When it comes to gym clothes, are you a fitnessista or a schlub?

Many of us fall somewhere in the middle. We may splurge on a pair of compression pants designed to wick sweat and make our legs look slim. But, on top we're wearing an old, faded cotton shirt. Does it matter if you wear the clothes for an hour, stink them up and toss them in the hamper?

Experts say it does matter. Research shows there is a direct correlation between what we wear and how we perform. And sports and fitness clothiers have taken note. According to Global Industry Analysts, the $114 billion industry is expected to jump 21 percent by 2017, thanks to a rise in sports participation -- particularly among women -- heightened fashion awareness and growing gym memberships.

Sarah Wright, of Bay Point, works out at the UFC gym in Concord, Calif. on Monday, Jan. 7, 2013. (Kristopher Skinner/Staff)
Sarah Wright, of Bay Point, works out at the UFC gym in Concord, Calif. on Monday, Jan. 7, 2013. (Kristopher Skinner/Staff) (Kristopher Skinner)

Another factor driving the trend is that the lines have blurred between sports apparel and casual street wear. Now, you can find workout clothes that perform but also flatter the figure and are so comfortable you want to stay in them all day, says New York fitness trend expert Bianca Jade.

It's called transitional sportswear, and retailers such as Lorna James, Lululemon, Athleta and Adidas are cashing in with spendy essentials that reduce odors, prevent chafing and feature pockets to hold everything from keys and credit cards to clips for heart-rate monitors.

There was a time when Sarah Wright, of Bay Point, threw on any shirt and shorts to work out at UFC Gym in Concord. But, as Wright fell more in love with exercise and healthy living, she began to care about her gym attire, she says. As her waist line slimmed, her clothing budget bulged.

"If you look good, you feel good, and that motivates you to work out harder," says Wright, 21, wearing $98-compression capris with four-way stretch, a hot pink tank and matching Nikes while stretching on a yoga mat. "Now I get more excited to buy workout clothes than heels."

It's all about styling up to shape up, explains Jade, who reviews the latest fitness gear and clothing on her blog, MizzFit.com. She says there are four reasons why it matters what you wear and how you look at the gym: motivation, endurance, confidence and progress.

"If you feel a little intimidated about going to the gym, this is a way to feel more confident," she says. "Most of us get excited about wearing nice clothes, and if you like how you look, you're going to stay there longer."

Lastly, if you wear well-made, form-fitting clothes, you're better able to see and track your progress in weight loss and muscle gain, she says.

Jade is even pro-makeup at the gym, ladies. "I recommend a tinted moisturizer or concealer to hide imperfections," she says. "Gyms aren't just places to work out anymore. They're places to meet people, socialize and network. So it's important to look and feel great."

Daniel Marin, of Pittsburg, works out at the UFC gym in Concord, Calif. on Monday, Jan. 7, 2013. (Kristopher Skinner/Staff)
Daniel Marin, of Pittsburg, works out at the UFC gym in Concord, Calif. on Monday, Jan. 7, 2013. (Kristopher Skinner/Staff) (Kristopher Skinner)

Research confirms that looking the part can have a positive effect on cognitive processes. In a study last year, researchers at Kellogg School of Management at Northwestern University determined that having subjects wear a lab coat identified as a doctor's coat actually increased their performance on certain tasks because they believed doctors tend to be smart and pay closer attention.

They call it "enclothed cognition," a fancy way of saying that if you look good or at least look the part, you will perform better.

Still, not everyone sees the point in pricey clothes or pre-gym primping.

"You go to the gym to sweat and get your exercise in, not to impress anyone," says Marquis Hatcher, 20, of Martinez, wearing an oversized cotton T-shirt, basketball shorts and street tennies while lifting weights at Forma Gym in Walnut Creek.

Daniel Marin, of Pittsburg, disagrees. On a recent Friday in the late afternoon, when most people are gearing up for happy hour, Marin, a 26-year-old bachelor, is bench-pressing at UFC Gym in Concord in black shorts, an orange and black sleeveless athletic shirt, and matching Nikes.

"I like matching," he says. "It boosts your self-esteem."

And, he adds, it often attracts the attention of the opposite sex.

"I'd rather meet someone at the gym than a bar. That way, you know you have something in common. You share a similar lifestyle."