Part I: What is the Core and Why is it Important?

Why is the core important?  This is a question that has come up quite a bit in the last 20ish years.  Core stability continually has been the thing that supposedly everyone needs.  Back pain?  Strengthen the core.  Leg pain?  Your core is probably weak… so you should strengthen it.  Hip pain?  The core is probably involved.  Foot pain?  Look back up to the core.  Shoulder pain?  Definitely core weakness.   Elbow pain?  Probably something to do with the core. 

This is what I hear and have had thrown at me as a physical therapy student not only by professors, teachers and more but from research, continuing education courses, movement gurus and more.

But my question is….. why are we focusing on this area of the body?  What is the core?  Why is it important?  Is it important?
Apparently we’re supposed to stabilize the core.  A “stable” core is important because you need a stable base to move your limbs on.  If the base is unstable, you lose a great amount of the force and the base can break down from inappropriate attention of forces.  So in the case of the human body, we’ve been told you want a stable core so you can throw harder, run faster, lift heavier and jump higher.  As I’ve heard many times, “You wouldn’t want to fire a cannon from a canoe.”  Thinking about that phrase deeply confuses me.  Why would you do that in the first place?  Get a bigger boat or put the cannon on land.  Only an idiot would do that.  Also you can’t strengthen a canoe.  I think this is a stupid analogy and we should get rid of it.  Mostly because I overanalyze things like that.  Which also happens to be why I’m writing this.

So what is the core?  It’s not just the abdominals.  The abdominal musculature, including the rectus abdominis, internal obliques, external obliques and transverse abdominis (and some would argue the pyramidalis) make up part of the front of the core.  PART.  Not the whole thing.  I generally think of the core as the trunk of the body.  That includes the spine (sacral, lumbar, thoracic and a bit of cervical), pelvis, hips, scapulae (shoulder blades) and shoulder.  

So anteriorly, you have the abdominal muscles I mentioned in addition to your deep muscles that attach and the pelvis.  That includes the transverse abdominis, but also the iliacus and psoas.  Yes I consider those core muscles.  In most people, those muscles are tight and we’ve been taught to stretch those muscles and stretch them so more after.  Don’t you want to have appropriately lengthened and strengthened muscles?  More on that later.

Posteriorly we have the erector spinae (big back muscles running up and down the back), multifidi, latissimus dorsi, all three parts of the trapezius (lower, middle and upper), intercostal muscles of the ribs (which are also part of the lateral and anterior portions) and more small back muscles that I am forgetting right now. 
Laterally we again have the internal and external obliques, erector spinae (one sided this time) gluteus medius, minimus, maximus, the tensor fascae latae, a bit of the transverse abdominis and the external rotator groups (including the piriformis). 

Inferiorly… yes I said inferiorly, we have the pelvic floor muscles.  Few people talk about these because no one wants to talk about sex, peeing and popping.  But this muscle group, the levator ani, have some of the best leverage to stabilize the pelvis.  How awesome is it that they can stabilize from the inside??   I would argue these are as important as any other muscle group in the core.

Superiorly… yes I’m going into places people don’t usually talk about, we have the diaphragm.  This massive muscle that’s really important for breathing that few people address.  Breathing is pretty important, which also makes this muscle important.  You can also argue that superiorly we have the rotator cuff musculature of the scapulae, the serratus anterior, the serratus posterior (superior and inferior… which I know some people argue are next to useless) the pecs (minor and major), intercostal muscles of the ribs and more.  I think the diaphragm and scapular musculature especially are equally important as the other core muscles!

So now you understand why when I say someone with six-pack abs does not necessarily have a good core.  In fact, in my mind, they may have a poor one.  Why?  Because the six-pack muscle, the rectus abdominis, is an external muscle that is usually overdeveloped in those who do too many sit-ups, crunches, etc.  It typically one of the larger muscles that compensates for weakness in the smaller muscles that actually have better leverage to provide stability.  It does not have the same leverage as the Transverse Abdominis, which is the deepest abdominal muscle that has attachments to the spine, ribs and pelvis.  Not just the ribs and pelvis like the rectus abdominis.  The rectus is a trunk flexor.  The fiber orientation is not condusive to handling forces in the diagonal, frontal or transverse planes.  Just one plane of motion… the sagittal plane.  Which is fine, but true movement is never in one plane.  A motion as simple as reaching out in front of you involves multiple muscles and joints moving through and in the diagonal, transverse, frontal and sagittal planes.  So is the transverse abdominis, the deepest core muscle, the holy grail of core stability?  No. 

That’s right I said no.  In physical therapy, everyone seems to be focused on the transverse abdominis.  It’s the deepest core muscle.  I do think it is an important muscle given that it wraps the core anteriorly, laterally and posteriorly.  Research has linked back-pain to poor motor control and firing of this muscle.  It must be the most important right? 

Oh wait… didn’t I say that the abdominals are only part of the core?  Yes.  The human body is never that simple.  Didn’t I just describe the many muscles that make up the core?  Yep.  It’s never about one muscle or even one muscle group.  The human body does not use one muscle at a time.  It uses entire groups of muscles and kinematic chains for optimum production and transmission of forces across many joints. 

So thus far the core stabilization techniques I’ve been taught and have been exposed to have all focused on locking down that set of muscles.  “Your core should be stable.”  “The core shouldn’t move.”  “Think of the canoe.”  This is what I hear. 

Doesn’t that make sense though?  The canoe analogy?  You want a stable base right?
Yes and no.   I think we’re approaching the idea of core stability inappropriately.  Why would I say that?  Doesn’t that go partially against everything we’ve learned?  Everything we’ve been teaching and treating our patients with?  Is it possible we’ve only gotten half of the equation? 

I think so.

Part II is on the way.....

Thanks for reading!

-Matt Klein, SPT