Yet GH abuse has become a widespread problem in many sports, including baseball, cycling, and track and field. What are the true gains and health risks?
Randomized clinical trials were performed, where athletes that administer GH or a placebo were compared to healthy young athletes, and then body composition, strength, and exercise capacity were measured and assessed in the lab.
After having been maintained on daily GH injections for an average of 20 days, the subjects who received GH showed an overall in their lean body mass (which reflects muscle mass but can also include fluid mass) by an average of 11 kg. This muscle mass gain is significant— but it did not translate into improved performance. In fact, GH did not produce measurable increases in either strength or exercise capacity. And the subjects who got GH had a higher propensity to retain fluid and experience fatigue than were the volunteers who got the placebo.
Among its many biological effects, GH promotes an increase in muscle mass and a decrease in body fat. GH levels drop with aging, with a parallel reduction in muscle mass and increase in body fat. And so, the theory goes, the way to arrest these effects of aging is to inject GH.
GH injections, which by no means are cheap, are offered by many practitioners for anti-aging, body building, or athletic enhancement. This is simply illegal and illegitimate, as this kind of intervention has not been extensively studied to prove its efficacy and safety.
To evaluate the safety and efficacy of GH in healthy older people, research studies published since the 1980s were reviewed. It was found that the subjects who received GH injections, when compared to the subjects who did not get GH, gained an average of 11 kg of lean body mass, and they shed a similar amount of body fat. There was a slight drop in total cholesterol levels, but no significant changes in LDL ("bad") cholesterol, HDL ("good") cholesterol, triglycerides, aerobic capacity, bone density, or fasting blood sugar and insulin levels. Yet no good deed goes unpunished: GH recipients experienced a high rate of side effects, including fluid retention, joint pain, breast enlargement, and carpal tunnel syndrome. The studies were too short to detect any change in the risk of cancer, but other research suggests an increased risk of cancer in general and prostate cancer in particular.