Using pulse doublets to enhance muscle force for FES

A procedure has been developed to determine the optimal number of pulses and set of interpulse Intervals In an N-let (set of N closely spaced stimulation pulses) that will elicit the most efficient twitch response in human skeletal muscle. It was found that using a doublet (N = 2) produced the largest torque-time Integral per pulse. Since muscular fatigue during electrical stimulation appears to be a function of the number of pulses received, the doublet was Identified as the optimal twitch producing mechanism. Preliminary results indicate that using doublets Instead of the single pulses used for conventional pulse train stimulation leads to a significant Increase in the length of time an isometric contraction can be maintained. This new stimulation methodology has great potential for alleviating the problem of muscular fatigue during functional electrical stimulation.