Many athletes do not drink enough to offset the effects of dehydration during competition, even when given unlimited access to fluid (Noakes, 1993). Any strategy that helps the athlete to take on extra fluid or "hyperhydrate" is therefore likely to enhance performance.
The main determining factor whether or not a sports drink would be beneficial to an athlete is the amount of perspiration produced during activity. When you sweat not only does the body loose water, but also electrolytes (salts, such as sodium). When you perspire, your body loses about 900 to 1400 milligrams of sodium per litre of sweat (Shirreffs & Maughan, 2000). These electrolytes cannot be replenished by normal water. Carbohydrates, that can be ingested in the form of sugars, are another important source of energy in the body that water does not contain. In general, adding more sugar to a beverage increases the delivery of sugar to the blood (Moodley, 1992). During exercise, they should consume 30 to 60 grams of carbohydrates an hour. Because eating solid foods can be difficult while exercising, athletes can drink 600 to 1,200 millilitres of sports drinks an hour (Burke, 1993). One thousand millilitres is a little more than a quart. Studies have shown that when participating in activities of less then 90 minutes, or 60 minutes if the activity is intense, then water is an adequate way to maintain the body's internal functions and therefore maintain an adequate level of performance. If an individual exercises for longer than these time limits then a sports drink is considered to be the more effective beverage (Dunford, 2002). In tests done in extreme heat it was found that sports drinks were also very effective in reducing the chance of hypohydration due to an increase in voluntary fluid intakes (Johnson, Nelson & Consolazio, 1988). It is shown that you only get about 60% re-hydrated by drinking water when dehydrated, but you get as much as 80% re-hydrated by drinking various sports drinks (Davis, 1990).
