In China, it is believed that tai chi can delay aging and prolong life, increase flexibility, strengthen muscles and tendons, and aid in the treatment of heart disease, high blood pressure, arthritis, digestive disorders, skin diseases, depression, cancer, and many other illnesses. Unfortunately, there hasn't been a good deal of scientific evidence to support all of these claims. In a special study of tai chi called a meta-analysis, where many studies on one subject are reviewed, the author concludes that although there is some evidence to support the positive effects of tai chi on health, fitness, and balance and falling, many of the studies are limited by small numbers of subjects and wide variation in the type and duration of tai chi used. Bearing thesse limitations in mind, here are some of the documented benefits.
Balance and falling
Most of the research on tai chi has been done in older individuals in the area of balance and fall prevention. This area of research is important because fall-related injuries are the leading cause of death from injury and disabilities among older adults. One of the most serious fall injuries is hip fracture; one-half of all older adults hospitalized for hip fracture never regain their former level of function. Because tai chi movements are slow and deliberate with shifts of body weight from one leg to the other in coordination with upper body movements (sometimes with one leg in the air), it challenges balance and many have long assumed it helps improve balance and reduce fall frequency. This assumption has been credited and strongly supported by some research.
One study compared men age 65 and older who had more than 10 years of experience practicing tai chi and no involvement in any other regular sports and physical activity, with similar-aged men who had not practiced tai chi or any other physical activities (they were sedentary). It was found that the men who studied tai chi performed better on tests of balance, flexibility, and cardiovascular function. In another study involving 22 men and women aged 22 to 76 years with mild balance disorders, it was found that eight weeks of tai chi training significantly improved function on a standard balance test (called the Romberg test). http://www.medicinenet.com/tai_chi/page2.htm