this is Eileen Troberman explaining a warm up (2 videos in the series) and another video on cool down. she emphases how to lengthen the body. All these are really an awareness of your body with the Alexander Technique. worth exploring:
There's also an exercise in breathing, vollowing the same lengthening of the body and being aware of it lengthening. Interesting, as it is gentle,
perhaps this is for COPD people as well as musicians!