The thoracic spine makes up the primary curve of the spine flexes out of your back. Thoracic spine extension exercises help you strengthen the muscles that pull your shoulders back and prevent a hunched-over posture, according to fitness professional Anthony Carey, author of "Pain-Free Program."
Passive Scapular Retraction
This exercise uses gravity to help you passively retract your shoulder blades together and relax tight muscles in your lower spine. Kneel on the ground with your hands beneath your shoulder blades and your knees below your hip joints. Relax your abdominals and allow your lower back to extend toward the ground. Relax your neck so that it is hanging down to the ground. This will cause your shoulder blades to naturally pull together without conscious effort. Hold this position for 10 deep breaths. Return to the starting position and repeat this exercise twice.
Foam Roller Spine Extension
A foam roller is a long, cylindrical tube that is used for self-massage. You also can use it to help you extend your upper spine and open your chest cavity. Sit on top of the foam roller with your feet on the ground. Slowly roll your spine down the roller and cross your arms over your chest. When you roll up to your shoulder blades, press your tailbone gently to the ground and slowly tilt your head back. Put your hands behind your head with your elbows out to the sides. Lean back only as far as your flexibility will allow. Hold the stretch for 10 deep breaths. Repeat this exercise twice.
Supine Spine Rotation
This exercise helps you determine whether both sides of your upper spine and shoulder girdle are balanced, which can improve your upper spine extension. Lie on your right side of your body with your knees bent up to the torso at about 90 degrees and your arms extended in front of your chest with your palms together. Turn your torso to your left and lift your arm up and over your body to touch the ground toward your left. Do not move your knees out of place. Hold this stretch for three deep breaths, and return to the starting position. Perform 10 reps on each of your body.
Too much thoracic extension can cause you to reduce the natural curve of your spine that keeps you in balance and in alignment. This leads to upper back and lower back pain, back tightness and stiff shoulder joints, according to physical therapist Gray Cook, author of "Movement." You spine should appear more like a letter S rather than a straight line with little curves.