what the core muscles are

Truth About What The Core Muscles Are and How To Train Them

what the core muscles are

“Core training” has become a fitness buzzword.

It’s now a catch-all term for anything between the chest and hips, but that’s not necessarily a bad thing.

For one, our clients are now more aware that core strength is important. While their understanding might be shaky, they know now that their core muscles need to be strong for overall health and performance.

This also opens up a great opportunity for you as a fitness professional to show you expertise!

When you are able to explain to your clients everything that is involved in a strong core, and how to strengthen those muscles, you are further solidifying yourself as the expert.

Let’s get into the specifics of exactly what the core muscles are, what they do, and some ways to train them.

What The Core Muscles Are:

I have listed the names and functions of the core muscles below. One could make a case other muscles contribute to core stability, but this list covers the majority of the involved muscles.

Rectus Abdominus –

This runs from the front of the pelvis to ribs 5-7. It’s primary function is spinal flexion, or bringing the front of the pelvis up towards the rib cage. This is the classic 6-pack muscle. Yes, the rectus abdominus needs to be trained, but it is far from the most important in the group!

Transverse Abdominus –

It connects to the lower ribs, pelvis, and connective tissue (thoracolumbar fascia) at the lower back. It’s main job is to increase intra-abdominal pressure. This muscle works with a few others to keep your lumbar spine safe and supported during things like squatting and lifting.What the Core Muscles Are

Obliques (Internal and External) –

These primarily run from outer part of the lower ribs to the pelvis. They also have extensive connective tissue attachments that surround the torso. These are very versatile in their function.

When both side work together they act like the rectus abdominus. When one side works alone, it causes trunk rotation and lateral flexion. Like the others, these contribute to intra-abdominal pressure

Multifidus –

It runs along the spine from the pelvis all the way up to the base of the skull. This muscle has some contribution to spinal extension. Still, it’s most important function is stabilizing the spine prior to, and during movement. Research has shown that decreased activation of this muscle is correlated with low back pain. So it is critical that we not neglect it!

Pelvic Floor –

This is a group of muscles that lines the bottom of the pelvis. It has plenty of essential functions, but for our purposes we will recognize it’s contribution to intra-abdominal pressure.

Diaphragm –

This can be thought of as the “ceiling” of the core in relation to the pelvic floor. It is the muscle that allows us to breathe, and has an intricate connection to the inside of the rib cage. With proper control of the diaphragm, we can maintain the necessary stability of the core during exercise.

Quadratus Lumborum –

Connects the pelvis to the lumbar spine. It can cause a “hip-hike” if activated unilaterally. In relation to the core, it contributes to controlling and limiting lumbar spine movement.

Why You Should Focus On These Core Muscles:

When all of these muscles work together properly they provide trunk stability.

If our clients cannot generate adequate trunk stability during high demand exercises, we increase their risk for injury.

Leg lifts and crunches are not an accurate representation of a client’s core strength.

Test how well they can stabilize their trunk with forces pushing and pulling them in multiple directions. This is how the core functions in real life!

Low back pain is very common in the fitness world, and it is not surprising when you consider the confusion around what core strength actually is.

As trainers and fitness professionals, let’s be part of the solution. We have a great opportunity to educate our client’s on what proper core training looks like.

Show your expertise and get your clients better results. That’s a pretty good deal!

How To Train Your Whole Core:

Start by teaching your clients how to posteriorly tilt their pelvis. I usually say, “bring your belt buckle up towards your rib cage.”

This is the foundation of aligning the pelvis so that the low back is in a neutral position. From here, start challenging your client’s core in multiple planes of motion.

Here are some ideas from my Instagram account:


Now that we have laid out exactly what the core muscles are, and what they do, start plugging some of these exercises into your client’s workouts this week. A proper understanding of the core muscles and their function is essential for both you and your client. It is the foundation for effectively performing any compound exercise!

Check out all of my exercises videos on my Instagram account HERE!  I post new stuff almost every day!
About The Author

Adam McCluskey

Doctor of Physical Therapy Candidate, Corrective Exercise Specialist, Certified Personal Trainer