Last winter, a study startled the running world when a team of researchers concluded that, under the right circumstances, Kenyan superstar Faith Kipyegon could break a barrier long thought impossible — becoming the first woman to run one mile in less than 4 minutes.
In the coming days, under a worldwide spotlight, that theory will be put to the test.
Kipyegon on Thursday will line up in Paris in a Nike-sponsored race called “Breaking4,” just four laps — and 1,609 meters, to be exact — from history.
If there were ever a runner to make such an attempt, it would be the 31-year-old Kipyegon. A three-time Olympic gold medalist in the 1,500 meters, who holds the world record in the 1,500 meters and formerly held the record at 5,000 meters, as well, she has come closer to the 4-minute barrier than anyone. In 2023, racing in Monaco, Kipyegon smashed the previous world record for the mile by running 4:07.64.
“She’s really stretching your imagination and acceptance of how women can excel in sport,” said Rodger Kram, an associate professor emeritus at the University of Colorado who co-authored the study published in February in the Royal Society of Open Science.
Yet speed alone won’t make up the 7.64-second difference between her personal best and a barrier-breaking achievement — a lifetime in a race as short as the mile. The great variable surrounds how exactly Kipyegon will “draft” off pace-setters around her, thus reducing her aerodynamic drag. How many pacers Nike will use, and what formation they will employ, remains a mystery.
Kipyegon told The Associated Press that “breaking four will really cement my legacy.” Yet breaking four minutes could lead to a wider effect. Half-marathons and marathons have enjoyed a post-pandemic participation boom, but Kram wondered whether Kipyegon’s example could inspire more women to run middle distances.
“To see that, one, we actually want to go after a female record, that’s exciting,” said Shalaya Kipp, a former Olympic distance runner and NCAA champion who co-authored the study. “It’s going to not only draw more females to the sport, but it’s also going to help draw more attention to female physiology and get more research done on females too.
“… That’s not the runner in me, but that’s the scientist in me that gets really excited if we have this. Scientists are going to start working with more female athletes, and that is a big gap we have right now.”
As experts in physiology and kinesiology, Kram, Kipp and their study’s co-authors, Edson Soares da Silva and Wouter Hoogkamer, were already fans of running. But their pursuit of whether a female sub-4 mile was possible began in earnest in 2023 while watching Kipyegon run her 4:07 world record while using pacers for only half the race.
“It really stood out to us that this was a very fast race — a world record, of course — but she had terrible drafting,” said Kipp, a postdoctoral research fellow at the Mayo Clinic. “We’re track nerds, and we watched that, and we’re like, ‘Well, what if? What if?’ And then we were like, we actually could do that math.”
The researchers’ sub-four findings were modeled on a scenario in which Kipyegon would draft off a team of all-female pacers, in part for the gender-breaking symbolism it would represent, Kipp said. In that scenario, the study found that if Kipyegon could stay within about 40 inches behind a pacer in front of her, and 40 inches in front of another behind her — with a new pacing team swapping in halfway through — it would create an aerodynamic “pocket” in which she would face the least wind resistance.
Under those conditions, Kipyegon could run 3:59.37, the paper concluded — the exact time run by Roger Bannister in 1954 when he, using pacers for more than 80% of the race, became the first person to ever break the sub-4 barrier.
Less remembered is that also in 1954, Diane Leather became the first woman to break the 5-minute barrier in the mile. It took more than half a century for the idea of a woman running a sub-4 mile to enter the realm of possibility, however, as training, times and technology all improved.
An inflection point arrived in 2016.
That year, Nike became the first shoe company to combine an exceptionally bouncy new foam with rigid “plates” in their shoes and spikes. Studies have determined such “supershoes” require less effort to run at a given pace by absorbing the impact from each footstrike, allowing runners to rebound quicker. The breakthrough led Nike to design a different moonshot race, dubbed “Breaking2,” in which Kenyan superstar Eliud Kipchoge attempted to become the first person to run a marathon in less than two hours. He came up 25 seconds short during his first try, in 2017. In his second attempt, three years later, Kipchoge ran 1:59.40. The times do not count as an official world record because the carefully tailored attempt did not meet the standards of the sport’s global governing body, but it represented a seismic shift in what was possible all the same.
It was also a sign of things to come.
“We opened the 2016 floodgates,” Kipp said, “and we saw these times dropping.”
Of the 50 fastest miles run by women all-time, 33 have been run since 2016, including 10 of the top 11. The world record of 4:12.56 had stood since 1996 until Sifan Hassan ran 0.23 of a second faster in 2019. Four years later, Kipyegon shattered Hassan’s world record by a stunning 4.69 seconds in Monaco.
In Paris this week, Kipyegon will wear custom-made Nike supershoe spikes as well as a speedsuit and custom bra designed to reduce drag. Kipyegon is unique in that her stride appears effortless, as if floating, Kipp said. Yet what matters most, Kram and Kipp said, is whether Kipyegon has improved at staying tucked in behind her pacers.
Nike did not consult with Kram, Kipp or their research team on the technical details of Kipyegon’s attempt. How the sportswear giant will handle the number and gender of the pacers has led to significant intrigue. Stadiums hosting professional meets feature a metal “rail” on the inside of the first lane, separating the track from the infield. Because Paris’s Stade Charlety has little rubberized track surface inside of the rail, it’s unlikely it will have the space needed to use the type of “full arrowhead” formation it employed in its attempt to help Kipchoge break two hours in the marathon. Kram wonders if Nike will employ a “half arrowhead” or perhaps even the model the researchers studied, with one in front and one behind.
He and Kipp will also be watching for how Kipyegon and her pacers line up at the start; how relaxed she appears while pushing an unprecedented pace; and, nearing the finish, when the pacers will peel away to allow Kipyegon to finish alone.
“I’m going to be watching to make sure that she’s in the pocket, and that the pacers don’t get too excited,” Kram said. “… In the first 200 (meters) you can ruin your chances for the mile. If she goes out and runs 27 (seconds), she’s cooked. She’s got to go out in 29, 29-high.
“If she comes through 1,200 in 3 minutes, I think she’s going to get it. Other people are saying, ‘Oh, that’s when she’s going to die.’ But I believe in our numbers and our calculations.”
Kipchoge and his training partners wore T-shirts featuring “Breaking4” and Kipyegon’s image during training recently.
“It’s been an honor for us to support (Kipyegon) as she prepares to achieve the unthinkable and to break down the barriers of human performance,” Kipchoge wrote on Instagram. “Faith is a true inspiration for our world. If there’s one person to do it, it is you. Go for it!”
The race also comes at a significant moment for Nike itself. The company’s roots are in running — it was founded by a middle-distance runner, Phil Knight, and his collegiate track coach — and more runners finished distance races in 2024 wearing the brand than any other, according to an industry group survey. In recent years, however, Nike’s shelf space and market share among running shoes has been challenged by newcomers such as Hoka and On. Kipyegon’s sub-4 attempt will come on the same day that Nike is scheduled to host a quarterly earnings call.
In the days before Kipyegon’s race, Kram acknowledged having nerves over how the study’s findings would fare in a real-life test. Many of his previous studies had received scant attention from the wider public, he said. February’s sub-4 paper, by comparison, had drawn global attention.
“Even if we don’t go below four, how exciting is it just to have this attempt?” Kipp said. “Is it really going to be a failure if she runs, you know, 4:01, 4:02? It’s still going to be a big deal.
“That’s how Eliud Kipchoge’s first sub-2 (marathon) attempt was. It wasn’t perfect, but it lowered the standard, and it made us realize, if we can get closer we can do it.”
