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Defeating dehydration

Defeating dehydration


Too much sweating and low fluid intake can put young athletes at risk for dehydration. Use the tips and information below to help children stay hydrated, safe and in the game.

By Jill Castle, MS, RDN

On a hot summer day, you will find many young athletes outside, practicing and playing sports. Baseball players stand out in the hot sun, track athletes are training and soccer players hit the field on humid days.

What do they all have in common? They are all at risk for dehydration.

Sarah, a teenage track athlete, became dehydrated during the weeks leading up to a track meet. She thought she had been drinking enough, but in fact she had been meeting her minimum requirements, and over time had accumulated a negative fluid balance. On race day she collapsed on the track due to dehydration. She was carted off to the hospital for intravenous fluids.

Up to 75 percent of young athletes aged eight to 18 come to practice already dehydrated, according to researcher Dr. Susan Yeargin from the University of South Carolina. The main culprits of dehydration are too much sweating and low fluid intake, but other factors contribute to dehydration, especially in the youth athlete.

The effects of dehydration

Athletes see significant decline in their athletic performance from dehydration. Dehydrated muscles are not able to react and contract as quickly and efficiently as a well-hydrated muscle. Dehydrated muscles can also get stuck in a contracted state, otherwise known as a cramp. Additionally, the brain may become confused and decision-making more difficult. The heart has to work more to pump blood throughout the body, causing an increased pulse and faster breathing.

In children, one percent dehydration, equivalent to a half- to one-pound weight loss in a 100 pound athlete, can impair athletic performance by cutting down endurance. In teens, a two percent dehydration (a two pound weight loss after exercise in a 100 pound athlete) may cause decreased endurance and impair alertness and cognitive function.

Understanding voluntary dehydration

A condition where kids are not thirsty anymore because they have been drinking, but they haven’t consumed enough to cover their hydration needs. Children are at the highest risk for voluntary dehydration, as well as those who have been exercising in hot, humid climates.

The science behind sweating

Sweating is the body’s way of cooling itself, releasing heat that builds up with exercise. If you couldn’t cool yourself, you would cook your internal organs! In addition to letting off heat, the body also loses sodium, chloride and potassium in sweat. Every person sweats differently. Some lose lots of fluid (dripping sweat) while others may hardly break a sweat. Children, in general, sweat less than adults, but once puberty hits, sweating becomes similar. Sweating is good, but you need to make sure to replace the fluid and electrolytes that are lost.

Strategies for staying hydrated

Staying hydrated is a constant effort for any athlete, but being young has its own set of challenges. Developmentally, children and teens need reminders to drink fluids, as they get distracted. They also may not drink enough due to logistics of practice (inadequate breaks for drinking, for example). Young athletes do best when they have a master plan for drinking around exercise and are checking for signs of dehydration.

The experts and the science point to the importance of drinking fluids during practice, especially if muscles are to perform their best and the body can endure the demands of a long, hot practice. The American Academy of Pediatrics (AAP) set guidelines for fluid consumption during exercise for youth as follows:

  1. Children should have appropriate fluid replacement available.
  2. They should consume fluids at intervals before, during and after exercise.
  3. Nine to 12-year-old children should replenish with 3 to 8 ounces of fluid every 20 minutes, and adolescents may consume 32 to 48 ounces of fluid every hour.

Dr. Thomas Rowland, a cardiologist and youth sports researcher at Baystate Medical Center in Massachusetts, has outlined specific hydration parameters for youth athletes:

To prevent dehydration: Child athletes should drink 6 milliliters (ml) per pound of body weight per hour (a 100 pound young swimmer needs 600 ml or 20 ounces per hour). Drink this amount 2-3 hours before and during exercise.

To replenish fluids after exercise: Young athletes should drink 2 ml per pound of body weight per hour (a 100 pound child swimmer needs 200 ml per hour or approximately 7 ounces, per hour). Drink this amount 1-2 hours after exercise, as it promotes adequate hydration status for the next exercise session.

What should young athletes drink?

There are many options for fluid available to the young athlete. The following is a summary with important considerations:

Water: For one-hour sessions of exercise or less, young athletes can drink and stay hydrated with plain water.

Sports drinks: When exercise sessions last more than an hour, young athletes should replace the primary sweat nutrients, sodium and chloride, as well as consume some carbohydrate to improve endurance and keep muscles fueled. This can be accomplished with a sports drink.

Most sports drinks provide a blend of sugars, maximizing the carbohydrate uptake in the muscle. In general, sports drinks come in concentrations of 4 to 9 percent solution (or 14 to 19 grams per 8 ounce serving size). There has been research in young athletes showing that sports drinks containing 8 percent carbohydrate may cause gastrointestinal upset, so lower concentrations may be better tolerated.

Other beverages: Fitness waters and enhanced waters don’t provide enough carbohydrate for a long workout, but could be fine for shorter exercise bouts (less than an hour). Soda and other sugary beverages such as juice drinks, sweet tea, or lemonade are to be avoided as they may cause stomach distress.

Most importantly, the choice of fluid should be something the athlete likes to drink, as drinking adequate amounts is critical.

Easy ways to monitor hydration status

The old adage, “If you feel thirsty, you’re already dehydrated,” is true on some level. But, the mechanism of thirst is complicated and can be associated with the level of dehydration. When it comes to kids and teens, knowing if you’re thirsty or not may not be an adequate gauge of dehydration.

Although the Institute of Medicine (IOM) supports the use of thirst as a gauge for when to drink, more recent studies have shown that young athletes may not be good measures of their own hydration status. They may not recognize thirst, or may deny it, being distracted by other events. For this reason, it is important for parents and coaches to remind (yes, nag!) young athletes to drink fluids.

If you suspect your athlete isn’t on top of his hydration, try these useful ways to check it:

Thirst: Using a scale of one to nine, with one being not thirsty at all to a nine being very, very thirsty, researchers have found that young athletes falling between a three and five likely had a 1 to 2 percent dehydration.

Urine Color: Urine color charts have been developed to help young athletes know when they are dehydrated. Ideally, young athletes want their urine color to be a pale yellow (like fresh-squeezed lemonade or lemon juice), indicating adequate hydration. A strong yellow, orangey-yellow or brownish green color (read: Mellow Yellow or Mountain Dew) means the athlete is dehydrated and drinking needs to begin as soon as possible. Researchers have also used urine color charts ( in locker rooms to educate about hydration, and have found them to be effective reminders for athletes to drink fluids.

Weight: A pre- and post-exercise body weight is another method for identifying dehydration. For every pound lost after exercise, 500 milliliters (16 ounces) of fluid should be consumed to replenish hydration status. For example, if a child’s weight is 110 pounds before practice and 108 pounds after practice, there is a two-pound loss of water weight and the athlete would need to drink 32 ounces of fluid.

Watch out for over-hydration!

Also known as water intoxication, over-hydration happens when young athletes drink too much, resulting in dangerously low sodium levels in the blood. This can lead to bloating, pale urine, swelling of the hands and feet, and headache. Advanced cases of over-hydration include nausea, vomiting, seizures and coma.

Jill Castle, MS, RDN is a childhood nutrition expert and co-author of Fearless Feeding: How to Raise Healthy Eaters from High Chair to High School ( ). She is the creator of Just The Right Byte ( ), a childhood nutrition blog. She lives with her husband and four children in New Canaan, Conn. Contact her at

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