This is Eliud Kipchoge.
On October 12, 2019, he ran a marathon in under 2 hours, a barrier no human had been
able to break in the preceding 13.8 billion years—and these are the Nike Vaporflys.
They also ran a marathon in under two hours—and, coincidence alert, it just so happens they
did it whilst strapped onto Eliud Kipchoge’s feet.
And because we can never once just enjoy something, the question of how much of that 1 hour, 59
minute and forty-second marathon can be credited to this guy, versus how much can be credited
to these guys, quickly became a subject of enormous controversy—so much so that some
versions of the Vaporfly have now been declared illegal in competition.
The modern running shoe dates back to 1865.
They looked like this, and while they were very good at looking like a vampire’s house
slippers, they were not very good at helping people run fast.
In time, running shoes evolved—1917 saw the advent of rubber soles, in 1972 Nike introduced
the famous waffle sole, and in 2020 Mizuno made whatever this is.
Over this period, running shoes basically standardized into three parts: the upper,
the midsole, and the outsole.
The upper is this part—it’s designed to be light and basically just keep the shoe
on your foot.
The outsole is this part—it makes contact with the ground, providing traction and durability.
People used to care a lot about outsoles, but these days, outsoles are out.
What’s in?
Midsoles.
The midsole is typically made of some type of foam, and provides cushioning for the runner’s
foot.
The key to a great midsole is energy return: how much of the energy the runner expends
when pushing the midsole down is returned when the midsole bounces back up?
Most modern shoes return around 50-65% of energy back to the runner.
The Nike Vaporflys return about 85%.
So, what makes the Vaporflys so good?
Well, let’s go deeper into energy return.
Energy return comes from a combination of compliance and resilience—which coincidentally
are also the two traits I look for in my unpaid interns.
In physics, compliance is how much something will give when you put pressure on it.
Resilience is how much of the pressure absorbed will be returned back.
For example, sand is very compliant, but not very resilient: if you find yourself running
in sand, either as part of an inspirational montage or a perspirational worm-chase, you’ll
find it’s difficult, because while the sand gives a lot beneath your feet, it doesn’t
return the energy back to you.
A steel plate, on the other hand, is very resilient but not very compliant—however
far you press it down, it’ll return back up…but it’s really hard to compress steel.
Nike’s Vaporflys provide unmatched energy return by striking a perfect balance of compliance
and resilience, thanks to two key innovations.
The first is this: Pebax foam, which Nike gave the name “ZoomX foam,” because Pebax
sounds like a decongestant and ZoomX sounds cool as hell.
For a long time, midsole foam in running shoes was kept thin to reduce weight—but Pebax
foam is so light that Nike was able to justify a much thicker midsole—in the case of the
Vaporflys, 40mm.
The other key to the Vaporflys is this: a super-resilient carbon fiber plate that runs
the whole length of the shoe.
Combined, the thick foam and sturdy plate strike a perfect balance between compliance
and resilience: Vaporflys have been shown to improve a runner’s overall efficiency
by 4%.
Now for some things, like a Rotten Tomatoes score or the retention on this video, a 4%
change may not matter all that much, but in running, it’s huge.
In the 2016 Olympic marathon, 4% was the difference between first place and 15th place.
The top three finishers in that 2016 Olympic marathon, by the way, were all wearing Nike
Vaporflys.
That’s because Nike secretly launched the Vaporflys at those Olympics, which, depending
on who you ask, was either an incredible Don-Draper-level-genius marketing move, or it was cheating.
If you ask the cheating camp, they’ll say that sports should be about humans competing
against each other based on athletic ability—not based on who has the fanciest gear.
And it started to seem like in order to win a race, Vaporflys weren’t just an asset—they
were a necessity.
In fact, some athletes sponsored by other shoe companies have been caught racing in
Vaporflys with the logo Sharpied out.
That’s how much better they are.
Until 2020, the rules from IAAF, the international governing body for track, were simple: “Shoes
must not be constructed so as to give athletes any unfair advantage or assistance.”
So the question was: are the Vaporflys an unfair advantage?
This question, of so-called “technological doping,” is not a new issue.
Remember the 2008 Olympics, when all the swimmers wore those weird bodysuit things that made
them look like they were about to lose the Hunger Games?
They were called LZR racers, and in 2008, swimmers wearing them won 98% of Olympic swimming
medals, and broke 17 world records, leading FINA to ban body-length suits.
On January 31st, 2020, World Athletics announced a highly-anticipated rule change, limiting
midsole thickness to a maximum of 40mm, and allowing for no more than one stiff plate
in a midsole.
While this ruling made certain Vaporfly prototypes illegal—including the sprinter-specific
Viperfly, and a three-carbon-plated version of the Alphafly—by and large, it was a win
for Nike, whose core Vaporfly products remained legal, meaning that come Paris 2024, anyone
who wants a medal had better either get a Nike sponsorship, or a Sharpie.
Speaking of sponsorships, I’m incredibly excited for this one, because I’ve got a
new series out that’s a dual-release on CuriosityStream and Nebula called Extremities,
where I explore how and why the world’s most remote settlements exist.
What’s cool about my new series Extremities is that it isn’t new at all: Extremities
was a podcast and then a YouTube channel, but it was always too expensive to produce
for it to be profitable.
But thanks to CuriosityStream and Nebula, we have finally been able to finally make
the version of Extremities we always dreamed of—with incredible footage, super high-quality
motion graphics, and the time to do a ton of interviews and research.
Once you’ve watched Extremities, you can check out other Nebula-exclusive content:
Half as Interesting’s Crime Spree series, the HAI bricks special, our three-part trivia
show, Wendover documentaries, Tom Scott’s Money, Real Life Lore’s Modern conflict
series, and so much more.
Weirdly, the best way to get Nebula—which by the way is the creator-owned streaming
site I started with a ton of other educational YouTubers—is with the CuriosityStream-Nebula
bundle.
For weird budget and marketing reasons, it’s actually cheaper to buy the bundle deal and
get access to both CuriosityStream and Nebula than to buy either individually—only about
$1 a month.
CuriosityStream, in addition to being home to Extremities, also has a ton of other incredible
documentary content, including the great Boston, about the Boston Marathon.
So get the bundle deal, for about $1 a month if you pay annually, at curiositystream.com/HAI,
and check out my new series Extremities.