The following article is found at http://www.ianr.unl.edu/pubs/foods/nf72.htm

Nebraska Cooperative Extension NF92-72 (Revised May 1998)

Nutrition and the Athlete
Fluid Replacements

Linda Boeckner, Extension Nutrition Specialist, University of Nebraska Panhandle Research and Extension Center

A fluid loss of as little as 2-3 percent of body weight impairs performance. Fluid losses of 7-10 percent of body weight will lead to heat stroke and death. For a 150-pound person, a 2-3 percent fluid loss equates to 3 to 4 1/2 pounds of body weight.

Research shows that endurance athletes who are involved in physical activity for more than an hour and a half can produce up to three quarts of sweat per hour. That equals a loss of 6 pounds of body weight.

Five Basic Rules for Fluid Replacement

1.      Cool fluids are best (40 - 50o F).

  1. Plain water, or sports drinks and diluted juices that have 4-8 percent carbohydrate concentration, adequately replace fluid for most athletes. On sports drink labels look for carbohydrate contents of less than 20 grams per 1 cup (8 oz). Dilute fruit juice by mixing one part juice with one part water. Extremely concentrated beverages such as carbonated sodas, undiluted fruit drinks and juices, and high carbohydrate supplements will slow absorption rates. They are not useful for immediate fluid replacement.
  2. Don't depend on thirst. By the time you feel thirsty, your body already has started to dehydrate.
  3. Weigh before and after an athletic event. Replace 2 cups fluid for every 1 pound lost.
  4. Sip water or dilute fluids (<20 grams of carbohydrate per cup) during competition or training. Athletes involved in steady competition or training for longer than one hour may benefit by using cool, pleasantly flavored, lightly sweetened beverages such as diluted fruit juices or sports drinks. These beverages provide both a fluid replacement and carbohydrates.

The suggested protocol for fluid replacement is:

Drink 2 cups cool water about 2 hours before competition or training. Follow this by drinking 1 to 2 cups fluid 15 minutes before the event.

Drink 4 to 6 oz (1/2 to 3/4 cup) of cool water, diluted fruit juice or sport drink every 10 to 15 minutes during competition or workout.

After competition or workout, weigh and replace every pound of lost weight with 2 cups plain water or sweet-tasting beverage. Avoid caffeine-containing beverages and alcohol.

Resources

Benardot, D. Sports Nutrition: A Guide for the Professional Working With Active People. Chicago, IL: American Dietetic Association. 1993. pp 38-44.

Berning, J.R. and Steen, S.N. Sports Nutrition for the 90s: The Health Professional's Handbook. Gaithersburg, MD: Aspen Publishers. 1991. pp 175-196.

Coleman, E. Sports drink research. Food Tech. 45 (March):104-106, 1991.

Convertino, V.A., Armstrong, L.E., Coyle, E.F., Mack, G.W., Sawka, M.N., Senay, L.C. and Sherman, W.M. American College of Medicine position stand on exercise and fluid replacement. Med. Sci.Sports Exerc. 28 (1):i-vii, 1996.

Davis, J.M., Burgess, W.A., Slentz, C.A. and Bartoli, W.P. Fluid availability of sports drinks differing in carbohydrate type and concentration. Am. J. Clin. Nutr. 51:1054-1057, 1990.

Hoffman, C.J. and Coleman, E. An eating plan and update on recommended dietary practices for the endurance athlete. J. Am. Diet. Assoc. 91:325-330, 1991.

Houmard, J.A., Egan, P.C., Johns, R.A., Neufer, P.D., Chenier, T.C. and Israel, R.G. Gastric emptying during 1 hour of cycling and running at 75% VO2max. Med. and Sci. in Sports and Exer. 23:320-325, 1991.

Steen, S.N. Timely statement of The American Dietetic Association: Nutrition guidance for adolescent athletes in organized sports. 1996. The American Dietetic Association Web Page. Retrieved June 26, 1997.
 

File NF72 under FOODS AND NUTRITION
C-3d, Special Diets
Revised May 1998

Electronic version issued June 1998
pubs@unl.edu

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kenneth R. Bolen, Director of Cooperative Extension, University of Nebraska, Institute of Agriculture and Natural Resources.

University of Nebraska Cooperative Extension educational programs abide with the non-discrimination policies of the University of Nebraska-Lincoln and the United States Department of Agriculture.