Researchers have shown a positive effect of growth hormone on athletic performance in a new study.
It showed a .4 second improvement in a 10-second sprint, enough to turn a last-place Olympic athlete in a sprint event - running or swimming - into a Gold medal winner.
The study justifies growth hormone being a banned substance, even though evidence of its performance enhancing effect has been very poor until now.
Growth hormone, produced naturally in the body, is important for growth and metabolism. Injectable growth hormone is available for people who have growth hormone deficiency. Many athletes use the drug because they believe that it bulks up their muscles and improves their physical performance (growth hormone "doping"). Until this study, no scientific research had been undertaken to show that growth hormone improves physical performance.
Researchers at Sydney's Garvan Institute of Medical Research demonstrated that growth hormone increases an athlete's ability to sprint on a bicycle, but has no effects on fitness, weight lifting or jumping. The effect on sprint capacity nearly doubled in men who received testosterone injections in addition to growth hormone supplementation.
The study looked at 103 healthy recreational athletes, aged 18 to 40 years, who had engaged in regular athletic training for at least a year. It was double-blind and placebo-controlled, meaning that neither the investigators nor the participants knew who was receiving the drug or dummy injections (salt water).