Why You Should Be Doing High Intensity Interval Training (HIIT)

A major trend in the fitness industry globally is the idea of High Intensity Interval Training, which is referred to as HIIT.

HIIT methods have been an essential part of athletic training programs since the early 19th century due to how closely connected it is linked with specific sports training intensities.

HIIT training programs can be easily modified to suit people of all fitness levels and can be performed in just about all exercise modalities, including but not limited to:

  • Running
  • Cycling
  • Swimming
  • Cross training
  • Body weight and free weight exercises

HIIT training is continuing to grow in its popularity, and for good reason. It seems simple, but science is proving that incorporating a couple of HIIT sessions into your regular training routine can have major health benefits.


What Is HIIT Training?

HIIT is a training technique, which involves intense bursts of high intensity exercise followed by varied periods of low intensity or complete rest.

When developing HIIT programs, the relationship of both the work and recovery interval is extremely important.

You must consider the duration, intensity and frequency of both the work and recovery intervals.

The intensity during the work period should be greater than 80% of estimated max heart rate (the higher the better – it should feel like you are exercising “hard” to “very hard”). Your maximum heart rate can be roughly estimate by subtracting your age from 220. For example if you are 35, your maximum heart rate is around 185 (220 minus 35).

The intensity of the recovery period should be less than 50% of your estimated max heart (rest or active recovery – prepares you for next working interval).


Session duration and Interval timing:

The length of HIIT programs can range from 30 min all the way down to 4 min (commonly known as Tabata Training). You must consider the ratio of work to rest. Remember the key is to work as hard as possible during working phase and recover as best as possible before the next working set. If you do not allow yourself to recover and decide to take shorter rests periods you could be limiting the effectiveness of this training method (EPOC – explained in detail below).

A few variations can include work : rest ratios of 1:3, 1:2, 1:1.

It all depends on how long and how intense the session is.


Recovery is vital:

While HIIT workouts may be very short, they are more exhaustive then steady state exercise. Therefore, a longer recovery period is often needed before starting your next session. If you are fatigued and not fully recovered you will find yourself not working as hard in the session.

Research recommends two HIIT sessions a week, making sure you spread both workouts throughout the week. If you are a complete beginner consider starting with one session per week and when you feel ready, add a second HIIT session for a greater challenge and faster results.


Each year HIIT is becoming an increasingly recognised and well liked method of training.  If HIIT training is incorporated into a well-balanced program it can optimise the development of numerous health and fitness goals.


Major benefits of HIIT Training:

Here is a summary of some major benefits of what one HIIT session could do for you:

  • Burn more calories in least amount of time – 10 min HIIT vs 45 min steady state walk. Which would you prefer? (Get more results and train for less amount of time)
  • Quick and convenient – super efficient HIIT session can be ideal for a busy schedule (fit more in your day)
  • Increased metabolism for short period of time – burn more calories in less time (refer to EPOC effect in next paragraph)
  • Both aerobic and anaerobic fitness gains
  • Increased cardiovascular health
  • Increased insulin sensitivity – helps exercising muscles use glucose for fuel to make energy (using glucose for fuel during exercise is key to training harder and burning more fat at rest – again refer to EPOC)
  • Lower cholesterol
  • Lower abdominal fat and weight loss


EPOC – Excess Post-Exercise Oxygen Consumption

A HIIT workout (training “very hard”) increases the body’s need for oxygen during the working phase. This then causes your body to ask for more oxygen during recovery.

If you can increase the amount of oxygen during and after a workout, you can increase the amount of net calories burned.

This is what is called the EPOC (Excess Post-Exercise Oxygen Consumption) effect and is the main reason why intense exercise in short bursts will help burn more calories (especially fat) then your regular steady state exercises.

Due to the vigorous nature of HIIT workouts, studies show that over a 2 hour period after exercise you can be burning 6-15% more calories above your initial workout energy expenditure.

The EPOC effect can also speed up your metabolic rate for up to 48 hours after a HIIT session. How long after the workout all depends on how hard you work with each working period.


High Intensity Interval training alsmost sounds too simple to be true, however the large body of scientific evidence supports the claims that HIIT training really is one of the most effective ways to get better fitness results in less time.



  • Bersheim E. and Bahr R. Effect of exercise intensity, duration and mode on post-exercise oxygen consumption. Sports Medicine, 2003.
  • LaForgia J., Withers R. and Gore C. Effects of exercise intensity and duration on the excess post-exercise oxygen consumption. Journal of Sports Sciences, 2006.


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Author: CrankIt Fitness

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