There must have been a competition over the last two years among sportswear companies like lululemon athletica (NASDAQ: LULU), Nike (NYSE: NKE), and Under Armour (NYSE: UAA) (NYSE: UA) to publicly set aggressive sales goals for the next few years. At this point, both Nike's and Under Armour's targets look out of reach, as sales growth at each has slowed down in recent quarters.Lululemon, which said it intended to double its 2015 sales to $4 billion by 2020, could be in the same boat.