Within-subject Variation of Thermoregulatory Responses during Repeated Exercise Bouts.

AIM: To assess the within-subject variation of thermoregulatory responses during 2 consecutive 15-km road races. Secondly, we explored whether gastrointestinal temperature (TGI) data from the first race could improve our previously established predictive model for finish TGI in the second race. METHODS: We measured TGI before and immediately after both races in 58 participants and determined correlation coefficients. Finish TGI in the second race was predicted using a linear regression analysis including age, BMI, pre-race fluid intake, TGI increase between baseline and the start of the race and finish TGI in the first race. RESULTS: Under cool conditions (WBGT 11-12 degrees C), TGI was comparable between both races at baseline (37.6+/-0.4 degrees C vs. 37.9+/-0.4 degrees C; p=0.24) and finish (39.4+/-0.6 degrees C vs. 39.4+/-0.6 degrees C; p=0.83). Finish TGI correlated significantly between both races (r=0.50; p<0.001). The predictive model (p