Your Core Isn't (Exactly) What You Think It Is – And this Matters, a Lot

I’m just going to warn you as a starting place that this blog post is a little more obnoxiously technical than some of my others, but it’s very, very important. So, I’m gonna start with a little funny anecdote to whet the palate.

Like many people in what is probably the last third of their life, my dad has started taking his health a lot more seriously and has been asking me more for help figuring things out. So, I’ve started to work out with him to help him feel motivated and understand what to do.

Not that long ago, I was doing a Pilates style sit up in front of him, which is where you breath out and push your belly button as far as possible toward your back, without arching or rounding your back, and then sit up as far as you can without letting your abs out. These are very fucking hard and I can’t do that many of them without cheating, and of course my Jewish father says “Man you’re not very strong in the core, huh?” Great stuff, dad.

So I explained to him that if I was trying to do a bunch of bullshit sit ups like most people do, I can do a million of them. I proceeded to demonstrate. But that mostly uses your lower back and your “rectus abdominus” which are your superficial “six-pack” abs. But that is cheating. I am trying to actually strengthen my inner core, which is different.

This is a very common issue. People think they are doing core work and it’s mostly lower back. And it's worth understanding because core stability is sort of underneath everything else you do — how you squat, how you bend over, how you carry stuff, whether your back hurts at the end of the day. When the core isn't working right, everything downstream suffers. When it is, stuff just feels easier.

When people think "core" they usually think of that rectus abdominis I was talking about — the six-pack muscle on the surface. And it's a real muscle, it does things. But it's not the one that actually keeps you stable.

The one doing that job is called the transversus abdominis — the TVA. It's the deepest layer of your abdominal wall and it wraps around your whole midsection like a corset. You can't see it. It's never going to give you a six-pack. But it's the muscle that creates what's called intra-abdominal pressure — basically an internal brace around your spine. That brace is what protects you when you pick something heavy up, when you twist, when you absorb some kind of impact, when you do anything that requires your torso to stay solid while your arms and legs are doing something.

Then there's the psoas — it's a deep hip flexor that runs from your lower spine down through your pelvis to your thigh. The psoas is not a core stabilizer. It's a hip flexor. But it matters here because it's the muscle that takes over when your TVA isn't showing up. When you do sit-ups with momentum — yanking yourself up, rounding your back, just pumping through reps — the psoas and your hip flexors are doing most of the work. Your deep core is basically asleep.

This is how someone can do sit-ups every day for years and still have a weak core. They're training the wrong thing.

In fact, I recently had a six month – not kidding – inner thigh (adductor), hip flexor, and core injury because I was over-relying on psoas and other shit when my TVA wasn’t strong enough.

So instead of nonsense fake core movements, it's more important to learn about bracing.

Here's what it feels like: take a deep breath into your belly — not your chest. Feel your midsection expand in all directions, front, sides, back. Now as you exhale that air out, tighten your abs like someone's about to poke you in the stomach. Push your belly button to your back. But do it without over-arching or rounding your back, which is how most people cheat. You have to keep your torso straight, which feels like a small arch. (It’s easiest to feel this on the floor. Your lower back has a tiny little cave, not pushed into the floor fully but not a massive gap.) That's a brace. Your TVA just turned on.

That's the thing your core is supposed to do during a squat, a deadlift, when you're carrying heavy bags, picking up your kid — all of it. It creates this pressurized cylinder around your spine that keeps everything safe and stable.

Training this doesn't look impressive. It's slow. It's controlled. Just putting this brace off and on while breathing is doing way more for you than a hundred momentum-driven sit-ups. A dead bug done slowly, where you're maintaining that brace while moving your arms and legs – which by the way you probably cannot do very far without pooching your stomach if you’re being honest – will have your deep core shaking in a way crunches never will.

The shift is basically from movement-based core work to stability-based core work. From "how many reps can I do" to "can I hold this position without my back taking over." From speed to control. From the muscles you can see to the ones doing the actual job.

This is how you create a foundation for every other movement. This is how you don’t get hurt over and over again.