Today, even with the Olympics and other major athletic events postponed to prevent the spread of the coronavirus, the sport of running remains upside down, with the focus still on shoes instead of on who’s wearing them.
Today, even with the Olympics and other major athletic events postponed to prevent the spread of the coronavirus, the sport of running remains upside down, with the focus still on shoes instead of on who’s wearing them. (Photo: Courtesy Nike)

Is the Battle Over Nike’s Vaporfly Ruining Running?

Today, even with the Olympics and other major athletic events postponed to prevent the spread of the coronavirus, the sport of running remains upside down, with the focus still on shoes instead of on who’s wearing them.

Over the past few years, the sport of running has been upended by a debate over shoe technology. It all began in early 2017, when Nike announced a prototype called the Vaporfly that was billed as improving a runner’s efficiency by 4 percent—a claim that was hard to believe until that spring, when Kenyan Eliud Kipchoge came seconds away completing a marathon in under two hours. The running community’s reaction was swift, with many claiming that the shoe wasn’t a breakthrough, it was a cheat. A lot has changed since then, with records at numerous distances being obliterated while other shoe brands look to duplicate the Vaporfly’s success, even as they call for new Nike prototypes to be banned. Today, even with the Olympics and other major athletic events postponed to prevent the spread of the coronavirus, the sport of running remains upside down, with the focus still on shoes instead of on who’s wearing them. Outside editor Chris Keyes speaks with our Sweat Science columnist, Alex Hutchinson, about how we got here and what it all means for the future of the sport.

Podcast Transcript

Editor’s Note: Transcriptions of episodes of the Outside Podcast are created with a mix of speech recognition software and human transcribers, and may contain some grammatical errors or slight deviations from the audio.




Outside Podcast Theme: From Outside Magazine and PRX, this is the Outside Podcast.

Michael Roberts (host): It seems kinda strange right now, but not that long ago, people were very fired up about sports. And in the world of elite running, they were particularly fired about shoes.

At the end of February, the world was still planning for the summer Olympics, in Tokyo, and the United States held its Olympic Marathon Trials in Atlanta. The dominant topic that day was which pair of shoes the top athletes were going to wear.

Even if you don’t follow running, chances are you know this is all because of the Vaporfly, a shoe created by Nike that has completely upended the sport.

A brief history of how that happened, goes something like this:

In early 2017, Nike announced a prototype running shoe that had a carbon fiber plate inside a  super thick and super springy midsole. Called the Vaporfly, it was the cornerstone of a much-hyped bid to have a runner do what was still considered impossible: complete a marathon in under two hours. The Vaporfly was billed as improving a runner’s efficiency by 4 percent, a claim that was hard for serious runners and coaches to believe.

Then, in May 2017, Kenyan runner Eliud Kipchoge nearly pulled it off. Wearing the Vaporfly on a race track in Italy, he finished a marathon in 2 hours and 25 seconds. It was short of Nike’s goal, but more than two minutes faster than the world record. As many people saw it, the Vaporfly wasn’t a breakthrough, it was cheat, a form of mechanical doping that gave a runner an unfair advantage.

Over the last few years, a lot has changed. Running records at numerous distances have been obliterated. There’s been an arms race among shoe makers looking to duplicate Nike’s success, even as they still call for new editions of the Vaporfly to be banned.

Today, even with the Olympics and other major athletic events postponed to prevent the spread of the coronavirus, the sport of running remains upside down, with the focus still on shoes instead of on who’s wearing them.

A couple weeks after the February U.S. Olympic trials, Outside editor Chris Keyes called on Alex Hutchinson, who writes the Sweat Science column for Outside Online, to talk about how exactly we got here and what it means for the future of the sport. Alex knows all this as well as anybody: He’d been invited to Nike’s headquarters for a sneak preview of the Vaporfly a few months before the unveiling, and he’s been reporting on what it’s meant ever since.

Here’s Chris.

Chris Keyes: Did you know what you were going there for? What did you know when you flew to their campus?

Alex Hutchinson: All I knew was that they were about to unveil a big project, which became known as the Breaking Two Project, where they were going to enable runners to run a sub two hour marathon. At least that was the goal. So it was a ludicrous goal because, you know, the world record was 2:02:57. So we knew they had to have something up their sleeve, but we didn't know what. It was me and one other reporter, Ed Caesar from Wired Magazine and about 10,000 senior Nike executives and media relations people in the top secret Nike headquarters.

