The athleisure trend has been so prominent in 2016 that the Merriam-Webster English dictionary has included the word in its latest edition, defining it as "casual clothing designed to be worn both for exercising and for general use."

Several factors have contributed to making workout gear a must in 2016 and, as market research firm NPD noted in October, activewear still remains a significant market, despite reports saying that the athleisure trend has now peaked. At any rate, here is a list of the main elements that have made athleisure an international success.

Leading fashion designers

While Adidas and British designer Stella McCartney have been working together for some time, several other labels have hit on similar collaborations. Nike has called on designers Riccardo Tisci (Givenchy) and Olivier Rousteing (Balmain); Rihanna introduced the Fenty x Puma collection at the Paris Fashion Week; Bodyism, the fashion models' favourite brand, has collaborated with Charlotte Olympia, and Beyoncé has launched her own sports apparel collection, Ivy Park.

Famous fans

Aficionados of fitness-crazy celebrities will have not failed to notice their favourite stars’ everyday looks on Instagram and on the pages of glossy magazines. Away from the runway or the red carpet, celebs such as Gigi and Bella Hadid, Kendall Jenner, Rosie Huntington-Whiteley, Reese Witherspoon and Alicia Vikander proudly show off their yoga gear, even when they are not heading for a gym session.

Niche labels

Fitness fans now have a wide range of options to choose from: besides sports brands such as Nike, Adidas and Reebok, a spate of niche and luxury athleisure brands have cropped up to satisfy their demand. These labels too use tech fabrics and performance materials, but are distinctive for the cut and style of their models. For example Aeance, which features a single, non-seasonal collection to be worn both at the gym and out on the town, or the lifestyle and fitness brand Tone It Up, which created a capsule collection with Bandier, and P.E. Nation, which combines fashion with functionality.