This Is Why Your Gym Clothes Smell Terrible—Even After You Wash Them

While traditional laundry detergent removes odors and stains from cotton, that same soap won’t de-stink athleisure

Here are four tricks to washing the sweat from your high-tech workout clothes. Unsplash/Kristopher Roller

You may have a cleaner mind after yoga class, but your workout clothes are a playground for dirty, dirty microbes that defy traditional detergents.

Blame the odor on gas-producing bacteria, says Lee Silverman, managing director of WIN laundry detergent. Silverman explains the basic science behind smelly Lululemons: oil and water don’t mix. Cotton T-shirt fibers are rope-like, with lots of nooks and crannies—perfect for absorbing H2O and deflecting body oil. High-tech performance gear, on the other hand, is made of smooth synthetic tubes, similar to fishing line, that deflect water and allow sweat to evaporate off the skin. Chemicals in this fabric make clothing “hydrophobic,” fearful of water and perspiration. This “wicking” translates into a cooler workout with less friction on the skin. But it also means fabric absorbs body oils, the first event in a foul-smelling melodrama.  

Over time, your favorite workout clothes can become the perfect setting for “Germs Gone Wild,” especially if garments live in dark, warm places like gym bags and lockers. Laundry detergents like Tide, which effectively pull stains and odors out of cotton, really don’t work on sports clothes that require simple, alternative treatments to remove sweat.

“Fifteen years ago, a person might have had one or two pieces of performance wear,” Silverman says. “Today active people have as many as 15 pieces of athleisure, which means a lot of laundry.”

Here are four tricks to washing the sweat from your high-tech workout clothes, for a less smelly summer:

  1. Rinse athleisure pieces immediately after use. No one preaches this louder than Anina Young, owner of Brazen Lingerie in New York City, who feels personally insulted when clients don’t respect their sports bras. “Take care of your girls and they’ll take care of you,” she often tells customers. After soaking workout clothes in plain water, Young recommends pressing the items between two hands to remove excess moisture. Do not twist or wring your workout clothes, which can damage the material and make it less supportive.
  2. Do laundry once a week. Just like you separate whites from colors, you need to treat workout clothes as its own animal with its own time in the washer. While traditional laundry detergent removes odors and grass stains from cotton, that same soap won’t de-stink synthetic gym clothes. Silverman suggests sport-specific products like WIN instead of Tide to remove sweat and body oils. Young likes Soak, a laundry detergent that doesn’t require rinsing. For delicate items like bathing suits and sports bras, the soap is ideal for hand-washing intimates in the sink. Homemade once-a-week remedies include putting all workout clothes into a tub of water with one cup of white vinegar, two teaspoons hydrogen peroxide and two teaspoons baking soda. Let the brew soak for an hour before dumping all gym gear into the washing machine with one cup of white vinegar and two tablespoons of baking soda. 
  3. Whatever you do, think dry. Odor-causing bacteria thrive in the damp, so don’t let your sweaty clothes ferment in the hamper. At the very least, hang your shorts up after a run. When you have time to machine wash your workout clothes, tumble dry them on low, says Silverman. Do not use dryer sheets, which can destroy wicking properties. Cotton gym clothes should be dried on high. For delicates, air dry by hanging garments on a regular hanger on the shower curtain road. If ventilation is poor, put the hanger on the knob of an open kitchen drawer and catch the drips with a towel on the floor.
  4. Alternate your gym clothes. Instead of wearing the same sweaty shirt every day, extend the life of your garments by buying several. Buy two of the same sports bra and rotate them, Young says, adding that fuller-breasted women may benefit from three bras for reasons beyond smell. Supportive fabric gets stretched during intense exercise. As a result, the fibers need time to recover between workouts. The morale of this bosomy tale is that three bras are better than one when it comes to performance and stench. The same holds true of other malodorous clothing like bike shorts and jock straps.

Ann Votaw is a freelance writer in New York who has a M.A. in Health Education. She teaches yoga and physical fitness to adults 60 and better.