Can anyone explain to me why Tempo shows up as my dominant zone when I spent most of the ride in the Endurance zone ? Thanks 
I almost can I worked with Mark at Golden Cheetah on this about 5 years ago but the idea is the zone that has the dominant effect on your body. He had an analysis of a thousand riders at that time. So in this case the tempo has a larger effect on the workout than zone 2 does.
There is a deeper analysis of how this was validated but now I don’t remember it. It seemed very clear at the time. I could get the formula from the code.