For most of us, the best running shoe is whichever one feels the best when you run in it. But shoe companies have been claiming that certain shoes save you so much energy that they actually make you faster. Now, we finally have data to answer that question.
We have to be clear about the bias in this study: Nike funded it. But the experiments were carried out in a respected laboratory, Alex Hutchinson reports at Outside Online and the results show that runners needed less oxygen, which means they weren't working as hard.
That translates to saving energy that you can use to push yourself to go faster. The full text of the study is available here.
Eliud Kipchoge wore Nike's Vaporfly 4% to run the world's fastest recorded marathon in 2:00:25, but there was a lot going on in that race. Nike set it up with the explicit goal of logging the first sub-two-hour marathon. (The event, plus the months of buzz about how they were training and studying the athletes, amounted to what may be the world's biggest and longest shoe commercial.)
So there was a lot more going on in that event than just putting their flagship shoes on one of the world's best athletes.
For example, Nike booked a flat race track in an optimal location with several available dates in case of bad weather. They also had three athletes make the attempt; two dropped out during the run because they couldn't keep up the pace.
Kipchoge also had an an ever-changing group of hired runners blocking the wind for him; they swapped out every few miles so he was always following right behind someone who was keeping perfect pace on fresh legs. (That kind of help isn't allowed in competitive races, which is why his time isn't eligible for the record books.)
What Makes These Shoes Special
With results like those — and the additional fact that Shalane Flanagan wore the same shoes to win the New York City Marathon earlier this month — it's hard to know whether those athletes actually owe some of their performance to the shoes.
They're clearly amazing runners who would do well no matter what they were wearing. That's why lab studies like the one that was recently published add to our understanding: they examined what happens to people who run the same standardised tests in the Vaporfly versus two other state-of-the art shoes: the Adidas Adizero Adios Boost 2 and Nike's Zoom Streak 6.
And, indeed, everybody ran a smidge more efficiently in the Vaporfly than in the other two models.
The difference between the Vaporfly and the other two shoes seems to be the type of foam used for cushioning and the springy plate sandwiched in between layers of that foam. Now that the Vaporfly is available for purchase, Wired was able to run an impromptu study of their own, looking at finish times for 138 runners in the New York City marathon including 21 wearing the Vaporfly.
These results suggest that people who wore those shoes were more likely to run negative splits (running faster at the end of the race than in the beginning). That fits with the idea that the shoe makes people run more efficiently, but there could also be a serious placebo effect that goes along with knowing you're wearing a pair of shoes that's supposed to make you faster.
The bottom line is not that we should all be running in Vaporflys. It's that if you're dead set on shaving a few minutes off your marathon time it's worth considering whether that's worth the cost. Maybe you'd be better off spending that extra cash on a few sessions with a coach to fix your form, or on babysitting time to get in some more training.
And that's not a decision that Nike can make for you.