We were there for about three days, and we saw a lot of things, and they had a lot of wheels and moving parts that were going to try and help them get to the two hours. But we were sort of waiting for the other shoe to drop, so to speak -- it had to be something big, it wasn't just going to be they were going to have a more aerodynamic pair of shorts or whatever. So eventually they got around to telling us that, one element of this big grand plan is well, we have a new shoe. They took us through some history. They showed us, I think it was Allyson Felix’s spike plate from the 2012 Olympics, which had been a custom made curved carbon fiber spike plate. And they'd said they'd been playing around with that technology and they had this new model for a shoe that they thought was going to be pretty special.

Keyes: Where are you at this point? Are you like in a conference room and they have this shoe in front of you, or have they not even revealed it yet?

Hutchinson: Day one, when they first presented this concept to us, we didn't see a shoe at all. They just showed us the plate. And Allyson Felix has played, and that was in a conference room somewhere in Nike Headquarters. The next day, with a whole bunch of fanfare, we got invited inside the Nike Sports Research lab, which from what we understood, not only do journalists never get to go, only something like 1% of Nike employees have the right to go -- it was like going into an airport except it was like going into Tel Aviv airport or something like that.

It was a very special situation and we got to go in and actually see -- we met some of the athletes who were part of the Breaking Two Project including Eliud Kipchoge. They were there to do some testing and we were going to watch them do their testing and one of the things they were going to do was test out this new shoe. Each of them were testing out three versions of the shoe with different stiffnesses of the carbon fiber plate to figure out which one was best for them. But they let us try it on, and jog a little bit. And it felt different. As soon as you pulled it on, you knew there was something.

Keyes: What did it feel like?

Hutchinson: It felt like you couldn't stand straight up in it. It felt like you had to lean forward in it, or like you had to be like standing on a steep uphill in order to lean to stand straight up, if that makes sense. So you could feel that there was something in the shoe that was not parallel to the ground. And the power of suggestion is pretty powerful, but it felt like it wanted you to spring into motion and start running. It really felt like it was pushing you forward

Keyes: This was the Vaporfly, or at least as close as they got to it at that point, what would be the Vaporfly shoe, is that right?

Hutchinson: Yeah, I think you could call it the Vaporfly. It was the Vaporfly in all, but the styling, cause the way it has come to market is it has a very different and distinctive look. But that's a styling decision. It doesn't have to look that way. It could look just like an ordinary shoe, and that's what we were experiencing on that day in late 2016

Keyes: It didn’t seem like they weren't making a huge deal, at least with you guys while you were present. But were they making the claim then, as they do now, that the shoe would boost your performance by up to 4%?

Hutchinson: Yeah. They told us right from the first, they told us this 4% statistic -- they were also making other claims of a similar magnitude. For instance, that the effect of drafting in a well optimized pack would be comparable. So they were making big claims, but in the context of many big claims, and they did say that this 4% figure had been tested in an external lab, which I later found out was, was Roger Kranz Laboratory at the University of Colorado, which is a very well respected lab.

So I was sort of two minds after that first day or those first two days, which was -- I knew that they wouldn't spend what I was estimating was going to be tens of millions of dollars on this Breaking Two Project if they didn't think they had a legitimate chance of doing it. And of all the stuff they presented, I think it was five pillars of innovation, nutrition and pacing and all these different things. And I listened to them all and I'm pretty familiar with what's at the cutting edge and the only one that struck me as being really significant -- or the two that struck me as being potentially significant were drafting and the shoe, so I knew they had to believe in the shoe. At the same time, we've heard hype from shoe companies on an annual basis, since before I was born. On its own, the fact that they said it's gonna make you 4% more efficient, didn't necessarily convince me, but the fact that they were willing to back it up by saying, we're going to bet it all on getting someone close to a two hour marathon made me think, hang on the shoe might be for real.

Keyes: Let's move forward a little bit. When did you start to see the kind of results athletes were having in issues that basically confirmed this boost -- the magic nature of these shoes?

Hutchinson: You could argue that in May of 2017 when Eliud Kipchoge ran 02:00:25. That was the first real hint. That's when the shoes made their debut. But it was under artificial conditions. And he had pacemakers and there was a pace car in front of him that some people thought was blocking the wind, so there were alternate explanations

Keyes: This is the initial under two attempt, right?

