High intensity interval training

Exercise Workouts / Category / Emile Du Toit / May 6th 2014

Insufficient exercise and overeating leads to chronic illness

In modern society we choose to kill ourselves!

We live in a world where advances in medicine mean that we seldom die from the acute infectious and parasitic illnesses of the past. This means that most of our health issues tend to concern our body slowly deteriorating until we develop whichever chronic illness eventually kills us. A gloomy thought? Possibly.

In today’s world our level of health is now largely controlled by ourselves, not external factors. And yet sadly our response to this appears to treat our bodies as poorly as we possibly can.

Levels of exercise are on the decline just calorie consumption continues to rise. Too many people in society continue to prematurely bring on illnesses, despite the plethora of knowledge freely available on the internet that they are slowly killing themselves.

Low levels of physical activity in 1st world countries

A high percentage of people (particularly) in 1st world countries are hardly physically active or entirely physically inactive. In the USA well north of 40% of adults do not do any exercise, with another 30% doing a little but not enough to meet the minimum daily exercise requirements. This is despite the irrefutable and uncontested evidence that physical activity benefits men and women of all ages.

Exercise of higher intensity or duration adds additional health benefits

Significant health benefits can be derived from doing a moderate amount of exercise on at least half the days in a month. It has been shown that exercise of higher intensity and/or longer duration tends to bestow additional benefits over and above those gained by moderate exercise of short duration.

Exercise increases both life expectancy and quality of life

Physical activity has numerous physiological benefits, most notably in the cardiovascular and musculoskeletal systems, but also on the functioning of metabolic, endocrine, and immune systems.

Exercise has been demonstrated to significantly reduce the risk of premature mortality and morbidity in general. It is particularly helpful in delaying or preventing the onset of chronic illnesses such as coronary heart disease, hypertension, colon cancer, obesity and diabetes mellitus.

It is also necessary for the health of healthy bones, joints and muscles.

Exercise improves mental health

Exercise has also been shown to have great benefits in preserving mental health. It has been shown to be a highly successful way of reducing stress, as well as in improving mood and reducing anxiety.

Exercise is commonly used for weight loss

Many people often actually exercise primarily as a weight loss method, in order to decrease body fat percentage and enhance their physical appearance. The way I see it we need a range of different motivations on those rainy mornings when we need to drag ourselves out of bed and go do something healthy, and wanting to look great is as good as any. However, there are obviously people who take this to extremes, where the frequency and intensity of their exercise regime actually leads to deteriorating health!

Current minimum recommendations for exercise

Current recommendations for physical exercise are that people should exercise at least moderately (a minimum of brisk walking) for 30 minutes or more on most days for a total of at least 150 minutes of exercise per week. Approximately 22% of American adults currently meet these criteria.


This article guides you through to an understanding of high intensity interval training. It begins by delivering an understanding of interval training, and then takes a look at high intensity interval training. We take a look at how HIIT works, as well as the types of exercise that have been well researched in which HIIT can be utilised.

Interval training

Interval training is a method of training in which rest/low exertion, and higher exertion are alternated.

During higher exertion intervals the athlete performs at a specified level of performance, though below that of his peak performance. During the rest/low exertion intervals the athletes pulse has time to return to near normal levels and thus the athlete gets a chance to recover somewhat before the next higher exertion interval.

What is high intensity interval training?

High-intensity interval training (HIIT) is a performance enhanced form of interval training. It is an exercise strategy alternating periods of relatively short but very intense anaerobic exercise with less-intense recovery periods. These short, intense workouts have been shown to improve fitness (VO2 max), insulin sensitivity (glucose metabolism) and fat burning.


Why does it work?

Actually the more I read the more I realize that scientists are not too clear about some the reasons that it is as effective as it is. One part of the puzzle though is that when you are at maximum effort you are not just using your leg muscles but many other muscle groups including shoulders, arms and some of the stabilizers.

This means that around 80% of your muscle cells are being activated. Walking through to moderate intensity running or cycling only uses around 20-40% of your body’s muscles.

There are many studies showing the effectiveness of high intensity interval training, and often also comparing it favourably to endurance training. For example, a 6-session (2 weeks) study of HIIT demonstrated that subjects significantly increased their fitness levels.

In this study the time the HIIT subjects spent actually exercising was 10% of that spent by typical endurance training athletes, and the total time on the bike with HIIT was 25% of that spent while doing endurance training.

Where can one do high intensity interval training?

Actually, it can be done pretty much anywhere and with anything! Some of the areas that have been researched and where training programs have been constructed and tested include the following:

  • Running
  • Cycling
  • Circuit training using body weight as resistance: This is an interesting program utilising approximately 12 different exercises covering pretty much all the muscle groups. The athlete gets a 10-second break between apparatus, and the whole circuit takes around 7 minutes. It has been suggested that this circuit should be done 3 times. Since it utilises only bodyweight, it can be done absolutely anywhere!
  • This concludes this overview on high intensity interval training. We take a deeper look at HIIT in short duration high intensity interval training.


    1. King, Jeffrey W. A Comparison of the Effects of Interval Training vs. Continuous Training on Weight Loss and Body Composition in Obese Pre-Menopausal Women. (M.A. thesis). East Tennessee State University.
    2. Laursen, P.B.; Jenkins D.G. (2002). "The Scientific Basis for High-Intensity Interval Training: Optimising Training Programmes and Maximising Performance in Highly Trained Endurance Athletes". Sports Medicine 32 (1): 53–73.
    3. Perry, Christopher G.R.; Heigenhauser, George J.F.; Bonen, Arend; Spriet, Lawrence L. (December 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.
    4. Rozenek R, Funato K, Kubo J, Hoshikawa M, Matsuo A (2007). "Physiological responses to interval training sessions at velocities associated with VO2max". The Journal of Strength & Conditioning Research 21 (1): 188–92.
    5. Talanian, Jason L.; Stuart D. R. Galloway, George J. F. Heigenhauser, Arend Bonen, Lawrence L. Spriet. (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.
    6. Tjønna, A.E., Leinan, I.M., Bartnes, A.T., Jenssen, B.M., Gibala, M.J., Winett, R.A.,
      Abstra, U.W. (2013). ‘Low- and High-Volume of Intensive Endurance Training Significantly Improves Maximal Oxygen Uptake after 10-Weeks of Training in Healthy Men’. PLOS One
    Little, J.P., Safdar, A., Wilkin, G.P., Tarnopolsky, M.A., & Gibala, M.J. 2010. A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms. J Physiol.

    Motivation to exercise consistently

    Although there is such strong agreement that people should exercise, clearly it is not translating into increased exercise. Throughout these articles on exercise we will examine why this might be, and look at useful strategies to increase motivation to get out there on the road!

    Finding an exercise regime to best meet your idiosyncratic needs

    There is also a lot of controversy about which forms of exercise are most helpful. I do not see there as being a definitive answer here. My article on comparing HIIT to traditional and solely aerobic exercise programs discusses some of the choices available. I think personal choice is really important, as if you enjoy something then you are much more likely to stay motivated to do it.

    Equally, different exercise types are probably better for different sports, body types, fitness levels, personalities and even DNA structures!

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