Effects of the rider on the kinematics of the equine spine under the saddle during the trot using inertial measurement units: Methodological study and preliminary results

The range of motion (ROM) of the caudal thoracic and thoracolumbar regions decreased respectively by −1.3 (0.4)° and −0.6 (0.2)° during the seated phase compared to the unridden condition. Concomitantly, the ROM of protraction and retraction angles increased in the ridden condition. This study demonstrated the ability of inertial measurement units to assess equine vertebral movements under the saddle. The rider, at the rising trot, affected the horse's global locomotion with measurable changes in the vertebral kinematics under the saddle.