This is dangerous. My friend blew out his knee pushing too hard with trailrunning, and now he can never run again.

If you fall due to tripping over a rock or something then of course you can damage your knee. The point is that running a lot won't necessarily wear your knees out.

"Blowing out a knee" is a completely different issue to osteoarthritis of the knee.

Telling people not to run due to a misconception about perceived harm is much more harmful than the risk of a serious knee injury from running.

Curious what you can find about IT bands? I used to run triathlons. Stopped when I had a long recovery from a cracked foot. 10 years later I have chronic IT band tightening that pulls my knee out of alignment and causes constant pain.

When I was doing triathlon, I was in the Clydesdale division because I had a physique more like a football player than a runner. I've often wondered if my leg/knee problems of today are casually related to my choice to seriously do an exercise against body type.

You should do a very thorough course of pilates and core strengthening, and possibly some squats/leg presses. The IT bands and other problems that untrack are all about balanced strength groups in your butt/groins/core.

I had patellar chondromalacia for about a year after one of my Ironmans and I couldn't get it to go away. I started doing a mat pilates and it went away within a could weeks.

Then I had back problems kinda like sciatica, and that was solved with the leg presses, but I feel the leg presses helped make the knees even healthier.

The other issue with running as a triathlete, especially a clydesdale, is that you may be excessively heel planting. It can be hard to transition to midfoot planting for a big dude, but it is much much easier on your knees.

You'd have to do some sprinting on your toes, very unorthodox for triathlons, but even then it is very hard to change the fundamental style of running.