I participated in 3Dapt study Jan-Apr 2026. Look forward to results!
Since May 2026, been doing mostly Low/ subthreshold trying to improve my aerobic fitness. (I’m far from a “diesel engine”)
After changing it up with some sprints and Vo2 workouts for 3 weeks, my signature changed significantly. (Kindly see chart below)
I understand that because my PP and HIE went up, now LTP down. (Xert calculation)
Is this physiologically sound? Will LTP be calculated the same in Xert 2.0?
Carbs /fat calculation is totally different now, workouts are different and I now suddenly don’t know what to trust? (LTP is 40w lower all of a sudden.
My physiology could not have changed suddenly, yet i know PP is correctly measured. i didnt sprint/ do VO2max work for months) so it was “falsely low”… I want to be more efficient “aerobically” but with a sprint/ intense workout my LTP will drop. Will my LTP ever go up? If i flag the workout, then the PP is inaccurate.
@xertedbrain@ManofSteele
If you were in my “saddle”…. what LTP will you use to train at? LTP 213w ? 173w? (40w difference).
Should i manually adjust Xert LTP based workouts now?
Im far from an expert in Xert, but I would tell you that the model is very raw. It’s a crude approximation. Basically, it would severely over index on the efforts that you are strong at. For instance, I just did a 3min max effort, and my threshold shot up 35w automatically, whereas the WKO5 model (which is the gold standard IMO), somehow adjusted slightly upward.
I do like other features of Xert, that’s why I’m still a paying subscriber. But you need to know your physiology to be able to use it. They completely oversell the idea that a good signature is calibrated with any hard effort.
Specifically on LTP, for me this level corresponds roughly to a sustainable tempo, something you should be able to do 3 or 4x 30 minutes when trained. It’s about 20-30w above my LT1. So It seems you have a high Peak Power and W’ and a relative low threshold and your 173w LTP is roughly the easy endurance zone. You can see how LTP means one thing for you (sprinter type) and a different thing for me (climber / GC / all rounder)
If the new signature better reflects your high intensity capabilities I guess the signature is ‘better’ however that also assumes you have some longer recent breakthroughs(?) which reflect a max effort eg 12 min plus. This is so Xert has some max data across the power curve, and it’s possible your long power has also increased. So, in your shoes I’d also do a long all out effort then see how it looks
Thanks for the replies. We’ll see how Xert 2.0 improves some parameters. I guess I will have to keep doing “long” all-out efforts every once-in-a-while to ensure that my signature is “up-do-date” and accurate with long-duration data.
You posted the “what” chart. Let’s see the “why” chart. (YTD XPMC)
Also post the BT report and power chart for the activity where the jumps occurred.
You can approximate your LT1 by riding a Lucy workout (o/u LTP) and judge how that feels by RPE (VT1). Adjust % intensity as necessary.
Or based on your Z2 rides what wattage do you naturally fall into when you stay below VT1?
Same story for me. I’m the same type of rider (high HIE and PP, low TP). Xert has always underestimated my LTP (measured via lactate testing at 213W), and I honestly don’t know how to align Xert’s metrics with real-world data. BTW, I did a 20-minute FTP test and it showed 280W (in intervals.icu) but Xert set 262 on that test.
I don’t think I’d trust a “relaxed ride” to dial in my signature.
I’d probably flag or edit that activity rather than accept the change to both PP and HIE.
If you zoom in on the five sprints how many secs long, how close in watts, and were you fully rested between?
IOW were they truly a series of max effort sprints to validate your PP?
Have you replicated the new PP since the adjustment?
As you surmised putting in a max effort of ~10+ minutes now and then is good practice to feed the model.
Or execute one of the standard fitness tests indoors in Slope mode – and see if TP is affected.
Based on your XPMC I suspect a latent TP bump is in the wings. If that’s the case your LTP will be higher.
The abrupt dips in TP back in mid-April and May seem odd.
Once you confirm you signature is dialed in you could join the 2.0 Beta to see how LTP differs in the updated model as a parameter rather than a modeling artifact.
Thanks for the reply. I was playing around, not racing. But they were 8-10sec sprints. (see below) I did not flag the activity because i haven’t done sprints for a while and there is nothing wrong with the data. So, I believe the PP data is accurate.
This was 3 days ago: Longer efforts to breakthrough. Gained ~6W TP… LTP still ~174w. I’ve accepted it. It will “correct” with time and other breakthroughs.
LTP is just a formula with scaling error:
LTP = TP - (HiE x 2.5). So if your HiE and TP is just slightly off, LTP is at least 2.5 times further off.
For practical reasons - no lab access: I use my real life 3h avg power from a best steady power ride (as few power spikes and power drops as possible) as a power ceiling in “low intensity”-Training. If my HR is below 130, I am happy. If it is above 140, it is no zone 2 for sure (maxHR 183).
My LTP over the season floated between 210W and 250W. 3h PB this season is 230W avg (including traffic light stops). I struggle to keep a steady outdoor LIT ride sub 150W because of traffic and uphills. I struggle to keep a steady LIT outdoor-ride far above 200W because of traffic and downhills. So if I settle somewhere between 150 and 210, I am fine with that. If my XSS does not fill fast enough, I will try to go longer for better adaption - not harder.
In xert, “low intensity” means everything below threshold power. It is allowed to go above LTP sometimes but not advised to do sweetspot every time “low intensity” is scheduled.
If your LTP was just 150W, you might also be struggling with staying below 150W because of traffic and uphills. For practical reasons I personally would try to set a max power ceiling at 199W (or TP whatever is lower) and try to stay between 100W and 150W whenever I can, but never stop pedaling. Pushing 199W over a bridge for 30 seconds is ok, pushing it for 5 minutes is not. Watch your HR. As you can extend your LIT-rides to 5 hours straight (just stopping for water refill), you will know what you can steadily do over this time without feeling too fatigued afterwards.
