No sooner had Sabastian Sawe broken the tape at the London Marathon than the Kenyan was posing for photos, proudly holding up his Adidas shoe, with “1:59:30” and “WR” written along the sole in black ink.
History had been made, a significant barrier surpassed, the first legal sub-two-hour marathon. He did not just break the world record, he obliterated it, beating Kelvin Kiptum’s mark (2:00:35 at the 2023 Chicago Marathon) by more than a minute. Yomif Kejelcha, coming home second, also ran under two hours, finishing just 11 seconds behind. Tigst Assefa lowered her own world record by nine seconds (to 2:15:41) in the women’s race.
All three are Adidas athletes and all raced in the Pro Evo 3. It was an incredible debut for a shoe that Adidas says is the lightest and best it has made — testing data shows 1.6 percent running economy improvements compared to the Pro Evo 2.
Stephan Scholten, the vice president of product in Adidas’ running department, says the design came from “unreasonable ambition.” Adidas’ engineers wanted to create something the marathon had never seen before: a super lightweight shoe that delivered exceptional energy return. “Actual magic,” is how Scholten described it to The Athletic over a video call from Adidas HQ in Herzogenaurach, Germany.
He watched the race on TV at home with his children. “I was on the phone with our GM all the time and we were like, ‘We’ll do it, it will happen’. Everyone went bonkers,” he said.
“What we’re trying to do is help athletes perform at their very best and achieve the impossible. In the truest sense, this is one of the few times when we could actually help do this.”
Sabastian Sawe celebrates crossing the line at the London Marathon in April. (Alex Davidson / Getty Images)
Three years of work had gone into this. The Pro Evo range was launched in late 2023 and has dominated the roads. The first two iterations were worn for seven wins at major marathons in 2025. That design was already one of the lightest (137g) but they wanted to reduce it to “two digits,” Scholten said.
Adidas made changes based on athlete testing — including Sawe and Assefa, both at their training camps and at HQ — to make it lighter. More than a dozen prototypes were made.
“It’s always a very iterative process,” Scholten added. “We needed to change the geometry of our foam and the setup of the stiffening element.” By altering the “formulation” of the foam, they reduced its weight by 50 percent and increased forefoot energy return by 11 percent.
“We could always go softer and softer, but then the support and the energy returned will suffer,” he explained, discussing the design trade-offs and the quest for the “perfect balance.”
The other key element was moving from the energy rods — which Adidas used as its plate equivalent in the first two Pro Evo iterations — to a carbon rim around the perimeter. Scholten explained the in-house discussions. “We were thinking: How do we maximise the foam underfoot?”
The redesign made the new Pro Evo 30 percent lighter than its predecessor. It also affirmed the consensus among researchers: That the carbon plate has been a supportive element, with improvements to foam being the difference-maker.
Angus Wardlaw was formerly a shoe engineer at Adidas in the 2010s, part of the team that pioneered Boost, which pioneered modern midsole foam technology.
“This product is engineered, as well as designed,” he said of the Pro Evo 3. “The midsole is softer than everything else and they’ve no plate under the load (in the middle of the foot). So I reckon it can compress way more, and the energy return is high, they get more back. This is the breakthrough.”
He compared it, functionally, to a spring, before pointing out that Puma had success in 2025 with a similar engineering approach. Its Fast-R 3 shoe, released last April, outperformed leading Nike and Adidas shoes because of market-leading foam and a clever, computer-modelled design. Puma calculated where it could take chunks out of the foam to save weight without compromising performance.
The competition, Wardlaw explained, has changed because World Athletics, the sport’s governing body, limits the sole thickness of road shoes to 40mm. With almost every brand already pushing that limit, the challenge is no longer making the shoe thicker. It is about maximising compression and building the most efficient spring possible within the rules — a shoe that stores more energy and gives more of it back to the athlete.
For completeness, Wardlaw lists the components: “The reason it’s the fastest in the world is it weighs less than 100g, it’s got super-high energy return, it’s super soft, so it’s got this vertical compression. It still has the carbon bending and the continental rubber outsole, which is the best (on the market).”
Tigst Assefa is also an Adidas athlete. (Alex Davidson / Getty Images)
Adidas’ manufacturing is impressive, too. Computer numerical control (CNC) engineering uses a toolpath to cut the foam precisely, ensuring they get the best properties of the foam without treating or reshaping it, a common problem that harms performance. “This is unsqueezed — it is foam in its natural, purest form,” Wardlaw said.
Scholten explained how Adidas has “precisely tuned” the forefoot stiffness, deliberately stopping the carbon rim short of the toes, leaving only foam to increase compression as athletes push off into the next step. They put just as much focus into the heel, including a “small landing pad” to accommodate fatigue.
“Towards the second half of the marathon, even our fastest athletes don’t have the perfect gait anymore,” Scholten added. “(The design) allows them to land a bit more on the mid-foot without coming in too quickly and going into this over-pronation that you would (often) see towards the last 5km (3.1 miles) or 10km. We can maintain a very efficient gait cycle.”
Sawe demonstrated Scholten’s point at the 18.6-mile (30km) mark. That was when the Kenyan made the decisive move to break away from Jacob Kiplimo, who had been considered Sawe’s main rival but finished third. His final two full 5km splits, ran with Kejelcha, were his quickest of the entire race, both sub-14 minutes, and turned a 2:01 projected finish into 1:59.
“They did an incredible job,” Sawe told The Athletic of Adidas and the Pro Evo 3 at the athlete hotel the day after his world record. “It’s the best shoe ever now — very light, so supportive, very comfortable.”
He felt the propulsive benefits and said he first ran in prototypes last summer. “Finally, I could use it in a race.”
Kejelcha had a similar assessment. “It’s very thin, it feels faster, I don’t know, but it’s different,” he told reporters in the mixed zone post-race, still smiling.
Three versions of the Pro Evo 3 have been approved for road races by World Athletics. One of those is an off-the-shelf model, while there are two other development types. All three look the same and Scholten said they are “not significantly” different in their engineering. Instead, it was a “timing component” as Adidas first tried to target the Tokyo Marathon in early March.
The major critique of the Pro Evo 3s, as with all modern super shoes, is their sustainability, particularly when they retail for $500.
“We’ve put the shoes through a very rigorous testing, but these are built for race day only,” Scholten said. He added with “full transparency” that they have a short life cycle of “a couple of marathons.”
Adidas lost the battle in 2019 when Eliud Kipchoge ran 1:59:35 in Nike Alphaflys at the record-ineligible INEOS challenge. But Adidas won the war because it developed the first shoe to break the two-hour barrier in an open marathon, a feat achieved thanks to a perfect storm: high-quality athletes, excellent pacing and pack running, good weather conditions, and, significantly, the Pro Evo 3s.
“It’s a great moment for us as a company but an ever greater moment for the sport itself,” Scholten said. “It’s why we go to work every day.”