All that is required are supple hamstrings and back flexibility, both of which Diana, pictured below, has. As you can see, she is literally folded in half. Her forehead and shins meet, her back is beautifully lengthened upward, her legs are extended with her feet positioned on the push through bar. To deepen the stretch, she lifts her lower back higher, endeavoring to draw her legs closer to the torso. By adding a few deep inhalations and exhalations, she stretches the side body as well.