Muscle Stimulation Waveform Timing Patterns to Increase Muscular Endurance in Functional Electrical Stimulation Pedaling Using a Forward Dynamic Model

Functional electrical stimulation (FES) pedaling can provide spinal cord injured (SCI) individuals with cardiorespiratory and muscular strength benefits. A limiting factor in FES pedaling benefit to the SCI population is the low endurance of electrically stimulated muscle. Because a reduction of the force-time integral for a single muscle group leads to an increase in the duration of the force generating capacity of the muscle group [1–2], we sought to test whether reducing the stress-time integral of multiple muscle groups working together could increase the endurance and work performed during FES pedaling. To this end, the objectives of this study were to: 1) compute the electrical stimulation timing patterns that minimize the stress-time integral of the muscles used to pedal a FES ergometer, 2) compare the simulated mechanical energies generated by the muscles with the computed electrical stimulation on and off times, and 3) test the efficacy of the computed electrical stimulation timing patterns in an experimental setting.