Forearm plank meets jumping jacks.
Keep your hips level and low, don't let them pop up each time you jump.
Dropping the plank jack to your forearms takes the wrists out of the equation and sets your body at a flatter angle, so your core has to work even harder to keep the hips pinned while your feet jump wide and back together. The rhythm is the trap, every jump tries to bounce your hips up or sag them down. Great for circuits when high-plank versions bother your wrists.
The forearm position spares your wrists and puts your body at a flatter angle, which most people find makes the core work harder. If high-plank jacks light your wrists up, this is the swap.
You are powering the jump from your hips instead of your legs. Squeeze your glutes, keep the hips locked low, and make the feet do the travelling.
A steady rhythm beats a frantic one. Work in blocks of 20 to 40 seconds with clean hips, and only add time when the position never breaks.
