Isokinetics and Exercise Science - Volume 1, issue 4
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Isokinetics and Exercise Science (IES) is an international journal devoted to the study of theoretical and applied aspects of human muscle performance. Since isokinetic dynamometry constitutes the major tool in this area, the journal takes a particular interest in exploring the considerable potential of this technology.
Isokinetics and Exercise Science publishes studies associated with the methodology of muscle performance especially with respect to the issues of reproducibility and validity of testing, description of normal and pathological mechanical parameters which are derivable from muscle testing, applications in basic research topics such as motor learning paradigms and electromyography. The journal also publishes studies on applications in clinical settings and technical aspects of the various measurement systems employed in human muscle performance research.
Isokinetics and Exercise Science welcomes submissions in the form of research papers, reviews, case studies and technical reports from professionals in the fields of sports medicine, orthopaedic and neurological rehabilitation and exercise physiology.
Abstract: A clinical study was conducted to determine if measurements of anterior knee laxity taken prior to Cybex testing differ from measurements obtained after testing. Twenty-eight patients who each had one anterior cruciate ligament (ACL)-injured knee and one normal knee participated in the study. Physical therapists-certified athletic trainers performed tests of anterior laxity on all knees using the KT-1000 knee ligament arthrometer. Patients were then tested on the Cybex at 60 and 240 deg/sec. Laxity measurements were repeated after Cybex testing. Data were analyzed by paired t-tests. Nonreconstructed ACL-injured knees showed significant laxity increases after Cybex testing for passive anterior drawer…with 15 lbs of force (t = 3.218, p < .01), with 20 lbs of force (t = 2.189, p < .05), and for quadriceps active displacement (t = 2.390, p < .05). Although not statistically significant, laxity decreases were observed for reconstructed ACL-injured knees for quadriceps active displacement. The laxity of normal knees did not change significantly for any tests. The authors recommended that clinicians consistently perform KT-1000 measurements either before or after more vigorous clinical evaluations of patients with ACL injuries. The laxity increases observed among nonreconstructed ACL-injured knees may encourage therapists and athletic trainers to consider controlling anterior tibial displacement in ACL-injured patients.
Abstract: The purpose of this study was to investigate the effect of hip position on the peak torques produced during isokinetic flexion and extension of the knee. Twenty-three normal subjects participated in the study. Using the Cybex II Dual Channel Dynamometer. the peak torques of knee flexion and extension of the dominant lower limb were evaluated with the hip fixed at 5. 80. and 110 deg of flexion. Varying hip position did not significantly affect the peak torques of knee extension. However. the peak torque of knee flexion produced at 5 deg of hip flexion was dramatically (25%) less than that…possible at 80 or 110 deg (torque at 80 deg > 110 deg > 5 deg). Consideration of the anatomy of the knee flexors and extensors demonstrated that the isokinetic torque curves conform to standard interpretations of length-tension relationships. It was concluded that (1) quadriceps femoris acts as a uniarticular muscle inasmuch as the peak torque of the isolated rectus femoris is minimally affected by hip position; (2) the peak torque of the biarticular hamstrings varies significantly with hip position; (3) the contribution of body weight should be considered when comparing peak muscle torques; and (4) length-tension relations must be considered in selecting test. exercise, and rehabilitative parameters for the knee.
Keywords: Length-tension relationships, hip position, biarticular muscles
Abstract: The purpose of this study was to determine the accuracy of predicting isokinetic knee extension and flexion peak torques from anthropometric dimensions. Male college athletes (N = 105) were evaluated for concentric isokinetic knee extension and flexion torques at 60, 120, 300, and 450 deg/sec using a Biodex dynamometer. Anthropometric dimensions included height, body mass, lean body mass (LBM), percent fat, age, and other various measured and derived leg indices. Multiple regression analysis on a validity sample (n = 80) selected midthigh cross-sectional area (CSA), height, and LBM to predict knee extension torques at 60, 120, 300, and 450 deg/sec…(R = .70–.80); at 300 deg/sec, body mass replaced LBM in the prediction equation (R = .79). Muscle (SA was the only variable common to all prediction equations to estimate knee flexion torque at all speeds, although the multiple correlations remained comparable (R = .55–.80). The prediction equations were cross-validated on a sample of 25 randomly selected subjects from the original group and produced correlation coefficients of r = .51–.76 for estimating concentric isokinetic knee torques. It was concluded that anthropometric dimensions can be used to estimate isokinetic leg strength levels in male collegiate athletes and provide additional information for the preparticipation physical screening. These findings may be useful in the prevention of athletic injuries to the lower extremities.
