Runners call them supershoes.
They first appeared as prototypes in the 2016 U.S. Olympic Team Marathon Trials, where three of the six who made the team wore them. At the time, nobody noticed, because the manufacturer, Nike, wasn’t yet advertising them, but even if people had noticed, it’s unlikely they would have paid much attention.
After all, says Rodger Kram, a physiologist and biomechanist at the University of Colorado, Boulder, “every shoe company [always] said, ‘Our new shoes are better.’”
This time, however, such a claim would have been right. The best comparison is to the high-tech swimsuits that took the 2008 Olympics by storm. If you weren’t wearing one in Beijing, your chances of a medal were close to nil.
The results were so stunning that American swimmer Tom Malchow, who won the 200m butterfly eight years earlier in Sydney, asked a coach how much better the suits would have made his gold-medal time of 1:55.35. The answer: “three seconds faster”—an enormous amount in a sport that can be won or lost by hundredths of a second.
Shoes enhance speed by cushioning the impact of your foot against hard pavement, packed dirt, or even a track. Without them, you have to do this with the muscles and tendons of your foot and leg, and while these muscles and tendons act like springs, absorbing energy from one stride and releasing it into the next, that still takes effort.
“If you put a slab of squishy foam between your foot and that hard surface,” Kram says, “your muscles don’t have to generate as much force to operate [that] spring.”
The supershoes take this a step further by combining a high-performance lightweight foam with an embedded carbon fiber plate that Kram describes as looking “like a giant spoon.”
The combination of the two appears to be the secret to their superpowers, though why, Kram says, nobody knows. Initially, he says, biomechanists thought the plate might be acting as a spring, or maybe a lever. But then Laura Healey and Wouter Hoogkamer of the University of Massachusetts, Amhurst, used a saw to hack the carbon plate into smaller pieces and found the butchered shoe still worked.
So, whatever is going on, Kram says, “it’s not just the foam, [and] it’s not just the plate. It’s some combination of foam and plate.”
He compares it to the taste sensation created by Reese’s Peanut Butter Cups. Everyone knows what a chocolate bar tastes like. Ditto for peanut butter.
“But a Reese’s Peanut Butter Cup tastes different because the two ingredients are interacting,” he says.
One thing is clear, however: at the elite level, not wearing supershoes is like spotting your rivals a one-kilometer head start in a marathon.
“I had a scientist tell me it was better than taking EPO [the blood-boosting drug used by Lance Armstrong in the Tour de France],” says two-time Olympian Kara Goucher. “You’re getting three to four minutes. That completely changes the outcome of the race.”
Proof of this comes from Kram, who Nike contracted to test its prototype shoes a year or so after the 2016 Olympic Trials.
I had a scientist tell me it was better than taking EPO.Kara Goucher
In a 2018 paper, he and Hoogkamer (then at the University of Colorado) had 18 “really high-caliber runners” do 5-minute treadmill tests in three different types of shoes: the prototype supershoes, and the best conventional racing flats from Nike and Adidas. Each test was done twice, and each runner did the entire process three times, on three separate days, at different paces, ranging from 2:20 marathon pace to 3:01.
Kram’s team measured how much energy these runners expended in each test by having them wear masks that monitored the rate at which they consumed oxygen and produced carbon dioxide. They also weighed them after each test and had them sip exactly enough water to compensate for whatever they had sweated off in the prior test, thereby ensuring that they were running at exactly the same body weight, each time.
When they discovered that one runner was observing Ramadan and didn’t want to drink water during the day, they gave him bags of coins, measured out to compensate for his water loss from test to test.
All of which turned out to be scientific overkill. The new shoes didn’t just save a little of energy; they saved a lot.
“Some athletes had 6 percent savings, and some had 2 percent savings,” Kram says, “but they all had savings. The average was 4 [percent].”
Not that a 4 percent energy savings makes you 4 percent faster.
When other factors are taken into account, it’s more like 3 percent faster, but that’s actually a higher percentage than what Malchow’s coach estimated the super-swimsuits would have shaved off his 200m butterfly time. 3 percent is enough to turn a male Olympian’s 2:10 marathon into 2:06 or a female Olympian’s 2:30 into 2:25:30. At the recreational level, the effect might be even bigger.
In swimming, the super-suits persisted only two years. By 2010, they were banned, partly because they were wickedly expensive, but mostly because of an uproar over whether they constituted ‘technological doping.’
Not so the supershoes.
Partly, that’s because many brands now have them, and prices have dropped to not vastly more than the best conventional shoes. There are also indications they may be kinder to the body, reducing the pounding that comes with long races and hard workouts. “[They’re] here to stay,” says Goucher.
What this means for the sport isn’t as clear. Goucher thinks it is rapidly dividing into those who remember “before,” and those who take the new, faster times as normal.
Sir Roger Bannister ran the first sub-4:00 mile on a cinder track in leather shoes whose primary purpose was to attach track spikes to his feet. Today’s mile record is 3:43.13, more than 16 seconds faster. But how much of that is advances in technology—shoes and track surfaces—as opposed to true human performance?
Jana van Stee of Portland, Oregon, wasn’t overtly thinking about such questions when, this April, she set out to break her 2:58:47 marathon personal best. Not that she was opposed to the supershoes, but they simply weren’t on her mind. She’d run the PB in 2018 in Eugene, Oregon, and now, five years later, she was back in Eugene, wanting to see how she stacked up against her prior time.
“When I race, I’m competing primarily against myself,” she says. “My main goal is to improve myself as a runner.”
So, when she ran 2:56:44—on the same course, in similar shoes, she didn’t care that she might have broken 2:51 in supershoes and beaten half the women in front of her.
“If I’m using a groundbreaking technology to get faster, I can’t credit myself and my work with that progress,” she says.
Goucher agrees. “I don’t have a problem with [technological] advances,” she says, but they do mean that comparing new times and old ones might involve a bit of apples and oranges.
“Frank Shorter and I have had this conversation,” she says. Shorter won the 1972 Olympic marathon and finished second in 1976. “I’m like, I’m just going to call myself a 2:19 marathoner, and he’s like, I’m going to call myself a 2:05, because that’s what it would be now.”
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