Sadie N. Carrillo1, Eder Pina1, Christina A. Buchanan1, Lance C. Dalleck1. Quantifying Heat Stress of Sauna Suits during Physical Activity and Examining the Effects of Heat Acclimation on Physiological Responses in Hypoxic Conditions: a Preliminary Explorative Study on Cross-Adaptation. 1High Altitude Exercise Physiology Program, Western Colorado University, Gunnison, CO, USA.
Purpose: The purpose of this study was two-fold: to analyze thermal stress of sauna suits during low-moderate exercise; and to examine the effects of a two-week heat acclimation training with a sauna suit on physiological responses in hypoxic conditions in active males. Methods: 4 physically active males (M=24 ± 2.7 yrs) completed a two-week, heat acclimation period using a sauna suit. Hypoxic testing took place pre- and post- heat acclimation, involving 30 minutes of sitting while being exposed to simulated altitude (~4000 meters). Heart rate (HR), oxygen saturation (SpO2), blood pressure (BP), and symptoms of Acute Mountain Sickness were all measured. Subjects also completed 2 thermal stress tests, involving jogging for 45 minutes at their Ventilatory Threshold-1 with and without a sauna suit. Core temperature, HR, and SpO2 were measured during the thermal stress tests. Results: Significant differences (p<0.05) were found for mean arterial pressure comparing pre- to post- hypoxic tests with an average improvement of 9.22 ± 5.18 mm/Hg. No statistical mean differences were found for the other variables measured during the hypoxic tests, even though they all improved post- heat acclimation. Significant differences were found for area under the curve for core temperature comparing thermal stress test trials with an average increase in area under the curve of 42.53 ± 16.16 °F/min. There were no significant main effects for the other variables measured during the thermal stress tests but did show decrements that are expected with heat exposure. Conclusion: The results of this novel study support the use of a sauna suit as a form of heat acclimation to enhance physiological responses at altitude.