Gain of muscle torque at low and high speed after isokinetic knee strengthening program in healthy young and older adults

Low-speed isokinetic exercise has been recommended to exert a maximal contraction and produce greater muscle torque than high-speed exercise in young adults. The purpose of this study was to compare the effectiveness of low- and high-speed isokinetic exercise programs for increasing muscle torque in young and elderly people. Twenty healthy elderly and 20 young subjects participated. The elderly subjects were divided into two groups. One group performed high-speed, (800°/s) isokinetic exercise training three times a week for the dominant-side knee extensor and low-speed (60°/s) exercise for the non-dominant side for 6 weeks. The other group was trained using the reverse exercise regime. The training program for the young subjects was the same as that for elderly groups. All subjects bad their knee extensor torque evaluated with an isokinetic test before and at 2-week intervals during the training program. For young and elderly groups, both high- and low-speed isokinetic exercise training increased extensor torque in low- and high- speed tests. For the young group, low-speed exercise effectively improved muscle torque at low and high-speeds. The improvement in slow muscle torque was significantly greater than that in fast muscle torque. For the elderly subjects, high-speed isokinetic exercise produced the greatest muscle torque at high speed in the first 2 weeks of training and demonstrated a sharp increase in muscle torque in the final 2 weeks. Low speed exercise frequently caused knee stress and the inability of some elder subjects to continue the exercises with maximal efforts. Our findings indicate that high-speed exercise may be more appropriate for the elderly, and low-speed exercise may be more appropriate for younger people.