Crunches can hurt your back. Here’s how to train your core safely.
Most of us learned core training as crunches and sit-ups. High reps, every day. That approach has a cost, and it shows up years later.
Ask a physical therapist about crunches and you may hear that they're the worst exercise ever invented. Ask a bodybuilding coach and you'll hear they're the foundation of a six-pack. Both are right, because they're answering different questions. If your goal is a spine that still works at 70, the answer changes—and so does everything about how you train.
The damage is cumulative
In McGill’s lab work on porcine spines, discs herniated after repeated flexion cycles under compressive load—bend, load, repeat—rather than from a single heavy event (Callaghan & McGill, 2001). We only get so many bending cycles in a lifetime.
That doesn’t make every crunch dangerous. But it makes hundreds of them a poor way to train a core whose main job is to hold your spine steady.
Start with anti-movement
Anti-movement exercises train the core to hold position against a force trying to move it. They let you do real work without adding much load to your spine, which is why they belong at the center of a home program (Galpin, 2026).
Three anti-movement patterns are worth knowing.
Anti-extension—resisting the spine arching backward. The dead bug, the front plank, and the hollow body hold all train that pattern.
Anti-lateral-flexion—resisting bending to one side. The side plank is an option, and so is the suitcase carry.
Anti-rotation—resisting twisting. The bird dog and the Pallof press both train it: in one you resist the twist that comes from extending opposite limbs, in the other you resist the pull of a band anchored at your side.
Load it without grinding your spine
More time under tension and more reps are real progression, but they’re only one pathway, and not the one your core responds to best. Your abs also respond to force production. That means loading big, controlled movements instead of piling on reps. Galpin’s point is that core muscles aren’t special—the limited fiber-type data we have puts them close to your quads, so there’s no reason to train them with hundreds of daily reps when we’d never train anything else that way (Galpin, 2026). For strength, what matters is how hard the muscle contracts, not how many reps you do.
But that comes with a real problem. Load a spine that's flexing and you're back to the mechanism McGill's lab found.
Galpin gives us a solution: big loaded movements are the safest way to reach high force demand without putting the spine and hips at serious risk (Galpin, 2026). At home, that means doing exercises like a heavy suitcase carry, a weighted dead bug, and a loaded hollow hold instead of classic crunches and sit-ups.
Here is an example of a core training progression:
Master the position—always start with learning proper form. Hold a clean front plank or hollow hold, no sagging, no arching, for 30–45 seconds before you add volume.
Add controlled volume—include slow dead bugs and bird dogs, with attention on the lowering phase.
Only then add load—hold a wall ball, kettlebell, or dumbbell through a hollow hold or dead bug, or carry a one-sided load for distance.
For example, once a static Hollow Body Hold is solid, try the variations that keep the same fixed back position while loading the exercise in new directions. The Hollow Body Tricep Extension ramps up the anti-extension demand. Moving one arm at a time, like in the Hollow Body Alternating Press, adds an anti-rotation challenge to the movement. In all cases, the low back stays fixed to the floor. The moment the low back lifts, you need to shorten the lever or drop the weight.
Most people get excellent results without ever going beyond these three steps.
My top five: every pattern, loaded, no spinal grinding
These are the five exercises I keep coming back to. Between them they cover all three anti-movement patterns, and every one can be progressed with weight rather than more reps.
