With a bench or box, set up in a reverse plank with your shoulders on the bench with active arm hanging off to the side of the bench, palm pointed towards your toes. * Keep your hips elevated to maintain the reverse plank position throughout * Lower your arm to the side, ending with your upper arm at ~45* angle to your torso * Press back up, ending with your wrist over your shoulder. * Reposition on the bench to complete reps on the other side.