High-Intensity Interval Training (HIIT) is a type of exercise that requires you to push yourself close to maximum effort for short periods with longer breaks to recover.
HIIT differs from circuit training, which involves longer stretches of moderate-intensity exercise with shorter breaks, and steady-state cardio, which involves exercising at the same intensity (low or medium) for even lengthier periods without breaks.
What Is Cardio?
Cardiovascular exercise or cardio—also known as aerobic exercise—describes rhythmic activities that raise the heart rate.
Cardio differs from other types of exercise, including strength training, because it relies on the body’s ability to use oxygen throughout the session.
Cardio is also known as aerobic exercise because “aerobic” refers to something involving or requiring oxygen.
During aerobic workouts, the body relies on oxygen to break down stored energy and produce adenosine triphosphate (ATP).
ATP is responsible for energy storage and transfer within the cells. It plays a critical role in several bodily processes, including muscle contraction.
Traditional cardio workouts rely primarily on the body’s slow-twitch muscle fibers. According to the American Council on Exercise (ACE), these muscles provide their own energy source, meaning they can work for extended periods before becoming fatigued.
Types of Cardio Workouts
Well-known examples of cardio include walking, jogging, swimming, and cycling. Household chores like vacuuming or mopping can also elevate the heart rate and count as aerobic workouts, though.
Cardio performed for extended periods is often described as steady-state cardio — because you’re maintaining a steady pace throughout the workout. Steady-state cardio can also be divided into low-intensity steady state (LISS) and medium-intensity steady state (MISS).
What Is HIIT?
HIIT requires you to work harder than traditional cardiovascular workouts. An example of a HIIT workout might be sprinting for 15 seconds on a treadmill and then resting for 60 seconds.
Because you push yourself so hard during HIIT training, you need more time to recover before moving on to the next round. When you’re working at close to maximum effort, you can’t go for very long before you have to take a break.
Aerobic vs. Anaerobic
While regular cardio workouts are considered aerobic exercise, HIIT cardio is considered anaerobic.
During a HIIT workout, the work intervals don’t exclusively rely on oxygen. Instead, they’re primarily fueled by glycogen (stored glucose molecules). The process of breaking down stored glucose is known as glycolysis.
While cardio workouts rely more on slow-twitch fibers, HIIT workouts rely on fast-twitch muscle fibers. Fast-twitch fibers are bigger, take less time to reach peak force, and generate more power than slow-twitch fibers. They also fatigue more quickly.
Types of HIIT Workouts
According to the National Academy of Sports Medicine, HIIT comes in numerous forms, including the following:
- Tabata: Tabata workouts involve 20 seconds of work followed by 10 seconds of rest. This sequence is repeated eight times, meaning you can complete the workout in just four minutes.
- 30:30: During these workouts, you perform 30 seconds of high-intensity exercise followed by 30 seconds of lower-intensity exercise to recover. For example, you might do 30 seconds of sprinting followed by 30 seconds of walking.
- 30-20-10: During these workouts, work intervals are split into 60-second increments. The first 30 seconds involve low-intensity exercise, followed by 20 seconds of moderate-intensity exercise, followed by 10 seconds of high-intensity exercise.
Whatever style of HIIT workout you do, remember that the primary goal is to push yourself as hard as possible (without compromising form or risking your safety, of course) during each work period.
Get our fitness newsletter
Stay on track with your fitness goals and get inspired! Sign up for the GymBird newsletter for twice-monthly expert fitness and nutrition tips.
Cardio vs. HIIT
Do you want to know more about what makes HIIT unique? The answers to these frequently asked questions can give you more insight.
What Do HIIT and Cardio Workouts Have in Common?
Traditional cardio workouts and HIIT have a few key similarities, including the following:
Because cardio and HIIT elevate the heart and breathing rate, they both help you burn calories (although their calorie-burning potential is not the same).
Over time, if you do either steady-state cardio or HIIT workouts consistently, you’ll notice that your stamina improves. Both traditional cardio and HIIT can increase cardiovascular endurance and muscular endurance.
Heart Health Benefits
In an interview with Penn Medicine, exercise physiologist Chris Kusmiesz explained that there are similar heart health benefits from HIIT and steady-state cardio. Improved heart health can reduce one’s risk of developing several chronic health conditions, including coronary artery disease, hypertension, and diabetes.
Mental Health Benefits
Another similarity between cardio and HIIT is that they both offer mental health and mood-balancing benefits.
Any type of exercise, from jogging to doing HIIT with a jump rope, promotes endorphin production. Endorphins are feel-good chemicals that boost mood and reduce pain.
What Are the Differences Between Cardio vs HIIT?
Although these two workouts share some similarities, cardio and HIIT have many more differences.
HIIT Burns More Calories
Both cardio and HIIT workouts burn calories. However, for those who want the best option for weight loss, HIIT will typically yield better results in a shorter time frame.
After performing HIIT workouts, the body burns more calories as it works to return to a state of equilibrium. This phenomenon is known as afterburn or post-exercise oxygen consumption (EPOC).
HIIT Improves Insulin Sensitivity
Remember, during HIIT workouts, the body primarily uses stored carbohydrates for energy.
Regular HIIT workouts can help the muscles use glucose more efficiently than steady-state cardio workouts, making them a better option for those who need help managing metabolic conditions like type 2 diabetes.
When you use glucose efficiently, your body’s insulin sensitivity increases (insulin is a hormone that moves glucose from the bloodstream to the muscle cells, where it can be used for energy). Increased insulin sensitivity, in turn, reduces your risk of developing diabetes.
HIIT Takes Less Time
One of the greatest draws of HIIT workouts is that they take less time.
You might not have 45-plus minutes to spend on a treadmill or a stationary bike. However, you likely can find 15-20 minutes to squeeze in a HIIT workout at some point in your day.
