A lot of things can affect a man's ability to think straight while running the trails.  Heat, hydration, and nutrition are all important factors when running ultra distances.  Oh yeah, having your brains eaten by the Sampson Bog zombies might also interfere with peak performance.  

But none of that seemed to slow Greg down.  In fact, Greg proved what most non ultra people have thought for a long time... Ultra marathoners have no brains.

Mmm... brains.