The word "core" is thrown around frivolously in the exercise and fitness world. However, I find that most people have a limited understanding of what structures and functions truly encompass the area that we refer to as our "core."
This gap in understanding becomes particularly problematic when choosing exercises for yourself or your patients or clients, as inappropriate exercise selection or poor execution of certain exercises may not only not get the outcomes that you want, but may be promoting compensatory movement patterns that can affect range of motion, stability/perceived strength and may lead to undesired symptoms.
If you ask 10 people to define what "core" means to them, at least 9 out of 10 will likely say "abs." Now, while this isn't blatantly incorrect, it is dramatically incomplete.
The primary function of our "core" is to manage pressures within our ventral cavity to help achieve or maintain position of our axial skeleton (spine, ribcage, pelvis). Our ventral cavity spans from our respiratory diaphragm superiorly to our pelvic floor inferior, bordered posteriorly by the lumbar spine and anteriorly by abdominal wall with organs and fluid encased within.
In the two images below, you see the relationship between the respiratory diaphragm, the major muscle of respiration (breathing), and our pelvic diaphragm (pelvic floor).
The influence the respiratory and pelvic diaphragms have on our movement and stability are drastically under-appreciated when discussing "core" work.
Breathing and "core"
In a resting state, our respiratory diaphragm is dope-shaped with outer attachments along the inferior anterior and lateral rib cage.
As we inhale, the diaphragm descends, flattening in appearance, and the lower ribcage widens. Flatting of the diaphragm pushes pressure (and viscera) inferiorly within the ventral cavity. The pelvic diaphragm, if positioned properly, works as a hammock that eccentrically orients and "catches" the pressure.
As we exhale, picture two people on both sides of the hammock pulling forcefully, shooting you in the air. That is how our pelvic diaphragm sends pressure back superiorly. If we exhale efficiently (and fully), our respiratory diaphragm should return to a resting, dome position.
The analogy I make for my patients when trying to explain out pressure management works is to visualize a game of pong (the arcade version, not beer).
Good Not So Good
If we are able to maintain the vertical relationship between the respiratory and pelvic diaphragm with breathing and movement, we have a never ending game of pong (depicted in the image in the left).
If we are unable to maintain proper positioning, the paddle will not be in the position to send the ball back and the game will be over. Pressure will then travel to the path of least resistance (typically anterior) which will affect resting and dynamic posture and alter joint position, force production and movement quality.
(Image taken from DNS)
So why is non-specific abdominal work not necessarily working your core? We are capable of contracting muscles and moving against resistance to creating tension within our abdominals without ever achieving this optimal position. But is this optimal? Is this attacking the goal of why we want a "strong core?" No.
If we continue to arbitrarily program "abdominal exercises" without respect to position of our ribcage and pelvis, we run the risk of creating a compensatory strategy of movement that will hinder our ability to reflexively achieve these positions in the future.
So what should you do?
First, we need to be able to stack our cranium, thorax and pelvis on top of one another without our base of support. This is true regardless of the position we are in (supine, prone, standing, etc).
Then, cycle through a few breaths, in the nose and out of the mouth. At the end of a full, long exhale through your mouth, you should feel abdominal muscles kick in. Do not try to consciously contract these muscles, allow the exhale to do the work.
When you feel that abdominal tension, maintain that tension as you quietly inhale through your nose.
You should be capable of repeating this cycle losing the stacked position of your cranium, thorax and pelvis.
There is never a time where you are exercising without utilizing your "core" but if you enjoyed incorporating isolated "core" work into your workouts, always be sure to focus on positions of your thorax and hips. Excessive arching of your back, shoulder blade squeezing together or moving back away from your ribcage, shrugging of the shoulders or head jutting forward are all signs that you cannot properly control the position you are in. Modify your position or regress the exercise and you will notice a significant difference in how you feel during and after the workout.