This is perhaps more apparent in a fencing match, since the fencers may only move forward and backward. The 'fencing measure' is a central consideration for a fencer. It is the distance which a fencer keeps in relationship to his opponent, and is such that he cannot be reached unless his opponent lunges.

Now imagine that you're in your boxing gear while standing on a fencing line. Your opponent stands at a 'fencing measure' in front of you. How would hit them?