Casa, D. J., McClung, J. M., Knight, J. C., Goss, P. J., Hipp, G. R., Harvard, W. R., & Clements, J. M. (2000). Body cooling between two bouts of exercise in the heat enhances performance during the second bout. Medicine and Science in Sports and Exercise, 32(5), Supplement abstract 825.

Heat-acclimated runners (N = 15) completed a hilly trail run (~19 km; ~86 min) in the heat (27 degrees Celsius) at an individually selected comfortable pace on three occasions one week apart. Treatments were administered and completed 15 minutes before each trial. The treatments were as follows.

• Trail run followed by 12 minutes of ice water (5+ degrees Celsius) immersion (torso and upper legs) followed by a 3.2 km run in the heat.
• Trail run followed by 12 minutes of cold water (14+ degrees Celsius) immersion followed by a 3.2 km run in the heat.
• Trail run followed by 12 minutes of mock immersion (no water) followed by a 3.2 km run in the heat.

Cold-water immersion was found to produce performance and physiological improvements that were better than the ice-cold or mock-immersion treatments.

Implication. Rapid, but not radical, cooling can benefit a second performance in the heat.

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