Running is great TOO much running can cripple you.
The dose it is always the dose. You bumped up to 50 and now have a chronic injury you think that PF is just gonna go away? WTFU put down that running crack pipe. Moderation 90 percent of the time with occasional periods of hammering for a short time is my advice.
-Maintain your fast twitch fibers without metabolic stress
-Cross train easy to supplement aerobic fitness
-Do the ozone stuff which is anything over 70percent of mhr sparingly
The running world plays down the long term health risks of too much running shame shame shame. Be smart most of the runners my age who have ran a lot of miles have chronic injuries. I am 64 and can still pick em up and put em down. But I have made many mistakes like ignoring pf until I was unable to run/walk without pain.
One more thing....
I can match my age graded scores doing way less hard stuff are the tables soft or was all that macho hard stuff I did in my early 40s worth nothing? Those last few seconds per mile will shorten your running career or too many races or too much volume. Enjoy running race now and then do a little hard stuff but try not to become obsessed like so many runners do.