Is running bad for your knees?
No, running is not bad for healthy knees. Multiple long-term studies show recreational runners have lower rates of knee arthritis than sedentary people. However, rapid mileage increases, poor form, weak glutes, and worn-out shoes can cause knee pain in runners.
The 'running ruins your knees' myth is one of the most persistent pieces of bad advice in sports medicine. Multiple long-term studies, including a 2017 meta-analysis of over 125,000 people, found that recreational runners have a knee osteoarthritis rate of 3.5% compared to 10.2% for sedentary people. Elite runners do show slightly higher rates, but that's from decades of 150+ km weekly volume. For regular runners doing 30-60 km per week, running actually protects knees by strengthening the muscles around them, maintaining cartilage through cyclic loading, and keeping body weight in check. Knee pain in runners usually comes from four causes: ramping up mileage too fast (more than 10% per week), weak glutes causing knee valgus (inward collapse), worn-out shoes past 800 km, and tight hips limiting stride mechanics. None of these are inherent to running — they're all fixable. If you're overweight, have existing knee injury, or haven't run before, ease in with walking and strength training first. But 'I can't run because of my knees' is almost always wrong for a healthy adult.