A recent study conducted at the Garvan Institute of Medical Research in Sydney, Australia, showed that the growth hormone’s effects on athletes are rather mental than all physical.

The researchers observed the effects of the growth hormone on 64 athletes and how they responded to the treatment. The athletes who took part in the study were given either growth hormone, a completely inactive placebo or both. Of course, the athletes did not know who received what.

After 8 weeks of studying the athletes’ behaviour, researchers found out that the subjects who received a placebo but thought they were taking growth hormone felt an improvement in their performance.

The performance was boosted by approximately 1 to 2 percent in every athlete who received both growth hormone and a placebo, while the performance of athletes who were given just a placebo grew by nearly 5 percent.

"This is a very relevant finding of the biology of the mind," said study co-author Dr. Ken Ho, head of the pituitary research unit at the Garvan Institute of Medical Research in Sydney, Australia. He added that a positive outcome can be achieved (especially in a sporting context) just through the belief that one has been given something beneficial even if one actually hasn't.

The human growth hormone (GH) is a hormone that stimulates growth and cell reproduction in humans and other animals. There are several diseases which can be treated through the therapeutic use of GH. However, its use has also been linked to an increased risk for heart disease, diabetes, muscle, joint, and bone pain, high blood pressure, and osteoarthritis.