Ya know, I think the best course of action to solve this question is to go to grandma and hear what she thinks.

It is both. Stretching is a kind process that prepares both your mind and your body for the work is coming ahead. It is absolutely necessary to get your body to produce the maximum output. It’s like having a small cup of tea before you force your heart rate to 190 (short of a heart attack,) Someone else mentioned , you have to warm up, then stretch. Then workout, then stretch as a cooldowm to achieve fficiency.