Surprising, as it may seem, the most important part of an athlete's diet isn't what they eat, it is what and how much they drink. Hydration before, during and after exercise is especially important for preadolescent children because they have special fluid needs compared to adults, or even teenagers. As a parent or coach, you are responsible for taking precautions to prevent heat illnesses in exercising children and making sure they drink enough fluids.

One of the most important functions of water is to cool the body. As a child exercises, his muscles generate heat, raising his body temperature. When the body gets hot, it sweats. The evaporating sweat cools the body. If the child does not replace the water lost through sweating by drinking more fluids, the body's water balance will be upset and the body may overheat.

To keep from becoming dehydrated, your child must drink fluids before, during and after exercise. To promote fluid intake in kids, fluids containing salt (i.e. sports drinks) have been shown to increase voluntary drinking by 90% and prevent dehydration compared to drinking plain water. To ensure that your child is drinking enough, you should see that she drinks fluids according to the following schedule:

Before Sports

Drinking fluids prior to exercise appears to reduce or delay the detrimental effects of dehydration.

1 to 2 hours before sports: 4 to 8 ounces of cold water
10 to 15 minutes before sports: 4 to 8 ounces of cold water
A good meal with containing water (e.g. fruits)

During Sports

Every 20 minutes: 5 to 9 ounces of a sports drink, depending on weight (5 for a child weighing 88 pounds, 9 ounces for a child weighing 132 pounds)
Any time a child feels thirsty
Encourage drinking fluids during timeouts and breaks
Encourage drinking from their own fluid container and avoid sharing with others
Encourage the ability to drink whenever they want and not to wait until they are told to take a break
Adjust fluid needs during practice according to the weather, amount of equipment worn, and practice duration and intensity.

After Sports

Post-exercise hydration should aim to correct any fluid lost during the practice.

Within two hours: at least 24 ounces of a sports drink for every pound of weight lost
Replace all fluids lost during exercise plus any lost after exercising (going to the bathroom)
Eat a good meal with foods containing water
Chocolate milk is good recovery drink that encourages recovery and hydration

There are several ways to check a child or teenager's hydration status or a change in hydration status over time. A youth's hydration status before and after a sport practice or game, and how their status changes, are particularly important.

Urine Color: Researchers have found that children as young as 7 can be taught to use urine color to determine hydration status if descriptive words or phrases are used that they are already know:
- Light yellow or relatively clear urine ("lemonade") means the athlete is hydrated.
- Bright yellow urine ("mellow yellow") means that the athlete is slightly to moderately dehydrated
- Brownish urine ("apple juice") means the child or teenage athlete is severely dehydrated.

The best way to evaluate urine color is for the child to urinate into a clear cup of some kind. However, it can still be determined inside the toilet bowl as long as the dilutive effect of the extra water is taken into account.

A helpful way for kids to remember the link between urine color and hydration is for their goal to remind them to "stay in the clear" because a clear or light yellow urine color means they are staying hydrated.

Percentage of weight loss: Weight lost during a practice or game is water the body needs to replace in order to function properly. Determining the weight lost can also aid in replacing fluids after exercise. For every pound of water lost, ½ liter of fluids needs to be consumed. In order to determine percent dehydration simply weigh the youth athlete immediately before practice and immediately after.
- Ideally, a child should only be wearing shorts while on the scale. Shoes, socks, and other articles of clothing that can soak up sweat should be removed.
- To find out the the percentage of dehydration subtract the post-weight weight from the pre-test weight, divide that number by the post-test weight and multiply that number by 100. For example, a 110 pound child who loses 2 pounds during sports is 1.8% dehydrated (110-108/110 x 100= 1.8%).
- 1-2% dehydration can adversely affect performance; percentage losses greater than 3% can have adverse health effects.

Thirst: Studies of children and teenagers have shown that thirst is not a reliable indicator of hydration status. Although the precise reason is unclear, experts speculate that it is likely due to the fact that children and teens playing sports get distracted by the enjoyment of the sport. While a lack of thirst does not necessarily indicate the individual is hydrated, the fact that a child or teenager is thirsty, does indicate that the individual is dehydrated to one degree or another. This means that asking a child if she is thirsty while playing sports is not a good way to measure hydration status, but if the child voluntarily expresses thirst, it can be safely assumed the child is already dehydrated.

