Eco-friendly fabrics

From soy to bamboo and coconut to polylactic acid, staying green in the gym will be easier than finishing all those reps. "Many of the eco-friendly fibers showing up in exercise clothes are also moisture-wicking, quick-drying and naturally resistant to bacteria, which helps prevent odors," Detz says.

Try these eco-friendly lines: ActiveSoy, Nau and Champion's Vapor

ActiveSoy pullover hoodie, $42 at Gaiam.com

Skorts and dresses

Who wants to slip out of that cute dress in favor of an old pair of gym shorts? Now you don't have to. Slip into a running dress next time you hit the track. "Go to any major race in the U.S. this spring, and you're going to see a lot of women running and biking in skorts and dresses," Detz says. "They're feminine, cute and provide a little added butt camo that we all like."

Try these looks: Brooks' running skort, SkirtSports.com's BikeGirl skort

Running dress by New Balance, $70. Newbalance.com for retailers

Yoga-inspired clothing

Madonna may have created the buzz about yoga, but it's Cameron Diaz who has made yoga look so good. "Yoga styles have had a big influence on fitness fashion. People are wearing the pants and tanks originally designed for the studio to run, lift weights and go to lunch," Detz says. "And clothing manufacturers are responding by mimicking the yoga style in their fitness clothes."

Try these yoga-inspired lines: Lululemon Athletica, Prana, Sivana Spirit

Groove pants by Lululemon Athletica, $84. Lululemon.com for stores

Sun-protective clothes

Stop using the sun's harmful rays as an excuse for sitting on the couch instead of pounding the pavement. "Manufacturers have started treating fabrics with UPF solutions so your shirt, pants and hats may have sunscreen built into them," Detz says. "If you run, walk, bike or hike, these clothes are going to make your life a lot easier." Look for fabrics that have UPF 50, which means they block 98% of the sun's harmful UV rays.

Try these looks: Columbia's hats, Royal Robbins' hiking pants

Quadro Flow run top by ASICS, $38 at Asics.com

Celebrity fit club

Celebs are sharing their fitness fashion faves with gymgoers everywhere. Here's a taste of their glam gear:

Serena Williams for Nike

The tennis ace has teamed up with Nike to share her style secrets and add some couture to the courts. She's got you covered from head to toe with shoes, skirts and tanks - but she can't help you with your actual game. (Maybe a bow-adorned dress or metallic skirt will intimidate your opponent enough.) $50-$105, available at Nike.com

Kelly Ripa for Ryka

This super-fit superstar is taking her morning sass to the gym. Starting in August, workout wunderkinds will be able to snag the apparel and shoes Ripa is helping design. While maintaining Ryka's tradition of designing simple, comfortable gear, Ripa will add her own flair to the shoes and apparel. $45-$100, available at Rykashop.com and Lady Foot Locker stores nationwide beginning in August.

Stella McCartney for Adidas

McCartney has continued to build and refine her fitness line for Adidas since its introduction in 2005. Her latest addition: dance and golf gear. This is not your mom's workout gear - McCartney draws inspiration from her own ready-to-wear collections. $50-$250, available at Shopadidas.com

Scarlett Johansson for Reebok

The starlet looks as good in red-carpet attire as she does in sneakers and a T-shirt, so she was a natural fit to co-design a fitness line with Reebok. Her collection, Hearts, is a throwback to retro workout wear. Think off-the-shoulder sweatshirts and '70s-inspired shoes. The ultra-girly line also features henleys and hoodies to wear to the gym or running errands. $39.99-$119.99, available at Store.reebok.com