Head pre-cooling improves 5-km time-trial performance in male amateur runners in the heat.

Abstract

This study aimed to evaluate the effect of head pre-cooling on the 5-km time-trial performance of amateur runners in the heat. In a counterbalanced design, 15 male amateur runners (22.6±3.5y; VO2 max in heat 42.3±4.4mLO2 /kg/min) completed two 5-km time trials performed in the heat (35°C, 50% relative humidity). In one trial (HCOOL), participants underwent 20min of head cooling in a temperate environment (23°C, 70% relative humidity) prior to exercise. In another trial (CON), exercise was preceded by 20min of rest under the same temperature conditions. Exercise time was shorter in HCOOL (25min and 36s±3min) compared to CON (27±3min; p=0.02). Rectal temperature was reduced during the pre-exercise intervention in HCOOL (p<0.001), but not in CON (p=0.55). Relative changes in rectal temperature and mean head temperature were lower throughout HCOOL when compared with CON condition (p=0.005 and p=0.022, respectively). Mean skin temperature, heart rate, and rating of perceived exertion did not differ between HCOOL and CON conditions throughout exercise (p=0.20, p=0.52 and 0.31, respectively). Thermal comfort was lower in HCOOL condition in pre-exercise (p=0.014) with no differences observed throughout exercise (p=0.61). 5-km running performance in a hot environment was improved after a 20-min head cooling intervention, suggesting that this method may be practical as pre-cooling strategy and easily administered to both professional and amateur runners alike.