Interactions between perceived exertion and thermal perception in the heat in endurance athletes

Introduction: The study aimed to investigate how a distortion of perceived exertion in the heat may affect, during a self-paced cycling exercise preceded by prior cognitive task, the thermal perception and the subsequent regulation of power output in high level athletes. Methods: Eleven endurance trained male athletes completed four experimental sessions including a 30-min fixed-RPE (15-Hard) cycling exercise in neutral (TMP-22 degrees C) and hot (HOT-37 degrees C) conditions, following a 60-min incongruent Stroop task (EXP) or passively watching documentary films (CON). Central and peripheral performances of the knee extensors were assessed before the cognitive task and after the exercise. Results: Although mental demand and effort were higher in EXP (P < 0.05), no effect of prior cognitive task was observed on subjective feelings of mental fatigue or decline in power output at a fixed RPE. Average exercise intensity was lower in HOT than TMP (3.14 +/- 0.09 W.kg vs. 3.42 +/- 0.10 W.kg(-1) respectively, P < 0.05). Skin temperature and warmth sensations were higher in HOT throughout the exercise (P < 0.05) but not thermal comfort. Central and peripheral parameters were not affected more in HOT than in TMP. Conclusion: Although the effects of combined stressors on the distortion of perceived exertion could not be verified, the greater decline in power output recorded in HOT than TMP suggest a high contribution of both perceptual and cardiovascular responses in the regulation of work rate when the subject is in mild hyperthermia.