After three hours of climbing walls, crawling through tunnels, scrabbling under barbed wire, swimming in ice water, hoisting cement blocks and other cruelties, you come to a 50-foot trough of icy mud. Dozens of yellow wires hang from its wood-plank roof like jellyfish tentacles. The wires sting like jellyfish too, because they’re electrified. This is ­Electroshock Therapy, the last of 32 obstacles on the 10-mile course. You’re wet, freezing, wheezing, bruised, cramping, spent. There’s only one thing to do.

Actually two. You could crawl under the wires, gargling muddy water and wasting time. But that’s not you, is it? No, you charge through the live wires at a run, yelling “Piss! Shit! Bite me!” and assorted ape grunts as the wires kick sparks off your face and aching limbs. Finally, six seconds later, it’s over. Yes! Now it’s a half-mile jog to the finish line. You’re rounding the last turn into the stadium, where loudspeakers pound Guns N’ Roses as you wave your mud-caked paws at the crowd. Fans cheer; your buddies hug you. You just survived the World’s Toughest Mudder, the ultimate test of the world’s most rugged new sport. Now you can strip off this wet suit, rinse off, grab a blanket and a parka and a beer. And sit down.

Unless you want to win. In that case you’ll need to start over. To win you’ll need to run the 10-mile obstacle course again. Eight more times.

“Tough Mudder is the worst day you’ll ever have. And the best,” one mudder says.

A cross between endurance race and boot camp, the world’s fastest-growing sport inspires extreme descriptions. It’s been called a masochist’s marathon and more:

“Probably the toughest event on the planet.”

“A real-life fight club.”

“Ironman meets Burning Man.”

“Trial by fire, ice, dirt, monkey bars, electric shocks—and more fire.”

There are plenty of other extreme sports—the traditional 26.2-mile marathon, plus ultramarathons of 50 kilometers and up, triathlons (swim, bike and ride), Ironman triathlons (swim 2.4 miles, bike 112 miles, then run a marathon, you nut), and newer events such as Spartan Race, Muddy Buddy, Dirty Dash and Rugged Maniac, most featuring obstacles, some involving tree chopping, vegetable slicing, beer drinking, fighting American Gladiators–style bodybuilders armed with Nerf lances, even memorizing the names of U.S. presidents. The boot-campy ones have been growing quickly, challenging older events the way MMA beat down boxing a decade ago. And Tough Mudder, with almost a million adherents, leads the field. Which fits its cocky corporate goal: “We aim to replace Ironman as the preeminent brand in endurance sports.” Not bad for a concept dreamed up four years ago at Harvard, like Facebook, by a pasty entreprenerd, like Facebook, with a big boost from Facebook.

In 2009 Will Dean, a tall, sleepy-eyed veteran of the British government’s countert­errorism unit, sat in a chair-desk at Harvard Business School, defending his entry in the school’s famous Business Plan Contest. His pitch: an endurance sport based on British Special Forces training, one that could top what he termed the “grim monotony” of marathons and triathlons with the bracing variety of military ­conditioning—plus music, killer blogs, pictures and podcasts, friendship, even fun.

A marketing professor flipped through Dean’s proposal. “Rope ladders. Crawling through mud,” he said. “Who would do this?”

“I think I can get 500 participants to pay about a hundred dollars each.”

“And if they survive your obstacle course, what will they win?”

“A headband.”

Dean lost the Harvard contest to a team whose idea became CloudFlare, now a web-security firm backed by investors to the tune of $20 million. But he kept plugging. He moved to Brooklyn and brought in an old boarding-school chum, London attorney Guy Livingstone, as chief operating officer. They pulled together $20,000 in seed money, $480,000 short of Facebook’s start-up stake five years before. In their first and most crucial investment, Dean and ­Livingstone spent $8,000 on Facebook ads. “They were still cheap in 2010,” Dean says. Soon Tough Mudder had 11,000 Facebook likes. The founders spent the rest of their stake renting a ski resort in Pennsylvania, hiring construction crews to build obstacles, checking the obstacles for splinters and stray nails, and rounding up a medical team, cleanup crew and volunteer firefighters to keep a lid on the wall of flames at the last challenge. “Then we started worrying.”

