How is blood oxygen reading different from VO2 max?

Background:

https://en.wikipedia.org/wiki/VO2_max

https://en.wikipedia.org/wiki/SpO2

SpO2 measures the oxygen-carrying capacity of blood, while VO2 Max measures the peak oxygen usage during exercise.

Sp02 measures how efficiently your blood can carrying oxygen, while VO2 max is how fast you can use that oxygen.

There are various metabolic conditions and diseases which can skew these readings, too.

Please start your own thread for this. Your question is fundamentally different.

When you do re-post this, please indicate which watchOS version, and what else you’ve tried.

Also whether there might be anything effecting or obscuring the sensor readings.

Your exercises must typically be twenty or more minutes, at a sustained and elevated heart rate.

At least on past watches, that was a vigorous outdoor walk, or an outdoor run.

But again, please start your own thread here as your “VO2 is not showing” is different from this “what is the difference between VO2 Max and SpO2?”.