An eighteen year old who is not vigorously exercising needs approximately 2.5 quarts of replacement water every day. This is needed to replace water excreted via urine (1.3 quarts), the skin (0.85 quart by perspiration), and the lungs (0.35 quarts by exhaled air). To replace this water, the average individual consumes a minimum of 1.2 quarts (38 ounces or five glasses) of fluid each day, and an additional 1.0 quarts in foods, such as fruits and vegetables, which contain large amounts of water. In addition, 0.3 quarts of water is formed when food molecules are degraded for energy. With vigorous exercise, there will be an increase in the loss of fluid from the skin (from up to 3.0 to 5.0 quarts) and from the lungs (up to 0.7 quarts). This increased loss of water will make the player dehydrated unless replaced; the athlete needs to drink several quarts of water to prevent dehydration.

Plain water, preferably cold, is the best fluid replacement. Cold water leaves the stomach faster than warm water, and will decrease bloating. Plain water leaves the stomach much faster than drinks containing glucose (sugar), such as Coca Cola, Pepsi, Gatorade or Exceed. The purpose of hydration in sports is to get water to the working muscles and cells as soon as possible.

During exercise lasting less than ninety minutes, there is no evidence that a carbohydrate-electrolyte drink (such as Gatorade) is any better than plain water.
In addition to the fact that sugared drinks leave the stomach slower than plain water, players should avoid highly sugared drinks (greater than 5% glucose) and chocolate bars within one hour of a game or practice for another reason. This sugar load will cause the body to secrete a hormone (insulin) that will actually cause a decrease in the blood level of carbohydrate about thirty to forty minutes after the ingestion of the sugar. This decrease in the blood level of carbohydrate can cause the players to experience a sluggish feeling when they step out on the playing field or ice surface.

Drinking water before a game or practice, even cold water, will not cause cramps. In fact, there is a good possibility that cramps can result from dehydration due to drinking to little water.
The American College of Sports Medicine recommends drinking about two glasses (17 ounces) of fluid two hours before the scheduled game or practice. During exercise, athletes should start drinking early and at regular intervals in an attempt to consume fluids at a rate sufficient to replace the water lost through sweating and exhaled air. In a practice this could be two to four ounces (a half glass) of water every five to ten minutes.

REFERENCES:

Nancy Clarke's Sports Nutrition Guidebook: Eating to Fuel your Active Lifestyle by Nancy Clark (see Chapter 10 Fluid Facts for Thirsty Athletes)
Champaign, IL, Leisure Press, 1990

Exercise Physiology; Energy, Nutrition, and Human Performance (Fourth Edition) by William D. McArdle, Frank I. Katch, and Victor L. Katch
Baltimore, MD, William & Wilkins, 1991

Hockey Fitness: Year-Round Conditioning On and Off the Ice
by Don MacAdam and Gail Reynolds,
Champaign, IL, Leisure Press 1988

Keeping Young Athletes Healthy: What Every Parent and Volunteer Coach Should Know by Alan R. Figelman and Patrick Young
New York, Simon & Schuster, 1991

Injury Prevention through Fluid Replacement: by Jeffrey Klein Article in Chalk Talk, A Monthly Newsletter for Hockey Coaches, October 1996
1036 Washington, Dearborn, MI 48124 (313) 730-1110

Exercise and Fluid Replacement
American College of Sports Medicine
Position Stand on Exercise and Fluid Replacement
in Med. Sci. Sports Exercise., 28:1, 1995, pp 1-7.