World records have been tumbling. There has been debate as to why, with one overriding more newsworthy factor - the rise of the supershoe. Of course less travel, more training and less stresses from the lack of competition due to the pandemic.  The shoe itself does not break records but it helps. The innovative supershoe Nike Vaporflys was the first and inspired a wave of competitor responses, which the delay of the Tokyo Olympics has helped come to market.

2017 was box office for carbon plate shoes with the Breaking 2 project when Eluid Kipchoge ran in the first generation Nike Vaporfly - featuring a full-length, spoon-curved carbon plate and for a race shoe and an immense amount of foam.  Shoes with carbon plates had launched as far back as 1991, but it was the Nike Vaporfly that was the innovative game changer. For the following  two years, Vaporflys were a source of controversy about fairness and technology in sport, mainly because no one else had them. Helped by the delay of the Tokyo 2020 Olympics the competition has arrived: nearly every major running shoe company has a carbon-plate shoe on the market in 2021. The good news for us is that they’re no longer aimed only at would-be Olympic marathoners.

An idea before it's time

Brooks

The revolution has been simmering for a long time before exploding.  As far back as the 1980s, shoe companies were experimenting with the unique combination of strength and light weight offered by carbon fibre. Around 1989, Brooks launched a pair of shoes – the Fusion and had a carbon-fibre plate sandwiched between the midsole and outsole that functioned as a propulsion system.

Fila also produced racing shoes with carbon-fibre plates in the 1990s.

Adidas had the next big leap working with scientists at the University of Calgary’s famed Human Performance Lab, a young mechanical engineer  Darren Stefanyshyn developed a curved plate design that improved running economy by an average of one per cent. Adidas called it the ProPlate and used it into some of their shoes in the early 2000s apparently used by Ethiopian great Haile Gebrselassie to set a world marathon record in 2007. An idea before it's time the concept of a marginal improvement in running economy never really captured the public’s imagination, and the shoe was  quietly scrapped.

Nike research and development for the 4% and Sub2 attempt

Then Nike came to the party and how with their new shoe in 2017 featuring a full-length, spoon curved carbon plate and thick ZoomX foam. They didn't go the usual press release route hyping the Vaporfly’s groundbreaking features, in-house testing results, and listing the gold medalists already wearing it. Instead, Nike took a high stakes bet: announcing that three star runners would attempt to run a marathon exhibition race in under two hours, helped by the new Vaporfly. Given that the world record at the time was nearly three minutes slower than the sub-two goal, it was seen as a lose-lose scenario for Nike: if the race flopped, it would prove the Vaporfly was no good; if it succeeded, it would prove the shoe was cheating. You know how the story goes , in May 2017, the reigning Olympic champion, Eliud Kipchoge, raced to an amazing (but unofficial) 2:00:25 at the Breaking2 race at a Formula One track in Monza, Italy. Critics immediately called for the shoe to be banned. Problem was no one could agree on what exactly the plate in the shoe was doing and it should be banned.

The research on the Adidas ProPlate, had suggested that the carbon-fibre plate kept your big toe joint straighter during toe-off, saving energy that would otherwise be wasted in bending the joint, but the at the cost of putting additional strain on the ankle joint. Nike’s Vaporfly design team introduced a curve to the plate, which seemed to reduce the extra load on the ankle. The plate’s origins was clear, making it hard to argue that Nike’s shoe was breaking the rules in a way that the previous plate-equipped shoes from Adidas, Fila, Brooks hadn’t.

