There are some 'time travel' stories where the protagonist, hailing from a modern age, does stretches and warmup exercises (calisthenics, radio, etc) and the natives have no idea what that is.
There's also this old comic from Gary Larson's The Far Side depicting Viking warrior stretching out.
It begs the question, did they do any sort of warmup or stretching before exercising, training, fighting a war?
When was the first recorded case of the use of these exercises, in any form, in history?
Mostly interested in ancient-history.