Many who practice tai chi find that it also offers a variety of "quality of life" benefits such as improved concentration, an increased sense of well-being, decreased feelings of stress, more energy, improved posture, and better circulation. Derived from the martial arts, this low-intensity, low-impact form of exercise is especially well suited for those recovering from an injury; and because it's a weight-bearing exercise, it's also helpful for preventing the brittle-bone disease, osteoporosis.

To learn the forms, you'll need to attend classes with a tai chi instructor, typically someone who has mastered the Chinese martial arts. No special equipment is necessary, although comfortable loose-fitting clothing and flat shoes or socks are recommended. Some programs encourage participants to wear loose-fitting uniforms similar to those used in other types of martial arts programs.

In each weekly session, you'll be drilled in the positions that make up the various forms. You may find it hard to remember all the movements at first, but like ice skating and bike riding, they become easier with practice. The object is to achieve coordinated, fluid, whole-body movement, even though you may only move one part at a time.

You'll begin by assuming the basic tai chi position: standing with your feet parallel and shoulder-width apart, your knees bent slightly, your head slightly lifted, and your spine straight. Your shoulders should be somewhat rounded and your arms should hang loosely at your sides as you prepare to move into a position.

As you go through each sequence, your knees should remain slightly bent, with all movement originating from the waist. This area of the body located just below the navel is known as your "tantien." In Chinese philosophy, it's considered the center of the body's "chi" or vital energy. By focusing on this center as you practice the deep breathing and slow movements of tai chi, you can expect to experience a heightened awareness of your entire body.

In Bill Moyers' book Healing and the Mind, grand master Ma Yueh Liang describes five principles of successful practice:

First: Calm down. Think of tai chi only.
Second: Eliminate any exertion.
Third: Be consistent in movement and speed.
Fourth: Practice truly and precisely. Study the movements you make.
Fifth: Persevere. Practice for the same amount of time at the same hour each day.

Because you'll be practicing the same movements over and over again, tai chi may seem boring at first. However, for experienced tai chi practitioners, the forms become challenging. Some masters observe that while some people are quick to learn the basic movements of a form, their completed mastery can take a lifetime to achieve. To get the most from tai chi, say the experts, you must endeavor to be introspective, recognizing the stress and tension in your body, and working to release it.

Most people who practice tai chi say they feel they've had a "work out" after an hour-long session, even though they may have never raised a sweat. However, you're unlikely to feel the same type of fatigue you might expect from such exercises as jogging . Instead, you'll probably feel a sense of sustained energy and tension relief. Some practitioners claim that the flowing nature of tai chi so enhances the circulation that they feel warm and invigorated for the rest of the day.

Treatment Time: Classes take 60 minutes. An average tai chi form can be performed in 7 to 10 minutes, once it is mastered.

Treatment Frequency: Tai chi may be performed every day or periodically throughout the week. Daily practice is recommended.

Practitioners of traditional Chinese medicine believe that tai chi improves health by breaking up blockages in the flow of chi, thus reestablishing balance in the body's supply of vital force. Western advocates of the discipline point out a number of less esoteric physical benefits. Especially for older adults, who face a decline in muscle strength, flexibility, and range of motion, tai chi offers all of the following:

• Its slow, deep breathing increases relaxation and concentration.
• Some of the basic movements--putting full weight on the lower leg, alternating from one leg to another, stepping backward and forward and from side to side--help to strengthen muscle and bone, while improving balance and thus preventing falls. (Nearly 30 percent of those over 65 sustain at least one fall. About half of these falls result in serious injuries, mostly fractures of the hip or wrist.)
• Moving the head, eyes, and body together helps to recalibrate the inner ear--the body's balance center.
• Natural extension of the body during tai chi helps encourage correct posture.
• Tai chi's low-intensity movements have an aerobic affect on the heart and vascular system.
• Focused attention on movements encourages mental alertness, while relaxing body and mind.

   Researchers still aren't sure exactly which of these effects is responsible for tai chi's documented ability to reduce heart rate and blood pressure, but studies indicate that it's clearly more effective than ordinary aerobic exercise. One study also found that, among older individuals, mastering tai chi can reduce the risk of falling by nearly 50 percent.

Many tai chi classes are offered at community centers or health clubs. Instructors in these venues are typically experienced enough in the exercises to be able to teach them successfully. However, for training at a more advanced level, you'll need to seek out one of the tai chi masters who generally teach at a specialized school of tai chi. These individuals have practiced the exercises for many years, and must typically receive authorization from their own tai chi master before they begin to teach.

There is no national certifying organization for tai chi instructors, although even instructors at community centers are expected to adhere to a professional set of standards and ethics. When choosing an instructor, you'll therefore need to draw your own conclusions. Make your decision according to the following guidelines:

• Choose an environment that appears clean and safe, and one in which you feel you can learn.
• Ask how long the facility has been operating.
• Make sure the program and format meets your scheduling needs.
• Observe a class before joining or paying for it; watch and listen to the instructor:

   --Does he communicate clearly?

--Does he embody the qualities you wish to learn and emulate?

--Is he mindful of his students' individual abilities?

--Does the class "feel good" to you?

• Ask about the instructor's credentials. Ideally, he should be experienced in all forms of tai chi, from the beginner's level to the advanced martial art form.

When Should Treatment Stop?
The health benefits of tai chi are associated with the exercise itself and won't persist if the practice is stopped. Tai chi is therefore best regarded as a lifelong preventive strategy to improve and maintain health while promoting relaxation and a calm outlook.

However, if for any reason the movements are painful or trigger an old injury, stop exercising and consult your doctor. You may also want to discuss the problem with your instructor to see if the exercise can be modified.

If you are out of shape or have significant health problems, you should check with your doctor before starting the exercises. Be quick to check with your doctor, too, if symptoms of stress, depression, or pain continue to trouble you, or begin to get worse.

If you are using tai chi strictly as a relaxation exercise, you'll still need to see a doctor if you develop any physical problems such as sprains or strains. Although such injuries are highly unlikely, it is always possible that you may trigger an old injury or over-exert your body.