With a client list that reads like a call sheet for a magazine shoot (Irina Shayk, Elettra Wiedemann, Miranda Kerr), Justin Gelband is the go-to trainer for models with enviably slim and strong frames. Since launching his private coaching services a few years back, he’s devised a sequential workout that builds strength, motion, flexibility, and balance through an incredibly varied routine that fuses movements from Capoeira, yoga, dance, and mixed martial arts. The goal? Nothing short of sculpting “the ultimate woman,” as Gelband puts it. And he’s not messing around. Clients leap up onto rotating balls, twist into impossible poses using resistance bands, throw rounds of punches, and yank on cords suspended from above to mold muscle and whittle fat. Of course, scoring an appointment with Gelband isn’t exactly easy or cheap, but beginning Monday, the body sculptor and his crew will start teaching Model FIT classes, based on the aforementioned techniques, at Mushin Mixed Martial Arts in Union Square. Each 50-minute class is limited to 20 and taught by at least two trainers, who break up the class into smaller, more personalized groups to work on core and balance skills so it’s almost like getting a private session. Eager devotees looking to get to work on their bikini bodies post haste can book in advance and purchase packages—$50 per class or $400 for 10—to stay in fighting shape.

Mushin Mixed Martial Arts, 78 Fifth Ave., 2nd floor, (212) 656-1464, www.mushinnyc.com; Model FIT classes offered six days a week, starting April 18. To book in advance, call (908) 217-5181 or e-mail juddmandell@comcast.net.