National Athletic Trainers' Association Position Statement: Fluid Replacement for Athletes -- 05/15/2007

REACH FOR A GLASS OF MILK AFTER YOUR NEXT WORKOUT

New study suggests lowfat milk may offer a post-exercise hydration advantage

Thinking of grabbing a sports drink after your next workout? You may want to think again and try a glass of milk, suggests a new study published in the British Journal of Nutrition. [1] Researchers found that lowfat milk may help keep you hydrated after exercise better than a commonly used sports drink or water.

To test the post-exercise hydration of 11 healthy men and women, researchers gave participants one of four beverages (water, a commercially available sports drink, lowfat milk or lowfat milk with added sodium) twenty minutes after an exercise session. Since exercise typically results in mild dehydration, the scientists evaluated the hydration status of each subject in a randomized, crossover design hourly for four hours following each of the beverages to see how each affected hydration status.

The researchers found that subjects remained hydrated throughout the recovery period only after drinking the milk beverages. When offered water or the sports drink, the participants returned to a mildly dehydrated state one hour after drinking the beverage. Measuring urine output to further determine hydration, researchers found greater fluid losses after the water and sports drink. Average urine outputs were 611ml and 550ml after drinking milk and milk with added sodium compared to 1184ml and 1205ml after the water and sports drink.

According to the National Athletic Trainers’ Association, “postexercise hydration should aim to correct any fluid loss accumulated during the practice or event,” and maintaining hydration is key for health and physical function. [2]  According to the Association, rehydration beverages should include water, carbohydrates and electrolytes – a nutrition profile that closely matches lowfat milk.

The researchers suggest that it’s this nutrition profile, specifically the naturally-occurring electrolytes like sodium and potassium, that makes milk useful for maintaining fluid balance. Lowfat milk also contains protein and some fat so it may empty from the stomach at a slower rate compared to water and sports drinks, which would also help exercisers retain fluids.

Whether as a post-exercise hydration beverage or a lunchtime beverage, milk provides nine essential nutrients, including calcium, protein, potassium, and vitamins A and D. The Dietary Guidelines for Americans recommend consuming three servings of lowfat or fat-free milk each day. For more information about the health benefits of milk, visit www.thinkaboutyourdrink.com.

[1] Shirreffs SM. Watson P. Maughan RJ. Milk as an effective post-exercise rehydration drink. British Journal of Nutrition; 2007:1-8.

[2] Casa DJ, Armstrong LE, Hillman SK, Montain SJ, Reiff RV, Rich BS, Roberts WO, Stone JA. National Athletic Trainers' Association Position Statement: Fluid Replacement for Athletes. Journal of Athletic Training. 2000;35:212-224.


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