Gelband is most famed for sculpting the bodies of Miranda Kerr, Candice Swanepoel, Irina Shaik, Karlie Kloss, and Martha Hunt.
Justin Gelband, a New York-based celebrity personal trainer and cofounder of the cult gym modelFIT, is most famed for training Victoria's Secret models, including Miranda Kerr, Candice Swanepoel, Irina Shaik, Karlie Kloss, and Martha Hunt.
He recently crossed the pond to undertake a summer residency at BXR London, a luxury boxing gym in Marylebone.
But during his visit to the English capital, he was left unconvinced by one exercise fad overtaking the city's fitness scene: HIIT.
HIIT stands for high-intensity interval training. The technique, which combines cardio with resistance training, relies on quick, all-out bursts of energy. This means each HIIT session is tough but shorter than traditional workouts. A viral 7-minute exercise routine, for example, is based on HIIT.
Gelband, now back on home turf, told Business Insider that "killing your body is not the way to train."
"London is behind and it really needs to wake up," he said. "People who are sitting at a desk all day — their bodies are different. They have not been taught how to handle cross fit style classes of burpees, deep lunges, kettlebells and so forth — it is very scary."
Exercise is a personal thing that needs to be built around the individual and their lifestyle, Gelband believes.
The 44-year-old started his career helping women who were between 40 and 60 kilos overweight (90-130 pounds) to lose the extra pounds in a "sustainable way." It takes between a year and a year and a half, he says.
"There's no quick fix. It's a lifestyle change."
"When you come into my gym I'll spend an hour and a half analysing you from your posture, your form, coordination, past injuries, lifestyle, genetics. I'll make you take off your shoes to see how you walk, how you pick something up. The analysis goes so deep."
"You shouldn't just go into a class where someone is reading from a piece of paper — that doesn't make any sense to me. I don't want to hurt anyone. I would prefer that in a class of 15 people, 13 were mad that I didn't go hard enough than two people got injured."
Gelband has been perfecting his training methods for 19 years. His famed workout focuses on the smaller muscle groups, rather than putting too much emphasis on the big. Motions are smaller and based on real-life movements, he explains.
"In real life you're not just moving back and forward, think about the rotation of your spine, pelvis, shoulder, if say you're reaching back to pass a pen to someone on the next desk."
He said that one of the problems is that people are associating exercise with pain — but they shouldn't.
"I've never felt like it was a good thing if you can't walk or move after a class. Maybe if you've just completed a triathlon or a competition, but not after a class. You should be going out to enjoy yourself after," he said.
"I mean why are women doing push-ups and burpees — unless she's rock climbing, bar lifting, or practicing a sport — why?" He added: " Oh and a walking lunge, why, when you can do a static lunge and teach them how to do it properly?"
Such high-impact training under HIIT classes can lead to longer-term conditions, according to Gelband. "When you reach 35 or 40 you're going to be hurting so bad," and this, he says, can lead to the misuse of painkillers, which can essentially spiral out of control.
If you're heading into a class with Gelband, though, don't be fooled into thinking you're in for an easy ride.
"Some people just want to throw their bodies around but people have to be ready to work with me. I always tell people if it's too easy make the resistance harder, do it for longer, or make the motion shorter and really feel the exercise properly. You need to teach people how to get there, not force them."
We have to admit, it's difficult to argue with his results.
To those who are starting out with their fitness regimes he recommends cardio all the way.
"Swimming, walking, cycling — things that are easy for the body to understand, then you can do some pilates, or yoga. The more stretches the more you feel, the better."