If you’ve been working out for a while – or even just reading about it – you’ve probably come across the term HIIT. It’s been trending for years, but with its low prep and minimal equipment, it exploded in popularity during the pandemic. Almost every gym or fitness app offers it on their schedules: HIIT Class or HIIT Boot Camp are two of the most in-demand workouts right now.
But what exactly is HIIT? What are its benefits? And most importantly: should you choose HIIT or cardio workouts to reach your fitness goals?
What Is HIIT?
This is not your regular cardio workout! It’s the pumped-up, super-sized version of cardio.
HIIT stands for High Intensity Interval Training. And its name says it all:
- Intensity: The intensity of your workout is dialed up to its maximum, pushing you out of your comfort zone. You’ll be pushing your body to perform at its peak level.
- Intervals: The intensity of a HIIT workout is so elevated that it can’t be sustained, thus the second part of its name: the intervals.
Put simply, a HIIT workout is made up of short, intense bursts of exercise with rest or active recovery periods in between.
HIIT: Intensity
There’s no getting around it: these workouts are incredibly heart-pounding! For scientific and/or research purposes, a workout is only considered a HIIT workout if your heart rate reaches at least 80% of its maximum capacity.
How to Calculate Your Maximum Heart Rate
Your heart rate is the most objective way to be sure that your HIIT workout is challenging enough. To calculate your maximum heart rate, subtract your age from 220. If you’re 40 years old, that gives you the number 180. This means that your heart rate during a HIIT workout should be an incredible 180 beats per minute!
But even if you have the same maximum heart rate as your “gym buddy,” everyone reaches their 80% at a different performance level. What you need to do to achieve 80% of your heart rate might not be exactly what they need to do. If you do your HIIT workouts with someone else, make sure you are each pushing yourselves to your max.
Another way to calculate your intensity level is using the Rate of Perceived Exertion (RPE) Scale. On a scale of 1-10, anything over a 7 would be considered a HIIT workout. At this level, you would consider your workout to be hard/heavy and have difficulty carrying on a conversation – you’d be too breathless to talk.
HIIT: Intervals
Usually, a HIIT workout is performed for a predetermined amount of time and for a set number of rounds. You’ll alternate between exercise periods and rest or recovery periods. During the exercise periods, your heart rate should be at 80%-95% of your max heart rate. During the rest/recovery, it should go back down to 40%-60%.
One of the most common HIIT timings is a 20:10 combination. You workout out intensely for 20 seconds followed by 10 seconds of rest. You do this for 8 rounds, for a total of 4 minutes. You’ll then have 1 minute to recover before moving on to the next round. Because the “work” intervals are so short, this workout to be highly effective, you need to push yourself beyond the 80% heart rate.
Another popular HIIT timing is a 1:1, with one minute of work followed by one minute of rest. If you’ve been working out for a while now, you can probably push that to 2:2 or even 3:3. Since this calls for a slightly longer period of sustained exercise, you’ll probably be closer to the 80% mark.
Because of their high intensity, HIIT workouts won’t be your typical hour-long workout. Most of these workouts run under thirty minutes, and definitely no longer than 40 minutes. Because if you can sustain the intensity for that long, you’re probably not pushing your muscles as hard as you should be for a true HIIT workout.
What’s the Difference Between HIIT and Cardio?
If you read a list of HIIT exercises, they might seem like traditional cardio exercises: jumping rope, rowing, and running could all be part of a high-intensity workout. So how do you distinguish HIIT vs. cardio?
Think of a marathon versus a sprint.
- Marathon = Cardio: running slower for a longer period of time
- Sprint = HIIT: running as fast as you can for a shorter period of time.
The main difference is the exertion (how much energy you are using). Traditional cardio, also known as steady state cardio, uses a lower rate of exertion, so it can be done for a longer period of time. HIIT is done at such a high intensity level that it can’t be sustained for very long.
Benefits of HIIT
Recently it seems that every fitness magazine you pick up is extolling the benefits of HIIT workouts.
