Earlier quoted context omitted.
I could never understand why so many people run as a sport, when nearly all runners eventually develop joint problems, many requiring knee replacements (which you supposedly can't run on).
This oft-repeated claim is factually inaccurate. Runners and former runners, as a population, have better knees than non-runners.[0] [0]: https://www.ncbi.nlm.nih.gov/pubmed/27333572
The study itself says:
> This was an observational study where people chose whether or not they wanted to run; therefore there is always the possibility that people stopped running because they had knee pain.
That's a pretty big flaw in their study.