Fitbit is looking to a new generation for growth.

The company launched its new fitness tracker, Fitbit Ace, for children 8 years old and up on Monday. It wants to encourage children to move more. It also hopes appealing to a new audience will help it grow again.

While a device for children will open up Fitbit to an entirely new group of potential users, it is not enough on its own to help Fitbit completely reverse its losses. But it's a start — and some think it's part of a bigger shift the company is making to broaden its horizons.

Citron Research put out a bullish note Monday that suggests the stock could more than double over the next year if the company isn't bought first. Citron called out a number of new partnerships Fitbit has struck, including one for glucose monitoring with DexCom, an employee-wellness venture with UnitedHealthcare and a cloud partnership with Alphabet's Google.

This upbeat stance is a big change. Fitbit, the company that popularized wearable fitness trackers, has seen its momentum fade. Its sales have been slumping since 2016 as Apple lured consumers toward more versatile, and more expensive, smartwatches. Fitbit responded with its own version, the Versa, in April.

Last year, Fitbit represented 13 percent of market share for the wearables category, down from 22 percent the year before, according to IDC. Fitbit's revenue last year fell to $1.62 billion last year, a 25 percent decrease from the $2.17 billion it generated the year before, the company said in its annual report.

On Monday, Fitbit shares gained nearly 15 percent to close at $7.28, the company's best day since it went public in 2015. The stock has now increased 28 percent so far this year.

Some of that move may be attributed to Citron's comments, including its speculation that Fitbit could be acquired, perhaps by its partner Google.

"What was once a piñata for short sellers (since IPO) has transformed itself to one of the most underappreciated med-tech stories in the market with a balance sheet and brand equity that gives investors a tremendous investing opportunity," Citron analysts wrote in a report Monday.

But it will take time for these new efforts to prove themselves.

Fitbit's new device for children sells for just under $100. Like other Fitbit products, it tracks users' steps. It has customized alerts that encourage children to move for the recommend 60 minutes a day and sleep for the suggested nine hours a night.

"It keeps Fitbit on the tip of digital health," said Ramon Llamas, research director with IDC's devices and displays team. "I don't think this is going to be the thing that brings volumes back up to 2014-2015 levels, at least on its own, but it shows the massive transformation."

Those last two words, massive transformation, are what Llamas says characterize Fitbit as a company right now. Its children's device, Ace, he said, shows how Fitbit is no longer just targeting everyday consumers, or "Joe and Jane Smith on Main Street, USA" but their kids, as well.

Like traditional Fitbits, the Ace allows children to share their steps with others. Parents can set up a family account so they can monitor their children's activity and approve who they're connecting with.

Fitbit Ace has some other minor variations. It doesn't include calorie counters, body mass index, and other more nutrition-focused features. The goal is activity rather than diet, said Melanie Chase, Fitbit's vice president of product marketing.

"We see this as an opportunity to reinvigorate the tracker category," Chase said. "Kids are looking for something simple, durable, long battery life so they don't have to charge it every day and a small design for their wrists."

Chase said with Ace, Fitbit is trying to help reverse the trend of kids being sedentary. The company sees a need as young people are spending less time outside moving and playing and more time inside sitting and staring at screens.

Fitbit also wants to help promote healthy behaviors from childhood. Dr. Abby Allen, chief of pediatric orthopedic surgery for The Mount Sinai Health System, said anything that instills the concept of a healthy lifestyle at a young age will likely carry into adulthood.

"I cannot even begin to go into the possible benefits of (building healthy habits)," Allen said. "It would take too long."

Dr. Rebecca Unger, a pediatrician at Ann & Robert H. Lurie Children's Hospital of Chicago and Northwestern Children's Practice, echoed the idea that anything to help get kids moving is positive. However, she worries it could encourage children to multitask when they're trying to focus on homework and are distracted by the device on their wrist.