Sawka, M. N., Latzka, W. A., Montain, S. J., Skrinar, G. S., Fielding, R. A., & Pandolf, K. B. (1997). Hyperhydration: Thermal and cardiovascular effects during uncompensable exercise-heat stress. Medicine and Science in Sports and Exercise, 29(5), Supplement abstract 760.

The effects of glycerol and water hyperhydration during uncompensable exercise-heat stress were examined.

Hyperhydration (pre-exercise for one hour) consisted of 29.1 ml/kg lean body mass of water with or without glycerol (1.2 g/kg lean body mass) and was compared to euhydration (adequate fluid replacement during exercise). Uncompensable exercise-heat stress was a condition where evaporative heat loss required to maintain steady-state core temperature was inadequate.

It was found that hyperhydration was no more beneficial than concurrent fluid replacement during exercise in excessive heat stress.

Implication. Hyperhydration provides no exercise benefit over on-going fluid replacement in excessively hot conditions.

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