As you may have noticed on your Instagram feed of late, there’s a new contender in the world of high-intensity fitness classes. “Boxing is the wave now,” says Mr Noah Neiman, who until recently was a Barry’s Bootcamp master trainer. Admittedly, the improbably chiselled Mr Neiman is more than a little biased: he is a co-founder of Rumble, New York’s hit new group boxing studio that, with its lighting and sound system, could be described as Fight Club meets night club. Except the first rule of Rumble is that you do talk about it. The second rule seems to be that you don’t wear your shirt very often.

In New York, Rumble is duking it out with fellow challengers Shadowbox, Gotham Gym, Overthrow. Meanwhile London’s Kobox, which boasts locations in Chelsea and the City, is reportedly sizing up five locations in NYC. And heavyweight champion Mr Anthony Joshua is involved in BXR, a slick new boxing studio that has just opened in Marylebone.

The boxing boom is part of the explosion in pay-as-you-go boutique fitness classes which have turned the traditional (and underused) annual gym membership on its head. “Classes in general have seen a surge in popularity over the past five years,” continues Mr Neiman. Boxing isn’t new, of course. In fact, it’s one of the oldest and noblest of disciplines, dating back at least as far as Ancient Greece, where it was part of the Olympic Games. But where has this new boxing class craze suddenly sprung from?

Mr Miles Teller in Bleed For This (2016), Mr Michael B Jordan in Creed (2015) and Mr Jake Gyllenhaal in Southpaw (2015) have recently revived Hollywood’s long-standing obsession with boxing. And after a few years on the ropes with UFC surging in popularity, the sport itself has made a comeback of late. Mr Joshua is partly responsible for this and he has the biggest fight of his career coming up against Mr Wladimir Klitschko at Wembley next month. And after endless speculation, it now seems like the unbeaten Mr Floyd Mayweather will come out of retirement to fight UFC’s Mr Conor McGregor.

But mainly, the boxing boom has come about because it’s an incredibly effective full-body workout that gets you in shape fast. With its three-minute rounds, boxing was effectively high-intensity interval training (Hiit) before it was cool. Plus, hitting things is a handy way to let off steam and unload stress while simultaneously burning calories, and is more engaging than mindlessly plodding on a treadmill. Boxing has the added benefit of feeling masculine, and it makes you feel good as well as look good. “For guys, boxing has an inherent cool factor that makes it much more acceptable as a form of group fitness than, say, spinning, Pilates or yoga,” says Mr Neiman.

Boxing fresh? Don’t worry: the instructors will show you the ropes – and there’s no contact involved. But if you’re some way from fighting fit, some sprints and interval runs beforehand will help you go the distance.

These classes often incorporate old-school exercises like press-ups, sit-ups and burpees. But Kobox ups the difficulty with a TRX suspension trainer (which Mr Joshua uses). Float like butterfly, sting like a b****.

“The only way to get better at something is to do it,” says Mr Neiman. “If you put the reps in, you will progress, and that’s the driving force of happiness.” You’ll be richer than Money Mayweather – emotionally.