Growth hormone no benefit to athletes: U.S. study

WASHINGTON (Reuters) - People who take human growth hormone in the hope of boosting athletic performance are not only breaking the law and risking their health, but likely are not even achieving their objective, U.S. researchers reported on Monday.

While some reports show that some illegal steroids may help athletes bulk up and train harder, human growth hormone is not one of them, the report in the Annals of Internal Medicine suggests.

"What we saw is that while there was a change in body composition, we didn't find evidence that growth hormone improves athletic performance," Dr. Hau Liu of Stanford University in California, who led the study, said in a telephone interview.

Liu's team looked at 27 studies covering 303 people aged 13 to 45. They found that, overall, those who took growth hormone did develop more lean body mass, but this did not translate to either more strength or exercise capacity.

People who took growth hormone had swelling of their tissues and more fatigue compared to people not taking the drug, they added.

Use of growth hormone is banned by the International Olympic Committee, Major League Baseball and the National Football League. U.S. law prohibits its use for sports enhancement.

When the hormone is given to people with growth hormone deficits caused by pituitary tumors or other conditions, it can improve strength. But it does not enhance strength in normal, healthy people.

For example, people given hormone generated more lactate, a byproduct of exercise that can cause pain and muscle fatigue. In one study meant to see if human growth hormone might boost strength or endurance, two cyclists given the hormone stopped a workout because of fatigue.

"The key takeaway is that we don't have any good scientific evidence that growth hormone improves athletic performance," Dr. Andrew Hoffman, a professor of endocrinology, gerontology and metabolism who worked on the study, said.

Hoffman noted that other hormones have been shown to benefit athletes -- notably testosterone.

"Athletes probably take much more hormone than the investigators felt that they could ethically try to give to healthy people; in addition, some athletes combine growth hormone with other anabolic hormones like testosterone," Hoffman added in an e-mail.

Hoffman said people get side-effects from high doses of hormones. "You get fluid accumulating in the legs, you get pain in the joints," he said in a telephone interview.

"From what we hear the athletes are taking very, very large doses," he added.

Other hormones do, however bulk up athletes -- although not without risk, Hoffman said. "The findings with growth hormone absolutely do not extend to other hormones like testosterone which work through entirely different mechanisms," he said.

(Reporting by Maggie Fox; Editing by Cynthia Osterman)