The most commonly cited benefits are:
- Lose weight
- Build muscle
- Boost metabolism
But those results are purely physical and visible to the human eye. The research shows that HIIT has many more benefits, many of which aren’t as readily apparent.
Burn More Calories
Studies show that HIIT can burn 25%-30% more calories than other cardio workouts. This data is based on a 20:40 HIIT workout, meaning that not only did the higher intensity workout burn more calories, it did so even though the participants were only actively working out for 1/3 of the time.
Raise Your Metabolic Rate for Hours Afterwards
Study after study has shown that HIIT exercises can raise your metabolic rate for hours after you’ve finished working out. Some even indicate that your metabolic rate will remain elevated for up to 24 hours. Why does this matter? The higher your metabolism, the more calories you are burning, even when you are sedentary.
Lose Fat
Like most forms of cardio, HIIT workouts can help you lose fat and waist circumference. The advantage that HIIT has over other forms of cardio is that you can lose fat faster, since your workouts are shorter. Plus, it gives you that added metabolism boost, which will have you burning off calories – and losing fat – for hours after your workout.
Gain Muscle
For newer gym-goers, HIIT can help you gain some muscle mass, although not as much as strength training. But if you are just beginning your fitness journey, you will notice some difference in your muscles. Depending on the type of exercises, this will probably be most noticeable in your legs, glutes or core.
There are some options for HIIT that include lifting heavy weights for your exercise. In this case, you will notice the muscle gains with time and consistency.
Improve Oxygen Consumption
Any kind of steady state cardio (long runs or bike rides, for example) will improve your body’s ability to consume oxygen. The difference with HIIT is that you will have the same effect but with shorter workouts – even as little as half the time.
Improve Overall Health.
For overweight or obese participants, HIIT can reduce their heart rate and lower their blood pressure.
HIIT workouts can also be beneficial if you are at risk for type 2 diabetes. Studies have shown that it reduces blood sugar and can improve insulin resistance more than other types of exercise, including steady state cardio.
Quick, Convenient Workouts
Don’t have time for a long run? HIIT only takes 20-30 minutes to be effective. On those days when you are having trouble finding the time to work out, a HIIT workout is easier to squeeze in. It’s also just as effective – or more!
Plus, you can do a HIIT workout – in your house, yard, on the beach, in a hotel room. Wherever you find yourself, as long as you have room to move, you can exercise.
No Equipment Necessary
One of the biggest benefits of HIIT workouts is the lack of equipment needed. Sure, it’s nice to schedule your workout at the gym, where you have access to cardio equipment, medicine balls, and anything else you might want to incorporate. But you can do your HIIT just as easily without any equipment, using your body weight alone.
Drawbacks of HIIT
If you have been exercising for a while and are ready to take your workouts to the next level, there aren’t too many drawbacks to HIIT.
Body Soreness
Because you really are going all-out during a HIIT workout, you can expect to have some sore muscles, especially at first. If you are new to HIIT, or to working out in general, start slow. If you overdo it in the beginning, you could find yourself with sore muscles and joints or even an injury.
Not Going Hard Enough
On the flip side, if you really want to reap the benefits of a HIIT workout, you have to make sure that you are working out hard enough. Since this is a different level for everybody, it is up to you to make sure that you are getting your heart rate high enough.
Can’t Be Done Every Day
HIIT workouts are simply too taxing on the body to be done every day. In fact, most researchers would recommend no more than two of these workouts per week. And since most people want to work out more often than that, you will need to add some other workouts to your schedule.
Doesn’t Build Enough Muscle
If you truly want to build muscle mass, HIIT won’t do it – not even strength training HIIT. It will give you a leaner, more toned body, but not bulk you up. If increased muscle mass is your goal, this type of workout alone isn’t for you.
How Effective Are HIIT Classes at the Gym?
