Heat acclimation: practical and efficient in the laboratory

Abstract

Introduction

In order to be able to perform optimally in endurance competitions in hot and humid climates - such as the 2017 Mountain Bike World Championships in Cairns (AUS) - it is recommended that the athletes acclimatize to heat for about two weeks at the competition venue (Périard et al., 2015). With a short, "artificial" pre-acclimatization (acclimation) in the heat laboratory, the necessary acclimatization time at the competition venue could be shortened and the athletes thus offered valuable planning scope.

The aim of this study was to quantify the psycho-physiological acclimation effects during a week-long laboratory acclimation in elite mountain bikers.

Methods

Six participants of the Mountain Bike World Championships 2017 (4 f, 2 m; 3 U23, 3 Elite) trained for 6.7±1.6 days in the heat laboratory (67±12 min per day at ~31°C and ~78% rel. humidity). During the heat trainings heart rate, thermal stress sensation and sweat rate were recorded and acclimation effects were quantified using mixed linear models.

Results

Per acclimation day, a decrease in heart rate of 0.92 bpm (95%-CI: [0.34 bpm, 1.57 bpm]), a decrease in thermal stress sensation of 0.14 points (95%-CI: [0.11 points, 0.18 points]) and an increase in sweat rate of 31.4 ml/h (95%-CI: [-20.9 ml/h, 84.5 ml/h]) were observed with the same performance.

Discussion

The observed psycho-physiological effects of the one-week laboratory acclimation correspond to the expected effects of an equally long on-site acclimation (Périard, Racinais, & Sawka, 2015). This indicates that previous laboratory acclimatization can effectively shorten the necessary on-site acclimatization time and thus be used to individualize the acclimatization process.