While Anderson is understated and under the radar, she is far from underqualified. Even before starting the Appalachian Trail, she had logged 15,000 miles in long-distance hiking. She had conquered hiking’s triple crown — the Appalachian, the Pacific Crest and the Continental Divide Trails — and in 2013 she hiked the 2,663-mile Pacific Crest Trail for a second time, setting the self-supported record on it.

When she completed that hike, in 60 days 17 hours 12 minutes, an average of 44 miles a day, she dethroned Scott Williamson, who had completed the Pacific Crest Trail 13 times and set numerous records on it. Williamson had logged more than 47,000 miles in long-distance hiking. Most F.K.T. followers assumed that Williamson’s trail knowledge, athletic prowess and determination were insurmountable. Then Anderson broke his record by four days.

Over the summer, when Anderson tackled the self-supported record on the Appalachian Trail, she was once again taking on a titan in the F.K.T. field. Matt Kirk had set numerous trail records in the Southeast, and when he broke the Appalachian Trail’s self-supported record in 2013, it was the first time the mark had been lowered in 20 years. Then Anderson broke his relatively new record by four days. Four days.

Anderson said that part of her confidence in going after the record stemmed from her personal observation of male and female hikers at the end of a long-distance trail. “Women appear to be better suited for walking long distances because it doesn’t seem to take the same physical toll on their bodies,” she said. “The women I see at the end of a long-distance hike look fit and badass, but the guys look emaciated.”

Still, Anderson hesitated to speculate whether women truly have an advantage over men in ultra-endurance events. “I believe that endurance is most likely genderless,” she said. “As a species we evolved by traveling long distances and carrying what we needed. It’s a human trait.”

Samuel Cheuvront, a research physiologist for the United States Army Research Institute of Environmental Medicine, agreed. “I can’t think of any reason why men would have an advantage over women at these lengths,” he said. “At distances over 2,000 miles, you are negating the benefit that males have due to increased muscle mass and aerobic capacity.”

Cheuvront was quick to point out that in long-distance swimming events measuring more than 20 kilometers, women consistently outperform men. In part, this is based on the increased buoyancy that women have, which comes from a higher body fat percentage.