Abstract
The bilateral deficit (BD) during force production may result from decreased activation of either slow-twitch or fast-twitch muscle fibers. The purpose of this study was to investigate the effect of velocity on the BD and estimate the relative contribution of muscle fiber type to the BD in untrained women. Twelve subjects performed three concentric reciprocal knee extension and flexion repetitions at isokinetic speeds of 60, 120, 180, 240 and 360 deg/sec using both unilateral limbs and bilateral limbs. Results showed that the extension peak torque BD decreased significantly (p < 0.05) at speeds of 60 to > 120 deg/sec, whereas the flexion peak torque BD decreased significantly at speeds of 60 to > 180 deg/sec. These results appear to demonstrate that decreased activation of primarily slow-twitch muscle fibers may be responsible for the BD during dynamic knee extension and flexion exercise in women.