From NutritionforKids.Com – Connie Evers, MS,RD

"Supervision is essential because children do not instinctively drink enough fluid to replace body water losses," says Dr. Steen. And, she cautions, kids in all sports need to replenish their water stores. While swimmers or ice skaters may believe their cool environment keeps them cool enough, muscle work of any kind causes the body to lose water through sweat.

She offers the following guidelines for kids active in sports, exercise, or active play:

Drink 10-14 ounces of cold water 1-2 hours before the activity and another 10 oz. 10-15 minutes before activity. During activity, water breaks should be provided every 15 minutes with the goal of drinking at least 3-4 ounces. Plain, cold water is the best because it is quickly absorbed by the body.

Each child involved in sports and active play should have their own personalized water bottle.

Flavored drinks taken during sports or activity are suitable only if they have a sugar concentration of 6-8% or less, which translates to 15-18 grams of carbohydrate per 8 ounces (check the label). More concentrated drinks slow the absorption of water into the body.

While many sports drinks fit this guideline, fruit juices and other sugar-flavored drinks need to be diluted by mixing with an equal amount of water.

Carbonated soft drinks are not a good choice for playing-field water replacement because the bubbles can cause a stuffy, bubbly feeling in some children. Iced tea and soft drinks which contain caffeine -- a diuretic -- actually cause the body to lose more fluid.

Weigh young athletes before and after practice and games. Each pound lost should be replaced by drinking 16 ounces (2 cups) of fluid.

Remember, as the heat pours on this summer, be sure to "pour in" the fluids. Water is by far the most important nutrient - yes, it is a nutrient - and a deficiency can seriously hamper summer fun and play.