HOW: Get into the tall plank position on your hands. Push the ground away from your and protract your shoulder blades. Slowly lift one arm away from the ground. From this position, slowly relax your shoulder blade muscles to lower your body slightly - without bending your elbow. Then re-engage those same muscles and push the ground away from you once again.
FEEL: You should feel all the muscles in your shoulders and chest working, in addition to your core. You should feel 'strong' in this position like someone cannot push you over.
COMPENSATION: Try to keep a neutral spine and flat back. Widen your stance if needed.
