Three things you need to know right away about Tony Krupicka:

First, the guy loves to run. Loves it. He cruises the trails above Colorado Springs three, four, even six hours a day, in all kinds of weather. He runs up and down mountains with more joy and less discernible effort than the average suburbanite waddling to the driveway to fetch the newspaper.

Second, this isn't a passing fancy. Now 24, Krupicka ran his first marathon when he was twelve. He's since racked up close to 40,000 miles, all of it meticulously recorded in his journals or his blog. Last year he ran 5,412 miles, for an average of 104 miles a week — but that's not quite right, since he was sidelined for almost five months of 2007 with two major injuries. When healthy, he averages 180 miles a week.

Third, it's a tricky business, pushing the human body beyond accepted limits of endurance. Hard-core distance runners say it isn't about competition or breaking records — and yet it is. For all his mileage, Krupicka didn't discover what he was capable of, or just how miserable he could feel, until he entered his first 100-mile race two summers ago.

"The best move," Norman Mailer observed, "can lie very close to the worst move." Mailer was writing about boxing, but he might as well have been peering into the sinewy heart of ultrarunning, a refuge for compulsives and crazies as well as superbly conditioned athletes. It's a world where what seems quite wrong to most people works brilliantly for others, and where young, fast talents like Krupicka are changing the rules of the game.

Audacity can take you to triumph or disaster, or maybe a bit of both. Krupicka's own dark night of the soul came in August 2006, in the final stages of his first Leadville Trail 100, a grueling high-altitude trail race from the center of Leadville to the ghost town of Winfield fifty miles away — and back again. Krupicka breezed past everyone all the way to Winfield; just a month earlier, he'd won a 50K that covered a portion of the same route. On the way back, though, he began to falter. Around mile eighty, while ascending 11,000-foot Sugarloaf Pass for the second time, something inside of him just crashed.

He had no strength. It was as if the gods had swooped down and stolen it. He slowed to a walk, then to a shuffle. Every step seemed incredibly labored and painful. His bowels were screaming for relief. Word was that Steve Peterson, a five-time Leadville winner, was only twenty minutes behind him. He told himself that maybe this was it, maybe he would just have to crawl the remaining twenty miles. Inside his head, the negotiations began.

"It was the worst I ever felt," he recalls. "When you're that low — no power, no energy — just walking is really hard."

Julian Boggs, a member of Krupicka's crew for that race, remembers that he was "barely coherent" at that point. "I've never seen anybody on the brink of death, but he seemed really awful," he says. "This was just a different level of exhaustion than anything I've ever experienced. A complete breakdown."

Krupicka kept inching forward. Much later, he would write of reaching deep down inside himself and finding a "raw, primitive and unadulterated portion of my being" that stubbornly refused to give up. He staggered up the pass and began the descent, finally reaching the kind of varied trail running he likes best. After five miles, he was jogging again. It was as if some hidden reserve tank had kicked in. His body was more resilient than even he suspected — and, as it turned out, Peterson was actually an hour behind.

"I felt great the last fifteen miles," Krupicka says. "To hit a low point like that and then recover from it is just amazing. A lot of people like to look at ultrarunning like that, as a metaphor for life."

Krupicka won the Leadville 100 in just over 17 hours, the second-fastest time the course had ever seen. Last year he went back and won it again, cutting his time by 47 minutes. Since he graduated from Colorado College two years ago, he's finished first in eleven out of twelve races he's entered, including the Rocky Raccoon 100 in Texas. (In the one race he didn't finish, the Greenland 50K, he dropped out because of injury while still in the lead.) He's set course records in the Estes Park and American Discovery Trail marathons and the Collegiate Peaks 50-miler. In February, he tied for first (by design) in the Moab Red Hot 50K+ with roommate and training buddy Kyle Skaggs.

His emergence as an ultra phenom has caught the attention of the small cadre of publications that cover the sport. Running Times recently dubbed him "Tarzan of the Plains" because of his penchant for running shirtless, long hair whipping in the wind, as well as his earnest talk about shunning technology and reconnecting with the land. "People like to make these runners out as characters," notes Adam Chase, the Boulder-based writer of that article and co-author of The Ultimate Guide to Trail Running. "Tony, I think, is genuinely a character. And he's very firm in his beliefs without being cocky."

