How Running Shoes Changed Over 25 Years

Asics' legendary Gel-Kayano turns 25 with a special edition that highlights how technology has revolutionized footwear.

Asics running shoe exploded diagram
Asics

The future of running shoes takes shape inside a 45,000-square-foot lab in Kobe, Japan. Here, 200 Asics employees research, create, and test new materials in a full-scale biomechanics lab with a climate chamber that can replicate nearly any condition on earth, as well as a materials lab that builds shoes from scratch by creating new chemical mixes and adjusting sole moldings.

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Shoe tech has changed a lot in a quarter-century. As Asics prepares to launch the 25th iteration of its popular running shoe, the , the company let the world see the evolution of shoe materials, design, and technology inside the Asics Institute of Sport Science.

Asics shoemaking lab.
Asics

“The difference between the first shoe and 25 as far as making the shoe is a big [one],” says Toshikazu Kayano, designer of the Kayano 1 through 13. (He is also namesake of the shoe because marketers thought his name was catchy and for an English-speaking audience to pronounce, he tells PopMech.) “The stability is the same, but the designs are quite different and the use of materials are different. If I talk about every single thing that is different, it would take forever.”

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The 1993 original, dubbed the Gel-Kayano Trainer, launched with two different styles of gel in the rearfoot and forefoot. It included suede overlays, albeit with some mesh. It was typical of the early days of stability running with a weight that would be unheard of in today’s shoes. By 2000, Asics’ sixth version took on a new shape to absorb impacts. The 16th style, in 2010, aimed to stabilize a runner’s foot by keeping it straight while he or she ran. In 2016, the 23rd version introduced a new FlyteFoam that was 55 percent lighter than the industry standard.

Asics running track
Asics

For the 25th anniversary model, designers dipped further into the research of the Kobe lab and created two new styles of FlyteFoam—Lyte and Propel—to merge with gel. The result is a full evolution of running shoe that goes far beyond what was possible in 1993. In the Gel-Kayano 25, launching in June, lab technicians created FlyteFoam Lyte with nanofibers between air bubbles—200 times thinner than the previous use of microfibers—for a 20 percent enhancement in strength and durability while creating a lighter product.

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“In normal midsoles, if you try to make it light, the strength and durability will decrease,” says Junichiro Tateishi, footwear material development team manager. “That is the problem we had to solve. Because (researchers) were able to put nanofibers in between the air bubbles, it keeps the foam light but with no reduction to the strength or durability. It allows longer runs.”

With Flyte in the rearfoot, shifting ingredient and chemical ratios allowed the creation of Propel for a different feel in the forefoot, with 50 percent more responsiveness and 39 percent more durability than conventional EVA foam. “During the research and development process,” Tateishi says, “we were inspired by the materials in a bouncy ball.”

"If you try to make it light, the strength and durability will decrease.”

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The Gel-Kayano 25, now under 12 ounces in weight for a men’s version, still includes gel materials in the rear and forefoot for shock absorption.

Most shoe companies ship material creation to chemical companies, making Asics unique in that they develop all their own materials and design their shoes in the same facility. Since the lab opened in Kobe in 1990 and the original Kayano launched in 1993, that relationship between materials and design continues to evolve—with nanofiber-style changes.


Follow Tim Newcomb on Twitter at @tdnewcomb.

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