As previously discussed, high intensity interval training (HIIT) is hard, but not maximal exercise. In fact, a more robust definition of HIIT includes any training program that targets training intensities between 80-100% of peak heart rate. Typically, HIIT programs utilise bursts of activity that last between 1-4 minutes, that are key word “within” the individuals aerobic capacity. So in short, HIIT training is sub-maximal, but strenuous exercise (Keating et al. 2017). Write now, if you were to write down the exact details of your HIIT sessions, would they tick the following boxes:
- A working intensity between 80 – 100% of your clients predicated maximal heart rate?
- Contain a work interval between 1 to 4 minutes, anything shorter may encourage higher intensities to be attempted?
- Set work to rest periods?
- Contain a set amount or volume of work – think reps/sets?
- Performed with appropriate rest in mind, i.e. not every day?
Hopefully you ticked a few of these boxes? To help make my point a little clearer, I pulled this HIIT workout of the internet to highlight a few important points:
On the surface, this looks like a very typical HIIT workout we could expect individuals to be following in fitness settings worldwide, it contains a set work and rest format and also it sets some boundaries for the total amount of workout time, all good. It also contains, one very important piece of information that helps us distinguish this program from a sprint interval training program? Did you identify it? If you noticed, this HIIT program sets the working intensity via a 1-10 RPE scale at 6-7 or more simply put they set a working intensity, then you should be very happy with yourself for picking that up, as many would have missed this!
While this is a much better example of a HIIT program, than the many 100’s you can find on a simple google search, it is important to be aware, that unlike this example, most HIIT workouts posted on the internet do not describe what the working intensity should be! Which, in this case if the authors did not describe the subjective intensity, via a rating of perceived exertion (RPE), it could leave an unsuspecting person to attempt to do the 30-second effort at a supramaximal intensity, usually the shorter the interval, the higher the intensity also. This is why intervals of 1-4 minutes are often recommended. On a final, and interesting note, when it comes to fat loss, HIIT has not been shown to be any more effective than a standard continuous, steady state exercise program, which may come as a shock to many people. Taken together, the important take home messages from this post is to consider just how you are putting together your HIIT workouts, consider putting a more detailed framework around your sessions, which includes a total workout time or length, exact working intensities, with appropriate rest intervals and finally, consider like other exercise modalities an element of periodisation, so your clients are not exposed to this vigorous form on an extended basis, without adequate recovery.