The Effect of Different Exercise Training Programs on Muscle Oxygenation in Individuals With Knee Osteoarthritis

Knee osteoarthritis can cause pain, reduced muscle strength, and difficulty with daily activities. Exercise is commonly used to manage knee osteoarthritis, but the effects of different exercise programs on muscle oxygenation are not fully understood. This study will compare three 6-week exercise programs in adults with knee osteoarthritis: aerobic exercise on a recumbent bicycle, lower-limb strengthening exercise, and a program combining aerobic and strengthening exercise. Participants will be randomly assigned to one of the three groups. Each group will attend three supervised exercise sessions weekly for 6 weeks. All participants will also receive a home stretching program. Participants will be assessed before the program, at weeks 3 and 6, and again at week 10, after a 4-week period without supervised exercise. The study will examine whether the exercise programs improve muscle oxygenation and whether changes in muscle oxygenation are associated with changes in muscle strength, pain, and physical function. The investigators expect muscle oxygenation to improve after the exercise programs and expect these changes to be associated with improvements in clinical measures.

Inclusion Criteria: * Age 45 to 65 years. * Body mass index (BMI) below 30 kg/m². * Physician-diagnosed knee osteoarthritis according to the American College of Rheumatology (ACR) criteria. * Bilateral knee osteoarthritis of Kellgren-Lawrence grade 2 or 3. * Willingness to participate and provide informed consent. Exclusion Criteria: * Orthopedic or rheumatologic disease of the lower extremities, or arterial or venous disease. * Uncontrolled hypertension, pulmonary disease, or diabetes. * Neurological disease. * Learning or cognitive impairment that may prevent participation. * Knee extension deficit. * Physical activity level above 600 MET-minutes/week, assessed using the International Physical Activity Questionnaire-Short Form (IPAQ-SF). * Treatment for knee osteoarthritis within the previous 6 months, including physical therapy or injection.