Tai chi looks so easy. It's hard to imagine that slow, circular movements of the arms can really be exercise. But Allison Barnett, an Illinois tai chi instructor, said the controlled movements provide healthy benefits for both mind and body.

Tai chi is a peaceful alternative to the wild antics of aerobics and is attracting new followers each day. Barnett and her husband, Herb, run Barnett Martial Arts Association, which supplies tai chi instructors for colleges, community centers and other groups throughout the Illinois suburbs.

"We have seen an explosion of interest in the last couple of years," Barnett said. "We are running 20 to 25 classes at all times during the year."

Barnett's personal story is an example of how tai chi can change lives:

"I came to tai chi as a classic stress cadet," said Barnett, whose high-stress job was causing her to suffer a spastic colon and other health problems. "I tried conventional Western medicine and ended up walking around in a daze from the medication. Then, one day, I walked into a tai chi class, and it changed my life. Just learning the breathing alone helped untie all of the knots in my colon."

Barnett saw her health steadily improve as she mastered the techniques. The class also provided her an introduction to the instructor, who later became her husband. Barnett doesn't guarantee the romantic benefits she experienced with tai chi, but she does say the regimen will improve physical and mental health.

"Tai chi looks deceptively simple," Barnett said. "You work in a low stance with your knees bent. The important thing to learn is to breathe from your center of gravity, which is known as tan tien. It is a point about two inches below the navel and one inch inside the body. We learn to breathe to that point instead of the rib cage."

Tai chi also requires the participants to breathe very slowly.

"This aids in circulation and is more nourishing to the inner organs. It will also lower blood pressure," Barnett said.

In addition to breathing, participants also concentrate on moving from this center of gravity, tan tien. A specific pattern of movement is memorized and repeated during tai chi. These patterns have been used for centuries and are believed to have been founded around 1200 in China.

There are four basic styles of movement, Barnett said. The most popular is the yang style.

"There are many variations, but it is all based on slow, large, circular movements," she said.

Other styles include the chen, we and sun. Each pattern varies in speed, shape and direction of movement.

Barnett teaches a short form of the yang style to her beginners' classes. This abbreviated series contains 12 postures. The full form of 108 postures takes between two and three years to master.

"It is a low-impact exercise because it is slow, even pressure on the muscle and joint. In aerobic exercise, you might move your arms up and down. In isometric exercise, the arm is just held straight out."

The isometric pressure on the muscle and joints strengthens without the pounding of aerobic exercise. Tai chi also improves flexibility and balance.

"People are surprised to find their legs shaking and sweat on their brow during tai chi. Make no mistake — this is a workout," Barnett said.

This gentle method of exercise is very popular with seniors who may find other forms of exercise too exhausting or jarring.

The meditative and breathing aspects of tai chi make it an excellent way to fight stress, which is one of the reasons Jeff Zwier turned to tai chi.

"I needed something I could do by myself at home or in a hotel room that didn't need any special equipment, and tai chi offered that," said Zwier, who feels plenty of stress on the job as owner of Innovatia Performance and Learning, a training and consulting firm. "The movements in tai chi are just sophisticated enough that you can't think about anything else. You go into a bubble of thinking about yourself…and you also get one heck of a workout."

The recent popularity of tai chi has brought some imitators. Barnett cautioned people interested in pursuing tai chi to check on the qualifications of the instructor.

"I've seen some people call kick-boxing classes tai chi. There are lots of fake versions out there," she said.