Supershoes are reshaping distance running

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Narrated by NOAA Listen to more of the best articles from the world's biggest publishers on the NOAA app or@newsoveraudio.com Jonathan W. Rosen writes Super Shoes Are Reshaping Distance Running the track at Moy University's Eldoret Town campus doesn't look like a facility designed for champions. Its surface is a modest mix of clay and gravel and it's 10 meters longer than the standard 400. Runners use a classroom chair to mark the start and finish. Yet it's as good a place as any to spot the athletes who make Kenya the world's greatest distance running powerhouse. On a morning in January 2024, nearly a hundred athletes, including Olympic medalists and winners of major marathons, have gathered here for speed work, high intensity intervals that the best runners make look effortless. The track is packed with so much talent that it is easy to miss the man of the moment A gangly runner in a turquoise shirt and thick soled Nike shoes. In just over a year, Kelvin Kiptom had gone from virtual unknown to global phenom, running three of the seven fastest marathons in history and setting the official men's world record 2:35 in Chicago in October 2023. On this day, he was less than three months out from his next race in Rotterdam, where he planned to try for something once unthinkable, completing the 26 mile 385 yard event in less than two hours. Although fans were left in awe by Kiptom's Chicago triumph, not everyone celebrated the shoes that had propelled him to victory. Since 2016, when Nike introduced the Vaporfly, a paradigm shifting shoe that helped athletes run more efficiently and therefore faster, the elite running world has muddled through a period of soul searching over the impact of high tech footwear on the sport. The vaporfly was only the beginning. Today, most major brands offer multiple versions of the Super Shoe, a technology that combines a lightweight energy returning foam with a carbon fiber plate for stiffness. Super Spikes, based on a similar concept, are now widely used on the track as well. Performances have adjusted accordingly since 2020, according to the sport's governing body, World Athletics. Runners wearing so called advanced footwear technology have broken all road and outdoor track world records in distances from 5,000 meters to the marathon, a concentration unlike any in the sport's modern history. Some of the most impressive feats have come in the marathon. In a 2019 exhibition that wasn't eligible for records, Kenya's Eliud Kipchoge covered the distance in an astonishing 11 hour, 59 minutes and 40 seconds. In September 2023, Ethiopia's Tegst Asefa lowered the women's world record by more than two minutes. In Berlin, running 2 hours, 11 minutes and 53 seconds in the ultralight Adidas Evo 1, a shoe designed to be worn only once for his own record. Two weeks later, Kibtum wore the slightly heavier yet Uber bouncy Nike AlphaFly 3. The uninitiated could have been forgiven for thinking the white platform shoes, which almost looked designed for walking on the moon, belonged on a Sci Fi set rather than the streets of Chicago. To some, this is all a sign of progress. In much of the world, elite running lacks a widespread following. Record breaking adds a layer of excitement. And as I'd hear repeatedly from top athletes and coaches in Kenya, the shoes have benefits beyond the clock. Most important, they help minimize wear on the body and enable faster recovery from hard workouts and races. Still, some argue that they've changed the sport too quickly. Not only has it become hard to compare new records fairly with old ones, but the steady stream of footwear innovation has brought unending speculation over which brand's shoes are best, and critics say that places too much emphasis on gear at the expense of runners ability. Laboratory research also suggests that some runners get a greater boost from the technology than others, depending on their biomechanics. Ross Tucker, a South African sports scientist and outspoken super shoe critic, has argued that these differences make it effectively impossible to evaluate performances between different athletes. Independent of this nagging doubt over what the shoes do, how much of Kiptum's success was due to his talent, training drive and mental toughness? And how much to his body's responsiveness to Nike's tech? It's difficult to know, and tragically, he's not around to offer input. A few weeks after I saw him in Eldoret, at the city of several hundred thousand that serves as Kenya's unofficial running capital, he and his coach, Gervais Hekisimana, were killed in a late night car crash en route to the nearby town they used as a base for training. Shoes were the last thing on the mind of Kenya's running community in the wake of Kiptum's death. Yet his Dramatic rise offers