HIIT FAQ

“The quality of a leader cannot be judged by the answers he gives, but by the questions he asks.”

Simon Sinek

Frequently Asked Questions

Below you will find questions and answers to some of the most common issues surrounding High-Intensity Interval Training. I have provided a Table of Contents so that you can quickly maneuver to the question of your choice, but if you are a beginner, I suggest starting from the top and working your way down. If there is a question that you have which has not been answered here, please contact us and we will help you.

Contents

What is High-Intensity Interval Training?

High-Intensity Interval Training (HIIT) is a popular form of interval training that alternates between short bursts of High-Intensity with periods of Low-Intensity active rest periods. The high-intensity and low-intensity intervals can range anywhere from 10 seconds to 4 minutes long. Shorter high-intensity interval ranges (10-30 seconds) engage the anaerobic system for energy. Longer high-intensity interval ranges ranges (more than 30 seconds) will engage the aerobic system for energy. Generally, a HIIT workout (including warm-up and cool-down) can be completed within 30 minutes based upon the intensity of the workout. HIIT workouts have gained popularity due to their ability to provide similar health benefits to steady-state moderate intensity exercise in much less time.

What are the benefits of HIIT?

Research shows that HIIT is more efficient than steady-state moderate intensity exercise at improving aerobic and anaerobic fitness, cardiovascular health, resting blood pressure, fat burning both during and after exercise, muscle mass, and cholesterol levels. One study showed that three days of HIIT per week for two weeks doubled the aerobic capacity of participants from 25 minutes to 51 minutes in a time trial. Another study showed that HIIT provided 100% of the benefits of endurance training despite only 10% of the total exercise volume. HIIT takes less time than traditional endurance training and can provide more health benefits. Thus, HIIT is an efficient and effective workout for people who don’t have time to spend an hour at the gym.

Who can do HIIT?

HIIT has been studied on sedentary individuals, individuals with Type 2 Diabetes, heart failure patients and generally active adults. Multiple studies regarding the beneficial effects of interval training versus steady-state moderate-intensity exercise on at-risk populations have found significantly positive benefits for HIIT. Individuals who are just starting to workout or have serious heart or health conditions should get the approval of their physician before beginning strenuous activity like HIIT. Individuals who have already established a base level of aerobic fitness can add HIIT to their workout routine 2-3 times per week to replace traditional cardio.

Is HIIT safe?

Generally yes, but this will depend on your own fitness level and circumstances. If an aerobic endurance base is developed over time and the training protocols are followed properly, then HIIT can be a safe and effective method of exercise. Individuals who are just starting to workout or have serious heart conditions should get the approval of their physician before beginning strenuous activity. HIIT should not be the only form of exercise that you do during the week, but it can help you when you are crunched for time and need to workout quickly. Please review the Physical Activity Readiness Questionnaire and speak with your health care practitioner before beginning a new workout program.

What is the Physical Activity Readiness Questionnaire (PAR-Q)?

The PAR-Q is a questionnaire adopted from the American College of Scientific Medicine (ACSM) that may recommend for you to check with your physician before beginning any sort of physical activity. If you are not very active, it is always a great idea to check with your doctor first before beginning a new program. The main questions in the ACSM’s PAR-Q are provided below:

  1. Has your doctor ever said that you have a heart condition and that you should only perform physical activity recommended by a doctor?
  2. Do you feel pain in your chest when you perform physical activity?
  3. In the past month, have you had chest pain when you were not performing any physical activity?
  4. Do you lose your balance because of dizziness or do you ever lose consciousness?
  5. Do you have a bone or joint problem that could be made worse by a change in your physical activity?
  6. Is your doctor currently prescribing any medication for your blood pressure or for a heart condition?
  7. Do you know of any other reason why you should not engage in physical activity?

If you have answered “YES” to one or more of the above questions, consult your physician BEFOREengaging in physical activity. Please inform your physician which questions you answered “YES” to in this questionnaire. After a medical evaluation, seek advice from your physician on what type of activity is suitable for your current condition.

