Journal Title (Medline/Pubmed accepted abbreviation): Sports Med.
Page numbers: 279-288
doi (if applicable):
Summary of the review
Dehydration occurs when one sweats to dissipate heat and then doesn’t drink enough water to compensate. Children were once believed to not be able to regulate their body temperature as well as adults while exercising, and especially while exercising in high heat. However, more recent data shows that children may not be more prone to dehydration than adults.
- Compared to men, prepubescent boys have been shown to sweat less (relative to their body size). This may be due to differences in male hormones (ex. testosterone). Adult and pre-pubescent females sweat similar amounts compared to one another and less than mature males.
- Dehydration causing a loss of 2% of body weight or greater leads to a decrease in performance in adults. In children, dehydration to 1% loss of body weight has been shown to decrease performance.
- There is a limited number of controlled studies done on the topic, but children have been shown to drink nearly enough fluids ad libitum (on their own) to replenish fluid loss during exercise. Adults, on the other hand, have demonstrated insufficient ad libitum fluid intake.
- Is water or a carbohydrate/electrolyte-containing sports beverage a better choice Children lose less sodium during exercise than adults due to less total sweat and a lower concentration of sodium in their sweat. So, sports beverages are probably not necessary for most child athletes to replace sodium, but they probably would not be detrimental either. Therefore, choice should be based to taste preference of the child. Carbonated beverages should be avoided to prevent bloating and juices should be avoided because they can cause delays in gastric emptying.
- In attempt to avoid dehydration, there have been a few cases of adults drinking too much water, thereby putting their serum sodium concentration at a dangerously low level (hyponatremia). Although this generally has not been reported in children, adults and coaches should be aware of this risk.
- Beginning an event under-hydrated increases the risk of dehydration. Therefore, assure that children are getting adequate fluids in between games and even in days between exercise bouts.
- The author provides a table of recommendations for fluid intake based on body weight. These recommendations are based on what children consume ad libitum. For example, an 80 lb. child consumes approximately 16 oz. per hour during exercise then about 5 oz. after exercise for every hour of prior exercise. The author also states that it is okay for the child to lose some weight during exercise.
Interpretation of findings/Key practice applications
Child athletes can typically rely on thirst to know how much liquid is needed to replenish loss during exercise. However, distractions, lack of beverage availability, etc. may cause a child to not drink enough. Parents and coaches should monitor fluid intake and the child’s performance to avoid dehydration. Provision of breaks in activity every 15-30 min for hydration and encouragement of the important of hydration are helpful to maintaining fluid status. For children who do not drink enough during exercise, fluid replenishment in the postexercise period is very important prior to subsequent exercise. The author suggests that the choice of water or sports beverage can be made by the child. However, recent concern raised by the American Academy of Pediatrics is that the caloric contribution from sports drinks may increase risk of weight gain/obesity. Thus, sports drinks for children should be reserved for situations in which they are truly needed in comparison to plain water.
The tables provide an estimate for child fluid intake, but there are many variables that factor into how much fluid a child should need: outside temperature, intensity of activity, how acclimated the child is to outside activity, normal fluid intake habits, etc. It is important to consider the individual needs of the child as opposed to always relying strictly on published guidelines for fluid intake.