There was an odd thing happening in the Equinox Gym, the newly opened temple of fitness that occupies part of what was once the Biba building on Kensington High Street.
Alongside the honed and toned hard bodies pounding the exercise machines, in among the glistening biceps lifting weights only marginally less substantial than a new Routemaster bus, a sudden reversal of evolution appeared to be taking place. The several million years it took for man to walk on two feet had, in less than an hour, been wiped out. After no more than 45 minutes in the place, I was no longer capable of standing upright and was reduced to crawling about on my hands and knees.
That is what happens when you engage with the latest fitness craze to arrive here from the United States: you feel it to the point where you end up barely able to stand. But the temporary return to primitive perambulation is worth it, or so its advocates insist. The rewards are substantial.
I had arrived for my appointment in the gym after a moment of confusion. The Telegraph’s commissioning editor had rung me to say she was looking for a reporter of a certain age to try out HIIT. I knew I was getting on a bit, but I had no idea I was quite so obviously showing the need for a course of oestrogen injections.
“No, not HRT,” she said. “HIIT: High Intensity Interval Training. It’s the latest thing from America.”
In New York, they have gone mad for it, she told me. In gyms across the city, thousands are weekly engaging with the system, swearing by its benefits. It is predicted it will be the big thing in Britain this New Year, forming the basis of many a January keep-fit campaign.
You can understand why HIIT would so appeal to the New Yorker. It promises not only results but speed of delivery. The system’s advocates insist that it enables you to get fit and shed the pounds in less time than conventional fitness regimes. What would take hours on complex machines and in clanking weight rooms can be achieved in minutes. For the time-poor city dweller, this is manna from the fitness gods.
And the science is conclusive: if you want to lose weight or get in shape quickly, this is the most effective way to do it. A study by the University of Western Ontario found that if you spend half an hour walking, you will burn off 100 calories, 85 of which will come from your fat stores. Go for a jog and in the same time you will burn off 200 calories, 100 coming from fat deposits. Use that same half-hour doing HIIT, however, and more than 500 calories will be burned off, 150 of which will be from fat.
That is only part of the story, however. The study also found that, because of the substantial increase in resting metabolic rate caused by an HIIT session, the body can continue to consume fat for up to 24 hours after you have stopped. It is called excess post-exercise oxygen consumption. In other words, because HIIT kickstarts the body’s innate repair system, you slim down even as you recover. The thing works even when you aren’t. Now that is a proposition.
The BBC presenter Michael Mosley demonstrated the effectiveness of high intensity work-outs on a Horizon programme in 2012. Under the instruction of Jamie Timmons of Loughborough University’s sports science department, he was put on an exercise bike and made to pedal at his fastest possible rate for just a minute at a time. A total of as little as three minutes intensive training a week had a surprisingly beneficial effect on Mosley, as much on his wellbeing as his weight.
But while it might not take long, nobody should be under any illusion that HIIT is an easy short cut. It may be over in less time than I was held at a red signal at Edgware Road underground station en route to the gym, but, boy, do you work for it.