Effects of Passively Induced Hyperthermia on a Single Bout of Anaerobic Exercise


PURPOSE: The purpose of this pilot study was to establish a protocol to assess the effects of passively induced hyperthermia on the ability to produce and maintain a 30s-anaerobic bout of exercise. It was hypothesized that both Peak Power Output (PPO) and Mean Power Output (MPO) would decrease in hyperthermia when compared to normothermia. METHODS: The Simon Fraser University Office of Research Ethics approved the study. Prior to participating in the study, each volunteer was given a laboratory orientation, a 24 h reflection period, completed PAR-Q and medical history forms, and gave a signed, informed consent. Two healthy male volunteers aged 40 ±22.6 years (mean±SD) with a Body Mass Index of 24.0 ± 0.05 kg/m2 participated in the study. Esophageal Temperature (TES) was measured with a thermocouple probe inserted to the level of the left ventricle. Peak Power Output (PPO) and Mean Power Output (MPO) were measured on a Lode electrically-braked cycle ergometer. Each participant performed a 30s Wingate Anaerobic Test (WAnT) in one of two thermal states, normothermic or hyperthermic. Each volunteer was rendered hyperthermic in a warm bath. RESULTS: A paired two-tailed t-test was employed for differences in TES, PPO, and MPO between thermal states. The significance level was set at 0.05. TES was significantly higher (p< 0.05) at 38.15±0.06oC at the start of exercise in hyperthermia compared to normothermia 37.09±0.05oC. CONCLUSION: No significant changes in PPO was higher at 1074±182.4 Watts (W's) during normothermia compared to hyperthermia at 1013.5±205.8 W’s, the difference was not significant (p=0.17). MPO was higher at 583.5±106.8 W's during normothermia compared to hyperthermia at 570.5±135.1 W’s, however the difference was not significant (p=0.63). In conclusion, these preliminary results suggest passively reaching a hyperthermic core temperature has no effect on either PPO or MPO during a maximal anaerobic bout of exercise.

Supported by NSERC and CFI

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