Krupicka is also gracious, nerdy, thoughtful and shy. But he can be blunt, and some of his remarks have stirred up a surprising degree of resentment. When he told one interviewer that many ultrarunners "are woefully underprepared for an undertaking as daunting as a 100-mile run," the running blogs lit up with snarking about his nature-boy persona, his frugal lifestyle, his surreal training schedule — the general drift being, this is one brash young gun who clearly doesn't have to work for a living (he works part-time in a Colorado Springs running-shoe store), can't possibly sustain the kind of punishing mileage he cranks out every week, and won't be around much longer.

Such comments reflect a larger upheaval in the sport, Chase says. The ultrarunning scene has long been dominated by veterans, their bodies tempered by years of running marathons, but that's changing as younger competitors, oozing post-adolescent angst and in search of suffering and glory, are making their presence felt.

"Tony is kind of a lightning rod," Chase says. "The age group has shifted downward. I started in earnest in my late twenties, and that was considered really young back then. Now there are 21-year-olds showing up and doing even the hundred-milers — and kicking ass. A lot of these people haven't even run marathons. They were enticed by the extreme nature of this."

Krupicka doesn't see what the fuss is about. "A lot of ultrarunners are middle-aged professionals who have a lot of money," he says. "To them, it's a hobby. They have jobs, so of course they're not going to do 200 miles a week. That's fine. But I've chosen this way to live my life."

His choice has come at a price, including a dozen stress fractures and other injuries that have left him idle — and frustrated — for long, depressing weeks or months. Devoting so much time to running, Krupicka admits, has also put some strains on personal relationships and career plans. Last fall, after a stab at graduate school in Montana and another crippling fracture, he returned to Colorado Springs determined to get healthy.

But since that dark period, Krupicka seems to be hitting his stride. Two fellow Colorado College graduates shot a scenic documentary capturing his training over five weeks last summer, Indulgence: 1000 Miles Under the Colorado Sky, which is now being marketed on DVD to the ski-and-bike-film audience. He recently signed a promising sponsorship deal with New Balance. He has his eye on a series of daunting races this summer, including the Western States Endurance Run in California in June — one of the oldest and most respected hundred-milers, which usually attracts a deep field. It could be his chance to finally go head-to-head with some of his all-time heroes, veterans like Scott Jurek (who won WSER seven years in a row) and Matt Carpenter (who set the course record at Leadville in 2005, at the ripe old age of 41). And aside from a case of shin splints, he's been injury-free for months, possibly because he is seeking greater moderation in his training.

"I've matured physically and in my approach to running," he says. "I'm just not as obsessed about it. I train a lot, but I'll take an easy day here and there. I figured out that ten months at 150 miles a week is better than ten weeks at 200 miles a week, then getting hurt. If you can temper your obsession about it, in the end it's going to be better. It's important not to get too tied up in it, or it all falls apart."

Anton Krupicka sits in a booth at Wooglin's, a granola-tinged deli just off the Colorado College campus. He's not exactly eating the poppyseed muffin in front of him; he's deconstructing it, a few grains at a time. You might think that a man who's just run twenty miles this morning would be hungry, even ravenous, but not this man. Finally, another diner demands to know if there's something wrong with the muffin.

"It's a great muffin," Krupicka insists. "I'm just saving it for later. My metabolism is a little...different from most people's."

Even by the standards of college students, Krupicka is more than a little different. He majored in philosophy at CC. And physics. And returned a fifth year to pick up another degree in geology. He had a prestigious science scholarship on the first go-round but was looking to save money that fifth year, so he ended up crashing in odd places. He slept for months under the half-lofted dorm bed of Julian Boggs, a cross-country teammate; second semester he moved into the closet of another friend. Campus gossip about such exploits is probably how the Krupicka legend got started, the lurid tales of this stripped-down, super-freaky neo-hippie who lives on air, owns no furniture and runs barefoot across the West, seeking to inspire the masses to rise up against the evils of the Industrial Revolution.

There are, Krupicka acknowledges, some misperceptions about him floating around. His minimalist approach to running, for example. He doesn't go in for a lot of gear or even socks, but that's a matter of common sense, not affectation: Who needs the extra weight? Most of the time, he doesn't even carry water on runs of three hours or less, because he doesn't want his body screaming for hydration every few minutes. Yes, he runs barefoot sometimes, but not as much as people think. Okay, five miles barefoot last night on a flat path, but that was after 23 miles shod, and not because of some crazy Tarzan image he's trying to promote.

