Flyman: Have you got any experience? reputation applications easy payday in advance alphabetical agent The varied obstacles of these competitions, from fire jumps to climbs over cargo nets, pose their own challenges to participants, and obstacles that call for sheer physical strength aren't the only risk on the course. Temperature obstacles, like the "Arctic Enema" in Tough Mudder races – an obstacle that requires competitors to dunk themselves in a dumpster filled with water that's kept just above freezing – offer their own set of hurdles to overcome. "If you put your body into ice, it's not going to function the way you would think it would in just normal water," certified running coach Jennifer Kimbel says. In water that cold, she explains, muscles constrict and aren't as effective as they are at normal temperatures.