Garver, M. J., Hovey, G., Nielsen, L., Dickinson, J., Melvin, N., Schaefer, T., Gee, D., Nethery, V., & Papadopoulos, C. (2007). Effect of glycerol hyperhydration on running performance in the heat. ACSM Annual Meeting New Orleans, Presentation Number 1868.

This study assessed the physiological and thermoregulatory effects of glycerol hyperhydration during a performance run in the heat. Trained runners (N = 6) performed two 10-km performance runs. Two and a half hours before a run, Ss ingested either a glycerol-electrolyte or carbohydrate-electrolyte solution followed by water (~1.95 liters).

Glycerol helped retain a significantly greater volume of water compared to the placebo condition. There was no significant difference between the two conditions for completion time, sweat loss, core temperature, or perceived exertion.

Implication. A carbohydrate-electrolyte solution was sufficient for maintaining enough water to curtail the effects of a hot and dry climate on a high intensity performance run. The extra volume of water associated with the glycerol condition added no additional thermoregulatory or physiological benefits.

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