Patients are being assessed by blinded assessor at inclusion, at end of intervention (3 mo), and at six and 12 mo after end of treatment. We plan to include a total of 200 subjects from primary health care settings, two in Norway and two in Sweden, with radiographic-verified knee OA with knee pain and decreased function. The patients have to be within the 45 to 85 age group. Patients are excluded if they have been scheduled for knee surgery or have some other form of illness/disease that limits the exercise tolerance (e.g. heart disease or systemic/metabolic diseases or chronic obstructive airways disease). A major goal is to grade exercises so that they are performed pain-free or close to pain-free in both intervention groups. The principle of deloading is used to meet this goal using a high number of repetitions in sets as pain modulation. The results from this study will give new information about the effectiveness of graded exercise therapy in patients with knee OA, and new knowledge if outcome can be related to the exercise dosage performed.