Endurance exercise induces hyperthermia and increases physiological strain. When a warm environment is added these variables are further affected and so is performance. Nevertheless, the effects of pre-exercise cooling in these responses remain unclear, be it in a warm or thermoneutral environment. Therefore, the aim of this study was to investigate the effects of a pre-exercise whole-body cooling method on physiological strain and performance during a 30km time trial cycling in two environments. Methods: 8 male cyclists (mean±SD: 28.8±2.7 years; 72.7±8.4 kg; 9.7±2.4 % body fat; 58.2±11.0mlO2/kg/min) performed, in a randomized balanced order, four 30km time trials in an environmental chamber set at: warm (35°C; 68%RH) and thermoneutral (24°C, 68%RH). In two trials, the exercise was preceded by a whole-body water immersion (24°C) until rectal temperature (Tre) decreased 0.4°C compared to rest value. The exercise was then performed either in the warm (PREC35) or the thermoneutral (PREC24) environment. The other two trials were the control conditions, and exercise was performed without the cooling procedure (CON24 and CON35). Throughout the exercise protocols the subjects` Tre, heart rate (HR) and thermal comfort were measured every 2km and they were allowed water ad libitum. Data was analyzed using a 3-way ANOVA with repeated measures and Tukey`s post-hoc test (STATISTICAL 7.0 Program). Values are reported as mean±SD. Results: Subjects` performance was significantly impaired in the heat (p<0.05), and was not affected by pre-cooling (p=0.063) (PREC24= 54.7±4.4min; CON24= 56.0±4.0min; PREC35= 59.6±3.4min; CON35= 61.0±3.4min). Tre was affected both by the environmental conditions and by the pre-cooling (PREC24= 36.4±0.3°C at 0km; 38.7±0.3°C at 30km; CON24 = 37.0±0.2°C at 0km; 38.7±0.4°C at 30km; PREC35=36.3±0.5°C at 0km; 39.0 ± 0.4°C at 30km; CON35= 37.2±0.2°C at 0km; 39.7±0.5°C at 30km). HR was significantly lower pre-exercise in the pre-cooling conditions but was not affected by the environmental conditions. In the thermoneutral environment subjects` reported a better thermal comfort but this variable was not affected by the pre-cooling procedure. Conclusion: The pre-cooling method was not sufficient to improve performance on a 30km time trial cycling in a thermoneutral or warm environment conditions, despite the reduced Tre observed in the pre-exercise cooling conditions.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Veröffentlicht von Vrije Universiteit Brussel. Alle Rechte vorbehalten.