Out of curiosity I have a naive question... Does anyone have any idea of how Garmin calculates VO2 Max and what values they use?
I assume they use the latest resting HR or some average of that over some period. I assume they use some value of MHR, but do they use what you actually hit in a recent workout? What you enter as your MHR or barring that what they are using as your MHR in setting zones ( the former doesn't seem like a good way to go and the latter would seem particularly useless)?
They have a lot more info available than just HR numbers, durations, trends, rates of change. Not sure if any of that would be useful for this.
They could maybe use power data, but I know they don't in my case (no power meter).