Effect of a Cooling Kit on Physiology and Performance Following Exercise in the Heat

Exercising in the heat leads to an increase in body temperature that can increase the risk of heat illness or cause detriments in exercise performance.

To examine a phase change heat emergency kit (HEK) on thermoregulatory and perceptual responses and subsequent exercise performance following exercise in the heat.

Two randomized crossover trials that consisted of 30 minutes of exercise, 15 minutes of treatment (T₁), performance testing (5-10-5 pro-agility test and 1500-m run), and another 15 minutes of treatment (T₂) identical to T₁.

Outdoors in the heat (wet-bulb globe temperature: 31.5°C [1.8°C] and relative humidity: 59.0% [5.6%]).

Twenty-six (13 men and 13 women) individuals (aged 20-27 y).

Treatment was performed with HEK and without HEK (control, CON) modality.

Gastrointestinal temperature, mean skin temperature, thirst sensation, and muscle pain.

Maximum gastrointestinal temperature following exercise and performance was not different between trials (P > .05). Cooling rate was faster during T₁ CON (0.053°C/min [0.049°C/min]) compared with HEK (0.043°C/min [0.032°C/min]; P = .01). Mean skin temperature was lower in HEK during T₁ (P < .001) and T₂ (P = .05). T₂ thirst was lower in CON (P = .02). Muscle pain was lower in HEK in T₂ (P = .03). Performance was not altered (P > .05).

HEK improved perception but did not enhance cooling or performance following exercise in the heat. HEK is therefore not recommended to facilitate recovery, treat hyperthermia, or improve performance.