A good way to remember these hydration measures is to use a mnemonic": WUT, which means if there is Weight loss, a darker Urine color, and Thirst is present, the child is dehydrated and re-hydration strategies should be followed.

Urine Specific Gravity

Teenagers who participate in organized sports programs that conduct hydration checks may have their urine checked for specific gravity. A small telescope-looking instrument determines the density of the urine as compared to the density of water. The higher the density, or specific gravity, the more dehydrated the sample is. A urine specific gravity of 1.000-1.019 is considered a hydrated youth, 1.020-1.027 is considered a minimal to moderate dehydrated youth, and 1.028-1.035 is considered severely dehydrated

Dehydration symptoms

If a youth is experiencing either (a) an increase in the number of dehydration symptoms they are experiencing, or (b) an increase in the severity of the symptoms, than dehydration is present and possibly also increasing in severity.

Teaching Children About Hydration

Dehydration is preventable

By Gwenn Schurgin O'Keeffe, MD, FAAP

When you are watching your favorite sports team on TV, have you ever noticed that the first thing the athletes do when they get to the sideline or dugout is get a drink? Whether on their own or from the hand of a trainer, they drink constantly every chance they get throughout the game. That is how important hydration is to athletic performance.

So it is a true mystery to me that proper hydration isn't weaved in the fabric of our youth sports culture. In fact, proper hydration is just as important to safety as any protective equipment. If our young athletes had better access to the right fluids in the right way, their sports performance would not only dramatically improve but the risk of one of the most dangerous sports injuries, dehydration and heat illness, would be dramatically reduced.

Thirsty? Think Salt!

You've heard the old saying that the human body needs 8 glasses of water a day to stay healthy. Did you know that was a myth? In fact, it is one of the biggest pop medical myths of our time. No one is quite sure where it came from and no scientist to date has been able to prove that 8 is the number. What we do know is that our bodies need fluids to function, water being one of them, and an important one since 80% of our body is comprised of water. However, to be "water balanced" we need salts (electrolytes), too, especially sodium and potassium, and some sugar, namely glucose.

Typically, we lose water and salt together in tears, sweat, urine and stool. As we go about a typical day with a normal diet that water and salt gets replaced just fine. But sometimes, in special situations, we can lose a bit more of water or salt such as with fever or gastrointestinal illnesses and we need more fluids than we typically need. Sports and warm weather are the two other special circumstances that put people at very high risk for becoming dehydrated and the people at most risk are kids. This is when we need to worry about becoming dehydrated and where rehydration with fluids, including sports drinks, play an important role.

The only other way to replace fluids when dehydrated is by an intravenous line and sometimes that is needed. However, with proper hydration before, during and after a sports workout or game, a child can be spared this simple yet often unsettling procedure.

Many parents don't know that sports drinks are designed as rehydration fluids, not for general use, so they end up not giving them to their children out of fear of all the "extra calories" they supposedly contain. It is true that extra calories might be an issue (and, for some kids, is an issue) if you gave sports drinks to your kids to drink during the day as regular hydration. But used for their intended purpose - to re-hydrate and replaced energy stores used during exercise - the extra sugar in a sports drink simply replaces the sugar your child uses up during exercise.

What Is Dehydration?

Our bodies operate by a simple principle of balance. Our normal diet of food and drink is designed to replace what we typically use up in our bodies as we go about our day. Our hunger and thirst mechanisms help us know when our bodies are low on energy (protein and sugar) or fluids. When we exert ourselves more such as with exercise (or even during illness), our bodies need more energy and fluids because our bodies are working overtime and are using up stores of sugars, salts and fluids.

If we don't replace the fluids, sugars and salts we lose during exercise, our bodies stay depleted of those things and that is when we become dehydrated.

The symptoms of dehydration are relatively "standard" in both adults and kids. There is, however, one major difference: kids and young teens don't sense thirst as well and they don't show signs of dehydration until much later in the dehydration process than older teens or adults. As, a result, by the time a child or young teen is showing signs of dehydration, they are more severely dehydrated than an older child would be with the same symptoms.