Why banning Nike's ZoomX Vaporfly Next% would be a mistake

27 January 2020 | Applicable law: US

World Athletics (formerly known as the IAAF) are, apparently, on the verge of a dramatic U-turn that would ban athletes from wearing Nike's Vaporfly 4% / ZoomX Vaporfly Next% running shoes. Despite being widely used by elite road runners over the past few years – including marathon world-record holders Eliud Kipchoge and Brigid Kosgei – World Athletics is expected to introduce new rules in February 2020 which would, in effect, ban the controversial footwear.

Why are the Nike Vaporfly's so controversial?

The Nike Vaporfly shoes have two defining features:

  1. a super-thick sole made from a lightweight, soft and responsive foam (known as 'ZoomX') that apparently delivers 85% energy return; and

  2. a carbon-fibre plate embedded in the midsole (known as the 'launchpad') that apparently acts as a propulsion lever and helps prevent energy loss in toe bends.

According to Nike, this combination – together with the fact that the shoes are incredibly lightweight – reduces fatigue and increases running efficiency. According to critics, the shoes provide a performance enhancing "trampoline effect", provide Nike-sponsored athletes with an unfair competitive advantage, and amount to "technological doping".

What do the rules currently allow?

As things stand, footwear regulation in World Athletics road running competitions is surprisingly permissive. The rules merely provide that shoes:

  1. "must not be constructed so as to give athletes any unfair assistance or advantage"; and

  2. "be reasonably available to all" (but personalised shoes which have been adapted "to suit the characteristic of a particular athlete's foot" are expressly permitted).

The rules do not currently regulate or limit sole thickness, construction materials, heel-to-toe drop dimensions, or any other technical aspect of footwear.

Why is World Athletics expected to change the rules?

The technological committee of World Athletics has reportedly been studying Nike's Vaporfly shoes since 2017. To date, they have taken the view that running shoes shall not be considered to provide "unfair assistance or advantage" unless they are motor-assisted. This approach is directly comparable to cycling where technological innovation is encouraged, but motor-assistance is prohibited.

World Athletics now, however, looks to have been persuaded to change its stance following complaints by non-Nike-sponsored athletes / rival brands. Such lobbying has no doubt highlighted the fact that, whilst advancements in athletics tend to be incremental, the five fastest marathon times in history have all been set recently by athletes wearing Nike Vaporfly shoes, as well as the first (unofficial) sub-2 hour marathon in October 2019 during which Kipchoge wore an unreleased version of the Vaporfly known as the “Nike alphaFLY" (with an even thicker midsole).

How will the rules change?

It is widely expected that World Athletics will introduce rules which (i) limit the thickness of soles, and (ii) prohibit the use of carbon-fibre plates. The move would – in part – follow the approaches taken in high jump / long jump (where sole size is already regulated) and in swimming (where the international swimming federation introduced a limit on the length of swimsuits in 2009 after 98% of all swim medals won at the 2008 Beijing Olympics were won by athletes wearing Speedo's LZR Racer full-body swimsuit).

The new rules would, however, be misguided for several reasons:

  1. they will represent a finding that World Athletics now believes that certain Nike shoes do provide athletes with an unfair advantage (despite previously taking the opposite view);

  2. they will ban both Nike's Vaporfly shoes and the shoes from several other rival brands (e.g. Asics, New Balance, Hoka, Sketchers, etc. – all of which combine carbon-fibre plates with thick foam soles) – if other manufacturers already utilise similar technology to Nike, what unfair advantage are Nike-sponsored athletes actually receiving?; and

  3. they will simply incentivise Nike and other manufactures to achieve the same results (i.e. increased running efficiency) with slightly different materials (e.g. a different foam to reduce sole thickness, and an alternative light-weight, rigid material to replace the carbon-fibre plate).

If greater regulation is deemed desirable, the better approach would be to regulate the energy return that athletes can lawfully receive from running shoes. This would create a regime that prioritises human endeavour and isn't susceptible to rule-avoidance by the use of slightly different materials. Either way, don't expect the rule change to break Nike-sponsored-athletes' dominance anytime soon...

This document (and any information accessed through links in this document) is provided for information purposes only and does not constitute legal advice. Professional legal advice should be obtained before taking or refraining from any action as a result of the contents of this document.


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