They opened registration. As the online tally shot into the upper hundreds, Dean thought there might be a bug in his website. No, there were just more weekend warriors and cross-training jocks than anyone knew, a Generation P90X hungry for a killer workout. Instead of 500 entrants, the number Dean had pulled out of his hat at Harvard, the first Tough Mudder boasted a field of 4,500. Entrants paid from $70 for early-bird entry to $100 for “Lazy Ass Late Entry,” adding up to a gross of more than $250,000. Dean and Livingstone had just made 10 times their investment in a week.

All he had to do now was stage the thing—a new sport anxiously awaited by 4,500 highly motivated customers who didn’t realize that Tough Mudder LLC consisted of Dean, Livingstone and a few interns. “We were incredibly naive. We thought everything would go according to plan,” Dean recalls. Then the sun came up on Sunday, May 2, 2010, the dawn of the Tough Mudder era. “We found climbing walls that were supposed to be 12 feet tall were only five feet.”

Instead of scaling the walls like marines, entrants hopped them. “And we’d mismeasured the course. It wasn’t the seven miles we promised but more like five and a half. Which seemed like a blessing when we ran out of drinking water.” Somehow everyone made it to sundown. Happy mudders talked up the event. The founders put on two more Tough Mudders that year, grossing $2.2 million. Three years later they’re knee-deep in mud money.

As a business Tough Mudder is almost evilly simple. It’s an experience, not a race. As Dean says, “If you climb a mountain, nobody asks how long you took to do it.” Nobody pays you either. Dean and ­Livingstone bet that Tough Mudder T-shirts, tattoos and the now-iconic orange headband that goes to each finisher would mean more to their public than cash prizes. And with no cash prizes, they kept entry fees low and revenue high. After expenses, including a free beer for everyone who finished—one beer—the rest was profit. They banked enough in 2010 to expand to 14 events in 2011. Total revenue: $22 million. Last year’s schedule jumped to 35 events in 16 states plus Australia, Canada, Scotland and England, for a take topping $70 million. This year’s schedule features more than 50 events in those countries plus Germany.

The wires at Electroshock Therapy might spark and bite, but it’s not the toughest Tough Mudder obstacle. Nor is Arctic Enema, a jumbo tub of ice water that mudders have to swim, ducking under a wall festooned with barbed wire. Tougher still is Everest, a greased quarter pipe 15 feet high, and here’s where Tough Mudder differs from Ironman and every other race. Some mudders may be fast and sure-footed enough to run halfway up, grab the rim and pull themselves over, but others can’t make it. Six and a half miles into the course, their legs are jelly. They’ll take a running start, charge up the ramp and fall just short. Some get their fingers to the top, then cuss and groan as they lose their grip and slide back. Another running start, another try. This can go on for 10 tries over 20 long minutes. Everest is so steep, you’d probably find half the mudders in a writhing mass at the base of the ramp if not for the pledge that sets this game apart. “I put teamwork and camaraderie before my course time,” reads the Tough Mudder pledge. “I help my fellow mudders.”

When the curved wall proves too steep for some entrants, others wait. They yell encouragement: “C’mon, you’re killing it. You got it this time!” They perch at the top of the wall, reaching down to grab a hand or wrist and haul the next mudder to the top. Something similar happens at the 20-foot climbing walls elsewhere on the course: Stronger mudders form human ladders, letting weaker ones climb their backs to the top, where war whoops and bro hugs ensue.

“That’s the spirit!” Mark Givens yells. A tall, mustached Iraq war vet decked out in a poncho and sombrero, Givens is new to the sport—“I ran my first Tough Mudder this year”—and isn’t entered this day. He doesn’t know anyone who is. “Don’t need to know ’em to support ’em,” he says, ringing a cowbell for every mudder going by. “I’ll tell you something. I was in the U.S. Marine Corps for 28 years, and these bastards right here are the toughest I ever saw. I’ve run nine marathons, and you know what? Marathons are boring. With this thing, you got variety. Fun! Those electric wires? It’s like a rattlesnake bite—you do the funky chicken, check to see you’re still alive and keep going. And maybe you can’t get over Everest, but the other guys pull you up. ­Teamwork—that’s what makes this thing cooler than a marathon.”

