How you can benefit from High Intensity Interval Training (HIIT)

HIIT, besides being the number 1 fitness trend last year (2018), is still dominating fitness podcasts, local gym timetables and my personal training schedule. You will struggle to find a group fitness timetable without the initials HIIT etched into it somewhere. If you’ve been following my Instagram or YouTube channel, you’ll see that I’m certainly on board, posting weekly HIIT workouts to continually give you fresh ideas for HIIT workouts you can incorporate into your busy week. Here’s a recent example.

Why have we gone HIIT crazy?

HIIT, an acronym for High Intensity Interval Training, is not a new concept. The idea is that you perform an exercise that is going to push your heart rate up to near maximal level, rest and repeat ad libitum. In most of my own HIIT workouts the work interval is just long enough to get close to a maximal or near-max intensity. The rest period is then sufficient to allow a slight recovery but never a full recovery meaning it will take less time to reach that same near-max intensity during the next work interval. A HIIT workout will always have set rest intervals rather giving you small micro rests as you move from one exercise to the next in a typical circuit or crossfit style workout.

Optimal Work & Rest Times

Depending on the exercise, I find between 30 seconds to 1.5 minutes is usually sufficient work time to reach the desired heart rate, but there are many variables to take into account when setting the work time – the speed of the movement, the resistance being applied and the rate of perceived exertion (the RPE) required for a single rep of the given exercise. An exercise with a higher RPE for one rep would require shorter work interval. Similar to the work interval, required rest periods will depend on the intensity of the exercise and how long I spend at a near maximal intensity also generally around 30 seconds to 1.5 minutes. However, in the video above I used a tabata timer consisting of 20 seconds work and 10 seconds rest with longer rest periods at the end of a completed set.

I prefer to use a combination of strength based movements with no more than 50% of the load I would lift during a typical strength workout, that way I can do a high number of reps and continue with good form even when I’m gasping for breath. That’s the essence of HIIT work, repeatedly getting yourself into a state where you are gasping for breath. I often combine the strength movements with a variety of aerobic exercises such as skipping, spinning and running. Depending on your physical abilities and current level of fitness, the required exercise difficulty will vary from person to person.

The benefits of HIIT

The benefits of engaging in HIIT are numerous but I’ll list three key reasons that I believe provide enough evidence as to why everyone should be doing some form of regular HIIT.

HIIT increases your VO2 max

By training at a maximal intensity you are asking your body to adapt to this high physical output your week now requires. You adapt. You get stronger. One of the ways you do this is by increasing your capacity to transport and utilise oxygen in the energy creation process and subsequently the efficiency in which you can remove the metabolic byproducts of intense exercise – think lactic acid. In doing so life gets easier. Having a higher VO2 Max better enables you to adjust to the demands of your day. A set of stairs to climb – no breath shortness here, running late for the train – I’ll just jog and make it on time, playing with my kids on the floor – I’ll wrestle till they get bored (well maybe that’s a stretch, we all know wrestles end with tears and not boredom).

HIIT helps improve insulin sensitivity

Without going into a lot of detail about insulin sensitivity, simply know that whenever we eat foods which cause our blood glucose levels to increase (yep, that’s you doughnut) insulin is the key player which helps clear the excess glucose from our system. Excess blood glucose is toxic to our bodies so we need to efficiently convert it to glycogen (storage form of glucose) or fat, another handy storage form of energy. Glycogen stores are limited and there is only so much we can store. HIIT training leads to the breakdown of glycogen to be used as energy. When you inevitably enjoy that next carbohydrate feed, you now have available storage space in your liver and muscle tissue where you can push the excess blood glucose without adding to the other storage area, commonly known as the “love handles.”

HIIT increases your metabolism

Firstly, why is increasing metabolism a good thing? Metabolism is essentially the speed at which we can create and break down molecules within our body. To learn more about metabolism from a previous post, click here. Increasing your metabolism means your body is more efficient at carrying out the processes involved in breaking down food, producing energy, building hormones, repairing and building muscle, maintaining bone mineral density and the list could go on. My current stance on metabolic rate is it’s not just a matter of higher = better, however a majority of the population stand to gain considerably by increasing their metabolism, often resulting in weight loss and reduced lethargy.

To top it all off, not only will HIIT provide amazing physiological benefits, these benefits can be gained in workouts of 20 minutes or less making HIIT extremely time efficient. Knowing there are some major benefits to be gained from adding HIIT workouts into your week, are you on board the HIIT train?


Post by Russell Whiteford, founder of I GRASP Wellness. Russell is an experienced leader in fitness, wellness and sports coaching. With an undergraduate degree in Exercise Science and currently completing a Masters in Human Nutrition, Russell combines his theoretical knowledge with public and private sector experience in recreation, project management and high performance. All with the aim of bringing you thought provoking content to help you maximise your wellbeing, productivity and performance.