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Nutrition and the
Athlete
Fluid Replacement
- By Linda Boeckner, Extension
Nutrition Specialist,
- University of Nebraska Panhandle
Research and Extension Center
Of all nutritional concerns for athletes
the most critical is proper fluid hydration. One of the key functions of fluid
for the athlete is for body temperature control. Lack of this element above all
others can hinder performance and lead to more serious complications.
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.
Fluid replacement is a special concern for
children involved in sports activities. Children have lower sweating capacity
and they tolerate temperature extremes less efficiently than adults. Young
children also produce more heat during exercise. They typically take two to
three days longer to get used to exercise during warm weather. Keep the water
bottle handy during all sports activities for children. Even better, don't let
your children leave home without it.
Five Basic Rules for Fluid
Replacement
- Cool fluids are best (40 - 50o
F).
- 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.
- Don't depend on thirst. By the
time you feel thirsty, your body already has started to dehydrate.
- Weigh before and after an athletic
event. Replace 2 cups fluid for every 1 pound lost.
- 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.
| Table
I. Composition of selected commercial sport drinks. |
Product
(8 oz) |
Carbohydrate
concentration |
Energy |
Sodium |
Potassium |
| |
% |
kcal |
mg |
mg |
| Bodyfuel 450®a |
4.2 |
40 |
80 |
20 |
| Exceed Fluid Replacement®b |
7.2 |
70 |
50 |
45 |
| Gatorade®c |
6.0 |
50 |
110 |
25 |
| Sqwincher®d |
6.8 |
60 |
60 |
36 |
|
| aVitex
Foods, Los Angeles, CA. |
| bRoss
Laboratories, Columbus, OH. |
| cQuaker
Oats Co, Chicago IL. |
| dUniversal
Marketing Corp, Columbus, MO. |
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.
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