Meet ultrarunner Courtney Dauwalter, the woman who outruns the men

Courtney Dauwalter specialises in extremely long races. But her success in winning them has opened a debate about how men's innate strength advantages apply to endurance sports

At 1:40 in the morning, running through the woods near Lake Tahoe, Courtney Dauwalter began hallucinating. She saw live puppets playing on a swing set on the side of the trail. Trees and rocks turned into faces. She was on her second night without sleep, 165 miles into a 205-mile race through the mountains, pushing her body to levels considered physically impossible not long ago, and seeing very strange things in the night.

Dauwalter had been on her feet for almost 40 hours and was leading the field of 215 runners as she set her sights on a course record