The gentle movements and deep breathing techniques of tai chi, tones muscles and boost mood says, Chenchen Wang, MD, author of a new study from Tufts University in Boston. For the 34% of women over 50 with knee osteoarthritis, tai chi offers powerful relief. Scientists assigned 204 suffers to either a tai chi or physical therapy twice weekly for 12 weeks. The tai chi group experienced a whopping 66% drop and pain and stiffness, plus a 28 % drop in depression. Their results were 10% better than the physical therapy group.