Most know that the diaphragm is essential for breathing, and breathing is essential for life. Proper use of the diaphragm is essential for proper stability of the low back and should be included in low back pain rehabilitation.   But few actually use their diaphragm to its full capabilities.

The diaphragm serves 3 functions:

1)    Respiration

2)    Stabilization

3)    Lower Esophageal Sphincter    



The diaphragm is the major muscle responsible for normal tidal breathing. In proper respiration when we take a breath in the diaphragm is pulled downward by a central tendon. The diaphragm contracts concentrically and flattens as it shortens and we take in air. With expiration the diaphragm goes up and returns to its normal domed shape.   As the diaphragm drops during inspiration, if the position of the diaphragm is directly over the pelvic floor, the diaphragm creates an outward pressure into the entire abdominal wall and back, as well as the pelvic floor. This eccentrically loads the abdominal wall and pelvic floor and creates tension into the back in order to stabilize the spine.   This pressure created into the entire abdominal wall is the only thing we have to stabilize the front of our spine. There is no muscle that attaches to the front of the spine that can oppose the spinal erectors. So, it is crucial that we create the right breathing mechanics to properly stabilize our spine.  

Stabilization (more on this in a later post):   

The regulation of what is known as intra-abdominal pressure (IAP) is also a job of the diaphragm. When we go to move, bend over, lift an object, or perform any other movement there needs to be stabilization of the spine first. Although the mechanics of creating intra-abdominal pressure and breathing appear to be the same, there are some differences. The diaphragm still has to drop and there needs to be a  load into the entire abdominal wall, but what happens with abdominal wall and pelvic floor are different. They don’t simply eccentrically lengthen but isometrically stiffen to regulate the pressure in the abdomen.   As the diaphragm is pulled down the abdominal wall stiffens to create pressure inside the abdominal wall. For a simple task (bending over to tie a shoe) there needs to be minimal IAP; the abdominal wall stiffens minimally and pressure is created through the entire abdominal wall. When something requires more IAP (lifting a heavy weight, pushing a heavy door) the abdominal wall stiffens more. As the abdominal wall stiffens, the diaphragm is pushed down harder, which in turn stiffens the abdominal wall more. These two opposing forces (the diaphragm and stiffening of the abdominal wall) increases IAP.    


Lower Esophageal Sphincter:   

Part of the stomach makes its way through the diaphragm. As the diaphragm drops it is supposed to close the lower esophageal opening and not allow any contents to come back through the esophagus from the stomach.   In those with acid reflux, or GERD, we can see an inability to use the diaphragm properly to close down the esophagus.

Ryan Crandall

Ryan Crandall

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