Changes to materials and construction are crucial in creating shoes that will provide athletes with performance gains. What this means for sustainability strategies is a  separate question.

Sports shoe brands’ seriousness about sustainability is impossible to deny. Many of them have announced ambitious targets for tackling climate change and publish annual sustainability reports to track progress.

Japanese brand ASICS has published a pledge to reduce carbon emissions from its direct operations and from its supply chain by 63% by 2030, taking the figures for 2015 as the baseline. The company also has the target of achieving net-zero carbon emissions by 2050. Puma has set itself a target of a 35% reduction in “absolute emissions” (the total amount emitted) from its own entities between 2017 and 2030, and a 60% relative emission reduction (emissions relative to specific activities) for its supply chain between 2017 and 2030.

At New Balance, the aim is to reduce scope-one and scope-two emissions by 60% by 2030, with figures for 2019 as the starting point. Scope one refers to direct emissions from the company’s own facilities, while scope two means indirect emissions from the energy the company consumes. For scope three, which includes emissions from suppliers, the target is a reduction of 50% by 2030.

Nike’s figures are more graphic. It has calculated that it has the same climate impact as a major city. If it includes the people who work in its supplier factories, more than a million people are involved in making Nike shoes and other products. The company said its emissions at the start of this decade were 11.7 million tonnes of carbon dioxide equivalent (CO2e) per year. According to academic modelling platform the Global Gridded Model of Carbon Footprint, these figures would rank Nike in a similar bracket to Munich, Prague or Amsterdam. Its aim is to reduce, by 2030, its scope-one and scope-two emissions by 65%, its scope-three emissions by 30%, and to reach net zero by 2050.

Compared to 2017 figures, adidas has a target of reducing the emissions for each of its products by 15% by 2025. By 2030, its aim is to have reduced absolute emissions across its entire value chain by 30%. It, too, targets becoming climate-neutral by 2050.

Where the buzz is

All of this is good work and the pride these companies have in their progress so far comes across clearly in press releases and other communications. Even so, it is hard to miss that the biggest buzz of all for brands still seems to be related to performance. If the gains that athletes make in speed, height or distance owe anything to their shoes, the footwear brands concerned are certain to celebrate loudly. This is especially true in the build-up to an Olympic Games.

The global director of athlete services at adidas, Fabian Schweizer, has said that while professional athletes are looking closely at advances in biometric monitoring and in nutrition to help them improve their performance, good footwear remains critical to their success.

Writing on social media platform LinkedIn at the start of this Olympic year, Fabian Schweizer picked out his three top innovation trends in sports performance for 2024. He said that biometric monitoring to inform personalised training programmes was certainly one of them. He explained that targeted training programmes, based on data from wearable technology and sensors, were becoming increasingly important to athletes and coaches.

In a similar way, he said personalised nutrition and the field of nutrigenomics, which studies the interaction between nutrition and a person’s genetic profile, are also becoming increasingly important for professional athletes. An increase in available data is allowing sports people to address accurately their own specific nutritional needs.

If these first two trends are concepts that most athletes of previous generations barely thought about, the third trend that Fabian Schweizer has identified is as old as sporting competition itself. He said that footwear remains a critical component in professional sport. In terms of performance enhancement, he said the most important innovations are aimed at delivering customisation, energy return, and biomechanical optimisation.

Forefoot rocker

Last year’s big headline-grabbers in athletics included Ethiopia’s Tigist Assefa, who broke the world record for women for the marathon in Berlin in September with a time of 2:11:53. In her post-race reaction, the athlete held up one of the shoes she wore, an Adizero Adios Pro Evo 1, as though to pay tribute to its contribution.

Speaking at the launch of the shoe earlier the same month, Ms Assefa said: “These are the lightest racing shoes I have ever worn and the feeling of running in them is an incredible experience, like nothing I’ve felt before. They enable me to put my full focus on the race, which is exactly what you want as an athlete. I can’t wait to lace up at the start-line in these.”

Each Adizero Adios Pro Evo 1 shoe weighs 138 grammes, which is 40% lighter than any previous running shoe the brand has created. It incorporates a forefoot rocker component “to trigger forward momentum”. The shoe also contains a new version of a proprietary foam material called Lightstrike Pro. A non-compression moulding process makes the foam lighter, while delivering greater energy return, adidas claims. New outsole technology, a mesh upper and the removal of the sock-lining are other weight-saving measures. 

