Medium Intensity vs High Intensity Interval training

As I scroll through my Instagram feed, I see people bragging about their morning sessions with images of smart watches displaying heart rates and calories burned and #smashed #hiit #blahfuckingblah and I feel like it’s time for a post.

It is no secret that due to a multitude of factors in modern times we are getting more and more time poor. With the decrease in leisure time means our time committed to exercise and getting us healthy must be targeted and effective.

Hence the rise of High intensity interval training. High intensity interval training (HIIT) has its roots right back in the 1950s with Sprint coaches using it in on their sprint athletes with 100% HR intensities to yield quick adaptations to baseline fitness so they could spend more time on max velocity efforts.

Let’s investigate further and dive in to what HIIT means and when it is most effective. In essence HIIT is when your heart rate must reach 85% and above for a prescribed time (not long) of anaerobic exercise immediately followed by rest interval. To put simply you work incredibly hard for a small-time window followed by a quick rest for it all to happen again and again. These workouts if done correctly usually cannot go for too much longer then 30-40mins.

This in lies my gripe, too many fitness organisation/clubs’ market this type of training on their timetables only for it to be done incorrectly be it on purpose or by lack of education. How do I know other organisations are doing this wrong? Well, the biggest tell tail, is the time on the watch. Usually includes 400cals in 1:00:46 or whatever along those lines.

The whole purpose of high intensity exercise is that its consistently so high you cannot sustain it for long periods as exhaustion comes on quite quickly. If you reach this point, it incurs an adaptation process on the body. During this adaptation phase your body burns calories as it increases all the metabolic processes needed to prepare it just in case you do something like that again.

The benefit from this process means more cals burned during the exercise time but also well after the session finishes as your excess post oxygen consumption (EPOC) and adaptation processes are in overdrive. Another added benefit it means less time on the feet (reduced exercise time) meaning less likely to get hurt or have overuse injuries and the like.

Now if you are performing these so called “HIIT Classes” at some organisations and not getting to these levels of intensities then you aren’t doing HIIT but rather an amalgamated version of HIIT and aerobic work. Meaning sure you will burn cals and have some training stimulus for you to adapt to but you won’t get the same post exercise adaptations you would get if it were truly a HIIT session. Meaning sure its not bad and we all encourage people to get at it and get moving, but keep in mind that when someone or a place says its HIIT be ready to give it your all. If the class doesn’t dictate that effort than you can say well…..that wasn’t HIIT.

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