50 marathons in 50 days

LOS ANGELES - Dean Karnazes insists he's not crazy. He just loves to run. A lot.

This Autumn, the 43-year-old long distance runner will tackle one marathon a day for 50 consecutive days, running a total 1,310 miles in 50 days. And for each 26.2-mile race, Karnazes and his family of four will travel to a different U.S. state.

Arguably the world's best-known ultramarathoner, Karnazes has already run 350 miles in one stretch, run a marathon in the South Pole, and raced across the California desert in the middle of the summer.

With this fall's challenge, however, Karnazes said on Tuesday he is going a step further in testing the human body's limits.

"I'm curious to see what the limits of human endurance are," he said in an interview. "I still haven't found them."

To train, Karnazes said he logs anywhere from 80 to 175 miles of running a week around his home in San Francisco. He has also picked up the pace of his racing schedule in the last five months, averaging about two marathons a month in addition to a range of ultramarathons, or distances longer than 26.2 miles. This week, he'll tackle a 100-mile race in Colorado.

"It's almost like designing an engine that can go 200 miles an hour for a 100-mile-an-hour race," Karnazes said of his aggressive training regimen, adding that he averages about four hours of sleep a night so that running does not get in the way of spending time with his two children, Nicholas, 8, and Alexandria, 11.

Beginning September 17 with the Lewis & Clark Marathon in St. Charles, Missouri, Karnazes' so-called "Endurance 50" event will take him to 8 official marathons and 42 "re-created" marathons across the United States.

Each marathon is expected to take around three-and-a-half to four hours, Karnazes said.

Runners of any ability are encouraged to join Karnazes along the way and can sign up online at the event's Web site, or read more on his blog.

Karnazes will end his quest with the ING New York City Marathon on November 5.

"I might actually log a couple extra miles," he said, adding that the logistics of getting from race to race are almost more challenging than the running itself.

Still, Karnazes insists that he's not crazy and that anyone could undertake the types of physical challenges he has.

"I've had a couple of jaws drop," he said. "I really don't consider myself to be gifted in any sort of way ... I just really love to run."