Fluid intake during wheelchair exercise in the heat: effects of localized cooling garments.

BACKGROUND Wheelchair tennis players, competing in hot and humid environments, are faced with an increased risk of heat-related illness and impaired performance. This study examined the effects of head and neck cooling garments on perceptions of exertion (RPE), thermal sensation (TS), and water consumption during wheelchair exercise at 30.4 +/- 0.6 degrees C. METHODS Eight highly trained wheelchair tennis players (1 amputee and 7 spinal cord injured) completed two 60-min, intermittent sprint trials; once with cooling (COOL) and once without cooling (CON) in a balanced cross-over design. Players could drink water ad libitum at five predetermined intervals during each trial. Heart rate, blood lactate concentration, peak speed, TS, and RPE were recorded during the trials. Body mass and water consumption were measured before and after each trial. RESULTS Water consumption was lower in COOL compared with CON (700 +/- 393 mL vs. 1198 +/- 675 mL respectively; P = 0.042). Trends in data suggested lower RPE and TS under COOL conditions (N.S.). Total sweat losses ranged from 200 to 1300 mL; this equated to approximately 1% dehydration after water consumption had been accounted for when averaged across all trials. The ad libitum drinking volumes matched and, in some cases, were greater than the total sweat losses. CONCLUSIONS These results suggest that there is a counterproductive effect of head and neck cooling garments on water consumption. However, despite consuming volumes of water at least equivalent to total sweat loss, changes in body mass suggest an incidence of mild dehydration during wheelchair tennis in the heat.