You Need H.I.I.T, Here’s Why

HIIT stands for High Intensity Interval Training and it is a method of exercise which involves short bursts of maximum intensity activity with brief periods of rest between them. There are various approaches and brands associated with HIIT but they all follow a simple principle of short intense work with short rests to maximise the efficiency of your workout. For example, you might workout for 50 secs with a 10 sec rest period 30 times making your workout just 30 minutes in duration.

And here’s why HIIT is such a popular form of exercise:

Lack of time is one of the most cited barriers to exercise participation.

HIIT is time-efficient and it can provide you with comparable benefits to longer duration moderate training and endurance training. Because of it’s short duration people are simply more likely to do it and not only does it give you physiological benefits, it leaves you feeling mentally refreshed too….

AND there’s a huge body of evidence backing this up.

Some well-evidenced health benefits of HIIT are:

  • More efficient use of oxygen by muscles comparable to endurance training, i.e. increased V02 max (1)
  • Improvements to blood vessel and heart function comparable to moderate intensity exercise (2)
  • Improved insulin sensitivity (good for keeping your blood sugar in check) and metabolic function (3)
  • Improved cardiovascular function comparable to and in some cases superior than moderate intensity exercise (4)
  • Increased mitochondria size and number (the ‘batteries’ of your cell, these are powerhouses for all cell function) (5)
  • Increased fat burning compared to lower intensity training with just a few weeks of training (6) (7)
  • Post-exercise calorie expenditure- so you keep burning carbohydrates and fat after you stop working out (8)

Put in the terms that speak to a lot of people, HIIT can help you burn calories efficiently and burn more fat. It will strengthen and tone muscles while improving your cardiovascular health. So, it’s good for the inside and the outside.

And of course, there’s the mental aspect.

Psychologically, HIIT feels like less of a commitment and participants report enjoying it more than longer and lower intensity training sessions. Recent research found that workout programmes of a shorter duration are more adhered to than those which take more time (9) and participants tend to enjoy them more (10).

Never mind the huge body of scientific evidence backing up the benefits of HIIT…take my word for it, once you HIIT you never go back!

We all know those weeks when you don’t know how you would be able to fit in exercise. You’re snowed under at work and get home exhausted. The nights are drawing in and all you want to do is sleep. Maybe you have kids to look after. Well, you can do HIIT on your bedroom/living room floor. All you need is some pre-planned exercises and a stop watch. You can use YouTube videos or google some exercise ideas. You can use a HIIT timer app on your phone or computer where you set the duration of workouts and rest and number of reps.

I promise you that even when you’re tired, just 20 minutes will make you feel better and you’ll be proud of yourself for doing it. Once this becomes a habit you’ll wonder how lack of time was ever an excuse!


1. Burgomaster KA, Howarth KR, Phillips SM, Rakobowchuk M, Macdonald MJ, McGee SL, Gibala MJ, 2008. Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans. J Physiol.
2. Gibala MJ, Little JP, Macdonald MJ, Hawley JA.2012. Physiological adaptations to low-volume, high-intensity interval training in health and disease. Journal of Physiology.

3.Hood MS, Little JP, Tarnopolsky MA, Myslik F, Gibala MJ. 2011. Low-volume interval training improves muscle oxidative capacity in sedentary adults. Medicine and Science in Sports and Exercise.

4. Helgerud, J., Høydal, K., Wang, E., Karlsen, T., Berg, P., et al. (2007). Aerobic high-intensity intervals improve VO2max more than moderate training. Medicine and Science in Sports and Exercise, 39(4), 665-671.
5. Gibala, M. (2009). Molecular responses to high-intensity interval exercise. Applied Physiology, Nutrition, and Metabolism, 34(3), 428-432.
6. Perry, C.G.R, Heigenhauser, G.J.F, Bonen, A., and Spriet, L.L. (2008). High-intensity aerobic interval training increases fat and carbohydrate metabolic capacities in human skeletal muscle. Applied Physiology, Nutrition, and Metabolism, 33(6), 1112-1123.
7. Talanian, J.L., Galloway, S.D., Heigenhauser, G.J, Bonen, A., and Spriet, L.L. (2007). Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women. Journal of Applied Physiology, 102(4), 1439-1447.
8.  LaForgia, J., Withers, R.T., and Gore, C.J. (2006). Effects of exercise intensity and duration on the excess post-exercise oxygen consumption. Journal of Sports Science, 24(12), 1247-1264.

9. Jung ME, Bourne JE, Beauchamp MR, Robinson E, Little JP. 2015. High-intensity interval training as an efficacious alternative to moderate-intensity continuous training for adults with prediabetes. Journal of Diabetes Research.

10. Jung ME, Bourne JE, Little JP (2014) Where Does HIT Fit? An Examination of the Affective Response to High-Intensity Intervals in Comparison to Continuous Moderate- and Continuous Vigorous-Intensity Exercise in the Exercise Intensity-Affect Continuum. PLoS ONE 9(12): e114541. doi:10.1371/journal.pone.0114541


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