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Do we REALLY have a "CORE"? - Whatever is "our CORE"? - What does it REALLY mean to have a "CORE"

Updated: Sep 19, 2023

In common, daily communication with clients and patients, this word is central to their inquiries. They always want to know:

  • "What is my "core"?

  • "How do I engage my core?"

  • "I don't know how to connect to my core."

  • "I know I am supposed to use my core - but what does that mean?"

  • "I have weak core muscles."

  • "Are my core muscles the same muscles as my pelvic floor muscles?"

  • Can you help me get to my core muscles?"

  • "I've never been able to understand my core muscles - what are they?"

  • "I cannot feel if I am using my core"

When they ask these questions, here is my response: "Humans don't have cores......apples, pineapples, pears, planets, and nuclear reactors have "cores".... (and/or some variation of the listing of items given).


If you look up the word "CORE", in any given English dictionary, you'll find similar definitions, of which there are several definitions for the this word. Some common ones from the following English dictionaries are (the below dictionaries are the ones I didn't have to buy but could access online):

  • American Heritage Dictionary: "core": "(13.) (relative to Anatomy): The muscles in the trunk (emphasis added) of the human body, including those of the abdomen and chest, that stabilize the spine, pelvis, and shoulders.

  • Merriam-Webster: the muscles of the mid-region of the torso

  • The Chambers Dictionary: no anatomical reference

  • The Collins Dictionary: (2). a countable noun; The core of an object, building, or city is the central part of it.......i.e. the Earth's core

What strikes me first is that these dictionaries use "trunk", "torso", and "object" to give some idea or construct for the reader to grasp. So, let me address each one of these words and my concerns with using a word to define another word

  1. The Chambers Dictionary: does NOT even have an anatomical reference so that the word can be applied and used. So maybe humans don't have "CORE"s?

  2. American Heritage Dictionar: with regards to the reference of anatomy, uses the word "trunk" to define "CORE". Then I ask myself - what is a trunk. A trunk can belong to an elephant but it can also label a piece of furniture or luggage. We could also say a tree has a "trunk". In all of these examples of a "trunk", one understands it to be an object, an appendage, or a piece of something else. Humans - too - have a "trunk". It is the section of the body that is between the head and the lower extremities (our legs) which contains all of our vital organs. And, to which our upper extremities (our arms) are attached via the clavicle (collar bone) and the scapula (shoulder blade).

  3. Merriam-Webster Dictionary: uses the word "torso" - another word - to define a word. Again, humans' trunks can also be correctly labeled "torso", but other animals, not all, can have a torso. The torso is the mid-section of a human being in which the upper and lower extremities are appended too" and where they attach, at sunken cavities, of sort, known as fossas.

  4. The Collins Dictionary: uses another word to define a word, "object". So, now humans are an object with another object attached?

So how is it that we can define the word "CORE" with another word, or a few words? This leads people to be very confused in learning and understanding their bodies.


This word "CORE" is a nebulous construct at best for people. People kind of have an idea but they can't seem to "find it" - "recruit it" - "connect to it" or "engage it".

Peoples' trunk and/or torso is the correct anatomical terminology for the central part of the human body from which extend the neck and limbs. The torso includes the thorax and abdomen. This is also where our vital organs are located and our spinal cord is housed in the vertebral column, which is attached to the skull and the cord travels through the foramen magnum (a hole in the most inferior part of the skull bones) and projects up through, and transitions into the brainstem, to connect with the brain and all its lobes and other structures. These 2 seperate, but intimately merged, structures comprise the CENTRAL NERVOUS SYSTEM, a division of the full and complete NERVOUS SYSTEM.

People can relate and understand, and process, what it means to have a "trunk" or "torso". The can see it - they have lived with it - all their lives. They intuitively know that their trunks / torsos are vulnerable to injury and hence must be protected. Learning how to protect our trunks and torsos is key to our health. How do we do that? By keeping hydrated, eating well and making healthy food choices, more often that not, and engaging in regular exercise.

When people understand the language we use, as their healthcare workers, they are more successful at implementing changes. If we give them clear and concise definitions to words and answer their questions with clear language, then they are able to learn and grow beyond our help.

I have examined ALL my didactic educational books and here is what I have found (AND these books are the books we learn theory - information - differential diagnosis - neurology - exercise prescription - surgical rehabilitation...and so healthcare workers and physical therapists - specifically:

  1. O'Sullivan's: "Physical Rehabilitation" (6th Ed.) - NO SUCH WORD/LANGUAGE (considered our "bible" for rehab and protocols)

  2. Norkin's: Measurement of Joint Motion (4th Ed.) NO SUCH WORD/LANGUAGE

  3. Goodman's: Differential Diagnosis for Physical Therapists (5th Ed.) NO SUCH WORD/LANGUAGE (another "bible")

  4. Goodman's: Pathology (4th Ed.) NO SUCH WORD/LANGUAGE

  5. McKinnis': Fundamentals of Musculoskeletal Imaging (4th Ed.) NO SUCH WORD/LANGUAGE

  6. Hillegas': Essentials of Cardiopulmonary Physical Therapy (4th Ed.) NO SUCH WORD/LANGUAGE

  7. Magee's: Orthopedic Physical Assessment (6th Ed.) NO SUCH WORD/LANGUAGE (another "bible")

  8. Kendall's: Muscles Testing and Function with Posture and Pain (5th Ed.) NO SUCH WORD/LANGUAGE (another "bible")

  9. Levangie's: Joint Structure and Function (5th Ed.) NO SUCH WORD/LANGUAGE (another "bible")

The ONE exception of all of my curriculum books: Kisner's: Therapeutic Exercise - Foundations and Techniques (6th Ed.).

BUT - let me clear on this book.....This is a "bible" for the physical therapist when we are going through our programs. It assists us in overlapping our learning guidelines from all of the other books we read. In this book's Index - they list "CORE MUSCLE AND ACTIVATION TRAINING". BUT - WHEN I ATTEMPT TO FIND THE EXACT WORD IN THE LANGUAGE - NONE OF THE 15 PAGES THAT ARE CITED USE THE TERMINOLOGY OF "CORE MUSCLE/S).

What they do discuss and highlight are ALL our body's trunk (torso) muscles from the most superficial to the most deep. This includes all anterior - lateral - and posterior muscles. NO WHERE DOES THE ACTUAL VERBIAGE OF "CORE MUSCLE/S" IS/ARE CITED AND - MORE IMPORTANTLY - EXPLAINED AND DEFINED OPERATIONALLY!!!


LANGUAGE MATTERS in the healthcare field. The way we speak to our clients and how we help them learn helps them beyond our studios and clinics. We need to be fully aware of our clients' and their needs. So, when communicating with them, we need to use language that is visually understood AND intuitively understood in terms of application within their daily lives.

Dr. Erica Nelson, PT-DPT, MSSM, BSc, MLD

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