Movement of the spine- part I

“Men are born soft and supple; 
dead, they are stiff and hard. 
Plants are born tender and pliant; 
dead, they are brittle and dry.

Thus whoever is stiff and inflexible
is a disciple of death.
Whoever is soft and yielding
is a disciple of life.

The hard and stiff will be broken.
The soft and supple will prevail.”
~Tao Ching

“If your spine is inflexibly stiff at 30, you are old.
If it is completely flexible at 60, you are young.” 
~Joseph H. Pilates

   This is part I in an exploration about spines, or your back, or the part of yourself that you can’t see but you rely on to play a significant role in allowing you to move. This area is the source of many differing beliefs among experts, practitioners, and people that work with bodies. Below is the story of how my exploration of movement, working with clients of all ages and abilities, and research have informed my opinion of the back and how it works in an exercise and movement setting. 
    The spine is also an area that will likely cause the average person discomfort at some point. The World Health Organization’s position statement estimates 60-70 percent of adults living in industrialized countries will experience low back pain at some point. (They also claim that as the world population ages, we are all doomed because of disk degeneration. However, as I pointed out in my blog on nociception, disk degeneration is not necessarily predictive of pain, as noted in the systematic review by Brinjicki, et al., 2014). Low back pain accounts for 3.15% of all emergency visits, with 65% of the injuries occurring at home (Waterman, 2012). A large scale study performed by the National Health Interview Survey found 9 million US residents suffered from neck pain and 19 million suffered from both neck and low back pain during a 3 month period in 2002 (Strine and Hootman, 2002). These numbers are large, and often lead to statements like, “my back goes out,” or “I have a bad back.” This can turn into a vicious pain cycle involving fear of movement and/or the underlying notion that exercise is painful. The Center of Disease Control estimates 49.2% of Americans are getting adequate amounts of cardiovascular activity, while only 20.8% of Americans meet the recommendations for aerobic and strength based exercise (3). Perhaps more alarming are the results of a survey done in 2012, indicating one in four young adults (12-15) meet the recommended amount of moderate-vigorous exercise, 60 minutes a day (Fakhouri, et.al, 2012). The point is, exercise and movement should be encouraged; this becomes difficult when things hurt.
    On the other end of the spectrum are the amount of physically active adults (and fitness professionals) that have episodes of low back pain they don’t report. I was unable to find any data on the topic, but I read enough and go to enough workshops to know there are a surprising number of “fit” individuals that teach/train experiencing discomfort somewhat regularly. This brings me to the conclusion that a) the spine is complicated and b) many people feel better with a novel stimulus. Too much of one thing/direction/movement might not serve us as well (and how many trainers, myself included, are guilty of using our exercise sessions to work on the the three things we like? Over, and over, and over again, while ignoring the things we don’t like, which are probably the things we should be doing).
    How is the spine designed to work? This depends on who you ask. Pilates, whose words I used above to demonstrate the importance of a supple spine said about posture in his book, “Your Health,” “What really is desired, is not the backward throw of the shoulders as previously indicated, but rather the simultaneous drawing in of the stomach and the throwing out of the chest,” (Pilates, 1934). This is the beginning of what many term, “abdominal hollowing.” (And if someone can successfully throw out the chest and draw in the stomach while still performing efficient movement, I applaud you. When I tried this after reading it, I felt like the tin man). Stuart McGill, in his book, “Low Back Disorders,” who advocates teaching abdominal bracing in the presence of low back pain, states “stiffness is required in every rotation and translation axis to eliminate the possibility of unstable behavior,” and points to repeated flexion as a possible cause of disc herniation (McGill, 2007). “Low Back Disorders” was one of the first textbooks I read on the spine. After reading it, I became petrified I was ruining people’s backs with the exercise programs I was designing. This led to my programming consisting of no spinal flexion, extension, or rotation, lots of glute exercises, and instructing people to “keep their abdominals braced at 20% most of the time.” I cringe when I think about it, and am extremely grateful this was a small blip across my learning spectrum (thank you, graduate school). In retrospect, I realize I took things out of context and my fear (and there was deep fear, because the last thing I wanted was to injure people), was perhaps a bit misdirected.
    During graduate school, I was introduced to Dynamic Neuromuscular Stabilization (DNS). DNS discusses breathing and transverse abdominis activation using the inhale to provide spinal stability. Intra abdominal pressure (IAP) is believed to increase stability and stiffness of the spine; stimulating the diaphragm was shown to increase IAP  as much as 61% during maximal voluntary pressure and as much as 31% at rest (Hodges, et.al, 2005). Suddenly, the diaphragm’s position was important, the ribs mattered a tiny bit, and rotation was important for neuro-motor control and vestibular awareness. I liked where this was going. “Ribs down,” became my favorite cue, and I was fairly certain I could solve the world’s problems by decreasing neck activity during breathing. 
    This was a step in the right direction, but I still struggled with how yoga fit into all of this. I had studied yoga for quite a while, it had helped me, and there was a lot of extension. I kept hearing extension was “bad.” If it was bad, why was it even an option? 