In a survey of fitness professionals by the American College of Sports Medicine, HIIT was ranked as one of the top five fitness trends. So it’s no wonder that it’s one of the most-requested class formats at the gym. HIIT, HIIT Boot Camp, HIIT Boxing, and HIIT Spin are all some of the most popular classes on the schedule.
Unfortunately, not all HIIT classes (online or in gyms) really stay true to what is considered a HIIT. Instead, they tend to be interval training, but not necessarily at the required intensity level.
For one thing, most classes are designed to be more inclusive and appeal to the average gym-goers. This means they can’t be overwhelmingly difficult. Plus, gym classes tend to be an hour long. A true HIIT workout can’t be sustained for that period of time. Most classes are made slightly easier, so participants can stay for the full hour.
Also, in a class setting, more time is spent explaining exercises and proper form, which can result in too much time being lost between exercise bursts. In a true HIIT class, all of the exercises will be explained before the beginning of class. Participants can then move from one to the next without long pauses.
You might love your Wednesday night HIIT Boot Camp, but keep in mind that it might not actually be a HIIT class.
How to Make Traditional Cardio a HIIT Workout
HIIT workouts can be composed of almost any form of cardio: running, cycling, rowing, and stair climbing can all be part of a HIIT workout. The key difference is the intensity level at which you are performing the exercise. For a high intensity workout to be effective, your body has to go all-out for the entire time you are working. You can’t coast through a HIIT workout.
Traditional cardio tends to find its rhythm and remains there without changing. This is called a steady state workout. These workouts tend to be medium intensity, lower than HIIT would be, so you can do them for longer than you would a higher-intensity workout.
Take running, for example. Running 5 miles in 40 minutes would be a classic (and effective) cardio workout. But when you run for 30 seconds at an all-out leg-burning pace, before slowing to a jog for the next 30 seconds, that’s when your workout crosses over the threshold and becomes a HIIT workout.
So to turn a traditional cardio workout into a HIIT workout, all you have to do is add in intense intervals. If you’re a runner, you’ve probably been doing this without even knowing it, since most avid runners train using sprint intervals at least once per week. Whatever your favorite cardio workout happens to be, you can incorporate it into your HIIT workout with those intense bursts.
Examples of Cardio HIIT Exercises
Some cardio exercises to lend themselves better to HIIT. These would include:
- Running
- Cycling
- Jumping rope
- Roller skating
- Swimming
- Box jumps or plyo jumps
- Jumping jacks
- And more
Add those intense intervals, and you can do your favorite exercises during your HIIT workout.
Can Strength Training Be Part of a HIIT Workout?
Absolutely! In fact, you’ll often find that HIIT classes at any local gym will include a combination of aerobic and strength exercises. Most instructors will shy away from traditional equipment, such as dumbbells. Instead, they will opt for less-used but just as effective strength training equipment such as:
- Kettlebells
- Medicine balls
- Slam balls
- Battle ropes.
Body weight exercises can also play a role in HIIT strength training exercises. These would include:
- Pushups
- Walking lunges
- Squats
- Pullups
Adding strength training exercises into a HIIT workout is an effective way of getting the best of both worlds. There are just a few things you should keep in mind to ensure that you are getting the best results from both types of exercises.
Increase Your Weights
One of the keys to unlocking the benefits of a high intensity workout is getting your heart rate higher. That won’t happen if you are using your usual weight combos. If you want to add strength training to HIIT, heavier weights will get your heart rate higher.
Decrease Rest Periods
It’s challenging enough to elevate your heart rate to 80% or higher while weight lifting. Decrease your rest periods so that your heart rate never gets the chance to dip too far down.
Focus on Compound Moves
A compound exercise is one that utilizes more than one muscle group at a time or works an entire large muscle group. These types of exercises are more challenging and therefore more effective at raising your heart rate during your HIIT workout.
Keep Cardio in the Mix
Even if your workout is focused on strength training moves, add in some cardio to elevate your heart rate and get the HIIT benefits. For example, instead of doing squats, do squat jumps. You’ll get the benefits of strength training (squats) and HIIT (jumping). Or, alternate moves from between the two. Follow a strength exercise such as lunges with a classic HIIT move such as jumping jacks.
