Dose-dependent Relationship Between Severity of Pediatric Obesity and Blunting of the Growth Hormone Response to Exercise. Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol] Journal article

In children, exercise modulates systemic anabolism, muscle growth, and overall physiological development through the growth hormone-->insulin-like growth factor-1 (GH-->IGF-1) axis. GH secretion, both at rest and during exercise, changes with age and maturational status and can be blunted by hyperlipidemia and obesity, with possible negative effects on physiological growth. However, little is known about the effect of progressively more severe pediatric obesity on GH response to exercise and its relation to pubertal status. We therefore studied 48 early or late pubertal obese children (BMI%tiles >95(th), separated in tertiles with progressively greater BMI) and 42 matched controls (BMI%tile <85(th)), who performed 10 bouts of 2-min cycling at ~80% VO2max with 1-min intervals. Plasma GH and IGF-1 were measured at baseline and end-exercise. GH responses were systematically blunted in obese children, with more pronounced blunting paralleling increasing BMI. While overall late pubertal subjects had a greater GH response to exercise than younger children, this blunting pattern was observed both in early and in late pubertal subjects. Our results reveal insight into the interaction between pediatric obesity and key modulators of physiological growth and development, and underscore the necessity of optimizing physical activity strategies for specific pediatric dysmetabolic conditions. Key words: adolescence, growth factors, adiposity, sexual maturation.

Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol]