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What Is HIIT? How HIIT Ignites Max Calorie Burn

High-intensity interval training or HIIT is a training method involving repeated bouts of high-intensity effort followed by a specified low-intensity recovery phase. Start a HIIT routine by alternating short bursts of intense exercise with brief rest periods.

12 min readAugust 3rd, 2023
SLWritten By Sara Lindberg
AWWritten By Ashley Walton

If you’re ready to boost your fitness level, torch calories, and improve muscular strength and endurance all in a short amount of time, then consider adding high-intensity interval training or HIIT to your overall routine.

High-intensity interval training or HIIT is a training method involving repeated bouts of high-intensity effort followed by a specified low-intensity recovery phase.

The work and recovery intervals can range from a few seconds to a few minutes, while the work interval intensity varies based on your current fitness levels.

This comprehensive guide gives you an introduction to HIIT that includes the benefits, types of HIIT, sample workouts, tips for creating your own routine, and how to get started the right way.

Related HIIT Resources

If you're interested in tailoring a HIIT workout to your lifestyle and needs, check out these related GymBird resources:

An Introduction to HIIT

High-intensity interval training involves differing the intensity levels during a workout, typically a cardiovascular activity or strength training routine.

For example, while running on a treadmill, you will work at a high-intensity effort of 80 to 90 percent maximum heart rate for 30 seconds, followed by a 30-second recovery period performed at 40 to 50 percent of your maximum heart rate. This work-to-recovery period is continued for 20 or more minutes.

In general, the short bursts of vigorous activity should correspond to ≥80 percent of your estimated maximal heart rate, with more advanced fitness levels going as high as 95 percent maximum heart rate.

To help you determine your estimated maximal heart rate, consider using this chart from the American Heart Association (AHA). It shows estimated maximum heart rates based on age.

HIIT workouts should reflect your fitness level and take into consideration any health or medical conditions.

Therefore, it’s recommended to establish a firm aerobic base and be able to maintain the prescribed exercise intensity for a period roughly equal to the total time that will be spent on interval training.

With that being said, how you do HIIT is entirely up to you. For example, you may choose to do a HIIT workout outdoors with running as the activity or indoors on a treadmill.

HIIT workouts also involve strength training routines with specified exercises like squats, planks, burpees, mountain climbers, and push-ups. Additionally, many gyms and fitness facilities offer HIIT group classes, which is great news for beginners.

One thing that makes HIIT such a great training program to incorporate into your fitness routine is that you can select almost any aerobic exercise for an interval training workout.

This includes both indoor and outdoor activities. And if you can adjust the intensity easily and quickly, you can also perform HIIT on cardio machines. Plus, if you have access to different equipment and you’re doing a HIIT ratio with a more extended rest period, you can vary the workout by performing the work period on a stair climber and the rest period on a treadmill.

That said, if you’re doing a 1:1 work-to-rest ratio, change between machines may not be feasible.

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Benefits of HIIT

Making HIIT a part of your regular fitness routine has many benefits, including efficiency, improved health, and a higher calorie burn.

One of the biggest perks is accomplishing more exercise at higher intensities that are not typically possible with moderate-intensity, steady-state cardio programs. In other words, you get more done in less time.

And because HIIT uses the appropriate work-to-recovery ratio, you can train the body both aerobically and anaerobically.

HIIT also makes it easy to adjust the work interval intensity to match your needs, allowing you to start slow and increase the intensity as you get more comfortable and your fitness level improves.

Moreover, the combination of work to active rest periods maximizes your calorie burn and increases cardiorespiratory fitness in about half the time as steady-state cardio workouts.

And since HIIT uses anaerobic intervals, the American Council on Exercise (ACE) says your metabolism stays elevated due to excess post-exercise oxygen consumption or EPOC, which helps to burn calories hours after your workout is completed.

And while the health benefits are reason enough to consider this training style, HIIT is also convenient and easy to fit into most busy schedules.

That’s because you can perform the workouts anywhere, including the gym and at home.

Plus, since you’re not required to use any specific equipment, you can sneak in a sweat-dripping session any time of the day.

Types of HIIT

HIIT is a versatile exercise method many people can incorporate into a weekly routine. It’s also the foundation of several training methods that use HIIT as the base.

While not an exhaustive list, the following types of HIIT are the styles you may encounter most frequently when looking to try this workout type.


Tabata follows a specific protocol that is shorter in duration and more intense than most HIIT workouts. It consists of a four-minute block featuring 20 seconds of maximum intensity work, followed by 10 seconds of rest, repeated for eight rounds.

The key to making Tabata a success is pushing as hard as possible during the 20-second work period. Each four-minute bout focuses on one exercise, such as bodyweight squats, burpees, mountain climbers, or push-ups. You can also alternate two exercises within a four-minute period.

