Growth hormone boosts sprinting capacity in athletes but may have serious side effects

By Dr. Ananya Mandal, MDMay 3 2010

Human Growth Hormone (hGH) has long been used among athletes and body builders for stronger and a more muscular bodies over the past four decades. However it is only now that Sydney-based researchers have published a study that shows that hGH offers no such benefits.

hGH is a hormone that the body normally produces and it helps in the development of muscles and organs. The study results show that hGH gives a 4% improvement in the stamina for running but had not effect on endurance, strength and fitness. One of the study volunteers also developed a condition called gynaecomastia or abnormal development of breasts in a male as a side effect to hGH. Fluid retention, bloating, pain in the joints were some other side effects experienced by the volunteers.

Professor Ken Ho from Sydney's Garvin Institute of Medical Research was the lead author of this study. He expressed his delight and surprise at the results. “The improvement in performance was observed in a selective aspect of physical function - that of sprint capacity…We did not find any effect on endurance, strength and power, which are areas of physical performance which most people expected growth hormone to work on,” he said. This study was funded by the World Anti-Doping Agency (WADA).

The study spanned over eight weeks and included 96 healthy, recreationally trained athletes with an average age of 27. The 63 male volunteers were divided into four groups with each getting;

• 2 milligrams per day of hGH
• 250 milligrams per week of testosterone
• Both hGH and testosterone
• Placebo injections.

The 33 female participants received either growth hormone or placebo injections. None of the participants or examiners knew who got what. All the participants then underwent physical and laboratory examinations.

At the end of the study results showed that hGH improved sprint capacity in men and women by an average of 3.9% over the placebo group. According to Dr. Ho this would cut down 0.4 of a second from a 10-second time in the 100-meter dash. Men who received both growth hormone and testosterone had an 8.3% average increase in sprint capacity, the study found. hGH also reduced body fat and made muscles leaner. The study was published in Annals of Internal Medicine this Monday.

A combination of Testosterone and hGH however in men could double the improvement in sprinting compared to hGH alone. David Howman, director general of the Montreal-based World Anti-Doping Agency commented that, “This is helpful in showing those skeptics out there who say it doesn't help performance that they're wrong.” He called these results a warning to U.S. professional sports organizations that have resisted testing for hGH hormone because they say the substance is too difficult to detect. This hormone can be detected in blood only if it is tested within a few days of use. Howman urged sports leagues to consider unannounced, out-of-competition testing. “They should wake up and see they should be putting a lot more effort into detection of this substance,” he said.

Dr. Gary Wadler, a professor of medicine at New York University and chairman of a WADA committee on banned substances went on to say that when testosterone is combined with hGH, both can be used at lower levels which can enhance performance but escape detection in urine or blood. “It's concerning that athletes could take levels low enough that it would not result in a positive urine testosterone test,” he said. He says that actually athletes use higher doses than used in the study. “We think the real effects of growth hormone are, or could be, far greater than what's reported in our paper…Equally, the side effects could be much more serious,” he said.

The WADA is now trying to develop and release a blood test this year that would identify markers for hGH. Howman also announced that this test would increase the time within which the drug can be detected from a few days to several weeks.