MATERIALS
Why polyester dominated for so long
Polyester is a plastic. It is polymerised from petroleum feedstocks, spun into filament using an antimony catalyst, and coloured with disperse dyes. The industry standardised on it between the 1970s and 1990s for reasons that had far more to do with the factory floor than with athletic performance.
Cost. Petroleum-derived polyester is cheap to produce at industrial scale and the process is highly automated. The raw input undercuts cotton fibre per kilogram.
Consistency. Synthetic filament is manufactured to exact specification, so every batch is essentially identical. Cotton varies by harvest, region and weather.
Manufacturing durability. Polyester does not shrink in production, holds dye reliably, ships without spoilage and survives cutting and sewing. These properties matter to factories more than to wearers.
Finish flexibility. Because it is a blank plastic surface, polyester takes almost any finish: water repellency, wicking treatments, texture. That made it easy to re-engineer for each new trend, and easy to bolt performance chemistry onto.
The athletic story (wicking, fast-drying, lightweight) was built after polyester was already the standard. The category did not choose the fibre for performance. It built performance claims around a choice already made on cost.
What is actually changing now
Several forces are converging.
Microplastic awareness. Every wash cycle sheds synthetic microfibres, because the fibre is plastic and abrasion breaks it down. Research linking synthetic clothing to microplastic pollution moved from academic literature into mainstream news through the late 2010s and into the 2020s. Most people buying activewear today know synthetic fabric sheds, and many actively avoid it.
Chemical exposure concerns. PFAS finishes, phthalate plasticisers, formaldehyde resins and disperse dyes moved from industry obscurity into public conversation. These are mostly added during processing, not inherent to the plastic, but they ride on synthetic activewear because that is where the performance finishes go. Searches for "non-toxic activewear" and "PFAS-free leggings" have climbed year on year.
Skin-health awareness. The wellness category trained people to read ingredient lists on food and cosmetics. Clothing is the next surface getting that scrutiny. Sensitive-skin and eczema populations were early and now drive a meaningful share of demand.
Regulatory pressure. The EU has been moving to restrict PFAS in textiles, with phase-ins running through the second half of the decade, and France and several US states have passed their own measures. As compliant brands strip PFAS out, one of polyester's engineered advantages (durable water-repellent and wicking finishes) gets harder to deliver.
Construction catching up. This is the underrated driver. Cotton did not get better at wicking. What changed is yarn and knit engineering. Core-spun yarn wraps a fine elastane core inside cotton fibre, and interlock knit structures hold shape, so modern cotton-elastane recovers and resists bagging in a way earlier cotton blends could not. The fabric engineering finally met the demand.
Scepticism about synthetic sustainability claims. "Recycled polyester" and "ocean plastic" have been progressively exposed as lower-carbon at best and marketing-heavy at worst. Recycled polyester has the same skin chemistry and sheds the same microplastics as virgin. Shoppers looking for genuinely cleaner activewear increasingly skip the synthetic route altogether.
Where the comeback is oversold
Honesty means naming the weak parts of the story, because plenty of natural-fibre marketing overreaches.
Natural fibre is not automatically clean. The word describes the plant, not the processing. Conventional cotton is one of the most pesticide-intensive crops, and cotton fabric can still be scoured with chlorine bleach, dyed with restricted azo dyes and finished with formaldehyde resins. A natural fibre with conventional wet processing is not clean activewear. The only thing that verifies the chemistry is a processing-chain audit such as GOTS, and most cotton activewear on the market does not carry one.
Cotton still loses on moisture. Cotton absorbs and holds water rather than moving it to the surface to evaporate. For studio, gym and walking that is a non-issue and arguably pleasant. For cold-weather outdoor cardio or very heavy sweat, it stays damp, and there polyester or merino genuinely outperforms it. Any claim that cotton wins everywhere is false.
Almost all of it still contains synthetic. The stretch in cotton "activewear" comes from elastane, which is a polyurethane spun from diisocyanates in a solvent such as dimethylformamide. There is nothing natural about it. The honest framing is a small, contained percentage, not a plastic-free garment.
What the shift looks like in the market
Five years ago, natural-fibre activewear was a small niche of yoga-adjacent brands selling pure-cotton lounge pieces, undersized and short on credible performance options. Today, multiple brands are launching organic-cotton activewear engineered for movement, established labels are adding natural-fibre lines, and consumer pressure has pushed certifications like GOTS and OEKO-TEX into wider (if still far from universal) use. The volume is still small next to polyester, but the growth curve is steep and the drivers are structural.
What this means for what you wear
More real options. Natural-fibre activewear that actually performs now exists across price points. The "natural means shapeless" reputation is outdated.
Read the label harder, not less. Wider certification uptake helps, but "natural" and "eco" on a hangtag still carry no standard. A named certificate with a searchable number is the signal that means something.
A genuine but bounded performance case. For indoor and mixed training, modern cotton-elastane closes most of the gap. The places synthetic still wins (cold-weather outdoor cardio, swimwear, technical outdoor gear) are narrower than a category built entirely around polyester would suggest, but they are real.
Where LAINE HILL sits
We built LAINE HILL to engineer organic cotton activewear for the training most women actually do: yoga, pilates, gym, walking, indoor cardio, daily movement. The category was full of polyester and short on natural-fibre options that held up at that level.
The fabric is 92% organic cotton with 8% elastane, knit at roughly 240 GSM in an interlock structure with core-spun construction. That construction language is the engineering answer to "make cotton activewear that does not sag at the knees by month two". We are not claiming it is plastic-free, the 8% elastane is synthetic and we say so, and we are not the right choice for cold-weather outdoor cardio or swimwear. We are the practical choice for daily indoor training, and we would rather tell you exactly where that boundary is than pretend it does not exist.
The market is moving in this direction. We are building for where it is going, without overselling how far it has already gone.
Common questions
Why is cotton activewear coming back?
Several drivers at once. Microplastic shedding from synthetic fabric moved from research papers into mainstream attention over the past decade. Chemical-exposure awareness (PFAS finishes, phthalates, disperse dyes) grew alongside it. Sensitive-skin and eczema populations went looking for cleaner options. And construction improved: core-spun cotton-elastane yarns and interlock knits closed most of the fit and recovery gap that made earlier cotton activewear sag. Cotton did not suddenly get better at wicking. The reasons to tolerate polyester got weaker.
Is natural fibre activewear a trend or a long-term shift?
Structural rather than cyclical. The drivers (microplastic awareness, chemical sensitivity, regulatory pressure on PFAS and phthalates, scepticism about synthetic sustainability claims) are not fashion cycles. That said, natural fibre is still a small share of a category that is overwhelmingly polyester by volume, so "returning" describes a direction, not a finished change.
Does natural fibre activewear perform as well as polyester?
For most indoor and mixed training, close enough that the difference is marketing more than function. Modern cotton-elastane matches polyester on stretch and recovery and beats it on softness and skin compatibility. It loses clearly on one thing: drying speed. Cotton holds moisture, so for cold-weather outdoor cardio or heavy sweat sessions, polyester or merino still has a real edge. Anyone claiming cotton wins everywhere is overselling.
Is natural fibre automatically cleaner than synthetic?
Not automatically. The fibre being natural says nothing about how it was bleached, dyed and finished, which is where most flagged chemistry enters fabric. Conventional cotton is grown with heavy pesticide use and can be finished with chlorine bleach and formaldehyde resins. "Natural fibre" is a good start, not a finish line. Only a processing-chain audit such as GOTS verifies the chemistry, and most cotton activewear on the market is not GOTS-certified.