Like a lungfish rising from Mesozoic muck, this thing evolved. It might have died with a name like Badass Ninja Jog, a name Dean actually considered. He was sitting in a Boston bar with friends four years ago, feeding his laptop a list of words that might fit his still-­nameless sport. Challenge. Ninja. Badass. Run. Jog. Dash. “Warrior Challenge. How’s that sound? Or Ninja Battle. Check to see if ­ is available.”

“Try this,” Dean said. “Badass Mudder. BAM for short.”

“It’s better than your other lame names, Will.”

Then it hit him. Like a spark. “Tough Mudder. ‘I want to be a Tough Mudder,’?” he said, trying out the sound of it.

That first Tough Mudder on Pennsylvania ski slopes featured awards for best mullet and best costumes: Most Bad-Ass for the best, Most Ass for the skimpiest and Most Likely to Have Been in the Village People for cops, leathermen and Native American chiefs. One early obstacle, Blood Bath, called for entrants to eat a fiery habanero pepper and plunge into a pool of red ice water. The founders dropped Blood Bath when mudders began puking in the water. Puking and worse. Hence an unofficial pledge: Challenges should not be digestive.

Tough Mudder comes complete with a corporate wink. Over photos of “ridiculous team costumes,” ­ announces that “Mudders do not take themselves too seriously.” Even as eight-figure revenue and corporate sponsors make the sport more respectable, you can still see the occasional SpongeBob or Batman costume at Tough Mudder events. You still run past jokey signs on the course:


The death waiver, at least, is real. A three-page, single-spaced release describing Tough Mudder as “a hazardous activity that presents the ultimate physical and mental challenge,” the death waiver is both a legal document and a sales tool. Signed by every entrant, it holds Tough Mudder LLC blameless for injuries due to “smoke and open flames, barbed wire, pipes and electric shocks, inadequate first aid and/or…errors in judgment by personnel working the event.” Mudders agree that it’s their job to inspect every inch of the 10- to 12-mile course and hold themselves liable for “broken bones, torn ligaments, concussions, exposure, heat-related illness, mental stress or exhaustion, infection and concussions.” Maybe concussions make the list twice because you may be concussed. The waiver goes on to absolve Tough Mudder LLC of any responsibility for mudders’ “spinal injuries and paralysis, stroke, heart attack and even death.” A subsection adds possible death sites, “including but not limited to stands, sidewalks, parking areas.…” The list includes “restrooms,” presumably in case some poor mudder makes a toilet bowl his final Arctic Enema.

Still, the grungy spirit of Tough Mudder gets a little less ironic as Under Armour, Dos Equis and other brands sign on as sponsors. Less like a party, more like a business. This year the empire will expand into 70,000-square-foot headquarters in Brooklyn, where Dean, now 32, still lives with his fiancée and rides his bike to work. His company outgrew its old HQ by growing from eight employees to more than 120 in less than two years. They tend to be young, fit and resolutely on-message about the Tough Mudder experience, one that arrives engineered from the mud up for a generation that values experience above all else and craves the social ammunition—­photos, videos, tweets—events like Tough Mudder provide. Climbing a mountain is sweet, but posting a photo from the summit to the envy of your Facebook friends is even sweeter. You can buy a ticket for Coachella. You have to survive Tough Mudder.

“Experience is the new luxury good,” one lean, T-shirted executive says, showing off a Lego model of a climbing wall, a gift from a Tough Mudder fanboy, and a photo of another fan who hung yellow wires on his head and went out on Halloween as Electroshock Therapy.

“We live the brand,” says another.

“We’re not like our parents’ generation,” says a third. Meaning not settling for a suit-and-tie job and saving up for a McMansion. “We’re about what we do, not what we own.”

