Physiology of Yoga

If you make a habit of reading yoga literature, you might have recently come across  articles emphasizing the need to ban the cue “draw the shoulders down the back” when the arms are raised overhead. Acknowledgement that the prompt is problematic is a great first step, but the attrition rate of the action has not seemed to increase. I cringe as I
encounter students day after day still making this self­-adjustment. Witnessing this seemingly unconscious movement is puzzling: the process is completely unnatural, fighting the innate kinesiology of the body. Why, in the absence of any external persuasion, are students electing this modification? While (like most things) several factors are in play, the major offenders are probably three interwoven influences: subsistence of the cue, repetitive conditioning (if you are told something long enough, you start to believe it), and contracture of muscles in the upper back and neck.

The first influence seems the easiest to eradicate… remove this terminology from our vocabulary and our mind. Unfortunately, like a video of an adorable puppy, this cue seemed to “go viral” in the teaching community and ingrained itself as a yoga cliché . If you have investigated this topic before, the following will likely be a review. However, if this is new information, here are the basics of why the action is injurious to the body. The shoulder girdle, arguably one of the most intricate places in the body, contains a varied landscape: ­ bony precipice and plateaus, elastic suspension bridges, deep cartilaginous caverns, shock absorbing water reservoirs, diverging neural power lines, and fast flowing hematologic rivers. While a whole post, even a book, can be dedicated to exploring the intricacies of the shoulder, for our purposes we only need to focus on a few bony landmarks.

The scapula (shoulder blade) and humerus (upper arm bone) meet in the deep cavern of the glenoid fossa and (along with the supporting structures) make up both a ball and socket and hinge joint. Raising the arm overhead requires a host of actions to occur, but here is a stripped down version pertinent to this post. When the humerus begins to rise, it initially moves away from the body (abducting through about 30° of rotation) on its own, until it hits the bony floor of the glenoid cavern. In order for motion to continue upward, the scapula must begin to participate. The lateral edge of the scapula begins to slide upward and tilt posteriorly, allowing the head of the humerus to continue its descent. As the arm continues to rise, this action continues synergistically: for every 2° of lift in the humerus, the scapula rises 1°.

While this demonstrates that the arm and shoulder blade must ascend together, it is not where the problem originates in a yoga class. In fact, lifting your arms from beside your hips to overhead is actually impossible if the shoulder blades are plugged down the back (give it a try, there will be a stopping point where you HAVE to allow the shoulder blade to elevate or your arm to externally rotate). The problem arises when the humerus and scapula have already adjusted to the arm being extended straight overhead. When a student then attempts to “drag the shoulder blades down the back,” the scapula relinquishes its posterior tilt and the bony precipice on the scapula (the coracoid and acromion processes) forcefully push down on the head of the humerus. This results in uncomfortable and detrimental compression, initiating a domino effect that wears away the intricate weave of the shoulder’s innate protective support (bursa, labrum, ligaments, and tendons).

But what if the second factor is still at work (repetitive conditioning) and a student does not want to be told the action they have been “doing forever” (and which has not caused damage…yet…) is wrong? While there are probably a host of different tactics you can use to convince your students otherwise, I believe the best tactic is to give them the straight facts. There is no need for a detailed anatomy lesson in the scope of a sixty to ninety minute class, a simple “drawing the shoulders down the back with the arms overhead creates nasty compression” should suffice. If you want a more kinesthetic proof, try the trick of attempting to lift your arms from a relaxed position by the hips to upright while the shoulder blades remain plugged down.

Let’s say you are convinced the shoulder blades should not be depressed, but you still feel (or see) compression between the ears and shoulders. Truthfully, I believe that this ill-advised cue originated in response to the congestion and apparent loss of space at the base of the neck. Upon first site, it appears that if you plug your shoulders down, the space underneath the ears will expand. Unfortunately, an entire different set of muscles, many of which not even connected to the scapula, are the burglars stealing the space here. A few prime suspects, the splenius capitis and splenius cervicis originate at either the base of the skull or the cervical spine, respectively, and insert on cervical and thoracic vertebrae.

Due to our everyday lifestyles, which require us to jut our chin forward and down (texting, computers, etc) muscles in this region are continually fighting a loosing battle of tug of war against the heavy skull. As the weight of the skull descends, these muscles activate: trying to pull our head back in its upright, neutral position over the spine. To our detriment in this case, the body is intelligent and recognizes these repetitive patterns we have imposed as the ‘new norm.’ Adjusting (or more frightening, evolving… more on that in a later post) to the demands of the environment, these muscles become almost permanently contracted and do not know how to soften.

While this might sound depressingly terminal, there are ways to reverse this action. In some cases, receiving sensory feedback from hands placed on the base of the neck or the crease of the shoulder can help these muscles relax. A second, easy way to create more space in this area is to externally rotate the arms. When the pinky fingers are spun towards the front of the room, there is no choice except for the shelf of the shoulders to broaden.

Finally, you can begin to eliminate this repetitive contraction on your own by learning to realign the head over the spine. However, this realignment is not accomplished by drawing the chin back, as often cued, which will only introduce compression through the front of the throat. Rather,  we can learn to slightly engage muscles such as the digastric and the geniohyoid. Since most of us are unfamiliar with these muscles, a useful cue is to lift up from the corners of the jaw right beneath the ears, almost as if beginning to swallow. This raises the skull from the center (around the hyoid bone) and provides length to the muscles in the back of the neck. Without having to grip onto the heavy weight of the skull, these muscles are given the chance to move away from the ears and take a well deserved rest.

Bringing this back to the bigger picture, how do we reclaim our neck and shoulders? Correct understanding of the body’s landscape provides the soil, while learning to engage and relax in the appropriate manner provide the seeds for change. Once these new patterns start to take root in the body, just a little TLC is required to help encourage this continued, spacious growth, allowing the shoulders and neck to stand tall in celebration of their new found freedom.