Evaluation of rapid force development using the maximum force produced by pulse height control

Abstract

The ability of rapid force development is one of the important factors for improving the physical performance. It has been known that rapid isometric force is controlled by a central motor program to keep the rise time relatively constant independent of force amplitude (pulse height control). The advantage of using pulse height control is to increase rate of force with force amplitude. However, this strategy is thought to be applicable up to about 50-60% of MVC. When the force level increases further, subjects often switch to pulse width control to increase the time to peak force. The purpose of this study was to determine the force level (turning point) at which subjects switch from pulse height control to pulse width control. This turning point was defined as the maximum force produced by pulse height control. We then attempted to examine whether this turning point is different among subjects. Our results showed that a turning point (%MVC) between two strategies was detected in all subjects and the mean values were significantly higher in the sprinter group than that in the control group. Our results suggest that each subject has different limits of force level produced by pulse height control.