After years of rapid growth, Under Armour has no plans this year to jump into new businesses or look for new U.S. retail partners to sell its products. Instead, this is a year to step back and reset.

That message, delivered Thursday by Under Armour CEO Kevin Plank, came as the Baltimore-based brand announced its first quarterly loss since it became a public company in 2005.

The loss was smaller than expeceted, sparking a rally that sent Under Armour’s stock up nearly 10 percent to $19.82 a share, but reflects significant challenges to its maturing business. Sales growth has slowed amid the closures of key retailers and tepid demand for its athletic wear.

Plank reassured investors during a conference call that the company is addressing the abrupt slowdown, focusing on better management and improving product offerings, including more fashionable, yet functional, clothing that can be worn outside the gym or off the field.

“I’m really giving my team the ability to just relax and just focus on what we have right now and becoming excellent in every category,” Plank said during a conference call. “As far as our brand goes... I truthfully wouldn’t change positions with anyone else in the world, with any other brand. Our brand demonstrates that we can take punches, and I believe that our brand also demonstrates that it can throw them too.”

While sluggish for Under Armour historically, sales continued to grow, up 7 percent to $1.1 billion. Plank noted that means more people are buying Under Armour products this year than last.

To keep them coming back, the brand plans new products in its footwear and lifestyle categories, including a retooled Stephen Curry signature basketball shoe, a new lifestyle collection called Unstoppable, and a women’s lifestyle collection inspired by endorser and ballet dancer Misty Copeland.

Such offerings are an attempt to boost a brand that may be losing some relevance.

Under Armour landed among a list of brands losing share or relevance in Piper Jaffray’s Taking Stock with Teens Survey, released earlier this month, joining Michael Kors, The North Face, Ralph Lauren and Vineyard Vines. Under Armour ranked fourth among preferred athletic apparel brands, after Nike, Adidas and Lululemon.

Under Armour has struggled to do one thing that rivals Nike and Adidas have done better.

“They’re able to bridge that performance and lifestyle category very effectively,” said Howe Burch, president of Baltimore advertising firm TBC. “Under Armour has been so strongly positioned in the performance space, they’re finding it challenging to translate their brand into the lifestyle space.”

Under Armour also is enduring the typical ebb and flow that most brands experience, he said.

“Every brand... has gone through that period where their brand is on fire, and then it’s not so in favor anymore,” he said. “They’re starting to feel that a little bit. Adidas is the hottest brand going right now, and two years ago you couldn’t give Adidas away.”

Under Armour needs to broaden its approach to innovation beyond the technical aspects of products, said Sam Poser, a senior footwear and apparel analyst for Susquehanna Financial Group.

“Innovation goes beyond ‘Does that material wick moisture better than the old one?’?” Poser said. “Is it really something new that compels the consumer to go buy a new one?”

The brand also is struggling with fallout from last year’s bankruptcy of The Sports Authority, which catered to sports-minded consumers. It’s unclear how Under Armour’s move this spring into discount department store Kohl’s will play out, Poser said.

“I’m less concerned about the first quarter than longer term,” Poser said. “The bigger story is what the sales growth is going to be. The size of the U.S. market is only so big.”

Other analysts said they were encouraged by the direction of the company, which has lost about half its stock value over the past year.

In a report Thursday, D.A. Davidson & Co. analyst Andrew Burns called Under Armour an attractive investment,” saying he believes it’s poised to return to being the fastest-growing brand in athletic apparel.

Under Armour called the results a “solid start” to the year. The brand reported a loss of $2.3 million, or a penny per share, when adjusted for currency exchanges. Analysts were expecting a loss of 4 cents per share.

The company maintained its outlook for the year, reiterating that annual sales are expected to grow 11 percent to 12 percent to nearly $5.4 billion. Before the end of last year, Under Armour had reported quarterly gains of 20 percent or more for nearly seven years.

Sales during the first quarter were driven by a 13 percent gain in online and branded store sales, while sales through retailers slowed. U.S. sales were down 1 percent. International sales, expected to generate much of its future growth, accounted for a fifth of revenue and jumped 52 percent.

lmirabella@baltsun.com