Problem with the decay algorithm


Is there something to do so that the decay method matches more closely to the real power I can produce ?

The thing is that, whenever I add workouts to the Planner page (I usually fill one week of workouts), if I go on the Progression page, I see that the estimated TP value increases by a couple of watts for that coming week. But, once the week has ended and I have finished all the planned workouts, the curve of my TP keeps going down. The only way to reset it, is to do an all-out workout and get breakthroughs. Which usually gives me about the same numbers I had previously.
What is disturbing is that, if I don’t go for a BT, the decay algorithm gives me numbers that are too low for me to progress anymore. What I mean is that, for ex., with my last BT in August, my TP reached about 290-295W. Since then, I kept training, but Xert now estimates that my TP is around 267W; and the problem is that XATA now suggests me workouts with targets that are, potentially, 25-30W below what my previous BT was. So I’m doing workouts that are much easier than what I was doing just after my BT. The difficulty of the workouts goes down, and down, and down, until you go (and succeed) for a BT.
So, I keep training, but week after week, the workouts become easier, and that’s not because my fitness is improving, but because Xert suggests lower targets for my workouts.

What to do about it ?

Set the decay setting to ‘No Decay’ and then the predictions will increase if you increase your training load.

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Yes and after changing it, if you want you can go back to your last breakthrough and lock it, forcing a recalc with ‘no decay’ from that point as well. Also fixes the training loads etc. for that period too

Can you explain that procedure in detail?

Been a while since I tried it but pretty sure you first update decay settings in your account settings, then open the breakthrough activity, go to advanced MPA then click save.

The articles say ‘save / lock’ but the button just says ‘save’ now…

(There is also an option to ‘lock’ in the activities table, but in my experience that does not work… at least didn’t last time I tried)

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Thanks, I did it.

Now, as my last BT is 2 months old and Xert suggested me easier workouts since then, I guess that I need to do a new BT attempt so that the new workouts will be achievable ! It’s been several weeks that I’ve been training with 5W, then 10W…15W…20W below that BT, I’m pretty sure that in the next days, the suggested workouts may be too much intense ! I will probably have to decrease the targets by around 20W at first and progressively increase them week after week… Moreover, I’m now back on the HT for the next Winter 5-6 months, and I know that I can’t push indoors the power that I was able to push outdoors !

PS: I set the Decay to “No decay”, but I see on the Progression Chart that it’s still moving my TP up and down since that BT. Really, I think that that curve looks much better and more logical than the one from the Optimal Decay (though I think that I lost a couple of watts since I trained on a lower load by following XATA).

Question: how does the “No Decay” parameter calculate the TP ? Isn’t it supposed not to change the TP (at least, downward) ? (but really, I prefer the way it’s currently looking on the graph: slowly going down when I miss a couple of days of training, but slowly going up when I follow the plan).

No decay means no decay relative to training load… so it moves with changes in training load but nothing else. Full description says ‘no decay, training load matched’ from memory

I would just try with the ‘new’ signature and see what happens :stuck_out_tongue_winking_eye: but a BT is not a bad idea going into winter

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As other have mentioned if you aren’t regularly generating BT events during your rides/workouts you can use the “No Decay – Training Load Matched” setting. See full description here –

The other option is leave the default decay setting at optimal but select your favorite BT workout from the library whenever XATA warns you 3 weeks have elapsed since last BT.
You must manually select a BT workout as one won’t display on the recommend list.
It only takes about 10 minutes of effort to generate a signature validation check using this BT workout – Xert - Login

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