High-intensity Interval Exercise While Wearing A Sauna Suit Increases Energy Expenditure

Abstract

PURPOSE: The use of sauna suits (SS) has increased and claims to enhance weight loss and body temperature during exercise. Whether high-intensity interval exercise (HIIE) with a SS enhances energy expenditure (EE) and excess post-exercise oxygen consumption (EPOC) is unknown. The purpose of this study was to examine changes in EE and EPOC in response to HIIE while wearing a SS. METHODS: Seven recreationally active men and women (mean age, mass, and VO2max = 29.7 ± 6.9 yr, 68.8 ± 17.3 kg, and 46.2 ± 8.10 mL/kg/min, respectively) initially completed assessment of resting metabolic rate (RMR) and maximal oxygen uptake (VO2max). During the VO2max test, exercise began at 60 W for two minutes and work rate increased 25 - 30 W/min until volitional fatigue. Heart rate (HR) and breath-by-breath gas exchange were continuously measured. At least 48 hr later, subjects completed HIIE consisting of 10 x 1 min intervals at 85% peak power output, followed by 75 s of active recovery, with or without a SS. During exercise, HR, core temperature (Tc), and gas exchange data were continuously measured, and thermal sensation and rating of perceived exertion (RPE) were also recorded. For 1 hr post-exercise, subjects rested while changes in EPOC, Tc, and HR were determined. Blood lactate concentration was measured pre-exercise, 5 min post-exercise, and 1 hr post-exercise. Subjects returned 1 wk later and completed the other condition whose order was randomized RESULTS: Compared to no SS (NSS), total VO2 (57.3 ± 13.8 L vs. 60.4 ± 13.5 L, p = 0.028) and EE (286.8 ± 69.2 kcal vs. 302.0 ± 67.3 kcal, p = 0.048) were significantly higher for SS. However, EPOC was not significantly different 1 hr post-exercise between NSS (5.1 L ± 4.3 L) and SS (7.5 L ± 5.1, p = 0.16). End-exercise HR was not different between conditions (p = 0.42), but Tc was significantly higher (p = 0.046) for SS (38.6 ± 0.5 °C) compared to NSS (38.4 ± 0.4 °C). Post-exercise blood lactate concentration was not significantly different (p = 0.20) between conditions (9.6 ± 3.5 vs. 10.8 ± 3.4 in NSS vs. SS). End-exercise thermal sensation (p = 0.60) and RPE (p = 0.17) were not significantly different between conditions. CONCLUSIONS: Wearing a SS during HIIE elicits greater EE and Tc versus not wearing a SS. Therefore, a SS may aid in weight loss by increasing the total amount of calories expended during HIIE.