Lie supine on machine with lower legs between padded bars. Grasp handles on each side.
Pull lower leg bar up by flexing hips toward arms by flexing hips then waist. Continue to raise knees toward shoulders by flexing waist, raising hips from board. Return until waist and hips are extended down to original position. Repeat.
Rectus Abdominis and Obliques dynamically contract only if actual waist flexion occurs. With no waist flexion, Rectus Abdominis and External Oblique will only isometrically contract to stabilize pelvis and waist during hip flexion. It may be necessary to completely flex hips before waist flexion is possible. See Spot Reduction Myth and Lower Ab Myth.