Under Armour founder Kevin Plank is stepping down as CEO

Under Armour is making changes at the top as it continues to struggle against its rivals.

Current CEO Kevin Plank is resigning and will be replaced by Chief Operating Officer Patrik Frisk will assume the position on January 1, 2020, the company announced Tuesday.

Plank, who has served in the CEO role since the company's founding in 1996, will serve as an executive chairman and brand chief.

Plank called Frisk the "right person" to be Under Armour's CEO in a release.

"As my partner during the most transformative chapter in our history, he has been exceptional in his ability to translate our brand's vision into world-class execution by focusing on our long-term strategy and re-engineering our ecosystem through a strategic, operational and cultural transformation," Plank said.

Frisk said he's "honored to lead this great brand toward the realization of its full potential." He's been with the company since 2017.

The changes come amid the company's struggling North American sales. In its most recent earnings report, Under Armour's sales in the region declined 3% compared with a year ago.

Under Armour's business with outside retailers and its direct sales through its own website and stores both fell last quarter in the US. Under Armour also lowered its forecast for the region, signaling that the brand expects struggles to persist.

It's also having trouble attracting customers in North America, as Nike, Adidas and smaller brands such as Fila and Puma thrive, Cristina Fernandez, analyst at Telsey Advisory Group, previously said in a note to clients.

Plank is the most recognizable face of the company. Plank defended Under Armour's hometown of Baltimore against President Donald Trump when he criticized the city over the summer.

But he's also been embroiled in scandal. The Wall Street Journal reported Plank has been soliciting business advice from MSNBC anchor Stephanie Ruhle, which made some employees uncomfortable.

The same newspaper also reported on the company's culture last year and revealed a practice that had allowed employees to charge strip club visits to their corporate cards. According to the article, executives and employees, including Plank, attended strip clubs with athletes and co-workers over the years.

Plank and Frisk co-wrote a letter to employees and admitted the story was "tough to read."

In a statement, Under Armour aid it has "addressed these serious allegations of the past and will continue to address workplace behavior that violates our policies."

The stock is only up 12% for the year - a steep decline from its highs in July when it was up as much as 50% for the year. Shares are moving 2% higher in premarket trading.

& 2019 Cable News Network, Inc., a WarnerMedia Company. All rights reserved.