moment data obtained in consecutive repeated measures is lower or greater than the measurement error. Show more

Keywords: reliability, isokinetic, shoulder rotators, scapular plane

DOI: 10.3233/IES-2001-0066

Citation: Isokinetics and Exercise Science, vol. 9, no. 1, pp. 65-72, 2001