The plate was only part of the story. Previous marathon racing shoes have gone with minimal cushioning, the Vaporfly sat on a chunky 31-mm-thick ZoomX foam midsole .All running-shoe midsoles provide cushioning & a spring effect. They compress when you land, and spring back as your foot takes off, giving a little jolt of free energy. Most midsoles useEVA, which typically springs back with at most 65 per cent of the energy you put into them. Adidas’s groundbreaking Boost midsoles, which use a thermoplastic elastomer called TPU, got 75.9 per cent. The ZoomX foam, which is made from another thermoplastic elastomer called polyether block amide (PEBA), returned 87 per cent. ZoomX is more resilient & way lighter than EVA, which is why the Vaporfly can have such a thick midsole without becoming unreasonably heavy. The thick midsole allows it to store more energy with each footstrike, like having a bigger battery in your shoe, and the higher resilience gives you more of that energy back. A benefit of the carbon plate may be that it keeps the unusually thick and soft midsole stable,The overall result of combining the plate and the foam is that Nike’s original Vaporfly, according to testing ,improves your running economy by an astonishing four per cent on average compared to the next-best racing shoes.

Looking at the other running shoe companies first response to the Vaporfly:

Brooks

It wasn't understood why the combination of plate and foam works so well, which is one of the reasons it has taken so long for rival companies to launch competing shoes. Elite runners from almost every company have been racing in unreleased prototypes for several years now. For example, Des Linden won Boston Marathon way back in April 2018 in an early prototype of Brooks’ Hyperion Elite; the shoe, featuring a carbon-fibre plate embedded in a thick layer of the company’s DNA ZERO foam. The goal of the plate is to stabilize the foam and provide a snappy feel and propulsion at toe-off.

Eliud Kipchoge crossing the finish line at the INEOS 1:59 Challenge and breaking two hours over 42.2K. Photo: INEOS 1:59

Saucony

Each company has their own take Saucony’s Endorphin Pro carbon-fibre plate plays two roles: spreading the force of the heel’s landing impact out into a ultralight, resilient foam made from the same type of material as Nike’s ZoomX; and rolling your foot forward while keeping the toe joint straight.

Under Armour’s HOVR Machina , a carbon composite plate is designed to “make the transition off the forefoot feel snappier.”

New Balance’s FuelCell TC, again featuring a carbon-fibre plate and a new ultra-resilient foam, aims to provide a “combination of energy return and protection from eccentric loading” in runs lasting longer than an hour.

Protection from eccentric loading could turn out to be the make-or-break feature for the whole category of shoes. Eccentric loading is the braking action of your leg muscles each time your foot hits the ground, and it inflicts muscle damage that slows you down and leaves you sore. A lot of people who’ve raced in these shoes say, ‘I couldn’t believe I woke up the next morning and my body didn’t ache, and I could get up and go for a run again.

In October 2019, Eliud Kipchoge was successful at breaking the two-hour barrier in an exhibition race in Vienna, clocking 1:59:40.2. His shoes were even thicker and raised eyebrows yet again.The AlphaFly, has three different carbon-fibre plates and multiple layers of foam. Just when it seemed that the playing field was levelling out, the AlphaFly had raised fears that Nike athletes will once again be a few steps ahead of the pack at the 2020 Olympics – just as in 2016, when athletes wearing disguised prototypes of the -unreleased Vaporfly won the women’s Olympic marathon and swept the podium in the men’s race. The delay of Tokyo 2020 has meant that the chasing pack are catching up, so events should be a lot fairer.

The governing body for track and field, World Athletics, had deemed that a shoe can only have foam of a maximum of 40mm must be on general release for three months, hence Asics' recent release & hyping of the MetaspeedSky. Although, things may be about to change, with World Athletics walking back on this decision, announcing in December 2020 that in any events athletes can wear prototype shoes and promptly, Kenyan Kibiwott Kandie became the first man to run under 58 minutes for the half marathon in the Adidas Adizero Adios Pro, breaking the previous record by 30 seconds. In additon,  Mo Farah and Sifan Hassan also broke the men’s and women’s one-hour records wearing Nike shoes in Brussels in September 2020. The prototypes would still have to abide by its current rules and could be cut up if there were any suspicions.

With the Olympics on the horizon, it is certainly going to be an interesting year in running!

Inspired by an article at runningmagazine.ca June 2020 -’The carbon shoe revolution’