Does core work give you flat abs or help with back pain?

As a Pilates teacher, I’ve noticed that people are drawn to core work for one of two reasons:

  • They want flat abs
  • They have back pain and they heard strengthening their core will help

These are widely accepted benefits of core strength, but are they true and if so, what defines a good core exercise? Crunches? Planks? Anti-rotation? There’s a lot of options – and opinions!

I’ll start with this.

With the exception of plastic surgery, that weird procedure where they freeze sh*t, or liposuction, you can’t spot reduce fat.

You could spend a lifetime doing crunches (or any targeted core work) and it still wouldn’t reduce the amount of adipose tissue on your stomach. The only way to reduce that without the aforementioned surgical interventions is some sort of change to nutrition and caloric intake.

Total buzzkill, right? I too wish that crunches were the antidote to pie, but sadly the science isn’t there (side note, I <3 pie).


However, it isn’t all sad pandas and frowny faces. A strong core could make your abs look flatter, just not the way you might think.

Here’s the deal.

Contrary to the way it’s marketed, your core is more than a washboard on the front of your body. Rather, it’s two layers of muscles that act like a 3D ring, running from the bottom of your ribs to your pelvis and wrapping from the belly button around the sides of your body to connect to the back at your spine.

You can think of these two layers of your core as an inner unit and an outer unit (and bare with me, because this really does relate to your back pain or what your stomach looks like in a bathing suit.)

The inner unit is the deeper layer of abdominal muscles including the transverse abdominis, pelvic floor, multifidus (little muscles around your spine) and diaphragm. It primarily stabilize your spine and regulate intra abdominal pressure (aka it plays a large role in breathing + pelvic floor control and helps prevent your guts from falling out).

The outer unit is comprised of your pretty muscles like the rectus (6 pack), obliques and erectors (the big muscles in your lower back). Its main purpose is to help you move (bending, twisting, running) and to resist movement (not collapsing your spine in a deadlift or stopping your body from twisting against resistance).

Ideally, these units work together to create efficient, pain free movement. However, if you breathe poorly, sit too much and or are chronically stressed (because…well…life), your abdominals may not engage well.

In some cases, the inner unit doesn’t fire well, but the outer unit works. When this happens, you may be able to perform challenging ab exercises, but your abs will dome out during the exercises and when you’re casually standing. This is why you can see a slender or well-muscled person who still has a stomach that domes outward.

Sometimes, the inner unit will turn on, but the outer unit fails. In this case, your abs will draw in at the right time during an exercise or movement, but there will be a rotation or shift in the ribs, hips or spine.

Sometimes neither unit engages well and you’ll see a mix of all the things I described above.

Anecdotally, I find this to be the most common thing I see. Most of us have a little delay in how our inner unit fires (aka we have to work really hard to connect to it during mundane looking exercises like toe taps) and some general imbalance and weakness during certain movements, which would indicate an issue with the outer unit.

Any of these core timing issues can cause back pain, but for different reasons.

In the case of an inner unit failure, back pain often occurs for two reasons. First, the outer unit is overworked or over recruited, because it’s trying to both move you and support your spine. This results in sore, angry, stiff muscles. Second, because your inner unit isn’t doing what it needs to be doing to stabilize your spine, you get spinal compression and in turn discomfort and pain.

With an outer unit failure, you’ll typically have a weakness or imbalance with one side of your outer unit muscles (e.g. a weak QL or oblique on the left) and you may be prone to habitually rotating into or compressing on spot in your back, which again sends signals of sore angry muscles, tension and pain, especially if you try an exercise that your body isn’t strong enough to do without collapsing into that weak spot.

And again, if neither is engaging, then you’ll experience a mix of everything I described above.

While the end result is the same, this matters, because the inner and outer unit respond to different types of training and even if you don’t have back pain and you’re perfectly happy with what you abs look like, it’s still beneficial to do core work with both units in mind.

So now that we have that out of the way (cue big sigh of relief), how does this apply to core training?

Let’s talk inner unit first, because it’s the foundation of everything you do and if you don’t have a functioning inner unit, then you’re moving from an unstable, compressed spine, which is…not great.

The inner unit really should engage pretty much every time you take a breath or even think about moving, so aside from focusing on breathing, you really can’t isolate it from the outer unit.

Does Core Work Give You Flat Abs And Help With Back Pain? #flatabs #backpain #core #pilates #naablevyThis isn’t to say that you can’t observe if it’s working. Personally, I like to start with simple unloaded exercises like heel slides or alternating leg lifts lying on my back, where I see if I can move my leg without popping my abs. However, I can also apply that same test to sit up or a plank, because if the abs dome, I know the inner unit isn’t working and I need to back track to an easier exercise until I find a level where the abs don’t pop.

Beyond that, I don’t care if you’re twisting, resisting twisting, crunching, extending, bending or anything else – it’s all outer unit.

The question just becomes if you’re doing an anti-rotation exercise (e.g. a plank or bird dog where you lift a leg or arm and try not to twist) can you do it without creating shifting in the ribs and hips or sagging in your spine and if you’re doing a spinal movement exercise (like a roll down or a Russian twist) can you move easily through your spine and fairly symmetrically between your right and left sides?

Now that being said, if you cranky back, it’s often helpful to start with unloaded spinal movements to reduce stiffness and down regulate any over recruitment coming from the big core muscles (aka outer unit) and follow it up with anti-rotation work, since it can help get the inner and outer unit to work together to stabilize the spine…and then assuming you don’t have a condition where it’s contraindicated, start adding in more dynamic exercises that challenge control during spinal movement.

And if you need example of this, I’ve created quick routine based on these ideas…or in not so fancy terms – a crunchless ab workout 😉

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