    Enter PRI and gait mechanics, which allowed me to finally get a (small) handle on how the breath actually worked, as well as the importance of position. Not only does an expiratory rib position during a resting state matter, the ribs should be flexible during breathing and are attached to vertebrae designed to rotate. The pelvis position during rest also matters, since the pelvis is connected to the sacrum, which absorbs force, and connects to the lumbar vertebrae, which are designed to flex and extend (Earls, 2014). If someone has a lumbar spine that is stuck in extension, for instance, this is akin to an ankle that doesn’t know how to dorsiflex during gait, Movement will be compromised. This, of course, begins to make a lot of sense when you consider we do not behave symmetrically when we walk. During heel strike on the right side, for instance, the left hemi-pelvis tilts to the left and goes into flexion, while on the right moves into extension (Earls, 2014). This allows force to be absorbed up the spine, and the body counterrotates with the right arm swinging forward while the left leg swings forward. There is much more happening that I am not going to delve into, but the basic gist of it is the spine moves in a variety of ways when we walk to accommodate force. 
    What does this have to do with rib position? During inhalation, the diaphragm moves down and the ribs move up and out (Novotny & Kravitz). During exhalation, the diaphragm moves up, while the ribs move down and in. Consider that the ribs are attached to the thoracic vertebrae and the ribs can expand both in the front, to the side, and the back. The ribs move, and due to their attachment points with the thoracic vertebrae and (for ribs 2-7) their attachment with the sternum via the costovertebral and costosternal joints, they are influenced by breath and impact movement of the thoracic spine (van der El, 2010). Quite simply, how we breathe affects mobility at the ribs, which affects how our thoracic vertebrae move, and if the job of our thoracic vertebrae is to accommodate force from the lumbar vertebrae and rotate to allow for arm swing, rib position matters. 
    I keep discussing this idea that force is absorbed as we move. What happens if it isn’t absorbed in a uniform way? An interesting abstract published in the journal “Gait” examined how posture changes when visual input is removed (because our body is an integrated system, and the eyes are part of that system. They have a very definite impact on posture and position). What the researchers found was when subjects were blindfolded, individuals with non specific low back pain (NSLBP) had larger deviations in position of the thoracic and lumbar spine than the control group (Schelldorfer, et al, 2015). Our spines are designed to move in a variety of different ways to allow us to stay upright. Moving sideways (in the frontal plane), is one way we can accommodate upright posture. Imagine a Jenga tower that begins to sway to the side because of the way the pieces are removed down below. The only way for it to stay upright is to change it’s balance point. This is sort of what’s happening in the individuals with NSLBP in this study. Their brains don’t know how to use the stability of the vertebrae in an organized way to stay upright, and so concessions are made above and beyond what occurs in someone that is asymptomatic. Why this happens would be speculation on my part, and is probably best saved for someone that knows more about the topic than I.
    So in addition to the pelvis and the ribs, if the eyes provide feedback to our vestibular system regarding where we are located in space, we can assume head position affects spine mechanics as well, since the eyes are located in front of the head, and the head is connected the cervical spine. Studies suggest eye movements are affected by neck, torso, and foot proprioception, and it appears the brain relies heavily on information from the feet and the eyes to determine posture (Foisy, et.al, 2015). This suggests how we move and what we experience isn’t determined by just one factor (and I promised myself I would refrain from discussing the psychological aspect of how we move and interact with the physical world, but suffice to say, there are other things at play). 
    It is obvious to me (and hopefully you can see my rationale) the vertebrae of the spine move, in a variety of ways. The way the spine moves is determined by a variety of factors, including the idea of biotensegrity. Biotensegrity is based on the idea that bones, muscles, and connective tissue work together as a functional unit. Bones move around shape shifting, complex helical axes (Scarr, 2014). What this means from a biological perspective is that because our whole entire system, from the cells, the muscles, the connective tissue (including fascia), and the bones are all intertwined, stress imposed, say, in the cervical vertebrae will likely influence a structure somewhere else in the body. The imbalances these stresses create are managed through the attraction and repulsion between atoms; problems occur when these stresses are persistent. From a movement perspective, most of us understand the body is never truly still. Even the act of breathing causes little changes to occur throughout the spine to accommodate the increased volume of air as we inhale and the emptying of the air as we exhale. (As I mentioned earlier, our ribs are flexible to allow for this natural act to take place). This, again, resembles life. Stress isn’t bad; the inability to recover from stress, on the other hand, becomes problematic. 
    Once I realized this, I also concluded backbends were not going to cause massive back problems if the forces were evenly distributed through the entire structure, including the hands, shoulders, feet, hips, and throughout the spine and the people practicing backbends were also able to remove the stress once the backbend was finished. Whether or not this happens depends on the resting position of the ribs and the pelvis (if your resting position includes lumbar vertebrae that lack mobility because they are in a more extended position, your ribs will also be lifted away from the pelvis, putting your shoulders and hips at a disadvantage because of the whole tensegrity thing. If the goal is to distribute force evenly, and one of the segments in the chain can’t move to allow for that force distribution, the imposed stress of the action will never be removed). A mobile spine is not a bad thing as long as you have a sense of stability to return to. 
     I will discuss this more in part II, which will cover practical application of the topics explored above. In our effort to make the complex understandable, it is easy to get lost looking too hard at minute details.  If instead we explore a bigger goal of maximizing load distribution and efficiency in various movements, it becomes easier to recognize the interconnectedness that is the human body. Being strong matters, but so does being supple. One isn’t better than the other, and human nature dictates most people will favor either strength or suppleness. Life also happens; the amount of stability and suppleness a person can attain might be limited by structural issues, surgeries, and previous trauma or accidents. All we can do is work towards a sense of balance in our attempt to move well, pain free.  

