• Dr. Elaine Screaton DC

What is your Core?

Most of us have heard of 'the core' of the body, but what is it really?


Your core is the 'centre' of your body. Think bottom of the rib cage at the diaphragm (your big breathing muscle) to the pelvic floor, and everything in between!


This image shows your 'Core'. Note it starts at the diaphragm, ends at the pelvic floor, and wraps the entire way around the abdomen!

Several years back, it was thought that the core was made primarily of the rectus abdominus muscle (our muscle that gives people a six pack). We know better now that it encompasses all muscles of the abdomen, including rectus abdominus, transverse abdominus, internal oblique, external oblique, the diaphragm, the muscles of the pelvic floor (these basically keep your pelvic organs and intestines inside of you and not on the floor), latissimus dorsi, lumbar erector spinae and lumbar multifidus muscles. That is a whole LOT of muscles, not just one. SO, it is no surprise they must work together to form a strong core.


The other misconception is that we strengthen the core by moving the core (think sit-ups), when in reality our core's main job is the stabilize our spine and body and allows us to transfer forces rather than moving. We also tend to develop a stronger core when engaging all of the above mentioned muscles at once, instead of trying to selectively spot train. This is because we need our core to function most when we aren't thinking about it! Next time you reach into your fridge to pull out a container of milk or something slightly heavy (bottle of wine etc), pay attention to what your core does. I bet you contract your core without even thinking!


For the core to perform well, we must have good motor control (ie the nerves tell the muscles to turn on at just the right time), and we must have good endurance. Core strength (ie the ability to lift heavy loads with the core) is less of a predictor of good core health and of future health and disability. Athletes with better core stability (ie better motor control and better core endurance) are less prone to injury. This means less prone to injury in the low back, hip, knee, shoulder, neck (and almost any other injury) because the core acts at the centre of almost any motion of the spine and limbs!


Signs you have a weak core:

1. Have frequent low back pain. The core supports the low back most directly, so a weak core means you are more likely to have low back pain.

2. Poor Balance. Either you find yourself losing balance easily, perhaps falling more often than you should, or you find yourself constantly needing to support yourself as you move around (grabbing on to railings, walls, counters etc)

3. Poor Posture. You might notice your shoulders constantly hunched forward, or feel like the curve in your low back is too large, or like your butt sticks out when you walk.

4. You hold your breath during core exercises. Instead of breathing with your diaphragm while doing core exercises, you find yourself holding your breath until the exercise is done. This is a sign you are unable to use the diaphragm while using the remaining core muscles which is a problem, we need to breathe!

5. Unable to hold a front plank or trunk flexor position (with good form!), back extension or side plank (with good form) for approximately the same amount of time. This means, you should be able to hold a front plank for approximately the same duration before fatigue as a back extension plank, and your side plank on the right should be about the same as the side plank on the left. Mismatch between these indicates weakness in core endurance, and potential for developing low back pain or other dysfunctions.



These 4 exercises test core endurance in all planes. Remember, the core must be strong in all planes to be considered strong.

Stu McGill's Core Endurance Tests:

1A: Trunk Flexor Endurance Test.

1B: Left Side Plank Endurance Test

1C: Right Side Plank Test

1D: Trunk Extensor Endurance Test


*Stu McGill is a leading researcher in the field of spinal stability out of Waterloo, Canada. He is best known for his fantastic moustache, but also his exceptional research on biomechanics of the spine and rehab of the back pained individual. Check out Dr. McGill and his moustache here.


The goal of these is to demonstrate where imbalances exist, which can then lead to a targeted rehab program to gain a stronger core! But again, the core must be strong in all of these planes, as deficiency in 1 means there is a breakdown in overall core stability. Before attempting these tests, please ensure you are not currently suffering from acute low back pain. The trunk extensor test is not possible to complete on your own, so you will need a friend, or to simply use a back extension machine found at your local gym.


What to do if your core is weak? (ps, this is most of us, as sitting at our desks all day greatly deactivates the core)


Check out my blog next week to see some of my favourite core exercises that are easy to perform!



Dr. Elaine Screaton (DC, BSc) is a Chiropractor in NW Calgary, currently practicing at Synergea Family Health Centre in Calgary, AB.





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© 2019 Dr Elaine Screaton

Tel: 403-247-2947

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