I do not intentially split aerobic and anaerobic threshold (aka Lactate Threshold) into zones. All is continous, I contend, in the energy spectrum.
For example, in my view, running 4 miles at 4 mmols (LT) is equal to 8 miles at 2 mmols (Aerobic Threshold) is equal to 16 miles run slowly at 1 mmol. Tinman
I do not follow this. The body reacts to most training in an exponential fashion rather than a linear fashion as your statement suggests.