Records are falling, complaints are breaking out, the controversy is growing. This time, they are simple running shoes, which have become seven-league boots for those who own them. It is first of all the Kenyan Eliud Kipchoge, who, in his Nike Vaporfly, went under the mythical bar of 2 hours in the marathon, exactly 1h59min40s, world record not approved on October 12th.
A shower of performances, each more impressive than the next, followed. Each time the athletes were wearing similar models. In question ? A carbon fiber plate - or more - slipped into the sole, associated with an air foam. A technological evolution for some, an aid to proscribe for others. The International Athletics Federation opened an investigation on October 17 and may soon ban their use. Explanations on these shoes which make run fast.
Records explode race after race
The day after Kipchoge's unlicensed record, compatriot Brigid Kosgei smashed Paula Radcliffe's old women's marathon record in 2h14min4s, 1 min 21 s better. During the Corrida de Houilles (Yvelines), on December 29, the winner of the men's 10 km race Daniel Ebenyo (27 min 12 s), Jimmy Gressier, who became the second European performer in history (27 min 43 s), or Liv Westphal, new recordwoman from France in the distance (31 min 15 s), also had their feet on the new little candy pink bomb. "When a manufacturer puts several carbon blades in the sole, with air cushions, it is no longer a shoe, it is a spring", reacted Ryan Hall, the record holder of the United States of the half-marathon .
Carbon at the center of the debate
The controversy is not new. The inaugural model of the Vaporfly range was the first to use a carbon plate in 2016. Thus equipped, Kipchoge, Olympic champion in Rio had attempted and missed the passage within two hours on May 6, 2017, on the Monza circuit, in Italy (2:25 s). The latest model sold in the range in April, the Zoom X Vaporfly Next% has seen innovations. Nike has particularly reinforced the cushioning with a more protective foam at the sole and heel. For his new attempt, successful this time last October, the Kenyan used a shoe not yet marketed with three carbon fiber plates.
A rather vague regulation
The International Federation (IAAF which became World Athletics in November), seized by many professional runners who protested against such an advantage brought by a brand, therefore opened an investigation on October 17. Will it reverse its first decision made in May 2017? She then changed her rules to validate the first Nike model with a carbon fiber plate. It is now stipulated: "Shoes must not be constructed in such a way as to give athletes any unfair help or advantage. Any type of model is authorized provided that it is accessible to all in the spirit of the universality of athletics. "
According to the English press, the body could soon again change the rules and ban this model of shoes, notably by limiting the thickness of the sole. The situation is reminiscent of the polyurethane swimming suit in the 2000s. At the 2008 European Short Course Championships, seventeen world records were broken by swimmers wearing the British brand Speedo LZR Racer suit. The International Swimming Federation had finally reacted by banning this kind of wetsuit in competitions in 2010.
The competition is positioned
The new performances of the aces of the pelotons found echo among the amateur runners. The Nike Zoom X Vaporfly Next% is sold at a price of 275 euros. But, beware, this shoe is not made for Sunday jogging. The feet tilted forward do not offer a frankly comfortable position and the effect is not necessarily beneficial for an occasional runner.
Still, the market is huge. Nike's competitors have already launched shoes using similar technologies. Hoka marketed the Carbon X in May. More recently, New Balance launched its first shoe with a carbon plate, the Fuel CellRebel. The process is gaining ground. He has already arrived on the track where some athletes, wearing shoes from Nike, used the first prototypes at the Doha Worlds last September.