Are Crunches and Situps Actually Worth It?

Short answer: For 99% of people, no. Your core's job is to protect your spine and keep it stable, not to flex and extend repeatedly. Crunches cause your vertebrae to open and close, pushing the disc out. Studies show a connection between excessive crunches and bulging or herniated discs. Weighted crunches (cable crunches, machines) make it even worse. Train your core the way it's meant to be used: anti-movement exercises that resist flexion, extension, and rotation.

Okay, so today's question is: are crunches and situps worth it?

Short answer: no. For like 99% of people.

Why crunches don't make sense

The issue with crunches and sit-ups is, I know the logic there is like "oh flex the muscle, make the muscle bigger." That isn't always the case.

What you should ideally be doing is using muscles in the way they're most intended in your body. The core is intended to protect your spine, keep it stable, keep it from over-bending or overextending or snapping in half.

So it makes more sense to use those muscles the way they're meant to be used.

The disc problem

The other issue with crunches (sit-ups kind of depends on how strong your core is, for some people core's strong enough that situps are okay): crunches specifically cause your vertebrae to open and close, to flex and extend.

What happens when you do that: as it opens, the disc that's in the middle gets pushed out. And when it closes, a lot of times it doesn't come all the way back in as fast as you're doing it.

If you're doing it very slowly, maybe it would be okay. But as fast as it's flexing and bending, that disc gets pushed out over time.

Studies do show a connection between excessive crunches (or flexion/extension at the spine) and bulging or herniated discs. (Dr. Stuart McGill's research on spine biomechanics is foundational here.)

Weighted crunches make it worse

And that's just body weight. Let alone if you add weight to it.

A popular one is get the rope on each side of your head and do cable crunches. That's just going to amplify the problem.

Same with the seated weighted crunch machine. That's going to make it way more likely as well. I really discourage those variations.

What to do instead

You can do kind of an anti-crunch. What I like to do is separate (usually when someone says sit-ups they mean crunches). I separate the two.

Crunches are when you're doing that repetitive rounding. Whereas a situp, at least how I refer to it in my terminology, is if you can keep a neutral spine and then come up within your range of motion. Not come up too far to where you're bent into your lumbar, but just to where you're bending at your hip.

The better approach is to train your core for what it's actually designed to do:

Exercise TypeExamplesWhat Your Core DoesAnti-extensionPlanks, dead bugs, ab wheel rolloutsResists spine from extendingAnti-rotationPallof press, single-arm carriesResists rotation forcesAnti-lateral flexionSide planks, suitcase carriesResists bending to the side

These train your core the way it's meant to function: stabilizing your spine, not repeatedly flexing it.

Further reading:

• Dr. Stuart McGill's work on spine health