How do you explain the need to stretch?!
Question:
How do you explain the need to stretch?
Answers:
Are you asking about the need to stretch as a benefit before working out? Not so much need, as damn good idea.
But I think you are asking about why sometimes we have to stretch. It's an urge, and offers relief. Much like yawning - in fact, just like yawning.
Your muscles are looking for a little more oxygen, which we have in our blood going to the muscles. By stretching, you expand the volume of the muscle and speed up the flow of blood. Therefore more oxygen quicker.
In case it needs explaining, the oxygen is what your muscles use as fuel. (Well, part of it anyway.)