The gym shirt that makes you stinky

Determined five people working out on exercise bikes in a gym; Shutterstock ID 160505300; PO: today.com
Determined five people working out on exercise bikes in a gym; Shutterstock ID 160505300; PO: today.comShutterstock

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By Christa Sgobba

After a crushing workout, you don’t expect to smell as fresh as a bar of Irish Spring. But what clothes you wear during your session can actually up the odor ante from a mildly unpleasant whiff to a full-blown stench, research from Belgium found. 

Dude, that shirt reeks!Today

In the study, the researchers had cyclists wearing cotton, synthetic, and mixed-fiber T-shirts complete one hour of intensive biking. Afterwards, they sealed the sweaty shirts in a plastic bag for 28 hours. Then they performed a sniff test, and found that polyester tees smelled less pleasant and more intense, musty, sweaty, and sour than their cotton counterparts.

Polyester tees—and other synthetics—also showed high growth of a particularly smelly kind of bacteria called micrococci, which was practically absent in cotton samples.

“Micrococci transform the hormones and amino acids in the sweat into odorous compounds,” says study author Chris Callewaert, Ph.D. The kinds of bacteria that flourish in cotton don’t have that same stench-stimulating ability.

Even if you change into a new shirt after your workout, your gym shirt may still smell the next time you wear it. That’s because some odor compounds and bacteria likely remain after laundering, says Callewaert. He says future research still needs to be done to develop special antimicrobial agents that you add to detergent to wipe out the stinky kinds of bacteria. 

More from Men's Health: 

What you can learn from your sweat

How does sweat work? 

Practice proper sweatiquette

How to stay hydrated