POWER OUTPUT FOR WHEELCHAIR DRIVING ON A TREADMILL COMPARED WITH ARM CRANK ERGOMETRY

Objectives-The limiting factors with regard to power output available for wheelchair ambulation have not been identified. The aim of the pre sent study was to correlate power output during wheelchair driving wit h (i) power output and oxygen uptake during arm crank ergometry and (i i) arm muscle strength. Methods-Eleven disabled men were examined for maximal power output (POmax) during wheelchair driving on a treadmill and during arm crank ergometry. Oxygen uptake (Vo(2)) was recorded at submaximal and maximal arm crank ergometry in all men and during subma ximal wheelchair driving on a treadmill in four men. Power output duri ng wheelchair driving on a treadmill was measured. Static and dynamic elbow muscle strength was measured isokinetically. Results-POmax was s ignificantly lower (P < 0.001) for wheelchair driving (109 (31) W; mea n (SD)) than for arm ergometry (163 (49) W). There was a significant c orrelation between PO,, for arm crank ergometry and wheelchair driving (r = 0.73). There was no correlation between PO,, and elbow strength. The mechanical efficiency was constant for the different levels on th e arm crank ergometry test. The submaximal testing showed a consistent ly lower mechanical efficiency for wheelchair driving than for arm cra nk ergometry. Conclusions-It is suggested that the lower level of powe r output for wheelchair driving is fully explained by the lower mechan ical efficiency. Any improvement in power output available for ambulat ion must be based on wheelchair ergonomics.