I have used the apple watch in training, and in 2020 I registered a steady increase in vo2-max, right up until December. After that, the vo2-max number suddenly one day just started to go down, and it has done so ever since . It just goes down. I wonder why this is so, and if it may have something to do with changes in the clock settings? I do not train differently and I do not train anything less than before this happend.
Try resetting the fitness calibration data
From your iPhone>Watch>Privacy>Reset Fitness Calibration Data>Tap this
You will just get a confirmation box that tells you that your metrics will not be as good if you do this.
Tap confirm and do it. You will get nothing else, no confirmation but it is done.
Then go for a 20 minute outdoor run or walk using the workout app at your normal speed on a flat road/path etc
This will re-calibrate the watch.
Vo2 Max
