You’ve been doing planks three times a week for two months. Your abs look a little more defined, sure, but your lower back still tightens up on long car rides, and the second someone hands you an awkward, off-center load — a couch cushion, a toddler, a suitcase at a weird angle — something in your midsection just doesn’t fire the way it should. If that sounds familiar, the problem probably isn’t effort. It’s that almost nobody ever explains what the core is actually for.
Most people train abs like they train biceps: pick a movement, load it, add reps. But the core doesn’t work like a bicep. Its primary job isn’t to create motion — it’s to stop motion from happening somewhere it shouldn’t. Once you train with that distinction in mind, the whole approach to ab work changes.
The Core’s Real Job Is Resistance, Not Movement
Spine researcher Stuart McGill has spent decades showing that the deep trunk muscles — the transverse abdominis, the obliques, the multifidus running along your spine — are built to resist force, not generate it. A crunch asks your abs to flex your spine. But in daily life and in the gym, your core is almost never being asked to flex on purpose. It’s being asked to keep your spine still while your arms, legs, or an external load try to move it. Lifting a bag of groceries off the floor with one hand, your obliques aren’t shortening to bend you sideways — they’re working overtime to stop you from bending sideways. That’s an anti-rotation and anti-lateral-flexion demand, and it’s a completely different skill than a sit-up.
This is why someone can grind out 200 crunches a day and still tweak their back picking up a laundry basket. They’ve trained flexion strength. They haven’t trained the bracing and resistance patterns that actually protect the spine and transfer force between the upper and lower body.
Bracing Beats Sucking In
Ask most people to “engage their core” and they’ll suck their stomach in toward their spine. That’s the opposite of what you want. A real brace means creating 360-degree tension around the trunk — imagine someone’s about to prod you in the stomach from any direction and you’re stiffening your entire midsection to absorb it, not hollowing it out.
A simple way to feel this: take a normal breath into your belly and sides (not your chest), then tighten your abs, obliques, and low back all at once as if bracing for a punch, while still holding that air. That’s the brace you want under a loaded carry, a deadlift, or a hard change of direction on a field. It’s also the brace that should show up under a plank — most people plank with their hips sagging and zero tension in the glutes, which turns a supposed core exercise into a slow leak of spinal stability rather than a build of it.
Anti-Rotation Work Is the Missing Piece
If your ab routine is all planks and crunch variations, you’re missing an entire category: anti-rotation. Exercises like the Pallof press — pressing a cable or band straight out from your chest while it’s trying to twist you sideways — teach your core to resist a rotational force rather than create one. Landmine rotations, half-kneeling chops, and suitcase carries all live in this same category.
This matters because most real-world back tweaks happen during a rotational or asymmetric moment: reaching into the back seat, swinging a golf club with bad sequencing, catching yourself off balance. A core that’s only ever practiced flexing forward has no rehearsal for that moment. A core that’s practiced resisting rotation does.
Loaded Carries Do More Than Grip Work
Farmer’s carries, suitcase carries, and single-arm rack carries get filed under “grip training” or “conditioning,” but they’re some of the most honest core tests available. Carry a heavy dumbbell in one hand for forty yards and your obliques on the loaded side have to fight lateral flexion the entire walk. There’s no cheating the pattern with momentum the way you can on a crunch machine.
Start with a suitcase carry at a weight you can hold for 30-40 yards without leaning, and resist the urge to lean away from the load — that lean is your core losing the argument.
Build the Progression, Don’t Skip to the Hard Part
A sensible sequence looks like this: dead bugs and bird dogs to learn the brace without load, then planks and side planks with actual glute and ab tension (not just time under tension), then Pallof presses and carries to add real resistance training, then rotational medicine ball work once the fundamentals hold up under fatigue. Jumping straight to weighted Russian twists before you can brace properly just grooves a pattern where the spine, not the hip, ends up doing the rotating — a common source of nagging low back irritation in people who otherwise train hard.
Squat University — run by Dr. Aaron Horschig, a physical therapist who’s coached Olympic lifters — put out a video called “The PERFECT Ab Workout (BUILD STABILITY)” that walks through exactly this kind of stability-first sequencing, with cues for bracing and anti-rotation work that are easy to feel in real time. It’s worth watching if you want to see these positions coached live rather than just described. Check it out below.
None of this means crunches are useless or that you need to throw out everything you’ve been doing. It just means the fastest route to a core that actually holds up — under a barbell, under a toddler, under a long flight in a cramped seat — runs through resistance training, not just flexion reps.
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