Hutchinson: Yeah. The first breaking two race or the Breaking Two Race. And this was in 2017. So it wasn't a world record, but it was two and a half minutes faster than the world record. And one possibility was that this was the shoe that worked, but we didn't know how much was the shoe and how much was the other factors. So we were sort of waiting to see what happens in a real marathon.

And so that fall, Berlin is the place where people run fast. Um. And Eliud Kipchoge went there and he ran fast, but it was pouring rain that day, and so I can't remember exactly what his time was, it was maybe about two or three or something, so he didn't break the world record. So it was like, well, he was fast, but it's not nothing that hasn't been done before.

And then the next fast marathon was London in the spring of 2018 and it was the hottest London marathon in history actually. And so again, Kipchoge and some of the other guys ran very fast, but nothing that hadn't been done before. So it wasn't until it was fall of 2018, September of 2018, when Kipchogee broke the world record, the official world record. He ran 02:01:39. And he didn't have all the other Breaking Two pace car kinds of things. And so then it was like, wow. Either the shoes or something super, super, super special. Or Eliud Kipchoge is superhuman, and I would say -- so that takes us to the end of 2018, then in 2019 it was like it was undeniable. All of a sudden, a bunch of people that most devoted fans of the sport hadn't even heard of, started throwing down fast times on both the men's and women's side, and so through 2019 it was really building to then -- by the end of 2019 when the women's world record was shattered and Eliud Kipchoge in the Ineos race ran sub two and the men's and women's half marathon and 10K world records went down. It just seemed national records by the dozens were going down. So it was a slow burn. There was no one moment until, I think it was by the end of 2019, it was like the last skeptics were like, okay, okay,I admit, these shoes are really, really fast.

Keyes: From that period between 2016, when you first learned about this, and 2019, where you kind of make your own confirmation and everybody else does, that, yeah, I guess this shoe works -- were people starting to make claims that this was cheating or complained about these shoes?

Hutchinson: Yes. I mean, I think the debate and the complaints that it was cheating started before people even knew what the shoe was. They started more or less as soon as Nike announced that they were gonna have this Breaking Two Project to try and break the two hour marathon. At first, they didn't announce how they were going to do it, so there was lots of speculation and as soon as they put out the press release said, Oh, by the way, we have this new pair of shoes that's pretty fancy. People said, well, that's it. They're cheating. Whatever they're doing, it doesn't matter what it is, we don't even know what's in the shoe, but it has to be cheating. If it's going to enable someone to go under two hours, then it must be cheating. And once they knew what it was, they said, okay, well then it's the carbon fiber plates, it’s the cheat. But I think that the assumption that was cheating started right away and was sort of based on the magnitude of the claim more than the specifics of what was in the shoe.

Keyes: At this time, as people are starting to make the cheating claims and these records are being broken, during that time, the IAAF or what's now the governing body, they didn't make any changes to their rules. Did they make any announcements about the shoe?

Hutchinson: They made one change to their rules, which was that any shoe used had to be reasonably available to all in the spirit of the universality of athletics.

Keyes: Translate that.

Hutchinson: What I read that to mean was that you couldn't use prototypes anymore, which I think doesn't ban the carbon fiber plate shoes, but it avoids the situation like you had at the 2016 Olympics, and, for that matter, at the 2016 U.S. marathon trials, where you have a few runners who have shoes that are probably a couple of minutes better than anyone else's shoes and nobody even knows about. And that I think we can all agree that's not a desirable scenario. Whether it's illegal or cheating is another question, but it's not desirable. You don't want to have a small group of runners having a weapon like that. And so I read this rule to mean that the prototype era was over. You had to just race in stock shoes. Nobody else seems to, at least nobody in the elite sports world, seems to have read that way because athletes, not just from Nike, again, from all the companies, continued to wear prototypes and races and nobody did anything about it.

Keyes: The governing body did not enforce that rule.

Hutchinson: The governing body did nothing. There were no sanctions. The rumors I heard from someone who heard someone who was on the committee saying, Oh yeah, we didn't intend it to ban prototypes. It was j you couldn't bring a new type of shoe onto the market, which I don't even know what that means.

It was a toothless rule, and it served to almost sort of emphasize the toothlessness of what world athletics were doing -- they were producing rules that were essentially meaningless, and then not even enforcing the meaningless rules.

