Synthetic Workout Clothes Smell Worse and Grow More Bacteria than Cotton, Says Study

New synthetic-cotton hybrid shirt could be the answer for better smelling gear

No, you’re not crazy—your synthetic clothes, the ones you bought for their supposed odor resistance, actually smell worse than your traditional cotton t-shirt after a workout, according to a recent study.

The research published in Applied and Environmental Microbiology tested 26 shirts (13 worn by men and 13 by women) after an hour-long spin workout and a subsequent 28-hour incubation period. After more than a day of storage in plastic bags, researchers studied the bacteria on the sweat-soaked shirts and “a trained odor panel” assessed the smell.

The odor panel concluded that the polyester shirts smelled worse than the cotton shirts and then the researchers took a look at the bacteria.

While new sweat has little odor, sweat that sits on clothes grows bacteria, which in turn causes odor. Researchers found an abundance of the bacteria micrococci on the polyester shirts. The micrococci was able to grow more easily on the synthetic material than the cotton. One of the researchers, Chris Callewaert, explained why the micrococci accounted for the bad smell.

They are known for their enzymatic potential to transform long-chain fatty acids, hormones, and amino acids into smaller—volatile—compounds, which have a typical malodor.

So how exactly are you supposed to keep the bacteria from forming on your clothes? First, be sure to remove your clothes from your dark, damp gym bag, then it would help to give your gear a quick rinse after the gym if you don’t plan on washing it right away.

Researchers also suggested fitness clothing companies could limit bacteria, and the stench it creates, by designing their synthetic shirts with cotton material in the armpit, where the most sweat forms. The mostly-synthetic shirt would keep an athlete cooler than cotton and enable better movement, while the cotton in key places would keep bacteria at a minimum. 

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