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Professional runner Faith Kipyegon in her attempt to break the four-minute mile earlier this year.��

In June 2025, during a Nike-sponsored event, world champion and Kenyan middle- and long-distance runner Faith Kipyegon�� to break the four-minute mile barrier. She finished just over the goal with a time of 4:06.42.

But a �鶹��Ѱ�����Boulder lab calculated that it is possible to break the four-minute barrier. �鶹��Ѱ�����physiologist Rodger Kram, who focuses on biomechanics involved with human locomotion, was part of the team that helped Kenyan long-distance runner Eliud Kipchoge historically break the��two-hour marathon in 2019. While Kram was not directly involved in the Kipyegon attempt, his lab published a study earlier this year that found a champion runner like Kipyegon could clock a time of 3:59.37 under ideal conditions. Strategies include coordinated pacing and drafting, which involves a runner following closely behind pacers to reduce air resistance.

Kram and his team, Edson Soares da Silva, Wouter Hoogkamer and��Shalaya Kipp (IntPhys’14; MS’17), also calculated that rotating pacers — runners who set a steady speed to help others reach a goaltime and block the wind — could have provided an elite racer with just enough of an edge to dip under the barrier.

Nike’s execution this year took a different approach.

“They used 13 pacers in a very unusual formation,” said Kram. “Our model involved only two pacers at a time.”

Still, Kram believes the four-minute mile barrier will fall.

“I still think it’s possible, with two teams of female pacers who trade out halfway,” he said.

Royal Society Open Science published Kram’s�� in February 2025.

What’s next for Kram? “We’re cooking up some outrageous next experiments,” he said. “But they’re top secret for now.”

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Photo by Christophe Ena/The Associated Press