The effect of cooling prior to and during exercise on exercise performance and capacity in the heat: a meta-analysis

• Published in: British Journal of Sports Medicine 2015-01, Vol.49 (1), p.7-13
• Main Authors: Tyler, Christopher James, Sunderland, Caroline, Cheung, Stephen S
• Format: Article
• Language: English
• Subjects: Athletic Performance - physiology; Cold Temperature; Cooling; Environmental conditions; Exercise; Exercise - physiology; Heat; Hot Temperature; Human performance; Humans; Intervention; Methods; Physiology; Skin; Soccer; Studies; Temperature
• ISSN: 0306-3674; 1473-0480
• DOI: 10.1136/bjsports-2012-091739

Exercise is impaired in hot, compared with moderate, conditions. The development of hyperthermia is strongly linked to the impairment and as a result various strategies have been investigated to combat this condition. This meta-analysis focused on the most popular strategy: cooling. Precooling has received the most attention but recently cooling applied during the bout of exercise has been investigated and both were reviewed. We conducted a literature search and retrieved 28 articles which investigated the effect of cooling administered either prior to (n=23) or during (n=5) an exercise test in hot (wet bulb globe temperature >26°C) conditions. Mean and weighted effect size (Cohen's d) were calculated. Overall, precooling has a moderate (d=0.73) effect on subsequent performance but the magnitude of the effect is dependent on the nature of the test. Sprint performance is impaired (d=−0.26) but intermittent performance and prolonged exercise are both improved following cooling (d=0.47 and d=1.91, respectively). Cooling during exercise has a positive effect on performance and capacity (d=0.76). Improvements were observed in studies with and without cooling-induced physiological alterations, and the literature supports the suggestion of a dose–response relationship among cooling, thermal strain and improvements in performance and capacity. In summary, precooling can improve subsequent intermittent and prolonged exercise performance and capacity in a hot environment but sprint performance is impaired. Cooling during exercise also has a positive effect on exercise performance and capacity in a hot environment.