Physical and Perceptual Cooling with Beverages to Increase Cycle Performance in a Tropical Climate

Purpose: This study compares the effects of neutral temperature, cold and ice-slush beverages, with and without 0.5% menthol on cycling performance, core temperature (T-co) and stress responses in a tropical climate (hot and humid conditions). Methods: Twelve trained male cyclists/triathletes completed six 20-km exercise trials against the clock in 30.7 degrees C +/- 0.8 degrees C and 78%+/- 0.03% relative humidity. Before and after warm-up, and before exercise and every 5 km during exercise, athletes drank 190 mL of either aromatized (i.e., with 0.5 mL of menthol (5 gr/L)) or a non-aromatized beverage (neutral temperature: 23 degrees C +/- 0.1 degrees C, cold: 3 degrees C +/- 0.1 degrees C, or ice-slush: -1 degrees C +/- 0.7 degrees C). During the trials, heart rate (HR) was continuously monitored, whereas core temperature (T-co), thermal comfort (TC), thermal sensation (TS) and rate of perceived exertion (RPE) were measured before and after warm-up, every 5 km of exercise, and at the end of exercise and after recovery. Results: Both the beverage aroma (P<0.02) and beverage temperature (P<0.02) had significant and positive effects on performance, which was considerably better with ice-slush than with a neutral temperature beverage, whatever the aroma (P<0.002), and with menthol vs non-menthol (P<0.02). The best performances were obtained with ice-slush/menthol and cold/menthol, as opposed to neutral/menthol. No differences were noted in HR and T-co between trials. Conclusion: Cold water or ice-slush with menthol aroma seems to be the most effective beverage for endurance exercise in a tropical climate. Further studies are needed to explore its effects in field competition.