I have programmed my 2nd marathon event on April 2nd, 2017 and was looking into the pre-built Garmin Connect programs, that utilize HR monitors. Got a couple of questions though:
1) The HR-based programs reference zones Z2-Z4 AFAIK. Can I use LTHR-based zones for that purpose? If so, to which Friel Z4 zone do the Garmin programs correspond, Z4 or Z5a?
2) On the same context, some of the runs take place on Z2. Is it the same zone as Friel's "Aerobic Threshold"?
3) I've got to decide whether to follow the level 1 (3 practices per week) or level 2 (5 sessions per week). If I want to do 4 sessions, can I cut down some of the days safely? If so which one, Wednesday perhaps? Or is there something else needed, like moving Wednesday's program onto Thursday?
Apologies for the many questions, I'm trying to figure things out and I've been buffled with all the different terminology regarding HR zones etc...