a window into their significance. Although the shoe tech revolution has affected runners the world over, in few places has its effect been more pronounced than Kenya, where running is not only a sport but an exit strategy from a life of poverty. In this sense, the new high tech shoes are something of a mixed blessing, giving a boost to established runners with company sponsorships while forming an obstacle to those still pining for their big break. Even the cheapest models here sell for well over $100, no small sum for young people who mostly come from disadvantaged backgrounds. Today, most Kenyan athletes, whether beginners or household names with six figure shoe contracts, have come to accept that there's no turning back, that even the most elemental of sports is not immune to scientific innovation. Still, the new shoes are transforming the sport in myriad ways, throwing new variables into training and racing, exacerbating inequalities between athletes and altering the collective imagination of what performances are possible. They're also writing a new tech fueled chapter to one of the sports world's most unlikely how a small corner of one African country became such a dominant force in running, and how running in turn, became the stuff of dreams for so many of its youth. To understand the impact of shoes on running performance, it's helpful to think of the human body as a vehicle. In a long distance event like the marathon, competitors are limited by three physiological factors. VO2 max, the maximum amount of oxygen the body can absorb, is akin to an engine's horsepower. It effectively measures the upper limits of a runner's aerobic capacity. Lactate threshold, the point at which lactic acid accumulates in the blood faster than the body can remove it, is like the red line on a dashboard tachometer. It tells you how close you can run to your VO2 max without succumbing to exhaustion. The third parameter, range running economy, describes the rate at which a runner expends energy similar to gas mileage. A light, aerodynamic coupe will use less fuel or energy to travel at a given speed than a hulking suv. So too will a lithe, efficiently striding marathoner. It is running economy that's affected by footwear most obviously when it comes to weight. As a leg in stride moves through space, added weight closer to the end, namely the foot, has a greater energetic cost than weight closer to the center of gravity. Soles made with foams that are soft or compliant good at storing mechanical energy and resilient good at returning it, can also lead to significant energy savings. Studies have shown that shoes with stiffening elements like like plates can improve running economy as well by reducing the muscular effort of the feet. The trick for shoe manufacturers has long been to optimize these properties, and for much of competitive running's history, they weren't particularly good at it. As recently as the 1970s, shoes worn for racing had clunky rubber soles and stiff leather or canvas uppers. Not so different from the o' Sullivans live rubber heels that propelled the American Johnny Hayes to victory in the marathon at the 1908 Olympics. The first run at today's standard distance. The 1975 release of the first shoe with a midsole made from ethylene vinyl acetate eva, an air infused foam, heralded a new generation of footwear that was lighter and bouncier. With a few exceptions, innovations over the next four decades would focus on making EVA shoes as light as possible. That all changed with the vaporfly. After its release, most attention focused on its curved carbon fiber plate, which many suspected functioned like a spring. Research has shown that to be incorrect. While the plate may add some energy saving stiffness, says Wouter Hoogkammer, a professor of kinesiology at the University of Massachusetts Amherst, its main benefit appears to be in stabilizing the technology's most vital component, a thick midsole material made from a foamed polymer known as polyether blockamide, or PEBA. Not only is this foam light, tests in 2017 at Hoog Kammer's lab, then at the University of Colorado, Boulder, found that a vaporfly prototype stored and returned significantly more energy than the leading marathon shoes at the time. The EVA sold Nike Streak and the Adidas Boost, made with a thermoplastic polyurethane. HughKammer's team also recruited 18 high performing athletes and tracked their energy expenditure, measured in watts per kilogram of body weight, as they ran for five minute bouts on a treadmill at different paces. In all three, the vapor fly, they found, improved running economy by an average of 4%, in part by increasing the amount of ground covered with each stride. More recent studies have found a slightly smaller benefit when comparing the vaporfly and other super shoes with control shoes over short distances. However, preliminary