Osteoarthritis of the knee (KOA) is the most common cause of disability in older adults. Osteoarthritis involves a loss of cartilage, which acts like a cushion between the bones as well as changes in the bones of joints. Once the joint cartilage is gone, the body does not produce new cartilage. Joint damage can contribute to pain. Currently, treatment for pain associated with knee osteoarthritis includes exercise. However, exercise at a medium- to high-intensity level can be problematic for people with knee pain. Because exercise is a common treatment for knee pain but many people experience pain during exercise, researchers hope to find a safer and more effective exercise method to strengthen the muscles around the knee.