GH has been considered as an ergogenic drug since the late 1980s. Since that time, official and non‐official sources have reported that misuse in sport has steadily increased. The attractiveness of the product is based on popular knowledge that it is efficient, hard to detect, and without major side effects if well dosed. GH misusers primarily try to benefit from the known anabolic action of the drug, to increase their muscle mass and power.
The frequency of use and the dosage are hard to evaluate, but underground information suggests that the athletes misusing hGH take 10–25 IU/days three to four times a week to increase their lean body mass. We think that the mean dose is about 4 IU/day in combination with other doping agents, such as anabolic steroids in power sports or EPO in endurance sport. GH is often taken in cycles of four to six weeks, as is the case for anabolic steroids in bodybuilding. In endurance sport, little is known about the optimum utilisation of hGH doping in combination with other products. It is highly individual and empirical.
The effectiveness of rhGH in the improvement of sport performance is still under debate among users. The positive effects described in hGH deficient adults are not that clear among athletes. Although many of these underground reports indicate some positive effect on muscle mass, it is difficult to differentiate benefits obtained when hGH is taken in combination with anabolic steroids or even if the hGH used was a less effective product. The use of hGH as an anabolic agent still seems to be widespread, but it is difficult to investigate the extent of the phenomenon. It has been reported that 5% of male American high‐school students used or have used hGH as an anabolic agent.22
It is unknown how popular hGH is among female athletes, but some use has been reported because of the low risk of androgenic side effects that are seen with anabolic steroids. Not only is the anabolic effect of hGH favored by high power output athletes, but its use is also gaining acceptance in endurance sport in combination with methods for enhancing oxygen transport. Although there are anecdotal reports on the so‐called dramatic increases in muscle mass and strength after large doses of hGH (especially among bodybuilders) their effectiveness under controlled conditions is generally less impressive.
As the results of controlled studies are generally not in agreement with subjective underground reports by misusers, it is difficult to draw any definite conclusions regarding the effects of excessive hGH administration on skeletal muscle function. It must be stressed that the regimen of hGH use in sport is designed to fulfil purposes other than just an increase in athletes' muscle mass. The doses involved are certainly specific to a discipline, its training model, and tailored to the regimen of other ergogenic substances being used concurrently.
GH misuse is still expensive and the high costs and difficulty in finding the “right” clean drug have certainly pushed some athletes to use products claimed to enhance GH production. Among these are the amino supplements such as arginine, ornithine, lysine, and tryptophan, but there are no clearly established results. The effectiveness of rhGH is also widely discussed among its users in the underground literature or in internet chat rooms without a clear positive position. Several aspects can be debated, but because of its price, some proportionality in the effects is to be expected by the users. Certainly disappointments are due to bad dosing, not combining with anabolic steroids, or a too‐short duration of use.
There are few controlled studies on the effectiveness of GH on the performance of top level athletes. In general these studies have been performed with supraphysiological dosages but not with the large amounts claimed to be effective, for instance, by bodybuilders. The results of most of these controlled studies are generally less impressive than the claims of those who misuse the substance. A study of volunteers under heavy resistance training found decrease of free fatty mass but no difference in the muscle strength.23
With weight lifters, it has been shown that short term GH treatment does not increase muscle protein synthesis more than placebo24
or other factors such as maximal voluntary strength (biceps or quadriceps).25
These results conflict with reality, which is that rhGH misuse seems to exist in top‐level sport, because the compound is often found in police raids related to doping affairs. We believe that most of the time misusers will take rhGH as a part of their cocktail of specific preparations, rather than considering rhGH as a unique pharmaceutical preparation. The effects of GH on the metabolism are so widespread that one can be certain that this is taken in combination with other products. And the final effect generally occurs elsewhere, rather than in what is tested in the laboratories.