Why Women are Running Stronger, Longer

Female bodies just might be built for the challenge of greater distance—as are our minds and hearts. Here, we dig into the science of endurance.


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Ellie Pell blazed across the finish line of the 2019 Green Lakes Endurance Run—a 50K trail race—in 3:58:37, nearly eight minutes ahead of second-place finisher Richard Ellsworth.

Race organizers were so surprised a woman bested the 90-athlete field they didn’t even have a trophy for the top male runner. Pell, then 27, carried home two wooden plaques bedecked with greenery, one for the overall winner and one for first-place female, while Ellsworth’s was custom-made and shipped to him later.

In some ways, you can’t blame the race directors. At nearly every distance from the 100 meters on up, the fastest women tend to finish behind the fastest men.

And though records of women swiftly covering significant ground appear in history—in 1,000 A.D., for instance, a Scottish slave named Hekja would reportedly run for days on end on missions from her master—modern times haven’t always offered them the opportunity to try. As recently as 1968, women were barred from running more than 800 meters in the Olympics, lest their reproductive organs tumble out or their frail bodies fall apart.

But from another perspective, Pell’s victory shouldn’t have come as a shock. Joan Benoit Samuelson claimed victory in the first Olympic Marathon in 1984, and women haven’t stopped pushing their limits since, including in distances that far exceed 26.2 miles.

As the sport of ultrarunning increases in popularity—according to a large study earlier this year by RunRepeat and the International Association of Ultrarunners, participation has exploded by a factor of more than 16 since 1996—more women than ever are claiming spots at the starting lines. Female athletes now make up 23 percent of the more than 600,000 ultrarunners annually, up from 14 percent in 1996.

And increasingly, women are finding themselves first to the finish. Ann Trason may be the pioneer of the trend: Back in 1989, she claimed the 24-Hour National Championship outright by logging 143 miles, about three and a half more than second-place finisher Scott Demaree. She twice finished second overall, beating all the men but one, in the 100-mile Western States Endurance Run, a prestigious event often called the Super Bowl of ultrarunning.

The mentality is so different now, and it gives room for women to push themselves harder, reach their full potential.

Then came Pam Reed, who in 2002 and 2003 crossed the line first at the Badwater 135, an arduous journey through Death Valley, California, in which temperatures often reach above 120 degrees Fahrenheit. Reed, now approaching her 60s, is still racing—against a new crop of runners eager to carry her torch forward.

Courtney Dauwalter has notched outright victories in everything from 24-hour races to 50-milers to the 2017 Moab 240 Endurance Run, where she beat the first man by 10 hours. Camille Herron has claimed the top overall spot in 24-hour and 100-mile events. And last October, Maggie Guterl became the first woman to be the last person standing in Big’s Backyard Ultra, a unique competition that involves completing the most laps possible of an approximately 4-mile loop. She endured for 60 hours and 250 miles.

It’s a transformation that has occurred largely in a single lifetime. When sport psychologist Joan Steidinger, Ph.D., was in high school in the 1970s, her parents wouldn’t allow her to run cross country because it was “unladylike.” But she picked up running later on, ran her first ultra—the 28.4-mile Quad Dipsea—in 1991, and then kept going, eventually finishing races like Western States.

“The mentality is so different now, and it gives room for women to push themselves harder, reach their full potential,” says Steidinger, the author of two books, Sisterhood in Sports: How Female Athletes Collaborate and Compete and Stand Up and Shout Out: Women’s Fight for Equal Pay, Equal Rights, and Equal Opportunities in Sports. “They’re winning races, and by hours and hours. It’s remarkable, and I think women’s potential is just beginning to be tapped.”

Bodies Built for Distance

World records at every distance from 100 meters to 100 miles belong to men by a margin of around 10 to 12 percent, and for largely biological reasons. For one, women have less muscle mass. Pump for pump, women’s smaller hearts shuttle less blood through their bodies. And with lower levels of the protein hemoglobin, each drop of that blood contains less oxygen, which working muscles require to produce energy.

Of course, world records match the best against the best. “You’d assume that there’s an equal number of people who have gone for it,” says Megan Roche, M.D., who studies athletes’ genetics and health—and is also a five-time national ultrarunning champion. “But at longer distance races, it’s so dependent on who shows up.”

