MYTH BUSTED · RUNNING MYTHS · 8 MIN READ
The Wear-And-Tear Myth That Refuses To Die — And What Nearly 115,000 Runners Actually Show
My mum has told me, more times than I can count, that I’m going to ‘ruin my knees’ by the time I’m forty. She’s not alone — ask almost anyone why they don’t run and ‘bad for your joints’ shows up somewhere in the first three reasons, usually right after ‘no time’ and ‘I hate it’.
I used to nod along. Then I actually went looking for the studies behind the claim, and what I found was close to the exact opposite of what everyone — including a couple of GPs I’ve spoken to — seems to believe.
Let me be direct about this, because I think you deserve the actual evidence more than you deserve reassurance: the largest studies we have on this show recreational runners have lower rates of knee arthritis than people who don’t run at all. Not the same rate. Lower.
This isn’t a fringe finding from one small study. It’s the consistent pattern across five decades of research, from 20-year prospective cohorts to systematic reviews covering well over 100,000 people. So let’s go through what’s actually been measured — properly, with the numbers, not the folk wisdom.
Recreational runners have a 3.5% rate of hip or knee arthritis. People who don’t run at all: 10.2%.
— Systematic review & meta-analysis, Journal of Orthopaedic & Sports Physical Therapy, 2017 (17 studies, 114,829 participants)
For most of the 20th century, osteoarthritis was explained almost entirely as a ‘wear and tear’ condition — the idea that a joint is a bit like a brake pad or a tyre, and the more you use it, the faster it wears down. It’s an intuitive model. It is also, as it turns out, not really how cartilage works.
Some of the earliest studies that appeared to support the myth followed elite or ex-elite athletes — people running well over 60–90 miles a week for decades, often through injury, without any of the structured recovery culture modern coaching insists on. Those findings got generalised to ‘running’ as a whole, when they only ever described a small, extreme slice of it.
There’s also a naming problem. ‘Runner’s knee’ is the common term for patellofemoral pain syndrome — an overuse condition involving kneecap tracking and the muscles that support it. It has nothing to do with osteoarthritis. But the shared name has spent decades quietly implying the two are related.
Combine an intuitive-but-wrong mechanical model with a handful of extreme-outlier study populations and a confusing shared name, and you get a myth robust enough to survive half a century of contrary evidence.
Start with the Stanford cohort that’s cited more than almost any other on this topic. Researchers tracked 45 long-distance runners and 53 non-running controls, all around 58 years old in 1984, with serial knee X-rays over the next 18 years. By 2002, the runners did not have more osteoarthritis than the non-runners (20% vs 32%) or more severe osteoarthritis (2.2% vs 9.4%) — if anything the numbers ran the other way, though not by a statistically significant margin. The honest conclusion: two decades of long-distance running produced no evidence of accelerated joint damage.
A separate cross-sectional study drawing on the NIH’s Osteoarthritis Initiative looked at 2,637 adults with an average age of 64, around 30% of whom had run at some point in their life. Runners were not at higher odds of knee pain, X-ray osteoarthritis, or symptomatic osteoarthritis than people who had never run — current runners actually scored somewhat lower on every single measure.
Then there’s the big one: a 2017 systematic review and meta-analysis pooling 17 studies and 114,829 people. The headline numbers are worth sitting with. Recreational runners: 3.5% rate of hip or knee arthritis. Sedentary non-runners: 10.2%. Competitive or elite runners: 13.3%. The group with the lowest arthritis rate in the entire dataset wasn’t the people who didn’t run. It was the ordinary recreational runners.
An updated systematic review published in 2023, adding roughly 8,000 more patients to the evidence base, confirmed the pattern: running is not associated with worsening symptoms or radiographic signs of osteoarthritis in the short term, and appears to be protective against general knee pain. Runners in the studies that tracked long-term outcomes were also less likely to progress to a total knee replacement than non-runners.
Unlike a mechanical part, cartilage is living tissue that responds to load roughly the way bone and muscle do: moderate, repeated loading stimulates it, and prolonged inactivity weakens it. Cartilage is largely water held in a mesh of proteoglycans — compressive load pushes fluid out, and the tissue draws fresh, nutrient-rich fluid back in as it recovers, a bit like a sponge being worked. That cycle is central to keeping the tissue healthy, not a mechanism for wearing it away.
MRI studies of marathon runners show exactly this: measurable, temporary shifts in cartilage water content and thickness immediately after a marathon, which resolve within hours to a couple of days. That’s consistent with a normal physiological loading response — not damage.
Longer-term structural comparisons tell a similar story. Cross-sectional studies of long-term runners versus sedentary controls have found runners with thicker cartilage in some load-bearing regions of the knee and no evidence of accelerated degeneration, supporting the idea that the tissue adapts positively to running load rather than eroding under it.
Perhaps the most striking data point on this comes from researchers who used mobile MRI to track runners’ knee cartilage across a 4,486km transcontinental multistage ultra-marathon — run continuously across several weeks. Cartilage showed loading-related changes early in the race, but no further deterioration through the second half, and none of the athletes who dropped out did so because of knee problems. Even at that extreme, cartilage adapted rather than failed.
