This Is The Single Responsibility of Your Core Muscles

If you look up “core training” on social media, you’ll see some pretty cool looking exercises.  There’s a new exercise every 15 seconds that someone created for entertainment or engagement.

New things get attention, right? Who the hell is going to click on a picture of a plank?

Here’s the thing with most of our social conversation with core training: We’re missing the point. It’s essential to consider the function of the core.


You can do all of the side-bends and sit-ups that you want, but that would be neglecting the true single responsibility of your core muscles: To stop everything between your hips and shoulders from falling apart.

More formally stated, your core muscles control movement between the thorax and the pelvis. That’s it.

Your core muscles keep you together, and they do this by resisting movement.  Out in the wild, when we’re performing on a stage or a field, our core muscles help us transfer movement between the powerful muscles of our hips and shoulders.

To best prepare for our real-world activities in the gym, we do the opposite of creating movement: We resist it.

The Resistance

Your body can move to infinity and beyond, but for now, let’s look at movement as happening in three planes of motion.  We can move forwards-backwards, side-to-side, and rotate and left-right.  By considering the three planes of movement, it makes understanding our bodies, and ultimately which exercises are useful for them, a lot easier.

In reality, we’re likely moving through all three planes of motion at any time.  Our movement is complicated, and that adds to the beauty of it.  When it comes to training, I often find that there are beautifully simple principles that make sense of the complexity.  This is the single responsibility of your core muscles: Resist movement.


Let’s look at one of the simplest, and perhaps most effective, core exercises out there: The Plank.

A set of planks is typically measured in seconds, but at MFF our preference is for counting breaths. (Find out why HERE.) The plank, in all of its, non-moving, not-really-sexy-for-Instagram glory, is an anti-extension endurance exercise.  We align our hips and ribs, and we start counting breaths.  On a long enough timeline, gravity beats our ability to maintain that alignment, and we extend to compensate for this fatigue. For me, that’s where the plank ends.  For many, thanks where the plank starts.

For many, thanks where the plank starts. Rather than starting in a “neutral” position, my preference is for a pelvis position that is aggressively posteriorly tilted.  At MFF, we call this “sad dog.”  This is not a position you’ll likely find while standing, but the exaggeration is a magnifying glass for what happens in other exercises.

If the goal is to resist extension, we should practice the exercise by getting out of extension, first. Here’s an example where you can see out much of that “sad dog” I’m creating in my hips:

A plank from the knees is often looked at as easier than a plank from the toes, but the combination of the specific body position and full exhale means this short lever plank is pretty advanced.

So advanced, in fact, that I think you should practice mastering the short lever plank before trying anything else.  The ability to resist movement is of the utmost importance when training the core. It’s essential to disassociate arm movement from shoulder movement, and leg movement from pelvis movement.

I’m a sucker for progressions, but I’m also a stickler for mastering the basics. Progressing mediocrity is a great way to spread it, and while rapidly advancing may feel pretty good emotionally, it’s not going to feel good physically when you’re not seeing the results that you want.

Now, let’s try it.

You may be thinking, “This super-serious plank sounds great, but when should I try it?”

When it comes to exercises that take this much concentration and control, it’s usually best to do them early on in the workout.  Do your warm-up, and after that spend a few minutes practicing the most excellent planks of your life.

2-3 sets of 3-6 full exhales ought to do the trick.

You’ll have enough opportunities to set it up and nail it while you’re fresh, and the tension that you create in each plank can carry over to a stronger core when you’re completing the rest of your workout.

This may take a watchful eye from a coach or a friend.  If you’re lifting solo, setting up your phone to take a quick technique video for accountability can help in the learning process.  If you’d like feedback, send me the video and we’ll chat about it!

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