What he said –^
From my basic understanding, it’s just a number, you can train it up if you’re unfit, and monitor it over time to see the effect of training, but you can’t really do anything with it whilst actualy training.
Unlike say power, which gives you a nice curve to show your thresholds at various time durations which is closer to real life, you don’t just jump up through 5 or 6 discreet zones. If yout to know if your VO2max is above/below what it should be, look in the “trainig with a power meter book” at the table, if your 5min power is further up than your threshold, then you’re distorted slightly that way, if it’s on a lower line you could probably train it up a bit (or maybe your Bradley Wiggins).