Kevin Plank, left, a former college football player, founded Under Armour, a line of moisture-wicking compression garments designed to wear under sports uniforms.

There are two kinds of people in the world: those who know what Under Armour is, and those who are just finding out.

John Mincarelli is one of the latter, having stumbled onto Under Armour last year in an upstate New York branch of Dick’s Sporting Goods.

Mincarelli, who teaches the dark art of fashion merchandising at the Fashion Institute of Technology, is a hard man to impress. And perusing the racks of Nike, Adidas and Columbia that day, looking for some new workout gear, nothing did.

But then a display leaped out at him like some kind of marketing rhinoceros, which, since it features a colossally muscular mannequin modeled from a pro football player’s actual body, is roughly what Under Armour is designed to do.

“It totally grabbed my attention — just the name alone,” he said. “I thought, ‘This is brilliant.’ It implies all this power and protection and strength right off the bat.”

As any teenage boy could have told him, Under Armour is not new; it was founded in Baltimore in 1996 by Kevin Plank, a former college football player. But the brand hid in plain sight, like a purloined varsity letter, on the playing fields of team sports and the cameras of ESPN, where its discreet X-like logo (actually a U crossed with an A) and cartoonishly macho imagery made it all but invisible to the cold eye of fashion.

But anyone interested in a success story should look more closely at how Plank, 35, turned a pretty simple opening kickoff — a line of moisture-wicking compression garments designed to wear under sports uniforms, similar to those long worn by skiers and bicyclists — into one of the shrewdest plays in fashion history, not to mention one of the most provocative depictions of masculinity to emerge in the last decade.

“This is more about marketing than anything else,” said Marshal Cohen, the chief analyst for the NPD Group, which follows the apparel market. “It’s not a new product, it’s not new technology. They turned what was a niche market — they took the undergarment, your under-sports apparel — into something you actually wanted to wear.”

The result, he said, is that “they connect better with the consumer than any brand we’ve seen in a decade.”

Plank insists over and over that the brand is based on performance, a sentiment echoed by its fans, but he conceded that the Under Armour marketing campaigns have had very little to do with moisture wicking.

“Brands are effectively stories,” he said. “Our job is managing that.”

Now, one might think it reasonable that, with Batman breaking box-office records as if they were skyscraper windows, apparel made of superhero Lycra (actually, it’s a women’s lingerie material) should have struck a nerve. But Under Armour is made for (or at least marketed to) iron-man athletes, not the fantasy Iron Man of the movies. The company’s success — $314 million in sales for the first half of 2008, a jump of nearly $70 million over the first half of 2007, when the company went public — would be remarkable even if the economy were not pancake-flat.

And while the Under Armour marketing machine likes to evoke Plank’s rough and tumble football background, the company has been as cunning as a chess pro in cultivating its image and fan base. This is apparent in its testosterone-juiced “Protect This House” television ads featuring hugely built football players (like the fearsome-looking NFL veterans Eric Ogbogu or Ray Lewis) sweating, shouting and working up as if for battle.

Extreme as they are, they send a message of authenticity (one of Plank’s favorite words) and aggression to a select audience, unlike ads from sporting goods giants like Nike and Reebok aimed at more general audiences.

The worked-out fantasy has also endeared it to a fan base most likely to carry it into the future as a major lifestyle brand: teenage boys.

“This is the brand for them,” Beth Boyle, the senior public relations manager for NPD, said of her two sons, ages 13 and 15. “Even if I say to them, ‘If we get the cheaper brand, you can have two,’ they say, ‘No, I’d rather have just one.’ ”

Only time will tell whether the Under Armour formula can propel it to the size of Nike. Mincarelli, the Fashion Institute of Technology professor, is not sure. While he likes to wear Under Armour at the gym, he doesn’t feel the urge to wear it anywhere else.

“I’d love to see the brand images of Under Armour go head to head with Abercrombie,” he said, chuckling. “I think Under Armour would crush them. But you know, I’d rather own the shirt from Abercrombie.”Reaching out to women

Teenage boys and their heroes may have made the brand what it is, but Under Armour is now thinking outside the gridiron. Women’s wear was introduced in 2005, and the company has sponsored women athletes and teams.

Founder Kevin Plank said he hopes the sector will be bigger than menswear, though it has yet to inspire the kind of loyalty that the menswear has.

The company’s first mainstream athletic shoe, a cross-trainer, was introduced early this summer (after being previewed in the company’s first Super Bowl ad) and has done well, according to Omar Saad, a retail analyst at Credit Suisse. And this year the company opened its first two stores, in malls in Annapolis, Md., and Aurora, Ill., a suburb of Chicago; and a third one opened in August, in Natick, Mass., a suburb of Boston.

Suzanne Karkus, a veteran of Calvin Klein and Izod, was recently brought in to oversee apparel, much of which is either very tight or very baggy, and appeals to men who answer those descriptions as well. (A new intermediate “fitted” style is coming in spring 2009, she said, as are more up-to-date color selections.)