Cooling during exercise enhances performances, but the cooled body areas matter: A systematic review with meta-analyses.

ABSTRACT

INTRODUCTION: Hyperthermia during exercise induces central and peripheral fatigue and impairs physical performance. To facilitate heat loss and optimize performance, athletes can hasten body cooling prior (pre-cooling) or during (per-cooling) exercise. However, it is unclear whether per-cooling effect is the same on 'aerobic' and 'anaerobic' types of exercise (duration <75 and >76 seconds, respectively, according to Gastin [Sports Med 2001;31725-741]) and whether the body area that is cooled makes a difference. METHODS: A literature search led to the identification of 1582 potential studies. Included studies had to include physical exercise with sufficient details on the type, duration, intensity, and provide valid performance measures and a cooling intervention administered during exercise with sufficient details on the type and site of application. RESULTS: Forty-five studies were included. Per-cooling provides a performance benefit during 'aerobic' (standardized mean difference (SMD) of 0.60, P < .001) and 'anaerobic' exercises (SMD = 0.27, P < .02). The effects were greater during aerobic compared to anaerobic exercises (P < .01). Internal cooling (cold fluid ingestion such as cold water and ice slurry/menthol beverage) and external cooling (face, neck, and torso) provide the greatest performance benefit for 'aerobic' performance with a moderate to large effect (0.46 < SMD < 1.24). For 'anaerobic' exercises, wearing a whole-body cooling garment is the best way to enhance exercise performance (SMD = 0.39, P < .01). CONCLUSION: Per-cooling improves 'aerobic' and 'anaerobic' exercise performance with a greater benefit for 'aerobic' exercise. The magnitude of the effect depends on the type and site of the cooling application.