Choose a stable chair
Use a firm chair without wheels and place both feet flat on the floor. NHS sitting guidance uses this stable setup for seated movement. The chair back should meet the upper back rather than only the lower waist. If its height does not suit you, choose a different chair instead of forcing the shape.
Position the upper back
Sit tall enough that the top of the backrest is just below the area of upper back you want to move. Keep your hips on the seat and hands resting comfortably. You can fold the arms loosely across the chest if that feels easy. Do not pin the shoulders down or push the neck backward to create a larger movement.
Lean back a little
Gently let the upper back move backward over the chair edge while the feet stay planted. Make this a small, slow exploration rather than a deep stretch. Cambridge University Hospitals and OPAL guidance describe this seated upper back direction. Their clinical repetition counts are not general instructions for everyone.
Return with control
Come back to your usual upright seat without throwing the head forward. Pause and notice whether the motion was mainly around the upper back. If you felt only a large arch in the lower back or a strained neck, reduce the range, change the chair or skip this version. Comfortable control matters more than how far you lean.
Compare other directions
Seated thoracic rotation turns the upper back rather than extending it. Seated side bend moves sideways, while Cat Cow changes spinal shape on hands and knees. Choose the direction you actually want to practice. The beginner mobility guide helps place short movements in a wider routine.
Keep the range comfortable
Breathe normally and keep the movement unforced. Stop if pain, dizziness, numbness or another unusual symptom appears. If a recent injury, surgery or personal restriction affects your spine, get individualized advice before trying it. This is a movement option, not a promise to treat a condition or improve posture.