Why should I do HIIT?

Research shows that HIIT improves aerobic and anaerobic fitnesscardiovascular healthincreases fat oxidationmaintains muscle massimproves blood pressure, and improves cholesterol levels. And you don’t need to spend one hour on the treadmill or complete a complicated routine of 20 different bodyweight exercises in order to have an intense workout. You can read summaries of many of the major HIIT research studies in our database where you can review the results of the studies.

Will HIIT help me lose more weight than traditional endurance training?
Diet

Losing weight requires you to be in a caloric deficit. You can figure out how much to eat throughout the day by calculating your Total Daily Energy Expenditure (TDEE) and then eating at a deficit . Generally, to lose 1 pound a week, you will need to eat at a deficit of 500 calories per day.

Exercise

If you go on a 2-hour run, you will probably burn more calories doing ET than a 20-minute HIIT session. However, as your ET time decreases below the 1-hour mark, there is a stronger likelihood that HIIT will burn as many or more calories than ET throughout the day. HIIT may help you lose more weight than ET depending on the duration, intensity and frequency of your workouts, but it cannot be done everyday. Thus, a combination of HIIT and ET will be more effective at helping you lose weight than either form of exercise in isolation.

Do I need any additional equipment?

Equipment is not necessary, but here are the nice to haves for any beginner:

  • Interval Timer – you can download one for free from the App Store or the Google Play Store. The two most popular ones are called Interval Timer and Seconds. They both offer Free and Pro Versions of their app and allow you to customize the intervals.
  • Heart Rate Monitor – This can help you make sure that you are in a high-intensity zone based on your heart rate. Apple Watch, FitBit and other smart devices provide this information for you.
  • Stationary Bike – Most of the research articles for HIIT were done on a stationary bike (aka cycling ergometer) because of the accuracy of measuring power output and total work. Cycling is a very simple, efficient and fun way to workout at home.
Can I do HIIT more than once per day?

I would not recommend trying to do HIIT more than once per day for an average individual. The purpose of a HIIT workout is to give 100% effort during the workout and then allow proper time for recovery (ranging from 24-48 hours depending on your fitness level). A second HIIT workout would not be as efficient or effective as your first workout and can lead to injury if you are over-exhausting yourself. Instead of two HIIT workouts, you can add power walking or low-intensity cardio later in the day for active recovery. You don’t need to constantly give maximal effort to get the benefits of HIIT.

How many days a week should I do HIIT?

HIIT is generally recommended to be completed three times a week to reduce the possibility of overtraining and injury. Many researchers had their subjects perform HIIT on Mondays, Wednesdays and Fridays. Some researchers, like Tabata, took this further and included five workouts per week (4 HIIT workouts and 1 steady-state cardio workout). If you are a true beginner, you should start with moderate-intensity interval training every other day to test and build up your aerobic base before starting a HIIT program. You can adjust the intensity and frequency at a later point in time based on your fitness level, goals and schedule.

How high should I keep my heart rate?

The answer to this question depends on the age, fitness level, gender and other factors for each individual. After receiving clearance from your physician to engage in HIIT, you should increase the intensity of your exercise get your heart rate up to 80-95% of your heart rate maximum (HRmax) during your working intervals. You should then decrease the intensity to bring your heart rate back down to around 60-75% HRmax during your active rest intervals. One way to estimate your HRmax is to take 220 and subtract your age (i.e. a 25-year old has an HRmax of 195). The research articles regarding HIIT studied HRmax in the vigorous (80-95% of HRmax) and all-out (>95% of HRmax) ranges.

Here is a chart from the American College of Sports Medicine that will help you differentiate between your own high-intensity and low-intensity intervals. The chart also provides information relating to the Rate of Perceived Exertion (RPE) which is a subjective measure of how difficult the workout feels for you.

