A New Rule Limiting Vaporfly-Like Shoes Is Coming Soon. Maybe.

World Athletics is meeting to decide if it wants to put limits on the Nike Vaporfly and similar shoes. Here's a brief history, and expert perspectives on where we are now.

Any day now, World Athletics (WA) is expected to release the findings of its special working group investigating running-shoe regulations. In other words, should the Nike Vaporfly family and similar shoes be outlawed or restricted?

Anticipation is so high that 10 days ago British newspapers published stories claiming to preview the outcome. The stories contradicted each other. Yes, new rules are coming. No, they aren’t.

The issues are clearly complex, and any new rule won’t come easily. WA, until several months ago known as the International Association of Athletics Federations (IAAF), wants the sport to attract attention. The Nike shoes, and their many fast performances, have certainly done that.

photo: Nike

Unfair Advantage?

The current Competition Rule #143 5.B. states that no shoe can provide an “unfair” advantage and that “Any type of shoe used must be reasonably available to all.”

One view holds that “unfair” means “no wheels, no motors.” And that “type of shoe” are the key words of the second restriction. The logic goes something like this: The new Nike shoes are thick, with a stiff plate in them. Any shoe company can make thick shoes. Any company can put a stiff plate in their shoes. Therefore, anyone can make he same “type of shoe” as Nike. End of argument.

Or not. That’s what the WA working committee is trying to decide. Here’s a brief history of how we got to this point, and what key individuals think World Athletics should do.

Let’s Review

Prior to 2016: Training shoes were generally thick and stiff, and racing shoes were thin and flexible.

February, 2016: At the U.S. Olympic Marathon Trials in Los Angeles, three Nike athletes—Galen Rupp, Amy Cragg, and Shalane Flanagan—made the Olympic team wearing unusually thick Nike shoes. No one knew anything more about these strange, unnamed shoes.

Shalane Flanagan and Amy Cragg LA2016
photo: 101 Degrees West

August, 2016: At the 2016 Rio Olympic Marathon, the top three men finishers all wore the new, unnamed Nike shoe.

May, 2017: Eliud Kipchoge ran an astonishing 2:00:25 in Nike’s Breaking2 exhibition on a car track in Monza, Italy. He wore a thick, rockered shoe named the Vaporfly Elite.

November, 2017: A group of Nike researchers and University of Colorado biomechanists published a paper in Sports Medicine investigating the economy of runners in the Vaporflys vs traditional racing shoes. The Vaporflys conferred approximately a 4 percent advantage (hence the name of the version the public could buy: Vaporfly 4%). A 4 percent reduction in energetic cost is equivalent to roughly 3.4% faster in a marathon—about 4:13 for a 2:04 runner and 5:47 for a 2:50 runner. The tested version of the Vaporfly had a heel height of 31 mm.

September, 2018: Eliud Kipchoge lowered the marathon world record to 2:01:39 in Berlin. He wore Vaporflys.

October, 2018: Sport scientists Kyle Barnes, a researcher at Grand Valley State University in Michigan, published a study in Sports Medicine with results almost identical to the University of Colorado report from November, 2017.

Nike ZoomX Vaporfly NEXT% upper

Nike ZoomX Vaporfly NEXT% / photo: courtesy Nike

April 2019: Nike introduced the Next%—an enhanced Vaporfly 4%. The Next has a heel height of approximately 40 mm.

October, 2019: Kipchoge ran 1:59:40 in the Ineos 1:59 Challenge over an urban loop course in Vienna. He wore a shoe code-named the Alphafly. It appeared to be thicker than either the Vaporfly or the Next. Internet sleuths quickly matched the new shoe to a Nike patent application for an extraordinarily-designed shoe with three carbon plates and cushioned, forefoot pillars. However, there has been no verification that Kipchoge actually wore the shoe from the patent application, or even that such a shoe has actually been produced.

