There's no better testament to athletic effort than a sweat-soaked T-shirt. When a jock perspires, he's struggling and striving his way to glory. The guy who doesn't break a sweat? He's a bench-warmer, a goldbricker, a lazy bum.
At least that's how it used to be. Companies like Under Armour, which announced a few weeks ago that it's going public, now make a fortune by demonizing perspiration. Sweat-fighting athletic gear, known in the sportswear industry as "performance apparel," is now a multibillion-dollar business. The craze has even spread beyond sports: Haberdashers are now making perspiration-abating business suits.
Sweat cools your body when it evaporates from the surface of your skin. But sometimes the volume of sweat you produce is too great for it all to disperse. Instead, the watery excretion gets soaked up by your cotton T-shirt, which gets damp and gross as it slurps up the excess moisture. Performance apparel solves that problem by "wicking" sweat away from your body, just like the wick of a candle absorbs liquid and draws it upward. The sweat-removing shirts, with their polyester-blended fabrics and chemical treatments, pull perspiration away from the skin and push it through the clothing's surface, where it evaporates. The result: a comfortable, dry athlete.
Since I'm the sweatiest guy I know, I took some wicking gear for a test schvitz. In my unscientific opinion, the stuff works. Under Armour's Heat Gear Full T-Shirt (you can find one for about $25) stayed light and dry as sweat cascaded down my face during an hour-long run. The shirts I tried with "Dri-release microblend performance fabric"—a technology developed by former DuPont scientists and licensed to apparel producers—were even wickier. I wore an Anvil Dri-release short-sleeve T-shirt (about $10) while jogging in the August heat and an Anvil Dri-release sleeveless teeafter getting out of the ocean without toweling off. Both shirts got bone dry in a frighteningly short period of time. Finally, I put on Brooks Sports' Pulse T (about $44), which comes with "moisture transfer polyester" and heat-release panels in the armpits and chest. The special panels "worked" a bit too well for my taste: Throughout my run I felt a cold tingling sensation in my chest and pits. Maybe a higher-performing athlete would enjoy the sensation. It just freaked me out.
My experience with the Pulse T made me wonder whether there was a darker side to this stuff. Is it possible that these shirts do their job too well? A small company called TR Gear thinks so. "Our extensive research shows that the high wicking fabrics currently used in the industry can actually increase the risk of injury, fatigue, overheating, and dehydration by not allowing sweat to affectively cool the body through evaporation against the skin," reads the company's Web site.
Mike Smoltz, the founder of TR Gear and the brother of Braves pitcher John Smoltz, told me that newfangled wicking shirts counteract the body's natural thermal regulation mechanism. By drawing sweat away from your skin as soon as it rises to the surface, he says, your body won't cool properly. That will make you sweat even more, which will lead in turn to dehydration and compromised muscle performance.
TR Gear claims that its proprietaryfabric, called TR37, is superior to cotton and wicking shirts because it allows sweat to evaporate on your body without getting soaked itself. They insist that TR37 thus does a better job of regulating your core temperature and ensuring that you stay hydrated. Earlier this year, the technology was named "one of the top five innovative products" at a major industry trade show.
I tested TR Gear's form-fitting workout shorts, the same ones John Smoltz has worn under his uniform for the last four years. While they felt pleasant enough, it was impossible for me to tell what they were doing to my core temperature. For what it's worth, they were more comfortable than the form-fitting biking shorts I've worn. The shorts did get a little damp for my taste, though, far more damp than the better wicking shirts I tested. Mike Smoltz told me my thigh muscles might feel cool after my long run, but when I touched them they seemed as warm as the rest of my body.
The company says it has done "extensive research" on its products, but Mike Smoltz told me that no independent studies have been done on TR37. There has been at least one study on the effects of workout gear on core body temperature. East Carolina University's Dr. Tim Gavin evaluated the effects of working out in hot weather while wearing a Speedo (i.e., without clothes), cotton fabric, and wicking gear. Gavin's conclusion: Both performance apparel and cotton have little effect on core body temperature. Gavin told me it is theoretically possible that the Smoltzes are onto something. But in order to know for sure whether some clothes wick sweat too quickly, he'll have to expand his original experiment to include extreme weather conditions, such as when it's really humid and more difficult for the body to cool down.
Dr. David Pascoe, who tests workout gear for Auburn University's sports teams in his Thermal Lab, told me there's only so much influence a garment can have on an athlete's body temperature. He's also quick to say that boring old cotton is still a very good fabric for sportswear: It's lightweight, doesn't irritate the skin, breathes well, can take repeated washings without deteriorating, and is extremely cheap, especially compared to pricey performance apparel.
Cotton might not be the demon fabric that performance apparel manufacturers say it is, but I'm going to keep my Under Armour shirt. The wicking thing was nice, but more important, it held my excess midsection pounds in place like a shiny sports girdle. Who could go back to cotton after that?