Have you ever wondered what becomes of your old sports shoes? We might wear them for a year, then throw them out or donate them.
Almost 24 billion pairs of shoes are made each year, with a mere 5 percent estimated to be recycled. Many shoes donated to charity are unwearable.
That means tonnes of sneakers and runners — along with sports and athleisure apparel — end up in landfill each year. It also means these markets have a sustainability problem.
Why sportswear lags on 'circular fashion'
As one of the key sectors responsible for resource use and carbon emissions, the fashion industry is under increasing pressure to transition from a linear take-make-waste system to a "circular" model, where products are used more, made to be recycled and constructed from safe and recycled or renewable resources.
And while the industry at large is making progress, sports and athleisure apparel present a significant challenge due to their dependence on fossil fuel-based materials and the sheer quantity of goods being produced.
It can also be difficult to repair and recycle these products because of complex materials and construction, and demands linked to high performance needs.
Footwear is particularly problematic. Unlike a basic T-shirt, which might consist of a single material such as 100 percent polyester, a sneaker or running shoe can be made of as many as 65 materials and components — many of which are bonded with adhesives, hindering disassembly for recycling.
Perceived hygiene concerns relating to clothing in close contact with the skin and sweat can also deter reuse. (While the resale market for barely used sneakers is vibrant, even the most sustainably conscious consumer might baulk at wearing a pair of older second-hand runners.)
The good news is that recent consultation conducted by both the Footwear Distributors and Retailers of America and researchers at MIT suggest the footwear industry seems committed to progressing towards a circular economy, spurred on by increasing government regulations and consumer expectations.
Yet anyone wishing to buy sustainable athletic shoes will be familiar with a market awash with confusing contradictions and a lack of consistency and transparency.
There are several changes which could be implemented to ensure meaningful progress towards circularity.
Material innovation needed
Sustainability challenges in sports and athleisure wear stem from reliance on fossil fuels and harmful chemicals for synthetic materials such as polyester, nylon, elastane, EVA, polyurethane and most rubbers.
High-tech clothing and footwear commonly combine multiple types of materials which complicates recycling. Even if recycled and recyclable products are created (such as those using only one type of material), the persistence of microfibre and microplastic pollution remains a significant concern.
A recent market survey shows that the majority of 'sustainable' shoes commonly incorporate organic materials such as cotton or recycled materials such as polyester, ocean plastic and plastic bottles. While many boast a reduced or offset carbon footprint, these claims often remain unsubstantiated. Regardless of material choice and emissions, these products rarely include repair or end-of-life solutions.
Encouragingly, industry targets to eliminate plastics entirely have driven investment into bio-based alternatives like mushroom leather, Pinatex (pineapple leather), cactus leather, etc. However, these material innovations are still developing, and the financial cost and potential compromise on performance often pose challenges to consumers and brands.
Use of these materials also increases the risk of greenwashing, as many bio leather products are still mixed and bonded with fossil-fuel based materials such as PU (polyurethane), undermining biodegradability, and again making separation and recycling impossible.
Embracing recycling, repair, refurbishment and remanufacture
Despite these challenges, an increasing emergence of takeback schemes suggests a desire and intention to recycle, refurbish and remanufacture.
However a lack of transparency on the effectiveness of these programs, and the failure of takeback schemes in other sectors, leaves one to wonder what will happen to these products. Nike's high profile Move to Zero refurbishment scheme, for example, was recently paused indefinitely, indicating viability issues.
Initiatives such as Nike Grind, Save Our Soles and FastFeetGrinded — where unused materials and end-of-life shoes are ground-up and made into products such as running tracks and playgrounds — provide one solution, however these options largely involve ‘downcycling', with limited or no options for future recycling.
Prolonging the life of products through care and repair is an important strategy to reduce landfill but performance requirements and complex construction mean the kinds of initiatives demonstrated by brands such as Patagonia is challenging with high-tech footwear.
Apart from a small number of emerging niche footwear brands that integrate takeback, recycling, repair and refurbishment into their business models, initiatives by market leading sportswear brands have so far been small-scale, experimental and short-lived.
Sustainability starts with design
Many agree that footwear reuse, repair, refurbishment and recyclability depends on the design phase, particularly designing for assembly and disassembly. This process incorporates principles like simplification of design, reduction and standardisation of parts and materials, glue-less joining, minimizing flexible components, and designing modular products.
Additive manufacturing (3-D printing) also holds significant potential for circular manufacturing by reducing waste, overproduction, supply chain and energy consumption while enabling the creation of parts for modular designs to facilitate reuse and repair.
However, implementing these changes requires a shift in business models and supporting infrastructure. Few, if any, market-leading sportswear brands own their own factories. So while hype around circular economy innovations is increasing, a lack of transparency about investment into end-of-life solutions means questions remain as to whether the facilities exist to deliver on these promises.
Collaboration and accountability are key
Despite progress, corporate secrecy and competitiveness persist, and intellectual property battles over sustainable innovations continue to hinder advancement. Achieving a truly circular system requires collaboration and agreement among brands and across various stakeholders, including suppliers, government, academia, and entrepreneurs.
Initiatives such as the recently established Footwear Collective and Seamless Clothing Stewardship Scheme are crucial for building a circular infrastructure that benefits all. However meaningful progress requires significant funding. Currently, most initiatives that involve tariffs and funding are voluntary.
Despite good intentions, the lack of a short-term return on investment into circular business models and infrastructure poses a significant challenge for corporations focused on shareholder interests, profits, and growth. Even industry itself is starting to recognise that costs and margins risk continuing to dictate progress, with government mandates providing a potential, if unpalatable, solution.
Yet there are many reasons for brands to engage willingly. Authentic participation in collective sustainability initiatives can generate stories consumers want to engage with and, which can, in turn, drive sales.
Consumers can play a pivotal role in this shift by choosing brands that support genuine change and consistently prioritise sustainability and transparency. A number of emerging resources such as Good on You and the Ethical Fashion Guide are available to help them do so.
Ultimately, industry, consumers and governments are all accountable for sportwear's sustainability problem, and collaboration will be the key to achieving meaningful progress.
Dr Alexandra Sherlock is a lecturer in the School of Fashion and Textiles with expertise in the study of footwear. In 2021 Alex founded the Footwear Research Network to support the ongoing development of academic enquiries into shoes and to enhance research impact and industry collaboration.
Dr Rebecca Van Amber is currently a Senior Lecturer in the school of Fashion and Textiles, and the program manager of the Bachelor of Fashion & Textiles (Sustainable Innovation). She is an expert in sustainability and circular economy, textile and apparel research and development, and textile properties.
