Sit on machine with back against padded lever. Push hips back against back of seat by pushing feet against platform. Arch back in "C" shape.
Extend spine until hyperextended. Return and repeat.
To avoid hip movement, push hips back into seat by pushing feet into platform throughout exercise. Position foot platform, so small space remains between edge of seat and back of lower thigh. Use seat belt if it becomes difficult to stabilize hips. See Low Back Debate. Also see exercises on old Nautilus Machine and MedEx Low Back Machine.