Lululemon's website features this startling photo - and there's a brilliant reason why

Lululemon is heavily pushing its men's products, and that's paying off.

On Wednesday, the company said sales for its first quarter rose 17% to $496 million. Sales of men's clothing outpaced that, rising 21% from a year earlier.

On the conference call to discuss earnings, Lululemon's executives encouraged investors to visit the company's webpage. Once there, they were greeted by the image above, a hearty promotion of its ABC ("anti ball crushing") pants.

Typically, the company pushes its women's apparel first, but Lululemon has been talking up the men's business for a while now. It opened a dedicated men's store in New York in 2014, and said it planned for men's products to reach $1 billion in revenue by 2020.

It doesn't break out men's sales as a proportion of the total, but revenue of that amount would be a boon to Lululemon's overall sales - currently just over the $2 billion mark.

This is hugely important, because even though Lululemon pushes its innovation and new products, in order to truly surpass rivals like Under Armour, it needs to appeal to more than just its core customer base of women.

It's particularly important because Under Armour is coming after Lululemon's female customers. Under Armour CEO Kevin Plank has said he wants to make Under Armour's women's division "at least as large if not larger than our men's business."

If Under Armour's women's sector did, in fact, increase to the size of its men's sector, it would completely usurp Lululemon.

Of course on this front, a brand that gained popularity as a women's' yoga wear company, "has a lot more work to do in building its brand image with male shoppers," Neil Saunders, CEO of consulting firm Conlumino, wrote in a recent note to clients.

That doesn't mean that Lululemon is wrong to go after the men's market, Saunders wrote.

"The expansion into menswear is going reasonably well and there is no doubt that Lululemon is gaining ground in this space, however our view is that given the embryonic nature of this part of the business growth is slightly soft."