Some runs seem to leave a mark. The ones you take on wet sand, for example, leave a temporary trail that the water erases a moment later. Others, however, leave something invisible but lasting: microscopic fragments of plastic. That technical t-shirt that wicks away sweat before you even think about it, those light, almost ethereal shorts, and those shoes that feel like wings on your feet. Everything is incredibly efficient, lightweight, and high-performance. Everything, or almost everything, is made of plastic. It’s the silent trail of every stride, every breath, and every impact. No guilt, but maybe some questions.
The Hidden Side of Efficiency
Here’s the runner’s paradox: We run in the open air (hopefully), we enjoy nature or the city as it wakes up, and meanwhile, our performance-driven gear wraps us in a synthetic embrace.
The technical clothing you wear, the water bottle you hold in your hand, your shoes—all these objects were designed to accompany you on your run. But in certain cases, without you knowing it, they release something unexpected into the world. The synthetic fibers in the fabrics break down, the soles wear away, leaving particles in the air and water, and plastic containers slowly degrade. And every single particle, every micro-residue, becomes part of the environment—and sometimes, part of your own body.
Technical fibers have replaced cotton, shoes have become carbon exoskeletons, and water bottles are getting lighter but are often synthetic. In short, we run to get healthier, but we equip ourselves with materials that, when looked at closely, are anything but “light” in their impact.
It’s a paradox that’s hard to notice: We take care of our bodies while—unintentionally—contributing to the spread of microplastics in the environment. And when the environment sends them back, in the form of particles suspended in the air, water, or food, it’s always our bodies that receive them.
Don’t get me wrong, this isn’t a crusade against progress. Synthetic fibers have revolutionized the way we run, making clothes breathable, lightweight, and durable. They’ve allowed us to push boundaries and make the running experience more comfortable in all weather conditions. The problem, if anything, is that this comfort comes with an invisible cost, a price that the planet, and in a certain way, we ourselves, are beginning to pay.
Microplastics: The Invisible Ghosts
Every time you wash that super-technical shirt, millions of tiny synthetic fibers break off and end up in the drain. From there, it’s a short trip to rivers, lakes, and eventually the sea. And it’s not just washing. Simple wear and tear, the friction during a run, also causes particles to detach from shoe soles, ending up in the environment.
What are microplastics? They are plastic particles smaller than 5 mm. They can be “primary” (i.e., produced directly in microscopic form, such as in cosmetics or technical fabrics) or “secondary” (the result of the degradation of larger plastic materials). A polyester t-shirt, for example, can release tens of thousands of fibers with every wash. But even a run on a hot day can contribute to their release into the air due to sweat aggression or a backpack rubbing against fabrics.
And then there are shoes. The sole, often made of EVA, TPU, or synthetic rubber, is one of the main sources of mechanical release of microplastics. Every foot strike, every push-off, every kilometer leaves a trail. Invisible, but real. The 2021 London Marathon estimated that participants collectively produced about 11 tons of microplastics from shoe use alone.
These microplastics are the ghosts of our consumption, too small to be filtered by water treatment plants and too resilient to disappear on their own. They end up in the food chain, from the fish we eat to the water we drink. And yes, they can even be inhaled. The body that moves, the very body we try to make stronger and healthier with every stride, absorbs and releases these invisible fragments, almost without realizing it.
The Race Toward Sustainability
So, what should we do? Go back to running naked or in clothes made of raw wool? Not exactly. The good news is that the industry is taking its first, albeit clumsy, steps toward more sustainable alternatives. They’re looking for recycled materials, often sourced from post-consumer plastic bottles, to create new fibers. Then there are natural fabrics like Tencel (a fiber derived from wood pulp) or merino wool, which offer breathability and heat management with a lower environmental impact. Some brands are experimenting with soles made from more biodegradable or recycled materials.
None of these is a perfect solution, and the journey is still long, but it’s a start. Awareness is the first step. Choosing garments that last longer, that are made with recycled or natural materials, and maybe washing them with special bags that retain microplastics, can make a difference.
For their part, many companies are increasingly sensitive to the issue, in part because they perceive that their own customers are as well. Yet, the problem is always the same: the “sustainable” alternative often costs more, performs less well, or is less available. But most importantly: it’s not enough for a single item to be “green” if everything else around it continues to operate according to the old rules.
Perhaps the point isn’t to look for the perfect product, but to change the way we think about our gear. Reduce the number of items, wash them less frequently and at low temperatures, choose durable materials, and dispose of them correctly. This is also a form of training: less visible, more mental, but with concrete effects.
Running is a simple act, but within that simplicity hide many choices. Every time you lace up your shoes, you’re choosing what to put between yourself and the world. And today more than ever, that “between” carries weight.