Replenish fluids your body loses during exercise

May 13, 1997|By Lynn F. Little

Replenish fluids your body loses during exercise

People of all ages can improve their health by including moderate amounts of endurance-based physical activity in their daily lives. Physical activity has been shown to reduce the risk of premature death in general and of coronary heart disease, high blood pressure, colon cancer and diabetes, in particular. Regular participation in physical activity also appears to reduce depression and anxiety, improve mood, increase feelings of well-being and to enhance one's ability to perform routine tasks.

When you exercise, you need to replenish the fluids your body loses from sweating. If you are a real go-getter, that could be a problem. If you weigh about 150 pounds and sweat away more than 2 percent of your body weight, or three pounds, you are putting your heart under stress.

When the body is under stress, your temperature increases and performance declines. During continuous, high-intensity exercise in hot weather, you can sweat away two to four pounds (one to two quarts) in an hour. Fluid replacement is critical. Dehydration severely limits performance. Heat stroke, organ damage and possible death may result if fluids are not consumed at regular intervals during exercise.


The best way to avoid dehydration is to drink enough fluids to offset fluid loss. Drink before, during and after a workout. Thirst is not an adequate indicator of dehydration. By the time you feel thirsty, you may be dehydrated. You can quench your thirst before the body's fluid replacement requirements are met. Sport physiologists recommend that you start drinking before you feel thirsty and keep drinking a diluted sports drink.

Sodium's role

Replenishing the body's electrolytes, which is a major selling point of sports drinks, is less important than the ads would have you believe. It is true that sodium, which helps regulate the body's fluid balance and plays a role in muscle contraction, is lost in sweat. Except for athletes who compete in endurance events, exercisers don't need to worry about running short on sodium or potassium. Both of these nutrients are plentiful in the American diet.

Here are some tips to keep from "running dry."

- Drink water before exercise. Drink water, diluted fruit juice or a diluted sports drink during exercise, practice and competition.

- During exercise, drink about eight ounces of fluid every 15 to 20 minutes. Cool drinks are absorbed more rapidly.

- If you exercise vigorously for less than one hour or moderately for less than two hours, water is all you need. Add a squeeze of lemon or lime and/or a splash of juice for variety.

- If you exercise strenuously for more than one hour or moderately for more than two hours, you can benefit from an energy drink. Be sure the carbohydrate content doesn't exceed 8 percent by weight. More than that will slow absorption and may cause stomach cramps. Also, if you are exercising in order to help lose or maintain weight, be aware that sports drinks chalk up a fair amount of calories, most in the form of sugar, but generally provide little else in the way of nutrients.

- Refuel your muscles within two hours after exercise.

- Avoid drinks with caffeine or alcohol which are thought to have a dehydrating effect. Carbonated drinks tend to make you feel full, making it difficult to drink enough fluid.

- Always make fluids a part of your exercise routine, never restrict fluids during exercise. It is best to drink small amounts of water at frequent intervals while you are exercising. This will help prevent the uncomfortable feeling of becoming bloated or water-logged.

Regular physical activity can help improve your stamina an strength as well as your psychological well-being by increasing your ability to perform routine tasks. Choose physical activities that you enjoy doing because you're likely to stick with them and be sure to drink plenty of water as you exercise!

Maryland Cooperative Extension Service's programs are open to all citizens without regard to race, color, sex, disability, age, religion or national origin.

Lynn F. Little is an extension agent, home economics, Cooperative Extension Service, University of Maryland.

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