Henkin, S. D., Silveira, M. M., Lannerhirt, H., Meyer, F., & Kruel, L. F. (2005). Body fluid balance of competitive male swimmers during a training session. Medicine and Science in Sports and Exercise, 37(5), Supplement abstract 549.

This study examined the effects of training and sport drink intake on hematocrit, urine specific gravity, and voluntary drinking in trained adolescent male swimmers (N = 8). Beverages were water for one session and a flavored sports drink in the second. Fluid ingestion was ad libitum.

Less flavored fluid was needed to keep urinary and blood measures within euhydrated bounds than pure water alone. Rehydrating with water alone produced a slightly higher urine specific gravity. Swimmers lost significant body weight in each condition.

Implication. Water or commercial fluid replacement ad libitum is sufficient to maintain body fluid balance during a competitive swimming training session.

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