Contrary to what you may have thought. This New York Times piece will shake up your ideas a little.
“But despite entrenched mythology to the contrary, runners don’t seem prone to degenerating knees. An important 2008 study, this one from Stanford University, followed middle-aged, longtime distance runners (not necessarily marathoners) for nearly 20 years, beginning in 1984, when most were in their 50s or 60s.”
