Calculating Fluid Needs by Susan Paul, MS TSF Training Program Director

Fluid intake is the most important nutrition consideration for any athlete. A loss of body weight of just 1% (1.5 pounds in a 150-pound athlete) can adversely affect the body's ability to cope with the stress of exercise. A loss of more than 1% of body weight can impair athletic performance. Individuals exercising in warm, humid environments must pay special attention to fluid intake. Sports dietitians should help athletes develop a fluid plan to drink before, during, and after exercise.

Key Points About Fluids

  • An athlete must drink to stay hydrated. Pouring fluids over the head does not prevent dehydration.
  • Encourage athletes to practice drinking fluids during training sessions to "train" the body to tolerate fluids during competition.
  • Athletes should plan a schedule in which they drink before they get thirsty. Athletes should not wait until they feel thirsty to drink fluids.
  • Encourage athletes to drink at least 2 cups (16 oz.) of fluids 2 hours before they exercise. Measure the amount of fluid in an athlete's sport bottle and mark it in 1-cup intervals for easy reference.
  • Encourage athletes to drink during exercise; recommend 5 to 10 oz. fluid every 15 to 20 minutes.
  • Every large gulp or swallow equals about 1 ounce of fluid.
  • Sport drinks help replace fluid, carbohydrate, and electrolytes lost in sweat.
  • Increased dietary sodium is warranted in athletes who exercise in hot, humid environments. The athletes who are most susceptible to heat cramps are those who sweat profusely, lose significant sodium and chloride in their sweat, and often have a relatively low dietary salt intake. Advise these athletes to increase their sodium intake by adding salt to their sports drink (1/2 teaspoon salt added to 32 oz. of sport drink provides additional 1,180 mg. sodium).
  • Remind athletes to drink plenty of fluids with meals.
  • Endurance athletes should be careful not to drink too much water before or during a distance event. Hyponatremia (low blood sodium) can be the result of too much fluid. Endurance athletes should follow a fluid plan and choose sport drinks instead of water.

Fluid Recommendations

  • 2-3 hours before exercise drink 16-24 oz. or 2-3 cups of water. Drinking 2-3 hours before exercise allows enough time for fluid to be lost through urine before exercise begins.
  • 30 minutes before exercise drink 5-10 oz. or  - 1 cup of water. There is no benefit to taking in more fluid than this at this time.
  • During exercise drink 5-10 oz. or  - 1 cup of water every 15 minutes. One gulp equals about 1 oz.
  • After exercise drink at least 20 oz. (2  cups) for every pound lost during exercise. Encourage athletes to weigh themselves before and after exercise for an estimate of water loss.

Sport Drinks with 6% to 8% Carbohydrate

  • Accelerade - available at Track Shack
  • Gatorade - available at Track Shack
  • Powerade
  • Allsport Body Quencher
  • Endura

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