The effect of steering on the physiological energy cost of wheelchair propulsion.

Previous studies of the energy cost of wheelchair propulsion have used ergometers or tracks requiring little steering. We have measured minute ventilation (VE), oxygen consumption (VO2), carbon dioxide output (VCO2) and heart rate (HR) during exercise in a two arm, hand-rim propulsion wheelchair on a treadmill, and on three tracks of increasing tortuosity in eight able-bodied subjects. During propulsion at 0.6 m/sec, VE, VO2, and VCO2 were significantly greater on the track with the maximal steering component than on that with the minimal steering component, or on the treadmill with no steering component. Heart rate was significantly higher on the maximal compared to minimal steering component track. Exercise at speeds varying from 0.2 to 1.0 m/sec showed that VO2 and VCO2 were significantly higher on the medium steering component track than on the treadmill at speeds of 0.6 m/sec and above. We conclude that the effort of steering contributes significantly to the energy cost of wheelchair propulsion particularly at higher speeds.