I’ve been training my sprinting. I decided to see how my improvement was going by doing a 30 s test. I did great (for me). My xert ebc said I had a breakthrough but xert online is not saying that. My power curve for that event is strange. My interval is above my power curve.
What is going on? I really don’t understand. (Happy to be improving though 
)
How short was the effort? Can you post a screenshot of the power chart?
When EBC chimes in with a BT alert it’s best to keep pushing to a failure point if you can.
The apps include a slimmed down version of the BT detection algorithm.
When the activity is uploaded to the server a second-by-second analysis occurs along with some “noise” filtering that the app isn’t capable of providing.
Thanks for responding!
It was a 30 s effort. If I hover over the red point that is above the power curves on the picture above, it says 394 00:30. The power curves are 376 for 00:30. The picture above is the Power Duration tab for the activity. I set it up to be a 32 s interval on slope mode as I know that it takes time to spin up.
Below is the MPA analytics plot from the same event.
I understand that the EBC can get a different answer from the server, but to me the server is getting 394 W for 30s as shown the first plot. (For reference, Garmin analyzed to 397, Zwift and Strava to 396… so all similar to the 394 here.)
Zoom in on the green dot section.
Compare that to the type of efforts that generate BTs as shown in the examples here –
Breaking Through the Xert Way! (pull down, push over, or multiple) – Xert
I think a few more seconds would have resulted in a BT on the server. Or a second max effort shortly after the first would have flatlined MPA as the examples show.
OTOH a short maximum effort that ends abruptly may trigger a false BT that should be flagged. This typically occurs during a race (indoors or outdoors) where a max sprint to the line suddenly drops to zero watts rather than fail naturally.
So the algorithm is based on the second plot. That means that it is, if done in a specific way, possible to ride an interval almost 5% higher than your xert power curve.
Would you suggest, I reset my power curve so it is a maximal curve? I know the best would be to redo the interval and go 34 s instead of 32 s but I have a race series starting and need to get my legs out of the yellow.
Hey @susanallen !!
Great observation and question.
Indeed it is possible to outperform your power duration curve. Your PD curve is calculated based on a steady power effort until your MPA = Steady Power. If you have variable power, you could technically finish the effort with MPA below this power and end up with a slightly higher average. This is what you’re seeing. It’s a very interesting aspect of performance and suggests that a slightly positive split will outperform a neutral/negative split effort. Interestingly, positive splits happen all the time due to MPA decreasing as the effort progresses so the body seems to want maximize the effort naturally.
