When Ethiopia’s Tigist Assefa smashed the women’s marathon world record in Berlin last September, winning the race in two hours, 11 minutes and 53 seconds, she kissed the Adizero Adios Pro Evo 1 shoes she had run in. And no wonder. In only her third marathon, she had knocked more than two minutes off the previous world record – set by Paula Ratcliffe in 2002. When another Ethiopian athlete, Abebe Bikila, broke the men’s marathon world record in his gold medal-winning run at the 1960 Olympics, he didn’t kiss his running shoes for one simple reason: he wasn’t wearing any. 

Bikila’s old shoes had worn out in training and, because the new ones gave him blisters, he didn’t wear them as he set a new world best of 2 hours, 15 minutes and 16 seconds. After the race, he explained his choice saying: “I wanted the world to know that my country, Ethiopia, has always won with determination and heroism.” That race over Rome’s cobblestone streets secured Bikila’s place in history, as the first – and only – athlete to win the modern marathon in bare feet. He was also, as extraordinary as this seems now, the first sub-Saharan athlete to win an Olympic gold medal. (Five of the past six Olympic champions in the men’s marathon were born in East Africa – as were the last three winners of the women’s event.) Racing in Tokyo in 1964, this time in shoes, Bikila triumphed again to become the first man to win this Olympic event twice. This feat has only been matched subsequently by East Germany’s Waldmar Cierpinski – who was, inevitably, accused of doping – and Kenya’s Eliud Kipchoge.

 

 

Siraj Gena walks barefoot in memory of fellow ethiopian Abebe Bikila, after winning the 'Maratona di Roma' in 2010.

 

The journey from no shoe to super shoe, which has taken half a century or so, sheds an intriguing light on the professionalisation of sport (and the consequences for competitive balance), the development of technology, the power of brands, the environmental cost of conspicuous consumption and our deepening understanding of the human foot, described by one of its most fervent and articulate admirers, Leonardo da Vinci no less, as a “masterpiece of engineering, a work of art.”

In one sense, Bikila’s triumph was an evolutionary throwback as Daniel Lieberman, an evolutionary biologist at Harvard University, has explained: “Humans weren’t ‘built’ for anything but we certainly evolved to run barefoot. We have been running for millions of years and shoes were only invented relatively recently – probably in the last 40,000 years.” To put this in historical context, this means shoes were probably invented roughly around the time that Neanderthals became extinct and our ancestors created the world’s oldest cave paintings in Altamira, northern Spain. 

Even so, back in 490 BCE, when Pheidippides made one of the most remarkable runs in history, racing 25-26 miles from the Marathon battlefield to report Greece’s victory over the Persian invaders to the citizens of Athens – he did so barefoot. Mission accomplished, this famous ‘hemerodromos’ (as ‘day long runners’ who served in the Greek army were known) collapsed and died. Given that, in his final days, Pheidippides had run around 153m (246km) between Athens, Sparta and Marathon, it is unlikely that trainers would have saved his life. Runners in Greece’s ancient Olympics also competed barefoot: at the 328 BCE games, after Aegeas won the longest race - the dolichos, which covered around 2.2m (3.5km) – he ran home 62m (100km) to give his family the good news. (In case you were wondering, the present official length of a marathon – 26 miles and 385 yards – is reputed to be the result of a bit of jiggery pokery by British officials at the 1908 Olympics. They were so determined to ensure the race, which started at Windsor Castle, finished in front of the royal box at London’s White City stadium, they added 385 yards to the distance.)

 

 

Ethiopia's Abebe Bikila wins the Mexico 1968 Olympic Marathon in two hours, 12 minutes, and 11.2 seconds. 

 

Such exalted precedents – reinforced by Bikila’s Olympian feat –prompted Christopher McDougall, to challenge the growing cult surrounding the trainer in his 2011 bestseller Born To Run. Some experts agreed with McDougall that the increasingly elaborate footwear developed by brands such as Adidas and Nike actually interfered with humans’ natural stride and could cause injuries, whereas others argued the exact opposite, insisting these shoes minimise injuries, stabilise the foot and improve performance. 

