$VO_2$VO2​​ Max – The maximum amount of oxygen your body uses while exercising as hard as you can

(Pronounced vee-oh-too max)

The way to remember the meaning of $VO_2$VO2​​ Max is to consider the following:

VO is the start of volume

$O_2$O2​​ everyone knows is oxygen

Max is the start of Maximum

So, $VO_2$VO2​​ Max = volume, oxygen, maximum

or:

$VO_2$VO2​​ Max is the maximum volume of oxygen your body uses (while exercising as hard as you can).

To find your $VO_2$VO2​​ Max you would need to visit a special centre/testing lab. You'll put a mask over your face that captures the amount of oxygen in your breath. While wearing the mask, you'll run on a treadmill as intensely as possible.

The higher the individual's $VO_2$VO2​​ Max, the better aerobic fitness they have.

There are two types of $VO_2$VO2​​ Max:

Absolute $VO_2$VO2​​ Max. Your absolute $VO_2$VO2​​ Max is simply the amount of oxygen you breathe in litres per minute.

Relative $VO_2$VO2​​ Max. Relative $VO_2$VO2​​ Max measures the amount of oxygen you breathe per kilogram of bodyweight. 

Example

1/  David weighs 100kg and has a $VO_2$VO2​​ Max of 4000ml/min

Therefore David's relative$VO_2\text{ Max}=\frac{4000}{100}\text{ = 40ml/kg/min}$VO2​ Max=4000100​ = 40ml/kg/min​

2/  Sarah weighs 57kg and has a $VO_2$VO2​​ Max of 2500ml/min

Therefore Sarah's relative $VO_2\text{ Max}=\frac{2500}{75}\text{ = 44ml/kg/min}$VO2​ Max=250075​ = 44ml/kg/min​

Conclusion: Sarah is aerobically fitter than David and can sustain intense cardiovascular exercise for longer.