Reducing carbon foot sprints

As someone who struggles to run for a bus, the achievements of Eliud Kipchoge and Brigid Kosgei border on the miraculous.

In October last year, the two Kenyan athletes broke, respectively, the two-hour marathon barrier, and the women’s marathon world record.

The casual viewer might not have taken much notice of the trainers they were wearing. But their decision to wear Alphaflys and Next% – both manufactured and designed by Nike – generated fierce debate around the question of unfair advantage, and whether the use of the trainers constitutes ‘mechanical doping’; or, conversely, whether they are an innovation to be celebrated. In response to this debate, last week, World Athletics decided that there needs to be limits on the future competitive use of the trainers.

But before looking at those limits, it might be worth gently jogging through what’s so special about them.

How do the trainers help improve performance?

The trainers can improve an athlete’s running economy by 4-5%. Over a marathon, this would equate to around a 90-second advantage for elite male athletes. Writing in The Times last year, one sports scientist indicated that laboratory studies have found that athletes reduce their oxygen use by 2.7-4.2% when wearing the shoes, with commensurate performance improvements. These improvements are aided through how the shoes are engineered and their layers of carbon fibre plates, cushioning pods, and midsole foam. (An article published last year by Dr Thomas Allen gives a good overview of the science behind the trainers.)

The trainers cost around £240. But, for professional athletes, this cost isn’t why some competitors can’t wear them: they can’t wear them because they are sponsored by other sports brands, so are barred from doing so (Herpassa Negasa – an Ethiopian long-distance runner – even painted three stripes over a pair of Nike Vaporfly shoes so that he could run in them, but not lose his Adidas sponsorship). Competitors argue that Nike-sponsored athletes therefore enjoy an unfair advantage in competition.

Debates on the advantage conferred by these types of trainers is not the first that has focused on sports equipment. After the 2008 Beijing Olympics, swimmers were no longer allowed to wear full body suits that significantly reduced drag after FINA – the international federation that governs swimming and other water sports – voted overwhelmingly to ban their use in competition. In some quarters, their use was referred to as ‘doping on a hanger’.

World Athletics’ response

Like FINA, World Athletics have had to respond to the disquiet the use of the sportswear has raised among athletes, and, on 31 January, it published a statement on the future regulation of the trainers.

The governing body made its decision in the light of its current guidance, which states: “shoes must not be constructed so as to give athletes any unfair assistance or advantage – and any type of shoe used must be reasonably available to all in the spirit of the universality of athletics”.

Its new decision adds a qualification to the latter: “To meet that requirement, any shoe that is first introduced after 30 April 2020 may not be used in competition unless and until it has been available for purchase by any athlete on the open retail market… for at least four months prior to that competition. Any shoe that does not meet this requirement is deemed a prototype and may not be used in competition.”

In a statement accompanying the rule change, the organisation said, that “there is sufficient evidence to raise concerns that the integrity of the sport might be threatened by the recent developments in shoe technology.”

The statement also declared an indefinite moratorium on shoes with a sole over 40mm thick, and those that contain more than one rigid plate or blade (of any material, including carbon fibre). As a result, the AlphaFly trainers worn by Kipchoge when he broke the two-hour marathon barrier are now banned. The Vaporfly trainers meet the requirements and would not be banned. As a non-runner (other than, reluctantly, for that bus), for me this feels like a decision based on fine margins.

What World Athletics’ decision means

As a result of the decision, if Nike, or other sports brands, want to develop new trainers that meet World Athletics’ requirements for this year’s summer Olympics in July, they have around three months to do so. They will need to be on the open market for four months before being allowed in elite competition.

It is also worth pausing over another amendment made by the organisation: “Where World Athletics has reason to believe that a type of shoe or specific technology may not comply with the letter or spirit of the Rules, it may refer the shoe or technology for detailed examination and it may prohibit the use of such shoes or technology in competition pending examination.”

One interesting point here is the reference to the ‘spirit’ of the rules. This might lead to considerations of what constitutes ‘fair play’, and to concerns raised by some who argue that the use of the shoes in competitive athletics distorts the record books, stops ‘fair’ competition because they are only available to professional athletes sponsored by Nike, and is effectively an example of ‘mechanical doping’. In response to the decision, one former Olympian told The Guardian, “Athletes have lost out medals, funding and financial support because Nike have been allowed to break the rules while World Athletics slept and did nothing… It’s the same as doping, it’s simply cheating.”

World Athletics will now establish a working group to guide future research into shoe technology. It would take more than an 800-word blog to anticipate fully the issues it will have to address. So, for the meantime, let’s end with a 40-word story instead…

A friend of mine who thinks fell running is fun, and always seems to come in the top 10 in any cross-country race, recently tried to see how long he could keep up with Kipchoge’s sub-two-hour pace. He lasted 100 metres.

Maybe he was wearing the wrong shoes.

Sports enhancement is one of the topics identified on the Nuffield Council’s recently-published horizon scanning infographic.