The Dow Jones Industrials (DJINDICES:^DJI) had fallen 66 points as of noon EDT. One key factor hitting stocks today was a government economic report showing that while personal income rose 0.4% last month, consumer spending climbed by only 0.2%, failing to keep up with price increases for the second month in a row and raising some concerns that the plunge in first-quarter economic activity might not be a one-time event. Meanwhile, second-quarter earnings season will begin in just a few hours: Nike (NYSE:NKE) kicks things off with its fiscal fourth-quarter report after the market closes this afternoon. With the athletic-apparel giant's stock having plateaued in recent months, though, some worry that Nike's high-growth phase might be heading toward its end.

Nike will issue its earnings release at about 4:15 p.m. EDT. The company has scheduled a conference call at 5 p.m. EDT to discuss the release and its financial results more broadly, with a live webcast available at Nike's investor-relations website.

Source: Nike.

Investors have mixed expectations for Nike as it closes its fiscal year, once again believing the company will post big growth in overall sales but not see any of that growth hit the bottom line. Shareholders are more confident about the Dow component's long-term earnings growth, though, with projections of 10% to 12% rises in earnings per share over the next several years.

Part of the problem is that Nike's results aren't consistent worldwide. Key geographic areas including North America and Europe have supported overall sales growth, which is particularly impressive given the disparity in economic conditions between the healthy U.S. and the struggling eurozone. Yet China and other emerging markets haven't proven to be the major drivers of long-term growth that many expected, and short-term currency issues have hurt Nike's ability to translate sales gains into higher profits.

More important, competition from Under Armour (NYSE:UAA), Adidas (NASDAQOTH:ADDYY), and other apparel makers has forced Nike to raise its game. In particular, Under Armour is small enough that it can focus in on the most lucrative areas to go up against its Dow-component rival; recently it has worked hard to emulate Nike's efforts to become more popular among customers. With signature apparel lines, Under Armour wants to encourage the same loyalty that its rival has enjoyed for decades, and that could pose a threat to Nike's future growth.

Nike will move the Dow tomorrow, and if the news from its earnings release and from the U.S. men's national soccer team at the World Cup is all good, the company's gains could inspire a flood of investor interest. Despite some competitive threats, Nike has shown in the past that it can overcome adversity and emerge as the champion of its industry.

Dan Caplinger has no position in any stocks mentioned. The Motley Fool recommends 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.