"Winners Never Quit" is the motto emblazoned above mirrors in the bodybuilders' gym, a series of small rooms filled with rubber mats, heavy lifting equipment and sweaty bodies pumping iron.

However, complete dedication to be a winner can take you only so far, the London gym's trainer says.

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Anyone wanting to go beyond their body's "genetic potential" will need to take steroids.

"We're supposed to think steroids are dangerous but if that's true - how come all these professionals use them?" said the trainer, who asked to be identified only as Jonny.

Steroids are banned in most professional sports but they are the bread and butter of bodybuilding.

Steroid use is linked with aggression, acne, headaches and liver and kidney damage, yet this does not seem to worry men and women yearning for the "perfect" body.

"I want to keep putting on muscle, and it's just not possible without steroids. I mean, look at those guys," Jonny said, nodding towards photos of champion bodybuilders grinning tightly and flexing impossible muscles.

What is worrying medical experts is that steroid use is no longer confined to aspiring Arnold Schwarzeneggers.

Youngsters are increasingly turning to the drugs to increase bulk and pump up their self-esteem.

Linda Johnstone, co-ordinator at one of the country's few health clinics for steroid users in Liverpool, said that in the last five years there had been a huge increase in the number of young men using their service.

"For older users, it's about performance. The younger users just want to look good. They want a six-pack (stomach) and good pecks (pectorals), and they want it now," she said.

"It's not about being huge," said one 20-year-old user. "You want to look your best. How else will you impress the ladies?"

GRUELLING TRAINING

"It's the individual's choice whether to take steroids," Jonny said.

"Most people don't even realise what it's about. It's more dangerous when there's a lack of knowledge about them." He says his own knowledge comes from talking with other users and swapping books and articles.

Johnstone, whose clinic saw around 200 clients last year - some from hundreds of miles away - says trustworthy information can be hard to find.

"Lots of the new users are led by older users and they don't realise there are health risks associated with it," she said.

The clinic provides clean needles and syringes, teaches people how to inject safely, and also gives advice on health issues associated with steroid use.

"One problem is that they don't classify themselves as drug users," she said.

Lee Monaghan, one of the few academics to have investigated steroid use, explained that because the drug is used for physique enhancement instead of getting a high, the 'drug-taker' label is rejected.

Users, Monaghan said, insist they follow a healthy lifestyle and often do not accept that steroid use carries dangers.

"Young men are much more difficult to give health advice to," Johnstone said. "They hear what they want to hear - they'll often be interested in health to a point, but if you tell them it's affecting their liver they don't want to know."

One of Jonny's clients, a 30-year-old working in the financial sector, insisted that being a member of a steroid-using network was the safest way of getting information.

"You're armed with knowledge being in a gym with people using steroids," he said. "It's the people buying steroids online with no idea what they're getting or how to use it you should worry about."

PERFECT BODY

Internet drugs sales are responsible for another trend, according to a British drug treatment charity - the use of opiate-based painkillers to allow users to push their muscles beyond the normal pain limit.

The introduction of more drugs has reopened the debate on how addictive performance-enhancing drugs actually are.

"There's a growing body of evidence to suggest that steroids might be addictive, but not physically," Johnstone said.

"A lot of it is about body image. We think people start with a poor body image and achieve a very tight muscular body in a very short period of time and they think that if they stop using steroids they'll get back to where they were before."

"Steroids are not physically addictive," insists Jonny. "I don't have to use them again.

"But it is psycho-addictive. I don't need them physically, but I want them.

"I want to be bigger."