Keyes: So now we know the shoe is effective, clearly. As you said in the 2016 Olympic trials, you called the shoe two to three minutes faster, which is enormous. So what is it about the shoe? You mentioned carbon plates. What do we know about what's inside? And do we know why it works or are we still like cram saying, we know the shoe works, but we don't have any idea why.

Hutchinson: There's three basic parts to the shoe, or at least to this type of shoe. One is this stiff carbon fiber plate that's embedded in the midsole. And the midsole itself is a very thick midsole. So it's not quite platform shoes, but we're talking in the neighborhood of, let's say, an inch to an inch and a half. So it doesn't look like your typical racing shoe. That thick mid-sole is significant because when we talk about spring loaded shoes, people are thinking about the carbon fiber plate, but in fact, every shoe has a spring and that is the midsole of the shoe. And you have this foam midsole. When you land, it gets compressed. And when you take off, it springs back and kind of pushes you forward and saves you some energy. And the thicker that the midsole, you can have, the more energy, it's like having a bigger battery. You can store more energy with each stride and give more back to yourself. So that's one of the big factors that helps efficiency.

And the third factor, so you've got the carbon fiber plate, the thick midsole, what allows this to be built without making it totally clunky is that you've got a new foam in the midsole, a foam that is lighter than any foam that's ever been used in a shoe before, which means you can have a thick foam without feeling like you're wearing bricks on your feet, and it's also more resilient, which means that when you land on it and it springs back, it gives you more energy. Typical shoes are made or have been made with EVA, which gives you about 65% of the energy. It gives you back about 65% of the energy you put in. About six or seven years ago, Adidas came out with a foam called Boost, which was at the time, the best foam ever. It was light and it gave you back about 75% of the energy you put in. So 10% better. And Nike's Vaporfly came out with a foam they called Zoom Max, which is another 10% better.

So it was giving you a back about 85% of the energy you put in. So you've got this big thick layer of light and resilient foam. If you just try and run on a huge stack of ultra light foam, it's going to be very unstable. But the carbon fiber plate gives you some stability and keeps your foot in a position that reduces the amount of energy you're wasting.

So there's a lot of debate about exactly how these things work together and how much the plate makes a difference versus the foam, whether the plate is saving energy by keeping your big toe from bending and things like that. I think my reading is that the most significant thing is that it’s enabling you to take advantage of this big stack of thick, lightweight foam.

Keyes: As you say, none of those individual pieces of the shoe, including even the carbon plate are necessarily new. We've seen all of these things in a shoe before, if not the exact foam that Nike is using, that's what every company has been trying to do is make a lighter and more effective foam, but none of these individual pieces are brand new.

Hutchinson: Yeah, and I think that's a really important point, because there is the perception that, oh my god, they put a carbon fiber plate in the shoe, the humanity, how could they dare do this? Well, a friend of mine recently dug up some old Brooks ads from the early nineties cause Brooks introduced a full length carbon fiber plate that they called it the Propel, back in 1989 is when they introduced it. They had two shoes called the Fusion and the Vision with carbon fiber plates. Fila in the 1990s had a carbon fiber plate Paul Tergat the world marathon record holder ran in. Adidas is the one who got closest to what Nike did.  They had a curved carbon fiber plate that they called the pro plate. And by some accounts, at least, Haley Gabra Selassie set a marathon world record in a shoe with the pro plate in it.

So you can see that there's a genealogy of where these things come from -- that carbon fiber plate didn't come out of nowhere. And the Boost foam was better than what had come before that. And Zoom X was a little better than Boost. And now all the other companies are playing around with different foams trying to find the latest and most resilient. But somehow, and I think credit is due that the designers at Nike found a combination -- found that just the right, the angle, the thickness and everything,r hat wasn't 1% better or 2% better, because there'd been lots of examples of claims of 1% or 2% before. In fact, the Adidas carbon fiber plate, there's peer reviewed literature that was published in journals saying that it makes you 1% faster. No one cared. This was q5 years ago. Nobody cared that this carbon fiber plate made you 1% more efficient -- but Nike got it in a way that it was 4% and all of a sudden you can't ignore 4%.That's, that's too big to ignore.

Keyes: Put that in perspective for us. We've been talking about cheating and people claiming that this is cheating. So how does 4% compared to actual cheating using, let's say EPO?

Hutchinson: I have a great comparison at the tip of my fingers, cause I just read a study that analyzed the results of Russian women's distance runners from 2009 to 2017, and basically what they were looking at is what happened when they introduced the biological passport, which is a new method of blood doping that makes it much harder to blood dope. What they found is on average, the Russian women, as soon as in 2012, when sanctions started to be applied with the  biological passport -- across the board, Russian women's middle distance runners got about two to 3% slower, with a range of about one to 4% slower.

