Best natural fabrics for activewear, compared honestly

If you are stepping back from polyester, the next question is, what then?

There are real natural alternatives. Each of them does some things well, and some things poorly. None of them are perfect. The brands selling them sometimes overstate the upside and quietly skip the downside.

This is the honest version, fabric by fabric. What it does on the body during a workout. What it does in the wash. Where it falls short. Which one we ended up choosing for LAINE HILL, and why. If you want the full reasoning behind that choice, it lives in why we got activewear wrong.

Organic cotton

What it does well. Organic cotton breathes. It absorbs sweat into the fibre instead of letting it pool against your skin. It is soft from the first wear and stays soft through years of washing. It does not become a bacterial environment the way synthetics do, which is why a worn cotton t-shirt smells like sweat, not like sour milk.

It is also the gentlest fibre we know of for sensitive skin. GOTS certification means the cotton is grown without synthetic pesticides and processed without the worst of the textile chemicals, which is what actually irritates most people's skin during workouts. The skin side of that is in why your sportswear makes you itch.

Where it falls short. Cotton dries slowly. For high-cardio outdoor training in cold weather, that matters. It stretches and recovers poorly on its own, pure cotton activewear bags out at the knees within a session. It also wrinkles, although that does not really apply to a sports legging.

Verdict. The strongest all-rounder for low-to-moderate impact training. Yoga, pilates, light running, gym work, walking. Pair it with a small percentage of spandex and the stretch problem goes away.

Merino wool

What it does well. Merino is the closest thing nature has to a technical fabric. It thermoregulates, keeps you warm when it is cold and cool when it is warm. It wicks moisture away from the skin and dries fairly fast. It is naturally antibacterial, which means a merino base layer can go three or four wears before it starts to smell.

It is also surprisingly fine and soft. The diameter of the fibre is what makes the difference between scratchy wool and merino, the finer the fibre, the softer the feel.

Where it falls short. Merino is expensive, usually three to four times the price of cotton, sometimes more. It pills under friction, especially in high-wear areas like waistbands and seat seams. It snags easily. It is not vegan. And it requires careful washing, most merino activewear cannot be machine-dried.

Verdict. Excellent for outdoor sport, hiking, running, and travel where odour-control matters. Less practical for daily indoor training because of the cost and the durability trade-off.

Tencel / Lyocell

What it does well. Tencel is wood pulp dissolved in a closed-loop solvent and extruded as fibre. The closed-loop part is real, over 99% of the solvent is recovered and reused. The fibre itself is silky-smooth, drapes well, manages moisture better than cotton, and has a cool feel against the skin that makes it strong for hot studio environments.

Where it falls short. Tencel is technically a regenerated cellulose fibre, it is not a fully natural fibre in the way cotton or wool are. The process is cleaner than viscose, but it still requires industrial chemistry. The fabric is also less durable than cotton, it pills and weakens over time. Some "tencel" garments on the market contain only a small percentage of true Tencel-brand lyocell, with the rest being conventional viscose or polyester. Read the composition tag.

Verdict. A genuine option, especially as a small percentage in a blend. Not as gentle on durability as cotton.

Bamboo viscose

What it does well. Bamboo as a plant grows fast and needs minimal water. The fibre, when properly made, is soft and drapes beautifully.

Where it falls short. This is where greenwashing happens most. Most bamboo fabric is technically rayon, the plant is dissolved in carbon disulphide and sodium hydroxide, two industrial chemicals, and extruded as fibre. The process is harmful to factory workers and to the environment when not properly contained. Bamboo lyocell, which uses the closed-loop process similar to tencel, is cleaner. But it is rare, expensive, and almost never what is being sold as "bamboo activewear" at scale. We say more about claims like this in we are not perfect.

Verdict. The bamboo plant itself is renewable. The fabric labelled bamboo is usually not what shoppers think it is. We chose not to use it.

Hemp

What it does well. Hemp is one of the most environmentally efficient fibres on the planet. It grows fast, needs almost no water, improves the soil it is grown in, and the fibre itself is exceptionally durable. It is naturally antibacterial and breathable.

Where it falls short. Hemp is rough. It softens with washing, but it never reaches cotton-soft. It does not stretch. The supply chain is small, which means consistent quality is hard to source. Pure hemp activewear feels closer to canvas than to performance fabric.

Verdict. Strong as a small component in a blend, especially for outdoor or layering pieces. Not yet practical for next-to-skin activewear at scale.

Modal

What it does well. Modal is another regenerated cellulose fibre, made from beech wood. It is soft, drapes well, and resists shrinking better than cotton.

Where it falls short. Modal is closer to viscose than to cotton in how it is made. It is not a natural fibre, it is a wood-derived fibre that goes through chemical processing. As activewear, it does not breathe particularly well, and the moisture management is unremarkable.

Verdict. Better as a loungewear fabric than as an activewear fabric. Not where we wanted to land.

Linen blend

What it does well. Linen is one of the most breathable natural fibres in the world. In hot weather, a linen blend stays dramatically cooler than a cotton garment of the same weight. The fibre is also very durable.

Where it falls short. Linen does not stretch. It wrinkles aggressively. Pure linen is too stiff for activewear, and most linen blends used in activewear are mostly cotton with a small linen percentage, which is fine, just not what the marketing suggests.

Verdict. A good warm-weather option as a small percentage in a blend. Not the foundation fabric for a sportswear brand.

What we chose, and why

We tested cotton, modal, tencel, and bamboo lyocell as the dominant fibre in early prototypes.

Cotton with 8% spandex won.

It won on softness, first-wear soft, hundredth-wash soft. It won on breathability across both warm and cool conditions. It won on the sensitive-skin test we ran with sample wearers. It won on price-to-quality ratio at scale, which matters because we want to make this affordable to actually wear, not just affordable to make.

It is not the most technical fibre we tested. Merino moves moisture better. Tencel feels cooler in a hot studio. Hemp is more environmentally efficient. For the direct head-to-head against the fibre it replaces, see cotton vs polyester for fitness.

It is the most balanced fibre across the things that matter most for daily training, feel on the skin, breathability, durability, honesty about composition, and price you can actually justify.

Eight percent spandex is not "no synthetic." It is the minimum we found we needed to give the legging the stretch and recovery a workout demands. We are transparent about the percentage. We are not trying to hide it inside a "100% natural" claim that would not be honest.

That is the choice. We will keep testing as new fibres become viable. If something better comes along, we will use it. For now, 92% GOTS-certified organic cotton, 8% spandex, no greenwashing.

LAINE HILL

Continue reading

• Cotton vs polyester for fitness, eight criteria, scored honestly, head to head.
• What to wear for what, best fabrics by sport, yoga, pilates, strength, running, hot yoga, and more.
• Why two leggings with the same composition feel different, yarn, knit, finishing, and what "premium" actually means.