If it sounds a little canned, it’s not because they don’t mean it. It’s because staying on-message is part of the curriculum at Tough Mudder University, the corporate training program. Employees read Starbucks company history for tips on how to expand while maintaining quality control. They study the way JetBlue formed a “countercorporate” culture and how companies mine data on consumer habits. They discuss how the reality show The Ultimate Fighter helped UFC establish its brand. (Don’t be surprised if Tough Mudder turns up on cable as a reality show pegged to the season-­ending World’s Toughest Mudder.) They discuss how their brand is more like Harley-­Davidson—a social club, a state of mind—than like any lame-ass traditional sport. And they prefer to avoid questions about Mr. Mouse.

Billy Wilson, a.k.a. Mr. Mouse, is a retired British soldier who claims Will Dean stole his idea. In 1986 the colorful, quotable ­Wilson, who once ran the London Marathon in costume—as the back end of a horse—began hosting ­military-style obstacle races on his farm in England’s Midlands. “I did not invent cross-country running nor army assault courses,” he says. “What I did was put them together, then added my own quirky names of terror-testing tortures.”

Dean visited Wilson and studied his Tough Guy races prior to developing his Tough Mudder business plan. He also researched other obstacle runs and insists he couldn’t “steal” such commonplace ideas. A Harvard review found no clear wrongdoing but cited Dean for bending the university’s standards of honesty and integrity. So Mr. Mouse sued Tough Mudder in 2010. Dean’s company settled the lawsuit by paying a reported $725,000, but that didn’t stanch the bad blood between them. Mr. Mouse, who has called Dean “a scoundrel” and a “squelchy plagiarist,” sent ­playboy an e-mail promising he’d expose Dean once and for all in 2013.

Another rival, Spartan Race co-founder Joe DeSena, told Outside, “There’s not a person I despise more than Will Dean. Every day I wake up just out of spite for the guy.”

Meanwhile Dean seems as cool as an Arctic Enema. “We’re building a brand,” he says. End of story. For now, anyway.

On Saturday more than a thousand mudders gather at Raceway Park, a rusty old drag-race and motocross arena in Englishtown, New Jersey, for the World’s Toughest Mudder marathon. The goal: Run as many 10-mile laps as possible in 24 hours. The format makes WTM more demanding than any Ironman triathlon. In fact, the annual Ironman World Championship has gotten easier since it began in 1978. That year’s winner took 11 hours and 46 minutes to swim 2.4 miles, bike 112 miles and run a marathon, while today’s Ironman champions do the same in a little over eight hours. At the 10-hour mark they’re getting massages and reading congratulatory texts.

Tough Mudder is harder, or at least hard longer, which happens to be a motto of one of the best teams in the competition, Nine Inch Males. At WTM, efficiency only makes the ordeal more demanding. Last year’s winner, Junyong Pak, an engineer from Beverly, Massachusetts, completed seven laps. It will take more than that this year, and who knows how many laps the champion will have to run in 2020. Fifteen? Twenty? Twenty laps would be 200 miles and 640 obstacles at a seven-minute-mile clip, which may not be humanly possible.

“We’re testing limits,” Dean says.

Only the top five percent at 34 regional events qualified for this Mudder. Those elite 1,200, la crème de l’enema arctique, stretch and crack their necks behind the start-finish line a little before 10 a.m., wishing each other a happy Mudder’s Day. Then loudspeakers blare “Go, go, go!” and the race is on. Twenty-three hours, 59 minutes and 45 seconds to go.

Defending champ Pak zips ahead at a quick jog. Pak, 34, thinks eight laps might win—80 miles by this time tomorrow. “If it takes more, I’m ready,” he says. “Because I’m really competitive.” A lean-muscled running machine with a 2:33 Boston Marathon to his credit, Pak says he’s not a great athlete. “But if it comes down to who wants it more, the other guy better have a Ph.D. in hurting.” Calling Tough Mudder “voluntary torture,” he says he’s the man to beat.

