• VAS, SF-36, WOMAC, and Activity Index questionnaires [ Time Frame: Week 52 ] [ Designated as safety issue: No ]
  
• Weight-bearing anterior-posterior (AP) and lateral x-rays of the knee [ Time Frame: Week 52 ] [ Designated as safety issue: No ]
  
• MRI imaging of the knee [ Time Frame: Week 52 ] [ Designated as safety issue: No ]
  
• Measurements of gait during level walking and stair climbing [ Time Frame: Week 52 ] [ Designated as safety issue: No ]
  

• Change in consumption of analgesics, reflecting the level of joint pain [ Time Frame: Week 52 ] [ Designated as safety issue: No ]
  

Traditional, conservative medical treatment of osteoarthritis has been directed at improving functional status through reducing joint pain and inflammation and maintaining or restoring joint function. Exercise is an adjunct therapy in the clinical management of patients with osteoarthritis of the knee. However, it is not uniformly accepted. The central hypothesis of this work is that the Surgeon General's exercise guidelines can be successfully implemented as an effective nonsurgical option for treatment of patients with early stages of knee osteoarthritis.

Patients with knee osteoarthritis will be randomized into a control group, a walking exercise group, and a stationary cycling exercise group. The individuals in the exercise groups will be required to exercise three times per week for one year using emerging public health recommendations for aerobic exercise in the adult and aging population. Patient outcome will be assessed using objective gait analysis measurements, knee radiographs to quantify joint space narrowing, magnetic resonance imaging, a general health questionnaire (SF-36), a disease/site specific questionnaire (WOMAC), and a visual-analog pain scale. All subjects will be studied at 0 and 52 weeks.