Only a few feet away, though, one room was almost entirely silent, and the yoga workout leader, Yirser Ra Hotep, wasn't telling his class to speed up. In his soft, insistent voice, he kept urging his pupils to slow down. "Breathe in, and with your exhalation, lean over to the side. Slowly, turn your heel from the side to the front," he told his class. Behind him, three women and three men slid slowly but gracefully into their next position.

These members chose yoga over the bustling class next door because they wanted to improve their flexibility, to combat nagging injuries and they were curious, but mostly because they had been busy all day and wanted to find something to help them calm down.

While the benefits of yoga are plentiful -- and sometimes miraculous -- most students and teachers come back to that basic point. Yoga teaches them how to relax and how to take control of their lives.

A Key to Relaxation
"It's really calming at the end of a stressful day," says Tracy O'Bannon, a Chicago product manager who attends two classes a week. "Usually I come in worrying about work, and by the end everything's just kind of gone. You're releasing all your pressure."

The key to that relaxation, says Hotep, is yoga's emphasis on controlled breathing. "Yoga helps you learn immunity to stress," says Hotep, who offers video and audiotapes about yoga through YogaSkills.com. "You don't respond in an inappropriate way. By slowing your breathing down, you can slow your heart rate. By slowing your heart rate, you calm yourself down. Then, you can make better decisions."

In small, specialized studios and large, comprehensive health clubs, yoga practitioners are also reaping the other benefits of the ancient art. Particularly, they say yoga helps them understand their bodies, improve their confidence and combat long-term health problems.

Learning To Understand Their Bodies
"We use a three-foot skeleton in our classes," says Paula Kout, director of White Iris Yoga in Evanston, Ill. "We show you what the skeleton looks like, so that people are grounded in the actual reality of their body. This becomes a tool you use ideally all the time. You think, how am I going to get out of the car? How am I going to lift my groceries? What muscles am I going to use?"

By focusing on understanding their bodies, yoga practitioners learn to stop measuring themselves in the mirror "by these very bizarre standards of airbrushed bodies," says Kout. As students practice new positions -- and learn their bodies' abilities and limitations -- they develop "more of a friendly than adversarial relationship with their bodies."

Hotep, who has led yoga classes in Chicago for 24 years, says yoga "has reversed my aging process. I'm 46 and I can still do things like when I was 28. I have no aches and pains. I have a lot of energy. On days I do yoga, I can run farther than on days I don't."

Improving Confidence
Many yoga students haven't stretched in years and initially find the positions difficult. But with practice and encouragement, over time it becomes easier to hold even difficult poses, such as the "spider." And as their bodies change, so do their minds. For some people the results are astounding.

"I had a woman who came to me when she was in her 50s," says Kout. "We jokingly called her the Tin Man. Every joint in her body was stiff, and she was filled with fear. Everything we did, she said, 'I can't do that; it hurts.' Like water wearing away a stone, though, she came to class week after week, year after year. Her body began to change, and her clothing fit differently. People began to notice the change. She had a much-improved posture.

"At 61 she got married for the first time," says Kout. "Not only did she change her body, but she opened herself up emotionally. She's now happily married and very attractive and limber. As she was getting older, she was actually getting younger. Miracles do happen."

Combatting Long-Term Health Problems
Almost all yoga practitioners notice health improvements. Pregnant women, in particular, benefit from the emphasis on breathing and muscular control. People with heart problems are able to control their blood pressure by learning to control their breathing. Others find that they don't sprain their ankles or bang their elbows as frequently. Some find relief from digestive problems.

O'Bannon, the product manager who takes yoga classes at the Chicago Bally's, has suffered from asthma for years. "Yoga has really helped me a lot," she says. "It helps you take in more air and relax. I don't have strong attacks anymore. I attribute that to my yoga. I don't use my inhaler as often on days I do yoga."

In the last 10 years, yoga groups for people with HIV have become common. Studies have shown that yoga practitioners are less likely to develop full-blown AIDS, says Hotep.

"One of the things about an illness is that you feel out of control," says Kout. "Yoga helps you bring the locus of control back into yourself. There's less of a victim mentality. You don't need someone to do something for you when you're in pain. You know you can do it yourself. I've seen people heal old injuries. I've seen people rehabilitate things like breaks and strains. I've seen people able to sleep because they're breathing more correctly."

While yoga doesn't usually burn as many calories as some high-impact workouts, the discipline -- by stressing self-knowledge, control and nutrition -- can play an active role in helping people lose weight. Hotep says he recently ran into a former pupil who had lost 35 pounds while taking yoga. The student said she also no longer suffers from stomach pains that had stumped her doctors and plagued her for years.

Advice For Beginners
Most teachers believe yoga has its roots in the Hindu faith. Some newcomers, aware of the spiritual writings of some yoga masters, are fearful that taking yoga may conflict with their own religious beliefs. Both Hotep and Kout, however, say yoga is compatible with virtually all faiths and philosophies. "It's not a religion," says Kout. "It's a complement to anything else that you may do in your life." While some advanced classes may cover meditation and philosophy, beginning classes usually focus on breathing and stretching.

Over yoga's 5,000-year history, many different styles have evolved. Both Hotep and Kout say beginners don't need to worry too much about selecting a particular style. "It's like going to a therapist," says Kout. "Either you resonate with that particular person or you don't. Just trust your own feelings."

Hotep advises beginners to make sure the teacher works with your limitations. "I don't have a teaching style," says Hotep. "I conform my style to my students."

Yoga need not be expensive. Fees usually range from about $8 per class at larger health clubs to $20 at some specialized studios. Both teachers recommend attending at least one class per week to make sure you aren't developing bad habits. Students usually wear comfortable, loose-fitting clothing. Most practitioners purchase inexpensive mats that are available through health clubs and studios.

Even though yoga is an improbably complex art -- with as many as 840,000 possible positions -- students don't need to abandon all their other commitments before they get started. "It's like playing the piano," says Kout. "First you learn scales. You have to practice and build incrementally so you can learn more. Five minutes a day every day will mean more than spending huge blocks of time every once in a while."