Building a Functional Core: The Muscles Involved and How to Engage Them

Whenever someone talks about their core, what’s the first thing you picture?

Probably that ever-coveted six pack, right?

While you wouldn’t be wrong in envisioning that ideal set of abs as the core, you also wouldn’t be entirely correct,either. There’s much more to the core than what you see on the surface.

While “core” often refers to the middle of something, your body isn’t built spherically like an apple or a planet. It’s made up of a highly complex system of interconnected muscles, bones, tendons, and ligaments — and supporting all of those structures requires more than just a singular, dense centerpoint.

Your true, technical core runs way deeper than that.

Anatomy of the Functional Core

In the context of our anatomy and biomechanical movement, the primary purpose of the functional core is to provide stability. And since your body (and all its extremities) can move through three different planes of movement, you can bet that it needs a LOT of stabilizers to move.

So, before we dive into building a functional core, let’s review what it actually consists of.

Abdominal Muscles (Anterior Trunk)

We know you probably already associate your abdominals with the core; most people do. But for the sake of a comprehensive breakdown, it’s important to acknowledge the different layers that your trunk comprises.

The rectus abdominis is that iconic six pack muscle. It’s the most superficial layer of muscles in your trunk and is primarily responsible for trunk flexion (bending forward).

Beneath the six pack are your oblique muscles, both external and internal. Your external obliques line both sides of your abdomen, attaching from the middle of your rib cage down to your hip bone. Just underneath are your internal obliques, which line both sides of your lower abdomen, from the lower rib cage to the bottom of your pelvic bowl. Together, both obliques aid the rectus abdominis in flexing the trunk.

Lastly, there’s the transverse abdominis, which is the deepest core muscle that travels all around your torso. (Some people visualize it as a muscular corset around the ribcage, since the fibers run perpendicular to the spine.) In tandem with its counterparts, this muscle helps stabilize your torso and provide additional support to your lower back and pelvic region while moving.

Altogether, proper strength and activation in all your abdominal muscles creates increased protection for the spine and stability in your torso.

Spinal Muscles (Posterior and Internal Trunk)

However, your front abdominal muscles aren’t the only source of stability for your trunk — there are a handful of muscles around your spine and within the torso that play a key role in a truly functional core.

Along the spine, you have a handful of muscles: the spinalis, the longissimus, the multifidus, and the quadratus lumborum.

Looking at these diagrams, you can infer that these multi-layered muscles are deeply interconnected with your spine and its movement. For instance, both the spinalis and longissimus allow you to move the spine laterally or bend backwards (including the neck, to some degree).

Quite similarly, the multifidus muscle provides additional support when the spine rotates, tilts to the side, or extends backwards. The quadratus lumborum also allows you to extend the lower spine, though it further contributes to trunk and pelvic stability, particularly during rotational movement.

This group of paraspinal muscles are key for protecting the spine and prompting extension in the back. As a result, they provide significant stability for your torso and pelvis during movement.

They aren’t, however, the only important muscles — we also have the latissimus dorsi and psoas muscles to thank.

Your latissimus dorsi muscle (also known as your lats) make up a majority of your back, connecting to your shoulder blades, spine, and the top of your hip bones. These muscles are essential for trunk and core stability.

It’s common to consider the lats as part of the back and not part of the core, but their connection to the pelvis is the most significant aspect to its functionality. This direct attachment to the hips allows for stronger stability with rotation, lateral bend, and back extension.

And you may be able to infer that the psoas muscle has a similar importance simply based on how it connects to the spine and pelvis. The psoas is the deepest set muscle of the core, and it’s the only muscle that connects your trunk to the lower leg, so it is incredibly important for core and lower leg stability in the big picture.

Pelvic Muscles

This is the point where most people don’t associate the muscles with the core: the pelvis (i.e., the gluteal and hip muscles).

Below are some of the largest, most significant muscles that contribute to your core — the gluteus maximus, gluteus medius, and adductor muscles of the hip.

Though your gluteal and hip muscles don’t fit the conventional idea of what your core comprises, they’re absolutely essential for stabilizing the body during movement. Each muscle has specific functions within the body, but when combined, they create increased stability for your hips and thighs.

Let’s put this into perspective. Your hip joint naturally has a wide range of motion, allowing your leg to move forwards and backwards, side to side, and rotationally in most directions, all of which we recruit regularly in our day-to-day movement. In order to maintain sufficient control over these mechanics while also retaining proper balance (particularly for single-leg movements), the joint requires ample stability.

That’s where the glutes and adductors come into play. These muscles surround the hip joint to best control your biomechanical movement, and their anchorpoint to your pelvis is what allows for improved stability and correlation to your trunk and core.

Pretty neat, right?

Importance of a Strong Functional Core

Alright — you made it through the anatomy lesson!

Now that you’re well-versed in all the moving parts that go into your true, technical core, we can finally address why functional core strength is so important for your movement.

Your core is responsible for resisting forces against the body to maintain positioning and movement in any direction (or, in other words, it helps you keep your balance and enforce stability so external forces don’t knock you over). The complexity of your core muscles allows you to resist forces in all planes of movement!

But the core isn’t just about stabilizing your body. When your abdominal muscles work together, they help regulate something known as “internal abdominal pressure” to keep your organs protected and in place throughout movement.