Abstract: This study was devised to assess the different effects of concentric and eccentric actions on the tibialis anterior in a short-term strengthening regimen. It was hypothesized that any changes that may emerge in a pre- and posttest strength assessment would be from primarily neurologic alterations. Forty-four subjects were randomly divided into a control (n = 15), eccentric training (n = 14), and concentric training (n = 15) groups. The training groups performed eight training sessions over a 3-week period, allowing at least 1 day of rest between sessions. The training employed a modified daily adjusted progressive resistive exercise technique that…used Thera-Band (Hygenic Corp., Akron, OH) as the resistance mode. Pre- and posttest data were collected via a Biodex dynamometer (Shirley, NY) of the ankle dorsiflexion pattern (30 and 90 deg/sec). No significant changes were observed in peak torque, and only the eccentrically trained group exhibited significant change of the total work performed of an eccentric pattern at 30 deg/sec. No significant changes were seen at 90 deg/sec. The results show a significant increase in total work at 30 deg/sec without an increase in peak torque. An alteration of the shape of the generated curve was seen with a “smoothing” occurring during the posttest. This finding is supportive of an enhancement of neuromuscular integration and an enhancement of neural function in the recruitment of muscle fibers during eccentric activation.
Abstract: The purpose of this study was to compare glenohumeral internal and external rotation concentric and eccentric peak torque values when assessed from both the frontal and scapular planes. Twenty-one men (mean age = 21.4 years, mean height = 180.47 cm, mean weight = 80.8 kg) had their nondominant shoulder isokinetically tested for shoulder concentric and eccentric internal and external rotator strength at 60 deg/sec. Subjects were tested in both the frontal and scapular planes in randomly assigned order during one test session. Eleven subjects returned 1 week later for an identical retest session to establish the reliability of the procedure…(r = .76–.94). No differences were found in concentric and eccentric peak torque values between planes for either shoulder internal or external rotation (p > .05). Analysis of variance indicated that eccentric values were greater than concentric values and internal rotation values were greater than external rotation values in both planes. Because there may be some anatomical advantage to testing in the scapular plane, clinicians should consider placing patients in the scapular plane when testing shoulder rotator peak torque.
Abstract: This study investigated intratester, intertester, and intrasubject reliability, within and between two test sessions, of reciprocal contractions of the quadriceps and hamstrings at 90°/sec and 200°/sec in healthy individuals. The MERAC (Muscular Evaluation Rehabilitation and Conditioning, Universal Corporation, Cedar Rapids, IA) was used to test the dominant lower extremity of 33 healthy subjects who attended two test sessions scheduled two weeks apart. For each observation, the subject performed four submaximal and three maximal warm-up reciprocal contractions prior to three maximal test contractions of reciprocal, knee flexion, and extension at each speed. Three observations occurred per test session, one by one…examiner and two by a second examiner. The order of examiners and speeds was random. The variables of peak torque, average work, and average power were measured. All correlation coefficients for intratester and intertester reliability were statistically significant (p < 0.05). Further research is indicated to determine isokinetic testing protocols that optimize stability of performance.
Abstract: The purpose of this investigation is (1) to determine if a Feldenkrais awareness through movement technique creates a measurable physiological change in muscular activity, (2) to determine if there is a perceptual recognition of a physiological change, and (3) to determine if perceptual recognition may be induced as a result of suggestion, imagery, and visualization. Twenty-one subjects were divided into two groups. Electromyographic (EMG) activity was recorded during a flexion movement with surface electrodes placed over the left lumbar paraspinal muscles at L3 -L5 and over the right external oblique muscle. Ratings of perceived exertion (RPE) were taken after…the EMG testing. Correlated t tests were performed to test significant differences within each group, and small sample means tests were performed to test for significant differences between the two groups. The results show that there was a significant difference in EMG activity of the flexors and of RPE values within each group; however, there were no significant differences between the two groups. The results support the following conclusions: (1) the Feldenkrais method produces a change in the amount of muscular activity as measured by EMG required to perform a movement task; (2) a perceptual recognition of the change in muscular activity is produced; and (3) this perceptual recognition of change is not the direct result of the use of suggestion, imagery, and visualization. This study supports the use of the Feldenkrais Method clinically for increasing attention to posturing, movements, and changes in muscular activity with movements.