High Intensity Interval Training (HIIT)

By now most of you will have heard of High Intensity Interval Training, or "HIIT" for short. It is easily one of the most popular fitness trends at the moment, and for good reason. We explore what HIIT is and why it is so effective...

What is HIIT?
HIIT is a training technique that has you push yourself at "all out", or near maximal intensity for a short period of time, followed by a short period of rest, which is then repeated for multiple intervals. Here's an example:
- Fast run for 4 minutes (so you are struggling to sustain much longer)
- Recovery walk (low intensity) for 4 minutes
- Repeat 4 times

This style of training puts a large stress on your cardiovascular system and increases your body's need for oxygen during the effort phase creating an oxygen shortage. This shortage tries to replenish itself during the recovery phase, however due to the short nature of the recovery the system doesn’t have time to recover fully before the next interval. This after-burn effect is known as Excess Post-Exercise Oxygen Consumption or “EPOC” and is the reason to why this style of training is great for boosting your fitness and helping with weight loss.

"I'm not sure I'm fit enough for HIIT"
This is a common concern. High intensity can be measured several ways including oxygen consumption, heart rate or just simply your perceived level of effort. If you find an exercise "hard or very hard", that is high intensity. One person's high intensity bout may be 800m sprints, another's may be walking slightly quicker than normal. You can also change the nature of your "rest break", duration of your intervals, the amount of intervals, and even the style of exercise. Here's some other examples of HIIT...
- Walking, running or cycling incorporating some hills
- Circuit training
- Team sport
- Dancing - one song on, one song off
- Up and down stairs at work
- and good old fashioned sprints in the park

Is it safe?
In the large majority of cases, yes. There is growing evidence that HIIT is not only safe for healthy people, but can be safe for many chronic diseases. Add to this the health benefits of HIIT, I'm sure we'll see this as a mainstay of training techniques and not just a fad for the elite. However, if you or your doctor are uncertain if HIIT is safe for you, consult an Exercise Physiologist.