Adding a sense of motion to a photograph can be done in a couple of ways, either at exposure or afterwards during post processing.
For this image of Natalie, I chose the later.
Actually, I did not envision the final image when it was taken. We were experimenting with some cloth I had brought to a shoot. The image was appealing, but I felt that it needed something more. I added some motion blur in post, and I think the images becomes more dynamic as a result.
Some photographers feel that there is a purity to limiting an image to the moment of capture. I have always felt that it is the final image – not how it is achieved – that is important. If the story the image is telling is about that moment of capture, then I agree to let things stand. If not, and if the story is enhanced in post, then too so be it.