The primary objective is to evaluate water based treadmill exercise, land based treadmill exercise, and upright cycling in meeting American College of Sports Medicine exercise goals for moderate exercise.

The secondary objective is to compare exercise tolerance for water based treadmill, land based treadmill, and upright cycling in meeting American College of Sports Medicine exercise goals for moderate exercise.

The tertiary objective is to evaluate quality of life improvements for water based treadmill exercise, land based treadmill exercise, and upright cycling.

Osteoarthritis is the most common joint disorder in the United States, affecting approximately 26.9 million adults greater than 25 years of age. This disorder can be very debilitating: more than 40% of adults with doctor diagnosed arthritis have reported that joint symptoms cause them to modify their activities. Risk of disability (defined as needing help walking or climbing stairs) associated with osteoarthritis is considered equivalent to cardiovascular disease and is greater than any other medical condition in elderly patients [13]. Persons with disability associated with osteoarthritis have a substantially worse health-related quality of life, in large part due to their inability to exercise.

Exercise has been shown to help maintain function in knee osteoarthritis [5]. Aerobic walking and quadriceps strengthening exercises ([18];[7]) and resistance training [15] have demonstrated that exercise can potentially improve pain and function in individuals with knee osteoarthritis. Likewise, a Cochrane review on aquatic exercise provided gold level evidence that aquatic exercise probably reduces pain and increases function over 3 months; but, it stated clearly that more research was needed to understand which type of aquatic exercise, how often, and for how long might be beneficial [2]. The American College of Sports Medicine (ACSM) recommendations for healthy adults recommend moderate-intensity aerobic exercise (endurance) physical activity for a minimum of 30 minutes, 5 days per week or vigorous-intensity aerobic physical activity for a minimum of 20 minutes, 3 days per week in all healthy adults aged 18 to 65 to promote and maintain health [9]. The best method of reaching current ACSM goals in patients with knee osteoarthritis is not known, as impact-related exercise certainly demands healthy joints and many patients with knee osteoarthritis do not tolerate this form of exercise.

In counseling patients with knee osteoarthritis, the question remains: how best to exercise to reach the ACSM goals for exercise. This study will compare water-based and land-based treadmill exercise and upright cycling in meeting ACSM exercise goals for moderate exercise.

Interested subjects will undergo knee radiographs to confirm presence and degree of knee osteoarthritis. Eligible participants will then be randomized into one of the three exercise cohorts. During each session, participants will complete between 10 to 45 minutes of exercise, with a goal of achieving 30 minutes of moderate aerobic exercise. All subjects will only participate in routine activities for the 8 week study period outside of the study protocol (no strength training, cardio training, etc.). Health status measurement questionnaires (WOMAC, KOOS, and SF12) will be completed at the time of randomization and at the conclusion of each week of exercise for a total of 9 times.

Inclusion Criteria:

• Ages 30-60
• Knee pain
• Radiographically confirmed knee osteoarthritis

Exclusion Criteria:

• Medical conditions contraindicating moderate aerobic exercise as determined through prescreening questions, ie: heart condition, asthma, history of stroke.
• Inability to exercise via treadmill or exercise cycle
• Contraindication to radiography
• Pregnancy
• History of recent joint injection (steroid, synvisc, etc.) within 6 weeks of study
• History of previous joint arthroplasty
• History of inflammatory joint disease
• Inability to sign informed consent

Subjects for this study will be recruited from Penn State Milton S. Hershey Medical Center and surrounding communities via internal and external advertisements.