Scott Jurek has been eyeing the Appalachian Trail for years. On Wednesday May, 27 at 5:56 a.m., he began his pursuit of the the trail’s speed record.

Jurek has won nearly all of ultrarunning’s elite events, including the historic 153-mile Spartathlon, the Hardrock 100, the Badwater 135-mile Ultramarathon, the Miwok 100K, and—his signature race—the Western States 100 Mile Endurance Run, which he won a record seven straight times. In 2010, he set a new US all-surface record in the 24-Hour Run with 165.7 miles—6.5 marathons in one day.

Jurek was a central character in Christopher McDougall’s bestselling book Born to Run. Jurek ran alongside the Tarahumara runners in the Copper Canyon Ultra and later won the event.

Now 41 years old, Jurek has set his sights on the ultimate ultra prize: the Appalachian Trail speed title. Asheville’s Jennifer Pharr Davis holds the current A.T. speed record of 46 days, 11 hours, 20 minutes, which she set in 2011. Davis averaged 47 miles per day and was supported by her husband, Brew Davis, as well as legendary trail runner David Horton and sixteen-time A.T. thru-hiker Warren Doyle.

Jurek is trekking northbound on the A.T. and will be passing through Georgia, Tennessee, North Carolina, and Virginia in the next three weeks. He hopes to arrive atop Katahdin by early July.

Blue Ridge Outdoors editor in chief Will Harlan will be joining Scott Jurek for part of his Appalachian Trail trek. Look for his reports from the trail at blueridgeoutdoors.com.