I wrote the following story for both the Charlotte Observer and The News & Observer; it ran in both papers May 31, 2011. It runs here in an expanded form with links.
They go by names such as the Gladiator, Warrior, Rugged Maniac, Spartan and Tough Mudder. They feature obstacles ranging from mud pits covered by barbed wire to a gauntlet of dangling, live electric wires. To pitch themselves they use adjectives like “grueling” and “insane,” boast that the Navy SEALS and British special forces had a hand in their design, and feature promotional videos of paramedics carting bloodied contestants off the field of battle.