2023 – Tigst Assefa

24-Sep-2023 – Berlin Marathon – 2:11:53 – Adidas AdiZero Adios Pro Evo 1
Date of birth: 3-Dec-1996
Nationality: Ethiopian
World Record duration: 4 months, 8 days (as of 1 February 2024)

The athlete:               
Tigst Assefa stunned the world when she won the 2022 Berlin Marathon in 2:15:37, having come from seemingly nowhere to become one of the fastest distance runners in history. Many commented on how it represented an almost impossible improvement of 18 minutes over her debut at the Riyadh Marathon earlier that year. There is much more to this story before we even get to her heroics at the 2023 Berlin Marathon.

Beginning her career with the 400 and 800 metre disciplines, Assefa showed considerable promise, winning or finishing on the podium in many of her races. It would eventually lead to her competing in the 800 metres at the 2016 Summer Olympics, but she would begin suffering increasingly from issues with her achilles tendons. Aggravated by running and training in track spikes, she would run no races at all in 2017 and was told by doctors to stop running track events if she wanted to avoid even more significant injuries.

This was when Assefa and her coach made the decision to switch to road events. In 2018 she would debut in the 10 kilometre distance, rapidly improving her times as she adapted to the rigours of road running. Valencia would host her half-marathon debut in 2019. She finished fifth in 68:24, which given that her ongoing achilles impacted the race made her run deeply impressive. Assefa saw doctors soon afterwards, who bluntly told her to switch professions.

Returning to Ethiopia on crutches, over the next six months Assefa focussed on her rehabilitation. During this time, the world plunged into the midst of one of the worst pandemics in living memory, Assefa having limited opportunities to train and none at all to race. She was in need of money, and was offered an appearance fee for the upcoming 2022 Riyadh Marathon. It was her first race since 2019, she was out of shape by the standards expected by elite athletes. Her finishing time reflected the gulf she still had to cross to reach the levels of competitiveness she enjoyed in short distances.

Winning her next two races, both half-marathon distance, Assefa had reason to be confident despite the times being several minutes behind the half-marathon world record at the time. Continuing with her training and rehabilitation, she would pit herself against the marathon distance once more in Berlin, which arguably was her real debut. There would still be challenges ahead.

Achilles tendonitis would force Assefa to withdraw from the 2023 London Marathon in April of that year, illustrating that her battle with injuries continued nearly a decade after they began. By September, she was ready to take on the Berlin Marathon again, the city greeting her with conditions perfect for distance running.

Storming away from the start, there was a large lead pack that stuck with Assefa, all slowly beginning to creep further and further under the world record time set by Brigid Kosgei in 2019. Many assumed that like Peres Jepchirchir in the 2022 Chicago Marathon, the pace would begin dropping considerably after halfway.

Assefa continued to accelerate.

With the gap growing ever bigger, the question was by how much she would set the world record. By this stage her only company was pacer Azmera Gebru and the clock. She would finish with a negative split, 1:06:20 for the first half and 1:05:33 for the second. On crossing the line, she would take off her highly publicised Adidas Adios Pro Evo 1 racing shoes, kissing one of them in front of cameras. Thanks to Philipp Pley of the Running Shoe Geeks group on Facebook for photos of Assefa’s actual shoes in the Adidas Berlin store following the race.

Both her splits during the race beat her previous best for the half-marathon, noting again that her focus was on the full marathon distance. In an interesting analysis by ultramarathon legend Camille Herron, it was pointed out that the difference between Assefa’s time and the men’s world record was 8.138%. When Paula Radcliffe set the new women’s world record at the 2003 London Marathon, the gap was reduced to 7.753%.

Following Assefa’s win, many commentators have suggested something untoward regarding her performance. It should be noted that similar allegations were levelled at Brigid Kosgei following her world record performance. No evidence has been provided from any source to support these claims, and no formal allegations have been made. It should be noted that having won the 2022 Berlin Marathon, as a major international athletics event, Assefa would have been subject to greater scrutiny regarding such matters.

