Hello. I have a question about the intensity of zones uses to illustrate the kind of plan follow by the athlete
The polarised /pyramidal/ linear… are justified by Time in zones 1/2/3 in a 3 zones model.
Here, intervals use a 7 zones model. Knowing that z4 is above the SL2 why intervals.icu tale the z4 zone into the z2 of 3 zones model ? I assume that it may be very difficult to realise polarized program without taking acount of the Z4 zone.
It all depends on what zone system you’re using.
In Cogan Power, probably the most used, Z4 is 95 - 105% FTP.
But no-one stops you from defining the zones differently. There are several other zone systems.
I use HR/Power/Pace zones that align top of Z4 with Lactate Threshold.
Intervals was originally setup with the Cogan 7 zone Power system and this is something that is quite difficult to change now. The easiest way to handle a 3 zone system was to group, Z1&2, Z3&4, Z5 and above. But again, you can do almost anything you want by modifying the zones. Except if you want LTHR at top of Z5 for example.