There has been no shortage of excitement in marathon running this year.
At the 2023 Berlin Marathon, Tigst Assefa of Ethiopia shattered the women’s marathon world record by over two minutes. Assefa ran the 26.2 miles in 2:11:53, bettering the previous record of 2:14:04 set by Brigid Kosgei of Kenya at the 2019 Chicago Marathon.
After crossing the line in Berlin, Assefa can be seen holding her race shoe in the air and kissing it. The shoe she was wearing during her record-breaking run was some of Adidas’ latest technology, the Adidas Adizero Adios Pro Evo 1.
The Adidas shoe quickly made headlines as potentially the fastest shoe out there.
Weeks later, Kelvin Kiptum of Kenya took down the men’s marathon world record at the 2023 Chicago Marathon. Running a 2:00:35, he broke the previous record held by fellow Kenyan Eliud Kipchoge of 2:01:09.
On his feet as he crossed the line, a new Nike prototype that has yet to be released to the public, the Nike Alphafly 3. This was the same shoe Eliud Kipchoge wore as he took his fifth victory at the Berlin Marathon.
The battle of the “super shoes” had begun.
The Science Behind The Single-Use Adidas Super Shoe
When developing the Adidas Adizero Adios Pro Evo 1, the company wanted to make the shoe as light as possible. A 2016 study by the University of Colorado Boulder found that for every 100 grams removed from a shoe, runners ran 1% faster.
Every percent matters when your goal is to break a world record.
Adidas made their record-breaking shoe 40% lighter than their previous top-tier race shoe. The Adidas Adizero Adios Pro 3 weighs 218 grams. The new Pro Evo 1 weighs a mere 138 grams, an 80-gram, and over 60% weight saving.
A significant improvement to the new Pro Evo 1 was in its “Lightstrike Pro Foam,” as they manufacture it using a new non-compression molding process.The improvements reduce significant weight, provide a better energy return, and improve the running economy.
The Adidas Adizero Adios Pro Evo 1 also features a new forefoot design. It incorporates a rocker plate that is 60% of the shoe’s length and has been proven to improve a runner’s efficiency.
Additional weight savings come from the shoe’s evolved upper and outsole. The upper now features a lightweight mesh, and the outsole is made of a lightweight rubber but does not compromise traction.
Finally, the shoe features ENERGYRODS carbon rods. Carbon fiber has become common in many race shoes as it increases energy return with each step.
The catch with the new Adidas Adizero Adios Pro Evo 1 is that they are only intended for use in a single marathon. The significant weight savings have also significantly reduced the robustness of the shoe.
It is no doubt a fast shoe, but with a steep price of $500, many question whether the high-tech innovations are worth its limited use.
The Science Behind Nike’s Unreleased Prototype
Nike has consistently been at the forefront of race shoe development, and the latest Nike Alphafly 3 prototype may be their fastest shoe yet.
Nike says continuous developments to their foam are key and claims that the Nike Alphafly 3 features their “springiest foam yet,” the ZoomX foam.
Nike’s ZoomX foam is a combination of a proprietary polyether block amide (PEBA) and thermoplastic elastomer (flexible plastic).
The benefit of PEBA is it’s capacity for precise tuning to adjust the foam to be made softer or firmer, bouncier or more rigid, to perfection.
“Everyone at the time made a huge deal about this carbon-fiber plate, but that foam is magic,” said Carrie Dimoff, director of innovation at Nike and leads the Alphafly development team.
In their latest Alphafly prototype, Nike started considering incorporating their Nike Zoom Air technology. This is Nike’s trademark air-filled cushioning.
Researchers working on the latest Alphafly believe these air pods could provide better energy returns than even their best foam. Tests in Nike’s energy return chamber found that energy return from the air cushions was upwards of 90%.
Combining their innovative ZoomX foam and Zoom Air technology, Nike built the shape of the shoe around that.
Research and development on the Nike Alphafly team combine laboratory testing and athlete testing when perfecting the shape of the shoe, combining the most efficient shape with what athletes find most comfortable.
The Alphafly 3 prototype also featured a full-length carbon plate, which has become almost standard practice in racing shoes.
Nike’s carbon fiber plate features six slits at the forefoot. According to Dimoff, this was shown to reduce the load and work that the joint must take on and encourage the load to go through the forefoot.
Is There A Superior Super Shoe?
With records getting faster, it raises the question of how much of a role shoe technology plays in a runner’s performance.
There is an undoubted benefit to lacing up super shoes when trying to score a personal best, but at what point does the technology take away from the human feat?