As you strive to ensure that your kids -- and you -- get enough exercise, don't forget to add water. A study presented to the American College of Sports Medicine shows that many children in summer sports camps are dehydrated, despite the availability of water and sports drinks and encouragement to drink them. The study did not examine adult hydration habits, but experts' advice on drinking enough fluids before and during exercise applies equally to kids and adults.

The study of 34 boys and 24 girls aged 10 to 14 enrolled in four-day soccer camps found that most of the children were dehydrated by the second day of camp and that 59 percent of boys and 70 percent of girls were significantly dehydrated by the last day of camp.

Study author Douglas Casa, director of athletic training education at the University of Connecticut and a member of Gatorade's board of advisors, said there is no easy way to say exactly how much each child should drink to be adequately hydrated.

"The key message is that you don't want to lose weight [from fluid loss] during exercise, so whatever you sweat out must be replaced," Casa said. The best strategy, for both kids and adults: Drink 20 to 30 extra ounces of water or a sports drink at least 30 minutes before you start exercising and, if you will be exercising for more than an hour, drink more fluids during your workout.

He and other fitness experts advise against drinking soda or juice just before or during exercise. Sugary drinks like these, they say, sit in your stomach longer and can contribute to cramping.

Casa said he was alarmed that the children in his study ignored the available drinks and coaches' encouragement to drink. "What struck me was that they focused more on socializing during their breaks and that they did not understand that the sweat leaving their bodies during exercise needs to be replaced."

Dehydration spirits vital sodium out of the body and can lead to heat exhaustion and heat stroke. In extreme cases, bodily functions can shut down, causing death. Signs of dehydration include headache, extreme thirst, nausea, weakness, a drop in athletic performance and dark-colored urine.

"If your urine is the color of lemonade, you're adequately hydrated," Casa notes. Casa recommends sports drinks over water for kids' hydration because they are likely to drink more of them. He says all brands of sports drinks offer similar benefits -- replacing fluid and sodium, without adding a lot of sugar.

Over-hydration (hyponatremia, or low sodium content in the blood) is highly unlikely unless you are pushing yourself to your physical limit -- for example, in a major endurance event like a marathon. To avoid hyponatremia, replace fluids during exercise only as you begin to feel thirsty, not before. Drink small amounts as needed throughout your workout. Sodium-laden sports drinks are a better prevention than water, but water is a key component of daily hydration.

Grab a drink and join us for the Moving Crew online chat, this Thursday at 11 a.m. at www.washingtonpost.com/wp-dyn/liveonline/health/movingcrew. We'll be joined by swimming expert Donnie Shaw, director of aquatics at the National Capital YMCA.

-- John Briley