NEITHER OF THEM HAD WON. While Karnazes stood with his sponsors posing and hugging, the race's victor, a sweet, skinny 31-year-old named Scott Jurek, lay wrapped in a sleeping bag, tethered to an IV. Jurek is Western States' Lance Armstrong: He's won the thing seven years in a row, setting an astounding course record of 15 hours 36 minutes in 2004. After his 2005 win, he gave a short interview to a local TV station, then threw up. What's that about?

First, you need to understand that Jurek's obscurity is not only typical; it's standard, part of the sport's unspoken code of modesty, humility, and silent suffering. Up until recently, there's been no fame or glory for ultrarunning, which shows little sign of becoming a mass phenomenon. Last year, 12,000 to 15,000 people finished an ultra in the U.S., compared with some 150,000 triathletes and 423,000 marathoners. Fewer than 20 runners participated in all four races of ultra's trail-running grand slam: Western States, Colorado's Leadville 100, the Vermont 100, and Utah's Wasatch 100.

Ultrarunning is bigger internationally, but it's still such an underfunded addition to

"I would never discount what Pam's done," says Karnazes, "but it seemed kind of contrived. As in every ultra, I just compete against myself." Then he adds: "I gotta say, though, I think her ego's bigger than mine."

the global roster of sports—the International Association of Ultrarunners' 24-hour world championship has been held regularly for only the last three years—that members of the U.S. team, to which both Karnazes and Reed belong, had to pay their way to the July 2005 race in Austria. While triathlon is now an Olympic sport, ultrarunning probably never will be, since nobody wants to see the marathon, being ancient and Greek and all, getting upstaged. And because ultramarathons are not exactly spectator-friendly—who wants to watch a bunch of endlessly running runners endlessly running some more?—there's barely any TV coverage or big money in the game.

The sport's figurehead in this country is Marshall Ulrich, a 54-year-old veteran of 111 ultras, including 13 Badwaters (which he won four times). Ulrich has a reputation for suffering some of the best hallucinations in ultra lore—chasing a silver-bikini-clad siren through the desert and watching Mount Whitney squirm violently with millions of lizards. He's climbed the Seven Summits and competed in nine Eco-Challenges, and he's appeared on Dateline and the Today show. But he gets nowhere near the exposure of Karnazes.

Ulrich and Jurek aren't the only ones achieving great things under the radar. Few Americans have heard of ultra's greatest living star, Yiannis Kouros, a Greek racer living in Australia. In addition to breaking records in almost every road or track ultra event—from 24- and 48-hour races to 100-mile competitions—he ran 300 track miles in 60 hours in 1984, did 1,000 miles in ten days in 1988, and still competes at age 49.

And no one paid attention when John Geesler, a 46-year-old maintenance man from St. Johnsville, New York, ran 300 miles in 69 hours on a track a few months before Pam Reed's long solo. No official records are kept for three-day races, so it didn't make a splash, and Geesler didn't think to seek one. "Right after I did that race, I heard Dean was on the cover of Runner's World," Geesler says. "It's a coincidence that he's getting all this publicity for wanting to do 300 miles when I had just done it. Maybe it doesn't count in their eyes because I took a one-hour nap. That's OK with me. To each his own."

Geesler's next goal is to break the U.S. track record of 554 miles over six days. Even if he pulls that off, it's unlikely to make prime time.

So why do it? Because other people can't, and because there just may be something deep inside the human animal—or at least some human animals—that hungers to run this far. According to a paper published last year in the journal Nature, humans may have evolved to a higher plane specifically because of our predilection for running. Bipedalism, sweating, and springy tendons like the Achilles are handy for walking, the theory goes, but critical for running long distances. Two million years ago, endurance may have allowed our ancestors to run prey to exhaustion. Eating more fat and protein, we could develop smaller guts and larger brains. Running is us.

"People think we're crazy and psychotic and bizarre, and yes, some of us are very Type A or competitive," says Jurek, "but there's a spiritual side, too. You really learn about yourself when you bring yourself to that edge. It gives you a glimpse of what you're really made of and even the meaning of life, a vision of the soul. It's an evolved, instinctual thing to do."

Although Jurek does receive a modest sponsorship salary from Brooks running shoes, in addition to his job as a physical therapist, he hasn't written a book or graced a box of cereal. That suits him fine. I caught up with him the day before Western States. He was busy whipping up avocado-and-algae pudding and happily staying out of the spotlight.

"I think I'll pass on Dean Karnazes's image," he said. Like many runners, he finds the Pam-and-Dean rivalry annoying.

"To have this little sideshow going on," he said, "I don't think that's the essence of the sport."