@klaus said in Apple Watch - health metrics:
But wouldn't the watch need to know what kind of physical activity I'm performing (and the intensity) to make any guesses about VO2max? Or do you tell the watch "now I'm going to walk a mile at moderate pace" or something to get an estimate?
The VO2 max estimates can only be made for an outdoor moderate walk, run or cycling workout. It uses GPS (pace), heart rate and maybe some other health factors (gender, age, weight, etc.) to spit out an estimate.
The watch can detect a walk or run (and will ask you to confirm if you're working out) - but you have to tell it that you're about to cycle.
If you don't do one of those 3 activities - you won't get a VO2 max data point.