After hitting the dressing room at Chelsea Collective, the new activewear chain from Dick’s Sporting Goods, you can walk to the “girlfriend lounge” and test how your new gear feels while using a ballet barre or treadmill.  And if you’re not quite satisfied with the fit of your printed leggings or wispy workout tank, the retailer offers free alterations.

As it opened the doors to its first store on Tuesday evening at Tysons Corner Center, Chelsea Collective became the latest retailer to make a play for the booming market for “athleisure” clothes, pieces that are functional enough for a workout but stylish enough for running errands.

It’s hard to imagine this trend hitting a bigger crescendo than it is right now: U.S. sales of women’s activewear soared 21 percent to $18.5 billion in the year ending June 2015, according to NPD Group. Lululemon, the store widely credited with sparking the trend, has grown its store count by 76 percent in the last three years, while Athleta has doubled its fleet in two years. Everyone from value-conscious Old Navy to upscale designers such as Rebecca Minkoff and Tory Burch are looking to get in on the action by launching activewear lines. Even Ann — the company behind Ann Taylor, bastion of sensible office attire — is starting an athleisure chain, Lou & Grey.

And now here comes Chelsea Collective, going after shoppers’ dollars by bringing a fast-fashion metabolism to the category and a boutique-like mix of big-name and niche brands.  Its challenge will be finding its customer in an already crowded market that it has been somewhat late to enter.

Experts say that, for now, the athleisure trend doesn’t show any signs of slowing.  Retail analytics firm Editd reports that there was a 14 percent increase in the number of yoga pants available to buy on the U.S. womenswear market in June 2015 compared to June 2014.  Meanwhile, the median price for yoga pants jumped from $74.21 to $87.29 during the same time period, Editd data show, suggesting that consumers are enthusiastic enough about the trend to pay higher prices for it.

Yet clothing trends are reliably cyclical and tastemakers are notoriously fickle.  And it’s hard not to look at the ubiquity of the athleisure craze and think of the flurry of other items in recent years that have shown this much sizzle — Ugg boots, expensive denim, Coach handbags, Spanx — only to eventually cool off.

But Chelsea Collective and industry experts say athleisure is different: They see it not just a fleeting fashion trend, but a complement to a sweeping cultural shift toward healthier lifestyles.

Cubicle workers are switching to standing desks and going for walking meetings. A push for an active lifestyle has fueled big business for the likes of FitBit, whose stock is soaring after going public in June, and SoulCycle, which is gearing up for an IPO that aims to raise $100 million. The call for a healthy lifestyle is only growing, the theory goes, and athleisure clothes are designed to help us look good while we do that.

Chelsea Collective is aiming to distinguish itself in this crowded category not only with a focus on services such as the “girlfriend lounge,” but by refreshing its merchandise every two weeks to make sure customers are constantly seeing fresh pieces that reflect of-the-moment trends.

“The demographic that we have in mind is somebody that is really on the cutting edge of both fitness trends and fashion trends.  So somebody who really likes to try things,” said Lauren Hobart, general manager of Chelsea Collective.

In other words, they’re looking for shoppers like Anne Mauney, a dietician and food blogger who was invited to the store opening on Tuesday and swooned over the printed leggings and sheer tanks.

“I’m a big fan of the workout-brunch combo,” Mauney said, adding that these clothes could easily take her through such a day.

Chelsea Collective also believes it stands out from other specialty athleisure stores by carrying multiple brands, including Nike and Under Armour as well as under-the-radar labels such as Lorna Jane and Lole. It also includes a wide range of sneakers, which are not sold at Lululemon.

Liz Dunn, chief executive of retail consultancy Talmage Advisors, said Dick’s Sporting Goods may be onto something by spinning off a separate chain.

“One of the things that’s emerged from this whole women’s fitness trend is the fact that women were not that happy with the traditional sort of big-box shopping format for athletic apparel,” Dunn said.

And yet Chelsea Collective will have serious hurdles, too, as it tries to connect with customers. It is late to the athleisure wars, so it will have to fight hard for market share, and it remains to be seen just how long shoppers will clamor for these types pieces.

Athleisure “probably has two or three years” before it loses some of its cool factor, said Ellen Sideri, chief executive of trend forecasting firm ESP Trendlab.  That doesn’t mean the aesthetic will go bust: Sideri says that many shoppers will likely just come to think of pieces made from performance fabrics as a ho-hum wardrobe basic instead of a must-have trend item.

Some analysts and experts also expected Chelsea Collective to try to distinguish itself from the likes of Lululemon by offering lower prices.  And while it does have some more affordably priced pieces, such as Calia by Carrie Underwood leggings for $60, Chelsea Collective has plenty of pieces with price points similar to Lululemon, such as $95 Nike Legend tights, a Moving Comfort sports bra for $58 and a Spiritual Gangster zip-up hoodie for $98.  That may make it more difficult for the upstart to separate itself from its more established rivals.

A second Chelsea Collective outpost will open in Pittsburgh in about two weeks.  The company says they’ll be closely watching their performance to determine whether and how to expand the concept further.

In the meantime, Dick’s executives are trying to make sure they don’t miss out on the women’s athleisure trend in their flagship fleet, either.  They’ve taken away floor space from fitness bikes and golf equipment in Dick’s stores to offer more women’s apparel.

“Women’s athletic apparel has become such an amazing growth area that we really feel like there’s multiple different ways to serve this customer,” Hobart said.