Cartilage isn’t consumed by movement. It’s maintained by it.
Good evidence includes its own exceptions, and this one has a genuine, honest caveat. In that same 2017 meta-analysis, competitive and elite runners — typically training at 60+ miles a week for years — showed a higher arthritis rate (13.3%) than recreational runners (3.5%). Still not dramatically above the sedentary group, but clearly higher than moderate recreational training. Volume matters, and there does appear to be a dose-response pattern at the very top end.
The other established risk factors have nothing to do with the simple act of running at a sensible volume: a previous knee injury that wasn’t properly rehabbed, a higher body mass index that increases mechanical load per stride, sharp increases in training volume without time to adapt, and continuing to run through joint-specific pain rather than addressing it.
The actual risk factor isn’t ‘running.’ It’s running through injury, running enormous volumes without recovery, or carrying unaddressed joint damage into training. For the overwhelming majority of people reading this — doing three sessions a week at a conversational pace — none of that applies.
It’s the common name for patellofemoral pain syndrome — an overuse condition related to kneecap tracking and the strength of the muscles around it. It’s usually resolved with targeted strength work and sensible load management. It is a completely different condition from osteoarthritis, despite what the shared vocabulary implies.
Prolonged inactivity reduces circulation of the synovial fluid that feeds and lubricates cartilage. It’s not a coincidence that population-level data consistently show sedentary people with higher rates of knee osteoarthritis than recreational runners, not lower.
How much force moves through your knee joint on each stride depends heavily on quad and glute strength — arguably more than the number of kilometres you’ve logged. Weak muscles around the knee are a far more consistent predictor of running-related knee pain than total distance.
It responds to load the way bone responds to resistance training — strengthening under the right amount of stress, weakening under none at all. The tyre analogy that built this myth was never the right one to begin with.
Your knees are not a countdown timer running out with every mile logged. The dominant, repeated finding across studies covering hundreds of thousands of people combined is that recreational runners have equal or better knee outcomes than people who don’t run — and meaningfully better outcomes than people who sit still.
The genuine caveats are narrow: don’t run through sharp, localised, or worsening joint pain. Don’t ramp your mileage up dramatically overnight. And if you’ve had a significant prior knee injury, get it properly assessed and rehabbed before increasing load. Outside of that, three sessions a week at a sensible pace is, if anything, doing your knees a favour.
Your knees were built to move. The myth had it backwards.
RUN.
• Chakravarty EF, Hubert HB, Lingala VB, Zatarain E, Fries JF (2008). Long distance running and knee osteoarthritis: A prospective study. American Journal of Preventive Medicine, 35(2).
• Lo GH, Driban JB, Kriska AM, et al. (2017). Is there an association between a history of running and symptomatic knee osteoarthritis? A cross-sectional study from the Osteoarthritis Initiative. Arthritis Care & Research, 69(2).
• Alentorn-Geli E, Samuelsson K, Musahl V, Green CL, Bhandari M, Karlsson J (2017). The association of recreational and competitive running with hip and knee osteoarthritis: A systematic review and meta-analysis. Journal of Orthopaedic & Sports Physical Therapy, 47(6).
• Updated systematic review at short-term follow-up (2023). Effects of running on the development of knee osteoarthritis. PMC / peer-reviewed sports medicine literature.
• Timmins KA, Leech RD, Batt ME, Edwards KL (2017). Running and knee osteoarthritis: A systematic review and meta-analysis. American Journal of Sports Medicine.
• Mobile MRI field study of knee cartilage during a 4,486km transcontinental multistage ultra-marathon using T2* mapping (2020). Scientific Reports.
• Lo GH, Musa SM, Driban JB, et al. (2018). Running does not increase symptoms or structural progression in people with knee osteoarthritis. Clinical Rheumatology, 37(9).
Does running actually damage your knee cartilage?
No — the largest available studies show recreational runners have equal or lower rates of knee osteoarthritis than non-runners. Cartilage responds to moderate mechanical loading by adapting, similar to how bone responds to exercise.
Is ‘runner’s knee’ a sign of arthritis?
No. ‘Runner’s knee’ usually refers to patellofemoral pain syndrome, an overuse condition related to kneecap tracking and surrounding muscle strength — a different and generally treatable condition from osteoarthritis.
Are marathon runners at higher risk of knee arthritis than casual runners?
The clearest increase in risk shows up at competitive or elite training volumes, not typical recreational mileage. A 2017 meta-analysis found elite/competitive runners had a 13.3% arthritis rate compared with 3.5% for recreational runners.
Is it worse for your knees to run or to be sedentary?
The research consistently points the other way. Sedentary individuals show higher rates of knee osteoarthritis (around 10.2% in the largest pooled analysis) than recreational runners (3.5%).
Should I stop running if my knees hurt?
Sharp, localised, or worsening joint pain deserves proper assessment — don’t run through it. General muscle fatigue or breathlessness is a different signal and a normal part of training. If in doubt, get it checked before continuing to increase load.