For most hikers, attempting to walk the length of the Appalachian Trail is an exercise in failure. Of the roughly 3,000 individuals each year who try the “thru-hike” – walking the trail’s entire length in one trip – 75% will not complete the journey. This dropout rate is understandable. The trail’s epic scale gives low-probability risks ample room to transform into unsolvable problems.

The trail, which spans much of the eastern United States, stretches 2,190-miles (3,524 km) across the Appalachian Mountains and through 14 US states, much of it in wilderness. Among those who successfully thru-hike the route from Maine to Georgia (or vice versa), most will need five to seven months to complete the trip. But American ultrarunner Tara Dower is no ordinary hiker. In September, she set a new speed record on the Appalachian Trail, finishing her thru-hike in just under 41 days, beating the previous record by 13 hours. Covering such a distance in that span required Dower to run the equivalent of more than two marathons each day – over mountains. Speaking with the Guardian a few weeks after finishing her record-setting run, Dower could still feel every step.

“I’m tired,” she admits. “I tried to run the other day and it was embarrassing. I ran for five seconds was like, ‘All right, I’m done.’” Dower regularly runs (and wins) 100 mile, single-day races, so her extreme fatigue is a testament to the challenges the trail poses to runners chasing speed records. Despite her accomplished career in elite ultrarunning, however, Dower also knows the pain that the Appalachian Trail can inflict – seven years ago, she was one of the 75% of people unable to complete their thru-hike.

“2017 is really where it began,” she says. “And, [it] didn’t go quite the way I wanted it to.” After years of completing small sections of the trail, she experienced a panic attack just eight days into her first planned thru-hike.

“I didn’t process fully what that would look like, physically [and] mentally … It was a change to the system. To go from the comfort of a home and the comfort of showers and a bed,” Dower says. “At the time, I didn’t know what it was. I didn’t understand panic attacks – [they are] a very physical manifestation of anxiety. I felt like something was sitting on my chest … I didn’t really understand, at the time, how to deal with anxiety. I had just graduated college and, I guess, I just thought that ‘If you don’t think about it, it’ll be OK.’”

Dower says she was “devastated” after her first attempt, which raises the question of why she tried again. It is, perhaps, an unfair question – nobody grills Lionel Messi over his decision to play another match after a loss. At the same time, success in football doesn’t require days of sleep deprivation, weeks without showers, or many of the other myriad hardships endured by elite ultrarunners.

But Dower’s relationship with endurance sport is the product of three factors: a natural penchant for long-distance running, a lifelong affection for the Appalachians and, of unexpected importance, a Covid-related travel complication. Raised in the relatively flat suburbia of central North Carolina, Dower’s passion for sport started early but was directed away from the mountains.

“I grew up watching sports, I’m a Dallas Cowboys fan,” she says. “I played soccer throughout my life and ran [track and cross-country] in middle school and high school. I’m not one to stay still very often.” She went on to play rugby at college, where she studied sport and hoped to segue her degree into a career in the NFL.

“I wanted to do something with the Dallas Cowboys,” she says with a laugh. “I was just getting a degree in something that I enjoyed learning about and hoping that I could figure out, a little later, what I wanted.”

A chance viewing of a documentary about the Appalachian Trail, however, introduced Dower to a new subculture that caught her attention and, eventually, changed her life. Although she’d encountered the Appalachians during family trips, the culture of thru-hiking depicted in the film fascinated her.

“Just the act of walking from Georgia to Maine seemed really difficult and bizarre. Like, who does that? At the time, I never even knew that people even did that,” she says. “I was really intrigued by experience of the mountains, but I think I was more focused on the challenge of it.” Dower eventually decided that she too would attempt to thru-hike the full trail.

She took at a job at an outdoor shop where, among other things, she was able to buy discounted gear for her expedition – the same trip that ended with her panic attack.

“The panic attack really scared me,” she says. “It was really hard for me to see anything to do with the thru-hiking [in the future].” Eventually she would try the thru-hike again with her husband, Jonathan, in 2019. This time she was successful.

“We were on the trail as newlyweds,” Dower says. “I really peaked during that thru-hike in 2019 ... I still say that now, even after setting this [record]. Still, [2019] is the best experience of my life.”

