The longissimus thoracis is one of the three parts of the longissimus muscle. The longissimus muscle is one of the deep muscles of the back, grouped under the erector spinae muscle group. It runs from the ninth or 10th rib of the thoracic region to the top of the sacrum. The three longissimus muscles flex the head and neck and rotate the spine.
Alternating Bird Dog
To target all of the erector spinae muscles, including the longissimus thoracis, try the bird dog exercise. Kneel on a mat on all fours with your hands below your shoulders and your knees below your hips. Raise your right arm straight out beside your head while you lift and extend your left leg out behind your body. Lower both arm and leg to the floor to the starting position and repeat with your left arm and right leg. Complete the movement without jerking. Alternate back and forth between left and right sides for the duration of the exercise.
One of the compound exercises that targets the longissimus thoracis and erector spinae muscles is the deadlift. Place the barbell directly in front of you so that your feet are under the bar. Squat down and grasp the bar in an overhand or mixed grip with your hands shoulder-width apart. This is your starting position. Extend your hips and knees to lift the bar. Do not use biceps to lift the bar or allow your shoulders to round out. Return to the starting position to complete one rep.
Back Extension on Stability Ball
Use the back extension exercise to work the longissimus thoracis and other muscles of the erector spinae. Lie face down on your exercise ball with your feet flat against the base of a wall. Put your arms against your sides or clasp your hands behind your hips. Raise your torso off the ball by hyperextending your spine. Lift up until your body forms a straight line from your shoulders to your knees. Return to the starting position for one rep.
To finish your workout, try the superman move. Lie face down on a mat with your legs together and your arms straight out in front of you. Slowly raise your upper body and your legs up off the floor as high as you can. Pause and then return your upper body and your legs to the floor to complete one rep.