"It strengthens the feet," he insists. "It allows me to wear more minimal shoes, which just feel better. I'm not anti-technology. Just anti-gear."

It's true that the crash pad he shares with ultrarunner Kyle Skaggs has a certain paucity of furniture — futon, no frame. But that means there's less to haul around when it's time to relocate. He's also been known to camp out before a major race, and he spent the night before his first Leadville 100 in a public restroom. But he's hardly the only ultrarunner to practice thrift.

"A long time ago, I decided there was no point in renting a hotel room when I'm traveling," he says. "There's lots of places you can throw a sleeping bag. Sleeping on the ground isn't a big deal for me. If you don't think it's going to affect your performance, it won't."

On close analysis, much of what passes for Krupicka's fabled whole-grain nuttiness — his love of simplicity and natural foods and minimalism, his fervent scrimping, his disdain for overstimulated joggers chatting on cell phones or wired into their iPods — turns out to be closely allied with the values he learned as a child in the self-reliant, rustic northeast corner of Nebraska. "The way you're raised ends up shaping your worldview," he declares, "and the way you live is how you act that ethic out."

Krupicka grew up outside Niobrara, on a small family ranch on the bluffs of the Missouri River. His mother, Liz, is a high-school teacher; his father, Ron, for many years directed small-farm energy programs for the nonprofit Center for Rural Affairs. Tony and his two sisters helped with all the chores, including gardening and stocking the root cellar with a dozen different crops.

"It was a simpler lifestyle, focusing on sustainability and living off the land," explains Ron. "We had a big debate, my wife and I, over whether we were going to have a phone. We emphasized reading, and we'd go on a major trip every summer, camping and hiking."

The elder Krupicka remembers his young son sporting a Huck Finn hat and building forts in the woods with an ax he received for Christmas. Then he started running. "There were trails all over the farm," Ron recalls. "He'd use his ax to clear them. He was in cross-country mode at a very early age."

Running was just something he always felt good about, Tony Krupicka says. At eleven, he ran a mile faster than anyone in his class and began scouring thrift stores for running books and magazines. He found a copy of Run to the Top, by New Zealand coach Arthur Lydiard, which advocates 100-mile weeks for serious runners. He also found a magazine that mentioned a marathon held in Okoboji, Iowa, just a few hours' drive from home. After a little wheedling, his parents agreed to let him enter the event.

"When you're that age, it's kind of awkward," he says now. "You're trying to find your place in the world. Anything that gives you any kind of self-esteem, you're going to latch onto it."

By the time he was thirteen, he was running a hundred miles a week. He wasn't quite 5'3" and weighed less than a hundred pounds. Over the next few years, he sprouted like a weed — he's now six feet, 150 pounds — and tried to keep up the same pace, resulting in a series of stress fractures.

Ron remembers driving a 20-mile loop around the farm in a thunderstorm, trying to find his hard-charging son before a lightning bolt did. "He was obviously passionate about it," he says. "We had misgivings at first, but Tone could speak pretty eloquently about what it meant to him. I guess he convinced us that it was a good thing, that he could be doing a lot of worse things than running."

Krupicka's high school had no cross-country program; he convinced the school board to add one. But injuries and different ideas about training kept him the odd man out. The track coaches had their favorite events, and none of them involved the kind of distances he liked to run.

"I've never operated well under coaches," he says. "It's not like I have a problem with authority figures, but I always wanted to run the way I want to run. I was always injured or overtrained."

A similar pattern developed during his college years. He'd train hard in the summer, piling up the mileage, then have difficulty adjusting to the speed drills at school and post unremarkable numbers on cross-country races. The kind of interval training common in college track programs — running 400 meters or a mile, resting a couple minutes, then doing the same thing — didn't sit well with him. "He's actually a lot better at short distances than he makes out to be," says Boggs. "He just doesn't think his body can handle the training."

Krupicka made some lasting friendships among CC's cross-country stars; his girlfriend, Jocelyn Jenks, and Boggs, who still joins him on evening runs, are both seniors on the team this year. But he didn't blend in easily with the school's athletic community at large, what with his dim views about excessive partying and strong opinions about training and his chronic injuries. "He can be real abrasive and gruff," says Boggs. "I've certainly gotten pissed off at him and said he was stupid for running as much as he did. But what he does is hard; it takes a lot of self-control."

