Under Armour Inc (NYSE:UA) continues to perform incredibly well in a highly competitive sportswear environment. Second-quarter revenue jumped 34% to $610 million, and management increased its full-year revenue guidance to $2.98 billion to $3.0 billion. Shares were up more than 14% as of 11:40 a.m.

On the bottom line, net income was up just slightly to $17.7 million, or $0.08 per share. The company spent 42% more than a year ago on selling, general, and administrative expenses, or advertising.  

What's incredible is the momentum Under Armour has gained in footwear, which grew 34.2%, and international markets, which more than doubled in the quarter. Both are fairly small percentages of revenue, but as the company grows in these businesses, they'll provide further upside.

Under Armour shows no signs of slowing down, and the increase in full-year guidance predicts that performance will continue. The stock isn't cheap at 52 times forward earnings estimates, but sometimes, investors need to pay up for great companies.

Travis Hoium manages an account that owns shares of Apple. The Motley Fool recommends Apple and Under Armour. The Motley Fool owns shares of Apple and Under Armour. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.