"We're innovating ourselves out of being dirty, being tired, being afraid," Patterson says. "You don't want to be any of those things on a regular basis and there's a reason there's been progress since the caveman days, but for one weekend day for three or four hours you can go out on a course with your friends and confront your fears, get some scratches on your knees, get dirty, get a big smile on your face and leap through fire -- it makes you remember why you're a human being, an animal and alive." That resonates with a whole lot of Tough Mudder's core participants. Nearly 80% of Tough Mudder runners are male, are an average age of 29 and -- if they're not police, firefighters, military, veterans or extreme athletes looking for something more social -- are guys with office jobs. They're part of a modern economy of labor mobility that forces people to move all around the world. Instead of cities where everybody goes to the same happy hour every week, Patterson says many of the events find working runners that face an insular, tech-aided loneliness. Social media solves it to an extent, but exacerbates it by letting people live off their computer without actually seeing their friends. That's great if you're amassing huge networks of Facebook friends, Twitter followers or Google+ ( GOOG) circles, but takes away the social element that frees the "badass underneath." If all of that sounds a bit familiar, so should "His name is Robert Paulson." "We tend to liken it to the movie Fight Club with Brad Pitt where you have all these office workers going in to fight each other because of this human urge to get extreme," Patterson says. "We're not quite there and it's not the same as punching each other in the face, but it's an identity that you're adopting." Not that these races are a solely male experience by any means. Warrior Dash's Robinson says his company's events skew about 50-50 male-to-female and pull in not only officers from local police forces in Ohio and Oklahoma, but desk athletes from companies including Keen Footwear, PriceModern Furniture and Peterbilt Motors ( PCAR). "One of my favorite groups that I've seen was two women who came in their wedding dresses and were both divorced," Robinson says. "They ran the entire course in those now muddy and probably destroyed wedding dresses." Age isn't much of a factor, either. The Spartan Race obstacle and mud event was founded by two adventure runners in 2010, but culls the participants for its 18 races from multiple demographics. Serious enough to have four tiers of competition to separate the mud-splashing fun runners from the boulder-lifting competitors but silly enough to give participants spray-on fake abs afterward, Spartan Race is just as likely to draw runners from their college dorms as it is to pry them from their cubicles.