Two Athletes Smashed a Marathon Milestone, Running 26.2 Miles in Under Two Hours. Here’s the Science Behind Their Achievements
An intense training regimen, good weather conditions, physiology and lightweight shoes probably played a role in their astounding performances during the London Marathon on Sunday
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On April 26, two runners surpassed a mind-blowing milestone: They dashed 26.2 miles to the London Marathon’s finish line in under two hours, making them officially the first people to break the time barrier.
Kenya’s Sabastian Sawe won the race and now holds a world record with a marathon time of 1 hour, 59 minutes and 30 seconds. Ethiopia’s Yomif Kejelcha placed second by running it in 1 hour, 59 minutes and 41 seconds.
Both have made headlines for their achievements—and their Adidas shoes. Here’s how they did it.
As you can probably imagine, preparing for a marathon involves tons of training. Sawe’s coach, Claudio Berardelli, told reporters that in the six weeks leading up to the race, Sawe had been running about 125 miles per week, and he peaked at 150 miles.
Last September, he had been well prepared for the Berlin Marathon, but the late-summer heat prevented his best possible performance, Berardelli said, per the Agence France-Presse. “But when I started to see him running the way he ran before London, I was like, ‘Hey, something special might come out.’”
Quick fact: An earlier sub-two-hour marathon
Kenya’s Eliud Kipchoge technically broke the two-hour mark during a race in Vienna in 2019. However, the marathon was designed for this goal and had favorable running conditions, according to the Associated Press, so it was not an official time.
That reported training volume probably played a big role in Sawe’s performance, and it’s well beyond what most athletes can tolerate, writes Mark Connick, a sports scientist at the Queensland University of Technology in Australia, for the Conversation. Previous research has shown that high training volume done at relatively low intensity is associated with speedier marathon performances.
Additionally, Sawe fueled his body by starting race day with bread, honey and tea, he said during a press conference after the marathon. He consumed carbohydrate drinks and gels throughout the run, allegedly averaging about 115 grams of carbs per hour, per Citius Mag’s Chris Chavez.
Race day weather conditions are also important. Temperatures at this year’s race were cooler than in 2025 and less windy than in 2024, reports the Athletic’s Liam Tharme. At around 9:30 a.m., when the elite men began their run, London was about 55 degrees Fahrenheit, and it reached roughly 60 degrees Fahrenheit by the time they finished.
“We saw the weather would be good, all the conditions were in place,” Ethiopia’s Tigst Assefa said, through a translator, during a press conference after the race, per the outlet. She set the women’s world record in London with a time of 2 hours, 15 minutes and 41 seconds.
Physiology is a vital piece, too. Connick writes that successful marathon runners have three main attributes: an exceptional capacity to intake and use oxygen while running, the ability to maintain most of that capacity for long periods of time and the ability to use less oxygen at a given speed than typical. While we don’t know the details of athletes’ physiology, they probably have these abilities.
Much of the chatter around the sub-two-hour marathon breakers has focused on the runners’ Adidas shoes. Sawe, Kejelcha and Assefa all sported Adizero Adios Pro Evo 3s, which Adidas now calls “humanity’s fastest shoe.” Each weighs less than 3.5 ounces.
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The shoe’s design is all about economy, says Brad Wilkins, an exercise and sport physiologist at the University of Oregon, to Adam Kovac at Scientific American. Padding in the sole is made of ultra-lightweight foam, which keeps the shoes comfortable without making them too heavy. The shoe’s carbon plate—a stiff structure in the sole—puts the runner “kind of in a forward tilt,” he adds. That helps, because an efficient long-distance running gait mostly relies on the front of the foot.
The shoes “increase the springlike capability of the leg by adding, essentially, a spring on your foot,” says Daniel Lieberman, a biologist at Harvard University who studies the evolution of human physical activity, to Scientific American.
The runners have also commended the footwear. “It’s very thin, it feels faster,” Kejelcha said, reports the Athletic. Assefa called them “great shoes for racing, very light,” per the outlet.
When all these factors create a perfect storm, athletes can smash records. And as training regimens and shoe technology improve, runners might get even faster.
“The bar has 100 percent been changed,” Wilkins tells Scientific American. “I think it’ll be very soon where, if you’re not running sub-two hours, you’re no longer in the elite kind of category.”
Editor's note, April 30, 2026: This story has been updated to correct the month of the race.
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