Unravelling the Acute Effects of Exercise on Pain in Knee Osteoarthritis: What Can We Learn to Inform Rehabilitation?

Abstract

Knee osteoarthritis (OA) is a prevalent, disabling condition characterised by pain and functional limitations. Although exercise is a recommended first-line treatment, it remains underutilised. Individual variability in exercise-induced hypoalgesia (EIH) is important to consider to optimise exercise interventions. This thesis explored sources of variability in EIH and two interventions to enhance EIH in people with knee OA. A large cross-sectional study found that age was positively associated with EIH, while anxiety and negative pain expectations were linked to reduced EIH. However, these variables accounted for less than 10% of the variance, underscoring the need to identify additional factors. A randomised controlled trial examined whether positive pre-exercise education can increase EIH. While the intervention increased participants’ beliefs that exercise can reduce pain it did not increase EIH compared to the control condition. Finally, a double-blind randomised crossover trial, examined whether a single session of transcranial direct current stimulation (tDCS) could enhance EIH, with no significant differences observed compared to sham. Overall, this thesis provides a deeper understanding of EIH variability in knee OA, highlights important future research directions and underscores the need for personalised exercise approaches that consider psychological and physiological factors to optimise pain relief in knee OA.