Traditional Tabata Four-Minute Workout


  1. Pick one exercise and perform it at maximum effort for 20 seconds. Sample exercises include bodyweight squats, push-ups, mountain climbers, squat jumps, burpees, and kettlebell swings.
  2. Rest for 10 seconds.
  3. Repeat eight times.

Advanced Tabata Workout


  1. Perform each exercise at maximum effort for 20 seconds. Four exercises in total.
  2. Rest 10 seconds.
  3. Repeat eight times.
  4. Rest for one minute, then continue to the next exercise.


  • High knees
  • Skaters
  • Mountain climbers
  • Squat jumps

Every Minute on the Minute

EMOM (every minute on the minute) is a type of HIIT that specifies an exercise and the number of repetitions to perform at the start of each minute.

Once you complete the number of repetitions, you can rest until the minute is up. Yes, you will get more rest if you race through the reps, but remember form matters.

EMOM is a common protocol used with kettlebell training. For example, 12 reps for 12 sets of kettlebell swings.

Every Minute on the Minute Workout


  1. Set a timer for one minute.
  2. Start the timer and perform the exercise for the prescribed number of repetitions.
  3. Once you complete the number of reps, rest until the timer reaches one minute.
  4. Reset the timer and perform the next move.
  5. Do this sequence until you finish all of the exercises in the round.
  6. Rest for three to five minutes.
  7. Repeat the circuit two to three times.

EMOM Circuit:

  • Bodyweight Squats (20 reps)
  • Kettlebell Swings/or Jump Squats if you do not have access to a kettlebell (15 reps)
  • Curtsy Lunge (24 reps alternating sides)
  • Push-Ups (12 reps)
  • Burpees (10 reps)
  • Plank with Shoulder Taps (20 reps alternating sides)
  • Dumbbell Squat Push Press (15 reps)

As Many Rounds (or reps) as Possible

With AMRAP (as many rounds or reps as possible), you build a routine around reps or rounds. If the “R” is rounds, you will perform a certain number of exercises for a specified number of reps for a set amount of time.

The goal is to complete as many rounds as possible in the allotted time. But if the “R” stands for reps, the goal is to complete as many reps as possible for a specific exercise, like burpees, in a set amount of time.

15-Minutes As Many Rounds as Possible Workout

  1. Set a timer for 15 minutes.
  2. Perform each exercise for the prescribed number of repetitions.
  3. Repeat the sequence and complete as many rounds as possible in the time frame.


  • Walking Lunges (20 reps)
  • Plank Jacks (15 reps)
  • Skaters (20 reps alternating sides)
  • Bicycle Crunches (20 reps alternating sides)

Work-Recovery Ratio HIIT

The ACSM recommends a work-to-recovery ratio when doing HIIT. This ratio is often a 1:1 interval training program. For example, a three-minute high intensity work period followed by a three-minute recovery or low-intensity period.

A 1:1 ratio allows for an equal work and recovery time. As you progress, consider changing the ratio to make the workout more challenging. For example, a high intensity work interval of 30 seconds followed by a 15-second active recovery rest period.

Cardio Machine HIIT with 1:1 Ratio Workout

  1. Choose a cardio machine such as a treadmill, exercise bike, elliptical, or stair climber.
  2. Set the timer for the desired workout time (for example, 20 to 30 minutes) and your 1:1 ratio time (for example, 30 seconds, 1 minute, or 2 minutes)
  3. Begin with a three-minute warm-up at low to moderate intensity.
  4. Increase the speed or resistance to move at a high intensity.
  5. Do this work ratio for two minutes or your prescribed time.
  6. Reduce the resistance or speed and complete the two-minute recovery or low intensity period.
  7. Repeat this sequence for the remainder of the workout.

Creating Your Own HIIT

What makes HIIT such an excellent exercise method is you can customize the workouts to fit your fitness level, schedule, and goals.

Plus, there are a lot of workouts already available online, through fitness apps, and at the gym, so learning how to create a HIIT routine is actually quick and easy.

That said, implementing HIIT requires patience and time. Going from low or moderate-intensity workouts to vigorous exercise requires pacing and practice.

So while you might be ready to jump in with both feet, your best bet is to add vigorous workouts gradually. With that in mind, here are some HIIT program components to help you get started on the right foot.

HIIT Program Components

Introduce HIIT the right way

For example, swap out one slow-state cardio session for a HIIT workout on week one. In week two, consider adding another vigorous workout, but make it a circuit-style strength training session.

And most importantly, allow yourself at least two to three days between HIIT sessions to rest and recover.

Frequency of sessions per week

The first step is determining the number of days you’ll perform HIIT each week. Building on the guidelines from the first component, starting with one or two sessions each week is recommended.

As your body adjusts and your fitness level increases, consider adding another session. Two to three HIIT sessions per week are enough to see and feel the benefits.


