What Is the Core, and How Do I Strengthen It?

We hear the term “core” all the time when it comes to exercise. But what does that term actually mean?

The term “core” can be confusing. You might think, “Isn’t my heart just my stomach muscles? Aren’t I working it when I’m doing crunches? ”

But actually, your “core” is made up of a lot of different muscles, and as a physical therapist who specializes in women’s health, I am very familiar with the core.

I’m here to give you a rundown on what, exactly, your core is, why we love it, and how to take care of it. (Spoiler alert: It’s not just about your abs!)

When we refer to the core, we are referring to several groups of muscles, not just one. We should also talk about these muscles as “movers” versus “stabilizers,” and I’ll explain what that means as we get further along.

The main components of the core are:

  • the rectus abdominis (your six-pack abs) at the front
  • the internal and external obliques on the sides
  • the transversus abdominis (the deepest abdominal muscle that wraps around your midsection horizontally)
  • the erector spinae (the rope-like muscles next to your spine)
  • the multifidus (a very deep muscle that runs along your spine)
  • the quadratus lumborum (another deep muscle in your lower back, above your hips)
  • the diaphragm (this breathing muscle is the top, or the roof, of your core)
  • the pelvic floor muscles (these make up the bottom, or floor, of your core)

Together, these muscles work to provide support and strength for your abdomen.

It can be helpful to think about the image of a barrel when thinking of your core muscles, with the diaphragm on top, the pelvic floor on the bottom, and the other muscles wrapping around the middle in various directions.

Your core is basically what holds you upright.

It provides stability for your spine and trunk and allows for bending and moving of your spine. It aids in balance and postural support, helps prevent falls and injury, and helps produce sport-specific movements to generate torque and force.

Your core muscles can be divided into two categories, based on their functions: stabilizers and movers (1).

The stabilizing group (transversus abdominis, multifidi, pelvic floor muscles, and arguably, diaphragm) help maintain intra-abdominal pressure and keep you stable and strong. They don’t move or bend your body.

The erector spinae, rectus abdominus, obliques, and quadratus lumborum are the “movers.” They help you sit up, bend over, twist, bend to the side, bend backward, and more.

You need a proper balance of stability and mobility to be at your functional best. In people who have a weak core or “non-functioning” core muscles, I typically see increased lower back and spine pain, as well as injury.

That’s because your core muscles not only generate movement for your body but also act to protect your spine and internal organs against forces outside your body, such as gravity and high impact ground reaction forces.

Often, I see people (especially new mothers!) Overuse the “movers” and try to stabilize with them – using muscles that are better suited to move their spine than to stabilize it.

In this case, I often see people overusing the rectus abdominus or the obliques to try to keep them stable, when those muscles are better suited for bending and flexing.

I also see atrophy or shrinking of the multifidi in people with chronic low back pain, indicating that there is weakness in and / or difficulty with recruitment of these muscles (2).

Proper training of and exercise for the core isn’t just about strength. Strength is definitely important, but we also need to look at how the core muscles are functioning, so that there is a balance of stability, mobility, and coordination.

Effective core training is about learning to use the muscles at the right time, developing motor control as well as endurance of the muscles, fine-tuning activation patterns, coordinating engagement with your breath, and maintaining consistent abdominal pressure (3).

That being said, it’s important to vary the type of core exercise you do rather than stick to one type (so, don’t just do crunches). There are tons of fun and different types of exercise and movements that target all aspects of your core.

Pilates, some types of yoga, and kettlebell training are all examples of multi-planar core exercise that target all aspects of your core, both deep and superficial.

And don’t forget about stretching, foam rolling, and other forms of myofascial release to keep your range of motion intact and your joints happy and mobile.

YES! In one study, researchers found an increase in core stability and strength in a group of participants who completed a 4-week program that included pelvic floor exercises along with exercises for other core muscles such as the transversus abdominis and multifidus (4).

Numerous studies have found improvements in core strength and function when proper pelvic floor muscle activation and release are added to a core strengthening program (5, 6, 7).

It’s important to understand that the pelvic floor muscles make up the “floor” of the core, so it makes sense that in order to have a fully functioning system, the floor has to be “on,” or activated, to help control abdominal pressure. .

Think of a toothpaste tube that’s open at the bottom. What happens when you squeeze the sides but don’t have the cap on? The pressure squirts all the toothpaste out!

The same thing happens with the pelvic floor: Stability increases in the core and spine when all parts of the system, including pelvic floor muscles, are working properly and at the right time.

The answer to this question depends on who is answering it and where you hear it! The “right way” to engage your core will vary depending on your body, any injuries you have, your prior experiences, and your goals.

When working with my clients, who are mostly mamas-to-be, new mamas, and seasoned mamas, I like to instruct them to “bring in the foundation.”

This refers to a coupled contraction of the deep abdominal muscles and the pelvic floor, coordinated with the breath. All parts of the core have to draw in properly.

This principle can be applied to any type of movement or exercise: Think about drawing in, from all sides, when doing planks, lifting kids or grocery bags, squatting, or doing any Pilates-based exercise.

You want controlled, solid contractions without bearing down, holding your breath, letting one part of your core off the hook, or compensating with other muscles that shouldn’t be on.

If it’s hard, it’s better to do less than to do more without proper activation and movement. Think quality over quantity!

Think of your core as a symphony of muscles and structures that all have different purposes and needs. It’s your job to nurture all of them. Vary your core exercise, think of mobilization and stabilization, and focus on quality over quantity. And don’t forget about your pelvic floor!


Marcy is a board certified women’s health physical therapist and has a passion to change the way women are cared for during and after their pregnancies. She’s the proud mama bear to two boys, drives a minivan shamelessly, and loves the ocean, horses, and a good glass of wine. Follow her on Instagram to learn more than you want to know about vaginas and to find links to podcasts, blog posts, and other publications related to pelvic floor health.

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