Scheadler, C. M. Garver, M. J., DiGeronimo, M. K., Huber, C. M., Kirby, T. E., & Devor, S. T. (June 02, 2010). Glycerol hyperhydration and endurance running performance in the heat. Presentation 1682 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

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This study tested glycerol hyperhydration against water hyperhydration on the ability to reduce cardiovascular and thermal strain and improve performance when Ss ran a set distance as quickly as possible. It was hypothesized that compared with water hyperhydration, glycerol hyperhydration would result in: a) greater fluid retention, b) no differences in heart rates and core temperatures, and c) decreased run time performances. Male endurance trained runners (N = 6) completed a treadmill run in an environmental chamber at a self-selected pace, estimated to take one hour. Temperature was set at 30C with 50% relative humidity. Beginning 2.5 hours before exercise, glycerol was given at 1.2 g/kgBW with a total fluid ingestion of 26 ml/kgBW. The placebo condition involved ingesting water of an equal amount. Runners ingested up to 500 ml during the run and were unable to see their elapsed time or chosen speed; only distance covered.

Fluid retention and time to complete the run were no different between the treatments. Heart rate, core temperature, and rating of perceived exertion were no different between trials at any distance during the run.

Implication. For a run lasting 68 minutes in hot conditions, glycerol hyperhydration was no more beneficial than water hyperhydration for altering cardiovascular strain, thermal strain, or running performance.

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