Non-Toxic Gym Clothes For Men
You sweat into it for an hour a day, four or five days a week, for years. Nothing else you own gets that kind of contact time.
So it is worth knowing what it is made from, what was done to it, and which part of it is actually touching you.
The liner is the part that matters
Shorts are sold on the shell fabric, because that is the number that flatters the brand. The liner gets listed in small print or not at all.
It is also the only part held against skin for the whole session, in the warmest place on your body, under friction. A cotton outer with a polyester mesh liner is a polyester garment as far as your skin is concerned.
If a brand will not tell you what the liner is made of, that is the answer.
A garment is only as natural as the part of it touching your skin.
What goes into synthetic activewear
The catalyst used to polymerise PET, present in 80 to 85% of virgin polyester. It is in the fibre rather than on it, so it does not wash out. Lab testing found 125 to 470 µg/g in finished fabric, a fraction of which migrated into artificial sweat.
Polyester is chemically inert and will not hold colour without high heat, pressure and a stack of auxiliary chemicals. The colour range synthetics come in is a consequence of that chemistry.
Silver ion, antimicrobial, anti-stink, whatever the brand calls it. Added because the fibre smells, and washed out within a few cycles, which is why the smell comes back.
A single 6 kg wash of synthetic clothing releases more than 700,000 microfibres, and later work found synthetics shed during ordinary wear too. Natural fibres shed no plastic.
What merino does instead
It absorbs moisture into the core of the fibre and releases it to the air as vapour. Synthetics cannot absorb at all, which is why quick-drying means the sweat sits on your skin while the fabric dries around it.
Odour compounds stay bound inside the fibre rather than sitting on the surface where bacteria reach them. In controlled testing, a trained odour panel rated polyester significantly worse than natural fibre after identical exercise.
And it regulates temperature in both directions rather than holding heat in one, which matters most in the place a liner sits.
What to actually buy
Active Merino Liner Short
100% GOTS organic cotton shell, 100% merino liner at 17.5 micron, 100% cotton drawcord. No separate underwear needed. Two inseams, five sizes.
See it hereAll Natural Boxer
100% GOTS organic cotton and nothing else. No elastane holding it together. The layer worn longest and thought about least, and the cheapest place to start.
See it hereMerino Air T-Shirt
A 150gsm open knit of merino and Tencel that releases heat rather than holding it. The one for a hot gym, and the one worth packing.
See it hereRead the tag, not the campaign
Turn it inside out and find the composition label. Check the liner separately from the shell. If either lists polyester, polyamide, nylon or elastane in any