Thoracic Bridge

From a hands-and-knees position, thread one arm underneath your body and rotate your chest down and across, then reverse the motion and open all the way up, following your hand with your eyes as it reaches toward the ceiling. Your hips stay level throughout — the rotation belongs entirely to your upper back, not your lower spine or pelvis. Keep your supporting arm firm rather than letting your shoulder cave in as you turn. This is about finding rotation that's been sitting unused in your upper back, so move slowly enough to feel where the motion runs out rather than forcing it with speed.