every action; every single move
Refers to all of someone's actions, often in contexts of close observation or scrutiny. Common in phrases like 一挙手一投足を見張る (watch every move).
He didn't miss a single move she made.
slight effort; least trouble
Used in negative or minimizing expressions to indicate that something requires very little effort. Often appears as 一挙手一投足の労 (the effort of a single move).
Don't begrudge even the slightest effort.