Is Your Core Weak? How to Tell


Hey, can I ask you a quick question?

What is the core?

It’s funny—but for all talk about how important the core is, not everyone feels super clear on WHAT it actually is. I’m talking about both geography and function here.

There’s a very simple reason for this lack of clarity: core is a made-up term.

Made-up doesn’t mean bad or wrong. It’s a convenient way to address trunk stability and connect it to back health, athletic performance, and all that good stuff. Sometimes, the idea is expanded to mean abs or to relate to a specific exercise. There are some inherent problems with this, though. This often leads to an acute case of broken telephone. Take the following example:

“I have lower back pain.”

“I was told that I have to strengthen my core.”

“I started doing crunches every day.”

“Crunches hurt my back.”

“Maybe I’m just broken.”

Have you ever read one of those ads that say, “It’s not your fault!” Well, it’s not your fault. If the above sounds like you, I assure you that you’re not broken or doomed to live in pain. You’ve just been doing the wrong stuff.

Here’s why

Often, the type of back pain people experience is flexion-based. For example, someone with this type of pain may sit all day with their spine in flexion. Choosing a movement like crunches INCREASES the intensity and frequency of the positions that are giving them trouble in the first place. Dammit—that’s a hard swing in the wrong direction!

There are a ton of assumptions above, starting with the idea that core strength and back pain are related. They may be. Then again, that back pain might relate to anything from low-back endurance, to lifestyle demands, to basic biomechanics. We need to figure out what’s going on first.

Let me insert a quick disclaimer here. Diagnosis is best left to the pros—you know that. With that, if you’re pain-free—or already super-clear on your needs—let’s play around a bit.

Let’s figure YOUR stuff out!

The ability to stabilize your spine is fundamental. Even when you play a sport—like golf or judo—that demands spinal movement, stability comes first. Due diligence for back and hip health here still comes down to your ability to lock things down at will. What you add on top of that is up to you.

Easily the most common example of static control is the plank. Gravity is trying to pull you into extension and you’re having none of that nonsense.

Spinal extension

One important piece of advice: planks are not one-size-fits-all! If you have ever experienced back pain during (or after) a plank, please check out this video.

Exercise example #1: how you plankin’?

Is your core weak or strong?

To answer this question, let’s first define what strong means. In our world, a strong core is one that can resist spinal movement demands (flexion, extension, or rotation) AND have a buffer.

The strength and endurance to resist movement

The plank is an example of an anti-extension exercise. Merely getting into the position isn’t a guarantee that good things are happening, though. Being tuned into what you feel and being able to adjust things is a huge piece of the puzzle. At the end of the day, that’s the difference between a ritual and an effective action. A ritual is burning a candle and praying for money. Effective action is robbing a bank.

With something left over

A buffer means that your strength, endurance, and movement strategies exceed demand. This protects you when things go wrong. It also ensures that you can hold this position for more than a second—since endurance takes priority over strength for preventing low back pain.

The buffer described here is hugely important because being responsive is part of the equation. Taking a massive breath, pushing out your abs with all available force (and until you go beet red) is entirely appropriate for a maximal effort. That’s not only standard but necessary in sports like powerlifting. The demand and the response match. However, if you’re going beet red to tie up your shoes, something is up. We often see a lack of responsiveness in people with low-back pain. In other words, they have trouble matching up the strategy to the demand.

From Low Back Disorders (McGill)

So, what do we measure?

There is no fixed measurement. Yes, there are some research-based standards (see above). The truth is, though that your ability to resist movement and look good doing depends 100% on what your demands are. This is not only relevant to fitness demands but to everything else. A blacksmith has different demands than an accountant and a stuntman has different demands than a taxi driver (hopefully).

Evil Ki-spinal

Exercise example #2: Are your hips stiffer than your spine?

Ok, it’s time to move your hips. Let’s try a simple experiment: standing up (feel free to use support), bend one knee and push your heel backwards. You should be able to keep your low-back in an unchanging position until you find the end range of your hips. In other words, your hips should be mobile and your back should be stable. Many people will experience more movement in their low-back than their hips. If this is what’s happening to you, your hips are never going to get a chance to be mobile. It’s like having a spring in the middle of a teeter totter. You push one side down and—instead of the other side coming up, you just stretch out the middle. The middle, in this case, is your low-back—and it may not be loving it.

This is not usually a strength issue so much as a coordination and awareness issue. So, how do you fix it? The same way you get to Carnegie Hall. Starting with this drill is great. The ultimate goal, however, is seamless and automatic integration—no mental effort required.

Exercise example #3: Is your upper-back stiffer than your lower-back?

When you’re making a stability sandwich, the bread needs to be made of mobility. In other words, to have a truly stable low-back, the structures above (thoracic spine) and below (hips) have to be mobile. Mobility and stiffness are relative. If EVERYTHING is tight, you might not need much work to increase mobility. If EVERYTHING is loose, adding stability to the low-back is easy. However, if the low back is loosey-goosey and the hips/thoracic spine are tight, you’ll have some real work to do.

Once again, you can address this by practising this in a stripped-down manner and then reintegrating into more complex movement.

Also worth noting: this is why stretching your low-back isn’t always a good idea.


As nice as it would be to have absolute numbers or standards, the truth is that nobody has needs quite like yours. We can guess at minimum requirements based on basic lifestyle demands but anything beyond that must be personalized. So, look closely at the kind of demands that you experience and reflect on how your body feels. At the end of the day, your job is to cultivate the type of strength and skill necessary to exceed them AND look good doing so.

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