Activewear fabric matters more than you think. Most people judge activewear by how it looks or feels — but rarely stop to ask: what is this actually made of? From plastic-based synthetics to water-wasting natural fibers, every fabric tells a story. Some are breathable, biodegradable, and skin-safe. Others are quietly polluting our air, water, and bodies.

The question “is polyester bad for you?” is one of the most searched topics in activewear today — and the answer is more complicated than most brands want you to believe. Polyester is in over 90% of the workout clothes on the market. It’s cheap to produce, easy to manufacture, and performs reasonably well in the short term. But the long-term cost — to your skin, your hormones, and the environment — is significant.

At EveryRep, we believe education leads to better choices — so here’s a breakdown of the most common activewear fabrics, what they’re made of, and why it matters.

The Fabrics: What’s Really in Your Workout Clothes

Polyester

Polyester is the most widely used fabric in activewear — and one of the most problematic for your health. Made from plastic and petroleum, it’s one of the cheapest and most commonly used synthetic fibers in the world. Its production involves chemicals like formaldehyde, PFOAs, and PFCs — all toxic to humans and wildlife.

Polyester sheds microplastics every time it’s worn or washed. These microplastics enter waterways, food chains, and eventually our bodies. The fabric is non-breathable and creates an environment where odor-causing bacteria thrive — which is why polyester gym clothes tend to smell worse than natural alternatives, even after washing.

Perhaps most concerning: research has linked chemicals in polyester activewear — including BPA and PFAS — to endocrine disruption. During exercise, when your pores are open and sweat is flowing, these chemicals can migrate through the skin and into your body. Testing has found BPA levels up to 40 times the safe exposure limit in major-brand sports bras and leggings.

Polyamide

Another plastic-based fabric, polyamide is often made from petroleum or coal. It’s highly energy-intensive to produce, with a major toll on the environment and human health. Like polyester, it sheds microplastics that end up in fish, birds, drinking water — and eventually, us. Polyamide takes hundreds of years to decompose while releasing toxic gases and greenhouse emissions throughout that process.

Traditional Nylon

A synthetic fiber made from petrochemicals and crude oil, traditional nylon is non-breathable and poor at absorbing moisture. It’s non-biodegradable — persisting in the environment indefinitely and contributing to long-term microplastic pollution. For a detailed comparison of nylon vs polyester in leggings and compression wear, see our BioLuxe™ technical analysis.

Rayon

Rayon is a semi-synthetic fiber made from wood pulp. While its source material is natural, the manufacturing process requires heavy chemical processing to convert cellulose into wearable fiber. Production often uses carbon disulfide, a neurotoxic chemical that can impact workers, surrounding communities, and ecosystems.

Viscose (including Bamboo Viscose)

Viscose is derived from plant-based sources like bamboo or wood pulp. However, the manufacturing process is chemically intensive and damaging to both workers and the environment. It requires high water and energy usage, and has been rated D or E for sustainability by global benchmarking standards. While bamboo itself grows sustainably, the process of converting it to fabric undermines many of those environmental benefits.

Conventional Cotton

Often considered “natural,” cotton is far from clean. It uses 6% of the world’s pesticides and 16% of all insecticides — more than any other crop. Cotton production harms soil, pollutes water, and contributes to greenhouse gas emissions. It’s also extremely water-intensive: it takes over 700 gallons of water to make a single cotton T-shirt.

From a performance standpoint, cotton absorbs moisture and holds it against your skin rather than wicking it away. This makes it a poor choice for high-intensity training, where true moisture-wicking performance is essential for comfort and thermoregulation.

So What Should You Wear Instead?

Not all fabrics carry these risks. A new generation of plant-based and responsibly engineered materials is proving that activewear can deliver real performance without the toxic tradeoffs.

TENCEL™ Modal

TENCEL™ Modal is a plant-based, biodegradable fabric made from sustainably harvested beechwood, processed in a closed-loop system that recovers over 95% of solvents. It’s naturally soft, breathable, and moisture-wicking — not through chemical surface finishes that wash out, but through the fiber’s inherent hydrophilic structure.

TENCEL™ Modal is certified under OEKO-TEX® Standard 100, meaning the entire fabric has been independently tested for over 100 harmful substances including BPA, PFAS, formaldehyde, and heavy metals. It’s also biodegradable, breaking down in months rather than the centuries polyester requires.

At EveryRep, we use TENCEL™ Modal Active across our product line — from T-shirts and tank tops to sports bras and underwear. Every product carries our BodySafe Guarantee — zero polyester, zero polyamide, and only biodegradable CiCLO® nylon where compression demands it.

BioLuxe™ Nylon (with CiCLO® Technology)

For compression-grade products where maximum stretch and recovery are required, our BioLuxe™ fabric incorporates CiCLO® biodegradable nylon. Unlike traditional nylon, CiCLO®-treated fiber is engineered to biodegrade in landfill and ocean environments at rates comparable to natural fibers — while maintaining full performance during its usable life.

How the Fabrics Compare: Side by Side

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Choosing the Right Fabric for Your Body and Lifestyle

When choosing activewear fabric, don’t just focus on price or style. Pay attention to how it breathes, how it’s made, and how long it lasts — both in your wardrobe and in the environment. A well-made garment should support your training and your values.

Your clothes are in constant contact with your body — especially during training, when skin absorption is at its highest. The fabric you choose determines whether that contact is helping you or quietly working against you.

Ready to make the switch? Explore our full collection of non-toxic, plastic-free activewear — built for performance, engineered for your health.