Paris (AFP)

Mechanical doping or welcome innovation, the Vaporfly shoe from Nike launched athletic equipment manufacturers in a plantar armament race that made as many waves as swimming suits ten years ago.

Revolutionary shoes incorporating a carbon blade in their sole, the running pairs of the Vaporfly range allowed Nike athletes to capture 31 of the 36 places on the podiums of the six main marathons last year.

This quasi monopoly, coupled with the performance of the Kenyan Eliud Kipchoge, passed on October 12, during an experiment in Vienna, under the mythical bar of two hours (1 h 59 min 40 sec) over the distance of the marathon (42.195 km) forced World athletics (ex-IAAF) to react by banning prototypes, capping the size of the soles and limiting the number of carbon blades - Kipchoge's experimental model, the AlphaFly, had three.

- competitors' response -

After the international federation, it is the turn of Nike's competitors to retaliate: in the wake of the brand with the "swoosh", Adidas, Asics, Brooks, Hoka, New Balance and Saucony have unveiled - or will present - their own basketball model using carbon.

Starting point for a technological leap forward or catching up with an inequity? "My belief is that shoes with carbon fiber blades are part of the long-term evolution of running sneakers and the continuous innovation that has been at the center of their development since the early 1970s" , estimates with the AFP the American journalist Brian Metzler, author of "Kicksology: Promotion, Science, Culture and Coolitude of the running shoes".

According to him, these new models "do not artificially create energy but rather maximize the strength and energy that a runner puts naturally in his stride". A feature that makes them "acceptable", says Brian Metzler by putting this in parallel with the evolution of equipment in other sports such as tennis, skiing, cycling, golf and even football.

"The key is that at some point, all competitors must have access to similar or equivalent technology to guarantee a level playing field," he said.

It is not yet won: the competitors wearing "Zoom Vaporfly 4%" or "ZoomX Vaporfly Next%", the latest born from the Eugene (Oregon) firm, run between 4 and 5% faster than the others on the marathon, according to a statistical analysis of the New York Times published in December.

- "absolutely unfair" -

Which makes Amby Burfoot, winner of the Boston Marathon in 1968 and former editor of Runner's World magazine, say that the unannounced introduction of the first Vaporfly of Nike in 2016, in particular to the American Olympic qualifications for the marathon and at the Rio Olympics, was "absolutely unfair".

"This was tantamount to letting a group of pole vaulters use fiberglass when all the others were reduced to using bamboo," said Amby Burfoot, interviewed by AFP.

And it doesn't say that the founders have been fighting on equal terms since: "It was not easy for other shoe manufacturers to catch up with Nike - it took time and trial and error - and we we still do not know to what extent they have closed the gap, "analyzes Geoff Burns, researcher in biomechanics and sports performance at the University of Michigan, consulted by AFP.

Regarding the latest models of the point's competitors, "there is only one or two that could come close to those of Nike," said this expert in running shoes.

"I would be surprised if only one of them was as advantageous as the Vaporfly 4% model, released three years ago, not to mention the new versions", judge Geoff Burns.

- "plus the total Far West" -

"The difference now is that we have rules that somewhat frame the design of the shoes, notes Amby Burfoot. It is no longer the total Wild West. Given the rules of world athletics, it will be difficult for a shoe to stand out in a spectacular way from the others, "wants to believe the ex-marathoner.

The Covid-19 epidemic and its economic consequences may not help reshuffle the cards in this game where Nike is already one step ahead.

All equipment manufacturers will have to make choices to overcome this crisis which has already led to the closure of several factories in Asia, recalls Geoff Burns. In this climate, will the development of a new model of long-distance shoes be a priority?

© 2020 AFP