NEW YORK -- Researchers are reporting the first scientific
evidence that a hormone banned in sports can boost athletic
The improvement from human growth hormone was modest, and only
in sprinting. It didn't increase strength or fitness. Athletes
likely to benefit are those in sprint events like running or
swimming that require a burst of energy, and where a split second
can decide the winner, the Australian researchers said.
Human growth hormone, or HGH, is one of many substances banned
by the Olympics and other sports even though there hasn't been any
good proof that it can enhance performance. Previous studies in
athletes have been small and brief.
The new research tested it in about 100 recreational athletes
for two months.
"This is the first demonstration that growth hormone improves
performance and justifies its ban in sport," said Dr. Ken Ho, who
led the study at the Garvan Institute of Medical Research in
Human growth hormone is made by the pituitary gland and promotes
growth of bone and other tissue. A manufactured version is
available, but its use is restricted to certain conditions in
children and adults, including short stature, growth hormone
deficiency and wasting from AIDS.
Growth hormone has been used by athletes in the belief that it
builds muscle and improves performance. It's also harder to detect
than other substances because it doesn't show up in urine tests.
There's been a blood test for growth hormone since 2004, but it
hasn't been used much outside competition.
In February, a British rugby player became the first athlete to
be suspended for using growth hormone after he was tested. A few
baseball players have admitted using growth hormone, including
former home run king Mark McGwire who recently apologized for using
it during his career.
The latest research involved 103 male and female recreational
athletes between 18 and 40. For two months, they got injections of
either growth hormone or salt water. Some of the men also got
testosterone, which is also banned in sports and often used with
They lifted weights, jumped and rode exercise bikes to test
their physical performance. Growth hormone didn't improve strength,
power or endurance, the researchers said. The only improvement was
for sprinting on a bicycle, a 4 percent increase in sprint capacity
compared to those who didn't get the hormone. In men who also got
testosterone shots, there was an 8 percent increase.
The researchers speculated that the boost from growth hormone
alone is enough to shave off about half a second in a 10-second
sprint over 100 meters. That little time "divides the winner from
the last place finisher," said Ho.
The study volunteers who took growth hormone lost body fat and
gained lean body mass, but it was mostly from water retention, not
from bulking up muscle, the researchers reported in Tuesday's issue
of the Annals of Internal Medicine.
Side effects included swelling and joint pain.
The researchers noted some limitations. They couldn't test the
hormone in elite athletes for ethical reasons, and they used a
smaller dose for a shorter time than reported for illegal use.
Larger doses and longer use might have more impact and more serious
side effects, they said.
"It's not a trivial thing to do a study like this. I think they
did a very good job," said Dr. Andrew Hoffman of Stanford
University, who was involved in a 2008 review of growth hormone
The director general of the World Anti-Doping Agency, which
helped pay for the study, said the results aren't surprising to him
and will disprove skeptics who don't think the hormone helps.
"There's been a huge amount of anecdotal evidence to indicate
that it is of advantage, and a huge number of athletes have used
it," said David Howman in a teleconference from Montreal.
Dr. Gary Wadler, who heads the committee that decides the
agency's banned-substances list, said growth hormone usually isn't
used alone. He said he's concerned that athletes will use the small
boost from growth hormone to keep their testosterone use below