Are women better than men at endurance running?

“The race is too hard for women. They are simply not tough enough to do it.”

Those are the words of Lazarus Lake, race director of the Barkley Marathons – one of the world’s hardest ultramarathons which to date, of the approximate 1,000 people who have started, only 20 have ever completed.

Speaking in 2015 and daring for someone to prove him wrong, it took nine years until a British ultra-runner did just that.

Completing the extreme 100-mile course with just one minute 39 seconds to spare of the 60-hour cut-off, Jasmin Paris from Midlothian made history and cemented her name in the ultra-running history books.

But now, increasingly, she is not alone.

Last summer, there was a female one-two for the first time in the gruelling Montane Summer Spine Race from Derbyshire to Scotland. Rachel Entrekin set a new course record and became the first woman to win the Cocodona 250 in Arizona in May, while last month Sophie Woods smashed the overall record by six days to complete the Via Alpina.

It appears female runners are no longer just taking part in ultra-endurance events, they are competing with their male counterparts, breaking records and in some cases, winning races outright.

All of this has prompted suggestions that they are perhaps better suited to these kinds of challenges.

But is there any scientific proof? Do women really have any physiological or psychological advantages in endurance exercise (anything that takes more than six hours)? And if so, could we see more of these records fall in the future?

Are women better suited to endurance exercise than men?

In running distances up to the marathon, there is on average a 10-12% performance gap between males and females.

Men are generally stronger and built with a bigger aerobic engine.

But as the distance increases, those physical advantages appear to become less relevant and the gap starts to narrow.

The “gender pace gap” diminishes to 0.25% in 100-mile races, according to a study of more than 20 years of amateur ultra-race data conducted by RunRepeat, in collaboration with the International Association of Ultrarunners,

Anything further than 195 miles and women have the potential to be faster.

For Professor Andy Jones, an expert in endurance performance at the University of Exeter, there are three potential physiological explanations why women could perform better over longer distances or durations.

Fat metabolism – women have higher fat stores and burn it more efficiently, giving them a steady energy source for longer.

Muscles – women have more oxygen-efficient muscle fibres, known as “slow twitch”, that are better suited for endurance activities.

Fatigue resistance – women retain more strength over hours of endurance exercise.

However, Jones, who played a key role in Eliud Kipchoge’s sub two-hour marathon challenge in 2019, is keen to point out that the science in this area is “behind”.

“There isn’t as much hard evidence as there would be for shorter distances, which have been studied for a long time in quite some detail,” he adds.

That is a view shared by Dr Richard Burden, co-lead of female athlete health and performance at the UK Sports Institute, who feels a lot more information needs to be gathered before conclusions can be made.

“At the moment we are speculating … there are definitely some physiological adaptations that you see more in women than men that are favourable for ultra-type events. But those need to be better established and more studies would need to be done.”

Physiology, however, only gets you so far. The realities of ultra-endurance exercise – multi-day events, sleep deprivation, extreme terrain and conditions, to name but a few – mean the journey to the finish line is as much mental as it is physical.

And for Sophie Woods, this is where women have the edge.

“It’s not necessarily about being the fastest person at the start,” she says. “It is about preparation, it is about mental strength and being able to continue to persevere when things go wrong.”

During the New Zealand runner’s record-breaking run of the Via Alpina, she was forced to expect the unexpected – from disruption caused by wildfires that made her route longer and more dangerous to swarms of horseflies.

“I was so tired and there were so many of them and I wanted to have a complete meltdown and just cry, but I couldn’t because if I stopped moving, they started biting me,” she says.

“I think women are really good at adapting and continuing and just knowing that once we start something, you’ve just got to keep moving until you get to the finish.”

That view is echoed by Yngvild Kaspersen, who last month became the first woman to win the prestigious Ultra-Trail Mont Blanc CCC race in the Alps twice. She credits her victory to the “mental game” she puts herself through in training.

The Norwegian, who balances life as a professional runner with her job as a GP, also believes female ultra-runners are so strong because camaraderie in the community is unrivalled.

“We’re competitors but we’re also motivating each other, inspiring each other, pushing each other to do better in the races,” she says. “If you see the podiums for the women this year [at UTMB], how close we are and how we’re running together out there – that’s very special and I’m very proud to be a part of that community and that group of women.”

So can we explain why women might be more resilient?

Sports dietitian Renee McGregor, who specialises in athlete nutrition and hormonal health, believes the answer comes from the female body itself.

“The moment women step into puberty, we are dealing with a fluctuating hormonal system,” she says. “We never ever give ourselves credit for that, it’s just an accepted part of being female. But actually, it is an endurance in itself and I think that’s probably where a big part of our resilience comes from.”

McGregor, an ultra-runner herself, points to research that suggests female runners display more disciplined and even pacing strategies than men in distance races, maximising on what she terms the female “brain bank”.

“I don’t think women go into these races without a lot of thought and contingency planning,” McGregor adds.

“For example, if you’ve been through a pregnancy and you’ve dealt with nausea, if you’ve had a baby and dealt with the lack of sleep or if you’ve gone through fertility treatment, you have to go through so much discomfort, but you know you can get through it. And I think it’s that knowledge of ‘I can get through this, I can find a solution’.”

Image source, Zoe Salt

Sophie Woods pushed through the final days of the Via Alpina on one-and-a-half to two-and-a-half hours of sleep

One of the biggest reasons why we cannot talk with any certainty about the potential physiological and psychological advantages that women may have in this field is because participation numbers are low, with women making up roughly only 20% of those on ultramarathon start lines.

Research by SheRACES, a network set up by British ultra-runner Sophie Power to correct gender disparities in running, suggests the reasons for this range from societal perceptions around women’s abilities, to concerns around the time needed for training, or access to the right support at the events themselves.

Slowly but surely, however, things are starting to change.

Earlier this year, a trail race in New Zealand became the first UTMB World Series event to achieve a 50:50 gender split, while a leading UK race provider has launched a new initiative to target gender parity at its events.

And now, according to Dr Burden, society is talking about the limits of human performance in a different way too.

“Historically, the majority of the time it [the limits of the human] will be established from male models or male sports,” he says. “Now we’re starting to break it up into the limits of male performance and the limits of female performance and that’s a distinction that needs to be made … but to make better comparisons, we would need more women taking part in ultra events.”

When it comes to participation, visibility is key.

Kaspersen describes Rachel Entrekin’s historic victory at Cocodona 250, one of the most demanding ultramarathons in the world, as an “inspiration” among the elites to “dare to try”.

And at the amateur level, there are those like Emily Fairs, a 22-year-old ultra-runner who documents the realities of her training and races on social media as part of her mission to get more women of all ages on start lines.

“When it comes to endurance training, there are so many components that come into it and that we are fearful of but by seeing another woman do it you think ‘right, if she can do it, if she has the tools, she has the knowledge, she has the ability to do all these crazy difficult challenges, then so do I. I’m no different to her. She’s no different to me’,” says Fairs.

Fairs says she has received thousands of messages from women about how her content has encouraged them to lace up their trainers, and believes recent trends of female success in ultra-running are just the start.

“When the proportion is so low, we have no clue what women are capable of. We’re starting to see more women get faster and enter the sport and push themselves and break records. So, who knows where we’ll be 10-15 years later down the line?”

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