Yours in health and wellness,
Jenn

References: 
Brinjikji, P.H., Luetmer, B., Comstock, B.W., Brenahan, L.E., Chen, R.A., Deyo, S., Halabi, J.A., Turner, A.L., Avins, K., James, J.T., Wald, Kallmes, D.F., & Jarvik, J.G., (2014). Systematic literature review of imaging features of spinal degeneration in asymptomatic patient. American Journal of Neuroradiology, doi: 10.3174/ajnr.A4173
Waterman, B.R., Belmont, P.J., & Schoenfeld, A.J., (2012). Low back pain in the United States: incidence and risk factors in the emergency room setting. Spine Journal, 12(1), 63-70. 
Strine, T.W., & Hootmant, J.M., (2007). U.S. national prevalence and correlates of low back and neck pain among adults. Arthritis and Rheumatism, 57, 656-665.
http://www.cdc.gov/nchs/fastats/exercise.htm
Fakhouri, T.H., Hughes, J.P., Burt, V.L., Song, M., Fulton, J.E., & Ogden, C.L., (2014). Physical activity in U.S. youth aged 12-15 years, 2012. NCHS Data Brief, 141, 1-8. 
Pilates, J.H., (1934). Your Health. Presentation Dynamics Inc. 
McGill, S., (2007). Low Back Disorders. Human Kinetics: Champagne, Illinois.
Hodges, P.W., Eriksson, A.E., Shirley, D., & Gandevia, S.C., (2005). Journal of Biomechanics, 38(9), 1873-1880. 
Earls, J., (2014). Born to Walk. North Atlantic Books: Berkeley, CA. 
Novotny, S., & Kravitz, L. The science of breathing. https://www.unm.edu/~lkravitz/Article%20folder/Breathing.html
http://www.who.int/medicines/areas/priority_medicines/Ch6_24LBP.pdf
van der El, A., (2010). Orthopaedic Manual Therapy Diagnosis. Jones & Bartlett Learning: Burlington, MA.
Schelldorfer, S., Ernst, M.J., Rast, F.M., Bauer, C.M., Meichtry, A., & Kool, J., (2015). Low back pain and postural control, effects of task difficulty on centre of pressure in spinal kinematics. Gait, 41(1), 112-118. 
Foisy, A., Gaertner, C., Matheron, E., & Kapoula, Z., (2015). Controlling posture and vergence eye movements in quiet stance: effects of thin plantar inserts. PLoS One, 10(12).
Scarr, G., (2014). Biotensegrity. The Structural Basis of Life. Handspring Publishing: Scotland.