Since many people participate in sports and athletics, the question of how much fluid should be drunk and what type of fluid is the best is often raised.

How can you determine the proper amount of fluids to drink?During intense prolonged exercise, some people can lose up to six to eight pounds of sweat per hour. The best way of tracking water loss is to keep a daily record of body weight. If a person experiences a weight loss of 1 percent to 3 percent from the previous day's activity, extra fluids are essential. For every pound lost, the person should drink two cups (16 ounces) of fluid.

However, scales for weighing often aren't available. Therefore, fluid loss can also be assessed by the amount and color of urine. An adult should urinate about 1.2 quarts every 24 hours. Therefore, infrequent urination can be an indication of fluid need. If urine amount is less than one quart a day, the person needs to drink more fluid. Urine that is dark in color or strong in odor also indicates that the person may be dehydrated.

Everyone should drink at least eight 8-ounce glasses of water a day. Those who sweat heavily should drink two cups (16 ounces) of fluid before exercise followed by another two cups 15 to 20 minutes after exercise and four to six ounces of fluid every 15 minutes during exercise.

Do athletes need to replace sodium and potassium lost through sweat?

Many are concerned about sodium and potassium (electrolytes) that may be lost through sweating and ask if they need to be replaced. Sodium is the mineral most affected by physical exercise. Under extreme conditions, those who sweat profusely, who are not acclimated to the heat, or who have low sodium intakes may experience heat cramps or exhaustion due to sodium imbalance.

An adequate consumption of salt is rarely a problem in the typical American diet. In fact, most Americans consume an excessive amount of sodium, averaging five to 10 grams of sodium per day, although we probably require only one to three grams. Sodium is widely used as a flavoring agent and a preservative in packaged foods, and most Americans use table salt on food. One "Big Mac" supplies the sodium needs for one day.

Should an electrolyte solution be used?

Some sport drinks are promoted as sources of sodium, potassium and sugar especially for those who have lost them through exercise and physical activity. However, the best way to meet sodium needs is by eating a diet that includes a variety of foods. Sodium is found naturally in many of the foods and beverages we eat and drink. In fact, many experts believe that the typical American diet is too heavily laden with sodium. Some athletes also may need to increase their intake of foods higher in sodium (e.g., pizza, ham, salted snack foods) or put salt on foods during meals.

What is the best fluid replacement beverage? For most people who exercise for one hour or less in moderate temperatures, cool water is the best choice. During endurance exercise (events lasting longer than 60 minutes of continuous effort), the best fluid replacement beverage is one that tastes good, does not cause stomach upset and provides a source of carbohydrate for energy.

Is one sport drink better than another?

Studies show that commercial sport drinks containing 6 percent to 8 percent carbohydrate in the form of glucose polymers, or sucrose, are absorbed quickly and help maintain blood glucose levels during exercise. Beverages containing fructose leave the stomach more slowly and, if levels are high enough, may cause cramps, diarrhea and nausea in some people.