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Oct 22 (Reuters) - Under Armour Inc founder Kevin Plank will hand the reins of the sportswear maker to operations head Patrik Frisk, hoping a change in leadership will help battle brutal competition from Nike and Adidas in the United States.

Plank has been the company's chief executive for more than two decades, turning it into a popular name in sportswear, but struggling to generate consistent sales growth.

He brought in Frisk in 2017 from footwear and accessories company Aldo Group to help steer a turnaround plan that included store closures, job cuts and fewer promotions to bolster profit margins.

"We view his capabilities as an operator favorably, and believe the regime will have continuity from Plank's leadership," Stifel analyst Jim Duffy said.

Duffy added the change in leadership would not lead to any immediate strategy changes for Under Armour.

Frisk will continue to report to Plank, who will stay on as executive chairman and brand chief, Under Armour said.

Plank also has a majority voting control of the company as he beneficially owns all outstanding Class B common stock, which has 10 votes per share.

Frisk will take over at the start of next year and will be tasked with propping up the company's sales in the United States, where it has been introducing products such as new Curry sneaker and HOVR shoes at a faster pace to shore up market share.

In an interview with CNBC on Tuesday, Frisk said the rebound in its North America business would take time.

Shares of the company, which have risen nearly 14% this year, rose 3% on Tuesday following the announcement. (Reporting by Aishwarya Venugopal in Bengaluru; Editing by Bernard Orr and Sriraj Kalluvila)