Physiologic responses of SCI subjects to electrically induced leg cycle ergometry

The purpose of this study was to determine steady-state physiologic responses of spinal-cord-injured (SCI) subjects to electrically induced leg-cycle ergometry, and to compare these responses to those of able-bodied (AB) individuals performing voluntary leg-cycle ergometry at the same power output (PO) levels. Twelve SCI subjects and 6 AB subjects exercised on a microprocessor-controlled functional neuromuscular stimulation (FNS) cycle ergometer. FNS of paralyzed leg muscles was delivered via skin-surface electrodes over the quadriceps, hamstring, and gluteal muscle groups. Subjects performed several 5-min bouts of progressive intensity cycling (6- or 12-W increments) at 50 r.p.m. Each bout was followed by a 5-min rest period. Oxygen uptake, pulmonary ventilation, and heart rate were significantly higher for the SCI group at each PO level. The data suggest that this FNS exercise may elicit metabolic and cardiopulmonary responses from FNS-trained SCI individuals that are of similar magnitudes to those elicited from AB individuals during jogging exercise. The authors therefore hypothesize that this mode of FNS exercise training may promote higher levels of aerobic fitness in many SCI individuals than can be obtained by conventional arm exercise (e.g. wheelchair propulsion, cranking).< >