Osteoarthritis is one of the most common form of chronic diseases in the adult population, and approximately 800 000 people in Sweden (population of approximately 9 million people) suffer from this disease, which causes joint pain, stiffness, swelling, loss of function and sick leave. Studies from Sweden, United Kingdom (UK) and USA show that costs for osteoarthritis are about 1-2.5 % of GDP. With increasing life expectancies and the general decrease in physical activity in western industrialized countries, it is expected that more people will suffer from this disease. In a recent international literature review of clinical studies on the effectiveness of exercise therapy, the authors concluded that there is some evidence that therapeutic exercise is effective reducing knee pain and improving activities of daily living. In a compilation of scientific studies by the Swedish Council on Technology Assessment in Health Care (SBU), it was concluded that strength and flexibility exercises resulted in positive short-term effects compared to information only. However, there is currently no scientific study that has evaluated dose-response effects of exercise therapy. To improve life quality for individuals with osteoarthritis and the use of exercise therapy in primary and secondary health care settings, research on dose response effects in patients with osteoarthritis is important. This view is supported by various systematic reviews including the report from Swedish Council on Health Technology Assessment (SBU) latest compilation.