IntensityHRmaxRPE
Low (i.e. Walking)57-63%Very light to fairly light
Moderate (i.e. ET)64-76%Fairly light to somewhat hard
Vigorous (i.e. HIIT)77-95%Somewhat hard to very hard
All-Out (i.e. Sprinting)>95%Very hard
What are the five best exercises to do in a HIIT program?
Cycling
Running
Kettlebells 
Rowing
Stair Climbing
What are alternative exercises to do in a HIIT program?
Battle Ropes
Bear Crawls
Boxing
Box Jumps
Burpees
Elliptical
Jump Ropes
Squat Jumps
Swimming
Walking
What are the Research-Based HIIT Protocols?
The Tabata Protocol

Intervals: 8 sets of 20 seconds of high-intensity (all-out effort at 170% VO2max) / 10 seconds of low-intensity active recovery.

Research: The Tabata Training Protocol has gained a lot of popularity since the impressive results of the original study were published in 1996. The simplified version of the Tabata Protocol is only four minutes total. However, this doesn’t provide the full story. The participants in the Tabata Protocol performed HIIT four times per week with a 10-minute warm-up (easy effort at 70% VO2max) and included one day of 30 minutes of steady-state cardio per week. Tabata’s team found that HIIT on a stationary bike significantly improved aerobic and anaerobic capacity as compared to the moderate-intensity training group.

The Wingate Test

Intervals: 4-6 sets of 30 seconds of high-intensity (all-out effort) / 4 minutes of low-intensity.

Research: The Wingate Test is very popular among the academic community and has been studied extensively. The type of HIIT protocol in the Wingate study is known as Sprint Interval Training (SIT) because the working interval is an all-out effort that can only be maintained for 30 seconds and then 4.5 minutes of active recovery before the next set. Recently, the academic community has shifted to study more practical models of HIIT that don’t require all-out efforts above 100% VO2max and can be used by the general population. However, the research articles on the Wingate Test have provided the foundation of many of the benefits of high-intensity vs. low-intensity exercise.

The Little Protocol

Intervals: 10 sets of 1 minute high-intensity (~90% HRmax) / 1 minute low-intensity.

Research: The Little Protocol was developed by researching a more practical model of HIIT which could benefit glucose regulation and skeletal muscle metabolic capacity in patients with Type 2 Diabetes. The participants performed HIIT three times per week for two weeks. The study found that low-volume HIIT can rapidly improve glucose control and induce adaptations in skeletal muscle that are linked to improved metabolic health in patients with Type 2 Diabetes.

The Meyers Protocol

Intervals: 13 sets of 30 seconds of high-intensity (100% VO2max) / 60 seconds of low-intensity.

Research: The Meyers Protocol was developed by testing three different types of interval protocols on individuals who were previously deemed to be unsuitable for interval training (namely, patients with chronic heart failure). The researchers used an intensity level of 50% of power output on a steep ramp test using a stationary bike which would approximately be 100% power output on a normal ramp test. This is more sustainable than an all-out effort like the Tabata or Wingate protocols. The researchers found that interval training had significantly less cardiac stress on the participants and can be recommended to at-risk populations.

The One-Minute Workout

Intervals: 3 sets of 20 seconds of high-intensity (all-out effort) / 2 minutes of low-intensity.

Research: The One-Minute Workout was developed by Dr. Martin Gibala and his team from McMaster University. This workout was popularized in his book because it is only a total of 1 minute of high-intensity exercise (3 sets of 20 seconds). The participants in the study worked out three times per week for twelve weeks. The HIIT group warmed up for 2 minutes, performed 3 sets of HIIT, then cooled-down for three minutes for a total workout time of 10 minutes. The ET group performed 45 minutes of steady-state cardio. The researchers found that this 1-minute HIIT protocol provided health benefits equivalent to the 45-minute ET group.

When can I do HIIT?
Morning

I’m a morning person, so I love to do my workout first thing before work to reset my body. If you are a morning person, I recommend doing a HIIT workout before starting your day and adding this to your morning routine.

Afternoon 

You can do walking intervals around your office building to prevent drowsiness after a big lunch. Light exercise in the afternoon helps you stay focused during the rest of the day. Also, taking the stairs rather than the elevator is another way for you to do a mini-workout without a big time commitment. You can try an intense workout if you have more time and access to showers and fresh clothes.

