Upper Back Pain | Posture This exercise improves thoracic spine mobility while strengthening the muscles of the upper back. By moving the spine through controlled flexion, extension, and rotation, stiffness between the shoulder blades starts to ease. At the same time, the upper back muscles learn to support the spine instead of constantly tensing up. Over time, this combination helps: • Reduce tightness and knots between the shoulder blades • Improve how the upper back moves and loads • Take str