Lack Of Fluids Reduces Athletic Performance

Elizabeth S. Reames, Claesgens, Mark A.  |  7/13/2007 2:58:39 AM

2007 Back-to-School News (Distributed 07/12/07)

Athletes need adequate fluids for optimal physical performance. Dehydration impairs performance by causing cramps, weakness and headache. Dehydration can lead to higher core body temperature, which increases strain on the cardiovascular system. Untreated, dehydration can cause heat stroke.

Adequate fluid replacement helps maintain hydration and, therefore, promotes the health and safety of athletes, according to the American College of Sports Medicine. Experts recommend athletes hydrate with fluids before, during and after activity or competition to help regulate body temperature and replace body fluids lost through sweat.

Dehydration of just 1 to 2 percent of body weight (only 1.5-3 pounds) for a 150-pound athlete) can negatively influence performance. Dehydration of greater than 3 percent of body weight increases an athlete’s risk of heat illness (heat cramps, heat exhaustion, heat stroke).

LSU Agricultural Center nutritionist Dr. Beth Reames offers several tips to for proper hydration:

– Drink before, during and after practices and games.

– Drink early; by the time you’re thirsty, you’re already dehydrated.

– Include liquids with the pre-competition meal.

– Drink fluids based on the amount of sweat and urine loss during the activity.

Reames recommends water for most types of exercise of one hour or less under moderate temperature conditions. For intense exercise events lasting longer than one hour, the nutritionist recommends sports drinks or diluted juices containing carbohydrate in concentrations of 4 to 8 percent.

These beverages are also suitable for hydration during exercise events lasting less than one hour. "Since they are flavored, they are often preferred over plain water," Reames said, adding that any of the fluids should be cool, between 59 and 72 degrees F.

The American Dietetic Association suggests the following guidelines for fluid replacement:

– About two hours before exercise or competition, athletes should drink about 2 cups of fluid.

– During exercise, athletes should start drinking early and drink regularly to replace water lost during sweating; that is, 1/2 to 1 cup, fluids every 15 to 20 minutes.

– After exercising, drink at least 2 cups of fluid per pound of body weight lost during exercise. Foods eaten after the event are usually sufficient to replace sodium.

The risks of dehydration and heat injury increase dramatically in hot, humid weather. If athletes compete under these conditions, every precaution should be taken to assure they are well hydrated, have ample access to fluids and are monitored for heat-related illness.

Even when water and sports drinks are available, some kids don’t take advantage of them. Findings from a study presented at a recent American College of Sports Medicine annual meeting, showed that kids at a sports camp were not properly hydrated, even when water and sports drinks were accessible and coaches encouraged routine drink breaks during activity.

According to the report, more than two-thirds of kids participating in a soccer camp were dehydrated early in their participation in the camp. Since dehydration increases medical risk for more serious heat illnesses such as heat exhaustion and heat stroke, the researchers emphasized the importance of adopting a fluid replacement strategy for young athletes engaged in continuous bouts of activity.

Although getting enough fluid is the usual problem of most athletes, participants in extreme athletic events, such as marathons and triathlons, may be at risk for drinking too much fluid, according to the Clinical Journal of Sports Medicine. Overhydrating can lead to a dangerous condition called hyponatremia, or low blood sodium levels. Low blood sodium levels can lead to nausea, fatigue, vomiting, weakness and sleepiness. In severe cases, it can lead to coma and death.

Marathoners who stay out on the course for a long time are at risk for hyponatremia because they lose salt in their sweat. Those who drink lots of fluids in the days before the race and also drink at every drinking station along the course are also at special risk.

For related nutrition topics, click on the Food and Health link on the LSU AgCenter homepage at For local information and educational programs, contact an extension agent in your parish LSU AgCenter office.


On the Internet: LSU AgCenter:
Contact: Beth Reames (225) 578-3929 or
Editor: Mark Claesgens (225) 578-2939 or

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