Devaney Devoe, a product marketing manager who lives in the West Village in Manhattan, is desperate to get into a class at Forma Pilates, the Los Angeles Pilates studio that recently opened its first New York outpost, in SoHo. A 55-minute group class at Forma costs $US75 ($105).

“Hope I get to try a session with you someday,” Ms Devoe, 26, commented below an Instagram post of Forma Pilates owner Liana Levi. She requires a referral, through Instagram, text or email, to get into a class at any of her four studios. (In the absence of a referral, Ms Levi will let someone attend class if they share a few Instagram friends in common.)