Sports Doping's Effect May Be in the Mind

June 18 -- TUESDAY, June 17 (HealthDay News) -- When athletes think they are taking a performance-enhancing drug, their performance tends to get better -- even if they never really take the drug.

So concludes a study of recreational athletes, half of whom received human growth hormone supplements while the other half took a placebo.

"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. "There is a very real placebo effect at play in a sporting context, in which a favorable outcome can be achieved purely on the basis of a belief that one has received something beneficial -- even if one hasn't."

Ho and his colleagues were expected to present their findings Tuesday at the Endocrine Society's annual meeting, in San Francisco.

Human growth hormone (HGH) is produced naturally by the anterior pituitary gland at the base of the brain. It is a key player in the regulation of muscle, skeletal, and organ growth. The hormone also helps process calcium and protein and stimulates the immune system.

As an injectable supplement for the purposes of boosting athletic performance, the use of HGH has been on the rise in recent years. But the World Anti-Doping Agency (WADA) notes that its use has also been linked to an increased risk for heart disease, diabetes, muscle, joint, and bone pain, high blood pressure, and osteoarthritis. WADA has therefore classified HGH as a banned substance both in and out of sports competitions.

The drug made headlines early this year when baseball great Roger Clemens denied using HGH in testimony presented at special Congressional hearings on doping in professional baseball. His former New York Yankees teammate, pitcher Andy Pettitte, has admitted to taking the drug.

Since 2004 a blood test has been in place to screen out those athletes engaged in surreptitious use. At the endocrine meeting, a separate team of researchers from Ohio University and the Aarhus Kommunehospital in Denmark presented evidence -- derived from a mouse study -- that points the way toward a new group of more easily identified biomarkers for HGH, which, theoretically, could lead to improved HGH screening down the road.