Grasp handles slightly to front and stand on foot bar with knees slightly bent and hips against pad.
Raise legs as high as possible by flexing hips then waist. Return and repeat.
Exercise is typically performed without added resistance. Rectus Abdominis and Obliques only 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; see Lever Vertical Leg Raise. Waist flexion will occur earlier in lift if legs are straighter or Hamstrings are not that flexible. See Spot Reduction Myth and Lower Ab Myth.