91������

On May 6, 1954, a lanky medical student named Roger Bannister pushed through the finishing tape at Iffley Road track in Oxford, England, and collapsed into the arms of friends after becoming the first human to run a mile in less than four minutes.

Roger Bannister was the first human to run a mile in less than four minutes. (Credit: United Press International/Wikimedia)

The milestone cracked open a world of possibility for male athletes.

“It was the running equivalent to summiting Mount Everest for the first time,” said 91������ Integrative Physiology Professor Rodger Kram. “Prior to Bannister, it was considered impossible—beyond the limits of human physiology.”

Seven decades later, a female runner has yet to follow in Bannister’s footsteps, and some have questioned, as they did with males in the 1950s, whether it’s possible. A new study published this week by Kram and his colleagues suggests that with the right strategically timed and placed pacers, the answer is yes— and Kenyan Olympian Faith Kipyegon is on the brink of doing it.

The study was published this week in the journal Royal Society Open Science.

“We found that if everything went right, under a couple of different drafting scenarios, she could break the 4-minute barrier,” said co-author Shalaya Kipp, an Olympic middle-distance runner who earned her master’s degree in Kram’s lab. “It’s extremely exciting that we are now talking about, and studying, the limits of female human performance, too.”

From ‘Breaking 2’ to ‘Breaking 4’

In 2016, Kram’s lab calculated what was required for a man to break the fabled two-hour marathon barrier.

He and his students determined that, along with intense training, state-of-the-art shoes and an ideal course and weather conditions, drafting—running behind or in front of another runner to reduce air resistance—was key.

Informed in part by their research, Nike hosted the Breaking2 Project in May 2017 to create those conditions for Kenyan marathoner Eliud Kipchoge. Kipchoge narrowly missed his goal that day but nailed it in a similarly staged race in Vienna in 2019.

Four years later, Kram watched with interest as Kenyan runner Faith Kipyegon crushed record after record—the women’s 1,500 meter; the 5,000 meter and the mile—in less than two months, all while raising her daughter.

After watching Kipyegon smash the mile world record for women with a time of four minutes, 7.64 seconds, Kram reached for his calculator.

“I realized she was just a hair over 3% off” from breaking the four-minute mile, he said.

Coincidentally, when his team first started doing their research, the marathon world record holder was about 3% shy of a two-hour marathon.

An idea was born. Kram and his former students, now spread out at research institutions around the world, reconvened—this time to explore the limits of female human performance.

The power of drafting

Run alone, even on a still day, and air molecules bump into you as you move through them, slowing you down. Run in the shadow of a pacer or, better yet, with runners in front and back, and you use less energy.

“The runner in front is literally pushing the air molecules out of the way,” said Kram.

At a breakneck four-minute-mile pace, a runner of Kipyegon’s size must overcome a surprisingly large air resistance force—about 2% of her body weight. The team previously determined that completely eliminating that force would reduce the energy required by about 12%, allowing her to run even faster.

“Anyone from top elite to lower-level runners can benefit from adopting the optimal drafting formation for as much of their race as they can,” said Edson Soares da Silva, first author on the new paper.

For instance, da Silva calculated that a 125-pound, 5-foot-7 female runner who typically runs about a 3:35-minute marathon could improve her time by as much as five minutes.

A magic number

For the new study, the team pored over video of in Monaco. The wind was dead calm. A slight humidity (which reduces air resistance) hung in the air, and she was wearing state-of-the-art shoes.

But her pacers ran too fast at first, said Kram, letting the gap between them and her widen. By the last lap, her pacers had dropped out and she was on her own.

Ideally, he said, one female pacer would be perfectly spaced in front, another in back, for the first half mile; then another fresh-legged pair would step in to take their place at the half-mile point. Collectively, previous research suggests, they could cut air resistance by 76%. Using that value, the team calculated her projected finish time: Remarkably, 3:59.37—the same time Bannister hit in 1954.

“We didn’t cook these numbers,” joked Kram. “We saw that and just smiled.”

Inspiring scientists and runners

Kipp, now a postdoctoral researcher at the Mayo Clinic, stresses that their study, like most in the field of exercise physiology, comes with a caveat: Their calculations were based on previous studies that exclusively involved men.

The authors hope their paper will help spark more interest in studying the physiology of female athletes. If Kipyegon is successful, they say, it could inspire lots of people, whether their goal is to lose a few pounds or finish their first 5K.

“It would show that things people have told you are impossible may actually be possible,” said Kram.

He recently sent a copy of the paper to Kipyegon, her coaches and her sponsors at Nike, floating the idea of another staged race, similar to Breaking2.

“Hopefully,” the last line of the paper reads, “Ms. Kipyegon can test our prediction on the track.”