We compared the electrical activities recorded from the muscles of the unexercised leg with changing the position of the contralateral stabilization bar to determine whether the degree of muscle contraction was influenced by the position of the bar during one-legged isokinetic exercise using an isokinetic dynamometer. The root mean square (RMS) values recorded from the medial hamstring sites of the unexercised legs showed a significantly higher value when the bar was located behind and on both in front of and behind the unexercised leg during one-legged extension exercise. Results from the isokinetic knee flexion exercise test indicated that a significantly greater RMS value was recorded from the vastus lateralis sites when the bar was located in front of and on both sides of the unexercised leg. During one-legged isokinetic extension-flexion exercise, the mean values of RMS voltage were greater when the bar was positioned in front of and on both sides of the unexercised leg in the vastus lateralis site. At the medial hamstring site, a greater value was noticed when the bar was located behind or on both sides.