No Sweat: The Truth About Performance Apparel

Performance-apparel companies have introduced garments that are made with cotton, synthetic and wool fabrics that they claim will improve your performance when you exercise. But no independent data back up these claims, and the results of our lab tests indicate that these shirts keep you about as cool as wearing no shirt at all.

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Ty Milford/Masterfile

If you have walked into a sporting-goods store in the past 3 years, you probably noticed that buying a shirt isn’t as simple as just picking up a cotton T-shirt in a color that you like.

These days, the shopping aisles are full of a variety of performance apparel—shirts, pants, jackets, socks and tights that are touted as being capable of  regulating your body temperature, keeping you comfortable and improving your physical performance.

Performance apparel rang up about $1.3 billion in sales in the United States last year. At least 60 companies now make these garments, which can cost roughly $10–$50 for a short-sleeve shirt and up to $300 for a pair of pants.

Performance-apparel commercials and print advertisements typically use college or professional athletes as endorsers. And the gear is marketed toward anyone who might work up a sweat—even toddlers.

“The lines between traditional ‘sports/performance apparel’ and normal everyday clothes are increasingly blurring,” says Janet Shim, who is a retail analyst for IbisWorld, which is a market-research group. “More consumers are wearing performance apparel to run errands and do everyday chores.”

If you’re wearing these clothes to run errands —or around the block—they aren’t improving your “performance.” We spoke with 14 exercise experts, physicians and scientists, and none of them nor the apparel-makers themselves knew of any independent, peer-reviewed evidence that performance apparel of any kind has any measurable influence on regulating temperature and improving performance. But all of our experts agreed that performance apparel will have no effect on regulating body temperature unless you’re pushing your body beyond its limitations.

“If you’re in an extreme environment, where you are challenging yourself beyond your physiological capability, then maybe one of these things can make a difference,” says Delia Roberts, who is a fellow at American College of Sports Medicine.

“But for a recreational runner, I don’t think it makes a difference.”

Through the Paces: Testing Three Fabrics

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We evaluated T-shirts that were made of three different performance fabrics that promised to wick  away moisture from the skin and keep exercisers cool and comfortable. Our results suggest that the fabrics might indeed keep sweat from accumulating on the skin, but this didn’t keep runners cooler or more comfortable than when they wore no shirt at all. (See "Through the Paces: Testing Three Fabrics.")

“These fabrics are probably more of a fashion statement than something functional,” says William Sands, who is the former head of Sport Biomechanics and Engineering for the U.S. Olympic Committee. (Sands also is director of Monfort Family Human Performance Laboratory at Colorado Mesa University, which conducted our evaluation.)

In other words, these shirts might make you feel more comfortable and look trendier at the gym, but we remain unconvinced that they’ll help you to breathe more easily, run longer or lift more weight.

WICKING OR STICKING? Most performance apparel is designed to wick (or pull) away moisture from the skin and through the clothing surface, so the moisture evaporates to leave you dry while you exercise.

Moisture-wicking claims are legitimate and typically are achieved by using one of two methods, says George Havenith, who has studied these fabrics at Environmental Ergonomics Research Centre, which he directs at Loughborough University in England.

The first way to promote moisture wicking is to apply a hydrophilic surface treatment, such as silica, to a fabric. This treatment allows the fabric’s fibers to attract water and pull it into the fabric and away from the skin, Havenith says. The second way is to use a knit structure that involves two types of fibers. The fiber that touches the skin absorbs little moisture, but it wicks away the moisture to the fiber that’s on the outside of the fabric, which is more absorbent, Havenith says.

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