Two hotshots dog his steps in the early laps. Nikolay Nachev and Bryce Wilk, skinny upstarts with family and friends jogging along the course with them, cheering them on, stick with the champ through three and a half laps. That’s 35 miles—more than a marathon, more than most of the other mudders will complete in the next 24 hours. Pak, Nachev and Wilk are already an hour ahead of the rest of the pack. “Those two guys were sticking with me step for step, like it’s a footrace, which was pretty annoying,” Pak later recalls. “I had two thoughts. One was, It’s gonna be a long night. The other was, They’re gonna lose.” When Nachev ducks into a warming hut, one of five heated tents on the course stocked with drinking water, bananas and energy bars, Pak speeds by, picking up the pace. “I’m thinking, I’m going to drop this guy.” Soon Pak and Wilk, a skinny park ranger from Virginia, are dueling for the lead, going stride for gooey stride through Funky Monkey—where mudders monkey-bar their way over an icy water hazard—while the sun and the ­temperature drop. Leaders don’t rest.

Pak finishes lap five at 9:14 on Saturday night. This is when the cold starts to pull your balls up into your larynx. Early pacesetter Nachev, nursing a sore foot, drops out. Ranger Wilk takes the lead, stretching his margin over Pak to an hour, but Wilk is starting to show signs of strain, his eyes glassy as he maintains a killer pace, stride after stride, 20,000 strides per lap, colder every step.

Pak dashes into his tent on pit row. He peels off his wet suit and trades his cold, wet shoes and socks for dry pairs. “Gotta hustle,” he says. “It’s easy to burn 10 minutes on a pit stop.” It takes almost that long to pull a dry, skintight wet suit up his legs, over his chest and arms—at which point he remembers, “I’ve really gotta pee.”

Full-bladder disclosure: Mudders pee in their wet suits. That quick shot of warmth is a pleasure in the middle of an icy night. Unfortunately for Pak, a team of Tough Mudder videographers is tracking his every move with lights and a boom mike. It won’t do for the defending champ to grit his teeth and soak the crotch of his wet suit to the tune of sibilant relief, so he peels the suit down again, turns away from the camera and fills a Gatorade bottle. Zips back up, hurries back to the drag strip to start his next lap, only to realize he’s misplaced the timing chip that tracks his progress around the course. That’s a 20-minute penalty. Pak cools his sore heels in pit row, waiting out the penalty, kicking himself for his mental error, “I just made two mistakes that cost me 30 minutes,” he says. “Wilk’s an hour ahead of me. That puts doubts in your head. Maybe I just blew it.”

He could quit. No disgrace in that: Out of the 1,200 who started on Saturday morning, only 237 will be running at the end.

Pak shrugs. “Here goes.” Jogging from his tent to the blacktop drag strip that leads to the first obstacle, a mud hill called Cliffhanger, he gives the videographers a wave. Ninety minutes behind the leader, he takes off at a run.

“This is the fun part,” says Amelia Boone.

Boone, 29, leads the women’s division. A round-faced blonde beauty with broad shoulders and eight-pack abs, she was a schoolgirl softball and soccer star before law school and an alpha career at Skadden, Arps—one of the nation’s top law firms—left her dying for a physical challenge. Now she handles corporate bankruptcies during the week and runs endurance races on weekends. Her office in Skadden’s sleek Chicago branch features several dirt-caked Tough Mudder headbands and a skull she won at a ­Spartan Death Race.

Boone is the women’s favorite because Juliana Sproles, a personal trainer from Ojai, California, got frostbite on her foot while winning the female division in the first WTM. A year later Sproles is nowhere to be seen, leaving Boone and 77 other women to measure themselves against Pak and more than a thousand other men. Some say women have a better chance in obstacle races than other sports, due to the role of determination over sheer strength or speed, and maybe the insulating power of body fat. (Male athletes average about nine percent body fat, females 17 percent.) Not that this is easy for anybody. According to one woman who’s both a mudder and a mother, “getting through a Tough Mudder is harder than childbirth.”