Frustration over his erratic cross-country performance didn't stop Krupicka from putting his college studies to good use, honing his notions about sustainability, environmental ethics and his own possible role in the world. He read avidly and widely. "The stuff that influences my running is the stuff that influenced my life," he says. "Reading Ed Abbey influenced my running more than Arthur Lydiard."

By his fifth, final year, he was making plans to try some ultra events as soon as he was out of school. In some ways, it was a postponed dream; as a kid running around Niobrara, he'd often wondered what it would be like to run for seventeen hours straight. He started pushing up his training mileage until it reached 200 miles a week. Shortly after graduation, he cruised to his first marathon and 50K wins. But he still didn't know if he was ready for the Leadville 100. "Everyone was just assuming I was going to do it, but I wasn't sure," he says.

John O'Neill, manager of the Colorado Running Company — the shoe store just off campus where Krupicka now works — remembers egging him on that summer during Wednesday-night group runs. "I just told him, 'Dude, you're running 200 miles a week,'" recalls O'Neill. "'You need to go up there and kick some ass.'"

After some hesitation, Krupicka did just that. Somewhere around mile eighty, an ultrarunner was born. Winning the race after coming so close to collapse on Sugarloaf Pass gave him a fleeting sense of invincibility, he says now.

"It kind of messed me up, actually," he says. "I got mono shortly after Leadville and didn't know I had it. I ran a marathon in Colorado Springs two weeks later and PR'd [set a personal record], but I felt terrible for months after that."

Not surprisingly, Krupicka couldn't run a lick the day after his first Leadville 100. The second time, in 2007, he kept a comfortable pace throughout, not pushing it, and still finished three-quarters of an hour sooner. "It was kind of a submaximal effort," he says. "I was ahead by three hours. When you're just jogging along, it's not going to feel so bad."

It was the easiest 100-miler he'd ever done. His body was much stronger and faster, his training much better. The next day he ran five miles, just to keep things in tune.

Krupicka agrees to a photo shoot on a ridgeline near the top of Mount Buckhorn, a brief interruption during his morning training run. The photographer and his assistant drive up North Cheyenne Canyon to the end of the paved road and park. They hike up a mile of dirt road, then half a mile of steep switchbacks. By the time they reach the rendezvous point, they are sucking down water and feeling the 8,000-foot elevation.

Their subject arrives right on time, having run twelve miles from his apartment in Colorado Springs, picking up 2,000 feet in elevation gain along the way. He isn't even breathing hard. He pauses, smiles for the camera — and is soon on his way back down the mountain.

As anyone knows who's seen clips of Indulgence on YouTube, there's a kind of ease and fluidity to Krupicka's trail running that makes even a well-conditioned jogger on a flat path seem ungainly. Distance running has a deeply seductive, meditative quality, and Krupicka says that's one of the things he loves most about it — the ability to be alone in the natural world, immersed in the sights, sounds and smells of the mountains, the rhythm of the run and his thoughts. During those long hours in the hills, he considers upcoming races and how he should approach them, playing out scenarios in his head; he reviews his training and his mistakes; and juggles Dostoyevskian questions about suffering, sacrifice and what happens next.

Lately he's been thinking a lot about balance, about the need to get a better handle on the highs and lows of his obsession. The last year or so has been a stomach-churning roller-coaster ride, and he's trying to make sure the track ahead is a little smoother.

Low: Being dogged by a gimpy knee that seriously cut into his training plans for Leadville. Fortunately, after weeks of misery, a sports-therapy clinic was able to figure out the problem — inflamed meniscus — and massage it back into place.

High: Springing back from injury to cram a thousand miles of tasty summer runs into five weeks in Colorado, Utah, Nevada and California — the odyssey depicted in Indulgence — and then smoking the field at Leadville.

Low: Arriving in Bozeman at the end of August to start graduate studies in geology at Montana State University and picking up a stress fracture almost immediately, the result of one wrong step on a little rock. He was in a boot and on crutches and didn't run again until Thanksgiving.

"It was the most depressed I've ever been in my life," says Krupicka. Hobbling around campus, he eventually decided to drop out of MSU and pursue another area of study, possibly environmental science.

