Heat illness. Fluid and electrolyte issues for pediatric and adolescent athletes.

The primary mechanism for maintaining normal body temperature during physical exercise in the heat is the evaporation of sweat. With profuse sweating, water loss far exceeds electrolyte loss. Rigorous exercise in the heat places the athlete at risk for thermoregulatory dysfunction from dehydration. Because children are inherently less efficient thermoregulators than adults, they are at even greater risk for heat illness. The three primary syndromes of heat illness are heat cramps, heat exhaustion, and heat stroke. Treatment of heat illness is based on reduction of body temperature and rehydration. Heat stroke is a true medical emergency with a high mortality rate; immediate reduction of body temperature is critical to the survival of these patients. Prevention of heat illness is based on reducing known risk factors. Physical activity should be modified in the face of high ambient temperature and humidity. The athlete should begin exercise well hydrated; frequent consumption of cold water during exercise decreases likelihood of significant dehydration. After exercise, the athlete should continue drinking to replace fluid losses. Clothing should be lightweight; the more skin exposed, the greater the available evaporative surface. A preseason conditioning program, when combined with an 8- to 14-day period of acclimatization, further reduces the risk of heat injury. Although athletes engaged in endurance sports may benefit from drinking carbohydrate/electrolyte-containing solutions, for the majority of young athletes, cold water remains the preferred choice for fluid replacement during exercise. The relatively greater body surface area of young athletes also places them at risk for hypothermia. Special attention should be given when these athletes are competing under cold environmental conditions.