For many runners, Lieberman suggests, this is a false dichotomy: “How one runs is probably more important than what is on one’s feet but what is on one’s feet can affect how one runs.” In his view, barefoot vs shoe are really just different ways of running. The research on which method is more effective may be exhaustive but it is hardly conclusive. Indeed, the only clear, consistent finding to emerge from studies is that developing a good running form/method - and sticking to it – is better than suddenly changing styles. If you’re an enthusiast, rather than a professional athlete, the best option is to choose the style you feel comfortable with.

“In general, barefoot runners land on the ball of the foot before letting down the heel - this is called a forefront or midfoot strike. They also tend to take shorter strides, have less of an overstride, and a higher step rate (about 180 a minute) but there is a lot of variation, depending on skill, speed, surface and other factors,” says Liebermann. As a rule of thumb, running barefoot is kinder on the knees, requires stronger calf muscles but is tougher on the Achilles tendon.

Until the 1970s, in Liebermann’s view, trainers were designed to be as unobtrusive as possible, an aid to barefoot running rather than an attempt to make athletes alter the way they ran. That began to change in the early 1980s with the launch of Nike’s Pegasus, followed, much later, by the development of Asics’ Nimbus and Hoka’s Clifton. 

These models constitute a kind of prequel to the race to build the ultimate running shoe or, as we now call it, the super shoe. In 2004, Adidas asked its legendary Japanese designer Toshiako Omori to create a revolutionary new trainer. Omori approached his task with a similar reverence for the foot as Leonardo, working with moulds, known as ‘lasts’, to create what he termed a ‘microfit’. In 2008, the first Adizero Pro was unveiled at the Berlin marathon. The night before the race, Ethiopian runner Haile Gebreselassie tried out the new shoes by sprinting down the hotel corridor. The next day, he broke the world record by 29 seconds with a finishing time of two hours, three minutes and 59 seconds. The new record was significant in its own right but, even more profoundly, it raised expectations, suggesting that a male athlete would soon do something truly remarkable and run a marathon in less than two hours. If you were working in research and development at Adidas or Nike at the time, this quest was a career-defining equivalent of the race to put a man on the moon.

So what exactly is a super shoe? Most of this new breed of trainer boast some kind of ultralight, hyper-responsive compressible foam in the middle of the sole designed to cushion the shoe and return more energy to the runner and a carbon fibre plate which acts almost like a lever, propelling the heel up and the foot forward with every toe push, boosting each step without the runner having to expend more energy.  (The conspicuous exception is the Adizero Adios Pro Evo 1 which uses carbon rods instead of a plate for the same purpose.) Every part of the shoe, from the thickness and composition of the midsole to how stiff the plate is and where it is located, is reconfigured by designers which means that each shoe interacts with our stride in very different ways. Extensive tests over several months by three experts for Outside magazine found that the two features which affected their stride most were how soft or firm the midsole is and the shape and placing of the toe rocker. 

Their findings underline the importance of picking a shoe that suits an individual’s running style. Although the Adizero Adios Pro got glowing reviews, one expert with narrow feet felt unstable running in it. Similarly, a stride runner (they increase speed by taking longer strides compared to cadence runners who also extend their stride but take more steps) complained that the Asics Metaspeed Edge + felt flat and didn’t generate any extra forward momentum. while another said it suited her tendency to run with the back of her foot. 

This latter running style, known as ‘heel-striking’, is criticised by McDougall in his book Born To Run as raising the risk of injury. This claim has been much disputed since, with some accusing the author of oversimplifying the issue and ignoring the impact of such forces as posture, calf tension and over-striding. The current consensus is that, unless you are a professional marathon runner, you should probably adopt whatever style gets you through the race.

No runner has officially broken the two-hour barrier yet, but many within the sport suspect this is only a matter of time. (Indeed, Kipchoge has run 1 hour 59 minutes and 40 seconds, albeit an unofficial event.) Last October in Chicago, another Kenyan, Kelvin Kiptum, ran the marathon in 2 hours and 35 seconds, 35 seconds faster than the previous official world record (set by Kipchoge at the same meeting in 2022). He was wearing Nike’s Alphafly 3 shoes and, like Assefa, set a new world’s best in only his third marathon. Even more remarkably, Kiptum was only 23 then – most previous record holders were in their late twenties or even early thirties – which is why many pundits expect him to become the first athlete to run this historic time.

