ACTIVEWEAR
For half a century we have been told synthetics are the best thing for sports and outerwear. The whole activewear industry was built around that idea.
It wasn't always this way. Before polyester, sportswear was made from natural fibres, cotton, wool, linen, down. The clothes were heavier. They were bulkier. They were more expensive to make, because real fibre is more expensive than melted plastic spun into thread.
Polyester opened a door. It was cheap, durable, light, and it dried fast. It spread through the industry like wildfire. Polypropylene. Nylon. Spandex blends. Recycled PET. Every gym in the world dressed itself in plastic.
We are still wearing it.
This is what we know about that now.
What polyester actually does during a workout
It traps heat. The fibres do not breathe the way cotton breathes. Sweat pools instead of releasing, which is why your back stays wet for an hour after class.
It traps bacteria. The same lack of airflow that traps moisture creates the perfect environment for the bacteria that cause smell. This is why synthetic activewear starts to stink within a few wears, and why it does not always wash out. We get into the chemistry of that in why polyester smells faster.
It sheds microplastics. Every wear and every wash releases tiny synthetic fibres into the air, into the water, and onto your skin. "Recycled" polyester does not solve this, recycling the source does not change what the fibre is made of. The longer take on that is in is recycled polyester actually sustainable.
It can move chemicals into your skin. A 2023 study from the University of Birmingham found that sweat increases the leaching of brominated flame-retardant chemicals from microplastics into the skin, exactly the kind of skin exposure that happens during a workout, when pores are open and absorption is elevated. Earlier work by Giovanna Luongo at Stockholm University identified thousands of textile chemicals detectable in finished garments, many of which persist even after repeated washing.
None of this is fatal. None of it is alarmist. It is also not what we want pressed against our skin for hours, three or four times a week, for the rest of our lives. If you have been wondering why your sports bra band leaves an itchy red patch, the science behind that is in why your sportswear makes you itch.
Why we built something different
We are not trying to save the world. We are trying to set a higher standard for what gets sold as activewear.
The brief was simple. Make the cleanest possible activewear that still works during a workout. Soft enough to wear all day. Strong enough to survive a squat. Honest about what is in it.
What we ended up with: 92% organic cotton, 8% spandex.
We are going to walk through both, what they are, why they are there, and what we deliberately chose not to use. If you want the broader comparison across every natural fibre on the market, that lives in best natural fabrics for activewear.
Why cotton
Cotton breathes. It releases heat instead of holding it. It absorbs sweat into the fibre instead of letting it pool against your skin. It feels soft, even after a hundred washes, because the fibre itself is soft, not chemically softened to feel that way.
Cotton also does not become a bacterial environment the way polyester does. The sweat goes into the fibre and dries from the inside out. That is why a cotton t-shirt smells like sweat, while a polyester shirt smells like sour milk. A 2014 study by Callewaert et al. in Applied and Environmental Microbiology confirmed the difference, polyester samples carried significantly higher concentrations of odour-producing bacteria after a single workout session.
There is a reason cotton was the standard before polyester arrived, and there is a reason it is coming back as more women move away from synthetics. For the head-to-head, see cotton vs polyester for fitness.
Why organic cotton, specifically
Conventional cotton is one of the most chemically intensive crops on the planet. It is sprayed with pesticides, herbicides, and fungicides during growth. It is processed with bleaches, dyes, and finishing chemicals afterwards. Some of those chemicals stay in the finished garment. Most leach into the water, soil, and air around the farms.
Organic cotton is grown without synthetic pesticides, herbicides, or fertilisers. The seeds are non-GMO. The processing chain uses fewer chemicals, and when it is GOTS certified, those chemicals are audited.
The difference matters for the people who grow and process the cotton. It matters for the soil. It matters for what is actually in the fabric that touches your skin for hours during a workout. We unpack what GOTS audits and what it does not in what GOTS, OEKO-TEX and Fair Wear actually mean.
Why 8% spandex
Spandex is synthetic. It is, technically, a form of plastic. We are not going to pretend otherwise.
It is also the reason a sports legging stays where you put it. Without spandex, the legging does not stretch with you, does not recover after a squat, does not stay around your waist. It becomes loungewear that happens to be cotton.
We chose 8%, not 12, not 18, because that is the minimum we found we needed to get full performance out of the rest of the fabric. Below 8%, the recovery dropped. Above 8%, we were adding plastic for no real return. Why two leggings with the same percentage on the tag can feel completely different has a longer answer in why two leggings with the same composition feel different.
Eight percent spandex is not "no synthetic." It is a deliberate, transparent compromise. We are not hiding it. We are explaining it.
What we deliberately did not use
Polyester. Even recycled polyester. Recycled or not, it is still plastic. Still sheds microfibres. Still traps heat.
Nylon. Same problem.
Polypropylene. Worse.
Bamboo viscose marketed as "natural." Most bamboo fabric is rayon, bamboo cellulose dissolved in an industrial chemical bath, then extruded as fibre. The plant is renewable. The process is not clean.
We tested cotton blends with modal, with tencel, with nylon. Cotton with 8% spandex won on softness, on breathability, on honest sourcing, and on the squat test.
What this means for what you put on
You are not going to make every choice perfectly. We do not, either. Sportswear is still consumption. It is still a product. It is still processed. We get into the honest version of that in we are not perfect.
But the gap between "polyester everything" and "92% organic cotton with a transparent stretch component" is real. It shows up in how it feels. It shows up in how it smells. It shows up in what touches your skin for the eight hours a week you are training.
We are not asking you to throw out the rest of your wardrobe. We are saying that the next time you replace something, you have a real alternative. One that is honest about what it is made of.
That is the standard we are trying to set.
LAINE HILL
Continue reading
- Best natural fabrics for activewear, compared honestly, cotton, merino, tencel, bamboo, hemp, modal, linen side by side.
- Why your sportswear makes you itch, the chemistry behind skin reactions to synthetic fabric during workouts.
- We are not perfect, what we do, what we deliberately do not claim, and how we read greenwashing.
Common questions
Is cotton good for sports?
Yes, for low to moderate impact training. Cotton is breathable, soft against the skin, and absorbs sweat without trapping bacteria the way polyester does. With a small percentage of spandex it also stretches enough to move with your body. For high-cardio outdoor training in cold weather, the trade-off is slower drying time.
Why is polyester bad for sportswear?
Polyester traps heat and bacteria, which is why synthetic activewear smells faster than cotton. It also sheds microplastics during wear and washing, and research from the University of Birmingham found that sweat draws hazardous chemicals out of synthetic fibres into the skin. None of this is fatal, it is also not what we want pressed against our skin for hours at a time.
Why does LAINE HILL use 8% spandex?
Because without it, a sports legging would not move with your body the way it has to. Spandex at 8% is the minimum we needed for the fit and recovery a workout demands. It is synthetic, we are not pretending otherwise. We chose to be transparent about the percentage rather than hide behind a 'natural' label that would not be honest.
What does organic cotton actually mean?
Organic cotton is grown without synthetic pesticides, herbicides, or fertilisers. The seeds are non-GMO. The processing chain, from spinning to dyeing, uses fewer chemicals than conventional cotton. Look for GOTS certification: it audits both the agricultural and the textile-processing side, which most other 'organic' labels do not.