Objective: This study probes into college students' heat accommodate ability and physiological changes when they exercise under heat environment. Methods: 18 healthy male volunteers were randomly assigned into heat environment exercise group (HE) and normal environment exercise group (NE). The two groups were required to perform 60 min cycling exercise by 55% (V) over dotO(2)max intensity in environment of 38 +/- 1 degrees C and 26 +/- 1 degrees C respectively (73%+/- 3% Relative Humidity). The subjects' heart rate (HR), Ratings of Perceived Exertion (RPE) and rectal temperature (T-re) were recorded every 15 min, and the Pearson coefficient of HR and RPE under the heat environment was calculated. Meanwhile, the weight loss, total sweat volume, total sweat loss rate, blood urea and fatigue index (F1) of the two groups before and after protocol exercises were noted. Results: There's no significant difference of HR and RPE in first 15 min between the two groups. But after subjects exercise 30 min, HE's HR, RPE score is significantly higher than NE's, and this trend is preserved until finish. There's affinity coefficient between HR and RPE (R=0.839, P<0.05). In initial stages of exercise, NE's T is lower than HE's, and the difference become more obvious after 30 min. The weight loss, total sweat loss rate and total sweat loss volume of NE group's is Ins than HE group's respectively (P<0.05). Similarly, NE's blood urea nitrogen (BUN) and F1 is significantly lower than HE's. Conclusion: There's more profound effect on the marker of HR, RPE, T-re when subjects exercise under heat environment. And the subjects si:em apt to get fatigue and weight loss, dehydrated.
