International journal of sports physiology and performance | 2019
The Influence of Heat Acclimation and Hypohydration on Post-Weight-Loss Exercise Performance.
Abstract
PURPOSE\nThis study examined the influence of: i) fluid intake on heat acclimation and ii) the subsequent effects on exercise performance following acute hypohydration.\n\n\nMETHODS\nParticipants were randomly assigned to one of two groups, either able to consume water ad libitum (n = 10; age 23 ± 3 y; height 1.81 ± 0.09 m; body mass 87 ± 13 kg; HAW) or not allowed fluid (n = 10; age 26 ± 5 y; height 1.76 ± 0.05 m; body mass 79 ± 10 kg; HANW) throughout 12 x 1.5 h passive heat acclimation sessions. Experimental trials were completed on two occasions prior (two baseline trials) and one following the heat acclimation sessions. These sessions involved 3 h of passive heating (45°C, 38% relative humidity) to induce hypohydration followed by 3 h of ad libitum food and fluid intake after which participants performed a repeat sled-push test to assess physical performance. Urine and blood samples were collected before, immediately and 3 h following hypohydration to assess hydration status. Mood was also assessed at the same time-points.\n\n\nRESULTS\nNo meaningful differences in physiological or performance variables were observed between HANW and HAW at any time-point. Using pooled data, mean sprint speed was significantly (P<0.001) faster following heat acclimation (4.6±0.7 s compared to 5.1±0.8 s). Further, heat acclimation appeared to improve mood following hypohydration.\n\n\nCONCLUSIONS\nResults suggest passive heat acclimation protocols may be effective at improving short duration repeat-effort performance following acute hypohydration.