The study objectives are to compare the immediate effect of intermittent vs. continuous walking on clinical and mechanistic pain profiles in persons with knee osteoarthritis (OA). The investigators hypothesize that continuous walking will result in greater increases in clinical pain and mechanistic pain sensitivity than intermittent walking. Physical activity (PA) has been recommended as the first-line management strategy for people with chronic knee pain. Walking is an accessible, low-cost, joint-friendly form of PA and is widely advocated for older adults with knee complaints. However, movement-evoked pain is a commonly cited barrier for PA engagement. On one hand, a bout of PA may produce short-term analgesia and reduce pain. On the other hand, excessive or prolonged PA may exacerbate symptoms and lead to avoidance/fear of subsequent PA. Besides the total PA volume, how it is accumulated could also impact joint health. It is biomechanically plausible that shorter and frequent activities are more beneficial to articular tissues than longer and infrequent activities. Compared to intermittent loading, prolonged continuous loading had a detrimental effect on the biomechanical functions of articular cartilage in a bovine model. Findings of this study will provide insight on the relations between patterns of PA and pain profiles.
The goal of this single-blind, cross-over clinical trial is to compare the immediate effect of intermittent vs. continuous walking on clinical and mechanistic pain profiles in persons with knee osteoarthritis (OA). In this cross-over trial, participants will perform two types of walking on a treadmill. Intermittent walking will involve 3 blocks of 10 minutes with 2 blocks of 5-minute rest (sitting on a chair) in-between. Continuous walking will involve resting for 10 minutes (sitting in a chair) before walking on the treadmill for 1 continuous block of 30 minutes.