The part nobody mentions

You're sitting in plastic. In a ninety-degree room.

Three times a week, soaked through, pressed against the one part of your body that has to stay cool. Heat is half of what's working against your fertility. The other half is what you're wearing in it.

Amuro is the sauna short with no plastic against your skin — and a cooling insert where it counts.

No payment, no card, no spam. We'll email you the sauna test results and the launch date. Unsubscribe any time — how we handle your email.

Inside a dark timber sauna, the door open onto dune grass, sand and the sea beyond.

The study this starts from

Ten men. Three months. Twice a week.

Ten men with normal sperm counts took two Finnish sauna sessions a week — fifteen minutes each, at 80–90°C — for three months.

Sperm count and motility both fell significantly. Three months after they stopped, the measures were still below where they started. At six months, they had returned to normal.

Garolla et al., "Seminal and molecular evidence that sauna exposure affects human spermatogenesis," Human Reproduction 28(4), 2013, pp. 877–885. Read it on PubMed

It is ten men. That's a small study and we're not going to pretend otherwise — we'd rather you knew the size than found it out yourself. It's also a study of saunas, not of this garment. Nothing on this page is a test of anything we've made.

Every other claim here about heat, fabric and sperm comes from published third-party research, listed in full at the foot of this page. Amuro is clothing, not a medical device.

The problem

Wearing synthetic shorts in a sauna

It traps the heat in

Your testicles work best around 2–4°C below core body temperature. Wet synthetic pinned to the skin holds warmth against the one area that needs to shed it.

It blocks your only cooling system

Your body sheds heat there by sweating and by moving away from the torso. Soaked polyester stops the first of those working at all.

It's plastic, against skin, at 90°C

Polyester is PET — the same family as a drinks bottle. Nylon and elastane are plastics too. Most swim and gym shorts are a thin plastic weave.

The heat raises the temperature. The wet synthetic stops it leaving. The worst hour in your week is the one you set aside for your health.

What we made

Two layers of natural fibre, and a cool spot that stays cool

Waffle-knit cotton outer shell

A natural fibre, not the polyester most sauna shorts are made from. The waffle structure holds the fabric off itself so air and moisture keep moving through, instead of collapsing into a wet sheet against you.

100% plant-based lyocell liner

The layer actually touching you. Spandex-free. No blend, no percentage points of plastic hidden in it.

The air gap between them is the mechanism

Not a feature. It's the difference between a soaked layer pinned to your skin and one that keeps moving and dries.

A hidden pouch, and fabric always in between

The insert sits over the one area that needs it, with fabric between it and you at all times — so the safety rule isn't something to remember, it's built in.

Zero synthetic against your skin. No polyester, no nylon, no elastane in the liner.
The only elastane is in the waistband — covered, and it does not contact skin.
OEKO-TEX Standard 100 certificate number published before any order ships. We're not printing a licence number before it's issued.

The waffle shell on this first run is conventional cotton, not organic. I wanted to say organic and I can't, so I'm not going to. Certified organic waffle is what I'm chasing for the second run.

Close-up of a dark charcoal waffle-knit fabric, showing the raised cell structure. — Waffle structure, magnified — this is what the outer shell's construction looks like. It is not a photograph of our fabric. Our own material photography goes up when the first samples arrive.

A small dark timber sauna at the edge of a lake, below a steep green hillside.

The insert

A thermostat, not an ice cube

A gel pack or a bag of ice has one melt point — 0°C — and warms continuously from there. In a 90°C room that happens fast. So the curve you get is: far too cold at the start, roughly right for a short window, then useless. And frozen anything against bare skin risks a cold burn.

A phase-change material behaves differently. It absorbs heat while holding at a set temperature as it thaws. Steady cool, for the session, rather than a slide from too cold to nothing.

We haven't published a temperature figure yet, and we're not going to invent one. Published cooling-vest numbers would flatter us — but those tests use large vests in 35–45°C conditions, and our insert is small and going into a room twice that hot. We're measuring it ourselves, in a real sauna. The number will be minutes, not hours. It goes up before any order ships, whatever it says.

Straight talk

What we're not claiming

This is the part most brands leave out. It's how you should judge us.

It's clothing, not medicine

Amuro is not a medical device, not a fertility treatment, and not a cure for anything. We're not telling you it will improve your count. We're telling you it keeps one area cooler in a hot room and puts no plastic on your skin.

No reviews, because we haven't launched

No influencers, no seeded testimonials, no invented five stars. There are people on the early-bird list and that's a real number we'll show you. The day someone earns a review, it goes up here.

The best argument against us

If you can happily give up the sauna while you're trying, do that. It's free and it works. We exist for the men who won't or can't — and for the second input, which quitting never touched anyway.

And get a semen analysis. It costs little, it replaces guessing with a number, and it's better than anything on this page. If you have a real concern, see a doctor.

Who's behind this

I noticed what everyone was wearing

I'm Ruairi. I'm 21, based in Northern Ireland, working full-time with university alongside it. I started lifting in December 2023 and became a sauna regular — the electric one at my local leisure centre, a wood-fired one in a garden in County Tyrone, and now the one at my gym in Belfast. Nearly three years, several times a week.

After enough sessions I noticed something that bothered me: everyone in there, me included, was sitting in plastic swim shorts. Soaked, clinging, in a ninety-degree room. It was obviously the wrong material for the room, and nobody made the right one.

I'm not a doctor and I'm not a fertility expert, and I'd be suspicious of me if I claimed to be either. What I am is someone who's been in the room a long time, noticed what everybody's wearing, and decided to do something about it.

Ask me something, or tell me I've got something wrong — hello@amurolife.com. There are a hundred pairs in this run. There is no support desk.

Or watch it being made — @amuro.life on Instagram, @amurolife on TikTok.

First run · 100 pairs

Keep the ritual. Fix the inputs.

Join the early-bird list. No payment, no card, no spam — we'll email you the sauna test results, the OEKO-TEX certificate number, and the launch date before anything goes on sale.

Early-bird pricing held for the first run. You'll hear from us when there's something real to say. Unsubscribe any time — how we handle your email.