MUSCLES ENGAGED Abdominals The abdominal muscles (abs) provide movement and support to your core area. The deeper and closer to the spine the particular abdominal muscle is, the more effect over body posture it will have, and this often contributes significantly to a healthy back. Equipment Used Pull Up Bar A pull-up bar is a straight steel bar that mounts on a wall, door frame, squat rack or cable machine. It is one of oldest and most effective strength tools and is used to target the latissimus dorsi muscle (lats) along with the rhomboids, shoulders and biceps. Exercise Instructions Step 1 Hang on the pull-up bar with your hands slightly wider than your shoulders. Step 2 Without bending your arms, pull your body back by activating your lats and pull your knees up to your elbows. Step 3 Come out of the tuck position and when your legs are fully extended, immediately pull your knees back up.