Often called "moving meditation" or "the art of creating energy," tai chi began as a martial art in China about 2,000 years ago. Over the past century, it has become extremely popular as an exercise for older adults and is practiced by millions of Chinese each morning in parks across the United States.

But tai chi's graceful movements are so slow and deliberate that researchers from Johns Hopkins University in Baltimore assumed it wouldn't have much impact on blood pressure. So in a study of the effect of moderate exercise on hypertension, they assigned the control group to learn tai chi. To their surprise, tai chi appeared to lower blood pressure in older adults nearly as much as moderate-intensity aerobic exercise.

"We were expecting to see significant changes in the aerobic exercise group and minimal changes in the tai chi group," assistant professor of medicine Deborah R. Young reported at a recent American Heart Association conference. After 12 weeks, however, the tai chi group's average systolic blood pressure had fallen by 7 millimeters of mercury, compared with an average of 8.4 millimeters of mercury in the aerobic exercise group.

The researchers studied 62 sedentary men and women, aged 60 and older, whose systolic blood pressure was in the "high normal" to "mild hypertension" range. Half the group was randomly assigned to a 12-week program of brisk walking and low-impact aerobics. The other half, which was the "control" group, learned tai chi. Both groups exercised four times a week for 30 minutes per session. And in both groups, blood pressure began to drop after just six weeks of exercise. "Clearly, in future studies we need a true 'no exercise' control group," says Young. "This study was a pilot, and more research is needed."

Extensive evidence indicates that regular aerobic exercise can decrease resting blood pressure by approximately 10 millimeters of mercury, and that mild exercise may reduce blood pressure just as much as or even more than strenuous activities, such as jogging. Mind-body exercises such as tai chi may provide an added boost to both physical and mental health, which is why the Eastern healing art is increasingly being studied by Western medical practitioners.

A growing body of research suggests that practicing tai chi has many benefits for seniors, including a reduced risk of falling and a significant improvement in quality of life. Tai chi is now being used in some cardiac rehabilitation programs and by people with diseases such as fibromyalgia, arthritis and multiple sclerosis, notes Harvey Kurland, an exercise physiologist from Riverside, Calif., who has been studying and teaching tai chi for over 30 years. Kurland teaches for the University of California Riverside. His research, published in the journal Sports Medicine, Training and Rehabilitation, found tai chi to be a low-intensity aerobic exercise equivalent to walking at a three-mile-per-hour pace.

"In Chinese medicine, tai chi is used as a way to relax the body and let the chi [vital energy] flow throughout the body," says Kurland, who credits the 1993 PBS-TV series "Healing and the Mind" with sparking an explosion of American interest in tai chi. Physical activity is considered an essential component of health by the Chinese, who believe that without daily movement the body's chi can become stagnant, which can lead to illness. The existence of this life force has never been scientifically proven by Western standards.

Tai chi can strengthen the legs and arms, improve balance and flexibility, Kurland says. "But the stress reduction benefit is probably the best thing tai chi does for health," he notes. "Stress is the number one health problem in America, with an estimated 60 to 70 percent of all visits to physicians due to stress-related illness. A daily practice that can relieve stress will improve health."