Why workout clothes smell even after washing

Lisa Ryan, 26, New York City marketing manager and workout enthusiast, is frustrated: "I exercise every day, and no matter how frequently I wash my gym clothes, they never seem to be fully clean."

Ryan isn't alone. Almost everyone's gym clothes stink, even after washing.

To understand why, we must first understand what causes odors in textiles, says Mary Johnson, a principal scientist for Procter & Gamble. Seventy percent of laundry dirt is caused by body soils that are invisible to the eye - sweat, skin cells, salt and a waxy fat called sebum. If they aren't removed with an effective detergent, these soils accumulate and settle in the fibers. The most difficult to remove is sebum because "it is very sticky and as it sets in the fibers it ends up attracting other odor-causing soils that then adhere to the fabrics."

Washing clothes in hot water melts the sebum, but most of us are not working out in clothes made from natural fibers such as cotton that can withstand hot temperatures. Instead, we are wearing clothing made from synthetic fibers that require cold water washing, so the sebum is literally sticking around.

"This problem is exacerbated in performance clothes that contain channels or grooves that enhance wicking," Johnson says. "Body soils can become trapped in these grooves, making them even more difficult to remove. That is why odors are a common problem with performance fabrics." Johnson and her co-workers call such fabrics "dirt and odor magnets."

Johnson stresses the importance of using the right detergent to eliminate odor-causing soils. "Some laundry detergents do not perform any better than water alone in removing body soils that cause odors." Heavy perfumes in these detergents mask the odors out of the wash, but as the perfumes fade, the odors become noticeable again. "If your clothes look clean but smell bad, they're not clean."

Drew Westervelt, founder and chief operating officer of HEX Performance, which makes a new-generation detergent specifically formulated to target odors in synthetic fibers, says the fabrics we use have changed but our detergents have not. "More than 60 percent of today's laundry is synthetic or blended fabrics, but traditional detergent was never designed to clean those fabrics - they were always focused on stain removal. But odors from bacteria, mold and mildew are now the real problem and they can't be dealt with by simply covering them up with added fragrances."

HEX detergent has no discernible fragrance and is a clear liquid (it's closer to the consistency of water than traditional liquid detergents). Westervelt says HEX targets bacterial stink with its proprietary science but also removes visible stains. And although it was created to clean synthetics, he says, it works just as well on natural fibers. HEX is eco-friendly, biodegradable, nonallergenic and has another benefit: It adds an odor-fighting shield to fabric fibers so that, as the item dries, odors are actively prevented from developing again. HEX also makes an anti-stink spray you can use on shoes, sports equipment or gear that can't go in the washing machine - just spray and let dry.

Combating smelly synthetics is a growing market, and other brands are cropping up as well. Canadian company Sport Suds makes a non-residue, non-fragranced powder effective in both hot and cold water. Paul Yung, president and founder of the company, says Sport Suds detergent loosens debris and contaminants from fabrics and then rinses them away, making sure nothing is left in or on the fabric after the wash. "Conventional detergents do the opposite," he says. "They leave behind things like fragrance, softeners, anti-stain agents and other items."

Tide has also come out with its own products to deal with the stink. Tide Plus Febreze Sport Odor Defense liquid detergent and Tide Pods Plus Febreze 4-in-1 Sport Odor Defense remove odor-causing soils even in lower temperatures, plus they have added enzymes to break down stains. They also have anti-redeposition polymers that make sure soils in the wash water don't re-attach to your clothes. Johnson says this is especially important in high efficiency washers that use very little water for very large loads, thus leading to very soiled wash water.

Whatever detergent brand you end up using, it's important to use the correct dose when washing your athletic gear. "Dose based on the size of your load and how soiled it is," says Johnson. "Using too little detergent not only means that your stains won't be removed, but it also allows body soils to build up on your fabrics, resulting in odors, dinginess, and dullness."

And don't leave athletic gear or towels in unlit areas or your gym bag while they are damp. Johnson says mold and mildew can grow within six to 12 hours. Always allow your clothes or towels to air dry before placing them in a hamper or another enclosed space. And since odors transfer between clothes, Johnson recommends having a separate laundry basket for workout gear to keep it away from your work and everyday clothes.

Lululemon, a leader in athleisure wear, recommends the following care instructions to prolong the life of your high-performance gear:

• Read first: Always check the care and content label for information on how to care for your clothing.

• Cold wash, air dry: Machine wash items in cold water and lay them flat to dry. This helps protect the life of Lycra and other synthetics and maintain the shape of your clothes.

• Brights stay with brights: Wash bright colors alone before you wear them. Continue to wash brigh-colored gear with similar colors. When wet, keep bright colored items away from other fabrics.

• Turn items inside out: Turning your clothing inside out before washing will protect your clothing's outer surfaces and allow detergent to tackle soils head on.

• Wash like items together: Wash synthetic fabrics together and avoid washing them with anything abrasive, such as denim or garments with Velcro or zippers.

• Avoid Mixing luon with cotton: Wash luon separately from other materials, specifically cotton (especially towels) - the cotton fluff will stick to the luon.

• Do not use fabric softener: Avoid using fabric softener because it coats technical fabrics and inhibits their wicking capabilities.

Mayhew, a "Today" show style expert and former magazine editor, is the author of "Flip! for Decorating."

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