NEW YORK (Reuters Life!) - They may look like upscale torture chambers in polished wood, but the Gyrotonic studios springing up in cities around the world aim to ease your pain, not to cause it.

Ironically, relief, fitness and alignment comes via a daunting arrangement of pulleys, levers and cranks.

"It looks like an erector set," Dr. Mark Klion, a sports medicine specialist at Mount Sinai School of Medicine in New York City, said of the combination pulley tower unit, the basic machine of Gyrotonic.

"Most people would say, 'Well, what do I do with this?'" he said in an interview.

Nevertheless, movie stars, athletes, dancers and just plain folk have been flocking to these contraptions and the dimly-lit dungeon-sized studios that house them.

Derived from the words "gyro" (spiral) and "tonic" (tone), Gyrotonic promises to enhance range of motion, balance and coordination, to stretch and strengthen muscles and tendons, and to articulate and mobilize joints.

"The machines are built around the body and allow the body to move with no end point," Matt Aversa, vice president of Gyrotonic International, explained.

"Nothing's forced. It's like you're swimming," he said from the company's headquarters in Dingmans Ferry, Pennsylvania.

Developed in 1970's by Hungarian dancer Juliu Horvath, Gyrotonic began as an advanced level of yoga. Its machine-less progenitor, Gyrokinesis, is called "yoga for dancers."

Gyrotonic uses yoga-like breathing techniques, but unlike yoga the body does not pause to hold a pose.

"With Gyrotonic, the body is always in resistance but there is no jarring. It continues to move fluidly," said Aversa, adding that 989 Gyrotonic studios operate in the United States today, up from 107 10 years ago.

Dr. Justine Bernard, of the Elements Fitness and Wellness Center, in Washington, D.C., uses Gyrotonic for rehabilitation, as well as fitness.

"Patients with scoliosis have decreased their curvatures. People with osteoporosis have increased their bone density. People with low back pain now move freely," he said.

"In Korea and Germany there are hospital-based Gyrotonic centers," Bernard added.

Gyrotonic studios exist in 46 countries, according to the company.

Klion, who calls Gyrotonic "Pilates' close cousin," is not surprised by its popularity outside the United States.

"It's about the philosophy of the healthcare industry. In Europe and Asia more holistic treatments are routinely offered."

Klion endorses Gyrotonic within limits.

"If you have strength but need to increase mobility & flexibility, then doing the pulleys that require complex motions makes sense," he said.

But he cautions that it's not for everyone.

"I definitely think there are dangers. For one thing, you need to go to someone who is educated. You need to be guided." And that can be pricey."

Aversa agrees. "You must start out with private lessons," he said, adding that they range from $45-$75 each. "After that, there are group classes."

Devotees can buy the machines which cost about $4,800, a steep rice for many in cost-cutting times.

But there is also Gyrokinesis, the low-tech alternative, where, according to Aversa, "all you need is a chair and a stool and a mat."