Understanding core stability in the context of ideal posture, and the importance of intra-abdominal pressure working in concert with eccentric diaphragmatic control

When we meet a fact  which contradicts a prevailing theory, we must accept the fact and abandon the theory, even when the theory is supported by great names and generally accepted.

Claude Bernard (Father of modern scientific method who did the preliminary work on the basis for understanding ‘homeostasis’.  Homeostasis functions through multiple dynamic equilibrium adjustments using regulation mechanisms.)

My friend Nic and I went to see a mutual old friend a couple of weeks ago.  We went to visit Yik Ming Chim, affectionately known in Australia as Jim.  Jim is one of the truly great treatment and exercise based practitioners.  He is a physiotherapist by training, and his way of working has evolved as a result of the questions he has had, and the people he has trained with who have allowed him to approach answering those questions through observation, treatment and self-experimentation.

Jim is amongst the best I have seen at being able to see the invisible.  That is; he is able to understand what is going on in an individual’s living posture by all the nuances being evidenced in simple standing and moving.  He was one of the pioneers in photographic assessment of posture from a pre/post perspective and as part of this service you would receive an individuated program based on your postural presentation.  Jim and I worked together in the AIS tennis program for 7 years and we were able to go a long way toward keeping the athletes injury free while also showing significant improvements in fitness parameters as a result of an approach focused on muscle balance and movement efficiency.

Jim did some work on Nic based on his spine from years of working on his set up required in golf.  Nic has worked hard on gaining symmetry and balance after a long period of working on golf during his teenage years. When it was time to focus on the exercises, Jim had Nic perform a supine and prone posture with an emphasis on increasing intra-abdominal pressure while challenging spinal stability from a developmental perspective.  The principle underpinning this approach is understanding the importance of the diaphragm in deep system stabilisation, because of the link between breathing and stability.

This educational/treatment approach that has originated out of the Prague School emphasises the training of ideal patterns as defined by developmental kinesiology, that is; the stabilisation developmental pattern of a healthy baby during the first year of human life.  The ultimate goal is to teach the brain to maintain central control and stability of the movement through the use of reflex stimulation, feedback and understanding the principles of the exercises.  Activation of the stabilisers while in the primal developmental postures is key to automating the patterns.

Physiologically the diaphragm performs a dual function of respiration and postural stabilisation.  Breathing involves the travel of the diaphragm during a three-dimensional shape change in the thoracic and abdominal cavities.  Postural stabilisation requires the coordination of all muscles stabilising the segments of the spine against gravity and any external forces.

The head, neck and shoulders are stabilised via balanced activity between deep neck flexors and spinal extensors of the cervical and upper thoracic regions.

Stability of the lower thoracic and lumbar region is dependent upon the proportional activity of the diaphragm, pelvic floor, all sections of the abdominal wall and spinal extensors.  Postural insufficiency of a single muscle within this group will compromise the entire stabilisation chain, resulting in muscular dysfunction, trigger points and postural instability.

Intra-abdominal pressure (IAP) is generated and maintained by the diaphragm working with trunk and abdominal muscles to create internal positive pressure, which in turn creates functional strength and contributes to stability.  A good example of this type of strength and stability are well trained Sumo Wrestlers.  Consider for a moment, the very best Sumo wrestlers that you have seen.  They sit in a deep squat with abducted thighs with no deviation in their spinal length or sense of strain in their composure.  They also have the ability to explode out of this deep position dynamically.  You will have noticed that they are not tightening or hollowing their abdominal wall muscles to achieve this feat.  Intra-abdominal regulators are the thoracic diaphragm, abdominal and pelvic floor muscles.

The contraction and subsequent flattening of the diaphragm needs to be able to happen independently of breathing in order to maintain intra-abdominal pressure.  What this means is that you can still breathe and have the diaphragm return the lungs on an exhalation, while maintaining an increase in IAP.  The ability that needs to be trained is to maintain an expanded abdominal cavity while the diaphragm works eccentrically on an exhalation.  The increase in IAP can be modulated dependent on practice and the stability required by the task.

From a functional and biomechanical perspective a horizontal diaphragm position is necessary for the diaphragm to flatten and to have abdominal muscles support its activity eccentrically or isometrically.  For ideal stabilisation and respiration the chest position must be aligned above the pelvis with their axes close to horizontal and parallel to each other.  This principle links with Janda’s view of the dysfunction that arises in the upper and lower crossed syndromes of the shoulder and pelvic girdles respectively, with muscle imbalance.

The position of the shoulder blades is another key factor in stabilisation.  The medial borders of the scapulae should be parallel with the spine, with the inferior angle fixated on the rib wall.   The instruction for the shoulder blades to be ‘back and down’ is almost universal in yoga and Pilates classes, however this practice raises the physiological centre of mass forwards and upwards, while hollowing the low back.  Stabilising activity of the serratus anterior is dependant upon the position of the chest and shoulderblades with the overall length of the spine and involves coordination between diaphragm and abdominal muscles which act as a fixed point for serratus anterior activation.

This way of working is very challenging from the point of view of attending to breathing and posture, but also very rewarding.  It is very satisfying when body, mind, breath and attention are integrated in the task.

If reading this blog has stimulated you to find out more, or to consider learning to move, exercise and play sport with this knowledge, please read the services page for more information or follow up with an email or a call.


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