Keep in mind, too, that a little goes a long way with HIIT workouts.
One study published by the Journal of Sports Sciences showed that just three 10-minute HIIT workouts per week made the body more efficient at delivering oxygen to the muscles. It also produced significant benefits to test subjects’ metabolic health.
HIIT Busts Boredom
Some people struggle to consistently incorporate cardio into their workout routine because they find it boring. They don’t like slogging away on the treadmill or stationary bike for 30-60 minutes and would prefer something more dynamic and engaging.
That’s where HIIT comes in. It’s harder to get bored during a HIIT workout when you’re pushing yourself to your limit and trying to recover before the next work interval starts.
What’s the Difference Between Cardio, HIIT, and Circuit Training?
While cardio is aerobic and HIIT is anaerobic, circuit training can fall into either category. It depends on the workout’s intensity and duration.
Many people like circuit training because it allows them to enjoy the benefits of cardio and strength training. Circuit workouts also take less time than traditional cardio workouts (although it’s typically not as efficient as a HIIT session).
Can You Build Muscle with Cardio?
A frequently spread myth in the fitness world is that cardio will ruin your gains and prevent you from building muscle. That’s not necessarily true, though.
Cardio Contributes to Growth
Some research suggests that cardio can contribute to muscle growth.
A review of 14 studies revealed that aerobic exercises like running, walking, and cycling increased leg muscle mass. One of the study’s authors even noted that aerobic exercise could result in as much muscle growth as resistance exercise.
As long as you’re consuming enough calories to support your muscle-building efforts — remember, you have to eat in a calorie surplus (eat more than you burn) to gain muscle — you don’t have to choose between cardio and strength training.
Don’t Sleep on Strength Training
Cardio does not stop you from building muscle by any means. However, it’s also not the most ideal form of exercise for muscle gain.
Generally speaking, the best way to build muscle is through strength training (lifting weights, performing bodyweight exercises like squats, etc.). You can still do steady-state or HIIT cardio to experience other benefits, though (such as improved heart health).
Choose HIIT for Maximum Muscle Preservation
If you want to incorporate more cardio into your routine but don’t want to worry about sacrificing muscle, choose HIIT workouts.
Some research, including this study published by the International Journal of Sports Medicine, shows that HIIT does a better job of preserving muscle mass compared to steady-state cardio.
Do You Need Equipment for Cardio or HIIT?
Both cardio and HIIT workouts can be done with or without equipment.
For an equipment-free option, you could jog around a track for 30 minutes for an aerobic workout. You could also do HIIT training by alternating between sprinting and slow walking.
You can also use equipment like a stationary bike for cardio and HIIT workouts. Work at a low or medium intensity on the stationary bike for cardio training, or do sprint intervals followed by longer rests for an efficient and effective HIIT workout.
Can HIIT Use Cardio-Type Exercises?
Many HIIT workouts involve cardio-type exercises, such as sprinting and cycling. You could also use cardio equipment like a Stairmaster or rowing machine.
Along with cardio-type exercises, you can also incorporate other types of exercise into HIIT workouts. For example, you could do jump rope intervals or kettlebell swing intervals.
Is HIIT Safe for Beginners?
It’s always a good idea to consult with your doctor before starting a new fitness routine, especially if you’re not sure if it’s a safe workout for you.
Beginners can do HIIT workouts safely and may find them easier to stick to since they’re shorter.
Remember that it’s best to work with a certified personal trainer or another fitness professional if you’ve never done this type of training before. A trainer can ensure you’re performing exercises with proper form and avoiding injury.
That being said, some beginners may want to work their way up to high-intensity workouts like HIIT.
If you’re brand new to working out, HIIT might be intimidating. You may feel more confident sticking with LISS or MISS while you find your footing (literally or figuratively) in the gym.
What Are Some Common HIIT Workout Mistakes?
The following are some of the most common mistakes people make during HIIT workouts:
- Not pushing themselves hard enough: You should need a break when the work interval ends because you’ve pushed yourself so hard
- Not warming up: Always warm up before HIIT workouts to avoid injury
- Picking complex movements: Doing complicated exercises can make it harder to push yourself because you’re too focused on doing the exercise correctly
If you’re concerned that you’re not getting the most out of your HIIT workouts, don’t hesitate to contact a trainer or another fitness professional.
Cardio vs. HIIT Workout Breakdown
Do you need a simple breakdown of the differences between cardio and HIIT? Check out the table below:
|Workout Type||Definition||Best For|
|Cardio||Rhythmic activities that raise the heart rate.||Exercisers of all levels, including beginnersThose interested in building endurance|
|HIIT||Brief intervals of intense work followed by more extended rest periods.||Intermediate-advanced exercisesThose who want to burn more calories during their workoutsThose interested in preserving muscle mass|
HIIT, steady state cardio, and circuit training are all great exercise options for those who want to elevate their heart rate, build stamina, and diversify their workouts.
If you’re looking for the most efficient option, HIIT wins. However, if you aren’t ready for the intensity of HIIT workouts just yet, you can still see great results from circuit training or steady-state cardio.
At the end of the day, the most important thing is that you’re exercising regularly — whether that means HIIT, steady-state cardio, or a combination of the two.
Remember the information discussed above so you can make the right choice for your unique needs, interests, and fitness goals.
More Cardio Advice from GymBird Experts
- What is Cardio?
- Cardio for Beginners
- Best Cardio Workouts
- 5 Cardio Workouts at Home
- Cardio Workouts for Runners
- Cardio with Weights
- Cardio vs. Walking
- How to Avoid Cardio Injuries
- Is Cardio Aerobic or Anaerobic?
- Top Cardio Benefits