Evening 

Adding in exercise in the evening will help you feel more relaxed after work and allow you to sleep better at night. Just do it a few hours before you sleep so that you give yourself enough time to wind down.

Where can I do HIIT?
Home

The great thing about working out at home is that it is convenient. Bodyweight exercises (burpees, push-ups, squats) are a popular form of at-home HIIT programs. Additionally, if you own a stationary bike, treadmill, rowing machine, elliptical, kettlebells or a swimming pool, you can do many of these workouts.

Gym

Having a gym membership gives you access to all types of aerobic and weightlifting equipment that you can use to perform a variety of HIIT exercises. The gym has a huge motivational component in that everyone there is also working out. The gym also only has one purpose which will keep you focused during your workout.

Outdoors

Doing any of these workouts outdoors will give you additional benefits like sunlight, fresh air, and adventure. I love running and doing kettlebell workouts outdoors. I sometimes move my stationary bike outside when I make time to do my workout under the sun. Many people who work in offices all day are Vitamin D deficient. You can get your recommended 15 minutes of sunlight a day by doing a workout outdoors.

What variables differentiate HIIT from ET?
Frequency

Frequency includes the amount of sets you include in a workout and the number of times you can complete the workout per week. ET can be performed more frequently than HIIT, but the body adapts to the moderate-intensity level to make you more efficient at that movement which causes you to burn less calories during a subsequent workout.

Intensity

Intensity depends on the amount of effort you expend in a workout which is usually expressed in a percentage of HRmax or VO2max. HIIT can be performed at a much higher intensity (i.e. 85-95% HRmax) in shorter durations which can burn as many or more more calories than moderate intensity ET (i.e. 75% HRmax) during those working intervals and afterwards due to a concept known as EPOC (discussed below).

Time

Time is the complete duration of the workout, the working intervals and the resting intervals. ET generally lasts for a longer total duration compared to HIIT in a single workout. The longer your workout, the more calories you will burn in that workout.

How can one HIIT session burn more calories than a one hour cardio session?

One major difference between HIIT and ET is Excess Post-Exercise Oxygen Consumption (EPOC), which is more commonly referred to as the After-Burn Effect. The After-Burn Effect causes your metabolism to burn more calories post-exercise. And, it is increased by the intensity rather than the duration of a workout.

HIIT’s EPOC: HIIT (at 90-95% HRmax) has a greater After-Burn Effect than ET. EPOC lasts for about 2-hours post-workout where the body is trying to restore itself to pre-workout levels. During your workout, the body could not supply enough oxygen through your aerobic system to get you through the high-intensity intervals. Your body relied on your anaerobic system instead to supply energy (through ATP). Thus, after your workout, your body can burn an additional 6-15% of overall workout energy expenditure throughout the day because it needs to recover by replenishing oxygen levels, muscle glycogen, and stabilizing your body temperature.

ET’s EPOC: ET (at 65-80% HRmax) has less of an After-Burn Effect than HIIT. During your endurance workout, your body relies on a constant supply of oxygen through the aerobic system for energy. Once you complete your workout, your body stabilizes much more quickly than after a HIIT session because the oxygen levels have stayed consistent.

Can I lift weights if I am doing HIIT? 

Yes, resistance training is more effective than HIIT at building strength and muscle. If your goal is to build muscle, then your primary focus should be on lifting weights. I would recommend lifting weights and doing HIIT on separate days. Most HIIT exercises like running, cycling, rowing, and elliptical stress the lower-body more than the upper-body. In order to build your upper-body, it will be wise to add a weightlifting routine in addition to your HIIT workouts. You should not do HIIT and weightlifting on the same day because you want to allow your body (24-48 hours) to recover from a strenuous HIIT session before training again. Intermediate and advanced athletes can workout multiple body parts on the same day, but their second workout (whether HIIT or resistance training) will be less efficient and more difficult.

What should I eat after doing HIIT?

