Woman after workout with towel around neck

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All-Cotton T-Shirts

Let's disregard the fashion statement you're making by wearing an old, stretched-out shirt. The most important reason to leave this beloved tee at home is that cotton absorbs sweat and doesn't quickly release it through evaporation. Wearing heavy, wet cotton against your skin can give you the chills and cause irritation. Opt for technologically advanced fabrics that hold moisture away from the body, like CoolMax, Capilene or Dri-FIT. If you aren't comfortable in the clingy fit of these stretchy fabrics, try a double-layer top that offers two shirts in one. One example: A supportive tank made of Play Dry wicking fabric is covered by a looser cotton tee with flattering ruching on the sleeves.
Scantilly clad woman stretching her leg on steps

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Untested Tanks

Your tank top may look modest when you're standing up, but it becomes X-rated as soon as you bend over to do push-ups. To avoid flashing everyone at the gym, check your top view from a variety of different angles before leaving home. Bend forward, reach and lean sideways and do jumping jacks to assess the bounce factor. Even non-impact activities require support, says Taj Harris, a certified personal trainer and group fitness instructor at Crunch gyms in New York City. "I had a woman in one of my spin classes who was rather busty," she says. "Her sports bra didn't fit, and riding the bike was causing her breasts to spill out all over the place. It was very distracting to everyone in the class—including me!" Cleavage-proof tanks have a higher neckline that stylishly limits indecent exposure. For those who require extra support, Bounce offers an option for DDD athletes.
Silver thread, spool and needle

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Silver Threads

Nanosilver is said to fight bacteria, molds and fungi, so a few years ago, companies began incorporating nanosilver particles into fitness apparel. It seemed like a flashy way to keep sweaty gym clothes from smelling stale. But the antimicrobial benefits may not last long. Researchers at Arizona State University found that after about four or five washings, nanosilver-treated fabric lost about half its particles, which then washed out into the water. Although the long-term effects of these ingestible particles on wildlife is still unknown, environmental groups have started sounding the alarm on nanosilver's ability to neutralize positive bacteria in some ecosystems. Until conclusive studies are released, save the money you would have spent on anti-odor clothing and put it toward laundry detergent instead.
Woman in baggy purple pants wearing headphones

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Baggy Sweatpants

Long, baggy pants can catch on exercise machines like stationary bikes, where the hem can get stuck on the pedals or the water bottle holder. Harris has had to help untangle pants from bikes in some of her spin classes at Crunch. Long pants are also out of place in another class Harris teaches: pole dancing...and not for the reason you're thinking. Harris says that pants-clad legs slide right off the pole because they don't provide the same kind of grip that bare flesh does. Your best options for most classes are capris, slim-fitting long pants or shorts.
Women doing aerobics

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Thong Underwear

It's true that inconspicuous underwear looks better under slim-fitting shorts or pants. But thongs are not the best solution. When you sweat and move around during exercise, rectal bacteria can travel along the thong to the vagina, which can lead to infections both in the vagina and the urinary tract. This type of underwear can also exacerbate an existing irritation. Instead, pull on seamless, nearly invisible underwear bottoms in sweat-wicking material.
Woman walking with weights and shirt tied around waist

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A Long-Sleeve T-Shirt Tied Around Your Waist

We're forever indebted to the first woman who thought of this, as it's not only a convenient place to put T-shirts when we aren't wearing them, but it also makes for a kicky little skirt. The problem is that, at the gym, this style adds unnecessary bulk that can get in your way. And as Harris says, "You think you're being sly in covering up, but everyone's eyes are automatically drawn to what you're covering up." If you can't part with that extra layer, consider this ingenious T-shirt-wrap, or suit up in a running skirt or skort. They're more streamlined and offer built-in pockets.
shoes with toes

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Shoes with Digits

These next-to-naked shoes have gained an enthusiastic following of runners and others who swear the unique footwear relieves knee, joint, foot and back pain. To some gym owners, however, the shoes can be a liability. Many gyms have a policy against bare feet in the free-weights area, and some worry that these foot coverings don't offer enough protection from falling dumbbells. If you won't pump iron in anything else, check with management to make sure they're allowed in that part of the gym.
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