Under Armour just exposed a weakness in its women's line

Under Armour has been investing heavily in its women's business.

The company has snagged high-profile endorsement deals with female athletes and supermodels, including ballerina Misty Copeland and model Gisele Bündchen, and last year launched its biggest ever global women's marketing campaign.

Under Armour is hoping the investments will grow its women's segment, which generated about $600 million last year, to at least the size of its core men's business. The company's total revenue in 2014 was just over $3 billion.

But Under Armour's presentation of the women's line in stores has failed to live up to the advertising, CEO Kevin Plank told analysts during a conference call Tuesday.

"We don't believe we played our best game yet," Plank said. "We don't think when you walk into a store you're getting the best version of Under Armour yet."

In addition to improving its merchandising, the company also needs to offer more clothes for women to wear outside the gym, Plank said.

Under Armour built its women's business off the popularity of its compression shorts and sports bras, he said.

Now the company needs to "be more relevant beyond just strictly in the gym or what she is wearing beneath."

"I think you'll see Under Armour continue to take those steps towards being more relevant in more aspects of her life," Plank said.

He said Under Armour's newly acquired fitness apps should help the company better communicate with and understand its female customers.

Under Armour recently bought several apps, including MyFitnessPal, MapMyFitness, and Endomondo for $710 million. Plank says the apps now have 130 million users combined, more than 60% of whom are women.