The OG ab move. Small range, big burn.
Only your shoulders lift, not your lower back. Don't pull your head with your hands.
The crunch isolates the rectus abdominis by curling only the ribcage toward the pelvis, a deliberately short range that keeps the hip flexors out of the movement, which is exactly what full sit-ups fail to do. Because the lower back never leaves the floor, tension stays on the abs from start to finish. It earns its place as the simplest way to train the abs directly with zero equipment.
For targeting the abs, yes. Sit-ups turn into a hip flexor exercise past the first few inches, while the crunch keeps every rep on the abs. If your hip flexors or lower back complain during sit-ups, switch.
You are pulling your head with your hands. Keep the hands light behind your head or cross them on your chest, keep a fist of space under your chin, and lift by squeezing the abs, not by yanking the skull forward.
Treat them like any other exercise, a few sets taken close to failure beats hundreds of sloppy reps. When 20 slow controlled reps feels easy, slow the tempo or add a pause at the top rather than chasing bigger numbers.
