If the sour stench of long since-dried sweat seems to pervade all your workout clothes, you're not alone (actually, there are quite a few embarrassing problems fit guys have); but you are in luck. Brand new research published in the Journal of Chromatography A reveals where the odor's coming from and how to eliminate it.
Why You Smell
First, you need to know the problem is only partially your fault. Your sweat is odorless until it mingles with bacteria—namely Corynebacterium and some Staphylococcus species—on your skin. When this happens, really nasty-smelling volatile organic compounds (VOCs) are created and nestle into the fibers of your clothes the researchers explain in a press release.
What's more, in light of protecting the environment, conserving resources, and reducing skin irritation, many people have turned to using fragrance-free detergents and keeping the water temperature during washing machine cycles cool. But this eco-friendly 68˚F cycle doesn't always do the trick.
In order to find the best way to keep clothes smelling fresh—while still protecting the planet—researchers from Northumbria University first had to identify what volatile organic compounds are causing the offensive odor before washing, after washing while still wet, and after drying; if these compounds are eradicated during the washing process; and how best to destroy them at different wash temperatures (which will be explored in a follow-up study).
In the study, researchers gave 6 men and 2 women a new pair of socks. Participants were asked to wash their feet with water and dry them before wearing the socks for at least 10 hours in shoes. After, the men and women put each sock into a separate sample bag and stored them in the dark overnight. In the second phase of the study, 9 men were each given a t-shirt to wear for two to three hours while they played in a five-per-team soccer tournament. After, the t-shirts were bagged separately and refrigerated. Participants were prohibited from applying deodorant or moisturizer.
The (unlucky) researchers then sniffed each sock and t-shirt, and graded each on a scale of 0 (no bad odor) to 10 (extremely bad odor). They also took samples from the toe, ball, and heel of the socks as well as the armpit of the t-shirts to analyze the VOCs causing the smells.
Next, the researchers washed the t-shirts and socks in a Tergotometer, a laboratory-scale washing machine that simulates the action of many mini domestic washing machines at 68˚F, using non-perfumed detergent for one hour; after, they tested the samples again for VOCs both when they were still wet and after air-drying indoors overnight.
The team identified six main VOCs:
1. Butyric acid (strong, rancid butter-like odor) *
2. Dimethyl disulfide (unpleasant, onion-like odor) *
3. Dimethyl trisulfide (powerful odor) *
4. 2-heptanone (banana-like fruity odor)
5. 2-nonanone (fruity, floral, fatty, herbaceous odor)
6. 2-octanone (apple-like odor)
*Highest overall concentrations in socks and shirts
In the sock portion of the study, the economy setting wash cycle considerably reduced the concentration of VOCs from the pre-wash to post-wash anywhere from 32–79 percent for the "onion-like odor," 74–93 percent for the "powerful odor," and 58–93 percent for the "rancid butter-like odor."
In the t-shirt portion of the study, there was also a significant reduction in odor, reducing VOCs from pre-wash to post-wash anywhere from 25 to 98 percent. Now, researchers need to figure out the optimal temperature
In the washing process you've got three steps: the pre-wash (adding dirty clothes to the washing machine), the washing process itself (adding powder or liquid detergent), and the post-wash (the damp state your clothes sit in until you remove them to dry.
Pre-Wash Tips: To ensure you're not creating a breeding ground for bacteria, don't store your sweaty gym clothes in an air-tight plastic bag; you might think it's keeping the odor's locked in, but it's also sealing in heat and moisture, which promote the growth of odor-causing bacteria. You also want to wash your clothes as quickly as possible so they don't fester together in your dark, damp laundry bin. Try to separate them from your other clothes, too.
Washing Process Tips: You can enhance detergents with products like Febreze In-Wash Odor Eliminator or even 1 cup of white vinegar, which naturally eats up odors and serves as an antibacterial agent to kill bacteria, mold, and germs. And while the researchers haven't found the optimal temperature to eliminate foul odors, hotter water temps (about 104°F) will do a better job of burning off bacteria. Do a small load and use hot water on your super-smelly duds (if you use the tip above and separate your gym clothes from the rest), and keep the temperature low on all your other loads.
Post-Wash Tips: The researchers believe the VOCs were washed mostly by the detergent and water and destroyed even more by evaporation during the drying process. And while they air-dried clothes in the study to conserve energy, you can toss your clothes in the dryer with a dryer sheet if they're not getting as fresh-smelling as you want. But if you want to be environmentally savvy, just make sure you're drying off the inside of your washing machine. Biofilms can build up inside the drum—especially the drum gap/rubber door seal. Use a towel to wipe down any excess moisture and keep the washer door propped open to fully dry.