Clinical significance of isokinetic muscles testing in evaluating and diagnosing sarcopenia in the elderly

Objective To investigate the correlations of indexes of isokinetic muscle testing with grip, the circumference of muscle, the time up and go test(TUGT), and the distance of 6-minutes walk test(6MWT). And to identify the availability of isokinetic muscle testing in diagnosing sarcopenia in the elderly. Methods A total of 27 elderly patients with sarcopenia admitted in rehabilitation department of our hospital from Jan.2017 to Dec.2017 were enrolled in this cross-sectional study.Patients were evaluated in many aspects, including comprehensive evaluation by the comprehensive assessment, the skeletal muscle mass detection by dual energy X-Ray absorptiometry, the power of gripping by dynamometer, the circumference of muscle of upper and lower extremities, the muscle strength by isokinetic muscle testing, the sports ability by TUGT and 6MWT. Results Isokinetic muscle testing including the knee flexion, knee extension, elbow extension, wrist extension, TUGT, 6MWT, the power of left gripping, the circumference of left forearm muscle showed a negative correlations to the age(r=-0.54, -0.44, -0.52, -0.61, -0.53, -0.41 and-0.39, P<0.05). A positive correlation were observed between TUGT and the age(r=0.44, P<0.05). The positive correlations between every index in isokinetic muscles testing and the power of both left and right gripping were observed(r=0.66, 0.67, 0.67, 0.67, 0.56, 0.62, 0.54, 0.54, 0.64, 0.59, 0.59 and 0.56, P<0.05). The knee flexion, knee extension, elbow flexion, elbow extension and wrist extension of Isokinetic muscle testing showed a positive correlations to 6MWT(r=0.71, 0.65, 0.62, 0.60 and 0.59, P<0.05). The knee flexion, knee extension, elbow extension and wrist extension of isokinetic muscle testing showed a negative correlations to TUGT(r=-0.57, -0.52, -0.42 and-0.48, P<0.05). Every index of isokinetic muscle testing showed a positive correlations to the circumference of both forearms(r=0.45, 0.47, 0.52, 0.42, 0.41, 0.44, 0.49, 0.52、0.60, 0.54, 0.44 and 049, P<0.05). Conclusions Isokinetic muscle testing can accurately evaluate the changes of muscle strength in the elderly with sarcopenia.It can be considered as the reference index of motor function in diagnosing sarcopenia in the elderly. Key words: Sarcopenia; Muscle strength