Tai chi is good, but how good?

A review of medical studies gave the thumbs-up on Monday to tai chi as a way of preventing falls and improving mental health in the elderly, but does not confirm other claims made for the Chinese martial art.

British and South Korean researchers looked at 35 assessments of tai chi found in English-language, Chinese and Korean databases.

There was "convincingly positive" evidence that, among the elderly, practicing tai chi helped sense of balance and boosted psychological well-being.

However, the sport "seems to be ineffective" for treating the symptoms of cancer and rheumatoid arthritis, the authors say.

The evidence was contradictory as to whether tai chi improved high blood pressure, type 2 diabetes, cardiovascular disease, muscle strength, osteoporosis and other conditions.

Many studies were flawed because they had a poor design or were at high risk of bias. For instance, they enrolled only small numbers of volunteers or lacked an adequate "control" group to ensure a fair comparison.

The overview was conducted by Lee Myeong-soo of the Korea Institute of Oriental Medicine in Daejeon, and Edzard Ernst of the University of Exeter, southwestern England.

It appears in the British Journal of Sports Medicine, published by the British Medical Association.

Tai chi entails regular practice of deep breathing and relaxation techniques, combined with slow and gentle movements.

DPA-Reuters