When New Zealander Matt Lewis opened his first gym in Beijing, his staff had no idea how to work the expensive new weights machines imported from the United States.

And among the first 50 members were women who would turn up for group fitness classes in their high heels. "People had no idea," he says. "It was all new for them."

As other industries have struggled with the recession, Lewis has led the expansion of the Chinese fitness industry to the point where an estimated 2.9 million Beijing citizens now belong to a gym. In 2001, the city had two Western-style fitness clubs; now it has more than 400.

In New Zealand, too, the big gym chains have reported membership growth of between 3 and 10 per cent, year on year, and record growth in the first three months of this year. Fitness NZ boss Richard Beddie has described the industry as "recession-proof".

Why, when everyone is watching their cents, are they are willing to spend their dollars on gym memberships?

Beddie can't be certain, but he has his own theory: "In a recession, for the 95 per cent of people who still have a job, a gym membership is relatively cheap."

Fewer people are willing to pay extra for personal trainers, he says, but paying $20 a week for a basic gym membership isn't much more than buying a coffee each morning.

"It can give people an escape, somewhere to go when work is proving stressful. Exercise makes you feel better about yourself. And that's a big thing in tough times."

It's also profitable for the gyms. In Beijing, Lewis' two Evolution Fitness gyms have been earning $2 million a year. He is now selling them and has started a consultancy, advising city gyms on how to turn a profit.

Lewis, 38, is originally from Otorohanga. His last job in New Zealand was as a coaching co-ordinator at Te Awamutu Sports and Recreation Club, but he has spent the past 12 years in China.

He turned up there speaking no Chinese, with nothing but a job offer to work at a hotel health club.

He rapidly realised Chinese people could only get a gym work-out by checking into an expensive business hotel, or by visiting run-down and unsavoury neighbourhood weights clubs. "You would have got a lot of barbells, a few benches, and not too clean. It's like what you'd seen in New Zealand 30 years ago," he says.

So he bought an office building with a swimming pool, knocked out the internal walls and installed expensive work-out machines and a juice bar. He opened with 50 members, and grew steadily till 2003. Then the Sars virus hit, and the Chinese Government closed all communal sports facilities for two months. Yet that was only a temporary hurdle, and by this year his two gyms had 4000 members.

Most of the city's 400 gyms are now advertising staff vacancies: there aren't enough qualified trainers to fill the jobs. "It amazes me how fast it's grown," Lewis says. "But then, there are a lot of things that amaze you in China."