HIIT: Our Ancestral Fight or Flight Response?

HIIT – The Missing Evolutionary Link in Your Training?


These days, you can’t go anywhere near a gym without someone asking if you do ‘HIIT’? It sounds like one of these dodgy ‘legal highs’ and I suppose to some extent it is.

High Intensity Interval Training is currently touted as the biggest breakthrough in fitness training in the last 100,000 years. A big claim indeed, but since humans stopped running away from big scary animals and chasing after other poor defenseless ones, a large hole has been left in both our physical, psychological and physiological needs.

And the facts do seem to bear it out; indeed Michael Mosely was commissioned to produce a whole documentary for Horizon and the BBC about thrashing oneself to within an inch our physical limits for a very limited period of time. Today, every fitness website’s got its own idea of what HIIT actually means, generally twisting, contorting and adulterating a simple idea to suit their own purpose.


HITT is suddenly everywhere, it’s like a rash, and if you didn’t know better you’d have thought it had only just been discovered…


What that nice Mr Mosely might not know – or at least hasn’t publically acknowledged – is that this type of short burst training has a fine evolutionary pedigree and in fact dates back to the dawn of humanity. Moving our bodies in this short and explosive way has a solid basis in the lives we once had no choice but to lead. Back when every living person was a hunter-gatherer and depended on their body, wits and energy resources to both flee from predators and catch its prey, HIIT came as naturally as drinking water.

100,000 years ago they certainly didn’t call it HIIT, of course. I’m pretty sure they didn’t call it anything in particular, other than “RRUUNNNN!!!” However it was badged, it was an inevitable feature of life and death situations and ignites one of the most basic of human reactions; an experience we’ve all heard about and many have inadvertently experienced…


The thrilling and intense ‘Fight or Flight response’.


So let’s strip away all the superfluous non-sense and get back to bare bones of what HIIT really is. In a nutshell, HIIT is simply simulating the human body’s natural response to an imminent threat, and nothing more fancy than working very, very hard (at your own personal physical limit) for extremely brief periods of time.

 Author Oliver Selway first became aware of HITT’s capacity for improving physical capacity 15 years ago when faced with his own life-or-death, fight-or-flight moment in the African bush.


Olly explains: In my 20s I spent time in the Sabi Sands nature reserve of South Africa with Pretoria University’s Botany department learning the skills necessary to become a game ranger.

Almost all of our daily excursions into the bush were at a low pace, walking through at a speed at which breathing was unaffected and conversation was easy – until one day we came face to face with ‘The Buffalo’

Having been previously briefed on the seriousness of such a situation and what to do, my heart was hammering away in my chest and ears. Although every fibre of my being screamed “RRUUUN!” and we could actually smell the angry buffalo just metres away, no-one panicked as we backed away. Once out of immediate sight of the buffalo, we took off like scolded cats to put some distance between them and us.

I didn’t know I could move that fast as we furiously put distance between us and the buffalo with more pace and sheer energy than I had ever before experienced – fuelled by the genuine danger and powerful thrill of the encounter.

Looking back on it, it probably wasn’t textbook stuff – but because we had escaped a situation which we knew was potentially lethal (and had been the end of many unwary African natives and quite a few tourists), I felt unbelievably exhilarated.

 I have never before, nor since, felt so totally alive!

For the next few days I was absolutely buzzing. The grass was greener, the sky was bluer and the bush was, er, bushier. This wasn’t just some weird personal psychological aberration though: the whole group I was with felt like this. Each and every step we took outside the safe confines of camp was laced with consequence – a new, very real potential for danger: We were living on an exhilarating, natural high.

It seemed like my limbs had discovered yet another gear. Whenever I could find an excuse I would break into a sprint just for the hell of it. I wanted another hit of that energy and euphoria – another stab at that hidden ‘turbo boost’ button I just couldn’t get enough of.

The whole world goes into slow motion: suddenly heavy things seem light and limbs take on a powerful life of their own. This is the delightful ‘fight or flight response!

 Now you know where HIIT has its origins, you’ll understand why experts advocating 20 or 30 minutes of HIIT don’t know what they’re talking about. The sort of intensity that is demanded for HIIT cannot be kept up for me than 20 seconds or so. And it can only be repeated a limited number of times before total exhaustion sets in.

Instead, revel in the brevity of such an approach; go flat out from the outset; keep nothing in the tank. Train like this a few times a week and you’ll soon have a level of fitness that surpasses anything your steady laps of the park will ever allow.