Ultrarunner Scott Jurek’s attempt at the fastest known time on the Appalachian Trail may be his last run as a pro. “Scott considers this run to be his ‘masterpiece’ and has talked of retiring from competitive running once this attempt is complete,” according to a June 25 press release from his sponsor, Ultimate Direction. His wife, Jenny Jurek, confirmed to Outside in a text message from the trail that this is true. “Yes, he might officially retire from racing after this, although he will always run and do races for fun,” she wrote.

Jurek, who was featured in the bestselling book Born to Run, is one of the best ultrarunners of all time, with seven consecutive Western States Endurance Run wins and two Badwater Ultramarathon wins. He’s presently on track to set a new world record for a supported thru-hike of the 2,185-mile Appalachian Trail. The current record, set by Jennifer Pharr Davis in 2011, stands at 46 days, 11 hours, and 20 minutes. Jurek is on track to finish in just 42 days, on July 7.