Lifting the back is an equestrian expression which, truly, does not mean anything, as it can be interpreted any way we want.
There is a muscular work creating upward force and preventing the thoracolumbar spine from extending under the attraction of gravity, but this complex coordination is often resumed to simplistic formulas that are so simplistic they are false.
Chazot is playing. Helyn caught him in the picture above, with her magic eye, on the flight period where the four legs are off the ground. The back is “up”, “round”, “lifted”, “flexed”, whatever metaphor we use.
The ones who want to believe that the lower line, abdominal muscles, flex the upper line, will see in this picture the demonstration of their theory. If you look more carefully, you can see that the theory does not fit the picture. The thoracolumbar flexion is not as a whole. In fact, the thoracic area is starting some extension of the thoracic spine preparing for the forward movement of the front limbs.
The ones who want to believe that the flexion of the neck does flex the thoracolumbar spine, will see in Chazot’s neck the demonstration of what they want to believe. Chazot does round his neck, but the whole-body posture does not permit to really believe that the neck does flex the back. As explained in the previous paragraph, the longissimus dorsi in the thoracic area are starting to contract, preparing the thoracic spine for the forward motion of the front limbs. At the next sequence of the canter, the hind limbs will alight first while the front limbs will be projected forward.
The back epaxial muscles, which are the muscles on and around the upper half of the vertebrae as well as the dorsal spine, create the “flexion”, “lifting’, “roundness”, that is visible in the picture. Chazot does have very strong development of his back muscles and uses it for its purpose; advanced body control for work or play. The neck position is helping him in the work of the thoracic area, creating upward force. Proper functioning of the back induces rounding of the neck as a way to enhance and ease the work of the back muscles. This is a dynamics phenomenon that we explain in the lecture, “Long and Laws of Physics”, but this has nothing to do with stretching, relaxation, and other theories commonly emphasized.
We have a picture of Charpege, a few days after her arrival at the farm. She is almost in the same sequence of the stride, but her back muscles are not developed and coordinated and therefore, she does not have the capacity of converting the thrust generated by the hind legs into upward force. The picture was taken a fraction of a second later than Chazot’s picture. Her left hind leg is alighting. She should have even more flexion of the lumbar and thoracolumbar junction. She does now, but she did not at this time. If it was the abdominal muscles and/or the effect of the nuchal and supraspinous ligament, as simplistic theories pretend, she would have been able to lift the back at the time of the picture.
In fact, due to the lack of muscular development and coordination, there is a noticeable rigidity in her body and her neck. She keeps the neck up to control her balance but does not use the elasticity and elastic energy of her neck muscles and nuchal ligament, as Chazot does, to enhance the work of the thoracic spine muscles.
There is a Samurai proverb which says “The stronger you become, the gentler you will be.” There is a peaceful power in Chazot’s picture and some anxiousness and intensity in Charpege’s picture. She did not have at the time of the picture, the muscular power to deal with her natural intensity. She is not strong enough for her spirit. If we feed them well and train them properly, most so-called behavior problems disappear.