Three weeks ago, shares of Under Armour (NYSE:UAA) tumbled after the athletic-apparel specialist beat expectations and raised guidance but worried investors with cautious comments regarding its expected performance for the last three quarters of 2014.

But despite Under Armour's warnings, the Fool's Steve Symington insists in the video below he isn't worried about its long-term prospects. To the contrary, Steve says, Under Armour's comments reflect perfectly acceptable by-products of its fast-growing business.

As a result, Steve recently followed through on his promise to buy more shares of Under Armour in his personal portfolio once the Fool's trading restrictions allowed him to do so. To hear Steve's full take on why he's convinced Under Armour is still a great bet for patient, long-term investors, please watch the video below.