Growth hormone and exercise: physiology, use and abuse.

This review summarizes the interactions between growth hormone (GH) and exercise. Exercise has profound effects upon the GH-insulin-like growth factor I axis per se. In addition, there is increasing evidence that such physiological perturbations might be influential in the performance responses to repeated training. However, the ergogenic effects of systemic administration of recombinant human GH by athletes and bodybuilders remain unproven. What is certain is that the prevalence of GH abuse by sportspeople will increase, not least because it is currently undetectable. The frequent and potentially severe side-effects associated with such 'doping' will be of increasing relevance to endocrinologists.