Nobody expects Boone to stay close to the men’s-division leaders. “I go as hard as I can before nightfall,” she says, jogging into her third lap. “This is the fun part. From here it gets harder.” Boone, who admits she’s a “gearwhore” on her blog, Race Ipsa Loquitur (hydration tip: “Grape Pedialyte is the bomb”), jogs on as night falls. She keeps going by plotting the course in her head, using the same mud tunnels and ­monkey-bar routes each lap, never slowing down enough to let the cold sap her energy. She stays alert by singing ­Macklemore’s “Thrift Shop” under her breath hour after hour, lap after lap: “I’m just pumped up on some shit from a thrift shop.”

Ten hours into the race she’s still mumbling Macklemore: “That’s a bargain bitch, I’ma take your grandpa’s style——”

The course looks eerie after dark. By midnight most of the field has pitted to eat and sleep or at least rest. Some eat cold soup right out of the can. Some gossip about the tightest sort of Tough Mudder teamwork: loud sex in pit-row tents. Only the toughest keep trudging the course. They wear headlamps that bob like fireflies over the dark, muddy landscape. Follow one to the four-mile mark and you hear labored breathing as a weary mudder approaches. A crunchy tread as he reaches Boa Constrictor, an array of black plastic pipes. A curse as he kneels and chooses a pipe to crawl into. All silent for a minute as he clambers ratlike downhill and then up, emerging with a splash in a pool of freezing mud.

Who wants to spend Saturday night like that? Hundreds of thousands of guys in their 20s and 30s trying to prove they’re not wimps, apparently. One used to wonder if his girlfriend doubted his manliness. “I never punched a guy to protect her. I never built a fire or skinned a rabbit,” he says. After he ran a Tough Mudder, “we both liked me better.” Another weekend warrior told The New York Times that the new sport is “the only chance for a guy like me to feel like King Leonidas.” The paper quoted a sociology professor who called obstacle events “the physical representation of masculinity. By associating themselves with military training, these men are becoming masculine by association.”

Mudder macho turns up everywhere from the bodybuilder in the WTM logo to obstacles emblazoned Ball Shrinker, Dong Dangler and Hold Your Wood. There is no Tough Titty. Still it’s Amelia Boone passing men, not the other way around, as the night wears on. A little before midnight Boone, wearing an orange bib that marks her as the women’s leader, passes a pair of exhausted guys hobbling to the end of their third lap. She’s on her fifth. The founders, monitoring the race, can’t believe Boone’s performance. They never expected a woman to finish in the top 10 percent, much less the top 10.

As Boone laps the cramping, limping men, one of them croaks, “Amelia, marry me.”

Near dawn, it’s 30 degrees out. Scotsman Mark Stirrat reaches Funky Monkey, where contestants negotiate monkey bars over frigid water. Shite, he thinks, a man’s not meant to see his breath when he swims. Stirrat and his ruddy, jolly teammates, the Fuddy Muckers, came all the way from Aberdeen, Scotland for this. Like most mudders they slip off the monkey bars, then splash and wade the rest of the way. Climbing out shivering, Stirrat does jumping jacks to keep his blood going. He then ducks into a heat hut and comes out smiling. “Hot broth and ibuprofen, these are welcome gifts!” He still has six miles to go.

Soon Steve Larson bites the mud. A zookeeper at Sedgwick County Zoo in Wichita, Kansas, buzz-cut Larson is one of the toughest mudders in the field, an ultrajock who thinks marathons are for wusses. “Once P. Diddy and Oprah ran marathons, I thought, Anybody can do that,” he says. So Larson, 33, ran an ultramarathon. He tried the competitive eating tour and won $100 for gulping 14 hot dogs in five minutes, then “had a blast” at a regional Tough Mudder event. Larson has the best description of the electric shocks on the course: “They hurt worse than a penguin bite.” But tonight he cracks a rib on one obstacle and spends 45 minutes trying to climb a 20-foot wall a mile from the finish. At last, weeping with frustration, he quits.

“Not my night,” says the onetime contender.

