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 ergome try at 60% of the ergometer specific (V)over dotO(2)peak in cool conditions (21.5 +/- 1.3 degrees C; 54.2 +/- 6.3% relative humidity, 21.2 +/- 1.9 deg rees C; 55.5 +/- 11.9% relative humidity, respectively). The order of testi ng was randomised. Aural and skin temperatures were continually measured th roughout the 60 min test. Expired air was collected at 5, 15, 30, 45, and 6 0 min during the exercise period. Oxygen consumption was similar for both t rials (1.09 +/- 0.21 and 1.16 +/- 0.33 I x min(-1), for the ACE and WCE tri als, respectively). Heat storage was calculated at these time-points. Aural temperature was elevated from rest between 25 to 45 min of wheelchair ergo metry (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 s torage was elevated above values observed at 5 min of exercise (P < 0.05). On the cessation of wheelchair ergometry, heat storage was not elevated abo ve values at 5 minutes of exercise. Upper arm skin temperature was cooler d uring wheelchair ergometry when compared to arm crank ergometry (P < 0.05). All other skin temperature responses were similar during both exercise mod es. The efficiency of arm crank ergometry was greater than wheelchair ergom etry throughout the exercise period (18.5 +/- 3.5% and 8.9 +/- 3.7% at 60 m inutes of exercise, respectively; P < 0.05). The results of this study sugg est that although ACE demonstrates greater efficiency than WCE prolonged ar m crank ergometry elicited greater thermal and physiological strain when co mpared with prolonged wheelchair ergometry. The lower thermal strain during WCE was suggested to be related to the propulsion biomechanics which may r esult in some degree of local cooling, and consequently heat dissipation, w hen compared to ACE. Due to the greater thermal strain during arm crank erg ometry, it is recommended that for studies examining the exercise responses of wheelchair users wheelchair ergometry should be employed.