Corey Rich, courtesy of The North Face
	Dean Karnazes, perhaps the world's top ultramarathoner.
	A look at the Endurance 50, in .pdf format. To view the file, you must have Adobe Acrobat Reader, available as a free download from Adobe
	John Cosetello, Philadelphia Inquirer
	Dean Karnazes, center in white shirt, begins his 48th marathon Friday running with supporters on the Benjamin Franklin Parkway in Philadelphia.

GRAND RAPIDS, Mich.-- Dean Karnazes stood on a street corner, 748 feet above sea level and, perhaps, a hopeless distance below the sanity line. All these other runners, maybe 75 of them, stood shivering, rubbing their upper thighs, second-guessing their motives. They'd come to this spot because of Mr. Karnazes, one of the world's top endurance athletes. And soon, they'd all run 26.2 miles through parts of a city that felt like a grocery store freezer section, but with less scenery.

The whole scene begged a big why? After all, everybody wants the why the first time they hear about Mr. Karnazes' mission. He's attempting to run 50 marathons in 50 states on 50 consecutive mornings. He's finishing today with the New York City Marathon. He ran in Philadelphia (No. 48) on Friday. A day before Grand Rapids (No. 35), he chugged out 26.2 in Cleveland on two hours sleep. A day before that, he'd finished Vermont and driven 620 miles to the next spot.

Mr. Karnazes, 44, has tried to explain how he loves the perspective this has allowed him.

But before we worry about seeing his logic, let's allow the sun to rise.

The Grand Rapids race began much like the others. The casual runners, those who'd paid the $100 marathon entrance fee, arrived first. Then the ultra-runner arrived, the man who'd written a bestselling autobiography, translated into 11 languages, and who, one year before, had prompted an eruption of attention within the often-obscure endurance sports world when he ran 350 miles straight, fighting hallucination. He ran for 80 hours, 44 minutes. Then he stopped, and eyed his next project: The Endurance 50, he called it.

Because few cities hold their marathons on weekdays, Mr. Karnazes and his team of coordinators had to re-create 42 of the races, with help from directors and police forces in every town. (He's also participating in eight "live" marathons.) Mr. Karnazes hoped amateur runners would join him at the various starting lines. That way, he could spread his zeal, town by town, like a Pied Piper, albeit one with veins the size of green beans and quad muscles shaped like turbines. Mr. Karnazes, from San Francisco, began the Endurance 50 on Sept. 17 in Missouri. He's learned, in the passing weeks, the contagiousness of a runner's insanity.

"With the initial conception of this idea," Mr. Karnazes said, "I was just going to cross the state line and [measure out] 26.2 miles. But, hey, then it was like, 'Don't do this in a vacuum. Let's bring people together.' Since then, it's been surreal. To show up to Fargo and have 30 people there on a random Wednesday, I mean, do any of these people work? There are all these people there, ready to run a marathon. Inspiration is a two-way street, because so many people say that what I do inspires them. It's like, no, I hear your stories and it inspires me."

Before the Grand Rapids race began, Mr. Karnazes requested a group photo, one that he'd post hours later on his blog, updated regularly; his tour bus is outfitted with wireless Internet. A representative of apparel company The North Face, which sponsors Mr. Karnazes and his tour, grabbed a digital camera. But later, when runners checked out the photo, they saw only faint traces of lean bodies, all sharing the same pre-dawn darkness and obscured by reflective flashes from dozens of Asics.

At the starting line, Mr. Karnazes explained his informal suggestions. Take it easy, he said. Run as a group. Keep a comfortable pace, maybe 9:30 for a mile. He asked that the quicker runners in the group hold back. He asked that the newer runners simply try their hardest. And, by extension, Mr. Karnazes, for the 35th morning in a row, changed a few basic things about running.

It's a sport that, for most, necessitates the fight with solitude. A human in motion thinks about the cranking knees, the time on the stopwatch, the dripping sweat; the knees, the time, the sweat, on repeat. The Larry King episode, playing on that television set in front of the gym treadmill, barely registers. But Mr. Karnazes attempts to invert running's very nature. He wants one group immersed in conversation, at least for as long as they can manage. Communal agony, he figures, trumps agony alone.

