Interval Four Had Other Ideas

I use TrainerRoad, a lot. Winter and summer. It's just easier than the alternative, which in Scotland mostly means trying to work out if three layers is enough or if you need four, and whether it's actually going to rain or just look like it is going to rain. The turbo removes all of that. I turn up, I ride, I don't need to check anything. The weather outside can do whatever it likes.

There is also something to be said for the structure. TrainerRoad tells you exactly what to do and for how long. There is no improvising a route, no deciding mid-ride to cut it short because the hills were harder than expected. The session is the session. You either do it or you don't.

Outside this morning it was 4°C and overcast, a 15 km/h south-easterly doing its best to be unpleasant. I noticed this from the window before heading on to the turbo.

Thatcher

Today's session was Thatcher, which is eight two-minute intervals at around 115% of threshold power, with 90 seconds recovery between each. I did something almost identical last week and got through it without much drama. On paper today was the same thing.

It was not the same thing.

I suspected something was off from the first interval. My legs were not interested. The cadence was the tell. I normally sit in the mid to high eighties during these efforts. The first interval was about right. After that it dropped steadily, hitting the mid-sixties by the middle of the session. The last two intervals I managed to claw a bit of it back, but not enough to feel good about it.

Intervals one, two and three went in. Not well, but in. Then came interval four.

I stopped. Not a scheduled break, not a planned recovery, just a full stop. The legs had simply stopped cooperating and I had, reluctantly, agreed with them. I sat on the bike for a bit, breathing, staring at the TV, wondering if Saturday's parkrun was to blame. That 5k was faster than usual. Whether that was the cause or just a convenient excuse I genuinely can't say. Probably a bit of both. Fatigue doesn't always give you a warning. Sometimes it just turns up.

The break was a few minutes. Long enough to feel like I was admitting something, short enough that getting back to it still felt possible. The question with stopping mid-session is always whether you're going to actually restart or whether you're going to find a reason not to. I restarted.

The rest did help. I got back to it and finished the remaining four intervals. There was nothing elegant about it, just turning the pedals until the session ended. The power numbers held up across all eight, which is the only decent thing I can report. The legs could manage the wattage, just apparently not the cadence to go with it.

The Ronde Van Vlaanderen Problem

I should mention that while all of this was happening, I was watching the Tour of Flanders on catchup. This is my favourite race of the year and I will arrange everything around it, or at least arrange to watch it the following morning while suffering on the turbo. It was on the TV, in the background, providing a steady reminder of what real suffering on a bike looks like.

The professionals were riding up the Koppenberg, the Paterberg and the Oude Kwaremont, which are short cobbled climbs that look manageable until you realise the gradients and the race pace and the 200km already in their legs. I was on the turbo, struggling at 115% of my threshold, and still finding it harder than I should have. I did not find this comparison motivating. If I had been out on those cobbled climbs in Belgium at the pace I was managing today, I would still be somewhere on the Koppenberg right now, almost 24 hours after the race finished. Probably pushing. Actually, definitely pushing.

The Numbers

47:54. 22.88km of virtual road to nowhere. The power data tells the story more honestly than I have.

The gap between normalised power (182W) and average power (156W) is what you'd expect from intervals — big efforts, short rests, nothing in between. The intensity factor of 0.91 means this was a genuinely demanding session, even accounting for the unscheduled intermission. The cadence average of 73rpm is not the 83-87 I would normally aim for. That gap is the whole story in a single number.

Heart rate stayed controlled throughout, which at least suggests the cardiovascular system was willing even when the legs were not. Max of 145 bpm is comfortable ceiling, nothing alarming. The legs were the limiting factor, not the engine.

The eight intervals got done. Six of them properly, two of them on borrowed determination. The turbo doesn't care either way. It just records what happened.

All indoor sessions recorded on turbo trainer via TrainerRoad. The kilometres are virtual. The difficulty is not.