Nike Prototype Racers Kipchoge
Photo: Jed Leicester for The INEOS 1:59 Challenge

October, 2019: The British Journal of Sports Medicine published an editorial by biomechanists Nicholas Tam and Geoff Burns. It advocated that WA should limit the “midsole thickness” of running shoes to 31 mm.

October 13, 2019: Bridgid Kosgei wore Nike Next% and ran 2:14:04 in the Chicago Marathon. This shattered Paula Radcliffe’s 16-year-old world record, 2:15:25, which no woman had come remotely close to since Radcliffe’s run.

October, 2019: When WA began receiving inquiries about the legality of Nike’s shoes, it acknowledged that a “working group” was studying the issue. WA said a finding was expected before the end of the year.

November, 2019: On his blog, podiatrist-biomechanist-shoe consultant Simon Bartold offered a novel reason for the success of Vaporfly-wearing runners. He argued that maybe it’s not about energy return but fatigue-resistance. According to Bartold, the thick midsoles dampen muscle vibrations, which prevents the muscles from growing tired and cranky. This explanation agrees with a real-life observation; Vaporfly marathoners don’t just start fast, they finish even faster, running impressive negative splits.

CIM women's OTQ pace group
CIM women’s OTQ pace group / photo: Luke Webster

November and December 2019: At the Indianapolis and California International marathon races, a high percent of runners who achieved qualifying times for the U.S. Olympic Marathon Trials did so in Nike Vaporfly 4% or Next% shoes.

January, 2020: In Japan’s most famous ekiden race, the Hakone, 84 percent of elite college runners wore Vaporfly 4% or Next% shoes. They set many stage records. In previous Hakones, Japanese runners had preferred minimalist racing shoes from Mizuno and Asics.

January, 2020: A German sports scientist, Helmut Winter, published an analysis of best marathon times (under 2:08 for men, under 2:25 for women) in recent years. He found that 2019 had roughly twice the number of fast times vs other years. The top men were about 1:45 faster, and the top women about 3:00 faster, than in prior years.

January, 2020: World Athletics announced that its working group hoped to file a report by the end of the month.

Where Are We Now?

The U.S Olympic Marathon Trials are a month away, and the Tokyo Olympics will open on July 24. Timing is everything at this point.

If the WA working group recommends a new shoe rule, that proposal must be ratified by the WA’s 26-member Council, which “has responsibility for all decisions … including rules and regulations.” The Council will next meet at the 2020 World Indoor Championships in mid-March in Nanjing, China.

So take the U.S. Marathon Trials off the table. That event will be not just a fantastic competition, as it always is, but the greatest shoe-wars smackdown of all time.

Saucony Endorphin Pro
Saucony Endorphin Pro / photo: 101 Degrees West

Saucony and Hoka have had thick, stiff-plated shoes for a year or so. Other companies are racing to match, or exceed, Nike’s shoes. They’ll all be on the ground in Atlanta on February 29, no holds barred. This includes, in all likelihood, Nike’s own latest innovation, whether Alphafly or other.

It will be the first U.S. Olympic Marathon Trials where the shoe talk may exceed the runner talk. We used to chatter endlessly about race results and training. “Did you hear about his 20 miler with the last five miles at 4:50 pace?” Now it’s going to be: “Have you seen the shoes she’s wearing?”

The WA Council has the power to act with extraordinary swiftness when it deems such action necessary. It would prefer a more measured approach. It would like to give events and athletes a moderate time frame leading up to an actual rule-enforcement date.

The clock is ticking fast toward Tokyo. We don’t know what the Council might think about the urgency of a shoe regulation, if it even decides to adopt one. Asics is a “World Athletics Partner,” but Nike and other shoe companies are deeply ingrained in the business of running, which is WA’s business also. WA’s president, Sebastian Coe, competed for Nike in his racing career, and was a paid Nike consultant for many years afterwards.

Last week I contacted Nike’s media relations department to ask if Nike would comment on the brewing controversy, and if any Nike runners would be wearing the Alphaflys in Atlanta. Nike acknowledged receipt of my questions, but I have not received any answers.

