Crunches
Short upper-back curl — isolates the rectus abdominis without the hip flexors taking over.
Execution
- Lie on your back, knees bent, feet flat on the floor.
- Hands lightly behind the ears or crossed over the chest.
- Lift only the shoulder blades off the floor — the lower back stays grounded.
- Lower under control, never fully losing tension at the bottom.
Tips
- Chin loose toward the chest, but do not actively pull — the abs do the work, not the neck.
- Add a 1-second hold at the top to increase the stimulus at the same rep count.
The sit-up's little sibling — and the better one
In a crunch, only the upper back lifts off the floor while the lumbar spine stays down. That's exactly where the difference lies: the range of motion is small, the compressive forces on the discs sit well below those of a full sit-up, and the rectus abdominis still gets trained in its one real job — flexing the trunk.
The trunk has four jobs, and flexion is only one of them. Crunches are therefore not a complete core exercise, just a useful complement to stabilizing work like the plank and the dead bug.
Execution
Lie on your back, knees bent, feet flat. Hands rest loosely at the temples or crossed over the chest — not clasped and pulling behind the neck. The sternum moves toward the pelvis, the shoulder blades lift barely off the floor, nothing more. Hold briefly at the top, then lower under control.
Common mistakes
- Pulling on the head. The most common mistake. It shifts the load into the cervical spine and makes the exercise pointless.
- Coming up too far. Past roughly 30 degrees, the hip flexors take over. At that point it's a sit-up with all its downsides.
- Using momentum. Without control on the way down, half the work is missing.
Programming
Two to three sets of 12 to 20 reps, performed slowly, are plenty. If you can do more than 25, don't add more reps — slow the tempo down instead, or move to a harder flexion exercise like the hollow hold or leg raises.