Are Women Closing the Gap?

This article was originally published in the April 2024 issue of UltraRunning Magazine. Subscribe today for similar features on ultra training, racing and more.

Before the female ultrarunning superstars of today had muddied their sneakers on the world’s toughest trails, Ann Trason was setting those trails ablaze.

With her name inscribed on multiple world records and having cemented her place in the American Ultrarunning Hall of Fame, Trason is perhaps the most decorated female ultrarunner of all time. Choosing among her catalog of victories for a favorite is a tall task, but the 1989 Sri Chinmoy USA National 24-Hour Championship is surely up there—not just for the records she broke that day but for the glass ceiling she shattered in the process.

The race began at 8 a.m. on a Saturday in September, just as the sun inched above the horizon, leaving a glassy chill in the air. After a moment of silent meditation, led by Sri Chinmoy himself, a foghorn signaled the start of the race and 47 runners surged across the line. With running legend Ted Corbitt directing a chorus of cheers from the crowd, three runners led the field: Don Fries, Ray Krolewicz and, of course, Ann Trason.

Fast-forward to the halfway mark, as cloudy skies relented to rain, Trason had run 88 miles and set a new women’s world record. Less than 2 hours later, she’d crested the 100-mile mark to crush another women’s record. The 200k record fell shortly after.

The final third of the race saw cracks appear in Trason’s seemingly impenetrable armor. As is common with prolonged and intense running, the body systems begin competing for limited resources. The leg muscles, in their hunger for oxygen and fuel, steal blood from the rest of the body, and the digestive system is usually the first to suffer the consequences. Trason developed worsening abdominal pain. It eventually gave way to dry heaves when her food backed up in her gut like a freeway traffic jam. Nauseated and unable to drink, she became progressively dehydrated.

It was a crucial point in the race. Scott DeMaree and Tom Possert were chasing her shadow and another legendary runner, Sue Ellen Trapp, was moving rapidly through the field. Trason was tested to her limits. But even after torrential rain had turned the trail into pancake batter, Trason remained stoic, continuing her relentless charge into the history books. By the time the race clock had completed its second revolution and the horn sounded the race’s end, the unthinkable had happened: Ann Trason had won the Sri Chinmoy USA 24-Hour National Championship outright, running 143 miles and 139 meters, besting one of the strongest fields of male runners in 24-hour race history. It was a landmark day for ultrarunning, laying a foundation on which women of the sport would be building for decades.

A New Frontier

Trason retired in 2004 at the top of her game. Since then, numerous female athletes have gone the extra mile in a male-dominated sport. Among them is Courtney Dauwalter, who won the Moab 240 in 2017, finishing 9 hours ahead of the first man in second place. In 2023, Camille Herron set a new 48-hour world record by running 435.34k (270.5 miles), beating the previous record (also held by a woman) by 15.5 miles. Also in 2023, Ashley Paulson won the Badwater 135 in Death Valley outright in a time of 21:44:35, beating Simen Holvik by nearly 44 minutes. What was “unthinkable” in Trason’s time, has become almost commonplace.

These remarkable feats of endurance complement the overall trend that women are closing the gap to men in longer running races. Although men are about 10% faster than women in the marathon [1], the gap has been reported as 9% over 50 miles [2], 5% over 24 hours [3] and 4% over 100 miles [2]. One analysis of nearly 40,000 trail races from 1989 to 2021 found that “The gap between men and women shrinks when trail running distance increases…” [4].

This led to endless speculation in the media that women may be “built” for ultramarathon. In recent years, we’ve been treated to headlines including “Why Women Rule,” “Why Women Are Better at Ultrarunning,” and “If Male Athletes Can Run Fast, Female Athletes Can Run Far,” [5–13]. In 2021, I wrote a lengthy review with experts in the field to offer some clarity on the issue and lay to rest some of the guesswork [14]. But with each new female success, athletes and coaches continued to fan the flames of speculation.

But it’s speculation that’s fundamentally flawed. Nearly every ultramarathon ever contested has had lopsided participation numbers, with women comprising just 10-30% of any given field [2,14]. This discrepancy is more than enough to misrepresent the true performance potential for women in the sport. It could be helping or hindering the narrative. On the one hand, a shallow pool of female runners won’t reflect the diverse capabilities of females more broadly, leading to an underestimation of their abilities. On the other hand, women who enter extreme footraces knowing they’ll be outnumbered by men five to one might be self-selecting as the toughest and most determined of the sex, potentially overestimating their performance potential. And so, speculation about the female advantage in ultrarunning is at best, overreaching and at worst, flagrantly sensationalist.