You’ll need to decide on the total workout time and the duration of each work-to-rest interval. HIIT sessions are generally shorter than other cardio and strength training workouts.

Total time can range from 10 to 30 minutes, with 20 minutes being the average. Once you determine the workout time, you’ll need to decide the length of each interval. One way to get started with this is to use the 1:1 ratio. For example, a cardio HIIT workout could feature 30 seconds of high-intensity running, followed by 30 seconds of walking repeated for the entire session.

You can also use one of the HIIT types detailed in this guide as a starting point.

Interval intensity

Typically, the work intervals approach 80 to 95 percent of your maximum heart rate, and the recovery intervals are generally 40 to 50 percent of the maximum heart rate, according to the ACSM.

Recovery between intervals

The amount of time you recover between near-maximal bouts of activity depends on your current fitness level and the type of HIIT you’re performing. Beginners might need a higher active recovery than someone who is an experienced athlete.

The goal is to let your body rest just enough to prepare for the next bout of high-intensity work. However, you don’t want to rest too much, or else the benefits of HIIT will diminish.

Type of recovery

The recovery type will be dependent on the activity. If you’re using cardio machines, the recovery or active rest period might be a less intense version of what you’re doing. For instance, walking instead of running or reducing the resistance level of a stair climber.

If you’re performing a bodyweight HIIT routine, the recovery between exercises could be walking in place. Some people may need complete recovery during this interval and prefer to stop the activity altogether.

How to Get Started with HIIT

Before jumping into a HIIT workout, there are some basic guidelines that apply to all fitness levels. Here are some tips to help you get started and stay motivated during your workout.

Make Sure HIIT is Right for You

Turning up the intensity in your exercise sessions saves time while still getting an effective workout. However, while vigorous exercise is a key component in an overall workout program, it’s not appropriate for everyone.

If you have a health condition requiring exercise modifications, make sure to talk with your doctor before working out at this level.

Decide on Equipment

One of the best things about HIIT is that you can do it anywhere and without equipment. For example, performing a bodyweight HIIT workout at home only requires your body weight and a large enough space for moves like push-ups, squats, and mountain climbers.

That said, HIIT also works great with cardio machines like a treadmill or exercise bike and resistance equipment such as kettlebells, dumbbells, and bands.

Ease Into HIIT Workouts

Easing into a HIIT routine is the best way to avoid injury and burnout. Training at this level is intense, so the number of workouts each week should be at most two. You can consider adding one more day of HIIT as your fitness level increases.

It’s also a good idea to stagger HIIT workouts. For example, perform a HIIT workout on Monday and Thursday, and use the other days for moderate-intensity cardio, strength training, cross-training, rest, or other modalities like yoga.

Slow and Steady to Start

Allowing enough time to warm up will make a difference in the quality of your workout. Ideally, the warm-up should last about five to 10 minutes before you build into the intensity of the intervals.

Warm-Up and Cool Down the Right Way

The warm-up can be light cardio, such as jogging in place, high knees, or walking, followed by a few dynamic stretches like hip circles, arm circles, and leg swings.

Dynamic stretches allow you to move your joints and muscles through a full range of motion. When you’re done with a HIIT workout, spend a few minutes cooling down and performing a few static stretches such as a seated hamstring stretch, standing calf stretch, and kneeling hip flexor stretch.

These moves require you to hold a stretching position for 30 to 60 seconds.

Sleep, Eat, and Hydrate

Performing HIIT workouts requires a lot of energy. For best results, make sure to get plenty of sleep each night and allow for a minimum of two rest days between HIIT sessions.

How you fuel your body matters too. Make it a point to hydrate before, during, and after each workout and eat a healthy diet.

A Word from Ashley

HIIT workouts are one of my go-to fitness routines. I love HIIT workouts because they don't take up much time, so I can sneak them into my busy schedule. HIIT workouts also quickly jack up my heart rate, so I know I'm improving my cardiovascular fitness, which is one of the reasons I work out. And when I'm doing a well-rounded HIIT workout, I use lots of different muscle groups, so it's a total-body workout.

While I love HIIT, I definitely had to ease into making HIIT part of my fitness routine. HIIT can be hard on my joints, so if I'm feeling any joint pain, I'll skip my HIIT workout and do something that's low-impact instead. I quickly learned that for me personally, I couldn't do a HIIT workout every single day.

If you ease into a HIIT workout, go at your own pace, listen to your body, and do modified movements if necessary, you should be good to go, as long as you've gotten the okay from a physician or personal trainer.


High-intensity interval training, or HIIT, is an effective and efficient way to increase strength and cardiorespiratory fitness in a short amount of time. It’s also a great way to burn calories.

However, HIIT workouts are performed at near maximal effort with short recovery periods, so you should only do them a few times each week with at least two days between sessions.

It’s also advisable to consult with your physician or healthcare provider if you have any medical or health conditions before starting a HIIT program.