Endocrine Responses to Exercise in the Developing Child and Adolescent.

The impact of exercise training on the neuroendocrine control of the pituitary in the developing child is complex and the exact mechanisms are not fully understood. Multiple determinants influence adaptive hypothalamic-pituitary secretory responses to physical stress, namely, training intensity and duration, nutrition and energy balance, gender, age, sex, and sexual maturation status. The increase in growth hormone (GH) in response to acute exercise is dependent on pubertal status; children in more advanced pubertal stages respond with larger peak GH concentrations compared to those in earlier stages. The adolescent female athlete is more prone to menstrual disorders than the more mature athlete, and recent data suggest that athletes may be able to reverse menstrual disorders by increasing their dietary energy intake without decreasing their exercise levels. The thyroid changes observed are of minor impact, practically reflecting the relative negative energy balance during strenuous exercise. Studies that evaluated changes in cortisol secretion during aerobic exercise in children and adolescents show either an increase or no change in response to the exercise bout. Recent research showed that physical activity is an important contributor to bone strength prior to adolescence and increasing levels of physical activity during childhood likely enhance optimal bone strength.