The Most Controversial Running Shoe Nike Ever Designed

World Athletics zeroed in on the Nike Vaporfly and Alphafly — why?

Nike Air Zoom Alphafly NEXT%, evolution of the Zoom Vaporfly NEXT%.

These running shoes are making everybody fast — like really fast.

Nike recently had the Breaking2 project come to its climax on May 6, 2017. On that day, Eliud Kipchoge would come 26 seconds too slow to break 2 hours for the marathon.

Kipchoge’s personal best before that day was 2 hours, 2 minutes, and 57 seconds set at the Berlin Marathon in 2014. Just two years later, one year before the Nike project, Kipchoge ran 2 hours, 3 minutes, and 5 seconds at the London Marathon in 2016.

By 2017, that number fell to 2 hours and 25 seconds. Kipchoge improved the world record, unofficially, by 2 minutes and 22 seconds. To put that into perspective, Kipchoge ran 4 minutes and 42 seconds per mile for 26.2 miles at Berlin.

He improved that time to 4 minutes and 36 seconds per mile. The world record in a single mile was set by Hicham El Guerrouj in 1999. That time was 3:43.13. Less than a minute separates these two marks, with the one caveat that Kipchoge repeatedly runs this non-stop for the length of an entire marathon. That’s a little over 26 consecutive times.

On the Breaking2 race day, Kipchoge had the benefit of 30 pace-makers, a pace car, and a nutrition team on-call during the length of the marathon. Just with these, the results of the race wouldn’t qualify as a world record. But the most important thing wasn’t any of the above. It was the shoes he was wearing: The Zoom Vaporfly prototype. The shoe had a carbon fiber plate to help propel athletes forward. Independent testing said that it improved energy efficiency by about 4%. In other words, you were 4% faster for wearing a special shoe.

The evolution of this shoe would not stop here. Several athletes would mark significant improvements in short spans of time:

  • Zersenay Tadese also completed the Breaking2 attempt. Tadese set a new personal best by more than four minutes. He finished in 2:06:51.
  • Japan’s Mariko Yugeta became the first woman aged 60 or over to break three hours when she ran 2:59:15. This is more than 3 minutes better than the previous best set over 13 years ago.
  • Uganda’s Joshua Cheptegei broke the 10-year-old 10km road world record in Valencia by six seconds in 2019. That record lasted six weeks — 20-year-old Kenyan Rhonex Kipruto dropped it further by 14 seconds. Cheptegei now also holds the world record in the 5,000 meters, a record set previously by Kenenisa Bekele 16 years ago. Cheptegei bested that time by 2 seconds, down to 12:35.36.
  • Sifan Hassan took double gold at the World Championships in Doha in September. She won both the 1,500m and 10,000m in a track spike version of the Vaporfly.
  • Brigid Kosgei beat Paula Radcliffe’s world marathon record in October in the newest evolution of the shoes, reducing the mark by 81 seconds down to 2 hours, 14 minutes, and 4 seconds.

Almost every notable achievement and world record in the last 4 years has been done with the help of the Vaporfly (or some version of it).

This prompted World Athletics in January of 2020 to make some new rules. Notably, after April 30, no prototype shoes would be allowed. Furthermore, any shoe with a sole thicker than 40mm of shoes that contain more than one plate would also not be allowed.

In Vienna on October 12, 2019, Eliud Kipchoge shocked the world again by besting his Breaking2 time down to 1 hour, 59 minutes, and 40 seconds. This feat, while inhuman and earth-shattering, would later not be recognized as the world record. This is because the shoe, a prototype of the Vaporfly (called the Alphafly), would have a sole thicker than 40mm. While the Vaporfly NEXT% falls within the rulebook and avoids a ban, the Alphafly prototype does not.

These rules are a reasonable framing of a rapidly progressing technology. The gaps that the world records are dropping by are some of the largest in the last few decades. Kipchoge ran 2 hours, 1 minute, and 39 seconds at the Berlin Marathon in 2018. That was 78 seconds faster than the previous world record, set by him. It is the largest jump in world record improvement in 50 years.

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World record marathon progression 1905-present.

And it’s not just making people faster. It’s stirring trouble with sponsors, too. Specifically, the runners who have sponsors that are anything other than Nike. At this point, it’s pretty well-known that the Vaporflys will add a spring to your step, for free. This has meant that runners sponsored by other brands have been blacking them out to run with them in secret. If they don’t, they risk running at a disadvantage

Source: Aylin Woodward, tweet about the trend of blacked-out Vaporflys.

The answers going forward are not very easy. On the one hand, it’s a shoe, and Nike is allowed to research and develop. On the other hand, their technology is clearly giving runners an edge. If two runners of identical strength run a marathon, the one with the shoes will win. Always.

The World Athletics imposed the following rules:

  • Sole thickness of shoe cannot exceed 40 millimeters.
  • Shoe cannot contain more than one plate.
  • Shoe must be available on retail market for longer than four months before being used in competition. This is basically known as the “no prototype use”.

At the 2020 Women’s Olympic Marathon Trials, Kara Goucher said, “I do feel like it wasn’t a level playing field. I felt like something I had worked so hard for had been stolen from me. I could handle not being good enough to make our team, but learning that a propulsion device in a shoe might have kept me out was just devastating.”

She was using a Sketchers running shoe(her sponsor since 2014).

For now, it seems like the World Athletics is on the right track. Geoffrey Burns, a biomechanist at the University of Michigan, suggested that the “stack height of a shoe’s heel should be limited to 31mm — the height Nike initially listed for the Vaporfly, though tests later showed it to be 5–6mm thicker.”

He expands on that idea:

“The motivation was to write some sort of very simple regulation that’s relatively future-proof. A very simple way of doing that is to limit the height. Operationally, it’s super-easy to enforce. With height restrictions, the more you limit that sole’s real estate, the more other things you put in there don’t matter or can’t make a significant difference. If you have a reasonable height restriction, you couldn’t advantageously fit in two plates. The benefit of a plate is only afforded by a thicker and thicker shoe.”

In the past, the World Athletics has taken heavy criticism for not acting on technological advancements. In this case, it seems that they are acting in favor of keeping the sport as close to its original roots as possible. And that’s a good thing — because, if the technology continued to gallop the way it was, it could significantly ruin many of the records that took a lifetime to accomplish.

One thing is clear: Nike has thrown a serious curveball in the game. And everyone wants a piece of it.

Written by

UC Berkeley, mathematics. Los Angeles. Long-time runner. Top writer on Quora, 100M+ total content views. New to Medium. Inquiries:

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