What does it mean to follow the movement in dressage?

Following the movement describes the rider's ability to absorb the horse's motion through a supple, flexible body rather than resisting it with tension — the quality that allows the horse to move freely underneath a rider rather than being disturbed by the rider's stiffness or being forced to accommodate a rider who cannot follow the natural oscillation of the horse's gaits. Each gait produces a characteristic movement pattern in the horse's back and body that the rider must absorb if the horse is to move with freedom and expression: the walk's four-beat lateral sway requires the rider's hips to move forward and back alternately with each step; the trot's two-beat diagonal push creates an upward oscillation through the horse's back that the rider must absorb through a soft, opening hip joint; the canter's three-beat rocking motion requires the rider's seat to follow the characteristic forward-and-down, upward-and-back sequence of each stride. A rider who cannot follow the movement in any gait will instead restrict the horse's back — the horse's muscles will tighten in response to the rider's stiffness, producing the dead, inactive back that restricts impulsion and suppleness. Following the movement is not a passive quality — it requires active engagement of the rider's core muscles to maintain the upright position while the hips and lower back absorb the horse's motion — but it is a fundamentally receptive quality rather than a driving one. The classical instruction to sink into the saddle rather than to sit tightly on it captures something important about following: the rider who releases into the horse's motion allows the seat bones to follow the horse's back rather than perching rigidly above it.