From triumph to tragedy

A month after Tigist Assefa’s record-breaking performance in Berlin, Kenyan runner Kelvin Kiptum set a new world record for the men’s marathon, clocking a time of 2:00:35 in Chicago. He was wearing a prototype pair of Nike Alphafly 3 running shoes for the event. His success sparked widespread speculation that here was an athlete who was on course to achieve a sub-two-hour time in race conditions and would do so soon, perhaps even on the greatest stage of all, at the Paris 2024 Olympics this August. Triumph turned to tragedy for Kelvin Kiptum at the start of this Olympic year, however, when he died in a road accident. He was 24.

Features in the Alphafly 3 include a high-stack proprietary foam called ZoomX for lightweight cushioning. It has a continuous bottom, connecting the heel and the forefoot. Nike says this suits varying foot-strike patterns and provides “a smoother heel-to-toe transition”, regardless of the runner’s pace. The shoe also contains a wider, full-length carbon fibre plate for “a propulsive, stable ride”.

The current Olympic men’s marathon champion, Eliud Kipchoge, also from Kenya, has already run the race’s distance, just over 42 kilometres, in less than two hours. He did so at a specially organised event in Vienna in 2019, at which he was the only competitor, with pace-setters moving in and out at certain stages to help drive him on. He, too, wore shoes from Nike at this event and achieved a time of 1:59:40. The official records only recognise times athletes achieve in official competitive events. Nike says Eliud Kipchoge has given input to the design of a number of running shoes down the years, including its Free, Pegasus, Vaporfly and now Alphafly ranges.

Dual trend

It is no coincidence that shoes for marathon runners receive particularly intense attention from the designers of performance shoes. Changes to the design of a shoe may only shave a tiny amount of time or effort off each step an athlete takes, but if an elite marathon runner takes 150 or 160 steps per minute, it can make a real difference over the course of a race. This is always at the forefront of the efforts of shoe designers who work at this level. 

Performance gains are not their only objective, because comfort and injury prevention are also important, but a cursory glance and a brief feel of an old shoe should be enough to show how much thinner and lighter today’s footwear is. On the face of it, the enthusiasm footwear performance advances generate could be at odds with companies’ commitments to sustainability, not least because it is entirely possible that elite athletes will wear each pair only once before throwing them away. Fabian Schweizer has argued that innovative materials, including recycled and bio-based options, are gaining traction as athletes and manufacturers alike recognise the importance of reducing their  environmental impact. He says the industry is now witnessing “a dual trend of sustainability and high-end performance enhancement”, as though the two can go hand in hand.

Strike a balance

A senior executive specialising in sustainability at New Balance, Katy O’Brien, says performance and sustainability can work together. She says the company she works for remains committed to creating premium, performance-driven shoes. She believes the buzz that advances in footwear performance can create is a good thing for brands and for the industry in general, but she insists that it is possible to strike a balance between performance improvements and brands’ battle to reduce waste and lower the environmental footprint of their products.

In contrast to the short lifespan of what she refers to as “the supershoes” that elite athletes race in, she says keeping and wearing footwear for a long time is an increasingly important part of this battle. In the course of her 20 years as a running enthusiast, she has absorbed the received wisdom that if you start to feel some pain in the knees, it is time to change your shoes, or that if you have already run a lifespan total of around 500 kilometres in the same footwear, it is time for a new pair. Now, however, she believes many runners are pushing beyond the pain and the previously accepted distance limits in a bid to make the useful life of a pair of  shoes longer and in doing so make their carbon footprint smaller.

She has worn some of the supershoes and understands why athletes and designers are so captivated by the benefits they offer. Her assessment of them from a sustainability point of view is that the foams, carbon-plates and other materials in their construction make it difficult to recover much of their value at the end of their short life. “But it is a very small proportion, perhaps 1%, of all footwear,” Ms O’Brien insists. 

If these elite shoes last for, at most, a marathon or two, the athletes who wear them can try to make sure their other footwear, the shoes they wear when not competing, are longer-lasting. Another benefit Katy O’Brien identifies is that the desire to emulate, if not replicate, progress in performance in more mainstream shoes is leading to changes that will provide a sustainability bonus. She mentions some of the reductions in material use that deliver the all-important weight-savings at the front end and says they can also improve the recyclability of the product.

“There is so much we can do to reduce waste,” she explains, “and the time has certainly come for us to stop talking about what might be possible and to start making meaningful change at scale.” Returning to New Balance’s target of achieving a 50% reduction in its scope-three emissions by 2030, Ms O’Brien has calculated that if the company could eliminate material waste, this would take care of 12% of the total, almost a quarter of the way to the goal. 

Innovations in the Adizero Adios Pro Evo 1 include a forefoot rocker to trigger forward momentum.
Credit: ADIDAS

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