Hey guys. I'm just reading the Primal Blueprint and I've just read that, according to Mark, long distance running is bad for you!

My question is, what would be considered "long distance running"? I run for 20 minutes every other morning and I enjoy both the feeling I get from it and trying to beat my time - is that long enough to release excessive amounts of cortisol?

I'm not sure whether to go with Mark on this or listen to others in the field who claim that our ancestors would engage in "persistence" hunting where we would regularly run for long distances, pointing to our sweating capabilities, better ability to run long distances and lesser sprinting abilities.

Any responses would be greatly appreciated