This. You want pick workout alternates by looking at the IF, TSS for workouts also labelled in the same category. Something different but similar TSS, great probably same difficulty. Higher IF but still threshold, great you have found something harder.
Isn’t this what you get from comparing your power duration curve for Time Period A vs. B?
I don’t see any problems with the Progression Levels falling when they’re being measured against different targets. What else would you expect? Like, doh.
It’s very easy to create something that doesn’t have much meaning and looks like a metric worth pursuing. I wouldn’t want that.
I’m sure there’s a good solution somewhere. Current PLs are good as a shorthand for measuring relative progression in zones, but the gap is comparing over time or against other riders.
Cross posting from another thread.
I personally don’t think the current PL’s are broken at all, and I’ve never had an issue with them. That’s with the trainer indoors, lots of outdoors, and lots of custom workouts. It’s really really rare (e.g. Custom Sprint or Anaerobic Workout) that you get the PL system confused. At least for me anyways.
And, I don’t think there’s any issue at all comparing over time or against other riders. That’s what TSS, CTL, IF, PDC, and W/Kg help you do. All are well defined and understood, and standard metrics. I’m routinely using these to compare efforts and seasons even when FTP was different.
I think there are enough challenges with switching to an absolute number that it’d probably be worse. You need some fixed unit of measure - e.g. Watts, KJ’s, and have to have a way of specifically saying here’s how it’d work. I think they might actually end up being harder to understand, more confusing, and a step back.
I’m open to being proven wrong, but I’d actually like someone to lay out a clear recommendation of how it could work, what units of measure, and how that’s actually “Better” as opposed to just general dislike of the current system.