data from a Brigham Young University study, which tested subjects during runs lasting an hour, suggests that super shoes may offer a greater running economy benefit as an athlete progresses through a race, in part because softer foams help reduce muscle fatigue. A runner with a 3% running economy benefit in the lab might be at 4 or 5% at the end of a marathon, says Ian Hunter, a professor of biomechanics who led the research. Although it's widely accepted that better running economy translates into faster racing. The exact impact on elite performances is subject to uncertainty. At world record marathon pace, statistical models predict 4% better running economy would lower time by more than 3 minutes. But but few runners and coaches I spoke with in Kenya believe the technology is worth that much, even as they acknowledge that it's become essential to competing at the highest level. Many note that footwear has advanced alongside better marathon specific training and new hydrogel based sports drinks that make it possible to digest more calories during races. There's also the scourge of doping. Drug related offences had left 81 Kenyan athletes ineligible to compete in world athletics events as of May 1, 2024, though Kipchoge has never tested positive and neither had Kiptum. Speaking at the track after Kiptum's January 2024 workout, his coach Hakizi Mana estimated that the shoes improved Kiptum's marathon time by a minute or perhaps a little more. The technology, he stressed, was only one factor among many that contributed to Kiptam's rapid ascent. There was the punishing training, the way he'd attack with so much confidence in races, the stoicism with which he approached the running lifestyle. On top of that, there was the influence of the generations before him who helped transform a land of unparalleled running talent into into the home of champions. While Kenya's runners are renowned today for their marathoning dominance, the country first emerged on the global stage in track races. The watershed moment came at the 1968 Mexico City Olympics where Kenya won eight medals in track and field, including gold in the men's 1500 meters, 10,000 meters and 3000 meter steeplechase. For the next two decades, the country's athletes largely shied away from the marathon. According to Moses Tanwee, a Kenyan who won the Boston Marathon twice in the 1990s, many men believed the event would prevent them from fathering children. Eventually though, as money shifted away from the track and towards the roads, the longer distance had greater allure. Today, the winner of a major race like Boston can can expect a several hundred thousand dollars payday between appearance fees, prize money and shoe company bonuses. As of May 2024, according to World Athletics, Kenya born athletes accounted for 28 of the event's all time 50 fastest men and 17 of its 50 fastest women. Kenya's outsized success is also closely linked to the concept of running economy Studies of the Kalonjian, a community of nine closely related tribes that produce the majority of Kenya's top athletes point to several physical attributes more common in this group that are conducive to an energy efficient gait, including thin lower legs, long Achilles tendons and a high ratio of leg length to torso. Active childhoods in the highlands to the west of the Great Rift Valley, where altitudes between 6,000 and 9,000ft help boost aerobic capacity, is likely a component of their success as well. It's the prospect of financial rewards, though, that drives participation and transforms raw talent into records. Although Kenya is one of Africa's most industrialized countries, even top university graduates struggle to find well paid jobs in the villages and small towns of the Rift Valley region, where economic prospects are especially limited. Many are drawn to running by default after high school. If you don't continue with your studies, you can run or you can be idle, says Brigid Koskay, a Kenyan who held the women's marathon world record before acefa. So you run, you try your best in it is in this context that the stakes of shoe technology are so high. In top competitions, places worth tens of thousands of dollars, representing new homes for parents and school fees for children can come down to seconds. For a few years after Nike's release of the vaporfly, the odds were stacked against runners sponsored by other companies whose contracts prevented them from using competitors products. The gap was partly psychological. Cyprien Kotout, an Adidas sponsored runner who's won marathons in Paris and Hamburg, recalls feeling disillusioned mid race next to Nike shod competitors. Some sought out workarounds. One cobbler in Ethiopia gained fame for his skill in attaching vaporfly soles to Adidas uppers, thereby helping some Adidas runners stealthily utilize the Nike tech. Today, the playing field