We visited Exeter University to meet the physiologists who are helping Faith Kipyegon and Nike’s Breaking Four project but under no illusions as to how hard the feat will be

If supermiler Faith Kipyegon manages to give the four-minute barrier a fright in Paris this month, a small team of sports scientists at the University of Exeter will no doubt smile in satisfaction, knowing they played a small part in the achievement.

In recent months they have worked with the Olympic 1500m champion and Nike on the bold bid to create the world’s first sub-four-minute mile by a woman. This has involved them doing physiological testing on the 31-year-old, in addition to wider research on the demands required for such a feat.

To find out more, I visited the St Luke’s Campus in Exeter last month, where I met Professor Andy Jones from the team, plus PhD student and Northern Ireland 1500m champion Rebekah Osborne.

This leafy area of the city is full of bright-eyed, sporty-looking students, but it was once the site of a gallows in the city. In 1682, for example, three women were hanged there for witchcraft.

Yet how times have changed. There was no black magic at play when the first sub-five-minute mile by a woman took place in 1954, with Diane Leather breaking the barrier in Birmingham less than a month after Roger Bannister ran the world’s first sub-four-minute mile. ITwo years ago, Kipyegon set the current world record of 4:07.64 and it now seems heresy to suggest the four-minute barrier will not be breached one day.

“It’s not impossible,” says Jones, “but it’s going to be very hard!”

Jones is a world-leading physiologist and was also an excellent runner in his youth. In 1987 he set UK age 17 records for 10km with 30:13 and half-marathon with 66:55, he represented Britain at the Youth Olympics and  clocked a nifty 4:05 for the classic distance of one mile. In the latter he remembers being passed by Steve Jones, the former world marathon record-holder, in the closing stages.

More recently he came within a minute of breaking the three-hour barrier for the marathon, aged 49 in Moscow, although now, at 55, injuries have taken their toll and “the opportunity has gone”.

Outside of the world of academia, he is best known for being a long-time member of the team that helped Paula Radcliffe scale the heights of a 2:15:25 world marathon record, while he also helped popularise the use of beetroot juice as a performance enhancing food and supplement. Previous Nike-related work, meanwhile, has centred on the “Breaking2” event in Monza, Italy, in 2017 where Eliud Kipchoge clocked 2:00:25 before two years later smashing the barrier with 1:59:41 at the INEOS 1:59 Challenge in Vienna.

“Not a huge amount changed from Monza to Vienna,” Jones says. “I think Eliud just needed ‘another chance’ and in Vienna he had more confidence and knew he could do it. The pacers were maybe holding him back that day, too, and he might have potentially run 1:58.”

Jones and Osborne readily admit that Kipyegon’s chances of breaking the four-minute barrier for the mile this month are slimmer than Kipchoge’s sub-two-hour marathon in 2019.

In the team’s academic paper, "Seven (.65) Seconds Away: The Possibility and Physiology of a Women’s Sub-4 Minute Mile”, which has been published in the Journal of Applied Physiology, they write: “To our knowledge, there is no female athlete presently displaying the endurance parameter ratio, or other physiological characteristics, required to run a sub four-minute mile.

“Moreover, 800m performance amongst the world’s best women presently appears insufficient to suggest that a sub four-minute mile is imminent. However, there are many factors which could be optimised to help bridge the ~8-s gap from the current world record of 4:07 to 3:59.”

Despite this, the team is optimistic that Kipyegon can at least creep further toward the four-minute barrier that was once considered “impossible” for men. The Kenyan is “the closest to displaying the physiological capabilities we outline in our paper.”

Jones adds: “In comparison to men, the history of elite running is relatively brief among women, and there is also much less research on the physiology of elite female athletes. Women have repeatedly defied social dogma and taken sport to a level once assumed to be impossible.

“Our research paper outlines how we can optimise physiological preparation for middle-distance running through training, nutrition and other factors. We conclude that a woman could break the four-minute mile within the next decade.”

Certainly the women’s mile record has fallen dramatically – by 52 seconds, in fact, in the last 70 years. The longest race at the Olympics for women in the 1960s, for example, was only 800m, with the 1500m – or metric mile – not introduced into the Games until 1972.

Following Leather’s 4:59.6 in 1954, the 4:30 barrier for the mile record fell 19 years later when Paolo Pigni clocked 4:29.5. The 1980s saw the record go from 4:21.7 (Mary Decker) to 4:15.61 (Paula Ivan), whereas Svetlana Masterkova’s 4:12.56 in 1996 survived for 23 years before Sifan Hassan ran 4:12.33 in 2019 before Kipyegon improved it by several seconds to the current mark of 4:07.64.

“Based on whether the rate of progression is forecasted from 1921, 1960 or 1990,” the Exeter University team propose, “the first women’s sub four-minute mile is projected to occur in 2030, 2038 or 2065, respectively.”

Kipyegon will clearly enjoy multiple advantages compared to female middle-distance running pioneers such as Leather. When the latter broke the five-minute barrier she was only training three or four times per week, raced in heavy leather spikes on a cinder track and had no pacemakers.

Yet Kipyegon benefits from hi-tech Nike super-spikes, state-of-the-art synthetic tracks, far greater volumes of training – much of which is at altitude – an array of supplements such as caffeine, beetroot juice and bi-carb, plus of course pacing help from Wavelight technology and an array of hares that will presumably accompany her almost entirely to the finish line in Paris.

Exeter University’s paper, for example, says: “It has been estimated that drafting behind pacemakers might contribute to a saving of three to four seconds over the mile at four-minute-mile pace.”

So where can Kipyegon find even further improvements? For starters, Jones feels there was room for more when she set her current record of 4:07.64. We also discuss “priming”, where athletes include a hard effort of running at race pace as part of their warm-up.

“I’m not sure Faith maybe has done much of this,” says Jones. “You’ll know that if you do a series of 400m reps, for example, the second rep often feels a little better than the first. Yet for some reason we’ve been reluctant to apply this to a race warm-up.”

Jones also feels that the woman who eventually breaks four minutes for the mile could come from an 800m background so that they’ve got that ‘buffer’ and can handle the (60sec/400m) pace with relative ease. “Faith has ‘only’ run 1:57,” he says, “but she doesn’t race 800m very often and I think she could have run quicker if she turned her attention to it.”

I ask Jones what the single biggest thing he would do if he could go back in time and try to improve on his 4:05 mile? With little hesitation he says: “Training!” Specifically, he refers to more speedwork and race-specific workouts as he was more focused on longer distances at the time.

Not surprisingly Nike do not want to give away all their secrets ahead of the Breaking Four event, so Jones and Osborne are naturally a little coy when talking about what might happen on the day. They even admit they do not know “everything” themselves about what is going to unfold and this simply adds to the intrigue.

What we do know is that there is considerable momentum right now in the women’s mile. In their paper, they point out that the number of women who have broken four minutes for 1500m has more than doubled in the last five years (51 women from 2020-2024) compared to the preceding 10 years (21 from 2010-2019). “Accordingly,” they say, “more women than ever before are running fast times for middle-distance events, thus increasing the probability that a sub four-minute mile could be on the horizon.”

They also know that they are working with an extraordinary athlete who, like marathon star Kipchoge from her own training group, is capable of remarkable things. When they visited the Nike headquarters a few months ago, Osborne says it was “surreal” to meet arguably the greatest female middle-distance runner in history. “I was literally rubbing shoulders with her,” she says.

Osborne adds: “As a middle-distance runner myself, it’s a huge privilege to use my research to try to help Faith in her attempt to become the first female sub four-minute miler.”