A common analogy is to compare your trunk with a soda can…

Picture the cylinder of an empty soda can: this represents your trunk, and the walls of the can equate to the walls of your abdomen. If you compress the can from top to bottom with external force, the structure is surprisingly robust, and the walls of the can are stable enough to prevent any actual compression.

However, if the can has a dent on one side, it’s much easier to crush the can when applying compressive forces:

Of course, this isn’t a perfect translation to trunk stability. (Your body can’t be “dented” like a can, and having weaker muscles on one side of your abdomen doesn’t mean your entire trunk will cave in and impact your organs.)

The basic premise, though, is significant — your core requires sufficient support and consistent muscular engagement to maintain its structural integrity.

So, let’s review what it means to engage your core and how to do it.

How to Engage the Core

Isn’t it annoying when people tell you to engage your core, but they don’t tell you how you’re supposed to do it? (That’s the worst.)

Or maybe, like many people, you’ve recently learned that when you thought you were engaging your core, you were only activating some of the muscles, leaving those soda can sides structurally unsound. 

Learning how to recruit your core muscles isn’t all that difficult to accomplish; it just takes a bit of guidance to get a good handle over what it feels like to activate them. And one of the best ways to familiarize your body with that kind of activation is to recruit the power of some common cues, whether it’s during exercise or otherwise.

Common Cues for Engaging the Core

There are two primary cues that people default to: breathing, and bracing.

Okay, not exactly just breathing — more specifically, it’s suggested that you draw in your abdominal muscles as you exhale deeply. This motion generally engages your deeper core muscles and obliques, and you can further specify this muscle activation by focusing on your posture, as well. (Which we’ll review in the next section!)

Conversely, you can practice bracing your core muscles, which sounds like what it is. Focus on firming up the muscles in your abdomen to keep them contracted. It can sometimes be helpful to visualize a hard impact hitting your core, like if someone were to punch you in the stomach or drop a bowling ball on your abs. (We said it could be helpful, but not necessarily fun to visualize.)

Many people find abdominal bracing to be more effective than the breathing technique, as it doesn’t interfere with your natural pattern to inhale or exhale.

Which brings us to an important aspect of engaging your core muscles: once you feel your muscles contract and stay active, make sure you breathe normally!!

It might seem like an odd thing to remind people to do, but it’s a natural response when we aren’t used to isolating the core muscles for activation. Many people will engage the muscles and then hold their breath without realizing, but that doesn’t allow for true muscle activation. (It just sort of holds your muscles in place, rather than actually activating them.)

So, as you practice engaging your core, make sure you breathe comfortably while retaining that contraction in your abdomen — that’s the real key. And if you can’t do it at first, don’t worry! It takes a little while to get good; it’s normal to start an activity braced and find that somewhere along the line, your attention drifts and you lose it a little. 

Postural Considerations

Here’s the thing about engaging your core: you can do it pretty easily with these cues, but you have to be sure they’re being done correctly. (As is often the case.)

For instance, you can learn how to draw in or brace your abs, but doing so doesn’t guarantee that you’re really engaging those inner abdominals, too. A simple way to check is to engage your core and see if your rib cage flares out, which is typically indicative that your rectus abdominis (that six-pack muscle) is stronger than your deeper core muscles.

To address this, sit (or stand) with your back upright, keeping your spine in a neutral position. Draw in your abdominal muscles as mentioned, and focus on retaining that straight posture without flaring out your rib cage or leaning forward with your torso. (If you’re prone to slouching while you sit, there’s a good chance you’ll feel the difference in your abs when channeling that activation!) You can also apply this same technique while lying down on your back.

It’s also important to be aware of your pelvic orientation. Even though the common cues for engaging the core are predominantly focused on your trunk muscles, your spinal and pelvic muscles still have an important role in proper core engagement.

If you find that your pelvis tilts forward while activating your core, it’s typically associated with a lack of stability in either your oblique muscles or transverse abdominis. When these muscles in the front of your trunk aren’t being properly utilized, your body compensates by relying on your paraspinal muscles instead, ultimately pulling at your tailbone and the back of your pelvis to cause that forward angling.

Signs of posterior pelvic tilt, on the other hand, are often correlated with the inverse issue of weakened paraspinal muscles. This results in compensatory reliance on the abdominal muscles that will pull the front of the pelvic bone upward and create that backwards tilt.

Long story short, just as with any other biomechanics, simply “doing” isn’t enough to be doing it correctly. (And that goes doubly so when your core involves so many muscles with so many connections to different body parts.)

Focus on the feel and presentation of your form. Seeking external feedback — whether it’s recording a video to watch your form or working with a physical therapist — is a key component to mastering your core work.

Steps to Building a Functional Core

Now, dear reader, you have a deeper understanding of what your true core is actually made of, and how all of its pieces come together to create full-body stability through our everyday movement.

The next step? Take this foundational knowledge and apply it!

Stay tuned in the new year for the second post of this blog series, where we’ll walk you through what it means to build a functional core, how to do it, and what exercises are most beneficial to dedicate your training time to.

Images courtesy of KenHub.

By Megumi Kamikawa

Megumi is a graduate from San Jose State University with a degree in English, Creative Writing. Previously, she has worked as a Writing Specialist, where she served hundreds of peers in the SJSU community with her knowledge of English pedagogy. In addition to her experience with academic, creative, and professional writing, she has experience with creating visual and informational resources for various audiences. She has enjoyed taking courses on anatomy and basic physiology, and continues to educate herself in the world of health and wellness through her work with Competitive EDGE.

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