Sudden Drop in Threshold/LTP

Good morning!

I decided to do a BT workout last night because I wanted to “update” my signature. It’s the off-season for me and I’ve been doing much less riding with more lifting, running, and hunting/hiking. I’ve actually been on the downslope since late summer but that’s just from a peak training status for a 100 mile gravel race.

Anyhow, I was able to put out some wonderful sprint watts and sucessfully complete the 4 threshold+ intervals of the “Xert Fitness Test for Breakthrough.” My peak power went +622 watts (1687), my HIE +13.7 kJ (38.7), but my TP -20.3 watts (192). My LTP is now 95 watts, which is comically low (for an experienced rider) and something I’d do as a huge recovery interval for 360-400 watt efforts, not endurance mileage. It’s been hovering at 150-160 watts, from a season best of ~175, so that’s a HUGE drop.

My goal is set to Off-Season improvement and I’m on a Target Date plan for the first gravel race of the season here in mid-May. I’m not looking to ride more, even if it’s easier, as I take my off-season to mean exactly that–a period to recover my my mind/body and enjoy other activities. I still want to ride ~3x a week but not for more than an hour or a 50-miler outdoor cold weather group ride. I know that if I’m riding at 90-100 watts, I might as well be going for a walk with the dogs.

What gives and is there any way that I can fix this?

Flag that activity to remove signature calculation but retain XSS value.
Post your BT workout report if you want but I suspect you had a power spike.
Off-Season is a negative ramp rate so no reason to create a forecast or TED yet.

Got it. I’d like to keep the peak power though because it is accurate from the two all-in slope efforts.

Further thoughts? Thanks ridge.

Did you perform the entire workout in slope mode or only the prescribed sprint intervals that switch to slope mode?
If the latter, go to activity details, select Previous button at bottom and zoom in on the BT portion.
Did you actually reach a failure point during that interval or did the interval end before failure?
Ideally with BTs you want the workout or outdoor effort to push you to a failure point to fully express your signature.

A predicted PP of 1687 is theoretically possible if all other power curve values are in line. However, yours aren’t.
Both all-out slope efforts actually measured below 1300 watts.
Take a look at the Activity Table and enable Max Power as a column. Is a power spike shown?
An over-inflated PP calculation will raise HIE too much which in turn lowers LTP relative to TP.
If you want to prove your PP is higher than 1300, try this workout when your form is fresh.

In the future I suggest any of the “fitness test” workouts be ridden in slope mode.
By riding in slope mode the entire workout you can overshoot watt targets (if able) and extend interval duration to a failure point on the toughest intervals.
While one BT workout (Version 3) is expressly designed for trainer control (AUTO in EBC), the assumption is your signature is close to dialed in and you will ride the toughest intervals to a failure point.

Ridge, thank you for the detailed response and subsequent questions.

The workout was performed with the auto setting so I presume it put my trainer into 5% slope for the sprint portions. I know it used ERG during the rest of the intervals because I’d been adjusting gears for noise and smoothness.

I’ve never used the previous button so thank you for that discovery. It was indeed the latter–I went all out until the interval was deemed over. As you can see, power drops off significantly and that was a result of knowing that my 7-10 seconds were up. Yes on the power spike and ouch on the butterfy workout.

Understood on using slope the entire time. Auto just lets me leave the thinking out of it while my brain recovers from the hard efforts.

So, in the end, you still recommend I flag this activity and just use the old modeled curve to suggest my training? I have also edited the numbers under fitness signature, making PP 1289 and threshold 234, which seems to change my overall fitness signature numbers. Or is that a bad thing? I just know that I’m definitely not sitting at 190ish FTP and making 1600ish max watts…

Yes, leave that activity flagged. :slight_smile:
You can also adjust your HIE which will tweak your LTP.
The chart in article below shows the normal bell curve relationship between PP and HIE.
Median for 1300 is around 26.x.

Reference –
Are there errors in my Fitness Signature? – Xert (

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