What is High Intensity Interval Training- HIIT- and why it's legit?

Sunday, December 14, 2014. Author Dr. Dan Reardon

What is High Intensity Interval Training- HIIT- and why it's legit?

HIIT combines ‘intervals’ of low-intensity exercise with intervals of very high-intensity exercise (95–100% effort). So, for example, you might run at just about full speed for ten seconds to one minute, and then jog or walk for 30 seconds all the way up to four minutes (more on ideal interval times and exercises later). At the core of HIIT is that activity has to be at a maximum or near-maximum level of effort for a short time, followed by activity that is of long enough duration and low enough intensity that it allows enough recuperation for the next very intense ‘work’ interval. So it’s basically the opposite of low intensity, steady state cardio (LISS). Instead of a steady pace throughout, HIIT has you working at full tilt in short bursts, each followed by very relaxed ‘active rest’ periods. The key consideration (because most people get this part wrong) is getting your rest times right and not being tempted to start the next interval too soon—you need to get that breathing rate and heart rate down so you’re able to put enough work into the next interval!

The most important attributes of HIIT are that you spend far less time exercising and yet the result is substantially greater fat loss and probably better maintenance of muscle tissue as compared to cardio. So for the price of a few short bouts of extremely demanding activity, you’ll spend less time exercising, yet get superior results!

Let me just summarise HIIT…

HIIT (High Intensity Interval Training) involves training at a very high intensity in an interval format. There are tonnes of performance-based benefits you get with HIIT because of the skeletal muscle changes similar to that of endurance training. The reason it has such acclaim this day in age is because we now know that HIIT is great for burning body fat.

Here’s why…

When you have lots of oxygen around, your body uses aerobic energy pathways. When oxygen runs out, it uses anaerobic energy pathways. HIIT is an anaerobic form of exercise that seems to help boost metabolic rate by increasing something called EPOC (Excess Post-Exercise Oxygen Consumption), and also possibly increases the VO2 max, which allows the body to process more calories and oxygen.

When you create an oxygen debt, as represented by the EPOC, your body has burnt off all available sugar, so it starts to burn fat. As a result of HIIT, your body burns fat and continues to burn fat for many hours after the training session. And that’s really the basis of it.

So what does this have to do with genes and DNA?

Well I’m pleased you asked that. We test for genes that tell us how easily you burn fat. There are some genotypes where switching from carbohydrate to fat metabolism is not that easy. For these people, burning fat can be really difficult, so they need to be doing HIIT as part of their fat loss training, unquestionably. We can even give these people an idea of the amounts of HIIT they should do.

Pretty impressive, right?

But what do you expect, as I’ve said this time and time again: your DNA is a blueprint. If you understand your DNA and decipher it appropriately, then you literally have a road map to your goals… even surpassing your goals!

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