Human growth hormone occurs naturally in the human body. Use of exogenous human growth hormone (HGH), via injection, was originally for medical purposes until athletes began abusing HGH with the goal of increasing their abilities. Before recombinant human growth hormone (rHGH) was developed in 1981, HGH was only available from cadavers. The arrival of rHGH combined with other peptide hormone advancements has increased the availability of HGH on both the legitimate and black markets. The first description of the use of GM as a doping agent was Dan Duchaine’s “Underground Steroid handbook” which emerged from California in 1982; it is not known where and when GM was first used this way. In 1989 the International Olympic Committee became the first to brand human growth hormone a banned substance. Although abuse of human growth hormone for athletic purposes is illegal in the U.S., over the past decade it appears that abuse of HGH is present in all levels of sport. This is fueled at least in part by the fact that HGH is more difficult to detect than most other performance-enhancing drugs, such as anabolic steroids. Athletes competing in power sports, bodybuilding, professional wrestling, mixed martial arts, swimming, baseball, strength sports, track and field, cycling, soccer, weight lifting, skiing and endurance sports have been said to abuse human growth hormone, including in combination with other performance-enhancing drugs such as androgenic anabolic steroids including testosterone, certain products which claim to enhance HGH, and erythropoietin (among others).
There has never been an adequately large randomized controlled trial showing definitively that HGH provides benefits to athletes and that there are no significant adverse drug reactions; there have been many small studies and several of these studies were recently reviewed and analyzed in a meta-analysis. While the authors indicated that the meta-analysis was limited by the fact that few of the included studies evaluated athletic performance and by the fact that dosing protocols in the studies may not reflect real-world doses and regimens, their conclusions were as follows:
"Claims that growth hormone enhances physical performance are not supported by the scientific literature. Although the limited available evidence suggests that growth hormone increases lean body mass, it may not improve strength; in addition, it may worsen exercise capacity and increase adverse events. More research is needed to conclusively determine the effects of growth hormone on athletic performance."
With regard to adverse drug reactions, there is data from animal studies that "long-term administration of human growth hormone can increase the risk of diabetes, retention of fluids, joint and muscle pain, hypertension, cardiomyopathy, osteoporosis, irregular menstruation, impotence and elevated HDL cholesterol."
A report from the United States House Committee on Oversight and Government Reform on steroid and growth hormone use found that the misguided use of HGH by professional athletes and entertainers was fuelling the industry peddling the drug to the general public for medically inappropriate uses.