NATA Position Statement: Fluid Replacement of Athletes

Dehydration can affect an athlete's performance in less than an hour of exercise - sooner if the athlete begins the session dehydrated.
Dehydration of just 1-2% of body weight (only 1.5-3 lbs. for a 150 lb. athlete) can negatively influence performance.
Dehydration of greater than 3% of body weight increases an athlete's risk of heat illness (heat cramps, heat exhaustion, heat stroke).

Recognize the basic signs of dehydration:

Athletes benefit in many situations from drinking a sports drink containing carbohydrate.
If exercise lasts more than 45-50 minutes or is intense, a sports drink should be provided during the session.
The carbohydrate concentration in the ideal fluid replacement solution should be in the range of 6-8% (g/100mL).
An ingestion rate of about 1g carbohydrate (CHO)/minute during exercise maintains optimal carbohydrate metabolism. For example: 1L of a 6% carbohydrate (14g CHO/8 oz) sports drink per hour of exercise.
During events when a high rate of fluid intake is necessary to sustain hydration, sports drink with less than 7% carbohydrate should be used to optimize fluid delivery.
Fluids with salt (sodium chloride) are beneficial to increasing thirst and voluntary fluid intake as well as offsetting the amount lost in sweat.
Cool beverages at temperatures of 50 degrees to 59 degrees Farenheit recommended.

Fruit juices, carbohydrate gels, sodas and those sports drinks that have CHO levels greater than 8% are not recommended during exercise as the sole beverage.
8% CHO is a warning sign. Replacing fluids with a beverage that has less than 8% carbohydrate would be optimal to assure the fastest rate of fluid absorption.
Beverages containing caffeine, alcohol and carbonation are discouraged during activity because they can dehydrate the body by stimulating excess urine production, or decrease voluntary fluid intake.

Drink according to a schedule based on individual fluid needs. By the time you become thirsty, you're already dehydrated.
Drink before, during and after practices and games (follow the fluid guidelines listed below to maintain hydration and maximize performance).
Avoid soft drinks and juice during play. The high carbs may cause stomach problems.

Before Exercise

During Exercise

Drink Early - Even minimal dehydration compromises performance.
In general, every 10-20 minutes drink at least 7-10 oz of water or a sports drink. To maintain hydration, remember to drink beyond your thirst. Optimally, drink fluids based on amount of sweat and urine loss.

After Exercise

Within 2 hours drink enough to replace any weight loss from exercise. Drink approximately 20-24 oz of a sports drink per pound of weight loss.

This article has been taken from Casa, D et al. Journal of Athletic Training 35(2):212-224, 2000.