EVALUATION COMMITTEE

The Faculty Council has appointed the following adjudication committee to evaluate the thesis and the associated lecture: 

• Prof. Inger Mechlenburg, Aarhus University, Denmark
• Prof. David Hunter, The University of Sydney, Australia
• Dr. Andrew James Thomas Stevenson, Aalborg Universitet, Denmark (Chairman).

Moderator: Prof. Michael Skovdal Rathleff, Health Science and Technology, Aalborg University

ABSTRACT

Physical activity (PA) is the first-line management for knee osteoarthritis (OA) and confers many health benefits, but excessive or insufficient amount of PA may result in symptom exacerbation. PA-induced pain flare or relief is poorly understood. There may be an optimal range of PA “dose” and “delivery” method that could minimize its side effect of symptom aggravation. In this doctoral work, we will study the relationship between PA and pain in the context of knee OA, employing three study designs and methodologies. First, we aimed to determine objectively measured physical activity metrics that prevent subsequent symptomatic worsening in a longitudinal observational cohort. Second, we aimed to examine the immediate effect of intermittent vs. continuous walking on pain intensity and pain sensitivity in the laboratory using a cross-over randomized controlled trial design. Third, we aimed to explore the within-person temporal patterns of physical activity and pain in free-living environment, using ecological momentary assessment.

Accelerometry-measured physical activity at baseline was not associated with knee OA pain experience trajectory over 4 years. However, baseline widespread pain, knee stiffness, back pain, hip pain, ankle pain, obesity, depressive symptoms, more advanced radiographic disease, and analgesic use were each associated with unfavorable pain experience trajectories. Compared to continuous walking, intermittent walking resulted in less pain flares and reduced temporal summation of pain, and possibly facilitated conditioned pain modulation. Pain intensity was highly variable in some participants. Higher moderate-to-vigorous intensity PA minutes was associated with greater immediate subsequent knee pain intensity. There were no associations between light-intensity PA and knee pain.

For individuals with chronic painful knees, walking with frequent breaks and at a light intensity may help mitigate the adverse effects of pain flares and harness the analgesic effect of physical activity.