Volterman, K., Obeid, J., Wilk, B., & Timmons, B. W. (2012). Effect of milk intake on electrolyte balance in children after exercise in the heat. Presentation 2293 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

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This study evaluated the hypothesis that due to higher electrolyte content, milk will be more effective than both water and a carbohydrate/electrolyte solution in replacing electrolyte losses in children (8-10 years; M = 6; F = 8) following exercise in the heat (35șC, 50% relative humidity). Ss performed three trials in a warm environment consisting of two 20-minute cycling bouts at 60% VO2peak followed by consumption of water, carbohydrate/electrolyte solution, or skim milk. Each beverage was consumed in a volume equal to 100% of their body weight losses and began immediately after exercise. Urine samples were collected before, during, and after exercise, as well as during the 120 minutes following drink consumption.

Ss ingested 399 ± 97 mL of fluid. Children remained in a net negative balance for Na+ and Cl- at the end of the 120-minute recovery for all beverages. No difference was found between beverages for Na+ balance; however, children maintained a more positive Cl- level following the consumption of skim milk compared to the water and the carbohydrate/electrolyte solution conditions. Similarly, K+ balance was significantly greater in the skim-milk trial compared with both the water and carbohydrate/electrolyte solution trials; with no significant difference between the water and carbohydrate/electrolyte solution trials. Children were able to return to a net positive K+ balance following the consumption of skim milk, whereas they remained in a net negative K+ balance during the carbohydrate/electrolyte solution and water trials.

Implication. Skim milk ingestion was effective at maintaining a more positive electrolyte balance for both K+ and Cl- when compared to water or carbohydrate/electrolyte consumption when recovering in the heat.

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