Institute of Tropical Medicine, Nagasaki University
Abstract
High intensity exercise in the heat causes major alterations in the circulatory and thermoregulatory functions resulting in reduced athletic performance. We investigated whether fluid ingestion during intermittent high intensity swimming exercise in warm water can mitigate adverse thermoregulatory and cardiovascular responses, and improve athletic performance. To do this, eight male college swimmers aged 22.8±1.0 yr, body weight 66.72±1.63kg and height 171.7±0.7cm were used. In a cross-over design, all eight subjects performed 20 sessions of intermittent 50m swims with a 1 min interval between each session when they were water replete (WR) or water deprived (WD). Oral temperature (To), heart rate (HR), plasma osmolarity (Posm), sweat water loss (SWL) and rating of perceived exertion (RPE) as well as swimming velocities (SV) were measured. No difference were observed in To, HR, SWL, and Posm between WR and WD conditions. However, WR maintained higher SV and lower RPE. In a second experiment involving a second set of college swimmers, a strong positive correlation was observed between SV and SWL (r=0.881, p<0.05). These findings reveal that during short duration high intensity intermittent swimming exercise lasting～12 mins, fluid intake did not influence cardiovascular and thermoregulatory responses, but improved athletic performance
