Here is why some clothes are smellier than others after a workout — and what you can do about it

Ever wondered why your polyester workout gear smells like it’s gone ten rounds in the ring with a skunk, while your cotton tee just has a mild funk? Researchers have cracked the case, and their findings are as enlightening as they are stinky.

Smelling out the situation

To get to the bottom of this smelly situation, researchers soaked different fibres in a simulated sweat solution, and then measured the release of various odour-causing compounds. This method provided a more realistic way to understand how our clothes get stinky, as traditional methods often overlook that body odours transfer to fabrics primarily through liquid sweat, not just airborne sweat vapours.

The study found that polyester is an odour hoarder. Unlike cotton and viscose, which are plant-derived (cellulosic) fibres and tend to release less of the odour-causing compounds, polyester, nylon, and wool hold onto these compounds.
“Polyester is notoriously smellier after a workout,” explained Rachel McQueen, a clothing and textiles scientist. “But now we know why. It’s all about how these fibres interact with the sweat and odorants.”

What makes sweat stinky?

Sweat is mostly water but also contains oily compounds that bacteria love to munch on, creating those familiar gym-bag odours. Cellulosic fibres like cotton and viscose absorb more water and less of the stinky, oily stuff. Polyester, on the other hand, repels water but greedily soaks up those oily compounds and odorants.

This means that while your cotton shirt might get damp, it’s less likely to become a walking odour bomb compared to your polyester gear.

Beating the stank

The study also found that nylon and wool initially absorb a lot of odorants but also make the stink disappear faster than polyester. After 24 hours, the smell in nylon and wool was almost as faint as in cotton and viscose. So, if you’ve got nylon or wool workout clothes, you might be able to skip a wash now and then — just hang them out to air and let nature do its thing.
"Basically, if you're concerned about smelly clothes, then keep away from polyester. Even with some of the anti-odor claims on some clothing labels, you might want to be cautious,” McQueen explained. “If the anti-odor property is due to an antimicrobial, it may not be as effective as you think, because there's another mechanism in play, which is all about the fibre chemistry and the interaction with odorants."

The findings of this research have been published in Textile Research Journal and can be accessed here.