Plank on the dome, cross a leg under, stay locked.
Keep your shoulders quiet and core tight, let the legs do the moving.
A forearm plank on the dome already forces your core to cancel the wobble, and threading one knee across and under your body adds rotation that your obliques have to resist and control. The moving leg constantly shifts your centre of mass, so the deep core works to keep the hips low and square. It earns a place as anti-rotation training that most plank variations never deliver.
The forearms sit on an unstable dome, so your core is already firing to stop the wobble before the leg even moves. Crossing the knee under the body then adds a rotational pull that flat-ground versions do not have.
Slow down. The crossover only counts if the hips stay low and steady, so move the knee at a pace where your torso does not react. Speed comes later.
Yes, that crossover line pulls the knee toward the opposite side, which is exactly the diagonal your obliques control. Keep the shoulders quiet and the rotation stays where you want it.