And so what the lead author of that study told me is that, I take that as an estimate that plugged doping gives you, on average, about two to 3% gain in your race times. Now, when we talk about the shoes, we're talking, let's say 4%, although the latest iterations of the shoes I've heard are more like 6% or 7% to 8%, so it may be even bigger than that, but even if you just stick to 4%, that’s in efficiency, so you burn 4% less energy. That, by some calculations for an elite marathoner, should make you about two and a half percent faster. So almost identical to what you're apparently getting from blood doping prior to the institution of the biological passport.

Keyes: So this is significant.

Hutchinson: Um. Yeah, it's a race winner. Obviously you can't go from last to first -- I'm not going to go win a marathon if I put on shoes like this, but in a competition among equals, the person with the 4% better shoe is going to win 99% of the time.

Keyes: Can you win without the Nikes right now?

Hutchinson: You can. And we don't have to look far for that. The U.S. Olympic marathon trials a week ago. On the men's side, I think it was 9 of the top 10 finishers were wearing a version of the Nike Vaporfly. But on the women's side, the picture was quite different. The winner was, if I'm remembering correctly, was wearing a HOKA shoe with a carbon fiber plate, but it was a HOKA shoe, and only one of the top. the third place finisher, Sally Kipyego, was wearing a Nike Vaporfly model, but most of the top finishers on the women's side weren't.

And that isn't because the Nike shoes don't work for women or anything like that. It's just a couple of things. One, it’s just a question of which top runners happened to be sponsored by which companies? It's also a function of other companies introducing shoes that are -- everyone had a shoe with, or almost everyone had a shoe with some sort of carbon fiber plate and foam in it. So it's no longer 4% versus 0% it's 4% versus we don't know, 2%, 3%, 4% -- no one has released the data, but the other companies have closed the gap

Roberts: We’ll be right back


Roberts: At the 2019 Chicago Marathon, the top ten finishers in the men’s race all wore Vaporflys. It was starting to feel like for runners to even hope to be competitive, they would have no choice but to tie on a pair of the shoes.

Except, there was already a newer, faster model. Just the day before Chicago, Eliud Kipchoge achieved the impossible, running a marathon distance in 1 hour, 59 minutes, and 40 seconds. He was wearing another Nike prototype, this one dubbed the Alphafly, which rumors have suggested gives runners as much as an 8% improvement in efficiency.

For many runners--Alex Hutchinson included—the intense focus on shoe technology, and away from athleticism, is a problem.

Keyes: So you mentioned the Alphafly, which was Nike's newest version of this technology. But as you have written, when this debuted at the second Breaking Two attempt, which was a success, this thing doesn't look anything like the Vaporfly. I think you called it a ‘moon boot.’

Hutchinson: Yeah, I'll confess that everyone reaches their breaking point at different moments. And for me, this was last October, in the middle of the night, watching Eliud Kipchoge run toward a sub two hour marathon distance exhibition race. Exciting moment, but for me, it was stuck in my craw a little bit because I looked at the shoes and I was like, yeah, okay, that's a bridge too far. They have these bizarre pods in them and they don't look like platform shoes, they look like platform shoes on top of platform shoes.That’s the straw that broke the camel's back, especially if the rumors are true, that they're roughly twice as good, they're giving you 7% to 8% instead of just 4% compared to what shoes used to give us.

Now as it turns out, it may be that I'm reacting more to the styling, than to the substance, because apparently they're actually not all that much taller than the previous version. The Next%, they're just styled in a very different way that makes them look more bizarre. And so I shouldn't get too upset about the style as opposed to the substance. But I have to admit that I looked at them and I thought, this cannot be where we're headed in this sport, you know?

Keyes: Well, and I think even if you are wrong and what's inside the shoe isn't fundamentally that different, you're getting at a point here, you're a big running fan and suddenly these performances are starting to rub you the wrong way. Like maybe this isn't the way the sports should be going and it's too reliant on the technology and actually the run itself.

Hutchinson: Yeah, and I think there's been people who've been saying that obviously since the day the Vaporfly was announced. And I understood that, but I was always --I tended to err on the side of, you know what, it's maybe not what I would choose, I would like us to all be very purist and traditionalist, but I don't see any rationale for standing in the way of what may be a pretty cool shoe that has benefits, not just for athletes, but for the rest of us.

