Australasian Science: Australia's authority on science since 1938

Growth Hormone Works in Part

By Stephen Luntz

The first scientific evidence that human growth hormone (HGH) benefits athletic performance has been produced. However, the effect is surprisingly narrow.

HGH is a banned substance for elite athletes, but difficulties in distinguishing supplements from the body’s own HGH production have allowed its abuse to flourish. However, until now there has been no evidence that it actually works. Given that side-effects may include cancer and diabetes, properly controlled studies are difficult.

However, Prof Ken Ho of the Garvan Institute of Medical Research managed to get ethics committee approval for such a study. “My staff attended student clubs, sports clubs and so on. It took us a year to get 100 participants,” Ho says.

Half those taking part injected HGH every day for 8 weeks, while the rest received a placebo. The dosage was lower than cheating athletes are believed to use, but three or four times what the body produces naturally. Participants were warned of the possible effects, and told not to take part if they engaged in competitive sport where usage is banned. “We would have loved to have recruited professional athletes, but that wasn’t possible,” says Ho.

Contrary to promoters’ claims, no increase in muscle mass, strength or jumping capacity was observed in those using HGH relative to the placebo. However, HGH users did improve their spring capacity by 4–5%, enough to make the difference between coming last in the Olympic final and winning gold.

Ho says the team is “still working on” unravelling why there was a benefit for some purposes but not others. “We think it has something to do with the energy required to drive muscle performance at the start of a sprint event,” says Ho. “We think HGH provides energy to sustain muscle capacity.”

While it is possible that higher doses or a longer period may have revealed more widespread benefits, the study found evidence for side-effects. “Growth hormone recipients retained body fluid and experienced swelling and joint pain, unlike those who received salt water injections,” Ho says.

The dosage and period were chosen based on a range of factors, based on a balance of logistic and ethical considerations. “Only three people dropped out,” says Ho. “In many ways were quite lucky to have completed this.”