Jenks, Krupicka's longtime girlfriend, says it's difficult sometimes to deal with the black funk that surrounds an injured Krupicka, but that's part of the whole package. "When he was in Montana and injured and I was here, I felt pretty helpless," she says. "But there's really an element of admiration you have to have for someone who has that much passion about something. It goes beyond dedication. So few people find something in their lives that they want as much as Tony wants to run. You have to be careful that it doesn't possess you, but it's really beautiful to have that experience."

High: Returning to Colorado Springs, spending downtime with Jenks, getting healthy again and retooling his training. Although he still does longer runs on the weekends, Krupicka has cut back on his daily regimen in recent months, typically running three hours instead of four or five, and feels better for it. "The difference in an hour a day is huge," he says. "It gives your body a chance to recover."

Low: Not getting selected in the lottery for the 2008 Western States Endurance Run.

Krupicka has unleashed more than one tirade on his blog about the rash of red tape, hefty fees and obtuse rules that are strangling his sport. Many 100-mile races cross public lands, whose stewards impose a strict cap on the size of the field — but the same events are becoming so popular that even elite runners are having a hard time getting into them. At the same time, the number of ultra races is proliferating, allowing some runners to cherrypick events where they're unlikely to face strong competition. The result is that head-to-head battles among the most serious athletes are uncommon, and inflated reputations abound.

Not that Krupicka has anything but admiration for the likes of Jurek or Carpenter. But most people have never heard of either one; they're more likely to have encountered the publicity machine of Dean Karnazes, author of the best-selling Ultramarathon Man and darling of the mainstream media (#27 in a Time list of the world's most influential people). Karnazes ran the Leadville 100 in 2006, but Krupicka didn't have much opportunity to get his autograph.

"Everyone asks me if I've ever heard of Dean Karnazes," Krupicka sighs. "I tell them, 'Yeah, and the one time I raced him, I beat him by seven hours.' I'd showered and was asleep by the time he finished."

Getting shut out of the Western States lottery forced Krupicka to seek another means of entry: the American River 50-Mile Endurance Run, from Sacramento to Auburn, California. The top three finishers in the AR50 qualify for Western States. The first 26 miles of the course is pavement, not exactly Krupicka's preferred terrain, but he has built more speed workouts on flat ground into his training to compensate.

"I'm feeling good," he reports, a few days before heading out to California. "It's not that cool a race. I'm looking forward to getting back to more trail running. But this is going to be one of the most competitive ultras I've run."

There's not a wealth of prize money in ultrarunning, and Ron Krupicka has been gently urging his son to focus on planning for a life beyond the races still to come. "It doesn't concern us too much that he hasn't gone out and got the job and the debt and the responsibilities of adulthood yet," the elder Krupicka says. "That will come soon enough. But I think he fully recognizes — and we've talked to him a lot about it — that this could be just a phase. Enjoy it, but that doesn't mean you don't make plans for the future, too.

"He's had numerous stress fractures, and the next one could make it not possible to do the things he's been doing. And what if you do measure up? Then what? You win a race, people pat you on the back and say, 'Way to go.' And then...that's it."

His friends say Krupicka would still be running 150 miles a week even if he wasn't racing. "Running a ton of miles can take a toll physically," says Skaggs, who's also been stomping course records in his budding ultra career. "But there's also the burnout factor. I don't think that's an issue if you really love what you're doing."

Jenks is thinking about law school, and she and Krupicka have had long, liberal-artsy discussions about whether it's better to try to change the world through direct action or live the life you want to live and hope to inspire by example. Krupicka hasn't figured out which way he wants to go yet. He just knows he wants to keep moving.

Last month he spent a week with Skaggs in the Gila Wilderness, a remarkably desolate, untouristed slice of desert in southwestern New Mexico. "We did a couple of five-hour runs, and days like those remind me that I have zero need to race," Krupicka says. "I'd still do this all the time. Obviously, I'm a competitive person, too. But there will be a point where I'm not competitive anymore, and I'm still going to be out there running."

Last Saturday he was in California, running hard. As he expected, the field for the American River 50-miler was deep and talented. It wasn't until the final twenty miles, after the pavement gave way to a single-track trail, that the long-haired kid from Colorado Springs began to pull away. He finished in five hours and 42 minutes, a quarter-hour ahead of the nearest challenger.

It was, he says, "pretty much where I thought I could be" — in first, with the Western States race looming in June, and miles and miles to run between now and then.