Got a mate whos about 5% body fat.. He is in fantastic shape and his fitness is amazing.. Recently done a charity event which the other guy doing it with him lost 5kg in one day was walking a trail which consists of 770 steps to the top and the same path back down so in that 50 times they walked up/down 77,000 steps.. Took them about 34 hours none stop.

Sorry about the pics only ones i could find-