Responses of Obese and Non-obese Boys Cycling in the Heat

This study compared rectal temperature (T re), heat sensation and sweating between obese and non-obese boys during cycling in the heat. Participants (aged 12-15 years) were 17 obese and 16 non-obese (BMI = 29.4+/-4.3 and 16.8+/-1.7 kg.m(-2), respectively) boys. They cycled for 30-min (50-55% VO2peak) in a climatic chamber (35 degrees C, 45% RH) and T re, heat sensation and sweat volume were monitored. From the start to the end of cycling, T re was similar between the obese (37.4+/-0.3-37.8+/-0.3 degrees C) and non-obese (37.3+/-0.2-37.9+/-0.2 degrees C) groups. Heat sensation was higher in the obese group from the start (3.6+/-2.7 vs. 1.3+/-1.4 cm; P=0.008) to the end (7.6+/-2 vs. 5.2+/-2.2 cm; P=0.003) of cycling. Sweat volume corrected by body surface area was similar between the obese (200+/-123 mL.m(-2)) and non-obese (212+/-80 mL.m(-2)) groups. Initial and final HR were similar in both groups, and RPE was higher in the obese group at 25th (P=0.040) and 30th (P = 0.019) min. In conclusion, the obese pubescent participants presented similar T re and sweating volume, but higher heat sensation while cycling in the heat.