Growth Hormone Overrated in Athletic Gains: Study

March 17, 2008— -- NEW YORK (AP) - Athletes who take human growth hormone may notbe getting the boost they expected.

While growth hormone adds some muscle, it doesn't appear toimprove strength or exercise capacity, according to a review ofstudies that tested the hormone in mostly athletic young men.

"It doesn't look like it helps and there's a hint of evidenceit may worsen athletic performance," said Dr. Hau Liu, of SantaClara Valley Medical Center in San Jose, Calif., who was leadauthor of the review.

Growth hormone, or HGH, is among the performance enhancersbaseball stars Roger Clemens and Andy Pettitte were accused oftaking in the blockbuster Mitchell Report. Clemens denies using thehormone, while Pettitte admits using it.

But the new research has some limitations and sheds no light onlong-term use of HGH. The scientists note their analysis includedfew studies that measured performance. The tests also probablydon't reflect the dose and frequency practiced by athletesillegally using the hormone. Experiments like that aren't likely tobe conducted.

"It's dangerous, unethical and it's never going to be done,"said Dr. Gary I. Wadler, a member of the World Anti-Doping Agencyand a spokesman for the American College of Sports Medicine.

Consequently, those in the field have to depend on such reviewsor "what we hear on the ground," he added.

Human growth hormone is made by the pituitary gland and promotesgrowth. A synthetic version has been available since the 1980s andits use is restricted for certain conditions in children andadults, including short stature, growth hormone deficiency andwasting from AIDS.

Although banned for other uses, growth hormone has been used bya variety of athletes and was cited along with steroids as one ofthe performance-enhancing drugs abused by baseball players in thereport in December by former Senate majority leader GeorgeMitchell. Several athletes, including Pettitte, have said they usedHGH while recovering from an injury, an issue not covered in thereview.

"There are a lot of claims that it's this wonder drug," saidLiu.

Wadler said one of the appeals of growth hormone for athletes isthat it can't be detected in a urine test. A blood test will beavailable soon, and another is in development, he said.

"They think they are getting a free ride - they aren't gettinga drug test," he said. "They believe they are stronger andbigger."

Liu and his colleagues at Stanford University sought to find outif growth hormone really could improve performance. They looked forthe best published tests, those comparing participants who got thehormone to those who didn't get the treatment.

They analyzed 27 studies involving 440 participants. The resultswere released Monday by the Annals of Internal Medicine.

Researchers found that those who got the hormone put on about 5pounds more of muscle, and lost about 2 pounds more of fat,although the fat loss wasn't statistically different. Theresearchers said some of the extra body mass could just be fluidbuildup.

There was no difference found in strength or exercise staminabetween the two groups, but there were only two strength studiesand eight that measured exercise. Those who got the hormone hadmore side effects including swelling and fatigue.

The review couldn't consider long-term effects, since thelongest study was three months, and most were much shorter.

The researchers also said the doses used in the research may belower than those used by athletes, who may be combining growthhormone with other performance-enhancing drugs.

Dr. Alan Rogol of the University of Virginia and the IndianaUniversity School of Medicine, said the work was a good review buthad to rely on inadequate research.

"There are just tons of things we don't know," said Rogol.

The California researchers had support from Stanford, governmentagencies and Genentech Inc., which makes growth hormone; none ofthe groups had a role in the study. Two researchers also have beenconsultants or received grants from Genentech and other drugmakers.

---

On the Net: Annals of Internal Medicine: http://www.annals.org/