Cooling during Exercise in Temperate Conditions: Impact on Performance and Thermoregulation

Exercise-induced increase in core body temperature may lead to the development of hyperthermia (>40.0 degrees C) and/or decreased performance levels. This study examined the effects of wearing a cooling vest during a 5-km time trial on thermoregulatory responses and performance. 10 male masters athletes (42 +/- 10 years) performed a 5-km time trial on a motorized treadmill in a climate chamber (25 degrees C, 55 % relative humidity) with and without a cooling vest. Split times, heart rate, core-, skin- and cooling vest temperature were measured every 500 m. Subjects also rated thermal comfort and level of perceived exertion. The cooling vest significantly decreased heart rate (p < 0.05), decreased skin temperature (p < 0.001) and improved thermal comfort (p < 0.005) during the time trial. Time to finish the 5-km time trial and pacing strategy did not differ between the control (1 246 +/- 96 s) and cooling vest condition (1 254 +/- 98 s, p = 0.85). Additionally, thermoregulatory responses, maximum core body temperature and level of perceived exertion were not different across conditions (p = 0.85, p = 0.49, p = 0.11, respectively). In conclusion, we demonstrated that wearing a cooling vest during exercise improves thermal comfort but does not enhance performance or decrease core body temperature in male masters athletes under temperate ambient conditions.