You can think of warm-up as the picture of something cold being brought up to temperature before it is asked to work. A body straight off a cold bench is stiff; ten minutes of easy movement makes it loose and warm, and only then does the real effort begin. Everything the word does keeps that shape: a small, light, low-pressure run at the thing, placed right in front of the thing itself. What gets warmed can change — muscles, a voice, a set of tyres, a quiet audience — but the position never does. It always comes first, and it is always easier than what follows.