Forward movement should not be understood as how much the horse’s body is moving forward but instead as how well the thrust generated by the hind legs is transmitted forward through the horse’s body. Great authors have emphasized the concept over and over warning, “Do not confuse speed and impulsion.”
While familiar beliefs attribute the greatest amount of vertical impulse, (self carriage,) to the hind legs. Scientific measurements have demonstrated that at the contrary, 57% of the vertical impulse is produced by the forelegs while only 43% is created by the hind legs. “In horses, and most other mammalian quadrupeds, 57% of the vertical impulse is applied through the thoracic limbs, and only 43% through the hind limbs.” (H. W. Merkens, H. C. Schamhardt,G. J. van Osch, A. J. van den Bogert, 1993).
The practical application of this phenomenon is the purpose of this training session. Chazot’s vertebral column is properly orchestrated at the walk and Jean Luc is asking the horse to keep proper mechanism of the vertebral column at the trot. When Chazot succeeds, the forelegs’ upward propulsive activity does increase. In equestrian terms, the movement is going through the horse’s shoulders.
At the first attempt, the movement did not go through and Jean Luc encourages Chazot to understand the concept moving forward at the rising trot.
At the third attempt, second on the video, the movement did not really go through but the idea was in the Chazot’s mind and the Jean Luc confirmed Chazot’s thought keeping the sitting trot on the circle.
At the fifth tentative, Third on the video, the movement went through and Jean Luc rewarded Chazot at the rising trot. As we replay the sequence in slow motion, you can see the change in the propulsive activity of the forelegs which occurs at the third trot stride.