And as more women take their place in the field, there’s added evidence that the longer the runway, the more ground they make up. At distances beyond 195 miles, women on the whole are .6 percent faster than men, the RunRepeat/IAU study found.

Ann Trason, ultrarunning pioneer, competes in the 1994 Western States. Photo: David Madison / Getty Images

As the miles pile on, the differences that hold women back in shorter events become less crucial. No one’s sprinting through 100 miles in the mountains, making cardiac output less crucial. In fact, there are some unique characteristics of female physiology that lend themselves to success at superlong efforts. “In some ways, we were made to go longer distances,” Guterl says.

Women, on the whole, tend to have more body fat than men, and higher levels of the hormone estrogen enable female bodies to turn that adipose tissue into energy, Roche says. In the later miles of a very long race, fat may be just about the only fuel left: The stores of energy called glycogen in muscles last only about 75 to 90 minutes, and while ultrarunners are notorious for eating everything from gels to soup to flat Coke and tacos to supply more glycogen, it’s impossible to replace every calorie.

Another advantage may lie buried in muscle fibers. Women’s muscles appear to contract less forcefully than men’s, which is another reason for their slower top speed. But research suggests that women’s muscles also possess greater ability to fire over and over with less fatigue. In one study done of men and women before and after the Ultra-Trail du Mont-Blanc in France, men showed more signs of burnout in their quads and calves at the end of the 110K distance.

Many have theorized that thanks to childbirth, women feel less pain—or at least, have the capacity to endure more of it. While science hasn’t yet settled this—one large research review suggested women actually feel pain more intensely—there’s no doubt many top female ultrarunners can withstand extreme duress. “Anecdotally, I have worked with some women who had a massive pain tolerance, and it’s pretty cool to see that play out over the longer distances,” Roche says. “It’s like, OK, I’ve been projectile vomiting for the last 13 hours, but I’m going to keep putting one foot in front of the other.”

Tougher terrain and unique race formats, such as Big’s Backyard, further level the playing field. Race director Lazarus Lake invites runners to his property in Bell Buckle, Tennessee. Each hour, they must complete a 4.16667-mile loop; hurt or exhausted runners drop one by one until only the winner remains. “I don’t think anyone really doubted a woman could win,” Guterl says.

Dauwalter came close, in 2018, losing to Johan Steene only after both had run 33 miles beyond the point any previous years’ competitors had reached. The next year, knowing that people—including Lake—were rooting for her as the first woman definitely gave Guterl an extra boost. “You have to be internally motivated,” she says. “But you definitely feel like you can’t let people down.”

Standing at the start line, I’ve always prepared as best as possible for everything I can predict will maybe happen, but then I’m acknowledging that there’s going to be some wrenches thrown in the day that I just couldn’t predict.

Now that women have more opportunities than ever to show what they’re made of, these fast foremothers are likely to pass endurance-enhancing traits down to their offspring. “Our cells make changes every time they turn over—it’s called epigenetics,” says Rhonna Krouse, MS, an associate professor of exercise science at the College of Western Idaho who’s run ultras herself and also studied other athletes. Through training adaptations, nutrition, and the environment in general, our very DNA is altered. “We’ve only been evolving as athletes for such a short period of time. It makes you think: Where can we go?”

The Endurance Mindset

Of course, as Guterl alludes, there’s another crucial element in ultrarunning: psychology. Though it’s less easily defined in studies and statistics, women at the top of the sport cite it as an indisputable advantage. “The longer you go, it breaks you down so much physically. The things that normally differentiate a man from a woman—more blood volume, more muscle mass, higher VO2 max—all those things don’t really matter as much,” Herron says. “Then it just becomes your mind trying to will your body through fatigue. I think there’s less of a differentiation between men and women mentally.”

Many of the psychological characteristics essential to superendurance align with typical female athlete traits, Roche says. That includes the focus, concentration, and discipline to toil daily in training and over long hours on the course, and the resilience to simply not quit when pain sets in—or when you’re struggling to stay awake, or hallucinating, says Dauwalter, who’s “seen” everything from pterodactyls to puppets playing on a swing set to a woman churning butter while racing.

