Apple

No not really. Have you seen how they acutely do these measurements? The numbers are wayyyyy off it’s basically just guessing, don’t worry about it!

No, it’s whack. Turn off the alert.

Watch estimates my VO2 max at 25. Other estimates put it at 45-46 based on my min/max heart rate, which aligns more with my actual fitness. I don’t record Apple workouts very often though, I often use it as a Peloton HR Monitor.

Try this:

(max heart rate on an all-out, gassed workout / resting heart rate) * 15.3

Disclaimer: Not a doctor nor a watch.

I go to the gym 5 days a week. I don’t do cardio as often as i should. My vo2 shows low.

Like others have said, take it with a grain of salt but usually a trend is a trend - one thing I did find out recently is that it’s more accurate when you workout across flat land?

There have been multiple tests where people get a proper VO2 test done on the treadmill etc and it's pretty accurate. My Garmin watch says 49 and my Apple Watch says 45.4. I think the Apple Watch is probably more accurate as I've worn it for years whereas the Garmin is only a month old. The more runs you do, the more accurate it will be. Whilst I understand that it must be discouraging to be in that range, if you put the effort it, the only way is up :)

Cardio Fitness is a very good indicator of the level of your aerobic efficiency and how it evolves overtime