If you were overserved on your 30th birthday, as was Dean Karnazes, the idea of running 100 miles might have seemed entirely sensible at the time. That night Karnazes decided to run himself sober, and about 30 miles later, he was. Since then, he has dumped the cocktails and extended the mileage, but there's no easy explanation for what compelled him to run 262 miles over 75 hours, which seems to be the farthest anyone has ever gone in one shot; or to run the 199-mile Relay, a 12-man team race, solo.
Karnazes, 42, who now plans to go 300 miles nonstop, lays claim in his lively new autobiography, Ultramarathon Man, which will be published next month, to being the ultra of the ultramarathoners. That is a cultish group of athletes, many in their 40s, for whom a marathon just isn't challenging or interesting enough. If 36,000 people finished the New York City Marathon last year, how hard could it be? The ultras race over hill and dale in 50- to 100-mile painfests, like the Western States 100 and the Leadville Trail 100. Says John Medinger, 54, an investment banker in San Francisco who has run about 130 ultras: "If you think of the whole thing, it's scary, even if you've done it before. But if you break it into pieces or stay focused on the moment, it's entirely doable."
There's doable, and there's 300 miles, roughly the distance from Pittsburgh to Philadelphia. The Karnazes megamarathon will require staying up for more than three days, not to mention the possibility of sleep running and hallucinating. "My curiosity is how far this human system can go," says Karnazes. "What is it really capable of?" His endurance is legendary in the ultramarathon community, a 12,000- to 15,000-strong collection of rabid overachievers. On the road to 300 Karnazes pursues a vampire-like training schedule, rising at 2 a.m. for 50-mile runs and then putting in a full day at his natural-food business. The night runs also allow him to keep some semblance of daily family life with his wife and two children, who accompany him to races in the Mother Ship, a VW camper van.
People who run distances they ought to be driving aren't necessarily superior athletes. They are actually a bit freaky physically, born with the kind of biomechanics that can take repeated pounding. At 5-ft. 9-in. and 155 lbs., Karnazes isn't built like those marathon beanpoles. His frame is rock solid, the result of a cross-training routine that includes windsurfing to build upper-body strength, which helps him in the long runs. But even with the right genes and conditioning, ultras can count on plenty of joint pain, cramps, exhaustion and vomiting.
The ultra universe has another twist: women have a physical advantage. Pamela Reed whipped Karnazes to win the 2003 Badwater Ultramarathon, a 146-mile annual jaunt through the furnace of Death Valley, Calif., that ends more than halfway up Mount Whitney and reduces many ultras to roadkill. "It isn't the power that comes into play, it's your ability to go long distance. That's where the curves get closer together," says Dr. Lewis Maharam, medical director of the New York City Marathon. Ultramarathoners eventually burn fat, and women have a higher percentage of body fat than men do, giving them more endurance. They also benefit from the hormone estrogen, which may act like an antioxidant, protecting their muscles from breakdown.