Under Armour's quarterly revenue jumped nearly 28 percent, driven by strong demand for its basketball shoes endorsed by NBA star Stephen Curry.
However, sales growth in the company's apparel business, its biggest, dropped below 20 percent for the first time in more than seven years.
Under Armour has been expanding its apparel business, which accounts for nearly two-thirds of total revenue, by adding more "athleisure" clothing - a term for daily wear apparel inspired by exercise outfits.
Fashion model Gisele Bundchen and ballerina Misty Copeland are among the celebrities the company has signed to endorse its "athleisure" lines.
Under Armour's apparel sales rose 18.9 percent to $612.8 million in the second quarter.
Footwear sales surged 58 percent, helped by demand for basketball and running shoes.
"The Stephen Curry signature line has continued to drive strong momentum for the brand and our pinnacle football product, the Highlight Cleat, continues to lead the market." Chief Executive Kevin Plank said in a statement on Tuesday.
Net income, however, plunged 57 percent to $6.3 million in the quarter ended June 30.
Under Armour reported earnings of 15 cents per Class C share and a loss of 12 cents per Class A and Class B share, compared with a profit of 3 cents per share, a year earlier.
Excluding items, the company earned 4 cents per share.
Revenue surged to $1 billion from $783.6 million.
Analysts on average had expected a profit of 1 cent per share, according to Thomson Reuters I/B/E/S.
Under Armour also maintained its full-year sales forecast of $4.93 billion, which translates into a growth of 24.3 percent, the slowest in six years.
The No.2 U.S. sportswear maker's shares were little changed at $43.50 in premarket trading.
(Reporting by Subrat Patnaik in Bengaluru; Editing by Kirti Pandey)