Puzzled by ups and downs of numbers

I’ve been mostly doing recommended workouts, with a weekly ride or two outdoors, but now it’s getting cold so I’m mostly training indoors. My TP has been slowly going down while my HIE has been slowly going up, untii today. I did a Wahoo Systm (aka Sufferfest) ride that was short with high intensity (20x(15 second high intensity, 15 second rest), few minute rest, 22x(same 15 second intervals with one 30 second one at the end.)). I expected my HIE to go up and my TP to stay the same or go down. The result, with a TP breakthrough and a big HIE drop, was the exact opposite (show in picture with previous numbers and changes from the ride). What am I misunderstanding? I’m a “GC specialist” with “Moderate-1” continuous improvement rate.

That looks like a valid adjustment to me especially considering the new improved signature detection algorithm and the fact you flatlined MPA multiple times at the end of the second set.
See this article for details –
Improvements to Fitness Signature Detection – Xert (baronbiosys.com)

Also, note the bell curve relationship between PP and HIE in this article –
Are there errors in my Fitness Signature? – Xert (baronbiosys.com)

When is the last time you selected a sprint workout to ride indoors or outdoors?
For example, SMART - Bullet with Butterfly Wings
You don’t need to complete the entire set. Do as many as you can before you start to fade.

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Thanks for information - it was very useful. I’ll try out the sprint workout but my suspicion is that it will not change much because my PP and TP numbers are close to what I’d expect. In Sufferfest, when I did their dreaded “Full Frontal” test, I’d get upper 600s for my 5 sec. sprint wattage and upper 170s for my FTP, but always be labeled a “Pursuiter” because my 5 minute power was relatively high (235). I’m not sure how to translate HIE into a 5 minute power rating, but if the bell curve in the article about the relationship between PP and HIE is correct then Xerts new ratings are probably about right because they show a relatively high HIE but not one totally off the charts as my previous HIE was.

Exactly what does the flatlining of MPA indicate?

Flatlining refers to what occurs to the MPA graph during a BT event.
In your case you had multiple BT points during the second set.


For details see: Breaking Through the Xert Way! – Xert

This had a correction due to the new extraction algorithm. Your HIE was much too high for your Peak Power and now it is more in line. Keep up the good work! If you continue to work your High Intensity system, you should see increases in HIE that should respond more predictably to your training as a result.

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