Deception of ambient and body core temperature improves self-paced cycling in hot, humid conditions

The central governor model of exercise performance is proposed to act through anticipatory regulation of exercise, to prevent cellular damage, maintain a physiological reserve capacity (St. Clair Gibson and Noakes 2004, British Journal of Sports Medicine, 38, 797-806), and is particularly evident in the heat (Tucker, et al. 2006 Journal of Physiology, 574, 905–915). Instead, Marcora, et al. (2009 Journal of Applied Physiology. 106, 857-864) propose that the conscious perception of effort (RPE) is a greater influence over exercise performance. As RPE can be manipulated by deception of exercise duration (Baden, et al. 2005 British Journal of Sports Medicine, 39(10):742-746), the purpose of this study was to test the hypothesis that, deception of ambient and core temperature would alleviate the decrement in cycling performance in the heat. Seven males completed three 30 min cycling time trials in a randomised order on a Kingcycle ergometer in this study that was ethically approved. One time trial was in temperate, control conditions (CON, mean 21.8, s = 0.6 oC; mean 43.3, s = 4.3 %rh), the others in hot, humid conditions (HOT; mean 31.4, s = 0.3 oC; mean 63.9, s = 4.5 %rh). In one of the hot, humid conditions (mean 31.6, s = 0.5 oC; mean 65.4, s = 4.3 %rh), participants were deceived (DEC) into thinking the ambient conditions were 26.0 oC; 60.0 %rh and their core temperature was 0.3oC lower than it really was. Compared to CON (mean 16.63, s = 2.43 km) distance covered was lower in HOT (mean 15.88, s = 2.75 km; P = 0.038), but DEC ameliorated this (mean 16.74, s = 2.87 km; P < 0.024). Mean power output was greater in DEC (mean 184.4, s = 60.4 W) than HOT (mean 168.1, s = 54.1 W; P < 0.038) and no difference was observed between CON and DEC. Rectal temperature and iEMG of the vastus lateralis were not different between any condition. During the warm up, RPE was higher than CON in HOT only (P = 0.036). Further, RPE in the third minute of the time trial was lower in DEC than HOT (P = 0.028). The results suggest that deception of the true body core and ambient temperatures, so that participants thought they were cooler and exercising in a cooler environment, improved cycling performance in the heat. Deception lowered RPE during the warm up and start of the time trial, suggesting the initial period of exercise is an important time for establishing the perceived exertion of the task. Further, deception can be used to manipulate the perceived and actual demand of an exercise task to improve cycling time trial performance in hot, humid conditions.