How The Speed Project's Nils Arend Created the Hardest Relay Race on Earth

Running isn't an "extreme" sport, at least not in its typical form. Line it up next to mountain climbing and bungee jumping, and a jog around the neighborhood -- or even a trail run -- is comparably tame, however, like with any physical activity, there are the rare few that will take it to extremes. For a small but growing sect of the running community, a marathon simply isn't enough to scratch their itch for the sport.Nils Arend has created his own tribe of go-hard, die-hard runners with The Sp...