The prospect that athletes will soon try to enhance their bodies with gene technology is raised by the results of a new study to boost muscles in rats.

The scientist behind the research says his intention was to find new ways of treating muscle wasting diseases.

But Lee Sweeney, from the University of Pennsylvania, says trainers are already making inquiries about his technology.

"I would say half the e-mails I get now are from athletes," he told an American science conference in Washington State.

"The other half is from patients with muscular dystrophy."

Sweeney and colleagues injected their rats with a virus which carried a gene into muscle cells to produce a growth hormone called IGF-I.

The rodents given the therapy and put on an exercise programme developed bigger and stronger muscles.

The scientists also found the rats with genetically elevated levels of IGF-I retained more of their muscle mass after they stopped exercising.

All this could be of considerable help to patients with muscular disorders and muscle loss associated with either disuse or ageing.

But the benefits are also those that athletics cheats have sought in the past from standard drug technologies.

Hijacking research

While the leap from laboratory animals to human beings is still hypothetical, Lee Sweeney and other speakers here at the annual meeting of the American Association for the Advancement of Science said it was inevitable that athletes and their trainers would attempt to hijack the rat research.

"The world anti-doping code at the moment includes gene transfer technology as a banned practice," said Dick Pound, the chairman of the World Anti-Doping Agency.

"We're not sure of course we can detect it. Today, in fact, it would be quite difficult."

The speakers suggested that any clinical trials of new gene technologies to treat disease might include a requirement on the part of scientists to develop a test that could also be used on sports people to check there is no abuse of the research.

"The only way to detect this would be through a muscle biopsy," said Sweeney, an associate professor of physiology at Penn.

Thomas Murray, a bioethicist and president of The Hastings Center in New York, has looked closely at the issue of drugs in sport. He said sports administrators would have to raise their game yet again.

"Performance enhancing drugs in sport have posed a challenge to what we care about in sport - what gives it meaning," he told the meeting.

"Gene transfer technologies have the potential to kick it up a notch and make the challenge even greater."

Gene therapy has had a chequered history. It has long promised to revolutionise medicine by correcting or replacing faulty genes in patients - to cure diseases for which current drugs will only treat symptoms.

Haphazard technique

But the process of getting corrected genes into patients' cells can be haphazard, and clinical trials have resulted in at least one death.

Two boys in France treated for X-Scid, popularly known as "bubble boy disease", developed leukaemia.

Pound said it was essential that sports governing bodies worked with science to make sure the fruits of the genomic age went solely to diseased patients and not to gold medal frauds.

"In terms of these genetic applications, we're at the beginning of the cycle," he said.

"In the 60s, 70s, 80s and even the 90s, sport rather lost control of drug use. We've been playing catch-up ever since - with some success. What we'd like to do with this new branch of science is be there early to help in the formation of the regulation of it."

The rat research will appear in the March 2004 issue of the Journal of Applied Physiology.