Open your chest and twist out a stiff upper back.
Let the rotation come from your upper back, keep those knees glued together.
Pinning your knees together on the floor locks the lower body down, so when the top arm sweeps open the rotation is forced into the thoracic spine, exactly where desk-bound backs are stiffest. The chest opens toward the ceiling while the mid-back untwists, one side at a time. It is the go-to mobility drill for anyone whose upper back has forgotten it can rotate.
A few slow breaths per rep works well, either held or flowing gently in and out of the position. Ease further into the rotation on each exhale rather than forcing it.
Yes, lifting knees means the rotation is leaking into your lower back instead of your upper back. Put a cushion between your knees, press them down deliberately, and accept less rotation for now.
Before upper-body training to prep the shoulders and mid-back for pressing and rowing, and any time after long sitting. It costs a minute per side and pays off immediately.