For years now, I’ve been fascinated with the notion of ultramarathon as a “great equalizer,” being perhaps the only sport where men and women, young and old, can compete on relatively equal footing. Each time I’ve tried offering clarity on the question of, “Are women built for ultrarunning?” [14,15] I’ve concluded that it’s an impossible question to answer until we can make meaningful comparisons. For that, we need data from races where the sexes compete in equal numbers. For many years, it appeared that such races would never occur.

A Spark of Inspiration

At the end of last year, I was sitting in a coffee shop working on my regular column for UltraRunning Magazine,* when my cellphone lit up like a Christmas tree. Someone had sent me a link to a feature in the magazine titled, “Baker Ultra: Making Room for the Women.” The piece, written by Amy Nelson, described several initiatives that she and the other race organizers had implemented to attain parity in gender participation. They’d not only arranged free group training that provided safety in numbers and confidence-building for females running on the trails, but also—in a move that’s obvious in its simplicity but that rarely manifests elsewhere—the team allocated equal spaces to men and women. The outcome was a starting field at the Baker Ultra that, for the first time in the race’s 20-year history, comprised an equal number of men and women. It was a significant milestone for the sport.

The cogs in my brain started to turn as I wondered what other races, if any, had achieved gender parity. I scoured the internet, but instead of finding efforts to expand female participation, found just a series of empty pledges and a vague hope within the community that parity would happen by itself, like a meme taking hold and going viral without explanation. I was about to give up when I discussed the issue with coach and UltraRunning columnist Jason Koop. He told me about the High Lonesome 100—a race in his home state of Colorado—which had also achieved an equal gender split. In fact, the Baker Ultra 50 and the High Lonesome 100 both had starting fields that were 52% female.

It was the spark of inspiration I needed to set up a formal analysis. I now had two databases, from 50 and 100-mile races, that would finally allow me to set the record straight and answer two lingering questions: (i) what happens to the performance gap in ultramarathons when there are equal numbers of men and women? And (ii) are men or women more likely to place higher over 50 and 100 miles?

Boxout 1: Race profiles and runner demographics

The Baker Trail UltraChallenge is a 50-mile, point-to-point course, predominantly on compact and rocky trail, with 6,320 feet (1,926 m) of cumulative ascent. The male record of 7:29:56 was set in 2020, and the female record of 8:19:46 was set in 2012. Overall, 116 runners started the race, of which 52% were female.

The High Lonesome 100 is a 100-mile, single-loop course, predominantly on a mountainous trail, with 23,500 feet (7,163 m) of cumulative ascent. It is mostly contested at high altitude. The male record of 20:58:57 and the female record of 23:40:29 were both set in 2022. Overall, 143 runners started the race, of which 52% were female.

Course profiles for the 50-mile race (top panel) and the 100-mile race (bottom panel).

Unique Data for a Unique Sport

The obvious comparison was male and female finish times in each distance. I wanted to assess this not only in terms of the overall performance (i.e., comparing finish times between all men and women who finished), but also the top-tier performances (i.e., comparing finish times between the top 10 males and top 10 females). After organizing runners into the relevant groups, I calculated the averages and performed some basic statistical tests to determine if any differences were meaningful (see the boxout for an explanation of why statistical analyses are important).

Both races were hotly contested, and you can see the results in the figures and tables. The Baker Trail 50 was ultimately won by Jason Tanner (M) in 8 hours 20 minutes and 55 seconds, with second place Anna Balouris (F) crossing the finish line around 8.5 minutes later. The average time for the 96 finishers was 12 hours and 38 minutes, with just 1.2% separating men and women (around 9 minutes).

