Your latissimus dorsi (your "lats") is a broad, flat, triangle-shaped muscle that spans your middle and lower back and extends to the front of your humerus (upper arm bone). It plays a role in ...

The latissimus dorsi, to use the muscles' proper name ... with your legs spread wide and your elbow in front of you in an externally rotated position. Lift the dumbbell, keeping your hips low ...