The women’s marathon has quickened dramatically too. When Assefa smashed the world record in Berlin last autumn, the top eight runners all finished inside two hours and 20 minutes, making it the fastest race in the history of the sport. In that run, the Ethiopian winner broke the record – two hours, 15 minutes and 25 seconds – Radcliffe had set back in 2002. No woman had run within a minute and a half of the British athlete’s time for 16 years. Just as some experts were beginning to wonder if Ratcliffe’s time was untouchable, Assefa proved, emphatically, that it wasn’t. 

Few spectacles excite administrators, broadcasters, sponsors and spectators quite as much as the successive breaking of world and Olympic records – and the greater the margin by which they are smashed the bigger the splash – but the super shoe’s success has not been universally welcomed. Former athlete Robert Johnson, who oversees the site LetsRun.com, likens their development to financial doping: “Running is not supposed to be about who has the best technology, it’s supposed to be about who pushes the hardest, has the most talent and trains the hardest.”

The new generation of trainers aren’t cheap either. Nike’s Alphafly 3 shoes are expected to cost around £230 ($285), still something of a bargain compared to £500 ($400) for Adidas’s Adizero Adios Pro Evo 1. These price tags help to explain why Mara Yamauchi, a former British Olympic marathon runner, maintains: “We no longer have fair competition.”

Kenya’s Tegla Loroupe, who held the women’s marathon world before Ratcliffe, was even more forthright, telling the BBC: “You can have a faster shoe [but] what about those who can’t afford it? For me, there’s no difference between having a faster shoe and doping.” That might sound extreme but the cost of the Adizero Adios Pro Evo 1 is equivalent to three weeks’ wages in Kenya and six months’ salary in Ethiopia, the countries which, over the past 20 years, have shared the men’s marathon record.

Even in wealthier nations, these prices could deter aspiring runners. As Geoffrey Burns, a University of Michigan researcher, observed: “The elite is the tip of the iceberg but the sport is built on competition up and down the board. Think of how this affects high school and college levels.” It could certainly deter youngsters who can’t afford the technology to emulate the likes of Assefa and Kiptum. Even those who have already reached the top of the sport may find themselves seriously disadvantaged: in 2020, Reebok even let some of their sponsored athletes wear Nike shoes to ensure they could still compete.

 

 

Runners test the new Alphafly at Nike HQ.

 

Every game needs its heroes. Icons such as Roger Federer, Lionel Messi and Tiger Woods have all attracted massive new global audiences to their sports and, through footage of their epoch-making exploits, amplified by the purple prose of electrified sports journalists, brought glamour to their chosen field. But in the age of the super shoe, will the way distance runners are discovered and developed change irrevocably? It is certainly possible that the endorsement of a big brand – and access to their superior, and expensive technology – may have as much influence on a young athlete’s career as their talent and determination.

 

 

Roadrunners compete in the second annual 'Adizero: Road to Records' at adidas HQ in Herzogenaurach, Germany.

 

The relationship between brands and the athletes that wore their wares used to be much more straightforward. As Phil Knight recalls in his entertaining biography Shoe Dog, in the early 1970s when he was trying to get Blue Ribbon, Nike’s precursor, off the ground, he was so desperate to land the first sports star endorsement he agreed to pay $10,000 to Romanian tennis ace Ilie Nastase, a gifted star who, by virtue of his Latin good looks and quirky charisma, became an unlikely housewives’ favourite. It sounds like small beer now – in an age when Cristiano Ronaldo (Nike) and basketball stars Stephen Curry (Under Armour), and Le Bron James (Nike) have deals worth more than $1bn over their professional lifetimes – but this was a serious gamble back in 1972.

When athletes reach the summit, they will always win lucrative sportswear deals, but matters are much less clear cut on their way up, especially in middle and long-distance running which, compared to basketball, football, the NFL and tennis, is a relatively niche sport. While the big brands would have to be willfully blind to ignore a hot new prospect from Ethiopia or Kenya, marketability also comes into it. 