There was a similar pattern in the High Lonesome 100. First place Ryan Smith (M) finished the grueling course in 20 hours 58 minutes and 57 seconds, with second place Annie Hughes (F) around 2 hours and 40 minutes behind. The average time for 91 finishers was 31 hours and 35 minutes with 3.2% separating males and females (around 60 minutes). For context, a performance gap of 1.2-3.2% would equate to 3-7 minutes over a typical non-elite marathon. These may seem like notable differences at an individual level, but at the level of the broader population, when variability in finish times and age were factored into the analysis, the differences were not statistically meaningful. So, parity in participation numbers essentially shrinks the overall sex difference in performance to a few percentage points in 50 and 100-miles races.

There was a markedly different story when comparing top performers over 50 miles. Men were much more likely to finish in the top 20% of the field (15 males versus four females), and the top 10 males were approximately 14% (85 minutes) faster than the top 10 females. I’m not the first person to notice this phenomenon. Something similar has been reported in 50-mile races in Germany [16] and North America [17], albeit in fields with unequal participation numbers. Our results confirm that the fastest males seem to retain a substantial advantage over 50 miles. By contrast, there was no statistical difference between the top 10 males and the top 10 females over 100 miles.

Finish times for males and females in the 50-mile race (top panels) and the 100-mile race (bottom panels). In 50 miles, the difference in overall finish time was 1.2%, with a difference of 13.8% for the top 10 finishers in each group. Over 100 miles, the difference in overall finish time was 3.2%, with a difference of 4.4% (p > 0.05) for the top 10 finishers in each group.

Delving into the Science

The results are intuitive based on what we know about the human body. Shorter races like marathons, half marathons and Olympic-distance triathlons are run at faster velocities (or higher exercise intensities) than the typical ultramarathon, placing greater demands on the body’s ability to use oxygen [18–20]. Think of maximal oxygen uptake as analogous to a car engine: vehicles with larger engines can burn more fuel and generate more power, e.g., a powerful Mustang versus a Prius. Men, with their larger bodies, hearts and lungs, have larger oxidative capacities and usually have the advantage in shorter distances. So, men usually outperform women in the marathon, and the fastest runners in 50-mile events also tend to be men.

But ultramarathons are not just “long marathons,” nor do they depend on the same physiology. The relative contribution of maximal oxygen uptake to running performance diminishes with increasing distance and decreasing speed [21]. In fact, performance over 100 miles depends on many additional factors, like fatigue resistance and fuel economy, both of which are greater in females [22,23]. Women also tend to weigh less than men, perhaps paying dividends in very long races, especially when running uphill [24,25]. Long ultramarathons could provide the very conditions that permit greater uniformity in finish times between the sexes. After all, a Prius is a lot less powerful than a Mustang, but I know which one I’d prefer to drive cross-country.

One thing that’s obvious in this emerging area of research is that, unlike in most other sports, raw power and strength offer sanctuary to no one. The physical attributes most closely aligned to performance in long-distance ultra trail running—fatigue resistance, fuel economy, mental toughness—are accessible to anyone, man or woman, young or old. This makes ultramarathons the great equalizer.

Cooling the Jets: Considerations and Caveats

As with all studies, our results must be contextualized. Something we didn’t anticipate was that females would have higher dropout rates than males. In fact, while the starting field was 52% female, finishers were 46% and 45% female (in 50-mile and 100-mile races, respectively). Although this slightly weakens the sex-based comparison, the study remains the most robust analysis of male and female ultramarathon performances to date.

There’s no obvious physiological explanation for the higher dropout rates in females. In fact, in a small experiment we published a few years ago, we found that female finishers of UTMB had fewer physiological disturbances than their male counterparts, even when comparing runners of similar finish times [15]. So, we think the higher dropout rates at Baker and High Lonesome may have a psychosocial explanation. Parity at the Baker Trail depended on recruitment strategies that targeted females. Race organizers offered free group training that provided safety in numbers and helped females build confidence on the trails. It’s quite likely this inspired the participation of some women who’d never have normally entered an ultramarathon. In other words, these novel recruitment strategies got disproportionately more females to the start line than the finish line.

Another consideration is that we examined just two races from several thousand contested each year around the world, each run on slightly different terrain and in unique environmental conditions. One oft-cited analysis from RunRepeat (not peer-reviewed) estimated there are more than 600,000 ultramarathon participants each year, and our study represents a tiny fraction of that.

Boxout 2: Why do we need statistical analyses?

