Ultramarathoner Scott Jurek began an attempt to break the supported Appalachian Trail speed record Tuesday, starting at Springer Mountain in Georgia with the goal to reach the summit of Mount Katahdin in Maine by July 6.

The current world record for the 2,168.1-mile route, set by Jennifer Pharr Davis in 2011, is 46 days, 11 hours, and 20 minutes. Jurek’s itinerary has him completing the trek in 42 days.

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"I am at the perfect point in my career and this has been on my bucket list for a while," Jurek said. He spoke with Runner's World Newswire Thursday evening by phone while on the trail near the Rock Gap shelter in North Carolina. "This is the summer before my wife and I want to have kids so I am pretty close to my retirement. I would say this is going to be my masterpiece."

Over the past decade, Jurek has been considered one of the best ultramarathoners in the world. His résumé includes seven consecutive Western States Endurance Run wins, two Badwater Ultramarathon wins, and a key role in Christopher McDougall’s Born to Run.

Despite these accomplishments, Jurek said this latest endeavor may be his most challenging yet. He will have to average more than 50 miles a day over highly technical and hilly trails. On Thursday he gained more than 13,000 feet in elevation over 53 miles. The section took him more than13 hours.

"I would say this is definitely the biggest adventure in my career, just in terms of the day in and day out," he said. "It's mind boggling a little bit. I have never done 350 mile weeks which I will have to do now."

Other world-class ultrarunners have tried and failed to achieve the same record, including Karl Meltzer, who despite having more 100-mile race wins than any other runner, dropped out of a supported attempt in 2014.

"We aren’t even in the really rugged stuff; Georgia and North Carolina are just relentless," he said. "But I know my body really well, I am really confident too. I know how my body adapts and I take care of it."

Jurek is documenting the attempt on Instagram and says he will provide a live tracker to follow his progress.

Kit Fox Special Projects Editor Kit has been a health, fitness, and running journalist for the past five years.

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