Nutrition News & Views

June 5, 1999
Sports Drinks - June 1999/No. 2

Sports drinks have invaded the mainstream, showing up on the shelves of every supermarket and health food store. As an athlete and a consumer, you are wondering if sports drinks are necessary and offer any performance benefits. What are sports drinks, who needs them, and how do they work?

Sports drinks vary somewhat in formula, but essentially they contain water, carbohydrates, electrolytes, and vitamins. Most sports drinks contain between 5 - 8 % carbohydrate, or simple sugars. They also supply electrolytes, mainly sodium, chloride, and potassium. These are key for the body's fluid balance and are crucial in preventing muscle cramps. The water helps the cardiovascular system from getting over strained in its attempt to keep the body cool.

Sports drinks are not necessary for all athletes or all activities. They are recommended for aerobic (with oxygen) activities lasting longer than an hour. So if you are involved in running, biking, or other endurance events lasting more than one hour, sports drinks may provide some performance benefits.

The most critical concerns of an endurance athlete are having enough fluids to keep the body cool (maintain core body temperature of 98.6 degrees F), and enough fuel to provide energy. Sports drinks help replace the water lost through sweating, which is the body's cooling mechanism. Water is an important part of an adequate blood supply, which is crucial in keeping the body cool, supplying enough oxygen to the working muscles, and removing heat and waste from these muscles quickly. Besides water, sports drinks also supply carbohydrates, which give energy to the working muscles. If you are periodically consuming sports drinks during activity, you may increase your endurance, postpone fatigue, and improve performance.

Sports drinks also supply electrolytes, which is crucial as your body loses sodium and other electrolytes when you sweat. Not only are the electrolytes replaced, but these electrolytes have important functions in the body. Sodium helps glucose move across the intestinal wall, thus helping the carbohydrates pass through the body and reach the muscles quicker. Sodium also helps make the drink taste better, which leads to greater consumption by the athlete.

Drinks with a lot of sugar take longer to be absorbed, thus this is why it is crucial that these sports drinks have only 5 - 8 % carbohydrate, as compared to soft drinks and fruit juices which are more concentrated at 10 - 15 % carbohydrate. Also, cooler drinks, besides tasting better, also move from the stomach to the intestine faster, thus moving through the body faster, for quicker utilization. These two factors will also help reduce the incidence of cramping and nausea during extended aerobic activity, as the drink will not sit in your stomach for a long time, but rather move quickly to the bloodstream and to the working muscles.

In conclusion, to optimize your performance during extended aerobic activity, you need to take in adequate fuel, fluids, and electrolytes. Sports drinks supply all of these and can help you maintain your endurance, postpone fatigue, and improve performance.

Submitted by Steve Ferguson, MSU Dietetic Intern
Distributed by Barbara McLaurin, PhD., R.D., L.D., Human Nutrition Specialist, MSU Extension Service, June 1999

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