Substrate utilisation estimation
It would be nice to get an estimation of the substrate utilization (FAT/CHO rates) like the INSCYD test does.
If necessary, for better estimation, there could be used a defined test protocol for the estimations. Also if this is the case (and an auto select doesn't lead to desired results) it would be nice just to select the Lap in the workout view and tag it as Test (right mouse click, tag as 20s test or so on.).
A Theory of the Metabolic Origin of "AnaerobicThreshold (A. Mader, H. Heck 1986)
Glycolysis and oxidative phosphorylation as a function of cytosolic phosphorylation state and power output of the muscle cell (A. Mader 2003)
should be a very good starting point.
I also know this just would be estimations, but imo. science based estimations are better than digging in the dark or just estimate anything without basis.