Sports drinks

Sports drinks are beverages whose stated purpose is to help athletes replace water, electrolytes, and energy before and after training or competition, though their efficacy for that purpose has been questioned, particularly after exercise.

Sports drinks can be split into three major types:

Most sports drinks are approximately isotonic, having between 4 and 5 heaped teaspoons of sugar per five ounce (13 and 19 grams per 250ml) serving.

Athletes actively training and competing lose water and electrolytes by sweating, and expending energy. However, Robert Robergs, an exercise physiologist at the University of New Mexico who studied Gatorade, said that unless someone is exercising or competing in a sporting event for longer than 90 minutes, there is no reason to drink something with excess sugar and electrolytes. The Australian Institute of Sport states that excessive salt supplementation during exercise may lead to "gastrointestinal problems or cause further impairment of fluid balance" and may cause salt-induced cramps.

Sodium in drinks might help to avoid hyponatraemia (low sodium), but only after sustaining athletic activity for more than four hours; a sports drink containing sodium may be appropriate for recovery from intense and prolonged training or competition.

A stated purpose of sports drinks, which provide many calories of energy from sugars, is to improve performance and endurance. In an analysis by Matthew Thompson and colleagues from the Oxford Centre for Evidence Based Medicine, of 431 marketing claims of performance enhancement, most cited no evidence. 174 sources were cited for GlaxoSmithKline's Lucozade; of them, Thompson found only three studies of high quality with a low risk of bias. The rigorous studies that did show improved endurance were "of limited relevance to most people because the tests were on elite athletes". Thompson said that, for the vast majority of people, drinking such products "could completely counteract exercising more, playing football more, going to the gym more".

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