Life Science

Incredibly fast and barely legal

Nike’s high-tech racing shoes offer athletes an advantage — but how good is too good?

August 20, 2018
The London Marathon was only one the major races last year where an athlete wearing Nike’s controversial Vaporfly shoes took a spot on the podium. Tirunesh Dibaba of Ethiopia finished second in the women’s field. [photo courtesy of Flickr user Marco Verch | CC BY 2.0]

The sun had already set by the time Camille Herron crossed the finish line at the Tunnel Hill trail race in Vienna, Illinois, last November. Through the darkness, glowing red numbers on the clock overhead announced her record-breaking time: 12 hours, 42 minutes and 39 seconds, more than an hour faster than the women’s prior record for a hundred-mile race. She even beat all the men that day.

“I just felt like I could run forever,” she told me, reflecting on the race.

As an amateur long-distance runner myself, I was enthralled by her athletic feat. In a video recap, Herron stands at the finish line with a smile that beams elation and exhaustion. She looks like a world-class athlete — pure muscle stuck on bone. I barely noticed the shoes she was wearing.

Her shoes aren’t just any old sneakers. They are the shoes of champions: the Nike Vaporfly 4%. In 2017, runners who wore them raked in more than half of marathon medals, including Shalane Flanagan, who came first in that year’s New York City Marathon. Herron was the first to set a world record in them at Tunnel Hill. They’re some of the most comfortable shoes she’s ever run in, she says.

But the Vaporfly shoes offer much more than comfort — they have been proven to help athletes run faster. Runners wearing them race 3 to 4 percent faster than their competitors, according to a recent New York Times analysis that used fitness tracker data collected during marathons and half-marathons over the past four years. These shoes are exceptionally lightweight, shock-absorbent and extra springy, which makes running less energetically demanding. Over the course of a taxing, long-distance race, some sport scientists say their advantage may make a meaningful difference.

But their success begs the question: How can this performance-enhancing equipment be allowed? Innovation and progression in sporting equipment is unavoidable, but at some point, high-tech sports equipment teeters uncomfortably close to unethical.

High-tech gear can reinforce economic inequalities: Top-notch equipment is expensive, and runners who can’t afford to buy it may not be able to keep up in competition. It’s also akin to doping — aren’t performance-enhancing drugs technologies too, albeit pharmaceutical ones? “We normally think of performance enhancement and trying to police it and control it as doing drug testing — peeing in a cup, finding needles for blood doping — but we forget that technology is a performance enhancer, too,” Arthur Caplan, a medical ethicist from NYU Langone Medical Center, told WGBH in a 2017 interview.

Since the start, the Vaporfly shoes have been controversial. They were made famous when Eliud Kipchoge ran in a prototype version earlier in 2017 during Nike’s attempt to break the two-hour marathon — a near impossible record in the sport. The company designed an elite, customized version of the shoes specifically to help their athletes (Kipchoge and two other world-class runners) race against the clock. They then released the shoes to the public in March of 2017, two months before the momentous race. Critics argued that whole attempt was a publicity stunt; that Nike just wanted to sell more sneakers. Whatever their intent, Nike certainly caught the running community’s attention. Athletes, coaches and sport scientists have been talking about these high-tech shoes ever since, wondering if they should be allowed.

“This is a game changer,” George Hirsch, the chairman of the New York Road Runners, an organization that hosts races and running events in New York City, told the New York Times. Plenty of runners now race in Vaporfly sneakers. The International Association of Athletics Federations (the sport’s governing body) has never found the shoes to break any rules. In their design and their potential speed-giving advantage, they’re perfectly legal.

The Vaporfly shoes represent a natural progression in running shoe technology, according to Wouter Hoogkamer, a sports physiologist at University of Colorado. Last year, he teamed up with Nike to study these shoes in the lab. Their study, published in Sports Medicine, found that the Vaporfly shoes improved running economy by 4 percent on average — that’s where they get their name. Essentially, it means that athletes burn 4 percent less energy running at any given speed.

The shoes have a thick sole made of flexible, lightweight foam with an embedded carbon-fiber plate, Hoogkamer says. Those attributes seem to act in combination to help propel a runner forward while also reducing a runner’s energetic demands, and the impact through their legs as their feet pound the pavement. However, researchers still don’t know specifically what it is about the shoes that causes the 4 percent advantage.

The cause is likely a combination of many small changes that add up to the 4 percent difference, Hoogkamer says. He and his colleagues are now working to find out which biomechanical factors are the most influential in improving running economy, and how the change in efficiency translates into speed. “We don’t know that if you use 4 percent less energy, you run 4 percent faster,” he says. The resulting improvement in speed is likely a bit smaller.

4 percent may not sound like much, but it can make a big difference. To put things into perspective: “If you were to add a pound of mass to each of your shoes, that would basically make running 4 percent harder,” Hoogkamer says. Compare that to an illegal drug like erythropoietin, which improves running performance by about 6 percent, and you suddenly have a better understanding of why these shoes have triggered so much debate in the running community.

Hoogkamer doesn’t think the Vaporfly shoes are unfair. Technological advancement is inherent to sporting equipment, he says. Before the Nike’s Vaporfly model, Adidas had a shoe that gave runners a 2 percent boost in running economy. Before that, we had older, less efficient running shoes. And before that, we were running barefoot — the least energetically efficient of all. “Should we all go back to running without shoes?” he asks. “Where do you draw the line?”

