Working out to relax -- Fitness vacation is popular passion

(CNN) -- Calling a week's worth of sweating and jumping and pedaling an exclusive vacation may seem like a stretch.

But people are beating a path, even paying an average of $4,000 a week, to do just that at the Tucson, Arizona-based Canyon Ranch.

It's just part of the booming fitness business. The number of people belonging to fitness centers in the United States has grown from 13.8 million members in 1987 to 22.5 million members in 1997.

Fitness vacations just may be the next big market for the health conscious.

"If people don't like exercise, I would tell them not to come," said Canyon Ranch founder Mel Zuckerman. "I think it's the foundation; it's the most important building block of a healthy lifestyle."

Not 'pamper parlors or fat farms'

At Canyon Ranch, there's no smoking or drinking anywhere on the 70-acre campus. And fatty foods drenched in rich cream sauce are nowhere to be found.

Instead, people immerse themselves in vigorous workout programs -- everything from funk aerobics to "boxercising" -- hoping to find health and happiness in the process. But don't call it a "spa."

"It's not a spa," Zuckerman says. "Because I hate the word spa because it means so many different things. But most Americans think of spas as pamper parlors or fat farms."

Fitness-as-fun business is strong

He says Canyon Ranch and its sister resort in Lenox, Massachusetts have 90 percent occupy rates year-round. Analysts say that's about as good as it gets in the fiercely competitive spa business.

"It has a wonderful reputations, a wonderful following -- a staff-guest ratio of over two to one," said Scott Berman, a resort analyst with PricewaterhouseCoopers. "It's really one of the best spas in the world."

Positioning itself as a place for couples helped launch the resort, but experts say what separates Canyon Ranch from many in the industry now -- it's constantly changing, coming up with new classes and feel-good services aimed at aging yuppies.

Zuckerman has also added a medical wing with everything from bone scans to acupuncture. These sources of innovation are also important revenue streams as services guest pay for on top of the basic vacation package. One bone density test will add $375 to your bill.

"Those elements here are a significant profit center where they are not even tried at other destination spas," Zuckerman said.

Day spas are next

Canyon Ranch does not beat out other spas in all categories though. While massage and other beauty services are available, they are not the focus. And Zuckerman admits not all guest have been happy guests.

"Most of the problems with people who are unhappy are because they didn't realize it was a fitness resort," he says. "Their idea of aerobic exercise was getting in and out of the jacuzzi or putting their pantyhose on in the morning."

Even those who are Canyon Ranch devotees say there are limits.

"I sort of feel like I'm a captive after a while," said Canyon Ranch guest Ray Niro.

But once guest escape, they tend to come back for more.

"Unlike most vacations, you come back feeling better than you did when you left," Ray said.

Zuckerman has no plans to open any more U.S. "destination spas," his name for Canyon Ranch.

But in the works are plans for day spas that will be added to existing urban hotels. The first one is planned for the Venetian in Las Vegas.