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How a Physical Therapist Defines "the core"

Updated: Dec 13, 2022

When someone says "You need to strengthen your core" to help with low back pain what do you think of?


Do you imagine doing hundreds of sit-ups and crunches trying to get as close to a 6-pack as humanly possible?


Well, when physical therapists reference strengthening the core as part of a rehab plan, 6-pack abs are far from our mind...


What is your core?

In our heads, the core consists of four muscle groups vital for maintaining overall musculoskeletal health.

1. Transverse abdominus

So, your abs are part of your core... Just not the 6-pack ones!

The transverse abdominus is the deep layer of the abdominal muscles and it wraps your entire lower torse sort. This muscle along with the multifidus muscles (multifidi for plural) act as a corset for support.


2. Multifidus

One of the deepest layers of muscle attaching to the spine. Its function is to stabilize the spine when performing larger, big movement, functional tasks such as almost any movement you can imagine...


3. Diaphragm

The diaphragm is the main muscle of inspiration meaning it is in charge of drawing air into your lungs. Its secondary function is stabilizing the lumbar spine!


4. Pelvic Floor

Pelvic floor consists of a hammock of muscles making up the lower aspect of our "core". They not only help stabilize the spine and pelvis, but also support reproductive/urinary/bowel internal organs, allow for health sexual function as well as control sphincters in charge of urine/bowels/gas.

How do they work together?

Picture a soda can (or beer or an energy drink... whatever).


It's full. Never opened.


Now imagine trying crush the soda can by squeezing it in your hand. You probably can't do it right? It's strong. It's pressurized!


But what happens when you pop the top to that soda can?



The pressure is released and now if you wanted to, you could easily squeeze and crush the soda can. You'll make a mess, but you can do it.


Now imagine this analogy. Your "core" is like a soda can.


The top and bottom or the diaphragm and pelvic floor respectively. The sides are your multifidi and traverse abdominus.


Our spine is strongest when we increase our intra-abdominal pressure. This is why we feel the need to "bear down" and perform what's called the Valsalva Maneuver and hold our breath when we attempt to lift something heavy. We're increasing pressure to stabilize the system under an expected heavy load.


When you breath, it as if you popped the top to the can. Your diaphragm is allowing the top of the can to open.

When we breathe in, our diaphragm contracts then descends downward into the abdominal cavity (This is what causes your belly to move outward when your inhale). Then as you exhale, the diaphragm moves upward returning to its starting position.

The diaphragm and the pelvic floor work together; as one descends so does the other which creates stability of the system.


If one part of this soda can system isn't doing to duty well, the pressure goes to a weak point i.e., a disc herniation, or an umbilical hernia, or make your diastasis recti worse, or influence hip pain or lead to dysfunction of any of its parts such as pelvic floor issues leading to incontinence. A multitude of issue may arise when the soda can is not as strong as you need it to be!


If you feel you don't have quality core control as we've described it above, then it may be contributing to your recurrent issues that led you to reading this blog in the first place! Give us a call to identify your specific imbalances and begin a path toward recovery.

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