If you are reading this I am sure you know all about the Nike Vaporfly and the general uproar it caused in the late 2010s. But in case you are curious about why someone would ever put a carbon plate in a running shoe in the first place and how the whole deal works, here is a quick primer.
The first carbon plate running shoes were made by Reebok in the early 90s, followed closely by Adidas (1, 2). Even at that point people had figured out that a carbon plate could offer an advantage, but it was an idea whose time had not yet come. The carbon fiber was so outrageously expensive that there was no way to produce a shoe that could compete with the rest of the market (remember in those days more than $100 for a pair of running shoes was kind of outrageous), and the shoe tech and knowledge needed to really optimize the effect of a carbon plate and make it something people would actually pay top dollar for didn't yet exist.
Things remained pretty quiet commercially as far as carbon fiber in running shoes went until the mid-2010s, but that doesn't mean shoe designers and engineers forgot about it; if you want to read more about some of the other developments during that time, Dave Jewell's piece on freerunspeed.com has you covered.
We however are going to fast-forward to 2016 when top Nike athletes such as Eliud Kipchoge, Shalane Flanagan, & Amy Cragg began running in some version of the carbon plate Vaporfly; it very quickly became obvious that the hype surrounding this new shoe was more than the usual brand propaganda surrounding many new running shoes (3).
So what is the deal with the carbon plate? Contrary to what some folks seem to think, it's not the plate itself that's springy, nor is it the plate that confers 100% of the advantage (meaning, you can't just stick a carbon plate in any old shoe and necessarily get the same advantage).
As far as I can suss out from the internet, carbon plate running shoes confer a mechanical advantage in a few different ways:
- While the plate itself is not particularly springy, carbon plate shoes use a new foam technology that is both incredibly squishy (it squishes a lot under your foot) and incredibly resilient (it easily rebounds back to its original shape), providing something like 80% energy return, which is very high. (4, 6, 8)
- The plate creates a "teeter totter effect,” returning energy to the runner every time their foot strikes the ground. To quote Benno Nigg, founder of the Human Performance Lab at the University of Calgary’s Faculty of Kinesiology who worked on Adidas's carbon plate shoe 20+ years ago, “You press at the front and the rear part goes up. If the rear part goes up, that means you’re going to be pushed while taking off." (4, 6)
- It also keeps the runner's big toe joint (and maybe all toes?) straighter as the toes come off the ground, which, surprisingly (at least to me) saves the body energy and helps you move through your stride more quickly. (6, 7, 8)
- Finally, the plate also seems to stabilize the ankle, reducing your “rotational force,” i.e., the work your calves would normally have to do to. (8)
There has also been a lot of anecdotal evidence from athletes that
running workouts in carbon plate shoes may allow you to train
harder/more often/do more volume because they reduce the stress on your
calf muscles so that you recover more/faster between workouts.
(Though...this may be a questionable reason for normies to run in carbon
plate shoes regularly, given their notoriously high price tags and poor
durability/lifespan.)
In 2017, we got a (legitimate) study in the journal Sports Medicine (9) that tested 18 runners in the CU Boulder "Locomotion Lab," all of whom demonstrated better running economy in the Vaporflys than in two other popular racing shoes (the Nike Zoom Streak 6 and Adidas Adios Boost 2). The runners' improvement ranged from 1.59% to 6.26% percent, putting the average right around--what else?--4%.
Which...creates kind of
paradox. Naturally, every running shoe company wants to make a better
shoe with features that will optimize the wearer's performance and make
them run faster. Like, the whole point of advertising a performance shoe
is talking about all the ways it can make you faster. But...if one
particular brand has a shoe that really can make you measurably faster as compared to other shoes, then we have a problem.
"Our shoe is the best, it makes you faster!"
"No, our shoe is the best, it makes you even faster!"
"Wait a minute, no fair, their shoe really does make you faster, that's cheating!"
"But trying to make a shoe that makes you run faster is like...the whole point?? How is that cheating??"
And so. Now, we have to have the uncomfortable conversation about shoe doping, and if that is really a thing, and if so what do we do about it other than pass a rule that says "No fair making a shoe that *actually* does what it says it does, please go back to making shoes you say make people faster and give an advantage but actually don't, really" (4).
To quote British marathoner Mara Yamauchi,
"If they say doping is not allowed because it's performance-enhancing but we're OK with these shoes which are also performance-enhancing, there's a bit of inconsistency there." (5)
Except that...the whole point of a good running shoe is to...enhance your performance. As is good coaching. And good nutrition. And recovery tools. And certain within-the-rules supplements. And the army of strength trainers, PTs, chiros, massage therapists, etc. that you can hire if you have the funds.
I won't rehash the entire debate on that point that raged from roughly 2016-2020, but I think for most people there were really two issues that felt kind of icky.
- The biggest problem was for non-Nike pro runners who were contractually obligated to run in their sponsor's (i.e., a for-sure proven inferior) shoe and for whom racing carried real, actual stakes. In that way, the carbon plate shoes really did feel a little more like doping in that you know absolutely for a fact that certain people on the line have an advantage above and beyond their genetics and training that you don't have access to.
- When the Vaporflys finally did go on the commercial market, the supply was so low compared to demand that they were almost impossible to get, and what was already the most expensive running shoe ever on the primary market would frequently end up on the secondary market at a 4x mark up. Now, we all know that for a lot of people, those advantage-conferring things mentioned above are a matter of expendable income you either have or don't, so we can't say that strength trainers and special recovery tools and so forth are equally available to everyone. Yet (almost) no one talks about how runners who have the time and resources for consistent strength training have an "unfair advantage." It's still reasonable to call those things generally accessible to many or most runners even if they aren't feasible for literally everyone. The situation with the Nike shoes in the late teens/early 2020 was fundamentally different; you just could not reasonably claim that the Vaporfly was more or less equally available to anyone who wanted it if they chose to buy it and prioritized their expendable income that way.
*** REFERENCES ***
1 - The History Of Carbon Fiber in Running Shoes (Dave Jewell, 2017)
2 - Why Choose Carbon Plated Running Shoes? (Tom Folan, 2022)
3 - The Shoes Athletes Say Will Change the Future of Running (Nike News, 2017)
4 - These Olympics are about the shoes: How the evolution of footwear tech is changing track and field (Andrea Hill, 2021)5 - If you can't beat 'em, join 'em: How Nike cornered the running shoe market (Tomas Meehan, 2021)
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