Within-cycle characteristics of the wheelchair push in sprinting on a wheelchair ergometer

To investigate power output and torque production in wheelchair sprinting, six able-bodied subjects performed nine 20-s sprint tests on a stationary wheelchair ergometer (load 0-8 kg). Ergometer data were analyzed and combined with kinematic data and surface electromyography. Of all power and torque parameters investigated, only maximal power output was independent of load (mean peak value 375 W, one-sided). Mean power output is suggested to be a useful indicator for anaerobic power production, but test conditions concerned speed in relation to handrim diameter should be specified. The relevance of the "mechanical constraint principle" for handrim propulsion is discussed. Within one cycle, power and torque curves showed a negative deflection at the beginning and a valley approximately halfway through the push phase. The relation of these phenomena to kinematic parameters and muscle activity is discussed.