You probably do not often hear someone talk about their favorite Sports Bra but I'm a fitness editor, and that's why it's part of the job description to look for performance fabrics. And the truth is that what your Activewear consists of is one of the most important factors in determining whether or not you feel comfortable exercising. The fabric affects the fit, feel and appearance of a garment. These are all things that you are probably interested in, at least to some extent. And there's one thing I've been obsessed with recently: merino wool.
I discovered the true beauty of merino wool several years ago when I tested a Smartwool sports bra for SELF's Annual Fitness Awards . , This simple, unpadded, stretchy bra with thin crossed straps became my best companion when hiking. Since then we are strong. The fabric nestles softly against my skin, never digs into me uncomfortably and minimizes sweat. I carry it while hiking and when I go camping, I usually wear it only in bed – it stays on almost three days. Which, yes, that sounds disgusting. But I swear, it's not nearly as bad as it seems. Let me explain.
What is merino wool?
Merino wool is wool that comes from Merino sheep. This type of wool is most commonly used for clothing because it is soft and extremely fine – about three times finer than a human hair, according to a representative of The Woolmark Company, a nonprofit organization representing the Australian wool industry. You may know thick, chunky, itchy wool sweaters that are not made of merino wool. In the past, coarser wool was more common in clothing because it was cheaper than merino wool. Over the years, however, new textile industry innovations have helped lower the price of more luxurious merino wool, according to The Woolmark Company. Now, most of the wool you find in clothing is merino wool. (The thick, itchy stuff is usually reserved for items such as sofa cushions and carpets.)
Merino has traditionally been used in winter sports such as downhill skiing. Smartwool, an American company that sells merino wool blends, initially made 100 percent merino wool socks to keep feet warm on the slopes, says Molly Cuffe, head of global communications at Smartwool, to SELF. Merino appeared to be the perfect fabric because it is softer than traditional wool but still offers the benefits of natural fiber, says Cuffe Administration. "Generally, wool helps keep you cooler in summer and warmer in winter, as it works in a natural way with your body's heating and cooling systems," Cuffe explains.
The Woolmark Company explains that this is due to the ruffled structure of wool fibers that form small air bubbles that insulate but at the same time allow the escape of moisture.
You probably once heard the term "sweat-wicking" quickly evaporate. Wool does this in a natural way and many synthetic fabrics made for active wear are designed for this. Sweat-wicking is a good thing because it prevents sweat from soaking your clothes and sitting on your skin. (In cold weather this can be dangerous as the wet can catch cold and increase the risk of overcooling .)
Wool is also considered odor resistant. This, in turn, is due to its structure, which allows it to keep away dirt in principle. Since moisture quickly escapes from the fabric, it can be less wet (sorry) than other fabrics. Of course, a wool T-shirt will not improve your actual BO. But the garment itself will probably smell less rancid after an intense workout than a cotton or spandex shirt.
The Woolmark Company people also say that you do not have to wash your merino wool clothes after each time you wear them because it will take longer for them to stink. Just hang it up to release air – which will probably extend the life of the garment.
In my experience, every merino wool garment I wore has withstood the hype. When I go camping and walking, I wear the same things again, and yes, after a few erosions it starts to stink, but never after the first time. When I wear only a merino wool T-shirt for work or training, sweat dries noticeably faster than some shirts that seem to stay soaked for a day or two after exercise.
Where to Find Merino Wool  Merino wool can be a perfect garment on its own, but is often blended with fabrics like nylon and spandex in sportswear for the right amount of stretch and durability. Cuffe explains that garments are made from 100 percent wool and become somewhat baggy in the wet, "so you lose some performance factors." This is an important reason why brands choose to mix wool with other fabrics. "For example, it does not make much sense to make 100% woolen running shorts, so ours have a very light, soft synthetic exterior, but the inside is lined with merino wool, which promotes breathability," says Cuffe. (Also, 100 percent merino wool can be quite expensive.)
Below are some great merino wool products that are worth trying on if you want to give the fabric a chance. Editors or sources. If you buy something through our retail links, we may earn a partner commission.