under armour boss keeps dumping on his rivals,trashing Adidas as his "dumbest competitor" and refusing to call Nike by name. He has reason to be confident:Under Armour revenues increased 32% in the last year,and profits jumped 28% Rather than spending hundreds of millions on endorsement deals with star athletes as Nike and Adidas do, Plank is shelling out for technology, buying three fitness apps for $710 million sine December 2013