Unless you've been living under a rock in recent years you'll know that when it comes to the world of fitness, HIIT is where it's at these days.

Hours spent jogging on the treadmill have been replaced by high intensity interval training sessions, and while so many of us consider ourselves converts, it turns out we're not quite as clued up as we think we are.

Creative manager of group fitness at Equinox, Rachel Vaziralli, recently explained that while fitness fanatics are, indeed, lunging, squatting and jumping like good things, they aren't taking the intensity of their regime into account.

With many gym-goers boasting that they can endure 60-minute HIIT sessions, Rachel is here to tell them that if they're still exercising after an hour, they're not working hard enough.

"If you can go longer than 30 minutes, you weren’t actually working hard enough,” she told Well and Good. "The whole point is to push to unsustainable intensities."

In other words, if you put enough effort into your session in the first thirty minutes, there is no need to push past that limit (not lest because you shouldn't be able!)

Commenting on those who supposedly extend HIIT sessions, Rachel insists that there's little to be gained from the endeavour.

"What happens is your body just adjusts, so you hold back on the intensity,” Rachel explains. “You’re spending more time than [necessary] for the same results.”

So, if you're determined to become a HIIT aficionado, it's worth remembering that pushing yourself to the limit in the first 30 minutes is the name of the game.

Anything after that is eating into Netflix time…