MONDAY, March 17 (HealthDay News) -- In addition to ruining promising sports careers, human growth hormone may not even enhance athletic performance as it is purported to do.
An analysis of existing literature on human growth hormone found that while lean body mass increased, exercise capacity did not.
The findings add an ironic twist to the current controversy surrounding baseball greats Roger Clemens, Andy Pettitte and others.
Clemens has denied under oath using steroids and growth hormone, while Pettitte has admitted using human growth hormone to recover from injuries.
Last December, former U.S. Senate Majority Leader George Mitchell released a report affirming widespread use of performance-enhancing drugs in baseball.
"Our findings are consistent with the Mitchell report," said Dr. Hau Liu, lead author of the new analysis, which will be published in the March 17 online issue of the Annals of Internal Medicine.
The authors, however, warned of the difficulties of comparing use of growth hormone in a controlled study and use in the "real world."
In that so-called real world, dosages of growth hormone are probably higher, and the substance is often also taken in combination with other compounds, a practice called "stacking."
"This is not the final word," said Liu, an affiliated clinical assistant professor of medicine at Stanford University School of Medicine and associate chief of endocrinology at Santa Clara Valley Medical Center in San Jose. "This is basically a call for more research."
"Some people might use [growth hormone] by itself, and those may be looking more at the anti-aging benefit as opposed to performance enhancement," added Dr. Todd Schlifstein, an assistant professor of rehabilitation medicine at New York University School of Medicine in New York City. Many people take steroids along with growth hormone to maintain the benefit of the hormone, he said.
Liu's group had previously found that growth hormone had no effect on aging in healthy older people. "We said that we couldn't recommend its use for anti-aging purposes based on current evidence, because the risks outweigh the benefits," Liu said.
