Rather than describe a four-minute exercise regime devised by a possibly sadistic Japanese professor, I will reproduce here every word spoken as Robert Scrivener, my trainer, leads me through it.
The scene is a gym studio with a wooden floor and a mirrored wall. I have not included any grunts or cries (all mine). The only words that are mine are the swear words:
"Arms up, down, good, get height. Big push, down, up. Let's go. Big push. Come on, all the way through, and again.
"Crawl it out, quickly. Up, come on. Let's go. Jump, turn, use your arms. Come on, Si. Let's go. Back, knee low, chest up. Keep going, swing your arms."
"Jump to me, lift the leg. In, jump, this way. Come on, Si, come on. Big jump.
"Get some height. Arms up. Let's go. Drive.
"Let's go, in out, quick. It's got to be fast, got to be fast. Let's do this. Chest low. Come on, come on. One more, one more, let's do it.
Knee low, come on, come on. Make it count."
"Jump. Last 10, big push, big push. Come on. Let's do it. Last one. And the jump. That's it."
My face is red, I am sweating profusely, my heart is threatening to burst through my ribs like John Hurt's alien on steroids and, although my workout has lasted precisely four minutes, I'm done for the day.
I have completed the Tabata Protocol, a little-known fitness regime that is as brief as it is brutal.
Izumi Tabata, its inventor, is a Japanese professor and pioneer of sports science whose research in the mid-1990s showed that high-intensity exercise in 20-second bursts separated by 10-second rests achieves more in four minutes than an hour-long slog on an exercise bike.
The regime spread by word of mouth among athletes and fitness trainers and helped inspire the trend for high-intensity interval training.
Some gyms use Tabata's name but the man himself has now emerged from his laboratory at Ritsumeikan University in Kyoto to reclaim his brainchild. Aged 56, he's signed his first licensing deal to launch Tabata classes and, later, fitness DVDs for those without even the time to leave their sitting rooms.
Scrivener has been creating the official Tabata routines as part of the deal with Universal Pictures, the film and distribution giant. I'm already a bit breathless after our five-minute warm-up at his north London gym, and even more so when we go through the four exercises.
The first and simplest, a side-to-side Sargent jump, involves springing from a squat like a frog while reaching up with the hands and, moving sideways through the air, landing in another squat. Repeat for 20 seconds, as hard as you can.
According to the Tabata principle, any high-intensity movement will achieve the desired effect. The key is to get the heart pumping and tip over from aerobic into anaerobic exercise. Or, as Scrivener puts it, "as long as you're going balls-out, that's the main thing".
Put simply, anaerobic metabolism is triggered by high-intensity exercise, when muscles require more fuel than breathing can provide. It's the sort of exercise that hurts and is tough to achieve while jogging, say, or cycling. It's also important for those who want to be truly fit.
In the 1980s, Tabata was part of the team of scientists that developed a way to measure anaerobic metabolism, back when interval training involved sprints to the theatre bar. It allowed him to compare different ways of working out, from "balls-out" down the pain scale.
In his breakthrough study, Tabata put a group of students on exercise bikes, ordering them to pedal like maniacs in 20-second bursts broken up by 10-second breaks, for five days a week. A separate group pedalled at normal levels of exertion for an hour a day over the same period. After six weeks, the maniacs had boosted their aerobic fitness by 14 per cent, compared to 10 per cent in the second group, the members of which had worked out for way longer.
Tabata applied his techniques as a coach with the Japanese Olympic speed-skating team and never imagined it would have appeal below elite sport.
"I didn't expect ordinary people to want to do it," he told me in London the week before my routine with Scrivener. "I was a little embarrassed because it's very demanding but if you look on YouTube you see many people enjoying it."
But as regimes and fitness classes inspired by Tabata's research have slowly grown in popularity, the professor says he believes gym-goers aren't being pushed enough. "If the intensity is lower than the one I approved it's less useful," he says.
Scrivener has got this message, as my buttock muscles in particular tell me as we warm down after four minutes of the toughest exercise I've ever done.
Yet, with stretches before and after, plus a few minutes to learn the drill, my visit to the gym has lasted little more than quarter of an hour, perfect for those who would exercise more if only they had the time.
It also allows me – and this is not part of the protocol – to eat two lunches when I get back to my office and not feel terrible.