From the Italian Renaissance onwards, the riders are going to bring their horses in a balance which is specific to higher equitation, called the ‘rassembler’. This balance alters the common posture of the horse in two aspects: in the back part (the part of the horse situated at the back of the rider), the swing of the hips entails the back legs to move forward under the horse together with a flexion of all the joints; and simultaneously the rising of the neck (upwards) lightens the front (the part of the horse situated in front of the rider). Here the horse settles into the rassembler and then comes out of it. When the back legs come close to the front legs, the surface occupied on the ground – a surface referred to as "sustentation area” – becomes reduced.
Picture credits: Pepper Only / French Ministry of Culture and Communication