The influence of continuous versus interval walking exercise on knee joint loading and pain in patients with knee osteoarthritis

Objective: To evaluate whether knee contact force and knee pain are different between continuous and interval walking exercise in patients with knee osteoarthritis (OA). Methods: Twenty seven patients with unilateral symptomatic knee OA completed two separate walking exercise sessions on a treadmill at 1.3 m/s on two different days: 1) a continuous 45 min walking exercise session, and 2) three 15 min bouts of walking exercise separated by 1 h rest periods for a total of 45 min of exercise in an interval format. Estimated knee contact forces using the OpenSim software and knee pain were evaluated at baseline (1st minute of walking) and after every 15 min between the continuous and interval walking conditions. Results: A significant increase from baseline was observed in peak knee contact force during the weight-acceptance phase of gait after 30 and 45 min of walking, irrespective of the walking exercise condition. Additionally, whereas continuous walking resulted in an increase in knee pain, interval walking did not lead to increased knee pain. Conclusion: Walking exercise durations of 30 min or greater may lead to undesirable knee joint loading in patients with knee OA, while performing the same volume of exercise in multiple bouts as opposed to one continuous bout may be beneficial for limiting knee pain.