And marketability is a complex judgement which could factor in some – or all – of the following: the size of an athlete’s home market; an assessment of their prospects; their profile (especially on social media); their persona (Adidas’s deal with Kanye West – or Ye as he is now known – was immensely lucrative initially but, after his anti-Semitic outbursts, contributed to a 70% drop in profits, leaving the company with £500m of Yeezy-branded stock it can’t sell) and the particular demographic group a brand is focusing on.

Even a sport with the immense global reach of football is not immune to such cold, commercial considerations. In the 200os, it was rumoured within the game that brands were cutting back on the number of defenders they sponsored – and how much they spent on them – on the grounds that they don’t ignite the masses in the same way as Cristiano Ronaldo, Lionel Messi and Kylian Mbappe. After all, you can almost hear the bean counters asking, who was the last defender to win the coveted Ballon d’Or (European Footballer of the Year) award? In fact, it was Fabio Cannavaro, back in 2006, captain of Italy’s World Cup-winning team that year. His triumph came 30 years after the last defender to be given this accolade: the great, late Franz Beckenbauer.

 

 

 

 

There is a risk – let’s not get unduly alarmist – that the roles of sportswear brands and talent scouts begin to blur. It is also possible that audiences, wondering whether it's the super shoes that are behind a seismic shift in running times rather than the athletes, lose interest in the sport. Could the rapid, relentless smashing of world records prove to be too much of a good thing? After all, eight out of the ten fastest times in the women’s marathon – and six out of the ten fastest in the men’s race – have been recorded since the start of 2022. 

The Economist magazine, with its customary credo of ‘let the market decide’ dismisses such concerns as “misplaced technophobia.” Arguing that “this is a long way from shoes that matter more than their runners,” the August publication casts super shoes as just one of many developments – such as smoother football pitches – that encourage the defining sporting narrative that humans are on an “upward trajectory, becoming stronger, faster and fitter.” The Economist’s correspondent does concede that some technological innovations in sport should be reined in – such as cricket bats so powerful they skew the game against bowlers and javelins which are so aerodynamic that spectators run the risk of getting speared  – but does not think super shoes should be restricted. 

In part, this stance rests on a basic mistake: the magazine reports that governing body the IAAF “insists that all such super shoes should be available to all athletes in order to be legal, so there is no risk of results being determined by a lack of access to the best equipment.” In practice, neither Adidas nor Nike has indicated that they plan to make enough super shoes for every runner to buy a pair (even if they could afford them). Besides, after intense lobbying by brands, the IAAF quietly dropped its insistence that trainers had to be on sale for four months before a race and now allows ‘development shoes’ to be worn in races providing they comply with regulations. 

What is clear is that these new trainers are already exerting a magnetic appeal on young, aspiring athletes. As American track and cross-country coach Hal Walter put it: “My runners want these shoes. Why wouldn’t they? They come with ‘independent tests’ purportedly showing up to a 4% increase in running performance. Plus, their flashy appearance exudes a glamorous appeal that runners rarely experience in their sport.” 

Many ambitious runners will interpret the promise of better performance as a guarantee that they will run faster. Unfortunately, studies by the International Journal of Sports Physiology and Performance and the British Journal of Sports Medicine, suggest that this isn’t necessarily so. Their research concluded that faster runners wearing them improved their times much more significantly – sometimes by twice as much – than slower runners. No one has yet come up with a convincing explanation for this discrepancy but the Economist may well have a point when it says runners still matter more than shoes, although athletes running in super shoes will have an inherent advantage when racing against competitors who aren’t.

The brands developing these super shoes insist that their high prices are not exploitative but reflect their need to recoup their hefty investments in research and development. (For the record, Adidas usually invests around seven per cent of revenue in R&D.) To be fair, these new super shoes do sound radically different from their predecessors (although most experts have reserved final judgement until they have examined them thoroughly which means literally tearing them to pieces and studying each component in a lab). While the Vaporfly 4% (named after the performance boost it is said to deliver compared to other trainers) pioneered the use of a full-length carbon fibre plate to reinforce the shoe, the Adizero Adios Pro Evo 1 uses full-length curved carbon rods to mirror the metatarsal bones in the foot, features energy-returning Lightstrike Pro foam and weighs just 138g (4.86oz). The overriding goal is to improve running economy (the amount of oxygen an athlete requires to cover a certain distance). To that end, Adidas tested hundreds of prototypes with varying lengths of rods, in varying positions and with varying degrees of stiffness.

