Practicing tai chi, a gentle exercise discipline developed 2,000 years ago in China, may boost your immune system. A study recently published in the Journal of the American Geriatrics Society (2007, vol. 55, no. 4) found that patients who practiced tai chi had a significantly higher immune response to the hardy chickenpox virus, varicella, than nonpractitioners.

Researchers recruited 112 healthy adults, ages 59 to 86, and assigned them to either a tai chi or health education group for 25 weeks. After 16 weeks of treatment, subjects received the chickenpox vaccination. At the end of the study, tai chi participants had almost twice the levels of cellular immunity to the virus as the other group. Scientists found elevated immune responses in the tai chi group even before administering the vaccine. Postvaccine tests showed additional benefits.

Even better, at the end of the study, the tai chi group also reported decreased bodily pain and improved mental health, physical functioning, and vitality.

This research adds credence to the growing body of studies documenting the health benefits of meditative forms of exercise. Researchers at Washington State University enrolled breast cancer survivors receiving hormonal therapy in Iyengar yoga classes. After eight weeks, subjects reported less stress and better quality of life; tests also indicated improved immune function. Results were reported in April at the annual meeting of the American Physiological Society.