Effectiveness of skin-heating using a water-perfused suit as passive and post-exercise heat acclimation strategies.

Abstract

The purpose of the present study was to evaluate the effectiveness of passive and post-exercise heat acclimation strategies through directly heating the skin with a water-perfused suit. Nineteen young males participated in the heat acclimation (HA) protocols for 10 days, which were conducted at an air temperature of 33oC with 60%RH. The exercise-only condition (N=6) conducted 1-h treadmill walking (6km·h-1) followed by 1-h rest. The post-exercise passive-heating condition (N=6) wore the suit (inflow water temperature 44.2oC) for 1-h after 1-h walking. The passive-heating condition (N=7) donned the suit for 2h. Heat tolerance tests (leg immersion in 42oC water for 60min) were conducted before and after the training to evaluate changes due to the 10-day intervention. Reflecting that suit-wearing for 10 days as both passive and post-exercise HA strategies can effectively induce adaptive changes, significant interaction effects appeared in: increase or decrease in mean skin temperature (P<0.05) and elevation in whole-body sweat rate (P<0.05). Reduction in rectal temperature (P<0.05) and blood pressure (P<0.05) were found most prominently in the passive-heating condition. These results indicate that this new method of heat acclimation training, donning a skin-heating water-perfused suit, can generate thermoregulatory benefits. The passive HA intervention could be applied to individuals for whom doing exercise regularly are not feasible.