Differences of Perceived Exertion, Thermal Sensation, Sweating, and Skin Temperature During Exercise in a Hot and Humid Environment by Evaporative Cooling Methods

OBJECTIVES This study aimed to examine the effects of evaporative cooling methods of ethanol or water sprays on Ratings of Perceived Exertion (RPE), Thermal Sensation (TS), Skin Temperature (ST), Tympanic Temperature (TT), and sweat loss during exercise in a hot and humid environment. METHODS Nine healthy men (24.1 ± 2.5 years, 70.3 ± 3.2 kg, 172.8 ± 2.5 cm) participated in three test conditions: Non-Spray (NS), Water Spray (WS), and Ethanol Spray (ES). All participants underwent 10 minutes of heat acclimation prior to each exercise session, then ran on a treadmill at 70% of their maximal aerobic capacity for 20 minutes in a chamber maintained at 29-31℃ and 75-85% relative humidity. Naked body weight and TT were measured before and after each trial. At 3 minutes after exercise onset, WS or ES was sprayed onto the skin in the corresponding conditions. Two minutes after spraying, ST was measured. This procedure was repeated four times during the exercise. Spray was applied evenly to the neck, chest, arms, and thighs using 3.0-3.5 mL per area, keeping a distance within 10 cm. RPE and TS were assessed before and after exercise in all conditions. RESULTS There were no significant differences in RPE, TS, and TT between conditions. Sweat rate and skin temperature were lower in the ES group compared to the other groups and showed significant differences between conditions and measuring time points (p < 0.05). CONCLUSIONS The results indicated that there were no significant differences in Ratings of Perceived Exertion, Thermal Sensation, and Tympanic Temperature between conditions. But ES induced a lower Skin Temperature and sweat loss over NS and WS. Although further studies are necessary, the results demonstrated a potential feasibility of ethanol spray for application.