“Running causes knee and hip arthritis”

## The Evidence A 2017 systematic review and meta-analysis by Alentorn-Geli and colleagues (*Journal of Orthopaedic & Sports Physical Therapy*) analysed 125,810 people across multiple studies and found that recreational runners had a 3.5% prevalence of hip/knee arthritis versus 10.2% in sedentary individuals and 13.3% in competitive high-mileage runners. Running at moderate volumes stimulates cartilage nutrient exchange via cyclical loading, and strengthens the muscles that protect joints. The "wear and tear" model of arthritis is largely obsolete — inflammation and metabolic factors drive most OA, not mechanical loading alone. ## Caveats People who already have significant joint damage should consult an orthopaedic specialist before running. Sudden large increases in mileage (overuse injury) are a separate concern from long-term arthritis risk.