Running and Knee Arthritis

Do runners get more knee arthritis?

A 2023 systematic review and meta-analysis pooled nine observational case-control studies with 12,273 people, 1,272 of them runners, against a comparison group that ran under 8 km (5 miles) a week. Knee arthritis was no more common in the runners, and no more common at any of the weekly volumes studied, up to more than 48 km (30 miles) a week. Five of the nine studies were rated at high or very high risk of bias, and the authors say it is unclear whether weekly volume is associated with more knee arthritis¹.

The review compares groups, so it does not show that running protects the knee either. And who keeps running may depend on how the knee feels: the authors of the cohort in the next section say so of their own data.

If you already have knee arthritis

The Osteoarthritis Initiative is a US cohort. A 2018 nested study of 1,203 people aged 50 or older with arthritis in at least one knee (11.5% runners) compared runners with non-runners over 48 months. After adjusting for age, sex, body mass index, X-ray grade, the other knee and injury, running was not associated with a worsening X-ray grade or with new frequent knee pain, and was associated with frequent knee pain resolving. Runners were identified from a questionnaire at the 96-month visit, later than the 48-month follow-up. The authors write that running, which is likely shaped by how the knee feels and may mean shorter, lower-intensity sessions, need not be discouraged in people with knee arthritis².

What a run does to the knee on a scan

A 2023 systematic review of 24 studies and 446 knees found that knee cartilage thickness and volume were slightly lower right after running. T2 relaxation time, an MRI measure of cartilage composition, in the joint between the thigh bone and the shin bone was back at baseline within 91 minutes, and existing cartilage defects were unchanged within 48 hours. The authors rate the certainty as very low, call the changes small and apparently transient, and say this suggests a single bout of running is not detrimental to knee cartilage³.

After a full marathon, a 2026 study of 100 recreational runners (200 knees) measured the outward shift of the inner-side meniscus on ultrasound (meniscus extrusion). It rose right after the race, stayed higher through day 3 and was back at baseline from day 4. The authors say whether the change has clinical consequences, or warrants a specific recovery interval, requires further study⁴.

A scan is not a verdict

If an MRI report mentions cartilage wear or a meniscus tear, know how common those findings are. A 2019 systematic review of 63 studies (5,397 knees of 4,751 adults) of knees with no symptoms and no injury found cartilage defects in 24% and meniscal tears in 10%. In adults aged 40 and over the figures were 43% and 19%, against 11% and 4% under 40. The authors say these imaging findings should be interpreted in the context of the clinical picture⁵. Judge a knee by how it works and feels, not by a report alone.

What does raise the risk

The next two reviews are not about runners. A 2025 systematic review and meta-analysis of 131 studies on risk factors for new knee arthritis found that a previous knee injury raised the chance of new arthritis on X-ray, with moderate to high certainty. Overweight or obesity and a previous knee injury together accounted for 14% of new arthritis on X-ray⁶.

After a torn ACL the risk is much higher. A 2022 umbrella review of 13 reviews found knee arthritis about seven times as likely after an ACL injury and 7.7 times as likely after ACL reconstruction, with an estimated 36% prevalence near 10 years after reconstruction⁷.

What to do with it

Keep running, and change the week when a knee hurts:

• Change the week, not who you are. When a knee hurts, cut distance, frequency or speed for a while instead of stopping altogether, and make the easy days easy. In a 2020 international survey of 2,007 health care professionals, most recommended that runners with knee arthritis modify their training instead of quitting. That is what they reported recommending, not a tested treatment⁸. Replace what you cut with aerobic work that adds no lower-body impact, at an easy conversational effort, which is zone 2 in a five-zone model.
• Write down where it hurts and when. Pain around the kneecap, on the outer side and deep in the joint are different problems (see the runner's knee guide and the IT band syndrome guide), and a clear note helps whoever examines you.
• Treat a knee injury as a real event. A previous knee injury raised the chance of new knee arthritis in the review above⁶, so getting a significant injury properly assessed is a sensible precaution.
• See a sports-medicine professional if the pain has not eased after a couple of weeks of reduced load, or if it limits daily life.