For this study, doctors assigned 195 people with mild-to-moderate Parkinson’s disease to one of three groups: The first took tai chi classes, the second exercised with weights, and the third was assigned to a program of seated stretching. All the groups met for 60-minute sessions twice each week.

After six months, people who had been taking tai chi were able to lean farther forward or backward without stumbling or falling compared to those who had been doing resistance training or stretching. They were also better able to smoothly direct their movements. And they were able to take longer strides than people in the other two groups.

Like resistance training, tai chi helped people walk more swiftly, get up from a chair more quickly, and increased leg strength.

Perhaps the most impressive benefit of tai chi, however, was related to falls. Falls are common in people with Parkinson’s, and they can cause serious injuries, including fractures and concussions. Studies show falls are the main cause of hospitalizations in Parkinson’s patients. People in the tai chi group reported half the number of falls compared to those who were taking resistance training and two-thirds fewer falls than people who were doing light stretching exercises.

See this article from the National Institute of Health:

http://www.ninds.nih.gov/news_and_events/news_articles/Li_TaiChi_and_PD.htm