What is HIIT?

High Intensity Interval Training workouts are going to give you the best bang for your buck in terms of shredding fat and burning calories.

HIIT is a cardio session arranged as short bursts of very hard work. The whole point of high-intensity training is to kick up the intensity of your cardio. In order to qualify as true HIIT, you’ll need to push yourself to the max during every set. That’s why they’re short—anywhere from 20 to 90 seconds, typically. It’s the opposite of going for a long run where you ration your energy in order to sustain the activity for longer.

This level of intensity takes a little getting used to. To help gauge whether you’re working hard enough, fitness pros use a “rate of perceived exertion” (RPE) scale that describe effort levels on a spectrum of 1 to 10, with 10 being an all-out, balls-to-the-wall, giving-it-everything-you-didn’t-think-you-had level of intensity. So having said that…work intervals during a HIIT session should be at near like a 9.

Sound like a lot of work? That’s the idea: Working harder = higher oxygen intake = greater calorie burn. And HIIT will help you burn more calories both during and after your workout thanks to post-exercise exercise oxygen consumption, or EPOC. Studies have shown that high-intensity cardio —the kind that leaves you out of breath—raises your metabolic rate to the point where you continue to burn calories even after the session ends—as much as six to fifteen percent more. So for that 30, 60, or 90 seconds when you’re “on,” channel Rihanna and get to work work work work work.

You can do HIIT training on any type of cardio machine, outdoors or with various body weight exercises or conditioning drills. There’s no single best way, so be open minded, experiment, mix and match and see what works for you.