13 Reasons To Try High-Intensity Interval Training

HIIT burns 25 to 30 percent more calories than resistance training, cycling, and treadmill running, according to a study published in the Journal of Strength and Conditioning Research. “When you’re in a moderate, low-intensity exercise state—an aerobic state—your body can keep up with the amount of activity it’s being asked to do,” explains Jacque Crockford, CSCS. “But with HIIT, you’re asking more and more and more from your body, and that comes with a lot of extra calories burned."

When you do a "sustainable" exercise, like going on a long run, your body uses less oxygen than when you push yourself to the max, as you do during high-intensity interval training.

And when you work out to the point where it's difficult to breathe (because your body is using more oxygen), your metabolism starts working at a higher level, says Jordan Metzl, MD, an exercise physician and author of The Exercise Cure.

"HIIT is super beneficial if you are trying to maximize your time and calorie burn," says Tatiana Lampa, certified personal trainer. "The max recommendation for HIIT per session is 20 to 25 minutes," and you get a LOT done in that short amount of time.

For example, in addition to burning more calories, HIIT workouts also help you burn more fat in less time than endurance activities, says BJ Gaddour, CSCS, author of Your Body is Your Barbell. That's because it causes your body to start burning fat for energy instead of carbs, research published in the journal Sports Medicine Open shows.

A study published in the journal Sports Medicine Open shows that HIIT increases your metabolism post-exercise even more than jogging and resistance training. “After exercise is over, when we’re trying to come back to a normal resting state, it takes a lot of different efforts to bring your systems back to homeostasis,” explains Crockford, “and that fires up your metabolism.” This is also referred to as excess post workout oxygen consumption, or EPOC.

As a result, you continue to burn calories after your workout, says Lampa. "Yes, even when you’re sitting at home on your couch!"

When you turn up the intensity on your workout, as HIIT does, you're making your heart work harder, says Metzl. And since this muscle (like most) becomes stronger after putting it through tough training, high-intensity interval training is very beneficial for your heart health.

And for people who are already suffering from heart issues, HIIT may actually more than double cardio fitness improvements compared to moderate-intensity workouts, reports the British Journal of Sports Medicine.

You know that eating healthy and regularly helps maintain your blood-sugar levels, but HIIT can help, too. A review of 50 studies revealed that HIIT improves insulin resistance more than steady-state exercise.

High blood pressure basically doubles your risk of cardiovascular disease. But eight weeks of 20-minute HIIT workouts, three times a week can decrease blood pressure as much as continuous exercise for 30 minutes, four days a week, reports a study published in the journal The Physician and Sportsmedicine.

“Exercise is medicine, and it can be preventative for those without high blood pressure and prescriptive for those who do have it,” says Crockford.

“Oxygen consumption is your cardiorespiratory system’s ability to efficiently use oxygen—from the heart, lungs, blood vessels, and everything in between,” explains Crockford. Just 20 minutes of HIIT four days a week can improve oxygen consumption by 9 percent over five weeks, almost the same increase as if you did continuous cycling for 40 minutes a day, four days a week, according to a study published in PLoS One.

That matters because its your cardiorespiratory system that allows you to suddenly run up the subway stairs, chase after your kid when he bolts into the street, and generally handle any surprising situation you’re thrown into.

Want to add a little burst of cardio training to your go-to weight-lifting workout? HIIT has you covered. Add a 5 or 10-minute burst to your strength training routine for all those extra benefits. "I always end my client’s session with HIIT," says Lampa. "So they can walk out of the gym burning as many calories as possible."

You might not think that it's possible to squeeze a solid strength-training session and a calorie-torching cardio workout into one quick routine, but you would be wrong, says Metzl. With interval training, you're pushing yourself as hard as you can go to accomplish as many reps as possible.

By incorporating strength-training exercises into your intervals (as well as cardio moves), you also reap muscle-strengthening benefits, he says.

If you're not quite ready for a full Tabata workout challenge workout challenge (20 seconds of work, followed by 10 seconds of rest, for 8 rounds), start with longer rest periods. “You want to slowly work your way toward a higher intensity on the work interval, and changing the rest intervals to be a little shorter is how your body will begin to adapt and become more efficient.”

Eve Overland, Carrie Underwood's tour trainer, has said that she loves to bust out interval-training moves to help the country singer get in quick exercise sessions when she's on the road and doesn't have a fully stocked gym—because, yup, you can even do interval training with bodyweight exercises.

There are also countless fitness apps to choose from (mostly for free!) that can help you fit in HIIT wherever, whenever.

Since high-intensity interval training doesn't require equipment or a gym space, it's very accessible. You can do a HIIT workout at home, while traveling, outdoors—really anywhere.

Ready to get started? check out a few WH routines:

If you're a beginner, try this HIIT workout.

Want to step it up? Try this advanced HIIT workout.