When Mr. Karnazes, speaking before the Grand Rapids marathon, recounted his adventure, he began with the stories he's heard. He's run beside ex-smokers, ex-drinkers, college students joined by their parents, a person who'd flown in from Italy and a Japanese man who'd joined him in Hawaii, rearranging his wedding plans to make it work.

By the time Mr. Karnazes reached Grand Rapids, he'd learned something about running. The simple, shared goal of two strangers, running side by side, could unite them. During marathon No. 35, Mr. Karnazes met a woman, Amy Dobson, who'd lost her left leg to cancer and ran with a prosthetic. A carload of guys from Nebraska had driven through the night to run there. A 24-year-old schoolteacher, while running, told Mr. Karnazes how his book had prompted him to begin training for marathons.

"I've created a monster," Mr. Karnazes told the runner. "Um ... in a good way."

Even when running, say, near mile 24, Mr. Karnazes looks about as fresh as somebody who's just taken the elevator to work. He barely sweats. He consumes between 5,000 and 6,000 calories a day, and one of the trainers traveling state to state said Mr. Karnazes' body, two-thirds of the way through the Endurance 50, showed the muscular deterioration of someone who'd run one half-marathon.

The capacity for such endurance is born more from practice than natural gifts. Fourteen years ago, Mr. Karnazes says, he earned a six-figure salary working for a major health-care company in San Francisco. On his 30th birthday, during a night of drinking with friends, his tolerance for that lifestyle snapped. He left the party, grabbed an old pair of sneakers and started running, no time for the why. Thirty miles and seven hours later, he found a pay phone, called his wife and asked her to pick him up.

Since then, he's become the face of ultramarathoning, in part because his chiseled face and engaging personality open the door for exposure. He won the 2004 Badwater Ultramarathon, a 135-mile race through Death Valley that melts runners' shoes. He's run a marathon near the South Pole. He's spoken about eventually completing a 500-mile run.

"So with [the Endurance 50], it's different," Mr. Karnazes said. "This is more calculated, more tactical. Some of the other runs I do are just one single grunt, so you try to figure out how to cross the finish line completely spent. With this, I'm trying to cross the finish line with some reserve, not just physically."

The last weeks have altered his perspective. During his run in South Dakota, he spotted turkeys and white-tailed deer. He saw moose and snow-covered mountains in Alaska. He persisted through 104-degree heat in Arizona, and driving rain in Texas. Like this, he's moved through America, depending largely on salmon and energy bars for recovery.

Running experts suggest that Mr. Karnazes benefits from perfect footwork, minimizing effects of the mileage. He moves with a short, purposeful stride. On group-run marathons, he, and everybody else, crosses the finish line somewhere after 4¹/₂ hours. During "live" marathons, such as today's in New York, Mr. Karnazes can finish in 3¹/₂ hours.

In Grand Rapids, Mr. Karnazes' daughter, wearing a winter jacket, shouted the words that sent the pack running through the dim city streets. The group trekked over railroad tracks, past the dilapidated houses on Wealthy Street, past the car impoundment center, past a lengthy path in a wheat field, past the loop through Millennium Park, past the halfway point, past the suburban towns, past the point where they, excluding Mr. Karnazes, saw the wisdom of continuing. Yet they continued.

"My longest training run before this ordeal was about nine miles," said Greg Russell, the department chair of political science at the University of Oklahoma, who ran with Mr. Karnazes in Tulsa. "So I did not train properly for this thing. But it never occurred to me to stop, though the body was struggling in various ways. And the odd thing was a kind of euphoria amid the pain.

"The struggle forces you to ask tough questions of yourself, to wonder what you are capable of doing, to know that there is a reservoir of physical and mental strength that we seldom tap and use in good and decent ways. At the end of the day, it was a thrill to shake [Mr. Karnazes'] hand and stand together, in mind and spirit, at the end of a journey."