From Sally S. Harris, M.D., MPH

What is the best way to prevent dehydration? Should my child drink a sports drink? Does my child need extra salt?

In most situations, water is an adequate fluid to prevent dehydration. It should be readily available during exercise. Sports drinks, which usually contain 6-8% carbohydrate, are beneficial only for exercise activities lasting longer than 90 minutes. However, children may drink a flavored drink if they prefer the taste. Children should be encouraged to drink before they feel thirsty, because mild dehydration occurs before one feels thirsty. Approximately one cup of fluid is required for every 15 to 20 minutes of strenuous exercise to prevent dehydration. Young athletes should understand that even mild dehydration impairs performance and leads to fatigue. Salt tablets should be avoided; they can cause dangerous side effects and are unnecessary, because salt loss is adequately replaced through a normal diet.