Whole-body pre-cooling and heat storage during self-paced cycling performance in warm humid conditions

Abstract

The aim of this study was to establish the effect that pre-cooling the skin without a concomitant reduction in core temperature has on subsequent self-paced cycling performance under warm humid (31°C and 60% relative humidity) conditions. Seven moderately trained males performed a 30 min self-paced cycling trial on two separate occasions. The conditions were counterbalanced as control or whole-body pre-cooling by water immersion so that resting skin temperature was reduced by ≫5-6°C. After pre-cooling, mean skin temperature was lower throughout exercise and rectal temperature was lower (P ≪ 0.05) between 15 and 25 min of exercise. Consequently,heat storage increased (P ≪ 0.003) from 84.0±8.8 W·m^-2 to 153±13.1 W·m^-2 (mean±s _x ) after pre-cooling, while total body sweat fell from 1.7±0.1 l·h^-1 to 1.2±0.1 1·h^-1 (P ≪ 0.05). The distance cycled increased from 14.9±0.8 to 15.8±0.7km (P ≪ 0.05) after pre-cooling.The results indicate that skin pre-cooling in the absence of a reduced rectal temperature is effective in reducing thermal strain and increasing the distance cycled in 30 min under warm humid conditions.