Thermoregulatory and physiological responses of wheelchair athletes to prolonged arm crank and wheelchair exercise.

Seven wheelchair athletes participated in this study. On separate occasions all athletes performed 60 min of arm crank ergometry and wheelchair ergometry at 60% of the ergometer specific VO2peak in cool conditions (21.5+/-1.3 degrees C; 54.2+/-6.3% relative humidity, 21.2+/-1.9 degrees C; 55.5+/-11.9% relative humidity, respectively). The order of testing was randomised. Aural and skin temperatures were continually measured throughout the 60 min test. Expired air was collected at 5, 15, 30, 45, and 60 min during the exercise period. Oxygen consumption was similar for both trials (1.09+/-0.21 and 1.16+/-0.331 x min-(-1), for the ACE and WCE trials, respectively). Heat storage was calculated at these time-points. Aural temperature was elevated from rest between 25 to 45 min of wheelchair ergometry (0.5+/-0.3 degrees C; P < 0.05) when compared to between 20 min of exercise and 5 min of recovery (0.6+/-0.3 degrees C; P<0.05) during the arm crank ergometry trial. On the cessation of arm crank ergometry, heat storage was elevated above values observed at 5 min of exercise (P < 0.05). On the cessation of wheelchair ergometry, heat storage was not elevated above values at 5 minutes of exercise. Upper arm skin temperature was cooler during wheelchair ergometry when compared to arm crank ergometry (P<0.05). All other skin temperature responses were similar during both exercise modes. The efficiency of arm crank ergometry was greater than wheelchair ergometry throughout the exercise period (18.5+/-3.5 % and 8.9+/-3.7% at 60 minutes of exercise, respectively; P < 0.05). The results of this study suggest that although ACE demonstrates greater efficiency than WCE prolonged arm crank ergometry elicited greater thermal and physiological strain when compared with prolonged wheelchair ergometry. The lower thermal strain during WCE was suggested to be related to the propulsion biomechanics which may result in some degree of local cooling, and consequently heat dissipation, when compared to ACE. Due to the greater thermal strain during arm crank ergometry, it is recommended that for studies examining the exercise responses of wheelchair users wheel-chair ergometry should be employed.