Reduction in body temperature using hand cooling versus passive rest after exercise in the heat

Objectives To examine the effects of hydration and hand cooling on lowering body temperature after exercise in the heat. Design Randomized cross-over design. Methods Nine recreationally active male participants (mean ± SD; age, 24 ± 4; height, 177.3 ± 9.9 cm; body mass, 76.7 ± 11.6 kg; body fat, 14.7 ± 5.8%) completed a bout of treadmill exercise in a hot environment. After completion of exercise, participants were assigned to the following trials for post-exercise cooling: (1) hydrated with passive rest (HY), (2) hydrated with hand cooling on both hands (HY + 2HC), (3) dehydrated with passive rest (DY), and (4) dehydrated with hand cooling on both hands (DY + 2HC). Within subject differences were assessed using a three-way (Hydration × Condition × Time) repeated measures ANOVA with Tukey's post hoc analysis if significant interactions were found. Results Irrespective of hydration status, hand cooling on both hands resulted in significantly greater reductions in T _REC than passive cooling at minute 20 (0.27°C [0.05, 0.49], ES = 2.08, p = 0.017) (Fig. 1). The reduction in T _REC at minute 18 trended towards statistical significance (0.21°C [.003, .42], ES = 1.59, p = 0.053). Hydration status alone and when differentiated among modes of cooling showed no differences on changes of T _REC or heart rate across all conditions during post exercise recovery (p > 0.05). Conclusions Hand cooling on both hands reduced T _REC more than passive cooling, however, the cooling rates observed render hand cooling a poor option for cooling. Greater reductions in T _REC after exercise or between bouts of exercise may enhance recovery and subsequent performance.