Microplastics and Your Workout: What We Know So Far

A few years ago, "microplastics" was a word you'd hear in articles about turtles. Now it's a word you'll see in medical journals — and increasingly, in conversations about the clothes we sweat in.

We're not here to scare anyone. We're here because this is one of the reasons Sweat Bibs exists, and we think it's worth understanding.

What Microplastics Actually Are

Microplastics are tiny fragments of plastic — under five millimetres, often invisible — that come from the breakdown of larger plastic items, or from things shedding plastic fibres directly. Synthetic clothing is one of the bigger sources. Every wash of a polyester shirt, every drag of a nylon short across your skin, releases small amounts of plastic into the environment and, increasingly we're learning, into us.

What Researchers Are Finding

The science is still developing, but the trend in the research is one-directional. Microplastics have been detected in human blood, in lung tissue, in placentas, and in stool samples from people across the world. There is active investigation into what this means for inflammation, hormone disruption, fertility, and long-term health. Nothing is fully settled, but very little of what's emerging is reassuring.

We say this carefully because we don't want to overstate. The honest position is: we don't yet know the full impact. We do know enough to choose differently where we can.

Why Workout Clothes Are a Particular Concern

Most activewear is made of synthetics. That's the first issue. The second is what we do in it.

When you train, your body heats up. Your pores open. You sweat heavily, and that sweat sits between your skin and the fabric. Friction is constant — kicks, punches, twists, drags across mats. The conditions for fibre shedding are about as ideal as you can get. And then everything goes in the wash, where another round of fibre release happens.

Combat sports turn this dial up further. We sweat harder than most. We grapple, clinch, roll. Our gear takes a beating, and we wear it close.

What Sweat Bibs Does About It

The whole brand is built around this answer.

We use natural fibres — cotton, organic cotton, hemp, linen — because they don't shed plastic. They shed cotton, which is fine. Where we use a small amount of elastane in our Muay Thai shorts, it's the minimum needed for range of motion, and we're transparent about it.

We embroider our logos rather than printing them, because most printed logos on clothing are plastic-based.

We pack everything in a cassava-based biodegradable bag instead of a polybag. Even the swing tags are plastic-free.

None of this makes us heroes. It just makes us consistent.

What You Can Do, Independent of Us

Even if you never buy a single thing from Sweat Bibs, here's what we'd suggest:

• Check the labels of your training gear. If it's 100% polyester or nylon, especially for pieces that sit close to the skin, that's where the highest exposure tends to be.
  
• Wash synthetic gear in a microfibre-catching laundry bag. It won't fix the wearing-it part, but it reduces what goes into waterways.
  
• Wherever you have a natural-fibre option that genuinely performs, take it. Cotton t-shirts. Hemp blends. Linen Blends.
  
• Don't buy more than you need. The most sustainable garment is the one you already own.

The Honest Bottom Line

The research on microplastics in the body is incomplete. The research on microplastics being *in* the body is not. We'd rather train in something that doesn't add to that load if we can help it. That's the whole pitch — no panic, just a different choice.