is far more level, at least among established Pros. At the 2 Running Club, an Adidas sponsored camp set amid rolling tea fields south of Eldoret, Kutout and his teammates give me a glimpse of their Adizero carbon fiber lineup. There's the ultra padded Prime X for long sessions on pavement. The more compact Takumi Sen for speed work. One pair of the featherlight black and white Evo, which Kutout used to run a personal best of 2 hours, 4 minutes and 34 seconds in 2023. In Amsterdam, Claudio Berardelli, the group's Italian coach, estimates that his runners cover at least 60% of their mileage in super shoes. For most, they've become as vital to training as they have to racing. Not only do they enable faster workouts, says Benson Kipruto, a club member who won the Tokyo Marathon in March 2024 and finished second to Kiptom in Chicago last fall. The softer foams also promote quicker recovery, to the point where the day after a hard session, your legs are a bit fresh. Many credit the shoes with keeping runners healthy. David Kirui, a physiotherapist who's treated many of Kenya's top marathoners, estimates that overuse related injuries like stress fractures, Achilles tendinitis and iliotibial band syndrome are down at least 25%. Several veteran runners tell me the shoes have helped extend their careers and therefore their earning power. In the old shoes, after 10 marathons, you'd be completely exhausted, says Jonathan Mayo, who's been an elite road racer since 2007. Now, 10 marathons are like nothing. Runners like those in Barardelli's group are a chosen few. The majority of athletes training in Kenya have never made any money from the sport. Many run in second hand shoes gifted by friends or purchased in local markets. And few can afford super shoes of their own. One day in Etain, a small town north of Eldoret that clings to the edge of the Rift Valley escarpment, I meet daisy Candy, a 23 year old who moved here after high school and is among the hundreds of aspiring pros who toil along the town's clay roads each morning. Her goal is the same as most get noticed by an agent, most likely a foreigner, who'll provide gear, arrange races outside the country and in some cases, negotiate a contract with a shoe company. Among E10's legion of dreamers, Candy is luckier than most. Her parents see her as a future breadwinner, so they've supported her quest and even sold a plot of farmland so they could buy her a pair of neon green and pink Nike Alphaflys. The shoes were cheaper in E10, approximately $180, than they would have been in the U.S. it's an open secret that some runners with sponsorships sell shoes they get for free to local shops, which resell them at below market prices. That money nonetheless represents a lot of sacrifice. Candy pays roughly that amount for a year's worth of rent on the small room she keeps at the edge of town. The cost of the shoes, which she refers to as her sub 2 for the idea of a below 2 hour marathon, doesn't make her resentful. Instead, she says, having the latest gear helps keep her motivated. Still, while she uses them only for fast runs twice a week, as well as in occasional local races, their soles have considerable wear, and she doesn't have a plan for a replacement. By then I'll have gone, she said, referring to racing outside Kenya. When I asked what she'll do for her next pair, I have hopes. Although super shoe technology has raised the cost of doing business for Candy and others like her, it's most controversial for its role in skewing results at the very top. Hoog Kammer's landmark study of the Vaporfly, which found that the shoes improved running economy by 4% on average, also found that the benefit ranged from roughly 2.2to 6%, depending on the athlete. Subsequent research involving other super shoes has documented a similar range of responses. One 2023 study by Adidas affiliated researchers, which tested seven elite Kenyans in three carbon fiber prototypes and a traditional racing flat, recorded a runner using 11% less energy in one shoe and a runner using 11% more energy in another. Melanie Knopp, the study's lead author, cautions that each athlete was tested in each shoe only once and that some of the subjects were unfamiliar with running on a treadmill. Nonetheless, researchers generally agree that individual athletes respond to some shoes better than others. Why isn't entirely clear. Hoog Kammer estimates There may be 20 variables at play, including weight, foot length, calf muscle strength and whether the runner strikes the ground with the forefoot, midfoot or heel. Shoe geometry matters as well. Abdi Nagiai, a Dutch marathoner who trains in E10 and finished second to Kipchoge at the Tokyo Olympics, says he struggled with the first two versions of Nike's Alpha Fly, and as a 120 pound heel striker, it forced him to skip in a way that felt unnatural. He says the newest AlphaFly