The next big trend in sportswear isn't about style at all

There's a new trend in sportswear - and no, it's not Lululemon's new engineered-sensation pants.

Smart workout gear is the trend in athletic apparel we'll be seeing next, reports Fortune. This clothing can track many aspects of your performance, including heart rate and calorie burn, making your workout more efficient.

Fortune points to several examples, including Ralph Lauren's PoloTech shirt, which monitors heart rate, stress level, and energy output, and Athos, which monitors heart rate, breathing, and muscle activity. There's also Physiclo, which does some work for you, too - the company's pants aid in helping you burn additional calories.

These clothes are not cheap. The PoloTech shirt, for example, sells a retail value of $295.

But there's a viable market.

Athleisure is an incredibly profitable marketplace right now, and everyone is trying to get a stake in the sector. While Lululemon and Nike are mainstays in the category, others are racing to beat them. A great way to stay ahead of the competition is to incorporate technology - which Nike has somewhat begun to do, particularly with its innovative line of new winter gear, some of which adapts to the body's moisture vapor and cools the body down.

Additionally, fitness-tracking is popular; FitBit filed to go public earlier this year.

Smart workout gear also provides a remedy for people who buy fitness tracking gear like Fitbits, but dispose of them, NPD analyst Ben Arnold explained to Fortune. He said that this sort of apparel would be "immune to fickle consumers. I always maintained that there are better places on the body like legs."

 That doesn't necessarily mean it's accurate - or that everyone is excited about the trend.

"There has been an explosion in patient-generated data, but much of it may not be useful to physicians in the short-term," Dr. Pat Basu chief medical officer at Doctor on Demand, told NPR earlier this year. "If a patient is showing me their blood pressure or heart rate they gathered from an app or device, I'll always ask myself, 'Is the fidelity of this information accurate or not?' " 

But the intersection between clothing and technology is certainly popular. Google has partnered with Levi's to make smart pants that can control one's phone.