Infants’ and young children’s bodies contain more water (75%) than those of adults, and are more vulnerable to dehydration4. The higher surface-to-volume ratio of their bodies allows for greater water loss through the skin. Since their kidneys are not fully mature, they excrete more diluted urine, which means that they lose more water than they retain.
Young children also have more difficulty recognizing and communicating their need for water. Infants and young children are at higher risk of illness than adults; fever, vomiting and/or diarrhea can rapidly result in dehydration. They rely on their caregivers to supply sufficient water to protect their health.
Keeping children hydrated during exercise
Children’s response to dehydration is different than that of young adults. Thermoregulatory systems in children are not as developed as in adults, and children are less resistant than adults to high climatic heat stress. Children often do not voluntary drink adequate amounts of fluid during physical activity and can dehydrate easily, becoming overheated faster than dehydrated adults in the same environment.
Since children may lack motivation for proper fluid intake, parents, caregivers and coaches must ensure that young children receive appropriate hydration during and after exercise5.
Drinking water should be provided whenever children are physically active. Outdoor physical activity should be avoided under extremely hot conditions, particularly when radiant heat is at its peak.
Sources: (4) Jéquier et al. Water as an essential nutrient: the physiological basis of hydration. EJCN 2010, 64: 115-23; (5) Naughton et al. Reducing the risk of heat-related decrements to physical activity in young people. Journal of Science and Medicine in Sport 2008, 11: 58-65