These guys are really amazing. The extreme endurance races are some of the most difficult athletic events imaginable. But for the most part there are no fans, no sponsors and no major media attention. Races like this are a rare example of pure sporting events, where it's just you against the howling wilderness. Just commuting across town at ten below is enough to sap every bit of my energy. Drop the temp another twenty degrees and add fierce wind and remove anything resembling a proper trail, then increase the distance a hundred fold, and you've got some idea of these races.