Progressive Versus Traditional Heat Acclimation On Intermittent Sprint Exercise In The Heat: International Convention on Science, Medicine in Sport, Glasgow

Traditional heat acclimation protocols apply constant heat stress and exercise intensity on a number of days to elicit adaptation. Accordingly, heat strain progressively declines across the protocol potentially limiting performance in intermittent sprint exercise where high levels of thermal strain are observed. The purpose of this study was to compare a progressive heat acclimation protocol with a traditional protocol, matched for heat stress on markers of heat adaptation and intermittent sprinting in the heat. Eighteen games players matched for VO2max, peak power and body surface area were divided into three groups; progressive heat acclimation [PA, 4 d 30°C 50% relative humidity (RH), 4 d 33°C 53% RH and 4 d 35°C 60% RH], traditional heat acclimation (TA, 12 d 33°C 56% RH), and control (CT 12 d 19°C 36% RH). Pre and post acclimation, subjects completed a 40 min cycling intermittent sprint protocol (CISP) in 33°C 50% RH, comprising twenty, 5 s sprints. Heat acclimation reduced resting rectal temperature (Tre) prior to the CISP in PA (P0.05) but not in CT. Mean resting heart rate was reduced in PA (P< 0.05), but were not different after PA or CT. Perceived Exertion was reduced in the CISP after PA and TA, but not CT, while Thermal Sensation was reduced after PA only (P<0.05). Although improvements in physiological strain and perceptual measures were observed in the CISP after PA compared to TA, this did not translate to improved sprint exercise performance.