Why Models Are Addicted to This Fitness Trend

Nine out of 10 people who learn that boxing is part of my fitness regimen find it strange. Why would someone my size—I’m 5 feet—put on sweaty Everlast gloves and throw punches at a bag? Boxing, despite the stereotypes, isn’t just a man’s game, and as the world buzzes about boxing’s big night in Vegas this weekend, as Floyd Mayweather and Manny Pacquiao finally face each other in the ring, many women who like to box will be watching.

Some will even be in attendance. The model Adriana Lima, for one, fell in love with boxing 13 years ago after hating most other exercise, and she will be at the match with her trainer Dino Spencer. “It’s very empowering because you learn how powerful and strong you can be,” Lima says. “It’s the best exercise that exists because you can get really ripped, but not too big.”

Models like Karlie Kloss, Gigi Hadid, Chanel Iman and Joan Smalls have all been seen throwing jabs and crosses with trainers, and Gisele Bundchen joined Under Armour’s “I Will What I Want” campaign with a fierce video of her training with a punching bag.

And all for good reason. Dr. Jordan Metzl, a sports medicine doctor at New York’s Hospital for Special Surgery, says one boxing class could burn around a thousand calories. “Boxing builds full-body strength, which is super helpful for both genders, but especially for women who want to do other sports,” he says. For instance: “The risk of a woman tearing her ACL is six times more than a man doing the same sport because the angle between the hip and knee is wider in a woman. Boxing can help counter balance that by building strength to protect the knee.”

Another benefit is building up bone mass, as women have a bigger risk of osteoporosis and bone density issues than men. Sports with repetitive pounding can build bone mass, Metzl says.

Jonathan Fader, a sports psychologist who works with professional athletes, says this: “It’s super helpful for women in this sport to overcome whatever adversity they’re facing,” he says. “There’s even a benefit when you’re defeated—if you have the resilience to overcome that defeat because so much of life in anything we pursue is about how we come back.”

Women may bring some innate advantages to the sport, too. Daniel Glazer, founder of New York’s boutique boxing gym Shadowbox—which has been called the SoulCycle of boxing—says he’s noticed women are much more loyal and dedicated to fitness as a part of their daily lives. “Women have so much passion when it comes to the way they exercise, and boxing is a very passionate sport,” he says.

The model Smalls tells TIME that what sold her on it is the fact that it’s fun, too. “It’s fun to feel your own strength,” says celebrity trainer Lacey Stone, who thinks Hilary Swank’s role as boxer Maggie Fitzgerald in Million Dollar Baby jumpstarted the craze for women.

“I’ve had two children and I’m almost 34 years old, and I believe that thanks to boxing, I’m still a model,” Lima says. She mentions her trainer’s 70-year-old mother, who hits the gym every single day doing the same exercises as Lima. “Boxing, it’s just perfect.”