2x20s, HR vs PE

SCR Pedro

Hey guys. I'm continuing with my training plan from my previous thread. That means a longer ride at the weekend, a tempo ride during the week, and also a 2x20 session on a gym spin bike.
I'm no newbie to intervals. I used to be able to do them on the turbo trainer, using cadence and speed, with a HRM, so it was a lot more controlled, and I could measure each performance against each other. Now I only have a HRM and PE. I get PE. I can do both intervals holding what I perceive to be the same effort, and the cardiac drift would roughly confirm the effort is constant.
Today, my HR was sky high (10bpm) higher, for what was a PE effort typical of 2x20 intervals. Numbers for reference:

Today
First 20: 176BPM (exactly 90% Max HR) (Max HR (196) field tested recently on a 15% gradient sprint)
Second 20: 180BPM

Previous efforts are usually no more than 90%. Last week saw me complete both at 165 & 170 BPM respectively. So a lot lower, but as much as PE would let me do to finish both intervals just-and-no-more.

Question: was I right to work at such a high HR, when PE let me complete both intervals? Should I have backed off, and paid more attention to my HR than PE?

Somebody is bound to ask about goals. They are eventually fast club rides, lighting it up on the climbs, and generally going faster over longer distances. Perhaps even racing, if I get fast enough. There is also zero chance of working with a power meter. I wish I could, but it's not going to happen. I am also sure people will suggest I am over thinking this, but I like analysis.

Cheers 8)

imposter2.0

2x20s are much like any other interval - the aim being to ride the interval at the highest possible effort level which you can sustain for the interval's duration. Ultimately, that's going to mean PE, not an HR number - or even power number. As long as you are more or less doing that, you won't go far wrong...

SCR Pedro

So pretty much what I did this evening? If that is the case, then is there any point in using a HRM during intervals? Can it actually mean anything that there is such a difference between the last two sessions? For what it's worth, I had an espresso half an hour before this evening's session. But would that actually cause the HR to go higher for less effort?

Cheers

imposter2.0

Setting your HRM to read as a % of MHR rather than an actual number (ie 176) makes a lot more sense, if you haven't already done so. Using HR is useful for lower level intervals like 2x20, as it serves as a guide to approximate effort - but that's all it is. At the end of the day, if your HRM is reading under your target number, but your RPE is telling you that you can't go any harder, then you have to listen to RPE. The next day might be different.

SCR Pedro

Makes sense. Thanks!