A sedentary lifestyle has been linked to the development of cardiovascular disease, diabetes mellitus and obesity. Although these conditions are predominantly found in adults, they are lifelong processes with their origins in childhood. Therefore promotion of physical activity is important in pediatrics. Although some children may be too sedentary, others are participating in training programs and competitive sports that are inappropriate for age. Guidelines for sports participation must be based on a careful consideration of the child's physical fitness, developmental requirements and limitations.