Fashion: Sneakers? Not.

The Japanese designer Yohji Yamamoto creates the sort of high-art apparel often referred to as innovative, cerebral and, on occasion, unwearable. Only the particularly adventurous–and wealthy–are likely to don his elaborately constructed designs, with their asymmetric hemlines and exaggeratedly large collars. But some of his most coveted offerings of late are supremely practical. Last year Yamamoto teamed up with Adidas to design a line of sneakers, and the results–slip-ons in floral patterns or brocades, for example–are comfortable and versatile enough to wear with his own collections or even jeans from the Gap. Of course, at $240 to $590 a pair, they aren’t targeted at the customary Gap shopper. But that’s not the point, really. For these Adidases represent the high end of the hot new market that is women’s sneakers; women now spend nearly $4.5 billion a year on athletic shoes, and the figure is growing fast.

Until a few years ago, athletic-shoe companies designed their women’s lines to mimic their men’s lines, only in smaller sizes and pastel colors. Today virtually every athletic-footwear company, from Nike to Reebok to New Balance, is competing to offer women shoes designed expressly for them. Not only are the heels tailored for the narrower female foot, but the shoes may come backless or toeless; they may be styled to resemble Mary Janes or bowling shoes; they may be made of woven or mesh fabrics; and they come in a panoply of colors. They are sturdy enough to wear while smacking a tennis ball and chic enough for post-doubles cocktails. The majority of the shoes sell for $70 to $120. The marketing niche even has a name: athleisure.

The athletic-footwear manufacturers started experimenting with sneaker design more than a decade ago, but initially for the men’s market and then primarily with gadgetry purported to offer technological advantages on the court or field. (Remember the Reebok air pumps?) Despite such marketing, surveys showed that in almost 75% of sneaker purchases the decision to buy was based on how the shoes looked or who endorsed them rather than on their intended purpose.

Fashionization of women’s shoes started to take off in 1997, when, in an attempt to ignite its lackluster image and sales, Puma enlisted revered designer Jil Sander to create a limited-edition women’s running shoe. It was basically a standard-issue Puma, with a gold Jil Sander logo. But the fashion cognoscenti loved it, and suddenly the Puma name was chic.

At about the same time, Skechers, a Southern California-based footwear company that launched in 1992, started making great strides with teen and female consumers by keying in on trends and marketing itself as a “lifestyle” company. The flat, well-cushioned Skechers boasted comfort and the latest sneaker technology, but the company’s advertising emphasized the shoes’ stylish look.

Now the golden rule is that for men and women, fashion is as important as technology. With that in mind, the women’s market offers unlimited possibilities. Women account for only one-third of the $14 billion in annual athletic-footwear sales, but evidence suggests they would be willing to spend more. “Women tend not to be price sensitive. They will pay full price,” says Carol Murray, senior analyst for apparel and footwear at Salomon Smith Barney. “And it’s clear that color and fashion are as important to women as performance.”

So when Adidas teams up with Yohji Yamamoto to produce sneakers that cost a paycheck, think of them as a lure, or what Adidas America marketing director John Kawaja calls an “image ploy.” Says he: “We’re never going to build a business out of Yamamoto products, but we’re seeding the market and trying some different things we may be able to commercialize down the road.”

This is the same strategy long employed by the most venerable fashion houses, which stage elaborate haute-couture shows featuring creations that few can afford but everyone lusts after. The resulting publicity draws throngs of customers into retail outlets to browse. The real money is then made through sales of items like perfume and scarves, or in this case, $100 sneakers.

Or in the case of Adidas, the line of $100 ClimaCool shoes, due out this month. Sure, the technology purports to control the temperature inside the sneakers, but their greatest appeal may lie in their variety of colors and sports-category options. The company also has a new collection of sneakers that resemble bowling shoes, available in light coral and lemon yellow.

The challenge in the women’s market concerns image. For men, Nike can snag Michael Jordan, tack his name onto a shoe and watch as pair after pair fly out of Athlete’s Foot stores everywhere. For women, designers have to find another way to generate sales. Thus Martin Lotti, Nike’s global creative director of women’s footwear, travels the world seeking visual inspiration that he can combine with the company’s technology. As he puts it, “If you have an ugly shoe, no one is going to buy it.”

On a trip to Bilbao, Spain, two years ago, Lotti was struck by the wildly spiraling metallic towers of the Guggenheim Museum. “It looked so different from everything around it,” he recalls. “I wanted to do the same thing with a shoe.” Eighteen months later, Nike unveiled the Air Max Specter, a slip-on sneaker with an upper sole of grooved, sinuous curves, available in the same titanium gray as the museum’s exterior. The shoe became the season’s No. 1 seller.

It should be no surprise that the sportswear powerhouse has thrown its weight behind the women’s market. (For one thing, there are millions to be saved in endorsements.) When Nike started its women’s division in 2000, women generated about $1.5 billion in annual global sales, or 20% of the company’s total. The goal is to boost that to one-third, via products such as the Visi Havoc, a $70 sling-back, and the Air Rift, a split-toe design that has been spotted on actresses Sarah Jessica Parker and Gwyneth Paltrow.

The company has launched a Nike Goddess website (motto: Look Good. Kick Ass) and will open its second Goddess store in Los Angeles in mid-March. Still, for all of Nike’s technological and marketing prowess, the Portland, Ore., company may have picked a fight in the wrong ring. “When you open the door to the fashion sector, there are so many more players,” says Michael Atmore, editor in chief of Footwear News. “Skechers has done an incredible job. Puma is very hot, and Adidas and Reebok are making every effort to fight for their share.”

It’s not about just sneakers anymore; it’s about style, which is why the glossy fashion magazine W featured Christian Dior clothes with Vans sneakers in its February issue. It’s also why high-end labels such as Gucci and DKNY intend to win over fans by peddling shoes that look perfect for the amateur athlete and are priced for the full-time debutante. Prada, for example, has a line of sneakers, made of canvas with tread soles and laces, that still sport the Prada logo. So who cares if they offer little boost on the basketball court?

This spring Nike will roll out Visi Mazy, a sling-back in woven fabric, available in “lime chill” and “midnight navy.” It will compete against a line that Skechers is developing in denim and a sneaker from Puma created by the Japanese designer Yasuhiro Mihara. As Tony Bartone, Puma’s director of brand management, promises, “These will not be found at Athlete’s Foot.” Which is exactly why the women’s market could prove to be supremely profitable.

–With reporting by Jeanne McDowell/Los Angeles