The massive wave of success that athletic apparel, footwear, and accessories manufacturer Under Armour (UAA 2.79%) is currently riding shows no sign of stopping anytime soon. The company's first-quarter earnings results prove that Under Armour is the best high-growth investment in the industry, easily beating out peers like Nike (NKE 0.18%).

In yet another quarter, Under Armour has beat the average analyst estimate and raised guidance, proving that it is one of the best-performing companies in the world right now, and truly worthy of its seemingly expensive valuation.

Source: Company Facebook 

Blowout earnings, yet again
It seems like every quarter, I'm writing the same thing about Under Armour: The company crushed earnings estimates on both the top and bottom lines. Reported revenue of $642 million soared past the Yahoo! Finance consensus estimate of $598.81 million, and even the high estimate of $618.28 million. Reported diluted earnings per share of $0.06 easily bested the consensus estimate of $0.04, and matched the high analyst estimate.

On a year-over-year basis, the company's revenue grew a staggering 36%, while diluted EPS grew at an even faster 71%. Net income also increased 73%, to $14 million, compared to $8 million in 2013's comparable quarter.

Highlights for the company in the first quarter include 33% growth in Under Armour's signature apparel segment, which generated $459 million in the quarter. Growth was driven primarily by the addition of new product releases in categories like golf, hunting, training, studio, and basketball.

The company's once-struggling footwear category performed even better, growing revenue 41%, led by the company's new and well-received running shoe SpeedForm Apollo. While the segment only generated $114 million in the quarter, this remains an important area of growth for Under Armour, especially if the company truly wants to challenge Nike on the global stage.

Nike's latest innovative footwear offerings, notably, the revolutionary soccer boot Magista that is set to release just in time for the 2014 FIFA World Cup in Brazil, demonstrate just how much of a lead the company has on all competitors in the space. With a game-changing product, support from high-profile soccer athletes like Andres Iniesta and Mario Gotze, and a massive global footprint, Nike is set to market to the world its latest flagship sneaker and create even more brand awareness among consumers.

Raising the bar, once again
However, the good news for investors extends beyond Under Armour's prior performance. The company also raised guidance for fiscal 2014. Management now expects net revenues to be in a range of $2.88 billion to $2.91 billion, which represents growth of approximately 24%-25%. Operating income for the year is also now expected to be in a higher range of $331 million-$334 million, which represents growth of 25%-26%.

For comparison, according to Yahoo! Finance, analysts, on average, expect Nike to grow revenue 9.5% in the year ending May 2014, and 8.7% in the year ending May 2015. While Nike is a much-larger company with already enormous revenue-generating capability, which makes it more difficult to grow at robust rates, the disparity in growth projections between the two competitors should highlight two things for investors: The first is how massive Under Armour's success is expected to be going forward; the second is the potential size Under Armour could grow into if it ever truly matches Nike on a global stage.

Currently, the Baltimore-based company has a market capitalization of $11.5 billion, which is dwarfed by Nike's $65 billion. Under Armour is also expected to generate only $2.9 billion in 2014 compared to Nike's $30 billion in fiscal 2015.

Founder, Chairman, and Chief Executive Officer Kevin Plank concluded:

This strong start to 2014 illustrates the unlimited potential that still lies ahead for our Brand, whether it is today's opening of our Brand House in New York City or our product hitting shelves for the first time in Brasil. Through the lens of our global Brand Holidays and leveraging our diverse array of sports marketing and Connected Fitness assets, we are well positioned to tell these stories in new and powerful ways."

The only downside to Under Armour is the company's expensive valuation. The company's forward P/E of 46.5 is significantly more expensive than Nike's forward P/E of 21.9.

(Source: Company Facebook)

Foolish bottom line
All indicators point to continued success for Under Armour going forward. The company is excelling in all product categories, and investors are reaping the benefits, as shares are up almost 100% in the last year alone. With management showing no signs of taking its foot off the throttle, investors should follow suit and hang on to shares of Under Armour for the long term.