Looking at average finish times is a good starting point, but it doesn’t offer a nuanced interpretation of the data. For instance, averages don’t give any insight into the group’s viability. Let’s say one male runner had an abnormally fast finish time because he found a bike at 30 miles, pedaled furiously for 10 miles and ditched the bike before finishing the race on foot. Or a female runner had an abnormally slow finish time because she tripped on a tree root at 45 miles, rolled her ankle and limped to the finish. Those individual times would be included in the overall results, skew the averages and lead us to incorrectly conclude that “men are faster ultra runners.” Statistics enable us to account for such anomalies.

What if the men were considerably older than the women? One would expect younger athletes to have a competitive advantage and run a fast race. Comparing only the means doesn’t account for “confounding factors” like age.

And how do the differences we observe in male and female finish times relate to the population at large? We saw a difference of 1.2% over 50 miles, which equated to around 9 minutes. That’s enough to make up several places at an individual level, but it’s probably meaningless when framed among all factors that potentially influence performance (I once had a severe stomachache at the 30-mile mark of Marathon Des Sable on day 4. I stopped at a checkpoint, sat down to tie my shoe and couldn’t get up for 90 minutes. Many factors can cause similar delays.)

A statistical analysis provides a nuanced interpretation of the results by helping us account for variability, confounding factors and values we’d expect to see in the broader population.

Scientific research in ultramarathon has increased exponentially since 2010, with more studies published in the last decade than in the preceding five. Although there’s a great deal we don’t yet know about this complex and multi-dimensional sport, each new study is another puzzle piece that slots into place and helps us see the overall picture.

We are, nevertheless, lacking data on the female responses to ultramarathon. This is due partly to the underrepresentation of women in exercise-related research, and partly due to the low participation of women in ultramarathon. It remains a profound problem, not only thwarting coaches in their efforts to design female-specific training programs, but also preventing race directors and medical personnel from providing optimal care to contestants (e.g., we know the approximate likelihood of a man suffering acute kidney injury after a long race, but we don’t have similar data in women).

There’s no obvious physical reason why women and men cannot race ultramarathons in equal numbers, just as they do in nearly every other sport. Just as Anne Trason inspired the next generation of women to push the boundaries of human ultramarathon performance, we hope the examples set by the Baker Ultra and the High Lonesome will steer the direction of the sport toward greater female participation. The data we’ve presented suggests it could lead to great things.

* The column is called Ask the Physiologist. Each month, I compile 2–4 questions, sent to me by readers of the magazine, that relate to the science of ultramarathon. I do my best to provide concise, evidence-based responses. Submit your question to [email protected].

