“Functional training” is exercise that relates to how your body moves, rather than classic gym routines, which build up specific muscle groups. It typically involves non-gym equipment; stuff that you’d be more likely to find on a farm: giant tyres, random, heavy loads better suited to a dray horse. There are high-intensity bursts of effort, then shorter bursts to kid yourself that it’s getting easier. There is also a circuit element: the gym is broken up into stations, with a four-minute routine in each. Again, it’s a trick, breaking down time into frames that sound more than possible. Killer press-ups for 45 seconds? I could do that. There is an emphasis on using your bodyweight against yourself, which makes it the kind of workout you could do at home, although – trust me – you never would.

Most gyms offer this now, but I tried it at a new one (The Yard, in Canary Wharf, east London) designed specifically for torturing gymgoers. People in financial-services districts are so distinctive, I realised: so determined, so lacking in normal perspective, so peculiarly happy to get shouted at by an instructor. Maybe he didn’t shout at them; I was the only latecomer, flung immediately into 25 burpees and jumping jacks, a punishment for my lack of commitment.

On a logical level, I thought, this doesn’t function as punishment, since the thing everyone else is doing looks way harder. It didn’t even work as humiliation, because nobody watches anyone else at this intensity. Did it work as a show of authority? Hard to tell. It was extremely taxing. All emotions receded to the primitive: must do this thing; can’t remember why.

Much of the innovation is simply: that thing you do? Do it harder. The circuits with the bikes were measured in calories burned. Fifteen calories through cycling, then 15 via kettlebell exercises, then nine the next time, six the last. The thing about exercise bikes? You use hardly any calories. You’re better off not turning on the calorie counter, such is the demoralising effect of realising that, after an hour’s riding, you can have a whole extra rice cake.

The next station involved a TRX band and five clean jumps on to a box about 45cm high. I couldn’t do this. It wasn’t the effort – I just lost my nerve every time. Next was mat work, mainly very fast press-up variations on the Emom principle: this stands for “every minute on the minute”, but it means “do this very difficult thing for a minute”. It’s a staple of CrossFit, designed to motivate. There was an erg station, interspersed with sit-ups. You did each station twice, with a grand finale where the group was split into two to compete and high-achievers yelled at each other. It would have been anthropologically interesting if I had not using my entire mind to fight every instinct to lie down.

It was quite something. I know I went further than I normally would, because I ached for three days afterwards. At that point, I decided I’m too old for this racket

What I learned

The new gym thing is to wear a heart monitor throughout your workout and get your BPM projected up on the wall.