Consider that a loss of as little as 2% of one's body weight due to sweating, can lead to a drop in blood volume. When this occurs, the heart works harder in order to move blood through the bloodstream. Prehydration and rehydration are vital to maintaining cardiovascular health, proper body temperature and muscle function.
The natural choice for hydration is water. It hydrates better than any other liquid, both before and during exercise. Water tends to be less expensive and more available than any other drink. You need to drink 4-6 ounces of water for every 15-20 minutes of exercise. That can add up to a lot of water! Athletes who don't consume electrolytes under these conditions risk overhydration (or hyponatremia). The most likely occurence is found in the longer events (five hours or more) when athletes drink excessive amounts of electrolyte free water, and develop hyponatremia (low blood sodium concentration).
XOOMA - Nutritional Drink Nutritional Drink Facts: What should you choose for improved performance? The natural choice for hydration is water. There's a certain appeal in drinking the nutritional drink that Olympic athletes drink, but it should be just water if you're doing 10 minutes on a treadmill. And because many nutritional drinks contain only small amounts of essential nutrients, consumers should look elsewhere for nutrition. That's what we have food for!
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