The hour before dawn is the worst. The course is almost empty, with only the leaders and a few dozen sleepless, dripping diehards plodding through subfreezing cold under a moon the color of ice. Now is when the occasional mudder succumbs to hypothermic shock. His eyes glaze. He mumbles. These hypothermic zombies sometimes curl up in the mud and might die there if other mudders didn’t stumble over them and call for help.

Amelia Boone’s still humming along. She conserves cranial heat by keeping her head above water during ice swims and stays alert by talking to the volunteers manning obstacles and medical tents.

“Doing great, Amelia!”

“Am I?”

“Pak just went through here half an hour ago.”

Pak had outslogged Wilk. Earlier in the night the park ranger, slowed by the cold, ducked into his tent after six laps. He wound up leaving pit row—and the race he led for more than 12 hours—with help from his mother and fiancée. When a course worker gave Pak the news, he pumped his fist. “I’ve got him now,” he thought. “You don’t take a pit stop with an hour lead. At this point you take a pit stop if you’re broken.”

With Wilk down and out, Pak relaxes. He’s sailing through a record eighth lap, one more than his winning total last year, while the sun and rising temps draw mudders from their tents for one more go-round.

Passing the inflatable arch at the start-­finish line, Pak rolls into his ninth lap. Eighty miles and 256 obstacles down, 10 miles and 32 left.

Two hours later, trudging toward Everest, three and a half miles from the finish, he hears a fan call, “You’ve got all the men beat!” This is good news for Pak, who’s suffering. Tendinitis in one knee, frosty feet, cramps—he can barely walk, much less run. It’s good news until the fan adds, “But ­Amelia is five minutes behind you.”


One of 13 women still in the race, lawyer Boone has been chipping away at Pak’s lead since midnight. Singing under her breath, chatting with other mudders, forcing herself to jog while they walk, she’s pulled within four minutes with three miles left. She’s close enough to see Pak at Electric Eel. He saves time by rolling sideways through the mud, under the live wires, then stands, wiping black goo from his eyes. Visibly gathering what strength he has left, he takes off at a trot.

Mudders, fans, friends, family, videographers and volunteers gather at the finish line, hooting and ringing cowbells, craning to see who’ll round the last corner and enter the stadium first. It’s Pak, stretching his lead over Boone at the end. He waves, bends at the waist, catches his breath as a volunteer with a garden hose pats him on the back, then rinses him off.

Boone jogs in nine minutes later. The two hug and pose for pictures. Pak’s official margin of victory, eight minutes and 56 seconds, represents six tenths of one percent of the race. Boone had him running scared.

As men’s and women’s champions they win $15,000 apiece. But it’s Pak who’s called to the winner’s platform to shake hands with founders Dean and Livingstone, to be presented to the crowd as “the toughest human being on this planet!”

“Maybe next year,” Boone says.

Other mudders are still out there, struggling toward the stadium. At one end of the course Scotland’s Fuddy Muckers trudge toward Electric Eel. Pak rolled through the mud to save time here, but the wheezing Scotsmen are long past technique. When one catches a sparking wire inside a nostril, Stirrat laughs his semicoherent butt off. “We’ve done many a fitness race,” he says, “but nothing beats this for awesomeness.”

Two weeks later a regional Tough Mudder south of Tampa caused a 10-mile traffic jam outside the venue. Dozens of mudders jumped out of their cars and—why not?—jogged the last few miles to the starting line.

Three years in, Tough Mudder was looking less like a sport and more like a community. Less like a brand, more like a cause.

One mudder motorist got stopped for speeding after the Florida event. “I was wearing my orange headband with pride,” Jim Redmond posted on Tough Mudder’s Facebook page. The cop who pulled Redmond over demanded his license and registration, and noticed his Tough ­Mudder headband. “You run the Tough Mudder?” he asked.

“Sure did,” Redmond said.

The officer returned to his cruiser. When he came back he was wearing an orange headband of his own.

“Slow down, mudder,” he said. He gave Redmond a fist bump and sent him on his way.