Eating for recovery after a HIIT workout is similar to eating after any workout. You should include a combination of proteins, carbohydrates and fats. My favorite protein-rich meals are eggs with sweet potatoes, chicken and brown rice, or grass-fed beef with spinach and tomatoes. I also like to snack on almonds and Greek Yogurt throughout the day. The combinations are endless. If you have additional questions relating to nutrition or supplements, you can email us or check out the articles at Examine.com.

What should I drink after doing HIIT?

Drinking water throughout the day to stay hydrated is necessary to prevent injury. Generally, eight glasses of water in a day are recommended to stay hydrated, but if you are working out, you will also need to replace what you sweat out. Sports drinks provide electrolytes to help you rehydrate quickly, but can also be loaded with sugar, so they should not be recommended for anyone trying to lose weight. An easy way to replicate the effects of a sports drink is to add a pinch of sea salt to your water after you workout. Salt helps your body absorb and retain water.

How can I stay motivated to workout for the long term?

Motivation is a false hope for maintaining an exercise program for the long-term. Most people are very motivated to start working out every January, but their motivation deteriorates by March as new responsibilities take up more of their time and will-power. 

What activities are you able to do consistently? Sleeping. Washing up. Brushing your teeth. Making your bed. Eating breakfast. Showering. Taking the same route to work everyday. What is the secret to maintaining these activities? They have become engrained in you as a habit. The secret to making exercise a part of your daily life is to understand how to turn it into a habit.

How can I turn exercise into a Habit?

In The Power of Habit, Charles Duhigg states that the three elements of the Habit Loop are:

  1. Cue

    Have a trigger that makes you to take action (i.e. put your running shoes next to your bed which cues you to workout when you wake up);

  2. Routine

    An action that is the result of the trigger (i.e. you see and wear your running shoes to go for a run first thing every morning).

  3. Reward

    Your brain experiences the benefits of this action (i.e. you feel an endorphin rush and eat a protein-rich breakfast)

What is a good morning routine?

Tasks: Wake up, fix bed, wash up, brush teeth, workout, eat breakfast, Vitamin D, Fish Oil, cold shower, and off to work.

Description: My morning routine is to wake-up at 6:30am, fix my bed, wash up, brush my teeth, then start my workout by 7am. I finish my workout, eat breakfast, shower and get ready to conquer my day. Working out has become a natural habit for me because I treat exercise like any one of these morning activities. It is something I need to do whether for 15 minutes or one hour.I also know that I have the most energy and will-power first thing in the morning and will complete those tasks efficiently. Find the best time that works for you and keep that time scheduled throughout the week. If you can make 15 minutes for exercise (whether in the morning, afternoon, or evening) and understand the three elements of the Habit Loop, you will be well on your way to conquering the psychological aspect of exercising for the long-term.

What is a good afternoon routine?

Tasks: Prepare lunch, eat, drink water, walk outdoors around the office, grab snacks, and go back.

Description: My afternoon routine is to prepare lunch at 12pm, finish eating by 12:30pm, grab a water bottle, go walking outdoors for 10 minutes under the sun, then come back to my office before 1pm. This is an easy way to restart my body in one hour while getting Vitamin D and light exercise in the middle of my day. Working out in the morning does not eliminate the need to get out of the office and move under the sun during the rest of your day. I also try to bring back almonds or healthy snacks with me to help me last through the rest of the afternoon.

What is a good evening routine?

Tasks: Workout/Walk, family dinner, warm shower, rest, eliminate blue light sources, stop using laptop, stop drinking water, read and sleep. 

Description: If I did not workout in the morning, I will try to go to the gym or outdoors right before dinner around 7 or 8pm. If I did a workout, then I’ll either go walking or jogging to destress after work. Then I will eat dinner with my family, take a warm shower, rest and get back online for a few more hours. During the work week, it’s difficult to stop staring at the computer screen all through the night for a project or emails. Make sure to download f.lux so that you can eliminate blue light sources from your laptop and your phone. I try to stop drinking water and put away my laptop one hour before I go to sleep (even if I don’t make it most nights) and then read a book until I fall asleep.