Exercise Therapy for Osteoarthritis Pain: How Does it Work?

International guidelines recommend exercise as the first choice treatment for knee osteoarthritis (KOA). Muscle strengthening training (MST) and behavioural graded activity (BGA) show comparable effects on KOA pain, but the mechanisms of action are unclear. Understanding these mechanisms is necessary to tailor exercise therapy towards specific mediators and thereby optimize treatment effects. Based on previous studies, both exercise-induced anti-inflammation and endogenous analgesia are promising pathways for pain reduction after exercise therapy. This study aims to examine (anti)-inflammation and endogenous analgesia as mediators for the effect of MST and/or BGA on pain in patients with KOA. Therefore, a 3-arm randomized clinical trial is established: 12 weeks of muscle strengthening training, behavioural graded activity or control. Mediator analysis will be performed. Unravelling the mechanisms of action of exercise therapy in KOA will not only be extremely valuable for researchers, but also for exercise immunology and pain scientists. The results of this research will also find their way into clinical practice: thanks to the current project, tailoring exercise therapy programs towards specific mechanistic factors and thereby optimizing treatment effects will be at the horizon for patients suffering from KOA.