So the manufacturers’ claims are justified – up to a point. As footwear engineer Dr Bodil Oudshoom puts it: “The price tag for these super shoes is caused by three things. The higher costs of making a super shoe  (expensive foams, carbon plates, ultra-light upper materials and the fact they are more labour intensive to make); the extensive spend on R&D, not just developing innovative new materials but the cost of their internal labs and commissioning studies from universities) and the fact that these shoes are quite exclusive, meaning they don’t sell as many, and investment costs have to be spread across fewer products, so they don’t achieve the same economies of scale.”

It is also true that, as British ultra-marathon athlete Damian Hall, co-founder of a group called The Green Runner, says, “the hefty price tag neatly fits the concept of making the product feel exclusive, special and desirable, thereby adding to the marketing noise around these super shoes.”

And yet these special, limited edition shoes do challenge one of the basic tenets that has underpinned the burgeoning popularity of trainers. (Just to give you an idea, Hall estimates  that, on average, a British teenager owns six pairs.) Back in 1992, Nike’s Phil Knight told Harvard Business Review: “We make sure the shoe has the same functionality whether it’s for Michael Jordan or Joe Public.” The only difference between the two shoes, he argued, would be the styling, particularly the colours. The basic proposition to buyers – that they could pretend to be Michael Jordan, aspire to be him or simply get a vicarious thrill out of owning shoes that had been designed for him – helped the Jordan brand generate £2.5bn a year in revenue by 2019. In the age of the Adizero Adios Pro Evo 1 and Alphafly 3 super shoe, unless you are reasonably well off and/or extremely well connected, that appeal is gone.

Believe it or not, the price is not the most controversial aspect of Adidas’s Adizero Pro Evo 1. Every box for the 521 pairs sold in September contained a note saying that they were designed for “one race - so one marathon – and familiarisation time”. In other words if, as Adidas hopes, you buy these super shoes believing they’ll help you set a new personal best – which, as Haruki Murakami notes in his classic book What I Talk About When I Talk About Running, is probably the overriding motivation for most runners – you will almost certainly need to purchase another pair if your first attempt fails. It’s a paradoxical move for a company aiming for carbon neutrality by 2050. No wonder Runners World asked: “Has Adidas created the most extravagant super shoe ever?”

To campaigners like Hall, this is the equivalent of not merely fiddling while Rome burns but running out into the streets to pour petrol on the flames. “The trainer industry already emits as much CO2 as the UK. Almost all trainers are made from fossil fuels and are non-recyclable, 90% end up in landfill and they can take up to 1,000 years to biodegrade. The Adizero Adios Pro Evo 1 is the ultimate in single-use madness.” Some brands, notably Allbirds, Hylo, Iceburg, On Running and VivoBarefoot are doing interesting things with recyclable materials such as mushrooms and sugarcane but, he adds, “they need to be durable, if they only last 300 miles, as most trainers do, we need another one soon, which leads to more CO2 emissions from production.”

Even Hall admits he can understand the appeal of record-breaking super shoes. “It’s exciting for fans but it’s tainted by greenwashing. There are no credible super shoes designed for trail running so it’s not a debate that affects me directly. Ethically, I couldn’t bring myself to run in them. For a company like Adidas to create a shoe for ‘one race plus familiarisation time’ is shockingly out of sync with the ecological emergency we face.” The question is how many runners will share Hall’s principles and sacrifice improved performance to save the planet?

 

 

TOP Kenya's Kelvin Kiptum collapses to the floor after winning the men's London Marathon in 2023. BOTTOM Tigist Assefa's hard work is recognised after winning the Berlin Marathon.

 

The Economist’s verdict on the super shoe controversy – “Assefa and Kiptum are astonishing athletes and we should marvel at their feats, not what’s on their feet” – is fair, but a bit facile, driven as much by word play as insight. That said, for good or ill (and quite possibly a bit of both), the magazine may well be right when it concludes “this is a genie that cannot be put back into the shoebox.” Unless, of course, we throw away the shoebox and all run barefoot like Abebe Bikila.