High Intensity Interval Training - HIIT:
Fact and Fiction

High Intensity Interval Training (HIIT) has been highly acclaimed to help burn fat and is probably the most recommended form of cardio for those who want to burn fat without having to spend hours at the gym.

The questions are, first what is HIIT and second, does it really do all it’s claimed to? After all, some people are claiming HIIT is nine times as effective as steady state cardio – and that’s a lot!

HIIT is a form of cardio training. The difference between it and normal cardio is the intensity and duration. HIIT training consists of short bursts of high intensity activity punctuated by short periods of rest.

Here’s an example of a 4 minute HIIT workout for beginners:

This routine looks very attractive to those who spend hours on the treadmill, but the intensity levels are high. Sprinting is defined as running as fast as you can for 30 seconds. Not recommended for those with heart conditions or the seriously obese.

As you get accustomed to these workouts, your time must be increased. The same interval of 30 seconds jogging followed by 30 seconds of sprinting is used, you just add more overall minutes – up to about 15. Only two sessions per WEEK are needed for beginners. That’s a total of 8 MINUTES cardio. Not bad, yes?

Here’s an example of how to add time to your HIIT workout:

Note that jogging/sprinting is just one model: HIIT can be applied to all types of cardio equipment and exercises – elliptical machines, treadmills, bikes, swimming etc…

Note that treadmills are slow to change speeds so timing your workout can be difficult, but it’s still possible.

The key to make it work is intensity - real intensity. Like resistance training, the work you put in equals the benefits you get out of it. People who loll around the gym barely breaking a sweat will get the same benefit from HIIT as the rest of the exercise they do – zero.

For those that are beginning an exercise program, older persons and the very obese, HIIT programs might not be the best idea.

Because the intensity needed is high, so is the risk for injury. But it’s not that much more risky than say, running every day. Its high impact, but also very short term, so the risks for injury are fairly balanced. Since you are only going for a maximum of 15 minutes, you don’t do the long term “pounding” that, for example, running does. But it’s nowhere near as safe as brisk walking or power walking.

Also, you only do HIIT twice a WEEK to make it even better in terms of giving you a long recovery and rest periods. Can you actually burn more calories with HIIT? The answer is probably not. However, you may be able to burn the same amount in less time.

Here’s why: HIIT burns calories two ways – first it burns huge amounts because of the very high intensity even given the short duration. Second – and this is less proven, but still claimed – is that extreme stress provokes a response from your body that includes a higher metabolism throughout the day. Also, sprinting in particular is known to raise hormone levels that encourage muscle growth – perfect for body builders and one of the principal reasons they use HIIT. More muscle also increases your metabolic rate which in turn burns more calories.

This second effect is where many disagree and it has been hard to measure. In some studies, it seems to have little effect - in others, none.

If you really want to burn very large amounts of calories, nothing beats an hour of any cardio exercise at medium intensity. Not relaxing, mind you – but sweating hard throughout. You can burn anywhere from 500 to 900 calories – depending on your weight – and this can be repeated 5 times per week giving you a total of 2,500 to 3,500 calories burned per week.

Contrast that to HIIT programs where even 2 sessions of 15 minutes per week at high intensity will only burn from 300 to 600 calories. Add this to the secondary effects and you still will not even get near the 2,500 mark. Increasing the number of HIIT sessions will help, but you still you’d probably need to do it every day which would increase your risk of injury and is not recommended.

So if your principal goal is to burn off large amounts of body fat, go with steady state cardio like brisk walking, using the elliptical machine and stationary bike or any other moderate intensity, long term aerobic activity.

However, if you want to increase muscle mass and don’t have problems keeping the fat off, HIIT may make sense - if you are a body builder, even more so. Adding a few HIIT sessions to your regular cardio workout is not a bad idea either, but don’t do both types on the same day unless you plan to try out for the Olympics.

But for those who just can’t seem to get rid of fat no matter how hard we try, doing less – even at great intensity – will not give the same benefits as doing more. Simple, right?

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