I have a question: Two weeks ago, during my “return to training,” I did 3 FTP tests over a week and a half (I was worried there might be an issue with my smart trainer).
The first test was with my road bike (with its power meter) via the Xert app.
The second was with Zwift and my smart trainer.
The third was with the Xert app and my smart trainer.
This way, I covered all the possibilities and reassured myself (I’ve only been training seriously for a year). Spoiler: there were no issues with the smart trainer—195W on the first test, 200W on the second, and 197W on the third. Up until then, everything was going well; I was happy with my progress and ready to start a new training cycle with confidence!
However, this Sunday during a ride with a friend, where we really pushed hard on the climbs, Xert gave me a breakthrough and updated my FTP to 227W.
The jump seems huge, and honestly, a bit odd considering I finished my FTP tests feeling like I was near death .
Do you have any ideas? Does this seem possible to you? For now, I’ve flagged the activity.
Post your BT report from that activity. View activity details and click the BT badge icon next to title.
When you say FTP tests are you referring to a Fitness Test workout from the Xert library ridden in Slope mode or a traditional FTP RAMP or 20-minute test?
It is not usual to bump your signature during a hard group ride or any activity that pushes you beyond your predicted MPA point during a max effort. However, if that point includes a sharp rise followed by an immediate drop (you stopped pedaling) the bump you describe may occur which does warrant being flagged.
I’ve had similar issues with my TP being raised too high after a breakthrough, most recent example was Xert rised my TP to over 280 when during a 20 min power test I could only hold 270 and like yourself, that was my absolute limit (sadly).
I find it frustrating as it then means I don’t trust the numbers or system, despite desperately wanting to, having spent a good number of years as a time trailist, I have a reasonable sense of where my threshold is, I’ve tried over the years using Xert multiple times with different acounts and at some point the inflated TP curse seems to strike. I’ve compared my Xert TP to both Intervals.icu and WKO5 and each time my Xert TP is the highest (sometimes by quite an amount).
Have you spent time to investigate those BT events to determine if there’s a pattern?
I believe a segment of Xert users train a certain way or with a particular goal in mind (TTs?) that doesn’t factor in the spectrum of how max efforts affect signature calculation.
An FTP estimate based on MMP sampling doesn’t equate to how TP is derived through MPA analysis.
While the two values may be close for many users, they won’t be the case for everyone.
My acid test is whether I can train effectively with the numbers. That is easily determined by riding over/under intervals centered on TP and LTP and judge the results by RPE.
If the bump isn’t warranted, I’d flag the entry.
Regardless of how FTP and TP are derived, both are calculated values subject to bell curve distribution. IOW they are a proxy. If close enough to train by you are all set. If not Xert provides the tools to adjust either by flagging an activity or manual adjustment (edit the activity signature and lock/save). That may sound counterintuitive (shouldn’t I rely on the algorithm?) until you recognize the scope of bell curve distribution, and the fact FTP isn’t and never was your “one hour” power.
Yes, I’ve tried in the past to train with the numbers, but quite often it resulted in failing workouts. The last time I got a breakthrough and my TP went up, I just knew that there was no way I could use the numbers given to me. I’ve since done several workouts , which has just confirmed my feeling. I fully understand that FTP is not purely 60 minute power, rather a range, usually between 40-70 minutes steady state effort (maybe a little less, maybe a little more in some people) and I get that TP in Xert is slightly different (the point at which you draw down MPA) , but there would be no way I could’ve held the TP given to me after a breakthrough for anything more than 10-15 mins (and that’s probably optimistic).
I really wish there was a standard test to get at least a base signature, I know this goes against the Xert way of not doing FTP tests, but I like to see if I’m progressing after a certain amount of training, by always getting breakthroughs in different ways, I never know if it’s because it was on a climb or was it the on/off efforts or such like that contribute to the figures produced. I think it would be good, particularly for new users, to have a set of workouts that you could do to generate/check your signature. I have WKO5 from my racing days, and find that populating the PD curve gives me a fairly accurate FTP figure, which I then often check by testing it.
Great effort @KeroZen ! Thought I would chime in here as well…
You can use the ‘Previous’ button to view the MPA analysis with the previous signature. What I take away from this analysis is that your Threshold Power has got to be higher than ~200 W, or your MPA would not have recovered enough for you to sprint 30 min later with as much power as you did. Notice how your sprint near the end of this segment is dramatically higher than the calculated MPA - by definition, this shouldn’t be possible - that’s why Xert ended up making an adjustment to your Threshold power, not because you had a 20 min max power effort. Hope this helps clarify things a bit!
But how do you explain that during a classic FTP test, I am unable to push harder than what I did two weeks ago? It’s a bit counterintuitive, isn’t it? I swear I did my best
.
Thought I would chime in here as well…
