Collins, M. G., Dolny, D. D., Gabel, K., Stephens, B., & Ryan, C. (2000). Effects of three hyperhydration solutions on cardiovascular and thermoregulatory responses, blood volume and running performance. Medicine and Science in Sports and Exercise, 32(5), Supplement abstract 916.

Ss (N = 13) ingested one of three solutions on different occasions. The solutions were: 20 mg/kg of water, 20 mg/kg water with 1.5 gm/kg of glycerol, and 20 ml/kg of water with 1.5 gm/kg glycerol and 60 mmol/l of sodium. Exercise (running one hour, broken into three 20-min segments, at 65% VO2max) was started 50 minutes after the last portion of fluid was ingested.

All solutions induced a state of hyperhydration, with the glycerol solutions producing a greater effect, primarily due to the retention of urine. Sweat rates were lower in the glycerol groups and better blood plasma and volumes were maintained. There were no differences in tympanic temperatures, heart rates, or one mile run times.

Glycerol appeared to have a beneficial effect on maintaining fluid. That is important for activities where fluid replenishment is not available.

Implication. Glycerol promotes fluid retention.

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