Spiderman Plank

Set up in a high plank, hands under your shoulders, body in a straight line. Bring one knee up toward the same-side elbow, rotating slightly through your hips as it comes forward, then place the foot back and switch sides. Keep your hips level rather than letting them pike up or sag as your leg moves — the plank itself shouldn't change shape, only your leg. Move at a pace where you can control the rotation each time rather than swinging the knee up and back on momentum.