Physiologic costs of computer-controlled walking in persons with paraplegia using a reciprocating-gait orthosis

Blood pressure, heart rate, oxygen uptake, cardiac output, and the surface electromyogram from key muscle groups in the upper body were measured in four subjects with paraplegia during ambulation using only a reciprocating-gait orthosis (RGO) and using an RGO with movement assisted by functional electrical stimulation (FES) of the hamstring and gluteus maximus muscles. These data were compared to data collected on four able-bodied control subjects during ambulation at matched speeds. Whether walking with FES and RGOs or walking with RGOs alone, subjects had an optimum gait speed at which efficiency was highest. For paralyzed subjects using FES, the optimum walking speed was approximately 1.5 mph (2.4km/hr); without FES, the optimum speed averaged about 0.75mph (1.2km/hr). Blood pressure, heart rate, oxygen uptake, and cardiac output were measured during ambulation with FES and were found to be higher than those of controls, but they were significantly lower than those in the paralyzed subjects in RGOs with no FES. Electromyogram studies showed that the activity in upper body muscles was much higher when walking in RGOs without FES than in RGOs with FES.