PEDAL FORCES PRODUCED DURING NEUROMUSCULAR ELECTRICAL-STIMULATION CYCLING IN PARAPLEGICS

This study investigated forces applied to the pedal of a cycle ergomet er by paraplegic subjects undergoing neuromuscular electrical-stimulat ion-induced leg exercise. The patterns of force application were compa red with those of able-bodied subjects cycling under voluntary muscle control in order to investigate the effectiveness of the muscle stimul ation parameters. Results show that paraplegic subjects applied signif icantly larger peak forces than the able-bodied subjects because of th e short duration of neuromuscular stimulation. Able-bodied subjects we re able to achieve the same average workload by applying smaller force s over a greater percentage of each crank revolution. it is suggested that the large forces produced by paraplegic subjects contribute to th e low efficiency reported by previous studies, and that increasing the range of angles over which muscles are stimulated may provide a means to increase the efficiency of cycling for paraplegic individuals. Rel evance-Cycling using neuromuscular electrical stimulation has been pre scribed as an exercise regime for spinal-cord-injured individuals with proposed benefits such as augmented cardiovascular fitness, reversal of muscle wasting, increased blood flow in the legs, and reduced incid ence of muscle spasms. The intensity and duration of such exercise is limited due to rapid fatigue of the leg muscles and this reduces the p otential benefit to some patients. The purpose of the study was to imp rove our understanding of the mechanics of electrically-stimuated cycl ing and the loads exerted by paraplegic subjects during this activity.