[dorfsmay]

> VO2 max (a measure of aerobic fitness)

Note that even though we used to be told that we could all increase our VO2 max through trainning, it turns out that only people with a specific set of genes can do so.

[irv]

in the sense that there is a personal ceiling for you, yes.

but if you've never trained at elite level, then you can almost certainly improve it up to your (personal) ceiling.