I started doing most of my mileage on dirt paths/trails to avoid the unforgiving hard surfaces. i.e. in a recent 100 mile week, I did 15-20 miles total on roads
So far I've observed some great benefits. I am able to bounce back much quicker on long runs and I no longer have the aches/pains I dealt with when I mostly ran on the roads.
I did my highest mileage totals ever 80,90,100,110,80 for this recent buildup and I feel 100% healthy with no aches/pains whatsoever.
It seems like the Kenyans take this philosophy by doing the majority of their training on dirt roads.. I think they're onto something here.