Forearms on the dome, hold the wobble, stay tight.
Fight the wobble by bracing harder, do not let your hips drop or pike.
Resting your forearms on the dome takes a hold your core could coast through on the floor and makes it live, because the surface shifts constantly and your midsection has to correct every micro-tilt in real time. The instability recruits the deep core far harder than a static surface, and the isometric hold builds the bracing you use under every heavy lift. It earns a place as the plank progression that adds difficulty without adding time.
It is harder per second, which is the appeal. Once floor planks stop challenging you, the dome forces your core to work against constant movement instead of you just holding longer and longer.
This version is forearms on the dome with elbows stacked under your shoulders. It keeps the focus on the core hold rather than turning it into a shoulder balance exercise.
Hold only as long as your body stays in one straight line. The moment your hips drop or pike, the set is over regardless of what the timer says.
