Keeping individuals with knee osteoarthritis physically active is critically important. Exercise is effective at reducing pain while improving physical function. However some exercises can overload the knee, and as a result, worsen knee pain and health of the knee joint. Yoga offers a foundation of static postures that improve muscle strength and joint flexibility. Using sophisticated technology that allows us to calculate the loads inside the knee, the investigators have selected yoga exercises that do not overload the knee joint. The investigators have designed a yoga exercise class that is ideal for people with knee osteoarthritis. The purpose of the study is to investigate whether these yoga exercises increase muscle strength and reduce knee pain in women with knee osteoarthritis. In addition, the investigators aim to show that these yoga exercises will also improve knee loads during activities, mobility and heart health. The investigators will ask 50 women with knee osteoarthritis to participate in a 12 week yoga exercise intervention, that requires attendance to 3 classes each week. The investigators will test strength of the leg muscles, pain, knee joint loads, mobility and cardiovascular health before and after the 12 week yoga exercise intervention.