Last week, Nike (NYSE: NKE) released its 2014 first-quarter results, stunning the markets with an 8% increase in operating revenue and a 37% jump in earnings per share. Kaboom. The market ate it up and the stock jumped almost 6% on the news. Meanwhile, in Baltimore, poor old Under Armour (NYSE: UA) only managed a 160% increase in earnings per share in its last quarter. Talk about a weak showing.

Wait. What?

Everyone wins
For a pair of companies that focus on outfitting groups that compete against each other, it looks like everyone is winning. Nike and Under Armour have both easily beat out the S&P 500 year to date, with Nike up 40% and Under Armour up 70%. Under Armour's big jump began in mid-July, when it announced a stellar first quarter.

In truth, both companies are doing great things. Nike has been expanding its training, running, and -- by way of its Converse brand -- casual lines. All saw growth last quarter, and the company also managed to boost income in all its geographic divisions except China. Under Armour has released new, innovative lines this year, and growth in those products and in its footwear division has driven the whole company higher.

Drivers of growth
There are two underlying drivers of the growth. First, global demand for sporting goods is on the rise. PricewaterhouseCoopers has estimated that global sporting revenues will climb at 4% annually for the next few years, reaching $145 billion in 2015. The growing market is looking to Nike globally, and both Nike and Under Armour domestically, to provide the gear we need to play.

The second driver is domestic, and is the rise of women's sports in the U.S. lululemon athletica (NASDAQ: LULU) has benefited from this growth. In its last quarter the company increased revenue by 22% and year-over-year comparable store sales by 8%. Business has been booming due to the increased interest in sports from women in the U.S. A recent study found that revenue for women's licensed apparel -- Tim Tebow shirts and the like -- has grown 148% over the last five years. In addition, the U.S. market for yoga has risen to more than $25 billion annually. That's a market dominated by women.

The combination of global demand and domestic diversification is giving everyone a reason to shout and everyone a reason to succeed. Under Armour has been expanding its women's training line, Nike is rejuvenating its Converse brand, and Lululemon is growing in spite of product shortfalls and recalls earlier this year.

While it's nice to think that you can pick the winner, I think all three companies offer something for investors. Lululemon and Under Armour are both growing quickly, but also cost more on a price-to-earnings basis. Nike has proven its solid strength and global potential, and a turnaround in China could boost earnings even higher. It's also cheaper. Right now, if I were forced to pick just one company, I'd invest in Nike. If you've got the resources, though, check out all three.

Investing globally
Nike is just one  business that has its roots in the U.S. but has moved out into the wider world to make its fortune. Profiting from our increasingly global economy can be as easy as investing in your own backyard. The Motley Fool's free report "3 American Companies Set to Dominate the World" shows you how. Click here to get your free copy today.

Fool contributor Andrew Marder has no position in any stocks mentioned. The Motley Fool recommends lululemon athletica, Nike, and Under Armour. The Motley Fool owns shares of Nike and Under Armour. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.