BY AUBREY YEO

The comfort and maneuverability of sportswear used to be devalued by the opportunity cost of style – it was a time when activewear seemed to exist in a different dimension from the realm of fashion.

But the "athleisure" revolution has blurred those lines in recent years and created a world in which Stan Smiths have ascended from humble Adidas tennis shoes to style icons – the same world that now hosts the ubiquity of Lululemon Athletica on college campuses.

Fashion brands have been quick to jump on the trend as we see activewear collections, filled with sweatpants, hoodies and leggings, become a mainstay in clothing lines released by European fashion giants H&M and Zara.

Designer labels have also taken the plunge into this trend, with designer Alexander Wang professing his love of activewear to The New York Times about a year ago.

“I live in gym clothes,” Wang said. “When you go out on the street, it’s the uniform now.”

The athleisure movement has also managed to effect change in the reverse direction, with sporting goods powerhouses like Nike and Adidas reimagining their classic sportswear designs into fashion must-haves through collaborations such as NikeLab between Nike and Japanese label Sacai, and Adidas' collaboration with Moschino's Creative Director Jeremy Scott as well as celebrities Kanye West and Rita Ora.

And consumers are loving it. Jeans – the once-classic casual outfit staple – saw a decline to $16 billion in domestic sales in the 2013-2014 fiscal year, while the activewear industry continues to explode with revenue, bringing in double that number at $33.6 billion that same year. Based on these figures alone, it’s a no-brainer why many within the apparel industry are jumping on the athleisure bandwagon.

So the next time you see someone with joggers and a pair of Nike Flyknits, they might be headed to the gym to get a cardio fix. But who knows, maybe that person could just be headed to class.