Written by: Jeffrey Sergent, DC
This is a debated topic. A fun nerd-fight if you will? I find the difficult part is really defining the core. Many different groups and clinicians have different muscle groups associated with their definition of the core. But I suppose I will define my own opinion of the groups of muscles that define core and why.
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| Outer core muscle examples |
The deeper or inner core muscles create the top and bottom of that can. This would be the diaphragm, pelvic floor, multifidus, longus colli and longus capitis (deep neck flexors). I do include neck muscles, dnf, in the core. My reason for this is basically that the spine works as a unit. If the neck is too far out of alignment, then the lower back will be too. To see what I mean try to do this easy exhale technique on yourself: Place your hands on your low back and now protrude, or jut your neck and chin forward. Feel how the lower back follows, resulting in increased muscle activation down there.
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| Deeper/Inner core muscles |
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| Deeper/Inner core muscles in the neck. |
The reason for the distinction of inner and outer core is in the development of performance and rehab. The goal is to be able to create a brace and muscle stiffness that don’t allow the spine to move. This stiffness protects the spine from mechanical stress during lifting, bending, sitting, standing... pretty much everything. If there is inefficiency in the core, then the energy will be displaced from the muscle and stiffness to the only still structure: the spine.
Really the purpose of the core is to create intra abdominal pressure and stiffness. Let's go back to the can analogy. If you had only the outer shell, no top or bottom, you would be able to deform it without much effort. Now add a lid and bottom, the inner core. This creates more rigidity and stiffness, making you put in a little more effort to crush that can. Now imagine increasing the pressure within by carbonating and shaking up the can. This creates an even greater stiffness. At this point that can would be pretty difficult to deform, and unless someone gets thirsty would last quite a bit longer than any of the individual parts of the can on their own.
Photo sources: www.slamdunk.ru, mikescottdpt.com, www.cityedgephysio.com.au
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Dr. Jeffrey Sergent is a certified Clinical Rehab Specialist and Chiropractor. He earned his Bachelor's Degree in 2004 from Michigan State University and his Doctorate Degree from the National University of Health Sciences in 2008. His special interests include Trigger Point Therapy, the Functional Movement System, Developmental Kinesiology, Pain Neuroscience and nutrition for chronic pain. Currently he practices at Goodyear Chiropractic Health Center in Milwaukee, Wisconsin.
