Does running wear out your knees?

I get this question a lot, and often as a statement from runners who assume their osteoarthritis is a result of their past running.

I was recently sent this article by a doctor friend who wanted my thoughts on it because the “study” claims that running does not cause osteoarthritis (the wearing down of the cartilage) in the knee.

Here is my response:

I think running on a treadmill set to an incline (of 5% or higher), or on grass, dirt trails, and other natural surfaces does not wear cartilage down for most people. 
Pavement, on the other hand, which has only been around for about 100 years, is another story. 
I also think the modern shoe is a problem. Flat leather soles, sandals, bare feet, etc. don’t interfere with the basic gait mechanics humans enjoyed until about 100 years ago when rubber soles and lifted heels were invented. 
And obesity was extremely rare over 100 years ago because we didn’t have processed food, refined vegetable oils, and other crap causing the body to break down, fatten up, and become inflamed. 
Humans weren’t nearly as sedentary before cars, TVs, computers, and cushy recliners came on the scene, also all within the last 100 years. 
These are some of the factors they should be studying to really figure out why we have this epidemic of osteoarthritis and hip and knee replacements are so common. 
If we had a time machine and could take a trip back 200 years, we would be astounded at how few degenerative conditions could be found (and even less, going back in time before sugar existed). 
Thanks to trauma care, emergency surgery, antibiotics, and a few other drugs, our modern medical system keeps us alive much longer, but with a lower quality of life than our ancestors.

That’s a summary of some of my thoughts on the subject. And the solution is embedded in those thoughts, but to summarize, if you like running, do it on an incline treadmill, or outside on natural surfaces, with “barefoot” style shoes. And don’t start until you are at a healthy weight. And start slow, and build up gradually. And replace your inflammatory foods with anti-inflammatory foods. And drink more Hudor.

And as Forrest Gump said, “That’s all I have to say about that.”