The Effects of 3-weeks of Aerobic Exercise in Heat on Fitness and PGC1a in Females: 1070

The effects of exercise training in the heat have been well documented in men. However, the effects of exercise training in the heat in women have not received as much attention. We have previously reported a blunted rise in PGC1α in men after acute aerobic exercise in the heat. PURPOSE: To determine the impact of three weeks of aerobic exercise training in the heat compared to training in room temperature on thermoregulation, PGC1α mRNA response, and aerobic capacity in women. METHODS: Twenty-three untrained college aged females (24 ± 4 years old, 168 ± 5 cm tall, and weighed 67.3 ± 11.2 kg) were randomly assigned to 3 weeks of aerobic exercise training in either 20 °C (n = 12) or 33 °C (n = 11) environmental temperatures. RESULTS: VO2max in room temperature conditions increased with training (2.57 ± 0.35 to 2.71 ± 0.32 L·min-1, p = 0.01), but was not different between 20 °C or 33 °C training conditions (p = 0.821). HR decreased with training (152 ± 16 to 140 ± 0.13 bpm, p < 0.001), but was not different between 20 °C or 33 °C training conditions (p = 0.341). Sweat rate increased with training (0.655 ± 0.192 to 0.775 ± 0.212 L·hr-1, p = 0.006) and was higher in 33 °C (0.835 ± 0.144 L·hr-1) than 20 °C (0.605 ± 0.132 L·hr-1, p < 0.001). PGC1α mRNA increased with an acute exercise bout before (1.01 ± 0.10 to 4.96 ± 2.08 fold, p < 0.001) and after training (1.07 ± 0.10 to 3.21 ± 1.39 fold, p < 0.001) and had a smaller response after training than before training (p = 0.005). There were no differences in PGC1α mRNA between groups (p = 0.661). CONCLUSIONS: Women can increase aerobic fitness and maintain their exercise induced PGC1α mRNA response in the heat equally to that of room temperature conditions. This response contrasts with the blunted PGC1α mRNA response and VO2 max alterations previously observed in men.