Spinal Engine Theory

http://www.sciencedirect.com/science/article/pii/0141542587900203
http://www.alexandertechnique-running.com/george-coghill-serge-gracovetsky-and-the-spinal-engine-theory/
http://erikdalton.com/spinal-engine-vs-the-pedestrian-theory-of-locomotion/
http://www.bsmpg.com/Portals/52884/docs/Morgan.2012.pdf