Back building exercises: any time you pull your elbows back and retract your shoulders, you're working on some part of your back, or your posterior side of your upper body. There are so many muscles involved in pulling motions: trapezius, lats, rear deltoids, infraspinatus, rhomboids, erector spinae... and you have to train them all. Pretty soon you'll be getting a huge series on how to train every aspect of your back on my YouTube channel. In the meantime, it would be great if you checked out what I already have up there!
Ha ha never think you know everything, I am on round 6 of Body Beast, that is a long time doing this workout and today I realized that at the end of this workout when you spell "beast" on the ab move that your head and shoulders are supposed to be slightly lifted off the ground, ha ha I am so in the zone I do not notice everything, but I am always catching something I'm not doing exactly right, always learning!! Working out is not about being perfect, it's about waking up each day trying your best and making progress!