Crunch and twist to carve those obliques.
Twist through your core, not your neck. Let your obliques pull the elbow in.
Driving your elbow across to the opposite knee adds rotation to the crunch, which pulls the obliques into the movement alongside the upper abs. Alternating sides trains your torso to flex and twist under control, a combination straight crunches never touch. All you need is floor space, which keeps it in rotation from warm-ups to finishers.
Close cousins. Bicycle crunches keep your legs pedalling continuously, this version keeps your feet planted and works one deliberate twist at a time, which makes it easier to control and to feel in the obliques.
Your hands are dragging your head forward instead of your core lifting your shoulder. Keep the fingertips light behind your ears and think about turning your ribcage, the elbow follows on its own.
Contact is a nice target, not the goal. A full rotation with your shoulder blade off the floor beats a sloppy tap where only your arm moved.
