Fuelled by beer and tacos, endurance athlete Camille Herron stormed to victory at the USA Track and Field 100-mile Championships in Nevada last month.Her triumph was significant for several reasons. Firstly, Herron broke her own women’s world record, crossing the line in 12 hours, 41 minutes and 11 seconds.Secondly, the American smashed the 50-mile world record in the 40 to 44-year-old age category with a time of 6:08:24.Lastly, but by no means least, Herron finished nearly 30 minutes in front of the fastest male athlete, Arlen Glick. He placed second in 13:10:25.This may seem surprising – after all, there are very few examples in mainstream sports where a female athlete has overcome a male opponent. But, in the world of ultra-endurance sport, women beat men on a relatively regular basis.Back in January 2019, British ultra-runner Jasmin Paris became the first woman to win the 268-mile Montane Spine Race in the UK.She finished the course in 83:12:23, obliterating the course record by 12 hours. She was still breastfeeding her daughter at the time, and even stopped off mid-race to express milk.Paris’s nearest opponent, a male athlete, finished 15 hours behind her.Five months later, British junior doctor Katie Wright won the Riverhead Backyard ReLaps Ultra-marathon in New Zealand. She ran almost nonstop for 30 hours, beating 40 men and six other women.

The examples keep on coming. Courtney Dauwalter has won numerous ultra-marathons, including the Moab 240, a 238-mile race in the oppressive heat of the Utah desert. The first man finished 10 hours later.

It’s not just running. In swimming, the four longest distances achieved in open water, without the assistance of currents, are held by women.

Sarah Thomas has swam the farthest, setting a record of 104.6 miles in 2017. According to the Marathon Swimmers Federation, this is almost 39 miles more than the men’s record.

Last October, Chloë McCardel managed a record-breaking 44th English Channel swim. Among these attempts included the longest non-stop ocean swim – 77 miles in 42 hours.

Women have beaten men in cycling ultra-endurance events, too. In 2016, Lael Wilcox triumphed at the Trans Am Bike Race, a 4,400-mile trek across the US.

So, why is this possible? Why can women outperform men over extreme distances?

In 2019, Dr Nicholas Tiller, a senior lecturer in applied physiology at Sheffield Hallam University, told the BBC that it was down to a greater distribution of slow twitch muscle fibres in women.

These muscle fibres are more resistant to fatigue and more suited to endurance. Men may have bigger muscles and greater maximal capacities like strength and aerobic power, but these are deemed to be less important in an ultra-endurance event.

"One of the reasons why women tend to be able to compete with men and sometimes outperform them, is that the greater maximal capacities exhibited by men aren't as important in an ultra-endurance event," Dr Tiller said.

"Ultra-marathons are the great equaliser, because there are no other sports where men and women can compete side by side in terms of physicality."

Women may also benefit from a more efficient storage of glycogen, a point made by exercise scientist David Rowlands from Massey University in a conversation with Insider.

There may be psychological factors behind the phenomenon too. Dr Carla Meijen, a senior lecturer in applied sport psychology at St Mary's University, was another to speak to the BBC in 2019.

"When we think about ultra-endurance events, one of the things that's quite prevalent is emotions because you get fatigue, sleep deprivation and tiredness and that causes things like confusion and less helpful emotional responses,” she said.

"Typically females use more emotion-focused coping so they focus more on how to reframe what they are feeling than males in general. That might be a reason why they may be more suited to those more ultra-endurance events."

It has also been found that painful experiences such as childbirth may have helped female ultra-endurance athletes.

"Some female participants said events such as childbirth had helped them to deal with the pain and meant they had more belief in themselves so that they could push through the pain," Dr Meijen said.

"When you think about ultra-endurance, it is a very painful experience."

Unfortunately, there has not been enough research carried out to know for certain why women can beat men in ultra-endurance events, partly due to the very small sample sizes available.

“Ultra-endurance events are niche and the small numbers of women participating make extrapolation challenging, and it’s rare to find direct comparisons with men,” wrote Dr Nish Manek in Science Focus.

Indeed, it may just be the case that an elite female runner has trained incredibly hard for an event, and is competing in a field where the standard of male athletes is much lower.

As a wider point, there has been nowhere enough research conducted into the performance of female athletes in elite sports in general. Until this changes, it’s unlikely that an answer to the ultra-endurance event phenomenon will be found.

Even without answers, the achievements of Herron, Paris, Wright, Dauwalter, Thomas and others can still be viewed with absolute awe and admiration. Their performances are an inspiration to women around the world.