Firstly let me say I appreciate that TR is a wattage/FTP centric product and I may be trying to compare apples with oranges, but…
Bird -1 is an anaerobic workout and therefore I would anticipate my heart spending a fair period of time in Z4 and Z5 during the 15 minutes of effort.
I have noted that I have spent 6 mins in Z3, 6 mins in Z4 and no time in Z5.
So the question is, will this workout be achieving the desired physiological effects or should I be swapping it out for something with longer efforts and/or shorter rest periods to make the cardiovascular system work harder?
Appreciate your comments.