Precooling does not Enhance the Effect on Performance of Midcooling with Ice-Slush/Menthol

Abstract

This study investigated whether the combination of internal precooling (PC) and internal midcooling (MC cooling during exercise) would enhance performance more than MC alone. 9 trained males completed two 30-km cycling trials in a hot and humid environment (WBGT: 29±0.7°C, 80±0.02% relative humidity). For 30 min before exercise, the subjects sat quietly and drank water at 23°C (MC) or 3°C (PC+MC). During the MC and PC+MC time trials, they drank an ice-slush/menthol beverage (i. e., 0.025% menthol). Trial time, gastrointestinal temperature (T_co ), heart rate (HR), rating of perceived exertion (RPE), thermal sensation (TS), and thermal comfort (TC) were assessed. Trial time was not significantly different (P>0.05) between MC and PC+MC (3 737±552 s and 3 815±455 s). Before exercise, T_co was lower with precooling (37.0±0.3°C; P<0.02). During exercise, no between-trial differences were noted for T_co, HR, RPE, TC or TS, but RPE was significantly lower with PC+MC in the latter stages (P<0.05). (1) Cold beverage intake before exercise did not improve the subsequent exercise performance with ice-slush/menthol beverage intake, and (2) despite no improvement in performance, RPE declined in the latter stages of exercise in the condition of PC+MC, suggesting that this combination might be beneficial for longer exercise.