I remember the running shoes my mom had when I was a kid — tattered blue-and-white sneakers with rock hard soles. It’s amazing how far shoe technology has come even during my lifetime. Your standard running shoe is now an impressive piece of engineering.

Even the Vaporfly is commercially available. Any athlete who wants to run in these high-tech shoes can go out and buy a pair, Hoogkamer says. I took his word for it and went to the nearest Nike Store. When I asked the woman who worked in the shop if they had any I could try on, she shook her head. “We used to,” she said. They’re nearly always sold out.

The Vaporfly is a hard shoe to find, which is a bit surprising considering its price. The commercially available model goes for $250 — almost twice the price of your standard running shoe, according to Erison Hurtault, head coach of New York University’s men’s cross-country team. “That’s starting to push it for what people budget,” he says.

The price may be limiting for some people, says Hurtault. Some of his athletes train in the Vaporfly shoes, although he says he doesn’t notice a difference in their running times. That’s not to say that the shoes only work on elites. But at non-elite levels, there are a lot of other factors that can affect an athlete’s success, like better physical training or finely-tuned nutrition. There are other things that athletes should be spending their time and money on, he says.

In amateur sport, the Vaporfly shoes may not be a ticket to the podium. But what’s potentially disturbing is what the shoes represent for the sport’s future. For me, running has always been about inclusiveness and simplicity – personally, I got into running as a college student because it was free. It’s not a gear-centered sport. What I fear for the future is that people who can’t afford to buy the right equipment, be it shoes or something else, literally won’t be able to keep up with the rest of the pack.

As I left the Nike store, a wall of television screens publicized the latest shoe and flashed the iconic Nike swoosh. I walked away wondering what kind of sports’ technology Nike might experiment with next.

High-tech sports equipment is one thing, but performance-enhancing drugs are also encompassed by this new technological wave, according to Mark Johnson, author of Spitting in the Soup, a book about the history of doping. In the next few years, “doping” might even include genetic engineering, he says. “They all fall under the umbrella of sports enhancing technology,” he tells me. They all help an athlete perform the best that they possibly can.

Technology and doping have always been a part of professional sport, Johnson says. It’s our moral judgements that change. Up until the 1960s, athletes openly used performance-enhancing drugs and the public was largely unfazed. Fans saw professional athletes a bit like we see rock stars today. “We don’t really hold a grudge or say that Keith Richards is a bad person because he’s taken a lot of drugs in his life,” he says. We just enjoy the show.

Drugs have been demonized more than equipment today, according to Johnson. But whatever the tech, what we’re chasing is just an exciting exploit. “We’re watching pro sports because we want to see the best performance in the world,” he says. Professional sports are about entertainment and making money, not about making the world a better place, he says. Amateur sports can teach good values, like discipline and teamwork, but professional sports are “an amoral quest,” he says.

I hung up the phone feeling drained and, to be honest, a bit bummed out. Johnson’s explanation makes sense, but it’s brutally cynical. I wanted to believe that the athletes I looked up to — Kipchoge, Flanagan and Herron — were better role models than Keith Richards. Surely, I thought, there is more to elite sport than pure performance.

If sport was only based on performance, it wouldn’t be all that interesting, according to Thomas Murray, a bioethicist who headed the Hastings Center until 2012 and the author of Good Sport, a book about the ethics of sport-based doping. It would be too simple; the sport would be too easy. When we watch professional athletes, we want more than amazing performances; we want to witness innate athletic talent, finely tuned skill and the product of hard work.

The idea that high-tech equipment might compromise these values is not a new one, Murray says. We’ve seen it in everything from golf to speed skating to pole vaulting. Whether the sport decides to accept or reject the technology, he believes, depends on whether or not the advance threatens the true meaning of the sport.

“Take swimming for example,” Murray says. At the 2009 world championships in Rome, swimmers wore extra-slick, full-body suits. They crushed 46 world records that year. The swimsuits helped with buoyancy, making athletes float closer to the surface of the water, where they experienced less drag.

The suits made winning too easy. And in the process, they changed what it meant to be a champion swimmer. With the suits, swimming was “rewarding muscled, stocky athletes who paddled on top of the water rather than sleek bodies slicing through it,” Murray writes in Good Sport. In 2010, FINA (swimming’s governing body) banned the high-tech suits. They would have altered the sport and what its athletes value.

In the sport of long-distance running, I have yet to meet an athlete who doesn’t value hard work. And Herron is no exception. When I asked her how much she trains, she said she has run over 100 miles per week every week for the past 11 years — numbers perhaps more meaningful than Nike’s 4 percent.

“Behind every great shoe is a great runner,” she says. Call me naïve, but I think I believe her.

*Correction, August 20, 2018: The following errors have been corrected from the originally published version of this story:

The original version of this article misquoted Johnson saying that professional sports are an “immoral quest.” He says they are an “amoral quest.” 

*Correction, August 21, 2018: The following errors have been corrected from the originally published version of this story:

The original version of this article stated that Herron broke the men’s and women’s prior world record for a hundred-mile race. She broke the women’s world record.

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3 Comments

Ski says:

Hard work is the key for any athlete.100 mile weeks for 11 years in the main factor in success

Lisa says:

This is so inspiring!

Dinke says:

100 mile weeks will break your bones. Just sayin.

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