A plank with jumping-jack legs to keep your core firing under movement.
Keep your hips level and still, only your legs should move.
The Plank Jack isolates the Core — no passengers. That makes it a clean tool for adding targeted core volume without extra fatigue.
The Plank Jack primarily works the Core.
Start with sets you can hold with perfect position, even if short. Add a few seconds each session; quality beats clock-watching.
For most lifters 3 to 4 working sets. Pick the rep range that fits your goal and progress the load when the top of the range feels owned.
