When talking about endurance running, my mind immediately jumps to Courtney Dauwalter. In Oct of 2017 she run the Moab 240 mile race by 10+ hours. She's had other "super hero" stories such as pushing through temporary blindless to finish another race. I don't know of any particular feature that allows her to achieve these feats of endurance but the "brain/body" connection seems to be huge part of it since her training volume/intensity doesn't seem to be that much different than her peers.