You've probably heard a million times that you should externally rotate your shoulders in Adho Mukha Svanasana (Downward-Facing Dog Pose). If you thought that was just your yoga teacher nitpicking, it's time to reconsider. Learning to engage and strengthen the rotator cuff muscles is crucial to preventing common shoulder injuries that plague yogis and non_yogis alike. If you know how to use these muscles the right way, your Down Dogs can help keep your shoulders strong and healthy for a lifetime.
What Is the Rotator Cuff?
The rotator cuff is one of the most important but widely misunderstood structures in the body. It gets damaged often enough that its name has become synonymous with injury. It's a group of four shoulder muscles that surround each shoulder—like a cuff. Boiled down to the essentials, its job is to support and position the ball that forms the head of the upper arm bone and fits in the socket of the shoulder joint. The shoulder is inherently an unstable joint, so building the strength of these supporting muscles is crucial. If they're weak or deconditioned, as is often the case, the shoulder is vulnerable to injury and pain, and the rotator cuff itself may tear.
You can remember the four rotator cuff muscles by the acronym SITS, for subscapularis, infraspinatus, teres minor, and supraspinatus. They all originate on the scapula (shoulder blade) and insert on the humerus (upper arm bone), near the humeral head (the ball that fits in the shoulder joint). The names of three of the muscles give you a clue to their location: subscapularis sits under the scapula, between the ribs and the front surface of the scapula. Supraspinatus sits above and infraspinatus sits below the spine of the scapula. You can feel them with your fingers: Touch one of your collarbones with the fingers of the opposite hand and slide the fingers straight up over the top of the shoulder. Then reach down the back about an inch or two; you'll find a ridge of bone that's more or less parallel to the ground. That is the spine of the scapula, which separates the supraspinatus and infraspinatus on the back surface of the scapula. The teres minor gives you no clues about its name; it just sits on the outer edge of the scapula, near the posterior fold of the armpit.
Shoulder Anatomy 101
While all four muscles work in concert to stabilize the shoulder, each muscle also helps support the shoulder individually. The subscapularis is a powerful internal rotator. Supraspinatus helps hold the ball up in its socket against the downward pull of gravity on the arm, and it initiates abduction, or lifting the arm up from your side, as in Virabhadrasana II (Warrior Pose II). Teres minor and infraspinatus are the primary muscles that control the external rotation of the shoulder. When they're strong and healthy, they help to protect the shoulder joint by positioning the ball in the socket while you raise your arm overhead. Conversely, their weakness can contribute to common shoulder problems such as shoulder impingement, tendinitis, and bursitis.
These important external rotators, infraspinatus and T. minor, are the part of the rotator cuff that is strengthened in Downward Dog. It's a good thing, too, because these days, the laborsaving products and devices we use make our arms and shoulders progressively weaker as the decades slip by. A weakened rotator cuff might lead to abnormal shoulder-movement patterns, which can contribute to inflammation and pain. Not only that, but weak muscles are likely to tear when you put a load on them that they aren't strong enough to handle. Sometimes the tears are microscopic and will heal on their own. But if the tears are bigger, a surgeon may have to sew the separated ends of the torn tissues together. Repairing a torn rotator cuff surgically, though, isn't a given: One doctor described the repair process as being like trying to sew up a run in a nylon stocking. The tissues of the atrophied muscles and their weakened tendons are just plain flimsy—liable to tear and difficult to repair.
So, a word to the wise: It's much easier to work your rotator cuff muscles, make them strong, and keep the tissues healthy than to have to see a physical therapist like me for shoulder treatment and rehabilitation or, worse still, to have to visit a surgeon. And it's in this way that your daily Downward Dog practice will really pay off—if, that is, you know how to engage infraspinatus and teres minor.
How to Externally Rotate Your Shoulders
Properly engaging the external rotators takes some training. In fact, many students unknowingly let their shoulders slip into internal rotation in Downward Dog, leaving the external rotators lazy and inactive.
To get a feel for engaging the shoulder external rotators, stand facing a dining table or desk. Lean forward and place your hands on it, palms down and bearing a little weight. Now look at your elbows, noticing the crease on the inner sides and the point of the elbows on the outer sides. When you rotate your arms so that the elbow creases point forward, you will be externally rotating your shoulders. When you rotate in the opposite direction and the points of the elbows poke out to the sides, you will be internally rotating your shoulders. Play with this a bit by rotating in and out with this light amount of weight bearing, and you may even be able to feel the teres minor and infraspinatus contracting across the back of the shoulders as you turn the elbow creases forward.
Now go to your mat and do Down Dog. If you're a newer student or have tight shoulders, you may notice that they tend toward internal rotation, with the elbows sticking out to the sides and maybe even bent. Still in Dog, come forward a few inches toward Plank Pose and actively rotate the elbow creases relatively forward, so that they point toward your thumbs. Move back into Dog and try to keep some of this external rotation, though you'll have to give some of it up to fully open the shoulders. Maintaining some external rotation will keep the teres minor and infraspinatus contracting, and you'll probably notice more space opening up between your shoulder blades.
Once you've mastered keeping the external rotators engaged in Downward Dog, you can apply the action to more challenging poses such as Urdhva Mukha Svanasana (Upward-Facing Dog Pose) and Chaturanga Dandasana (Four-Limbed Staff Pose). From Downward Dog, come forward into Plank Pose. Rotate the creases of your elbows forward and hold your elbows against your sides as you let down to Chaturanga, then glide forward into Upward-Facing Dog. As you actively turn your elbow creases forward in this pose, the external rotators will be contracting strongly, and you should notice that this action broadens and lifts your chest.
Now notice how this shoulder rotation affects the weight placement in your hands. If the shoulders internally rotate, more weight tends to fall onto the inner side of the hand—that is, the thumb and index finger; in external rotation, the weight falls more onto the little-finger side. Ideally, your weight should be evenly balanced between your inner and outer hand, so that as you externally rotate at the shoulder, you'll need to focus on actively pressing down on the base of the index finger and thumb. This action of the forearm and hand is called pronation.
Typically, pronation of the forearm and hand occurs when the arms are internally rotated. For example, as I sit at my keyboard right now, palms down, my elbow points are sticking out to the side, which shows how pronation is linked with internal rotation. But Downward and Upward Dog require us to break our usual patterns by linking active shoulder external rotation with pronation of the hand. As you practice connecting these opposites, perhaps you'll appreciate anew how yoga helps you to break your old, unconscious habits in every aspect of life—and replace them with healthy, conscious, and considered ways of living.
Julie Gudmestad is a physical therapist and Iyengar Yoga teacher in Portland, Oregon.