Morrison, S. A., Cotter, J. D., & Cheung, S. S. (2006). Are the benefits of pre-cooling overestimated? Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 827.

This study determined the metabolic, work, and body heat storage effects of pre-cooling and airflow (forced evaporative/convective cooling) on cycling performance in a hot environment. Healthy men (N = 10) completed four experimental trials in balanced order: 1) no pre-cooling before exercise, no wind during exercise (control); 2) no pre-cooling, wind velocity ~4.8 m/s during exercise; 3) pre-cooling, no wind; and 4) pre-cooling plus wind. Pre-cooling was via chest-deep water immersion (~24°C) for either one hour or until core temperature decreased by 0.5°C. Participants then cycled at 95% ventilatory threshold in a hot environment (30°C, 50% RH) until either volitional exhaustion, core temperature exceeded 39.5°C, or 95% maximum heart rate.

Endurance time was extended by 30 + 23 minutes with airflow and 16 +15 min with pre-cooling relative to the control condition. There was no added advantage by combining the two cooling procedures. Wind alone had a greater effect on heat removal than pre-cooling.

Implication. Pre-cooling can be an effective means of increasing overall work, although similar or better benefits can be achieved by providing adequate convective cooling during laboratory exercise in the heat.

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