When the waist drops then energy can sink to the feet. To allow the waist to drop the back at the Mingmen point slightly presses out. The perineum drops as the tailbone straightens slightly, and presses down. This will allow the chest to become very slightly concave, empty and allows an arch across the back and shoulders horizontally, and vertically from the base of the neck to the base of the spine. As the tailbone drops let the chi sink to the feet.