We conducted a randomized, controlled trial to determine whether a tailored tai chi
program could improve postural control in patients with idiopathic Parkinson’s disease. We randomly assigned 195 patients with stage 1 to 4 disease on the Hoehn and
Yahr staging scale (which ranges from 1 to 5, with higher stages indicating more
severe disease) to one of three groups: tai chi, resistance training, or stretching.