I think the part that beyond the styling element -- my sense was that Nike dropped the bomb on the world with its Vaporfly. There was some carnage, there were some races won that maybe shouldn't have been won, like at the 2016 Olympics. Then we started to pick up the pieces. All the other companies realized, okay, this is a real thing. It doesn't look like there's going to be any rules. Let's start working on our own versions. We were approaching a moment where it felt like parody was coming back. It's never a perfectly level playing field that doesn't exist. But it was going to be a case where we're getting back to the point where you don't stand on the starting line and say, well that dude's not going to win because he doesn't have the latest shoe.

And then all of a sudden, just when I thought we were at that point, the Alphafly comes along and now we're back to square one where even the people, if they had the original Vaporfly or these competing ones, well they don't have a chance cause they don't have the latest shoe. So, and if that happens, then my fear became maybe the same thing's going to happen next year and the year after and we're going to be in the age of endless shoe wars where who your shoe sponsor is becomes the Formula One model as opposed to the NASCAR model where it's an equipment maker’s and it's an engineer's challenge as well as a runner’s challenge.

Keyes: Which is exactly when you should have a governing body step in. And in the winter they do step in. Last, either January or early February, they announced some new rules. Did it change anything?

Hutchinson: That remains to be seen. They announced these rules -- after the Alphafly was introduced last fall in this exhibition race, there was a lot of talk, including a proposal in the British Journal of Sports Medicine saying, alright, we need to get something. What's the simplest way to regulate it? Banning carbon fiber plates is sort of missing the point. Why don't we just limit the thickness of shoe midsoles? Why don't we say the shoe can only be X high. And I thought that was a great idea. And I wrote about that a little bit.

And the question was how high do you make the limit?And it's hard to get reliable numbers on how high these shoes are. I mean there were all sorts of differing ideas. And one number that was suggested was 31 millimeters, cause that was the original Vaporfly. Another one was 35 millimeters cause that was how high. HOKA’s biggest shoe was, which was the thickest shoe on the market before the Vaporfly. And then there was, well, maybe we should make it 36 or 37 or even 38 millimeters, because that's reportedly what the next percent, which was the second version of the Vaporfly was, and a bunch of people that are already set world records in the next percent. So in order to avoid this sort of awkward situation of, oops, they set a world record in an illegal shoe, let's make it 38.

So then the rule came down and sure enough, it was a limit on height. But it was 40 millimeters. Now, two millimeters doesn't seem like a big difference. You say, well, 38, 40 millimeters, whatever they did the job, at least we're not gonna see the Alphafly, that abomination, showing up in competition. Then four days later, four or five days later, Nike announces, here's our Vaporfly. Oh, and by the way, guess what the stack height is for the men's size, eight and a half, which is the reference size on which the measurements are made. The stack height is 39.5 millimeters. So it comes in under 40 millimeters.

And so there were a lot of people, including me, who woke up that morning thinking, wow, we live in a world of amazing coincidences. What a fantastic stroke of luck for Nike. So the Alphafly is legal for this summer Olympics. Maybe that's enough. Maybe the Alphafly’s where it stops and we can all learn to live with that as time goes on. Or maybe there'll be more innovation within that 40 millimeter window  -- I guess I certainly wish it had been, it had been a little bit tighter, down at sort of the 36 millimeter mark or something like that. But it's hard to know whether any of those 40 millimeters make a difference or whether, as some people argue, one was going to go to 50 millimeters anyway, and, just for context, 50 millimeters is about two inches. No one was going to go there anyway cause it gets impossible to run in it. So maybe it was going to be self limiting. Anyways, so who knows whether the rules actually make much difference.

Keyes: So we know what the edges of the rules are now for shoes. And as you said, it's about a 40 millimeter height. And so much of the focus has been on these records, but we haven't really talked much about how this is affecting the amateur ranks. For the average person trying to qualify for Boston, are you crazy not to get a pair of Vaporflies?

Hutchinson: I wouldn't say you're crazy not to get a pair of Vaporflies, or a competing shoe, but if you don't, you're putting yourself at a disadvantage. Now maybe, maybe that, that racing disadvantage will be offset by your sense of moral superiority. Everyone has to make their own bargains with the devil. And it's not just about shoes. We make these bargains with all sorts of things, whether it's taking caffeine or beet juice or, you know, whatever the situation is.

