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

CONTEXT: 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.

OBJECTIVE

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

DESIGN

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.

SETTING

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

PARTICIPANTS

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

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

MAIN OUTCOME MEASURES: Gastrointestinal temperature, mean skin temperature, thirst sensation, and muscle pain.

RESULTS

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).

CONCLUSIONS

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.