HRDM only applies to activities with no power data in the FIT file.
Yes, the chart makes sense if the ride was 1) all out and 2) the rider is well trained and capable of pushing to their limits like that.
The screenshot is clipped but I assume the activity indicates 5 diamonds and the title is something along the lines of “[abso]lute full gas”.
If that doesn’t reflect what happened Xert provides the ability to play what-if scenarios and tweak a signature. That is another feature in Xert’s toolbox.
Scroll through posts in this topic to find examples of unusually high DS –
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This includes cases where manually raising TP a point or more would correct a signature that is underestimated by the algorithm. No model is infallible. 