Traditional apparel retailers are struggling. Teen brands like Abercrombie & Fitch, Aeropostale and American Eagle are downsizing and changing their strategies, while C. Wonder and Wet Seal have shut down locations. The problem? Millennials want more casual clothing.

Yoga products are worth $27 billion annually in the US. And while it's true that the number of people practising yoga – predominantly women – has increased by 20% in recent years, that doesn't explain why sales of yoga wear are up 87%. Are yoga pants set to become the next Levi's 901s?

Whether you’re finding peace in a yoga class, or sipping coffee at Starbucks, the accepted attire for men is now the same – trainers and joggers. As sportswear becomes a permanent fashion feature, Mr Porter has launched an activewear section to add a touch of casual luxury to men’s wardrobes.

Brands like Lululemon have changed how people view their clothing; they want it to withstand their hectic lifestyles while still looking good. But that doesn’t mean it has to be basic. By combining technical fabrics with high-end design, Kit and Ace wants to show that functionality can be luxurious.