The Effects of Long-Term Walking Exercise on Structural Progression, Symptoms, and Extensor Muscle Strength in Patients with Mild or at High Risk of Knee Osteoarthritis: Data from the Osteoarthritis Initiative

Abstract

Objective To assess the relationship between walking exercise and medial joint space narrowing (JSN) progression, symptoms, and knee extensor muscle strength (EMS) in early knee osteoarthritis (OA) patients. Methods This nested cohort study within the Osteoarthritis Initiative included participants aged 50 and above with knee OA (Kellgren-Lawrence grades 0-2). Walking exercisers were identified using a modified Historical Physical Activity Survey Instrument. Differences in medial JSN, Knee Injury and Osteoarthritis Outcome Score (KOOS), and knee EMS were evaluated through the three-way ANOVA. Results Among 896 participants, 83.4% reported walking exercise. Female walkers showed significant improvements in symptoms (KOOS-Pain: P < 0.001; KOOS-Symptom: P < 0.001; KOOS-Quality of Life (QOL): P < 0.001; KOOS-Function, Sports, and Recreational Activities (FSR): P = 0.007). Similar results were observed in male walkers (KOOS-Pain: P < 0.001; KOOS-Symptom: P < 0.001; KOOS- QOL: P = 0.001; KOOS- FSR: P = 0.009). Walkers showed significantly increased knee EMS at 24 months (Female: P < 0.001; Male: P = 0.003). Female non-walkers had significantly decreased knee EMS at 24 months (P < 0.001). Walkers showed significant improvement in medial JSN (OR = 1.1, 95% CI: 1.0 to 1.2) and KL grade (OR = 1.0, 95% CI: 1.0 to 1.1) compared to non-walkers. Conclusion Walking exercise prevents structural progression and improves symptoms. Meanwhile, the increased knee EMS in all walkers further supports the validity of recommending walking exercises for early-stage knee OA patients.