Originally Posted by
ZHVelo
VT1 is basically Zone 2?
Somewhere in Friel's Z2 defined relative to experimentally determined Lactate Threshold Heart Rate. Unknown with a system based on a hypothetical 220 - age maximum where there's a 12 BPM standard deviation making you real maximum somewhere between 184 - age and 256 - age.
Use the subjective definition.
Supposedly it also lines up with LT1 1mmol/L blood lactate concentration.