ISOTONIC DRINK

Isotonic sports drinks contain proportions of water and other nutrients similar to the human body, and typically are six to eight percent sugar.

It is a beverage designed to help athletes rehydrate, as well as replenish electrolytes, carbohydrates, and other nutrients, which can be depleted after training or competition. Electrolyte replacement promotes proper rehydration, which is important in delaying the onset of fatigue during exercise. As the primary fuel utilized by exercising muscle, carbohydrates are important in maintaining exercise and sport performance.

Most sports drinks are moderately hypertonic, having between 13 and 19 grams sugar per an eight ounce serving. They also commonly have a pH comparable to carbonated soft drinks.

Risk of Water Intoxication
Consumption of excessive amounts of water can cause water intoxication, a potentially fatal imbalance of electrolytes in the body. Water intoxication is extremely rare. It might occur, for example, during intense exercise when heavy sweating removes water and electrolytes from the body, but only large quantities of water are consumed to replace what has been lost. The resulting low concentration of electrolytes adversely affect central nervous system function.

Many sports drinks reduce the risk of water intoxication by replenishing fluids and electrolytes in a ratio similar to that normally found in the human body. However, some sports drinks have low concentrations of electrolytes, so zealous overconsumption of them could also lead to water intoxication.[4] People whose work or exercise puts them at high risk of developing heat illness or water intoxication should seek professional advice about proper rehydration.


http://en.wikipedia.org/wiki/Sports_drink