But yeah, I think there's no doubt that this effect has, or the effects of these shoes has trickled down to all sorts of competitive levels. I had a friend who was trying to set the over 50 Canadian half marathon record last fall. And you know, he knew what he had to do. I think it was the record was 01:15 or something, and then a few weeks before, all of a sudden, out of the blue, someone ran 01:13, took two minutes off the record, and he was like, how the heck did that happen? It was someone that was wearing the Vaporflies. And then he went to his goal race and he ran 01:15 and he didn't even win his age group. Someone else completely different also ran 01:13 in the over 50 category for this half marathon.

And he looked through the weight race photos and he was 15th in the race and he said 14 other people in front of him, 14 of the 15 people in front of him were wearing Vaporflies. So, you know, we're talking local races in the over 50 categories. People are like, what the heck is happening?

And for sure Boston qualifying times and things like that are gonna reflect the prevalence of these new shoes.

Keyes: So are you running in them?

Hutchinson: So I have a pair of the original vaporfly 4%. I got them as a review copy or a viewed review pair, actually just before I moved over to Outside Magazine back in 2017 and they arrived just when I, when I already decided to go. So I was writing for Runner's World at the time. I got them from Runner's World. I couldn't review the for Runner's World cause I'd moved to Outside. I couldn't review for Outside because I'd got them from Runner's World. So I said, I'm just going to put these in a box and I'm not going to run in them. I'm not going to do anything. Cause I had a ton of ambivalence about what does running mean to me. Why am I heading out there on weekends to race? What does it mean to me if I'm faster than last week or last year, if effectively it's just because I put on a different pair of shoes.

At the same time, I love running faster. So, definitely another voice in my head that was quite loud saying, settle down, Mr. Precious, and just get out there and, run as fast as you can. So eventually, maybe a year later, I ran a  5K in them cause I thought, I've written a billion articles about the Vaporfly. I should know how they feel in a race.

Keyes: I love seeing how the inside of your mind works.

Hutchinson: My, my therapist would have a field day. So I ran one, one race in them and they felt cool. I have no idea. Because I didn't run a lot of races that spring, I don't know whether they made me faster or slower, but I'm a data guy, I believe they did.

And they've been sitting there ever since. And I admitted this to someone the other day. I said, I'm signing up to run the London marathon next month. And I had sort of decided in my head that I'm going to run, I'm gonna get them out. And I'm going to run the London marathon. Because I'm a middle distance guy. A marathon is a long way from me. It doesn't feel good. One of the things that people have said about the vapor flies is, yeah, yeah, maybe they make you a couple of percent faster, sure, but they also help you make your legs feel so much better at the end of a long, hard run. Let's say a marathon. They help you deal with the pounding. This is what I hear from a ton of people. They're like, you'll never pry the Vaporflies from my cold, dead hands because they allow me to run more as an over 50 runner than I have in 20 years, they just allow my legs to deal with the pounding.

And I thought, I could really use that. I'm not in great marathon shape, my build up hasn't gone well. I would love to be able to enjoy the experience of running London without sort of hobbling for the last 10 miles like I might otherwise. So again, here's my twisted logic, right? But I've had a few people call me out on that and say, well, that's the point of a marathon. A marathon is supposed to be hard.

Keyes: You gotta suffer

Hutchinson: Yeah, exactly. Why are you trying to take the suffering of the marathon? And I don't have a good answer for that. So I don't present this with a tidy moral at the end saying, so therefore I know what I'm going to do.  I think I'm probably still gonna, if London takes place given all that’s going on these days, I will probably run in them, but, if it helps any of the critics, I'll feel guilty.

Keyes: We'll know here at Outside that your time is tainted.

Hutchinson: Exactly. It will not go on the Outside leaderboard.



Roberts: Alex Hutchinson writes Outside’s Sweat Science column, about the science of endurance and adventure. You can follow his reporting at science

This episode of the Outside Podcast was brought to you by Hydroflask, makers of the new Trail Series Bottle, which lets you go farther with less weight. Learn more about it and purchase yours at

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Outside’s longstanding literary storytelling tradition comes to life in audio with features that will both entertain and inform listeners. We launched in March 2016 with our first series, Science of Survival, and have since expanded our show to offer a range of story formats, including reports from our correspondents in the field and interviews with the biggest figures in sports, adventure, and the outdoors.