The sit-up became America’s go-to “core test” because it’s easy to count, not because it’s the best way to build a bulletproof midsection.
Quick Take
- Military-grade research found core stabilization training can match or beat traditional sit-up-based training for sit-up performance.
- Repeated spinal flexion under fatigue can irritate backs, especially in older bodies with tight hips and desk-bound posture.
- Planks and stabilization drills shift the job from “cranking your spine” to resisting movement, which better resembles real life.
- The smartest question isn’t “How many sit-ups?” but “Can your trunk stay solid while your arms and legs work?”
Sit-Ups Became a Tradition Because They’re Convenient, Not Because They’re Optimal
The sit-up didn’t win America’s fitness loyalty by being perfect; it won by being practical. Schools could line up a gym class and count reps. The military could run large groups through a timed test with minimal equipment and quick scoring. That convenience quietly shaped what people believed “core strength” meant: endurance through repeated bending. The problem is that your body doesn’t care about tradition when your lower back starts complaining.
The cultural hangover still shows up in living rooms and garages: if someone wants to “work abs,” they drop to the floor and start curling. For many adults over 40, that motion happens on top of tight hip flexors, long hours sitting, and older discs that don’t love being asked to flex hundreds of times. The surprise isn’t that sit-ups can feel productive; the surprise is how often they train the wrong limiting factor.
The Army Put Sit-Ups on Trial and the Results Didn’t Flatter Old-School Training
The most interesting twist comes from research that didn’t have patience for gym myths: the U.S. Army studied what happens when soldiers train their “core” differently. In a large randomized trial, core stabilization exercises performed as well as, and in some outcomes slightly better than, traditional exercise programs built around common calisthenics. Pass rates on sit-up performance even ticked upward in the stabilization group, a direct hit to the idea that you must grind sit-ups to get good at them.
A follow-up trial in a separate soldier population looked hard at injuries and work limitations. The headline wasn’t “stabilization eliminates injuries,” because it didn’t. The point was more practical: switching to stabilization did not increase injuries and showed hints of benefits for low back issues and duty restrictions.
Why Repeated Flexion Can Punish the Back When Fatigue and Form Collide
Core training gets messy when fatigue enters. Most people start a set of sit-ups with decent control and finish it by yanking with the neck, flaring the ribs, and recruiting hip flexors like they’re trying to win a tug-of-war. That shift matters because the lumbar spine ends up moving more while the abdominal wall contributes less. Repetition under sloppy mechanics creates irritation, and irritation has a way of turning into chronic avoidance of training.
Experts who warn against heavy reliance on sit-ups usually focus on the same common-sense issue: the spine’s job is often to resist unnecessary motion, not to produce endless motion. When a workout repeatedly flexes the trunk, especially with speed or momentum, it can create “wear” that provides little payoff beyond a burning sensation. Older trainees don’t need more pain tolerance; they need more usable strength that protects joints during everyday lifting and twisting.
Planks and “Anti-Movement” Training Fit Real Life Better Than Crunching for Reps
Your core doesn’t just bend; it braces. It transfers force between your shoulders and hips when you carry groceries, climb stairs, throw a suitcase into a trunk, or catch yourself when you slip. Stabilization training aims at that job description: keep the trunk steady while limbs move. Planks, side planks, and controlled variations teach you to lock in the ribcage and pelvis, building the kind of tension that makes you feel sturdier, not just sore.
Muscle activation research supports the logic. Electromyography comparisons have shown certain plank-based drills and stability challenges can light up core muscles strongly, often outperforming traditional flexion exercises. That matters because “core” isn’t a single muscle you can isolate with enough reps; it’s a coordinated system that includes deeper stabilizers. Training that forces coordination tends to travel better into sports, yard work, and injury prevention than a rep-count contest on the floor.
How to Think Like an Adult: Train the Trunk to Endure, Not Just to Curl
Replace the old question—“How many sit-ups can I do?”—with a better one—“How well can I hold my position?” A sensible approach for most adults is simple: prioritize front planks, side planks, and dead-bug style control drills; add loaded carries if your joints tolerate them; and treat sit-ups as optional, not foundational. If you insist on flexion work, keep volume modest and form strict, not frantic.
The sit-up isn’t evil, but it’s overrated as a primary measure of “core strength,” and the evidence doesn’t justify treating it like a rite of passage. When research shows you can improve performance and protect backs with stabilization, stubborn loyalty starts to look less like toughness and more like habit.
Most people won’t change until something happens: a twinge during yard work, a stiff back after a “hard ab day,” or the realization that the body they have at 55 doesn’t recover like it did at 25. That moment is the opening. Train your core the way you actually use it—braced, steady, and strong under real-world demands—and the payoff shows up where it counts: fewer setbacks, better posture, and more confidence doing ordinary things.
Sources:
Are Sit-Ups Bad for Your Back?
Core stability exercise principles
Core exercises that are better than sit-ups
Want a stronger core? Skip the sit-ups
Are sit-ups a good core exercise?
