[beingfit]

> I wonder how it estimates VO2Max and how often depending on the model. On my Series 3, it seems to make a data point two or three times a month and it’s concerning to me because it seems like it isn’t trending up even though I have started to do more cardio exercises.

The description in the Health App under Cardio Fitness (the one that shows VO2 Max) says that it measure it only for outdoor walks, hikes and runs. If you don’t do these outdoor activities, it won’t measure or record VO2 Max. I’ve seen this reflected in my measurements. I do HIIT and cardio workouts at home, and it certainly doesn’t measure or record VO2 Max.