School of Sport Science, Exercise and Health, University of Western Australia , Crawley, WA, Australia.
J Sports Sci Med. 2013 Sep 1;12(3):565-70. eCollection 2013.
Whether precooling is beneficial for exercise performance in warm climates when heat acclimatised is unclear. The purpose of this study was to determine the effect of precooling on repeat-sprint performance during a simulated team-sport circuit performed outdoors in warm, dry field conditions in seasonally acclimatised males (n = 10). They performed two trials, one with precooling (PC; ice slushy and cooling jacket) and another without (CONT). Trials began with a 30-min baseline/cooling period followed by an 80 min repeat-sprint protocol, comprising 4 x 20-min quarters, with 2 x 5-min quarter breaks and a 10-min half-time recovery/cooling period. A clear and substantial (negative; PC slower) effect was recorded for first quarter circuit time. Clear and trivial effects were recorded for overall circuit time, third and fourth quarter sprint times and fourth quarter best sprint time, otherwise unclear and trivial effects were recorded for remaining performance variables. Core temperature was moderately lower (Cohen's d=0.67; 90% CL=-1.27, 0.23) in PC at the end of the precooling period and quarter 1. No differences were found for mean skin temperature, heart rate, thermal sensation, or rating of perceived exertion, however, moderate Cohen's d effect sizes suggested a greater sweat loss in PC compared with CONT. In conclusion, repeat- sprint performance was neither clearly nor substantially improved in seasonally acclimatised players by using a combination of internal and external cooling methods prior to and during exercise performed in the field in warm, dry conditions. Of practical importance, precooling appears unnecessary for repeat-sprint performance if athletes are seasonally acclimatised or artificially acclimated to heat, as it provides no additional benefit. Key PointsPre-cooling did not improve repeated sprint performance during a prolonged team-sport circuit in field conditions.If individuals are already heat acclimatised/acclimated, pre-cooling is unnecessary for performance enhancement.Acclimation/acclimatisation seems to be the more powerful method for protecting against heat strain.
在热适应的情况下，预冷是否有利于在温暖气候下进行运动表现尚不清楚。本研究的目的是确定预冷对在温暖干燥的野外环境中进行的模拟团队运动循环中重复冲刺表现的影响，研究对象为季节性适应的男性（n=10）。他们进行了两次试验，一次是预冷（PC；冰沙和冷却夹克），另一次是不预冷（CONT）。试验开始时进行了 30 分钟的基线/冷却期，然后进行了 80 分钟的重复冲刺协议，包括 4 x 20 分钟的四分之一，2 x 5 分钟的四分之一休息和 10 分钟的中场休息/冷却期。第一季度电路时间记录到了明显而实质性的（负面；PC 较慢）效果。整体电路时间、第三和第四季度冲刺时间和第四季度最佳冲刺时间记录到了明显而微不足道的效果，其余性能变量记录到了不明确而微不足道的效果。在预冷期和第 1 季度结束时，核心温度略低（Cohen's d=0.67；90%置信区间=-1.27，0.23）。平均皮肤温度、心率、热感觉或感知用力程度没有差异，但中等 Cohen's d 效应大小表明 PC 组的出汗量比 CONT 组更大。总之，在温暖干燥的野外环境中进行运动时，使用内部和外部冷却方法进行预冷和运动期间，季节性适应的运动员的重复冲刺表现既没有明显改善，也没有实质性改善。从实际重要性来看，如果运动员已经适应了热或人为适应了热，预冷对重复冲刺表现没有额外的好处，因此预冷对于重复冲刺表现来说似乎是不必要的。主要观点预冷不能提高在野外条件下进行的长时间团队运动循环中的重复冲刺表现。如果个人已经适应了热或适应了热，预冷对于提高表现就没有必要了。适应似乎是防止热应激的更有效方法。
