When it comes to stripping body fat, HIIT cardio is the way to go.
You will burn more fat, in less time, and even with less workout frequency. (1)
But what is the best interval length for fat loss?
Should you be doing 30 second bursts? Or how about 1 minute on, 1 minute off? Heck, what about the old 20 seconds versus 10 seconds of rest?
If you walk into any gym, you’ll see people doing countless variations of HIIT and all swearing it’s the “best” for results.
From the guy who always seems to be on the treadmill no matter what time of day you train, to the guy who smashes the elliptical like an angry jockey.
So today I’m going to give you a definitive answer to this question, using the latest science surrounding high intensity interval training.
This is an article I have wanted to publish for a little while now, because if you ask the question “How long should my HIIT intervals be for maximum fat loss?” in any gym, you will be met with a lot of conflicting information which can set you on the wrong track.
A lot of people using what I call a HIIT & Hope Mentality – i.e. going through the motions, not really progressing like they want to.
The Key Contenders
There are several different forms of high intensity interval training, including but not limited to:
- Tabata HIIT
The Tabata principle is based upon the concept of an 8 minute workout, revolving around 20 second bursts at maximal intensity followed by short 10 second rest periods. repeated for time.
Back in 1996, Professor Tabata and his team of researchers published a study which changed the fitness game forever. (2)
In the study, they took a group of elite athletes and subjected them to the training protocol you see above. The results were simply astounding – an increase in the VO2 MAX (considered the best measure of cardiovascular fitness) of 28%!
Given that the participants were elite athletes, and results are typically much harder to come by at this level, this study had a huge impact on the fitness industry and it has been a mainstay of interval training fitness plans ever since.
- Timed HIIT
Timed HIIT is the most commonly used form of high intensity interval training.
You’ve probably heard people telling you to do something like “30 seconds on, 30 seconds off, for an 45 minutes”, right? That’s timed-style HIIT.
It’s mainly popular because most cardiovascular machines come equipped with this style of program built-in to the features.
- Insanity style
If you’ve ever left your television on late at night, you’ve probably woke up the next morning reciting the f**king script to these annoying infomercials one time or another.
But aside from the hype, Insanity is a good fat loss workout.
The key difference between Insanity and other forms of HIIT is that Insanity focuses on much longer intervals of up to 3-4 minutes, interspersed with relatively short windows of recovery. Click here for a post on Insanity vs HIIT.
- HRM HIIT
HRM stands for heart rate manipulation.
HRM-based HIIT asks for 10-30 seconds of maximal intensity work, with rest periods as long as necessary for your heart rate to return to normal levels.
The total workout length with this style of training is typically around 30 minutes, and the idea is to increase the number of bursts you are able to perform over time (as less rest is needed when fitness levels begin to improve).
These methods are all very popular forms of high intensity interval training, and guess what? They will all get you fat loss results.
But there is a winner.
The Best Interval Length For Fat Loss
Let’s look at some of the latest clinical studies.
A team of researchers from the University of Nebraska published a study in the Journal of Strength and Conditioning Research concluding that 30 second bursts are superior for fat loss based HIIT, even out-performing intervals lasting as long as three minutes. (1)
That’s right. 30 seconds.
These findings support data published in a 2011 study from University of Ontario, Canada, where researchers also concluded that 30 second interval bursts were able to burn over twice as much body fat as regular cardio.
The Real Key To Great Intervals
The “trick” here is to get your rest period right.
You see, getting the maximum benefit from HIIT is about heart rate manipulation.
If you have tried interval training before, you probably know that (regardless of which method you use) the main instructions are to ramp up your intensity for a period of time before taking your foot off the pedal.
Well, we want to be achieving this same up/down system inside your body, too.
In the Ontario study, researchers were keen to point out that subjects were forced to take a recovery period of up to 4 minutes after every 30 second burst. This recovery phase was deemed crucial to the overall effectiveness of the workout. (2)
Because by ensuring adequate recovery, every 30 second burst was performed to true maximum intensity.
Despite performing fewer total interval bursts, this defeats the concept of performing “30 seconds on, 30 seconds off” because that idea doesn’t take into account the heart rate factor. There is no point beginning your next interval burst if you are still gassed from the one before.
Consider it the same as trying to hit a new squat PB without taking the necessary rest between sets.
Why It Works
The constant up/down nature of a proper HIIT workout wreaks havoc on our body’s energy systems and kickstarts the much hyped “Afterburn Effect.”
Otherwise known as EPOC, that’s the phenomenon which causes us to accelerate fat burning for up to 14 hours.
It’s the main benefit of HIIT.
But by not allowing proper recovery between intervals you do not fully engage said “Afterburn Effect.”
In order to maximize your return from HIIT, you need to perform each burst at as close to your maximum intensity as possible.
You do this by allowing your heart rate to properly recover between bursts.
Both studies above concluded that the greatest fat loss results were obtained when subjects performed a HIIT workout consisting of six 30 second bursts, giving a total workout time of around 30 minutes.
In both studies, the participants used recovery periods of 3-4 minutes between each burst.
This recovery period will differ from person-to-person depending upon your fitness level, so I’d recommend trying a 3-4 minute recovery period in your first workout and then shortening or lengthening it based on your own needs.
So, while HIIT is generally productive no matter which form of it you use, if your goal is to get the best interval length for fat loss then this would be a good place to begin:
- 30 second bursts
- 3-4 minute recovery phase (depending upon fitness levels)
- 30 minutes total workout time
And to maximize fat loss results, use these two rules:
- each interval should be performed as close to maximal intensity as you can
- if you’re still wrecked from your last interval, take more recovery time
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- Trembalay, A., et al. Impact Of Exercise Intensity On Body Fatness And Skeletal Muscle Metabolism. Metabolism, 1994; 43(7): 814-8.
- Tabata, I., et al. Effects Of Moderate Intensity Endurance And High Intensity Intermittent Training On Anaerobic Capacity And VO2 Max. Med Sci Sports Exerc. 1996 Oct;28(10):1327-30.
- Zubiga, J.M. et al. Physiological responses during interval training with different intensities and duration of exercise. J Strength Con Res; May 2011; 25(5): 1279-1284
- Macpherson, R. E., et al. Run sprint interval training improves aerobic performance but not max cardio output. Med Sci Sports Exerc. 2011 Jan;43(1):115-22.