Although the question has not been studied in-depth, there is the suggestion that some athletes may respond better to the technology of modern distance running racing shoes than others. It should be noted that while there are many highly talented athletes competing against Eliud Kipchoge, few have been able to replicate his times on the track. Another interesting article suggests that women’s distance running in Kenya and Ethiopia is seeing increasing interest, with younger athletes becoming involved. The landscape is without question changing yet again.

The shoes:                   

Almost as remarkable as Assefa were the stark white Adidas shoes on her feet. To give them their full name, the AdiZero Adios Pro Evo 1 is one of the most significant shoes to have released since the Nike VaporFly series that launched in 2017. In an article you can read more about here, Adidas had previously pursued lightness with the AdiZero Sub2. Unlike the Nike VaporFly, it followed the formula of traditional racing flats. Adidas would eventually shift their focus, coming up with something distinctly different from Nike.

These were carbon-fibre rods, designed to anatomically follow the shape of the bones in the human foot. Although Nike and its star Eliud Kipchoge kept breaking world records, athletes in the AdiZero Adios Pro series began racking up wins at some of the biggest marathons in the world.

What they still lacked was the lightness of the VaporFly, and over the last two years were working on something truly special to bridge that gap. Weighing in at 138 grams, the AdiZero Adios Pro Evo 1 weighs less than the AdiZero Sub2, and massively undercuts the Nike VaporFly as well. The geometry also shifted to become even more aggressive, to make the most of the carbon-fibre energy rods within.

Much has been said about its durability, or lack thereof. Designed to last one marathon, it recalls when Nike tried this concept with the Mayfly. Using foam with expanded air pockets to reduce weight, it only just beat the far more modern Adidas at 135 grams. It was designed to only last 100 kilometres, which is still about double the AdiZero Adios Pro Evo 1. Unlike the Adidas however, it did not end up pushing the performance envelope past its conventional competitors.

What it was however was cheap at US$45 and recyclable, with Nike encouraging owners to send their Mayflys back to be recycled into rubber athletic courts and tracks. It is unclear whether the AdiZero Adios Pro Evo 1 is similarly recyclable, however Adidas have received considerable criticism on this issue.

The Lightstrike Pro foam is made out of Thermoplastic Polyester Elastomer, which was further enhanced for the AdiZero Adios Pro Evo 1, saving an additional 50 grams over the AdiZero Pro 3. Another 70 grams is saved through the outsole, almost impossibly minimalist. Then there is the matter of price, which is considerably higher than anything else on the market at US$500. Furthermore, only 521 pairs are being released worldwide. Although my understanding was that this was initially to comply with World Athletics rules regarding availability, I have since learned that there are dispensations for prototypes. The limited availability was simply another marketing strategy.

Nike released the Zoom VaporFly Elite in 2017 leading up to the Berlin Marathon for approximately US$600, with apparently only 99 pairs available online in addition to those available in the Nike shop in Berlin. Then there was the stunning Zoom VaporFly Elite Flyknit of 2018, which reduced the already svelte 168 gram weight by a further 11 grams, releasing for the London Marathon in similarly even more limited numbers for around US$675. Another colourway was released in early 2019, however few details are available other than few pairs made it out into the wild.

It should be noted that Nike also released these shoes because it could, not due to any rulebook, and this technology became widely available through the ‘regular’ VaporFly series. While the limited availability of the AdiZero Adios Pro 1 Evo this has caused some uproar, Adidas plan to release more pairs later this year.

In my view, the AdiZero Adios Pro 1 Evo represents the first homologation special in modern athletic footwear, certainly for distance running. Such specials have regularly featured in motorsports, where manufacturers have created limited runs of fire-breathing monsters with little relation to the cars they were based on.

It is the nature of innovation, which has been a constant theme in distance running since the days where one could set the marathon world record barefoot. Further limits may be imposed in the future, but for the moment Adidas has found the outer limits of these rules. It is up to its competitors to literally and figuratively step up.

Philipp Pley via email
Steven Tse via Facebook