Staying calm and problem-solving when an injury strikes or you go a few miles off-course also plays a key role. The top female ultrarunners see those occurrences not as obstacles, but opportunities to apply lessons from the past—or learn new ones. (This—in addition to the fact that trail surfaces have less injury-inducing impact—is one reason women can also appreciate and excel in ultrarunning as they age, Roche says; the more experiences you’ve had, the more resources you can draw on.)

“That’s part of the fun of these races and part of the puzzle,” Dauwalter says. “Standing at the start line, I’ve always prepared as best as possible for everything I can predict will maybe happen, but then I’m acknowledging that there’s going to be some wrenches thrown in the day that I just couldn’t predict. The make or break of just how successful the race goes is how you handle those wrenches that get thrown in and how you can keep your cool through fixing them.”

Approaching an event this way requires a healthy dose of humility, an ability to admit your mistakes and learn from them, Guterl points out—another common, if not uniquely, female trait. One way this may manifest is in pacing. Studies suggest women are better able to check their egos and start a race at a reasonable effort, which enables them to pick things up later in the race. As Guterl puts it, “you see a lot of dudes go out super-fast, but you pass most of them later.”

Courtney Dauwalter finishes through the pain at the Run Rabbit Run 100. Photo: Paul Nelson

But there’s a role for confidence too, which top female athletes undoubtedly possess. Most grew up without seeing themselves as limited or inferior. Dauwalter has two brothers, and says her parents didn’t place her in a separate category or suggest she couldn’t do certain activities because she was the only girl. Herron always played basketball with neighborhood boys, and never thought of them as being better or stronger. When she started running ultras, she noticed men surged forward while women held back; she naturally took her spot near the front and never let herself fade.

Curiosity, too, is what often leads women into the sport of ultrarunning in the first place, and it keeps them striving. After a few years of road marathons, Guterl became intrigued by an ultra in July in her then-hometown of Philadelphia. “I thought, ‘What’s it like to go this far? Can I do it?’” she says. And once she succeeded, she had new questions: “Can I do it better, or see how it is to go farther? I don’t really think I’m that fast, so the distance is where I think I excel.”

That hints at another key trait of successful ultrarunners: an ability to accept and embrace different types of goals. Often, the top aim in a grueling ultrarace isn’t to nab a specific place or time, but merely to finish, something Krouse had known from her own experiences as an athlete. And when she surveyed nearly 350 female ultrarunners for a study published in the Journal of Strength & Conditioning Research, she discovered she wasn’t alone.

While road racers at distances like the 5K and marathon are often motivated by pace targets or body composition goals, especially weight loss, ultramarathoners expressed far different attitudes. “Their top motivation was actually this sense of being,” she says, something less tangible that they achieved by facing their biggest doubts and fears and overcoming them.

It’s a shift on the normal balance between extrinsic motivation—for an outside reward, like recognition or a medal—and intrinsic motivation, a drive to participate in an activity for its own sake, and the personal rewards it provides. High-level athletes usually possess both, and in most sports in approximately equal amounts, Krouse says. But in female ultrarunners, the split seems to be somewhere around 75-25 in favor of individual transformation over external approval.

Somewhat ironically, it seems, the ability to let go of the goal of dominating may actually power women to the tops of podiums, simply by focusing on one small step at a time and staying open to opportunity when it arises. “I never go to a race thinking I want to win,” Pell says, though she admits it’s fun when it happens. “Even if there were no races, I would still do workouts and run like I am now because I love the process. I love the journey.”

Camille Herron won the Comrades Marathon in South Africa in 2017. Photo: Rajesh Jantilal

Stronger, Together

Of course, some women are motivated by victory, especially in competitive races like Western States. In 2019, Dauwalter explicitly aimed not only to defend her title—she won in 2018 in 17 hours and 27 minutes, the second-fastest women’s time ever—but also to break the course record. But even when their competitive switch is flipped, women are adept at balancing aggressive tendencies with collaborative ones. “Women, if you get them at their best, go in a circle with each other—they really can respect their competitors,” Steidinger says.

For Dauwalter, winning involves not an elbows-out battle against other racers, but a shared struggle to conquer the course; performing well elevates everyone. “Competing in a race with a ton of strong athletes helps you bring out your best. You can lift each other up by bringing the best version of yourself to a race, and then hopefully, it lifts the rest of the field up,” she says. “Everyone can see what their potential is, find their limit for how fast or how far they can go.”

