She grins. "Ah. A good question." A nod, and she demonstrates the posture she means. "Here, see...you are low, and your legs bent. When you hit, your legs push to add to the impact. Also, see..." she stands upright. "Here, the force behind the shield is arm and one shoulder. Good, but...." back to the low posture. "Here, it is arm, shoulder, and upper torso. More solid. Understand?"