In response to controversy over Nike’s Vaporfly running shoe and the bouncy carbon-fiber plate inserted in its sole, World Athletics has instituted new regulations on athletic footwear worn for competition (For background, see SGI Europe – Vol. 31 n°2+3 of Jan. 24).

The governing body for competitive running has declared that, as of April 30, any shoe must have been available commercially, on- or offline, for at least four months before being used in a competition. All other shoes are henceforth deemed to be prototypes and ineligible for competition. This excludes shoes customized for purely aesthetic or medical reasons. Furthermore, road shoes may have soles no more than 40mm thick and track spikes can be no longer than 30mm. Plates or blades in the midsole must be either single and rigid or multiple and lie in the same plane.

World Athletics’ president, Sebastian Coe, says that the body seeks not to regulate the sports shoe market but only to “preserve the integrity of elite competition.” Its ruling prohibits “shoes that go further than what is currently on the market while we investigate further.” World Athletics, which was previously called the International Association of Athletics Federations (IAAF), will be setting up a new working group of biomechanical engineers and others to “guide future research into shoe technology and to assess new shoes that emerge on the market.” New guidelines are expected regarding the construction of track spikes.

The new regulations ban from competition the Nike Alphafly, as it has three carbon plates enclosed in thick, ultra-compressed foam. But the Alphafly’s more commercial cousin, the Vaporfly, currently on sale and equipped with a single plate, has escaped the ban. Runners wearing some version of the Vaporfly claimed 31 of the 36 podium positions in last year’s world championships. As the new rules are not retroactive, no one will be stripped of any victory regardless of shoe. Adidas, Brooks, New Balance, Hoka One One, Saucony, Asics and Mizuno are all working to release new models by April 30 – the new rules’ deadline for eligibility in the Summer Olympics – to compete with Nike’s bouncy breakthrough.

Nike, for its part, will now be releasing a limited number of Vaporfly Next% shoes – the model worn by the Kenyan distance runner Eliud Kipchoge when he became the first human being to run a marathon in less than two hours – by the same April date. And it will be doing the same with two other models: the Air Zoom Alphafly Next%, which has an air pocket in the forefoot, and the Air Zoom Victory, which has spikes.

Two other Nike models slated for release, the Air Zoom Tempo Next% and the Air Zoom Tempo Next Flyease, will not be eligible for competition for the time being. Otherwise, Nike’s Olympic products will include the sustainability-flavored Air Zoom BB NXT, recycled uniforms from Nike SB for skateboarding’s Olympic debut, and Space Hippie casual footwear made from factory scrap and medal-podium uniforms made of recycled polyester, nylon and rubber.