Researchers from the USA have found that knee osteoarthritis (OA) patients who practise tai chi show improved physical functioning and experience less pain. Forty individuals (mean age 65) with tibiofemoral OA were randomly assigned to 60 minutes of tai chi or a control intervention (wellness education and stretching) twice weekly for 12 weeks. Each tai chi session included: 10 minutes of self-massage with a review of tai chi principles, 30 minutes of tai chi movement (modified Yang style 10 forms), 10 minutes of breathing exercises and 10 minutes of relaxation. After 12 weeks of treatment, patients practicing tai chi exhibited a significant decrease in knee pain compared with those in the control group (a between group difference of -118.80 on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scale). The results also showed significant improvements in physical function, self-efficacy, depression and health status in the tai chi group. (Tai Chi is effective in treating knee osteoarthritis: a randomized controlled trial. Arthritis Rheum. 2009 Nov 15;61(11):1545-53).