Shins on the dome, knees to chest, abs on fire.
Drive the tuck from your abs, not your hip flexors, and keep hips from spiking up.
With your shins on the dome and hands under your shoulders, pulling your knees to your chest rolls the platform forward, and your abs drive that pull while resisting the sag a long plank invites. The extension back out is where most of the work hides, your core lowering the hips slowly instead of letting gravity snap you flat. It earns a place as a genuinely hard flexion exercise for people who find planks too passive.
Same pattern, different surface. The dome sits lower and rolls less freely than a big ball, so the movement is shorter and a touch more controlled, which makes it a good stepping stone toward full stability ball tucks.
Your hips are doing the pulling. Think about curling your lower back and drawing the knees in with your abs, and keep the hips from spiking upward as they come forward.
The return. Extending your legs back to the long plank slowly, without your hips sagging, is where the core earns its keep, so never rush that half of the rep.
