Sport Drinks Promise a Lot, But Do They Deliver?
~ January 2004 No.176 ~
For many people, physical activity is an important part of a healthy lifestyle. For some, the commitment to get more exercise only involves buying a new pair of running shoes. However, many soon become more serious; they invest more time and money into their activity/sport and are, after a while, looking for ways to improve on their performance. It is no surprise that the food industry has responded to this trend and are selling sports drinks that promise a performance that is stronger, faster or higher.
The main benefit of sports drinks is the fact that they provide water during exercise. It is important to replenish water lost through perspiration. Dehydration can affect performance in some cases. In the extreme, dehydration can be an important health risk and may become life threatening if it becomes prolonged. Under normal conditions we should drink a minimum of one litre of liquid a day. Under conditions of high physical activity and or high heat and humidity, the requirement can be as high as 8 litres per day.
Many sports drinks contain different sources of carbohydrates or sugars, and salts, or electrolytes. During exercise, muscles can use the carbohydrates as a source of energy, and the extra intake of carbohydrate can help maintain blood glucose levels. The electrolytes can also regulate the thirst mechanism, replace slats lost in perspiration and reduce the risk of dehydration.
Today sports drinks may also contain a wide variety of vitamins, amino acids and other primary and secondary nutrients. However, currently there is little evidence - either metabolic or performance parameters - to support the addition of these ingredients to sports drinks.
The most important question asked by consumers of sports drinks is whether drinking sports drinks can improve endurance or performance. At this time the best answer is “maybe”. There has been data published to show that endurance trained athletes improved their performance by drinking a carbohydrate-electrolyte solution before and during a one hour cycling trial, compared to a placebo. However, a second study with trained cyclists was not able to show any improvement in performance over placebo when the subjects consumed a carbohydrate-electrolyte solution before a 20 km bicycle trial.
Carbohydrate-Electrolyte Feedings Improve 1 h Time Trial Cycling Performance
Int J Sports Med 1997,18:125-129