The USDF rule book defines it as “…Thrust. Releasing of the energy stored by engagement. The energy is transmitted through a back that is free from negative tension and is manifested in the horse’s elastic, whole-body movement.
The classical dressage trainer Nuno Oliveira described impulsion as, “…a mental and physical state of the horse to obey the rider’s demands as fast as possible, to move forward, and to maintain his forward impulsion without support from the aids…” and “Impulsion means to maintain the energy within the cadence.”
Another definition is that “[a] horse is said to have impulsion when the energy created by the hind legs is being transmitted into the gait and into every aspect of the forward movement. A horse can be said to be working with impulsion when it pushes off energetically from the ground and swings its feet well forward.”
The USEF states, “Impulsion is the term used to describe the transmission of an eager and energetic, yet controlled propulsive energy generated from the hindquarters into the athletic movement of the horse. Its ultimate expression can be shown only through the horse’s soft and swinging back to be guided by a gentle contact with the rider’s hand.”
In competitive dressage circles, impulsion is defined by the German Training Scale, which states that impulsion is only possible in gaits having a moment of suspension, such as the trot and canter, but not the walk. This is the current position of the USDF. Others differ, however. Oliveira described impulsion as necessary at all paces: “If your horse goes from walk to trot without changing the head and neck position, the walk had good impulsion.” Outside the world of competitive dressage, impulsion is considered necessary at all gaits, encouraged in gaited horses, and in horses used for western riding. Impulsion at the walk is encouraged and judged in many lower level dressage and combined driving competitions that do not necessarily follow the current trends in international judging.