Winning a second consecutive international half-marathon title was a big ask for Netsanet Gudeta. Half an hour into the race in Gdynia, Poland, the 29-year-old Ethiopian ran in a pack with seven of the best runners in the world.
Some of them — like Joyciline Jepkosgei and Zeineba Yimer — Gudeta had handily beaten in 2018, at the last edition of these championships in Valencia, Spain. But others, like current world record holder Ababel Yeshaneh and 2016 champion Peres Jepchirchir, were coming into the race having each set a world record in 2020. And a lot had changed in the past couple of years — especially with shoe technology. Luckily, Gudeta's sponsor, Adidas, finally had a carbon fibre shoe of its own and she had them on her feet. The playing field felt even — at least as she and her rivals stood at the start line.
The race was anybody's to win until a force stronger, more abrupt and less expected than the insidious buildup of lactate eliminated three athletes from the pack, including Gudeta.
In fact, she was the first of the seven to lose contact with eventual winner Peres Jepchirchir, but not because she couldn't handle the world-record pace — it was her shoes that couldn't handle a simple turn in the road.
It happened near the end of the ninth kilometre. Taking a corner and running freely to the right of a chaotic entanglement of seven tightly-packed contenders, Gudeta seemingly slid off to the side of the road, as if she were suddenly running on ice.
Like a defending champion is expected to do, she got back up. But by the time she found her stride again, it was too late. The pack seemed to sense the moment to shed a contender and surged away from her. Gudeta put in a furious effort, but was never able to recover all that lost ground, and wound up finishing in a disappointing eighth place.
Eight kilometres later, the force of gravity took two more victims. Yeshaneh who, until then, was often leading the charge and running just off the pace of her own world record, tumbled. On her way down, she destabilized Jepkosgei — the reigning New York City Marathon champion — who had led for several of the race's first 50 minutes. Jepkosgei spent just half a second on the ground, but it was enough to ultimately relegate her to a sixth place finish. Yeshaneh battled back, but had to settle for fifth.
Meanwhile, Jepchirchir ran masterfully in the front, holding off Melat Yisak Kejeta of Germany, and squeezing by 21-year-old Yalemzerf Yehualaw of Ethiopia in the final bend. All three broke the women's only world half-marathon record (full results of the 2020 championship here.)
Under Gdynia's overcast sky, unfolded the fastest men's and women's races in championship history. No woman had ever broken 66 minutes at a world half-marathon championship. This year, six runners did. The men's race was won in a championship record, and 10 men — an all-time high — broke the one-hour mark. All this with no lead pacers.
Those results surely prompted the Captain Obvious you invited to your viewing party to make a comment that, at this point, almost feels stale: it's because of the shoes. It's the SHOES.
Well, yeah. Obviously.
Eliud Kipchoge might have tried to convince the masses at a London Marathon press conference last month that it's in fact the legs that do the running, and that the new foam and carbon technology infused in our sneakers is merely incidental to the massive breakthroughs distance runners are making around the globe. But The New York Times and (with the help of fitness tracking app Strava's data) played devil's advocate with running's Philosopher King quite convincingly. Last year, the Times published a massive study, and showed that carbon plated shoes (well, at least the Nike Vaporfly) make you faster, me faster and everybody else faster (including Eliud Kipchoge) — and by a lot.
By now, it's evident that this new wave of running shoes, with their curved carbon fibre plates and thick layers of (mostly) Pebax midsole foam designed for optimal energy return, are leading to better performances. Saying that the Nike Vaporfly and its high-performing cousins changed Saturday's race is not a hot take — it's just stating the obvious.
But what if the shoes had even more influence on the final result than we think?
As did most athletes in the field, the three contenders who fell to the ground wore carbon plated footwear. Gudeta and Jepkosgei wore the new Adidas Adizero Adios Pro, and Yeshaneh wore the Vaporfly Next%. And while using the maximum amount of foam allowed by World Athletics may produce blazing fast times, it might be time to investigate more closely how cornering on such a high platform affects balance.
A seemingly fast-growing body of research tells us a lot about the advantages of carbon plated footwear, and about how they might change injury risk and alter one's stride. But when it comes to learning about their stability, we are limited to the results of a small number of studies, common sense and quips from Kenenisa Bekele.
An early knock on the new wave of shoes is that their unusually tall stack height (caused by the combination of midsole foam and carbon plates) could compromise balance.
Before Nike launched the Vaporfly in 2016, the average stack height of a running shoe was roughly 31mm. But when Nike proved that a lightweight, thick midsole could dramatically increase energy return upon contact with the ground, performance shoes got taller by the year. In January, World Athletics banned road running shoes taller than 40mm from international competition.
A greater stack height might lead to faster times, but some researchers have posited that running on a tall shoe can increase torque upon landing, and can mask our sense of where the ground is, effectively compromising balance and stability.
It's for that reason that Kenenisa Bekele is not a fan of the Nike Alphafly Next% — the tallest shoe on record and design seemingly used by World Athletics to create the ceiling for the extreme lengths that the shoe industry can venture in pursuit of even faster times. Before pulling out of this year's London Marathon, Bekele announced he would race in the Vaporfly Next% instead of its updated model, because "(the Alphafly) is not stable under the foot. It's really unshaped, it's really soft," the Ethiopian said. Bekele also suggested he heard of several other of his peers having the same qualm with the Alphafly.
Former Nike athlete and 800m Olympian-turned YouTuber Nick Symmonds also criticized the Alphafly in a review video. He said they make him slip when running around corners and he feels like "I'm falling off the top of that 40-mm stack height." At around 3:00/km pace, going down a hill and on a sharp turn, that must feel like running off a mini cliff.
And stability troubles are not unique to Nike's version of the shoes. Molly Huddle, the two-time American Olympian chose not to wear Saucony's carbon-plated prototype for last February's U.S. Olympic Marathon Trials because it caused her pains and made her feel unsteady.
We are still mostly limited to anecdotal evidence about the shoes' shortcomings in stability, as there is not yet enough data to prove that the Alphafly, the Saucony Endorphin, the Adizero Adios Pro and its carbon-infused analogs make its users prone to falls. Only the runners themselves know for sure if this was the reason for Saturday's two momentous wipeouts. But at this point, it might be worth it for these brands to study whether or not these shoes, seemingly built solely for running fast in a bubble, could be altered to decrease the chance of tumbles and, ultimately, better fulfill their purpose, as the only place a runner can race a marathon in an even straight line is on a treadmill.
Although Nike, Adidas and other brands obviously use a stable of wear testers, and put thousands of miles on their prototypes before they go to market, these companies seem to be designing a shoe that’s akin to a Formula One car — the end game is performance and there is no room for compromise. But the truth is that real-life road race courses (even controlled ones on closed 5K looped courses) seem to demand a touch more versatility and flexibility in the technology. We’re out there racing La Mans, not Monza.
Perhaps in the next design evolution of these shoes will start on the streets, and then finish in the lab.
I'm sure Netsanet Gudeta and Ababel Yeshaneh wouldn't object.