Blue/orange XSS separation makes no sense to me

I think we can agree on the fact that XSS is used to calculate training volume/intensity and is also used to determine our state of fatigue. I just played around in the workout planner and there is something that doesn’t make sense to me, in that regard:

2 examples:
I make a 1 hour training block at my FTP (well technically 59 minutes) :

98.3 XSS low intensity XSS, all others zero

Next I make a 1.5h training block at 70% of my FTP:

98.4 XSS low intensity XSS, all others zero

So for the algorithms used here, there is zero difference between doing the first or the second workout, while I presume everyone knows that the first is a very hard workout leaving your legs in a seriously fatigued state, while the second one is a workout one can do 7 days in a row without feeling tired.

What am I missing here? I think the first workout should add XSS to the High Intensity XSS values. It doesn’t make sense this only starts happening from FTP + 1 watt, and not when we’re already at 90% of FTP.

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There are several topics discussing what you describe. Here’s one –
100% TP for more than an hour in workout creator? - General - Xert Community Forum

TL:DR – I wouldn’t worry too much about the gap in the model below TP. :smiley: Xert is aware plus you are never going to train that way. While you might include SS blocks for “harder” endurance training the majority of users opt for recommended LTP/Z2 level strain on LIT days.
Including Tempo/SS in endurance level workouts boosts XSS per hour and the Difficulty Rating (Score). You can see this visually in Workout Designer.
For example, compare these three 2-hour endurance level workouts (no MPA draw down).

88 XSS, Easy 1-diamond Difficulty (43) –

107 XSS, Moderate 2-diamond Difficulty (55) –

145 XSS, Difficult 3-diamond Difficulty (75) –

On my LIT days I’m picking blue/aqua (~LTP) most of the time (not green tempo/SS). YMMV

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It’s not about “am I going to train that way”. It’s more about Xert correctly recognising the state of fatigue. I have no idea how it works internally but I hope it accumulates more fatigue in the calculations the closer you get to FTP power output. It would make sense that this is communicated to the user somehow when they are doing their effort. It makes no sense that there is zero middle bucket being filled while riding at 95% of your FTP. I think the middle bucket should be wider.

I think @xertedbrain mentioned they experimented with this as part of Xert 2.0. But they were currently not sure if it made a real/tangible difference to the athlete.

The middle bucket is power > TP by definition. High TL is built with strain above TP, by definition.

To accumulate it differently, requires a wholesale change to how “high XSS” is calculated and how HIE is used.

Materially, I don’t know if there is going to be a noticeable difference if we make a change of this sort, having looked at many thousands of profiles over the years. TSS is just one dimensional, deeply flawed but yet still has many athletes using it, oblivious to its failings.

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