Plank with Hip Dip

Set up in a forearm plank, elbows stacked under your shoulders and your body one straight line from head to heels. From that base, rock your hips a few centimeters toward the floor on one side, let your obliques catch the movement, then rock back through center to the other side. Your shoulders and hips stay square to the floor throughout, this is a rotation at the hips, not a wobble through your shoulders. Move slowly enough to control the bottom of each dip instead of letting gravity finish it for you. If your lower back arches or your hips pike upward, you have lost the plank underneath the rocking; shrink the range until you can hold the line.