Training anatagonist muscle groups.

[user67987321321654]

I was told in order to prevent injuries you need to train your whole body with the same amount of work - for ten pressing movements do ten pulling movements.
Biceps - Tricpes
Chest - Back
Quads - Hamstrings

One thing I do not understand with this concepts are the angles, though.
Personally, I do not train my chest directly at this point - it's only a matter of taste as I do not like big pecs on me.
I do military presses, though, which train the upper chest to some extent. Would the only real antagonist movement be pullups, or do barbell rows belong into this category as well? Actually the bench press is the anatognist movement, but military presses are still a pressing movement, while the barbell rows function as a pull.
Is it all about the shoulder? If so, is it about the angle?

Thank you so much!

[user67987321321654]