Climatic Heat Stress and the Exercising Child

Abstract

Heat-induced ifiness is preventable. Physicians, teachers, coaches, and parents must be made aware of the potential hazards of high-intensity exercise in hot climates and of the measures needed to prevent heat-related illness in preadolescents. Because of the following morphologic and functional differences, exercising children do not adapt to extremes of temperature as effectively as adults when exposed to a high-climatic heat stress.1 1. Children have a greater surface area-mass ratio than adults, which induces a greater heat transfer between the environment and the body. 2. Children produce more metabolic heat per mass unit than adults when walking or running.2 3. Sweating capacity is not as great in children as in adults.3,4 4. The capacity to convey heat by blood from the body core to the skin is reduced in the exercising child.4,5 The foregoing characteristics do not interfere with the ability of the exercising child to dissipate heat effectively in a neutral or mildly warm climate. However, when air temperature exceeds skin temperature, children have less tolerance to exercise than do adults. The greater the temperature gradient between the air and the skin, the greater the effect on the child.4,6,7 Upon transition to a warmer climate, any exercising individual must allow time for conditioning for heat (acclimatization). Intense and prolonged exercise undertaken before acclimatization may be detrimental to health and might even lead to fatal heat stroke.8 Although children can acclimatize to exercise in the heat,6,9 the rate of their acclimatization is slower than that of adults.1 Therefore, a child will need more exposures to the new climate to sufficiently acclimatize.