CNN  — 

A range of high-tech Nike shoes which have revolutionized running have escaped a ban, but advanced prototypes and trainers with thick soles and several carbon fiber plates to boost their spring are to be outlawed in competition in a bid to preserve the integrity of athletics.

Times have been toppling in long distance running races in recent years and critics say some cutting-edge trainers are artificially boosting performances.

A World Athletics review panel has investigated the technology in a range of leading trainers and has passed Nike’s controversial Vaporfly range, but it has instigated an “indefinite moratorium” on any shoes with soles thicker than 40mm or with more than one rigid plate embedded in the shoe to enhance its spring.

From April 30, it will also ban from competition any shoes that have not been on public sale for four months.

The new rules mean the exclusive Nike prototype shoes dubbed the Alphafly, worn by Eliud Kipchoge when he became the first person to run a sub-two hour marathon, would now be deemed non compliant.

“Where World Athletics has reason to believe that a type of shoe or specific technology may not be compliant with the rules or the spirit of the rules, it may submit the shoe or technology for study and may prohibit the use of the shoe or technology while it is under examination,” said a World Athletics statement Friday.

NEW YORK, NEW YORK - NOVEMBER 03: Geoffrey Kamworor and Joyciline Jepkosgei of Kenya pose with the Kenyan flag after winning the Mens' and Womens' Division of the 2019 TCS New York City Marathon on November 03, 2019 in New York City. (Photo by Sarah Stier/Getty Images)
Kenyan runners dominate 2019 New York City Marathon
01:10 - Source: CNN


Nike launched its Vaporfly 4% shoe in 2016 and it quickly became a gamechanger in running.

A study in the journal Sports Medicine in 2017 suggested the shoes, with thick soles and a carbon fiber plate, offered a boost in running economy – the amount of work a runner must do at a given speed – of about 4% compared with another Nike model and a top trainer from Adidas.

A New York Times study in 2018 and another independent review in February 2019 confirmed the findings. According to the New York Times, the top five fastest men’s marathon times in history have been set by runners in Vaporflys.

Kenya’s Brigid Kosgei wore Nike’s publicly available Vaporfly Next% when she beat Paula Radcliffe’s 16-year-old women’s marathon world record last year. Other manufacturers have since launched their own versions of the revolutionary shoes.

World Athletics’ panel, which included technical, scientific and legal experts as well as athlete representatives, found the new trainers “may provide a performance advantage and there is sufficient evidence to raise concerns that the integrity of the sport might be threatened by the recent developments in shoe technology.”

It added that further research will be undertaken with biomechanics specialists and other experts to assess any new shoes, with manufacturers invited to take part in the process.

Kenya's Eliud Kipchoge became the first person to run a marathon in under two hours.

World Athletics president Sebastian Coe said it was not his organization’s place to “regulate the entire sports shoe market,” though he added it should “preserve the integrity of elite competition.”

“As we enter the Olympic year, we don’t believe we can rule out shoes that have been generally available for a considerable period of time, but we can draw a line by prohibiting the use of shoes that go further than what is currently on the market while we investigate further,” he said.

“I believe these new rules strike the right balance by offering certainty to athletes and manufacturers as they prepare for the Tokyo 2020 Olympic Games, while addressing the concerns that have been raised about shoe technology.

“If further evidence becomes available that indicates we need to tighten up these rules, we reserve the right to do that to protect our sport.”

Kipchoge likened running a sub-two hour marathon to Neil Armstrong’s historic moon landing in 1969 and the Kenyan sees nothing wrong with the advancement in shoe design.

“They are fair,” he told the Telegraph newspaper. “I trained hard. Technology is growing and we can’t deny it – we must go with technology.”

However, British Olympic marathon runner Mara Yamauchi believes allowing a technological arms race in shoes is straying into dangerous territory for the sport.

“If they say doping is not allowed because it’s performance enhancing but we’re OK with these shoes which are also performance enhancing, there’s a bit of inconsistency there,” she told the BBC ahead of World Athletics’ decision.

“What we’re getting into now is not who is the best athlete, but who has got the best shoes on.”

Swimming is another sport that has had to contend with the consequences of technological improvements.

At the Beijing Olympics in 2008, 94% of all swimming races were won by athletes wearing Speedo’s LZR Racer swimsuits, according to Time Magazine.

After 17 world records fell at the European Short Course Championships later that year, the International Swimming Federation (FINA) changed its rules regarding the length and material of swimsuits.

Kenya's Brigid Kosgei won the Chiacgo Marathon in a new world record of 2:14.04 in October.

“We’re talking about performance integrity,” said respected sports scientist Professor Ross Tucker, talking to CNN ahead of Kipchoge’s sub-two-hour attempt in October.

“Is Kipchoge an outlier of immense athletic potential? Or is he a simply a very good runner who is benefiting from the immense improvements that his shoes provide? Perhaps both.

“But the point is we don’t know with absolute certainty. Running, especially marathon running, is supposed to be the purest thing humans put themselves through. It’s just about feet, legs, lungs, heart and brain. These shoes create the same problems that doping throws up.”