Should I Choose HIIT or Cardio to Meet My Goals?
It depends on what your goals are.
Burn Calories in a Short Amount of Time: HIIT will be more effective at this than cardio, burning 25-30% more calories.
Build Endurance: HIIT is not sustainable for a long amount of time, so it won’t build endurance. Steady state cardio will help you meet this goal.
Boost Metabolism: Both forms of exercise will help you boost your metabolism, but HIIT will raise it higher and keep it raised for longer.
See Fast Results: HIIT will give you faster results.
Build Muscle: Traditional cardio helps you lose fat – and muscles. On the other hand, with HIIT you not only don’t lose muscle, you can gain lean muscle.
Feel Better Mentally/Emotionally: Both will release feel-good endorphins into your body. However, endorphin levels aside, since steady state cardio is more rhythmic in nature and also less taxing on your body, it will leave you feeling more peaceful and relaxed than an exhausting HIIT workout.
Workout with Friends: If your workout is your social hour, cardio is probably your best choice. On the RPE scale, cardio can be done at a pace that allows you to talk comfortably. HIIT, on the other hand, will leave you breathless. So while you can perform HIIT exercises side by side with your gym buddy, forget about catching up while you work out.
Can Beginners Do HIIT?
Yes! Anyone can do HIIT, as long as you are careful and don’t overdo it.
Here are some tips to help you start out with HIIT workouts:
- Try to keep your heart rate right at 80% of your max, without going higher.
- Stay within some of the shorter time periods, such as a 20:10 or a 30:30. Don’t stay in the exercise round for too long.
- Keep your workouts short, under 20 minutes initially.
- Allow for plenty of recovery time in between workouts. You will be sore for at least a day or two after your first few workouts, so don’t plan on doing anything strenuous.
- Start with just one HIIT workout per week at first. Add variety with other exercises before adding in a second HIIT workout.
- Build in time and intensity slowly.
Note: If you have not been working out frequently, check with your doctor before beginning any type of workout.
Sample HIIT Workouts
To get you started, here is a HIIT workout you can do today with little to no equipment. Make sure you warm up for at least 4-5 minutes and cool down and stretch afterwards.
HIIT Workout #1
This is a 20:10 HIIT workout. Each round consists of 8 exercise segments. You’ll be working out for 5 rounds, 20 minutes, with 1-2 minutes to rest between each round.
Round 1: Four times for a total of four minutes
- 20 seconds jumping jacks
- 10 seconds rest
- 20 seconds mountain climbers
- 10 seconds rest
Rest: 60 seconds
Round 2: Four times for a total of four minutes
- 20 seconds split leg jumps
- 10 seconds rest
- 20 seconds squat jumps
- 10 seconds rest
Rest: 60 seconds
Round 3: Four times for a total of four minutes
- 20 seconds lateral shuffles
- 10 seconds rest
- 20 seconds burpees
- 10 seconds rest
Rest: 90 seconds
Round 4: Four times for a total of four minutes
- 20 seconds jump rope
- 10 seconds rest
- 20 seconds pushups
- 10 seconds rest
Rest: 2 minutes
Round 5: Four times for a total of four minutes
- 20 seconds walking lunges
- 10 seconds rest
- 20 seconds plank to hip dip (alternate sides each set)
- 10 seconds rest
HIIT Workout #2
This is a 30:30 HIIT workout. You have 8 identical rounds, for a total of 12 minutes. Beginners can start off with less rounds. As you advance, you can add time, rounds, or both.
Bring your pace up: 2 minutes
- 1 minute slow jog
- 1 minute jog
Rounds 1-8
- 30 seconds sprint
- 30 seconds walk
Bring your pace down: 2 minutes
- I minute jog
- I minute slow jog
Although this is a running HIIT, you can also use the exercise periods on an elliptical, stair climber, or cycle.
What are your favorite HIIT exercises? Let us know in the comments!
