In 12th century China, a Taoist monk known as Chang San-Feng is said to have studied the physical movements of five animals and concluded that two - the snake and the crane - were best-suited to overpower opponents who were fierce and tenacious.
From that ancient observation, the slow, graceful movements of tai chi were born.
Today, with the art and exercise of tai chi growing in popularity across the United States, scientists have found that older adults who practice this martial art strengthen themselves against an opponent as stubborn as any - the tiny chickenpox virus, which can cause a painful and often persistent nerve inflammation called shingles.
The new study, published in the Journal of the American Geriatric Society, is the first - and most rigorous - of a welter of rigorous new studies designed to probe the health effects of tai chi.
Also in the works are five federally funded studies examining whether regular practice can help patients contending with heart disease, osteoarthritis and cancer fight off threats such as depression, infection and the pain of joint inflammation. Other studies are probing whether tai chi can improve balance and reduce falls among the elderly, and improve the well-being of patients with HIV.
"Tai chi is clearly an exercise program, but it has something more," says Andrew Monjan, chief of the National Institute on Aging's neurobiology of aging branch. "It seems to be somewhat more effective than simple exercise, and more effective than simple stress reduction." And older adults enjoy it, he says, making it a therapy patients will stick to.
For healthy older adults, the study demonstrated a striking immunity- boosting effect. After 16 weeks of tai chi classes - even before they received chickenpox vaccine - subjects practicing tai chi showed immunity levels to chickenpox (and hence to shingles) that were comparable to those of 30- and 40-year-olds who got the vaccine. After the tai chi practitioners got the dose, their immune response surged by 40 percent.
Compared with a similar group of non-tai chi-practicing older adults who received a shot of vaccine and a 16-week health-education program, those who practiced tai chi during the same period built stronger immunity to chickenpox and to shingles. They also showed significant improvements in measures of physical functioning, vitality and mental health.
"It looks like a strong phenomenon, a fairly robust effect," Monjan says. Tai chi's combination of slow, steady movements, rhythmic breathing and meditation appears to offer a unique mix of benefits, Monjan says. It builds aerobic conditioning. It relaxes the body's response to stress, which tends to intensify as people age. And it increases the flow of blood and oxygen to the brain.
But which of those effects produces the powerful immunity-building responses seen in the most recent study - or whether that effect is the product of some synergy among those effects - remains a mystery, he adds. Future studies may seek to answer that question, Monjan says.
Dr. Michael R. Irwin, of the University of California, Los Angeles' Cousins Center for Psychoneuroimmunology, directed the study, recruiting 112 healthy adults in the Los Angeles and San Diego areas, with an average age of 70. All had contracted chickenpox at an earlier age, so had some immunity to a recurrence of that disease. But as people age, they become more vulnerable to the virus that is left behind by a case of chickenpox - the varicella virus, which causes shingles in one of five adults who have had chickenpox. The virus lies dormant in its host until a flagging immune system allows it to reawaken and inflame nerves.
Generally, a dose of chickenpox vaccine will boost immunity to shingles, but in older adults, that boost can be less robust than among younger patients.
To test whether the practice of tai chi had an effect on immunity to varicella (and hence, to herpes zoster), Irwin divided the group of healthy adults in half. Although all got a dose of varicella vaccine, half also received 120 minutes a week of tai chi for 16 weeks, while the other half got 120 minutes per week of class time on a variety of health-related topics.
Even before the vaccine was administered after 16 weeks, the stronger immune response of the tai chi group, as compared with that of the group receiving general health instruction, was striking, Irwin said.
Effectively, the tai chi group looked as if it had already had the vaccine. After members of both groups got a dose of vaccine, the tai chi group's immune response picked up more steam and was almost twice as strong as that of the non-tai chi group at the end of the study.