Stretching and bending are very common Vipassana exercises.
But I like, yoga asana during the vipassana retreat. Because that balance the vital energy through out the meditation period. In Vipassana exercise you have to keep your spinal cord flexible. During vipassana meditation you can place both thumbs on the navel and during thumbs on the navel, observe the movement of the breaths. You can also fold the tongue upward and bring to the meeting point of all uper doors (both eyes, both ears, both nostril and mouth) and try to suck the Melatonin Hormon. Sidha Asana, Dhanur Asana and Gomukh Asana are effective.