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Sport Nutrition in Childhood: Meeting the Metabolic Demands of Growth and Exercise

The primary goals of childhood are optimal growth and maturation. These developmental processes demand positive energy and nitrogen balance. Regular physical activity can enhance childhood development; however, strenuous physical training may reduce the body’s stores of energy and nitrogen, both of which must be replaced through the diet. Physically active adolescents are susceptible to disordered eating, which can lead to protein-energy malnutrition. The consequences of negative energy and nitrogen balance include delayed, retarded or arrested growth and pubertal maturation. Currently, there is scant evidence to suggest that physical training has a direct negative impact on growth and maturation. A well-balanced diet is essential for the maintenance of physical performance and the preservation of health in all physically active individuals, regardless of age. Food provides the chemical elements required for the production of energy by exercising skeletal muscle, the post-exercise replenishment of fuel stores and the regeneration of damaged muscle. The dietary requirements of physically active children alter with increasing body size and pubertal progression. The maturation state is an important determinant of the metabolic and physiological responses to exercise, and so influences both physical performance capacity and dietary needs. Studies of fuel metabolism in children suggest that they are well equipped for sustained aerobic activity, but that their capacity for anaerobic performance is limited by their maturation state. Importantly, ethical restrictions preclude the type of detailed and invasive research that has identified the nutritional requirements of physically active adults. Nevertheless, it would seem that like such adults, physically active children have greater dietary demands for energy, carbohydrate, protein and water than their sedentary counterparts. This article justifies the nutritional requirements of athletic children on the basis of the physiological and metabolic demands of survival, growth and physical activity.