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Welcome to The Show! On Thursday, we won't be running a marathon to catch up with him, but we'll still be chatting with Ultramarathon Man Dean Karnazes.

Karnazes earned his moniker, the Ultramarathon Man, from his drive to run more than the regular marathon. Karnazes once overcame sleep for three nights as he ran 350 continuous miles. He's run a 200-mile relay race solo seven times and has moutain biked for 24 hours straight. In March 2006, Men's Fitness magazine said he "might just be the fittest man in the world." (After learning about the world's fittest man, check out our chat with the World's Strongest Man.)

So, what would be a test for the Ultramarathon Man? How about 50 marathons in 50 states in 50 straight days? That's right, Karnazes is in the midst of The North Face Endurance 50. He started Sept. 17 and he'll finish on Nov. 5. He started in St. Charles, Mo. with the Lewis & Clark Marathon and he'll end with the New York City Marathon, while hitting every state inbetween.

On Thursday, he'll be in Finchville, Ky. for the Otter Creek Marathon, race No. 40. He'll be joining us in chat after he's finished the race. In the mean time, check out his book "Ultramarathon Man: Confessions of an All-Night Runner."

Send in your questions now and join Dean for the answers on Thursday at 3:30 p.m. ET.

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