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.
Categories of sport drinks
Sports drinks can be split into three major types:
- Isotonic sport drinks contain similar concentrations of salt and sugar as in the human body.
- Hypertonic sport drinks contain a higher concentration of salt and sugar than the human body.
- Hypotonic sport drinks contain a lower concentration of salt and sugar than the human body.
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.
Purpose and effectiveness
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".
The drinks are marketed as soft drinks. In response to the Oxford analysis, a soft drinks industry spokesman claimed "By helping people participating in sport to perform better and to recover more quickly, sports drinks can encourage people to exercise more".
An effect of drinking sports drinks with carbohydrates without prolonged exercise is weight gain. A study presented at the Obesity Society's Obesity 2012 scientific meeting found people in their teens gained 3.5 pounds (1.6Â kg) over two years for every bottle of sports drink consumed per day. The leading author of the study, Alison Field of Harvard Medical School, said she was surprised to find that "Sports drinks have an even stronger relationship than sugared sodas with weight gain".
History
In the 19th and early 20th centuries, athletes occasionally drank beer of low alcohol content replenishing water, minerals and energy in the body. As the water is boiled during the brewing process and thus sterilized, the beer was a safer option than water from an unknown source. However, it is studied that even a low dose of ethanol decreases endurance performance: it inhibits liver glucose output during exercise, and also impairs psychomotor skills such as reaction time, hand-eye coordination and balance.
Examples of sports drinks
Commercially available sports drinks include:
See also
References