References

1. Deaner RO, Carter RE, Joyner MJ, Hunter SK. Men are more likely than women to slow in the marathon. Med Sci Sports Exerc. 2015;47:607–16.
2. Waldvogel KJ, Nikolaidis PT, Di Gangi S, Rosemann T, Knechtle B. Women Reduce the Performance Difference to Men with Increasing Age in Ultra-Marathon Running. Int J Environ Res Public Health. 2019;16:2377.
3. Peter L, Rüst CA, Knechtle B, Rosemann T, Lepers R. Sex differences in 24-hour ultra-marathon performance – A retrospective data analysis from 1977 to 2012. Clinics (Sao Paulo). 2014;69:38–46.
4. Le Mat F, Géry M, Besson T, Ferdynus C, Bouscaren N, Millet GY. Running Endurance in Women Compared to Men: Retrospective Analysis of Matched Real-World Big Data. Sports Med. 2023;53:917–26.
5. Palmer J. Leah Goldstein: the cyclist who raced men across America … and won. The Guardian [Internet]. 2023 Jun 13 [cited 2023 Dec 25]; Available from: https://www.theguardian.com/sport/2023/jun/13/leah-goldstein-the-cyclist-who-raced-men-across-america-and-won
6. If Male Athletes Can Run Fast, Female Athletes Can Run Far [Internet]. Office for Science and Society. [cited 2023 Dec 25]. Available from: https://www.mcgill.ca/oss/article/student-contributors-health-and-nutrition/if-male-athletes-can-run-fast-female-athletes-can-run-far
7. Are women better ultra-endurance athletes than men? BBC News [Internet]. 2019 Aug 9 [cited 2023 Dec 25]; Available from: https://www.bbc.com/news/world-49284389
8. Magazine WR. Why women are better at ultra running [Internet]. Women’s Running. 2016 [cited 2023 Dec 25]. Available from: https://www.womensrunning.co.uk/inspiration/why-women-are-better-at-ultrarunning/
9. Brueck H. Women are faster long-distance runners than men, and it’s probably because they’ve got more estrogen [Internet]. Insider. [cited 2023 Dec 25]. Available from: https://www.insider.com/women-are-faster-long-distance-runners-estrogen-2020-1
10. Why Women Rule [Internet]. Runner’s World. 2010 [cited 2023 Dec 25]. Available from: https://www.runnersworld.com/trail-running/a20803612/why-women-rule-ultrarunning/
11. Bloom B. Could women run faster than men? The Telegraph [Internet]. 2020 Jul 29 [cited 2023 Dec 25]; Available from: https://www.telegraph.co.uk/athletics/2020/07/29/could-women-run-faster-men-science-says-might-possible/
12. More women gain ground in ultramarathons, other long-distance races. Washington Post [Internet]. 2020 Sep 26 [cited 2023 Dec 25]; Available from: https://www.washingtonpost.com/health/women-long-distance-runners/2020/09/25/bffdda10-1871-11ea-a659-7d69641c6ff7_story.html
13. Are women ‘made’ for ultrarunning? Camille Herron seems to think so [Internet]. Runner’s World. 2023 [cited 2023 Dec 25]. Available from: https://www.runnersworld.com/uk/news/a44172975/are-women-better-endurance-runners/
14. Tiller NB, Elliott-Sale KJ, Knechtle B, Wilson PB, Roberts JD, Millet GY. Do Sex Differences in Physiology Confer a Female Advantage in Ultra-Endurance Sport? Sports Med. 2021;51:895–915.
15. Tiller NB, Wheatley-Guy CM, Fermoyle CC, Robach P, Ziegler B, Gavet A, et al. Sex-Specific Physiological Responses to Ultramarathon. Med Sci Sports Exerc. 2022;54:1647–56.
16. Zingg MA, Knechtle B, Rosemann T, Rüst CA. Performance differences between sexes in 50-mile to 3,100-mile ultramarathons. Open Access J Sports Med. 2015;6:7–21.
17. Coast JR, Blevins JS, Wilson BA. Do gender differences in running performance disappear with distance? Can J Appl Physiol. 2004;29:139–45.
18. Gómez-Molina J, Ogueta-Alday A, Camara J, Stickley C, Rodríguez-Marroyo JA, García-López J. Predictive Variables of Half-Marathon Performance for Male Runners. J Sports Sci Med. 2017;16:187–94.
19. Billat VL, Demarle A, Slawinski J, Paiva M, Koralsztein JP. Physical and training characteristics of top-class marathon runners. Med Sci Sports Exerc. 2001;33:2089–97.
20. Coates AM, Berard JA, King TJ, Burr JF. Physiological Determinants of Ultramarathon Trail-Running Performance. Int J Sports Physiol Perform. 2021;16:1454–61.
21. Davies CT, Thompson MW. Aerobic performance of female marathon and male ultramarathon athletes. Eur J Appl Physiol Occup Physiol. 1979;41:233–45.
22. Besson T, Parent A, Brownstein CG, Espeit L, Lapole T, Martin V, et al. Sex Differences in Neuromuscular Fatigue and Changes in Cost of Running after Mountain Trail Races of Various Distances. Med Sci Sports Exerc. 2021;53:2374–87.
23. Blaak E. Gender differences in fat metabolism. Curr Opin Clin Nutr Metab Care. 2001;4:499–502.
24. Lember L-M, Di Virgilio TG, Brown EM, Rodriguez-Sanchez N. Hill Runner’s Physiology, Performance and Nutrition: A Descriptive Study. Front Sports Act Living. 2021;3:676212.
25. Berzosa C, Gutierrez H, Bascuas PJ, Arbones I, Bataller-Cervero AV. Muscle Tone and Body Weight Predict Uphill Race Time in Amateur Trail Runners. Int J Environ Res Public Health. 2021;18:2040.

The terms “male and female” in this article were used interchangeably with “man and woman” to aid readability and flow and to streamline the discourse. This usage was not intended to overlook the nuanced definitions of the terms or the distinctions between sex and gender.