I've not had any Vo2Max recorded for the last month, my fitness age has been increasing due to lack of vigorous minutes despite doing more brisk walks/cycles. Turns out Garmin want you to have the HRM pro to count intensity minutes and if you wear the normal Garmin hr monitor during an exercise it does not count!!!!
The blue graph is my heart rate as recorded by the venu 2 and never got above 118bmp. The red graph is the cycle from the blue graph and recorded with the Edge 530 and chest HRM due to the poor performance of the Venu 2 optical sensor.