Peak deviation from stride-average shape of the equine back in trot (a,b) and walk (c,d). The deviation in walk was less than in trot, and while the deviation from the stride-average shape exhibited a qualitatively similar profile between the two, the trot exhibited greater spinal extension and cranio-caudal curvature. Views are elevated right cranio-lateral (a,c,e) and dorsal (b,d,e). Note that within the saddle-relevant region, the area of the withers (cranial thoracic spine) deformed the greatest in trot (a,b) and walk (c,d). Grey squares represent motion-capture markers placed at (in the cranio-caudal direction): T6, tuber coxae (two markers) and Cd1.