Perhaps it seems counter intuitive that runners do not have a higher incidence of knee osteoarthritis or so the preponderance of epidemiologic data contents.After all the peak load of the articular cartilages in running is much higher than in walking or so the kinesiologists tell us and would not the cumulative higher peak load after many miles of running wear out and maybe chew up the articular cartilages.
Or maybe the explanation does not lie in the peak load.
Ross H Miller from the Department of Kinesiology at the University of Maryland offers an alternative view (1) and an alternative analysis of the relevant forces conspiring to "wear out" the knees.
He suggested that peak load is not the relevant variable but rather it is the "average load per distance traveled" which is said to be surprisingly low and purportedly similar to walking.
Ross also discussed the notion of cartilage conditioning .Knee cartilage glycosaminoglycan content( which affects lubrication and shock absorption ) has shown in one study to be greater in recreational runners and even greater in high volume runners.
"... a man hears what he wants to hear and disregards the rest" Paul Simon.The Boxer
1) Miller, RH "Joint loading in runners does not initiate knee osteoarthritis" Exerc Sports Sci Rev 45(2), 87-95,4 2017