That philosophy fits naturally with the trail and ultrarunning communities, which athletes describe as open, welcoming, and “chill.” Men and women alike tend to be accepting, inclusive, and collaborative, making it easier for new athletes, including women, to enter the space. It also aligns with the type of mentorship many women naturally provide, Krouse says. Those with big goals in the sport usually don’t insulate or isolate in relentless pursuit of them. Instead, they dedicate themselves to helping each other achieve.

For instance, Guterl is contemplating an attempt at an FKT—Fastest Known Time, a mark clocked on a given route that’s not an official race course—on Nolan’s 14, a run over 14 mountaintops in Colorado all above 14,000 feet. Meghan Hicks, the first female finisher, started a Facebook group for other women with the same idea in mind. There, they share tips on routes and techniques; Hicks was one of the first to congratulate Sarah Hansel when she claimed the FKT. “It’s just cool to see everyone encouraging everyone else to go for it, even if it’s your own record,” Guterl says. “They’re made to be broken, as they say.”

The same spirit of collaboration often applies even mid-race, Krouse says: “You feel like you’re all allies out there on the course.” Dauwalter has literally been lifted out of a mud puddle mid-race. Then there’s what happened at last year’s Western States, when a hip injury struck Dauwalter at about mile 80. Pain shot down her leg and her pace slowed to a walk.

Even as she felt her dream slipping away, she whooped, hollered, and doled out hugs when other women passed her, including eventual winner Clare Gallagher. And even though she wound up dropping out of the race, she wouldn’t have dreamed of being anywhere else but the finish line to watch Gallagher and others stream in, she says.

The Next Frontier

Scientists like Roche aren’t sure if women can ever completely outrun men at any distance. But Herron, for one, won’t let that stop her from trying. “The longer I go, the closer I come,” she says, noting that until Zach Bitter set a new men’s 100-mile record in August 2019, her 12 hours, 42 minutes, and 39 seconds was only 8 percent off the men’s mark. “I want to go 48 hours, six days, 1,000 miles. The question is, how far do I have to go that I could potentially maybe surpass the men’s world record?”

At times, it feels like eclipsing men is what’s required to attract equal attention to female athletes, Guterl laments. Male FKTs, for instance, are more often covered in running media than women’s. That relative lack of visibility could be one obstacle to drawing even more women into the sport. So, too, could a fear of being on trails alone, event entry policies that favor men, and limited racial diversity—women of color, failing to see many others who look like them, might shy away.

Grassroots groups like Trail Sisters and advocates like Mirna Valerio are trying their best to communicate that trail and ultrarunning really are for everybody—and raise the profiles of women in the sport for all to see. Races like Western States and the Hardrock 100, which have entry policies based on previous participation that skew male, could continue evaluating options to allow in more diverse fields, Guterl says. And as for the fear of being alone on a trail—more running groups may be the solution, though she points out that trails aren’t necessarily any more dangerous than city streets, and may even be safer.

While the COVID-19 pandemic may have temporarily made ultraraces inaccessible to everyone—Western States, Hardrock, Badwater, and more were all canceled for 2020—the rise in virtual racing may actually draw more athletes into the sport.

Lake called off his infamous 100-mile-ish Barkley Marathons in May and instead staged the The Great Virtual Race Across Tennessee 1,000K, in which more than 20,000 participants signed on to log 635 miles between May 1 and the end of August. “It’s inspiring for all of these people to come together to do this that wouldn’t have had access otherwise. Laz’s races are really hard to get into,” Roche says. “Innovative solutions are coming out of this, and it might transform running in the long term.”

And in the end, that might give even more women the opportunity to themselves be transformed, following in the footsteps of the ultrarunners who came before them. Dauwalter is as humble and effacing as a record-holder and champion could be, but says she’s glad if her victories inspire others to strive. “I love hearing people’s stories and that they’re trying a new distance or going after something that sounded too hard or impossible initially,” she says. “In general, we always set the bar too low for ourselves. If people can start to see this thing they thought was their limit isn’t, and they can push past that—I think that’s pretty cool.”