What Should World Athletics Do?

Athletes, managers, and even scientists are largely cautious when speaking about shoe companies. After all, they have friends who run for other shoe sponsors, and they might even hope for a different contract when their next negotiation comes around.

Athletes’ Opinions

A few American runners who aren’t Nike-sponsored have made critical comments at recent NYC Marathons. They seem to favor a more restrictive shoe rule. Last November, Brooks runner Des Linden said: “It is an arms race and it should be a footrace. We should find out who the best athlete is and who can cover 26.2 better than the other person—not who has the newest or greatest technology.”

At the same event, Asics runner Sara Hall said: “I think, honestly, it’s a bummer. It’s a bit of a distraction to our sport right now. I think it would help to have some limits, just like in swimming, or triathlon, or cycling.”

sara hall nycm 2019 PC
photo: Jen Ator

A year earlier, Saucony runner Molly Huddle commented: “I think it’s going to be like the wet suits in swimming. I think we’re still waiting to see which way it goes.”

This week, when I asked Deena Kastor for her thoughts, she responded: “There should be regulation so every company must meet the same standard, or limitations.”

Scientist’s Perspectives

The most informed sports scientists have a nuanced view that’s often not easy to summarize.

In a recent “More isn’t always better” letter to Footwear Science, Hoogkamer wrote that shoes had perhaps already reached their “sweet spot” in terms of midsole thickness. More wouldn’t necessarily be better, he argued. In fact, it could lead to injury and performance problems.

“The scientist in me would not want to limit innovation,” Hoogkamer, now at the University of Massachusetts, wrote in an email. “I wouldn’t want to stop inventive coaches and athletes from pulling out a waffle iron and experimenting. Still, limiting stack height might be an effective way to limit integrated stacks of ultra-warped and ultra-stiff carbon plates embedded in ultra-soft, ultra-responsive and ultra lightweight foam.”

Kyle Barnes, the researcher from Michigan, says: “I think runners wearing Vaporflys have had the field tilted in their favor, but who knows what the other companies have come up with, and how much it will close the gap? Limiting stack height makes sense. I also don’t think athletes should be able to compete in patent-protected technology, though I realize that’s not going to happen.”

Elite ultrarunner Geoff Burns often sounds more like a philosophy student than a biomechanist. He says he fears for the sport’s history if runners and performances of the last 40 years are wiped away by new shoes. He’d like to see a midsole limit set at 28 mm, slightly below what he and Nicholas Tan actually proposed in their BJSM editorial.

“The essence of running is distilled human performance,” Burns observes. “We should remain as true to that as we can. If we minimize the extent to which shoes can enhance a runner’s performance, we also minimize the extent to which shoes determine who wins and who doesn’t.”

A Coach Weighs In

As coach of a strong Hoka sponsored Northern Arizona Elite marathon team that includes leading trials contenders Kellyn Taylor and Scott Fauble, coach Ben Rosario hears shoe buzz every day. He can’t do anything about the rumors, or the wild mix of shoes that will appear in Atlanta. But he needs to keep his runners focused on the job at hand. How can he make sure they don’t get psyched out if they spot Nike Alphaflys in the Marathon Trials?

Scott Fauble and Ben Rosario
photo: Jen Rosario

“We’ve been testing new Hoka shoes that we’ll be wearing in Atlanta,” said Rosario. “We’re excited about how they feel and perform. As for other shoes, our concern starts and ends with what we’re wearing—not what anyone else will be wearing.”

A final note: The word “banned” is often used in discussions around the WA review of shoe rules. However, the WA cannot universally stop a shoe company from producing and selling a shoe. It can only restrict elite athlete use of the shoe. Who’s an elite athlete? That’s relatively easy to define in the Olympics and World Championships, and relatively more difficult to decide in other events.

Amby Burfoot won the 1968 Boston Marathon. He offers KISS Training Programs (Keep It Simple & Smart) at