Walk into almost any activewear brand's "sustainability" page and you'll find one of two materials doing most of the talking: organic cotton or recycled polyester. Both get marketed as the responsible choice. They're not interchangeable, and neither one is automatically the better option. Here's what each material actually does, and where the trade-offs are.

What recycled polyester actually is

Recycled polyester, often labeled rPET, is made by breaking down existing plastic (usually water bottles or polyester waste) and re-spinning it into new fiber. It diverts plastic from landfill, which is a real benefit. But it's still a synthetic, petroleum-derived material at its core. Recycling it doesn't change what it's made of or how it behaves once it's a garment.

Two things worth knowing:

• It still sheds microplastics. Washing and wearing synthetic fabric releases tiny plastic fibers into water systems, regardless of whether the polyester started as new or recycled.
• It can't be recycled indefinitely. Each time polyester is reprocessed, the fiber quality degrades. Most rPET is a one-time diversion from landfill, not a closed loop.

What organic cotton actually is

Organic cotton is grown without synthetic pesticides or fertilizers, and under GOTS certification, processed without the harsh chemical treatments used on conventional cotton. It's a natural, biodegradable fiber, which means it doesn't carry the microplastic shedding problem synthetic fabrics do.

The trade-offs run the other way:

• It uses more water to grow than synthetic fiber production, though organic farming practices typically use meaningfully less than conventional cotton.
• It doesn't stretch or wick moisture the same way synthetics do, which is why most performance-focused organic cotton is blended or engineered with construction techniques (like specific knits) to compensate.

So which one is actually better?

It depends on what you're optimizing for. If the priority is diverting plastic waste, recycled polyester does that. If the priority is what's touching your skin, how the fabric breaks down at end of life, and avoiding ongoing microplastic shedding, organic cotton has the advantage.

At Tender, we lean toward organic cotton and other plant-derived materials for that reason. It's not that synthetic fiber is never the right call. Our Cardio line uses Microtencel, a wood pulp-derived fiber, specifically for the stretch and moisture management that organic cotton alone can't deliver. The point isn't "natural good, synthetic bad." It's choosing the material that's honest about what it does, and telling you which one you're wearing.

The short version

Recycled polyester solves a waste problem. Organic cotton solves a skin and biodegradability problem. Most "sustainable" activewear picks one and markets it as the whole answer. We'd rather tell you what each material is actually good at, and let you decide what matters most to you.

Want the full breakdown of what's in each Tender piece? Visit Our Materials.