Predicting the Effect of Pulse Duration on Fatigue during Electrically Stimulated Non-isometric Contractions

Functional electrical stimulation (FES) is increasingly used by individuals with paralysis to regain functional movement, but muscle fatigue can limit the applicability of this technology. Mathematical predictions of power loss during electrically stimulated muscle contractions are essential when trying to not only minimize fatigue, but also determine the relative contributions of force and velocity to fatigue. Our previous mathematical model of non-isometric muscle fatigue for electrical stimulation induced, seated leg extensions accounted for the effect of applied load, but not the effect of pulse duration [1]. Therefore, our objectives were: 1) model muscle fatigue at different pulse durations and 2) experimentally validate the model with new subjects and thus predict the effect of pulse duration on fatigue.