model, which has a greater drop in stack height or foam thickness from heel to toe, is a much better fit. What all this means for the marathon's integrity is a hotly debated topic today. Many pro runners in the west undergo treadmill based metabolic tests to to determine which shoe works best and, in some cases, which company to sign with. That's less common in Kenya, where greater competition leaves athletes less room to negotiate among runners I spoke with most of those with shoe contracts said their sponsor has a model they like, but it's difficult to know if it's their absolute best fit. Even if it is, some suspect that certain runners are better suited to the super shoe technology more broadly. If everybody is in their ideal shoe, are there still some people who'll get more benefit than others? Asks Dustin Joubert, a super shoe expert and professor of kinesiology at Saint Edwards University in Austin, Texas. The answer is probably yes. Despite the benefits his runners gain in training, Berardelli says the shoes have introduced question marks in a marathon. Today, he says in it's less clear than ever whether the winner is indeed the runner who's the strongest or has the smartest racing tactics. Steven Chirono, a Kenyan who competed for Qatar as Saif Sayd Shaheen and held the world record in the 3,000 meter steeplechase from 2004 until it was broken with the aid of super spikes in 2023, believes World Athletics should have placed greater restrictions on the technology before it was too late. Although the global body maintains limits on sole thickness and prohibits the use of shoes that aren't made available for sale, these guidelines are meant to help steer innovation, not squelch it. Cirono tells me he's a big fan of Formula One, the global motorsport, but worries that running in its focus on performance engineering is becoming too much like it. Too often the conversation is now about the shoe and not the person wearing it. He if there's one thing super shoe advocates and critics can agree upon, it's that Kelvin Kiptum operated on another level. His margin of victory in Chicago, nearly three and a half minutes, was so large that some joked second place Kipruto had won the race for mortals. Like most runners in Kenya, Kiptum grew up in a farming family where money was tight. When he began training as a teenager, he often ran barefoot. Occasionally, pros he tagged along with gave him shoes. Among them was Hakizimana, a Rwandan who trained near Kiptum's home and took him on as a protege when his own running began to falter. After a stint training to be an electrician, Kiptum began running full time in 2018. Four years later, in his marathon debut, he ran the third fastest time in history. Atypically, in all three of his marathons, he ran the second half faster than the first. Perhaps because Nike's Peba foam had helped save his legs, or perhaps because his training was so grueling, most world class Kenyan marathoners top out around 220km per week. According to Hakizimana, Kiptam would often run up to 280 or roughly a marathon's distance every day. One month to the day after, I watched Kiptam circling the eldoret track, completing 1000 meter repeats at roughly the pace of a two hour marathon. I gather with hundreds of others on a property he'd purchased outside town where he is being buried. According to Kalonjin tradition, the crowd again includes a who's who list of champions. This time, instead of running gear, they are dressed in suits or black T shirts emblazoned with the record holder's image. Their mourning is both for a man who died far too young. Kiptam was listed as 24, though he was likely at least a few years older and for a remarkable performance that many had expected to be just around the corner. Entering Chicago, Kiptum had been dealing with an injury and wasn't even in top shape, according to his training partner Daniel Kemboy. Ahead of Rotterdam, Kemboy says he was so confident, very few in Eldoret doubted he would shatter the two hour barrier at some point that afternoon. My mind drifts to the shoes. Kiptam had been an extraordinary competitor regardless of what was on his feet. Still, absent super shoe technology, the the prospect of a sub 2 hour marathon would never have been part of his dramatic rags to riches story. In this sense, the shoes didn't minimize his greatness as critics like Cirono feared. If anything, they helped build his brand and turbocharged his pursuit of the Kenyan running dream of achieving a better life through sport. Tragically, Kiptam's path was cut short when he was only getting started. But someone else in rigid shoes with bouncy soles will come along to blaze their own. You are listening to MIT Technology Review where Jonathan W. Rosen writes super shoes are reshaping distance running. This article was published on 25 June 2024 and was read by Peter Handley for NOAA.