A commonly administered conservative non-pharmacological treatment for OA is exercise, with beneficial effects in terms of reduced pain and disability.

While the link between exercise and reduced disability is mediated by e.g. increased muscle strength and endurance, the analgesic mechanisms related to exercise are unexplored. knee OA patients have both peripheral and central sensitization of pain mechanisms resulting in hyperalgesia. Thus, targeted pain treatment in these patients may focus on both peripheral and central mechanisms but it unknown if exercise affects either of these mechanisms.

It is hypothesized that in knee OA patients exercise reduces the pain sensitivity

Inclusion Criteria:

• Age above 40 years
• Clinical diagnosis of tibiofemoral osteoarthritis
• Radiographic verification of diagnosis (Kellgren&Lawrence 2 or 3)
• Ability to participate in examinations
• Ability to participate in exercise sessions
• 20≤ Body Mass Index (BMI) ≤35 kg/m2
• Ability to comply with rules about concomitant medication and therapy
• Speak, read and write Danish

Exclusion Criteria:

• Participation in exercise training for the knee osteoarthritis within 3 months of enrollment
• Counterindications for exercise
• Pregnant or breastfeeding
• Current or previous autoimmune disease
• History of surgical joint replacement in the lower limbs
• Planned surgery
• Current or previous diagnosis or signs of cardiovascular disease
• Neurological disorders
• Alcohol or drug abuse
• Diabetes
• Psychiatric disorders
• Regional pain syndromes
• Regional pain caused by lumbar or cervical nerve root compression
• Counterindications to MR scan
• Counterindications to MR contrast