It may sound like the stuff of the Seventies television series The Bionic Man: a simple injection that increases the strength of a man by 40 per cent in just weeks.

But as much as it sounds like a superhuman fairy tale, the reality is in fact a real-life medical miracle.

After 15 years of research, scientists, lead by Professor Geoff Goldspink at the Royal Free Hospital in Hampstead, have developed a groundbreaking technique that can greatly increase human capabilities.

But in this case it is done, not by fitting robotic limbs as with the television character Steve Austin, but by injecting genes into wasted muscles, giving them a new lease of life.

The implications are huge: a possible cure for muscular dystrophy, a potential goodbye to motor neurone disease, and a significant boost to the lives of cancer, AIDS, stroke and heart attack patients.

After being successfully tested on mice, it is now ready to be trialled on people. Better still, within just five years it could be widely available through the NHS, thanks to interest from a large pharmaceutical conglomerate which is looking to mass produce the product.

"I intend to retire in about three years' time, and I expect to see it being administered by then," said Professor Goldspink.

It works by injecting a gene, that is naturally produced when we exercise, into wasted tissue. This gene activates the muscle stem cells, which in turn increase the production of a protein called mechano growth factor (MGF).

MGF boosts muscle mass and improves its ability to grow and repair itself.

"The gene which we have cloned turns out to be more of a repair factor rather than just a growth factor," explains Professor Goldspink.

"It makes this a very good candidate for therapy for muscular dystrophy, especially as we have found a way to introduce this growth factor into the body systematically so that it affects all muscles, not just the one that has been injected," said Professor Goldspink.

It's important to realise though, that it is not Professor Goldspink's intention to create a brand new world' of superhuman men and women.

The treatment is intended to give a fighting chance of survival to people with incurable long-term illnesses, such as muscle-wasting diseases like motor neurone disease, which killed the actor David Niven and the football manager Don Revie.

The disease affects nerve cells in the brain and spinal cord, and as the motor neurones gradually die, the muscles stop working, leading to a slow death.

It kills at least three people a day in the UK alone, with half dying within 14 months of diagnosis.

"Every week I get emails from people with muscle-wasting diseases for which there is no treatment. It would be great to be able to do something to help save these people from what can be a dreadful, lingering death," said Professor Goldspink.

As for those within organisations that have day-to-day dealings with the disease, there's a more tentative welcome.

Belina Cupid, research co-ordinator of the Motor Neurone Disease Association said: "We welcome any advances in medical research done by Professor Goldspink, and hope for more effective treatment of motor neurone disease in the future."

However, she adds: "Gene therapy is a very new treatment, and we would support such treatment if it's fully investigated for this study."

Gene therapy has also had its fair share of criticism when it comes to cancer, and in some cases has actually been blamed for increasing the growth of cancers, although Dr Goldspink denies his form of gene therapy will have this side effect.

"It's largely confused with another treatment which can cause already cancerous cells to increase, but this treatment has a difference sequential DNA and a different protein gene and therefore does a different job, and is unlikely to cause cancer."

Instead, he said the treatment can actually help cancer patients.

"By counteracting the muscle loss associated with their diseases, it will make chemotherapy more effective."

Dr Kat Arney, science information officer at Cancer Research UK, welcomes the developments, but is cautious.

"Any new treatment must be tested thoroughly in clinical trials before we can tell if it will be safe and beneficial to cancer patients, and gene therapy is no exception," she said.

So, although welcomed by the medical world, albeit tentatively, sport is one specific field into which experts all hope the treatment will never encroach. However, the abuse of the treatment to boost the performance of athletes is, according to Dr Goldspink, inevitable'.

"It will, absolutely, be abused by athletes," he said. "It will be misused because is has such an incredible effect on muscle growth."

The potential problem has already worried the International Olympic Committee, which has provided Dr Goldspink's team with a grant to find a way of detecting when the drug has been administered to athletes'.

In the same way steroids were developed in the 1930s to help elderly men regain strength, and, more recently, the use of a man-made copy of a naturally occurring substance EPO Epoetin, which stimulates the production of red blood cells and boosts oxygen in the body, gene therapy is likely to be on the list of medical advances to be abused by athletes.

The problem with gene therapy, and other naturally occurring substances, is that they cannot be put on the World Anti Doping Agency's banned list unless a way of detecting it has first been developed.

Peter Matthews, president of Enfield & Haringey Athletics Club and author of the International Athletics Annual said: "It's a good thing for treatment of wasting illnesses, but when it comes to athletics it needs to be detectable. That is a concern, and there have to be some rules drawn up."

The difficulty lies in whether athletes use the treatment legitimately, for example, when treating an injury, or whether it's used to encourage illegitimate muscle strength.

"In that case it creates a very unfair playing field," he said. "It's obviously a big problem for sport."

Bryan Smith, non-executive director of UK Athletics, and head of Endurance Competition in UK Athletics, as well as manager of Copthall Management Services, knows only to well the impact drug taking can have on sport.

He said: "Drugs, often those naturally occurring in the body and used to boost the performance of athletes, are used mostly for endurance events such as cycling and long-distance running." Many athletes, for example Paula Radcliffe, adopt legal' practices, including high altitude training, to help boost haemoglobin in the blood. But when it comes to gene therapy to boost performance, the line of acceptability is clearly crossed.

"However, how will we know?" he said. "The problem is that unless there's a way of detecting the drug has been taken, there is no way of stopping it."

So, what may be great news for the families of terminally-ill patients, could herald a new headache for sports administrators.

Mr Smith concludes that with gene therapy, the world of sport is skating on thin ice.

"Nine out of ten treatments abused by athletes tend to be those developed for medical use," said Mr Smith. "But it's opening a huge can of worms."