At YogaWorks, we've developed what we call the "shoulder girdle" mantra to describe the actions to take to keep your shoulders in alignment in this posture and many others. We call it a mantra because it is a series of instructions that, once learned and understood, can serve as guidelines to illuminate and transform your practice. Unlike a traditional mantra, it has no spiritual component—just a set of orienting principles that you can come back to again and again, especially when you find yourself at a loss about what you should be doing with your shoulders in a given posture. The mantra is based on correct alignment in Tadasana (Mountain Pose) and can be applied to a multitude of poses.
Play with it here in Parsvottanasana (Intense Side Stretch) as an opportunity to discover the back-bending elements that make this forward bend so delicious, and then see what happens when you thread it through the rest of your practice. You may find it very useful!
"Extend your sternum away from your navel." This helps to create length along the front of your body, as in Upward Bow Pose.
"Spread across your collarbones." This establishes breadth across the front of your body, as in Low Cobra Pose.
"Draw the heads of your shoulders back to align with your side body." This keeps the pectoral area open and broad, as in Camel Pose.
"Soften your trapezius muscles, and release them down your back." This helps to prevent the buildup of tension in the upper back, as in Bridge Pose.
"Broaden your shoulder blades and move them into your chest." This opens the heart and supports the front of your body, as in Upward-Facing Dog Pose.