What quantity am I saying here?

You are saying 3 million in total.

"Athletics" is awkward, incidentally. You appear to mean "athletes".

S L Bayer, in ... Events and Arguments in Compositional Semantics discusses the different (and sometimes conflicting) usages demanded of 'and'. He concludes that say

• 'ten men and women'

is ambiguous ... not because some people use 'and' constructions in idiosyncratic ways, but because the ways 'and' is used in 'Standard English' necessarily give rise to alternative interpretations.

An article by L Champollion top link here (reformatted) has:

... collectively interpreted conjunctions of plural nouns are in principle ambiguous as to the number of entities involved. So

• five men and women

can involve reference to a total of ten people, with five men and five women ... or (more likely) to a total of five people, with some men and some women among them.

The sentence needs rephrasing if clarity is paramount.