Workout XSS significantly different

This morning, I rode the Galvanize workout on my Wahoo KICKR Core. The listed XSS is 157. In reviewing the activity detail from my ride, it shows only 108. I rode the workout in auto mode. I hit or was very close to all power targets. What explains this difference?


Welcome aboard.

I suggest you select the activity from the Activity tab in XO, click on the Public Activity toggle button in upper right, then post the URL here so we can review the results.
Did you select this activity manually from the library or was it on the recommended list?
What is your current stars status count?

I selected it manually from the list.

Currently, my fitness signature shows 3 stars.

It is not unusual for a completed workout to differ from the predicted XSS. In some cases you will exceed the estimate. A lower number would normally indicate a failure to hit/maintain targets, but obviously you did complete the workout as designed.

Someone more knowledgeable than me will likely chime in but at quick glance the difficulty (intensity measurement) wasn’t high enough to generate the expected strain score (XSS). IE, the workout was easier than forecast.
My guess is a signature mismatch is the culprit as it appears the workout generated a BT (breakthrough). If yes, view the activity, click on Advanced MPA tab, Previous button to display the analysis with your prior signature values. You can zoom in on the BT section to see details. Areas where MPA was drawn down below target watts indicate the BT event(s) especially sections that show MPA flatlining.
BT activities also display a BT icon badge next to Cycling Summary (above title). You can click on that icon to generate a downloadable report to post here so we can see the delta.

I also suggest you enable advanced charting under Account Settings, Advanced Charts toggle.
Introducing New Insight-Rich Colour-Coded MPA Charts – Xert (

I suspect the XSS listed is a mistake. In the analytics, I had it show the power targets and they looked in line.

Here is BT download link.

It’s as @ridgerider2 says - the breakthrough increased your signature, and the XSS is for the new, higher signature, and therefore lower than what it would be on the old signature (lower % of threshold and you didn’t ride for 2 x 15 min at 200 XSSR relative to the new signature).

Okay. I just did the Advanced MPA and saw the change in the XSS. My next question is which XSS is used to update the adaptive training model. I usually see deficits or surpluses expressed in terms of XSS,

XSS is shown under XO, Activities, Table or under Planner tab, Weekly Stats
XATA is based on a rolling seven days using a weighted moving average.
No need to worry about a day’s deficit/surplus as the figure evens out over the seven days. Your goal is to keep the pacer needle between 11am-1pm to stay on target.
I had an XSS Training Surplus of X yesterday but today I have a big deficit of Y. What’s going on? – Xert (

Forgot to ask if you had seen this thread already (lots of newbie tips there) –
Beginner questions - Support - Xert Community Forum (

That 14 watt jump in TP explains the lower XSS value generated for the activity.
Had your updated signature been in effect when you started that workout each of those red spikes would been harder and the threshold level 2x15’s would have accumulated more strain as @wescaine mentions.

One of the unique features of Xert is you can view your current fitness signature applied to a workout by opening the workout in Workout Designer. Note the MPA and Difficulty lines below when I open ‘SMART - Galvanize’ with my current signature. This is the predicted outcome which may differ from actual results depending how well I perform the workout and whether a signature adjustment is warranted (BT event occurs during activity).

Compare this to the Difficulty measured in your activity with the updated signature.

The Difficulty line in particular indicates where XSS accumulates more as you continue to perform while fatigued.

Reference –
Xert Strain Score – Xert (
Difficulty Score – Xert (

The one based on your new signature. So yes you have a small gap which you can catch up over time… and for added good news, you’re workouts will be quite a bit harder now, and it will take more effort to reach the same XSS :wink:

That’s another reason it’s good to try and keep your signature fresh. Was that last workout actually ‘all out’ and to failure at the point of the breakthrough? Given you completed the workout afterwards I suspect you may have had more power available… so it’s probably worth doing a proper breakthrough effort next time you are fresh (including some all out sprints, maybe in a separate day). There are other threads on the forum re getting good breakthroughs if interested

Currently, I am following a 12 week training program on a different training app. I am using Xert workouts primarily for the analytics. I do perform Xert workouts on scheduled off days. When I do perform workouts in Xert, I perform them in auto mode. If I understand the Xert modes correctly, to achieve real breakthroughs, I would need to perform Xert workouts in slope mode or auto mode at a percentage greater than 100%. Is this a correct understanding?

Yes preferably in slope mode so that Xert can see the pattern of your fatigue… doing it in auto (even at 110%) then stopping / dropping to zero immediately can cause issues with the signature (allocation between TP and HIE)