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Knee osteoarthritis is associated with chronic pain, knee stiffness, decreased function, and reduced quality of life. The preferred treatment is exercise therapy, including medical exercise therapy, which consists of self-paced exercises set by the patient and a physiotherapist. The type, intensity, duration, and frequency of these exercises can be categorized as low- or high-dose. Studies of other patient populations with conditions including diabetes and cardiovascular disease have demonstrated positive dose-response relationships to exercise, but this is not true of musculoskeletal pain.
Using a superiority design, researchers from the Karolinska Institutet, Holten Institute, Sweden, and Norwegian University of Science and Technology, and Rosenborg Fysioterapiklinikk, Norway, randomly assigned 189 persons with knee osteoarthritis with pain and decreased function to either low- or high-dose exercise therapy to compare exercise dose response with regard to knee function, pain and quality of life. The researchers hypothesized that exercise at a higher dose would produce superior outcomes in this patient population. Results were measured using the Knee Injury and Osteoarthritis Outcome Score (KOOS) biweekly for 3 months and then again at 6 and 12 months. At all follow-up periods, KOOS scores improved in both groups, findings that did not support the authors’ hypothesis. The only differences favoring high-dose exercise were in the domain of knee function during sports and recreation at the end of treatment and 6 months after the intervention and in the quality-of-life domain at 6 months. The authors note that high-dose treatment could be preferable to low-dose treatment in the long run for people who lead active lives. However, adherence could be an issue, as those in the low-dose group had nearly perfect adherence to the intervention, while the high-dose participants had a higher drop-out rate.