Under Armour (UA) is finally raising its shoe game, a critical piece in the company’s bid to move from an underdog to a heavyweight in sportswear.

Shoe sales increased 50 percent in the third quarter, outpacing big gains from Under Armour’s stretchy shirts and accessories. For the current year through September, footwear revenue is up 42 percent—a surge relative to the incremental progress Under Armour has made in the category in recent years.

The company launched a line of running shoes, SpeedForm, in January and has also been busy opening new stores. Under Armour now has about 118 shops, including a flagship in New York City that opened earlier this year.

Those company-owned stores are important. Under Armour Chief Executive Officer Kevin Plank said shoes account for a larger share of sales at its own stores, where they aren’t displayed next to competing products. “We are successfully making that transition from a company learning how to make great shoes into a truly disruptive voice in the global footwear market,” he said on a conference call on Thursday morning. “We ultimately believe footwear should be as big, if not bigger, than our apparel business.”

The gains, however, don’t appear to have come at the expense of Nike (NKE). The sneaker giant posted similarly impressive progress in its shoe game and still makes Under Armour’s footwear business look almost quaint.

Turns out, Under Armour’s recent success in the category has largely come from football and baseball cleats—products the sportswear maker has long done well with—rather than in running and basketball, markets with far bigger potential. At the moment, Under Armour holds only about 3 percent of the running-shoe market, according to Princeton Retail Analysis. That’s slightly more than Mizuno (8022:JP) and Saucony (WWW) and a little less than Adidas (ADS:GR) and New Balance.

(Bloomberg Businessweek)