Is High Intensity Interval Training Overrated? *Guest Blog Post*

Is High Intensity Interval Training Overrated? *Guest Blog Post* June 5, 2016Leave a comment

Short answer yes. That’s not to say that it is bad per se, but it has definitely been over-hyped by a lot of trainers and fitness professionals. Entire gyms have been built exclusively around HIIT and many trainers use it exclusively to train their clients.

HIIT is popular for two reasons, the first is that it is perceived as a big calorie burner. People performing it finish drenched in sweat and breathing hard. The second reason is that it is seen to be efficient, and it can be. Why spend hours slowly jogging around a park when you could be finished in just 15 minutes? Whilst getting the same results.

I have seen it time and time again with my clients, when they are sweating and out of breath they feel that they are getting better results from their sessions. But there is little scientific evidence to back this up. And in this article I am going to show you why.

Firstly, the benefits …

High Intensity Interval Training improves endurance [1], it can reduce body fat [2], it will burn calories even after you’ve finished exercising (known as Excess Post-exercise oxygen consumption or EPOC) [3], and can help reduce common causes of heart disease [4]. Pretty amazing right?

I am not here to argue that HIIT has no value, and personally I use it with some of my clients. The benefits mentioned above are correct and I don’t disagree with them, but here are the reasons why I believe it is over-hyped.

Whilst HIIT can improve endurance and reduce body fat, so can a lot of exercises. Resistance exercise can reduce body fat as effectively (if not more) [5]. As can regular endurance training (obviously). The benefits of HIIT are not unique, and they’re not anything special. You could recreate them with any long term exercise and diet strategy.

But HIIT is more efficient right? If five 30 seconds sprints can burn 200 calories then that’s much more efficient than a one hour run. But let’s actually look at this, according to a 1 hour run (at 5mph pace) burns 476 calories which is more than twice as many as those sprints burnt.

The issue is that, whilst the sprints only lasted 2 minutes 30 seconds in terms of actual exercise, they involved maximum effort. Which means that the runner would need to warm up fully beforehand (10 minutes or so) would have to rest in between each sprint (at least 5 minutes) and would be unlikely to be able to perform any exercise afterwards.

Because HIIT means putting all of your energy into those sprints. So those 150 seconds of intense exercise can take up to an hour to complete, and in that time the long-distance runner has burned 276 more calories. Not looking quite so efficient now is it?

But what about EPOC? That magical post-exercise calorie burning that HIIT gives us? Well, what happens to you after you do such an intense workout that EPOC becomes an issue? Your body starts to slow down.

If you’re anything like me you’re going to lie down on the sofa after this workout and you won’t be doing much afterwards. This is where a little thing called Non Exercise Activity Thermogenesis becomes an issue. NEAT as it’s known is basically the sum of all the calories you burn doing any activity there is, be it sitting down and fidgeting with a pen, or doing the washing up, walking, eating, cleaning, you get the idea.

NEAT can be responsible for hundreds of calories burned during the day, but the more fatigued you are the less NEAT happens as your body is trying to preserve energy. So you might be burning calories through EPOC but your NEAT will be down to compensate it.

Don’t get me wrong, this will be less of an issue the fitter you are. So persevering with HIIT will eventually give you those sweet EPOC induced calories without the lowering of NEAT, but my point is that HIIT may be more trouble than it’s worth for some. And getting an obese woman who has never exercised before to perform shuttle runs because you believe that they’ll burn more calories long term is moronic.

The main issue with HIIT is that most people are not fit enough to get any benefits out of it, you need to be sprinting as hard as you can for 30 seconds (x5) to burn those 200 calories and most people could not complete that. And if they did they would be in much greater danger of injuring themselves than their long-distance running fellows. In 2015 a study found that 63.8% of track sprinters had reported an injury compared to only 31.7% of longer distance runners [6].


I am not telling you to avoid HIIT like the plague, I am telling you that whilst HIIT has its place it is not for everyone. Nor is it required for fat loss. Fat loss is created by being in a calorie deficit, exercising regularly, and being patient/consistent. There are some strategies that are more effective than others but essentially any exercise program you follow has the potential to help you lose weight.

Matt Smith an experienced personal trainer based in Harrow, North West London, and as well as producing awesome content for the everyday gym goer to delve into, provides fantastic online coaching programmes that consistently get great results.

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[1] Gillen JB, Percival ME, Skelly LE, Martin BJ, Tan RB, Tarnopolsky MA, et al. (2014) Three Minutes of All-Out Intermittent Exercise per Week Increases Skeletal Muscle Oxidative Capacity and Improves Cardiometabolic Health. PLoS ONE 9(11): e111489. doi:10.1371/journal.pone.0111489


[3] Gillette, C., Bullough, R., Melby, C. 1994. Postexercise energy expenditure in response to acute aerobic or resistive exercise. International Journal of Sports Nutrition 4(4): 347-60

[4] Tjonna, A., Stolen, T., Bye, A., Volden, M., Slordahl, S., Odegard, R., Skogvoll, E., Wisloff, U. 2009. Aerobic interval training reduces cardiovascular risk factors more than a multitreatment approach in overweight adolescents. Clinical Science 116(4): 317-326

[5] Ross, R., Dagnone, D., Jones, P., Smith, H., Paddags, A., Hudson, R., Janssen, I. 2000. Reduction in Obesity and Related Comorbid Conditions after Diet-Induced Weight Loss or Exercise-Induced Weight Loss in Men: A Randomized, Controlled Trial. Annals of Internal Medicine 133(2): 92-103

[6] Kluitenberg, B., Middelkoop, MV., Diercks, R., and Van Der Worp, H. 2015. What are the Differences in Injury Proportions Between Different Populations of Runners? A Systematic Review and Meta-Analysis. Sports Medicine, [e-journal] Vol. 45, Issue 8, pp. 1143-6

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