Good posture is possible even without your mom nagging you. One key is stretching and strengthening the muscles around your shoulder blades.
For many people, proper posture in the shoulders is elusive. On the few occasions when you straighten up, you briefly taste that sweet spot of stability. Most of the time, though, you probably live in slump land-or you go to the opposite extreme and adopt a military posture, pushing your chest forward and up and wrenching your shoulder blades back toward your spine. But when your shoulder blade alignment is just right-when none of the surrounding muscles are short, tense, overstretched, or weak-it feels marvelous.
The difficulty, of course, is in finding and maintaining that posture. But it's worth the effort; not only do you look better when you stand up straight, but you'll also have fewer aches and pains in your neck and back and you'll be able to practice yoga more easily. If you spend too much time looking like a soldier at attention, the tightness in the muscles between your shoulder blades will make it harder to raise your arms overhead, whether you're reaching for a top shelf, pressing back into Adho Mukha Svanasana (Downward-Facing Dog Pose), or reaching for the sky in Vrksasana (Tree Pose). And if you slump, you probably have a hard time doing backbends and have a limited range of movement in your shoulders.
Along with their role in posture, the scapulae (shoulder blades) act as the foundation for the arms. The stability and mobility of your shoulder blades depend almost entirely on the muscles that attach to them. That's because each scapula contacts the rest of the skeleton only in a small joint at the clavicle (collarbone). Fifteen muscles attach to each scapula, and their actions are complicated, so we'll focus on just two opposing muscle groups that are crucial for both good posture and complete shoulder function: the adductors, which pull your shoulder blades toward your spine, and the abductors, which draw them away from it.
If "attention" is your default position, you need to teach the muscles that adduct your scapulae (your trapezius and rhomboids) to soften.
The "traps" lie just under the skin and run from the base of the skull and the spine out to the shoulder blades, covering most of your middle and upper back. The middle trapezius, whose fibers run horizontally from the upper- and middle-back vertebrae to the inner edge of the scapula, does much of the work of pulling the shoulder blade toward the spine. It gets help from the upper and lower parts of the trapezius: Along with pulling the shoulder blade toward the spine, the upper trap lifts it, while the lower trap pulls it down. But those actions usually cancel each other out, so when the whole muscle contracts it pulls the shoulder blade toward the spine. Immediately beneath the trapezius lies the rhomboid. Running between the upper-back vertebrae and the inner edge of the scapula, this muscle exerts an upward pull as well as a strong adduction.
Several yoga poses can help you stretch your traps and rhomboids. In Balasana (Child's Pose), you can breathe into the space between your shoulder blades to relax and lengthen the muscles.In Garudasana (Eagle Pose), you'll feel both scapulae pull away from the spine, especially when you lift your elbows and your breastbone. After you unwind your arms, imagine you're opening space for your heart and lungs, not just by expanding your chest and front rib cage but also by widening the space between your shoulder blades.
If you're like many Americans, you slump in your middle and upper back: Your chest tends to collapse and your scapulae are far apart. This is no surprise; many of us spend most of our time hunched over doing things like typing on a computer, driving, reading, or working at kitchen counters. Fatigue and depression and even exercises that strengthen your chest, like Sun Salutations, can also contribute to slumping. All this rounding shortens and strengthens the abductors while weakening and overstretching the adductors.
The primary abductor—the main muscle that pulls your shoulder blade away from your spine—is the serratus anterior. It attaches on the front of your ribs, wraps back around your side, moves into your body between the shoulder blade and the back of the ribs, and anchors on the front side of the shoulder blade along the edge nearest to the spine. But plenty of other muscles can contribute to a sagging scapula: the pectoralis major, which runs from the sternum and collarbone to the outer humerus (upper arm bone); the biceps brachii, the large muscle on the front of the upper arm; the pectoralis minor, which attaches to the front of the ribs and inserts on the top front of the scapula; and the latissimus dorsi, which originates on the middle and lower spine, winds up through the armpit, and inserts on both the shoulder blade and inner humerus.
To counteract an upper-back slump, try some chest-opening supported backbends. The support allows you to hold the pose longer and get a deeper, more relaxing stretch. Lying back over a prop that extends along your spine will elongate the serratus, the pectoralis major, and the biceps. If you're stiff, use a rolled sticky mat; if you're more flexible, put two yoga blocks in line, separating them by a few inches so the support is about two feet long and six inches high. Lie back so one end of the support is near your lowest rib and the other supports your head. (If the back of your neck is compressed and your chin sticks up, place a pillow or folded blanket under your head.) Then open your arms out to the sides, about 90 degrees to your torso, and rest them on the floor. Keep your elbows straight to get some biceps stretch along with your chest opening; to increase the pectoralis major stretch, bend your elbows to 90 degrees so that your lower arms rest on the floor alongside your ears. If your upper back rounds, do this pose for a few minutes every day.
To stretch the "lats," the pectoralis minor, and the lower part of the pectoralis major, put your roll (or a block, placed so it's six inches high) the long way across your midback, about the level of your lower breastbone. (Be sure to support your head if your chin juts up.) Stretch your arms up toward the ceiling and then overhead, down toward the floor; lengthen them away from the sides of your ribs to maximize the stretch. (Use a prop to support your hands if your shoulders are painfully tight.) Breathe smoothly and stay in this position for a few minutes, visualizing your "pecs" and lats releasing and lengthening.
If you tend to slump in your upper back, you need to stretch your abductors-the muscles that draw your shoulder blades away from your spine-but also strengthen your scapular adductors, the rhomboids and the trapezius. To do this, practice variations of Salabhasana (Locust Pose). Lie face-down and lift your nose and breastbone a few inches-if you feel some discomfort in your lower back, you're probably lifting too high. With your arms by your sides, lift them and stretch them and your shoulders toward your feet. This strengthens the rhomboids and the lower traps. Next, reach your arms straight out to the sides (or, if that's too difficult, bend your elbows and lightly touch your ears): You'll feel the rhomboids and the entire trapezius working to pull the scapulae toward the spine.
Practice these two variations every other day, gradually holding them longer until you can stay in each position for 30 seconds. Combine this strengthening with the chest-opening stretches, and before you know it you'll be a slumper no more. You'll find your shoulder blades resting in that "just right" place, and you'll be sitting, standing, and practicing yoga with a new freedom and stability in your chest, upper back, and shoulders.
A physical therapist and Iyengar Yoga teacher, Julie Gudmestad runs a physical therapy practice and yoga studio in Portland, Oregon. She regrets that she can't respond to requests for health advice.