Hi all. I’m hoping you can help a relative Xert newbie.
I used Xert through the summer and into my race season, which is in the form of hill climbing (in the UK). These involve savage, horrible efforts ranging between 2 and 5 minutes. If I’m being honest, I found that Xert did a great job in the Build and Base phase, but in the final 3-4 weeks when I needed to focus on top-end, I kept being served z2 workouts and somewhat lost trust, so went back to a tried and tested training plan which has worked for me in previous years and did the job this time as well. I’m sure its likely user error, however from that point I started to somewhat ignore Xert workouts for the remainder of the 2023 season.
I did however get breakthrough after breakthrough on my races. Which was great, but I then found that my threshold power (and yes, I know this isn’t FTP, but I was checking the hour power on my curve as well) was laughably high - in the 360s at one point. Which, as a guy who at the time weighed 60kg, had me being at a theoretical level not too far off the world tour. Which, I am keenly aware, I am not.
I then took some time out and paused my Xert sub. However I’m back on it now, but my Threshold power is still ridiculous for me - it’s currently 348 watts, and I’d struggle to now do that for more than 8-9 minutes (if even that). I’ve tried a few things to reduce the TP, including manual settings changes and fiddling with decay, as well as flagging a spin class that led to a similar breakthrough 3 weeks ago (different PM, so easy to ignore that) - but all of these either do nothing, or lead to an even higher power.
So how else can I reduce the TP? Otherwise, I can stick with my current solution (just reducing every workout’s intensity to c. 90%, which is more in line with what I roughly think my FTP is and in terms of RPE feels right for the respective workouts) for now, but long term I could do with a little more accuracy in my benchmark power.
Thanks Hans - Re PMs, I don’t use the same ones (wattbike indoors, assiomas outdoors), but the RPE between them is very, very similar, and I’ve used them both for 3+ years now and have trained with power for about 6 years, so have a decent idea of what it feels like - appreciate there might be a few % difference, but not 10+% - and besides, I couldn’t hold that power indoors or out.
Screenshot of the last breakthrough is above. It makes me feel ill just looking at it . Historically because my racing has tended to focus towards ‘one rep max’ 2-4 minute efforts I’m sure that might distort things somewhat, but prior to this some all-out training efforts had left me with a TP of around 320 which felt punchy, but not too far out where I was at that moment.
Please also find the breakthroughs below (different posts sorry due to being a new member, I can only share one image at a time). Slight memory fail on my part - the last breakthrough was fairly modest, I’ll also share the one with the much bigger jump a few weeks before.
I’d be curious what @ManofSteele would say here. I’m assuming you feel like the model faily well represents your shorter efforts, so on the face of it, it looks like somehow it’s got a combination of you PP and/or HIE really wrong. If your PP was higher, and your HIE was around 25, I’d think your TP could be substantially lower to accomodate that breakthrough.
That would be normal if form calc indicated yellow/tired for days.
Did you try adjusting Freshness Feedback to increase intensity whenever you felt ready for more?
If you recover quickly from HIIT you can adjust the new Recovery Demands slider to the left.
By “manual settings changes” do you mean editing last BT signature followed by Save/Lock?
Are nearly all of your BTs on hyper-short race efforts?
Xert works best when you’re able to fatigue naturally instead of various tests which feature “unnatural” fatigue. We call it unnatural since there are hardly any instances in normal riding where you increase your power output minute by minute until you can’t. The other type of unnatural fatigue is during an 8 min or 20 minute test, where you push yourself until the testing period is over, where most athletes will typically immediately stop pedaling. The abrupt stop does not permit Xert’s extraction algorithm look at the way you fatigue. Instead, Xert is looking to see natural fatigue in your power data, which typically manifests in your power slowly diminishing as MPA decreases and continues to limit your ability to produce power. Thus, with Xert, the last minute or two of the fitness tests – when you’re under the most fatigue – tells more about your fitness than the rest of the test.
As its probably a bit of a PITA to screw pedals on & off the indoor bike, I could put them on once and record some minutes at different watts to then compare the two resulting .fit files with a tool like https://compare-the-watts.com/.
If your a lucky, both PMs match close enough and you wouldn’t need to bother. If not, you might rather want to follow Hans’ advice.
Apart fromt that, I doubt the issue is the type of “test”. After all, he’s very likely not stopping to push past his power meets the MPA curve. He is trying to win a race. There should be nothing artificial about that.
I experienced a similar issue (way to high TP after BT) a while back. I commented to Scott that my PP had decayed too low in my sig and I didn’t made the effort to reset it. I assumed it would not be that important, as I don’t care much for short PP-like efforts.
As Scott suspected that this might explain my too high TP, I reset my PP one day later to my actual capability (just by mixing a short max sprint into my ride). Then I flagged the recent BT effort which gave me the too high TP, changed it’s data via fitfiletools and uploaded it again. This time the resulting TP was spot on compared to my own estimation via RPE.
So in short: Is your PP set correctly? If not, you might wat to fix that.
After, I am sure support could lower your sig manually enough so you could get a new BT to reset yout TP/HIE.
Have you tried playing around with the HIE and PP on this same breakthrough effort, so see what those two would need to be with a TP of 317? I’m not suggesting that you then make that change, I just wonder what that would look like. As has already been said in this thread, an HIE of 13.2 doesn’t seem right for a PP of 947. I think I had the opposite problem last season, and I’m not sure where the fault was introduced. Basically I had an HIE that hovered around 30, so that meant my TP stayed low. It still modeled the right BT point, but TP was probably too low. That, or all the previous years I’d used Xert, my TP as too high, and HIE too low. I suspect the truth was maybe somewhere in the middle.
I don’t like manually changing my signature, because then it feels like I’m just introducing even more error. I’d try a BT effort where you’re not stopping at a finish line, or a timer. Make sure the part of the effort at the end has plenty of ‘runway’ to keep going after you’ll likely be bottomed out on MPA.
This sounds the cause of the problem to me, honestly didn’t realise that, but does make a lot of sense. I assume this is best solved by flagging up my last few BT efforts? @Beutelfuchs I’ll also try resetting my PP as well.
@hpbieker totally appreciate your help but I don’t think I’ve explained myself well enough; my RPE is almost identical on the same power levels both indoors and out. It’s been a little while but I’ve had to dual record for Zwift before and the watts were within 1% at the time, and I haven’t noticed any drift. Indeed, these issues started while the Wattbike was gathering dust in the corner of the garage, I have the same troubles outdoors.
It all sounds like I need to do a little more reading and troubleshooting, thanks everyone for your help and advice, really appreciate it!
Actually my Wahoo Kickr Bike reads 10-12 W higher than my pedals. If it was due to the drive train loss it would be the other way around.
10-12 W might not sound that much, but it most likely means that you will only be able to the breakthroughs with the power meter with the highest numbers. It means more for the longer intervals of course.
I’m assuming this activity was before we rolled out changes to the signature extraction algorithm. I was also thinking HIE was a tad low. If re-uploading this file, I suspect the new algorithm would potentially adjust HIE up a bit more to bring it more in-line with the user’s Peak Power.
If PP is significantly underestimated (and by extension HIE as well), it could result in TP being a bit overestimated. Overall though, the new extraction algorithm should generally do a much better job at adjusting the user’s HIE to bring it in line with where we’d expect HIE to be given their Peak Power, which also means that the TP estimations should be improved as well