Fabricating Fitness : Fashion: Manufacturers are choosing high-tech materials that offer climate-control benefits, improved durability, better fit and, sometimes just for fun, color changes.

A tennis player volleying in the heat of the day probably won’t know--or even care--if his Nike tennis shirt is made of Coolmax, a moisture-repelling fabric. But when he notices how dry he stays during the game, he might go back and buy another shirt.

Coolmax, developed by Du Pont, is just one of many new “performance” fibers being used to manufacture state-of-the-art activewear.

These technologically advanced fabrics take a marketing cue from today’s specialized athletic shoe business. Sports men and women are already paying up to $175 for tony shoes featuring pump gadgets and patented inner sole systems. Fiber manufacturers are betting that consumers will embrace high-tech apparel just as readily.

Some fibers, like Du Pont’s Coolmax, repel moisture. Others, like Microfine, also by Du Pont, repel wind yet allow perspiration to escape. Microfine is used in bicycle wear by Hind.

In addition to their climate-control benefits, most of these new fibers offer improved colorfastness and a better fit.

Just as celebrities have been endorsing apparel lines and tennis shoes, they are now working as spokesmen for new fibers. Tennis champ Andre Agassi, who wears Nike sportswear, is one. Cyclist Greg LeMond’s Coolmax-clad physique is featured in full-page color ads in national magazines. Triathlete Dave Scott of Hawaii also endorses the fiber.

“If your body doesn’t have the ability to breathe, your body temperature is going to rise and you’re not going to be able to dissipate heat,” Scott says, adding that he believes clothes made from the fabric enhance his performance.

Supplex is another new Du Pont fiber being used in activewear and swimwear fashions. Laurie Allyn, vice president of merchandising for five swimwear divisions of Apparel Ventures Inc.--Too Hot Brazil, Citrus, Sassafras, Cessa and Cha Cha Cha--says designers appreciate Supplex’s cotton-like look and feel--without cotton’s inherent fading problems in salty or chlorinated water. She also favors Supplex over nylon.

“These suits, made of nylon, would look too cheap and sleazy,” Allyn says, “but Supplex, with its cotton look, makes them work. It provides the needed fit and color fastness.”

Consumers should expect to pay more for these high-tech fabrics. A running top made of Coolmax would cost 50% to 75% more than one made of a typical nylon fabric, says Pete Szanto, communications director for Du Pont’s Coolmax division.

Allyn says that Supplex costs 25% to 30% more per yard than nylon, a fabric used traditionally in swimwear. She estimates a bathing suit that might cost $47 will now run “in the mid $50 range,” if made of Supplex.

Wendy Manasse Wiese, who designs swimwear for L.A.-based Catalina, is using Supplex for brightly colored solid and patterned halter-style suits. Wiese, who says she pays about $3 more per yard for Supplex than for nylon/lycra blends, says she’s not sure if Catalina customers will be willing to pay an extra $6 or so more for a Supplex suit.

“If someone is very athletic, it might make a difference to them that what they wear is made of Coolmax or Supplex, but most of the new performance fibers are for pure sports.”

Patagonia, the Ventura-based company that outfits athletes as well as exploring expeditions, has the exclusive right to Capilene, a polyester fabric that absorbs moisture easily and dries quickly. The company uses the fabric as a lining for outerwear, and for long underwear.

One of the newest clothing collections using high-tech fabric carries the Freezy Freakies label. It came about when 10-year-old Judah Rifkin suggested a line of outerwear that would go with a pair of his winter gloves, which changed colors in various temperatures. His uncle took him up on the idea, became a licensee of Freezy Freakies and started to manufacture a line of children’s jackets made from a color-treated polyurethane fabric. The bomber jackets and parkas--whose graphic designs change color when the temperature falls--are priced from $60 to $80 and sold through the J.C. Penney mail-order catalogue and in smaller specialty stores.

The color changes on the clothes are mainly for effect. But eventually, the company hopes to use the fabric for environmentally sensitive clothing that can adjust to any climate change. For example, a jacket might turn white to reflect unnecessary heat, then turn a dark color to absorb warm rays when the temperature drops.

Though many of the new fibers are reserved for sports, some are moving into moderate to better-priced non-athletic activewear.

Sunny Sport, a division of the Dallas-based Sunny South Fashions Inc., used Supplex in its spring ’90 line, and again for spring ’91. But because it is pricey, Supplex will not be featured in the summer line, explains designer Debbie Castillo.

“We save it for big seasons, fall and spring, for our active and weekend wear,” says Castillo. Though Sunny Sport was one of the first companies selected to test Supplex, it may also be one of the first to discontinue it, Castillo explains, citing concerns over a saturation in less prestigious retail outlets.

“The fabric is all over the market in a variety of price ranges--including the racks at Walmart and K mart,” Castillo says.