This is the latest research that shows that regular running helps PREVENT, not cause arthritis; that stretching may feel good but doesn’t help prevent injuries; and that toe-running is no better than heel-running for injury prevention:

https://www.theguardian.com/lifeandstyle/2016/jul/18/knees-stretching-heel-striking-three-running-myths-debunked

These findings correlate with my own experience as a runner, as well as my clinical experience–the running injuries I generally see are easily-treatable soft tissue injuries of the patellar tendon and IT band, etc., not arthritis, which I see more commonly in non-runners. Although knee arthritis also generally respond well to acupuncture, even better is prevention through regular exercise and through treating injuries in their early and mild stages, before arthriitis sets in.