With the Appalachian Trail finally under her belt, Dower decided to thru-hike another trail. She eventually landed on a 2020 journey along the Mountain-to-Sea Trail, a 1,100 mile path that runs from North Carolina’s mountains to the Atlantic coast. Like her 2019 thru-hike with Jonathan, Dower’s Mountain-to-Sea journey was initially intended to be a non-competitive, recreational trip. Then Covid happened.

Thru-hikers walking long distances often rely on pitstops in small towns to replenish their supplies. During Covid lockdowns, however, such interactions were discouraged. As a workaround, Dower asked people already in her “pandemic pod” to meet her with supplies along the way. In doing so, she realized that she was also inadvertently setting the conditions for a “supported fastest known time” attempt.

A quick explanation – attempts at a trail’s fastest known time (FKT) are where long-distance hikers can engage their competitive side. A database of FKT speed records, managed by Outside magazine, updates and verifies attempts daily, organizing them by several variables. Dower’s recent record, for example, was achieved while working with a team and travelling southward along the trail. In addition to setting the record in this specific category, Dower’s run is also the fastest overall Appalachian Trail thru-hike regardless of support-type or direction of travel.

Despite never attempting an FKT previously, Covid restrictions and helpful friends meant that Dower could easily adapt her pitstops on the Mountain-to-Sea Trail to maximise her efficiency. So, she decided to also attempt the FKT. Although inarguably a success – in the frequently updating world of FKTs, Dower still holds the Mountain-to-Sea Trail’s female FKT – it wasn’t enjoyable.

“It was a really difficult experience. I didn’t really know what I was doing. My crew – we weren’t really that well-versed in what we were doing, as far as nutrition and sleep deprivation. It was probably the hardest FKT I’ve done,” she says. “I couldn’t run for more than 10 seconds without feeling like I was going to fall over and faint … My brain was like scrambled eggs out there.”

Despite those difficulties, Dower’s interest in competitive sport was reignited and she was intrigued by the team dynamic of what is superficially an individual pursuit.

“Definitely in supported FKTs, I consider it a team sport,” she says, comparing her support team to a motorsport pit crew. “I am the physical racecar. I like to view Rascal [Dower’s support team leader] as the pit crew chief and the pacer with me at [any given] time is the driver of the racecar. Although I am moving my body, they are the ones leading me and feeding me. And then the ‘pit crew’ is fuelling me and maintaining my body and all I am is this physical manifestation of this FKT. I wish on [Outdoor’s FKT database] they would refer to it as a ‘team,’ rather than just my name.” Her experience on the Mountain-to-Sea Trail helped her finetune her team selection process for her Appalachian Trail FKT attempt.

“I look for people who know me really well,” she says. “They kind of push me a little harder and there’s no real sympathy there. It’s going to be hard and I’m probably going to cry and I probably am going to be injured or hurt. It’s just nice to have people there who are going to push you a little further.” The new strategy worked. Although Dower had won other races and set other FKTs in the time since her thru-hike on the Mountain-to-Sea Trail, her recent record on the Appalachian Trail clearly stands out.

“I think this is ‘mission accomplished.’ Even if I hold [the record] for a day,” she says. “This is just a more meaningful record … Not a lot of people have come close to beating the Appalachian Trail record.” She already knows of multiple men who plan on pursuing her record next season. It’s worth noting that Dower is the fastest person, male or female, to complete the Appalachian Trail. For her part, she hopes at least as many women attempt to break it as well.

“I would love to encourage more women to go for these long FKTs,” Dower says, “because I do think we have this special gift for endurance.” She is part of a broader trend in which female athletes outperform their male counterparts in ultra long-distance events. As anecdotal evidence, she mentions the widely made observation in the hiking community that men often seem emaciated at the end of a thru-hike, whereas women appear to be at peak fitness.

“I’m sure there’s somebody out there,” she says, “But I’ve yet to see a photo of a woman after her through-hike looking as starved as a man.”

Although generous with her thoughts about the future of Appalachian Trail FKTs, Dower is more guarded about predictions for her own career. Many peers have encouraged her to chase FKTs on other routes out west which, along with the Appalachian Trail, comprise the “American Triple Crown of Hiking.” She’s not ready to make such a decision. For the time being, she’s still processing (and recovering from) her time on the very trail that, just seven years ago, left her feeling devastated.

“When I did finally break [the Appalachian Trail record], and it was official and it was verified …” Dower momentarily loses her words, before concluding, “I was complete.”

• This article was amended on 15 November 2024. Tara Dower was running the trail southward, not northward, when she set the record.