by

Dressage and In hand horse trainer

This is a short segment of IHTC. The aim of the discussion is explaining how the horse’s vertebral column work in the light of new knowledge. Jean Luc Explains how main muscles of the forelegs work as an example. It is easier to visualize the work of the front limbs muscles and then became capable to translate the knowledge into better understanding of architecture and function of the main back muscles. The discussion has already review the detailed functioning of the lower legs’ long tendons and their muscles. The discussion now focuses on the biceps of the forelegs, which is the biceps brachii.

Higher in the front leg, there is the interesting catapult mechanism of the biceps brachii. This muscle stores elastic energy in a thick internal tendon when the muscle is actively stretched during the stance phase. Also the long aponeurosis within the muscle heads represent a substantial additional series of elastic elements.  “Active stretching” is the name commonly given to eccentric contraction. The energy is then released at the end of the stance phase when the leg buckles, allowing the tendon to recoil and catapult the limb forward into swing phase. The catapult mechanism is important as it enables the horse to protract the limb more quickly than would be possible with muscle contraction alone. It has been estimated that the horse would need a muscle weighing 50 kg to produce enough power to protract the forelimb at observed speeds. Instead, the biceps' catapult mechanism provides the required power output from only 4 kg of tissue.

 “The equine biceps brachii initiates rapid limb protraction through a catapult mechanism. Elastic strain energy is slowly stored in an internal tendon and is then rapidly released to protract the forelimb. The muscle fibers are short, have little scope for length change and can therefore only shorten slowly compared with the speed at which the whole muscle must shorten, which makes them poor candidates for driving rapid limb protraction. We suggest that the muscle fibers in the biceps act to modulate the elastic energy output of the muscle–tendon unit to meet the demands of locomotion under different conditions.” (Intensity of activation and timing of deactivation modulate elastic energy storage and release in a Penates muscle and account for gait-specific initiation of limb protraction in the horse. Glen A. Lichtwark1,*, Johanna C. Watson1, Sophia Mavrommatis2 and Alan M. Wilson 1)

It is not by elongating a muscle that the amplitude of the forelegs’ movement can be enhanced. It is all about elastic strain energy but while elasticity is commonly treated from the outside, through stretching and relaxation, the elasticity that makes the horse’s move efficiently and performs optimally and soundly is about the tuning of the cells and tendinous material occurring inside the muscles. The biceps brachii for instance, is activated during the stance phase of all gaits, which is when the muscle works eccentrically. The biceps functions under the principle of stretch-shorten contraction, which, as you know, demands respect of the horse’s natural cadence. The muscle is deactivated at the end of stance and therefore, the forward swing of the front limb results for a great part from the elastic strain energy accumulated in the internal tendon during the stance. However, the energy required for the swing phase of the trot is only 30% of the energy required for the canter. The contractile elements of the biceps do have the capacity to modulate the elastic strain energy stored in the internal tendon and therefore, to accommodate to the demand of the stride or the performance. One reason is that the nervous system has the ability to change the number and distribution of muscle fibers activated through a contraction.

For simplification, we talk about the capacity of the biceps contractile elements to modulate the energy storage capacity of the internal tendon. The biceps has two heads which are composed of cells and long aponeurosis elements. These aponeurosis are additional series of elastic elements and do have a substantial capacity of energy storage. By comparison, the back muscles do not have internal tendon but are also composed of cells and connective tissues that are referred to as tendinous material and therefore are technically aponeurosis. The purpose of this explanation is familiarizing you with the thought that all muscles, include the back muscles, have the capacity to store and recoil energy through their internal architecture and even in the absence of tendon. The concept is more obvious as we explore how the main muscles and tendons of the forelegs store energy during one sequence of the stride, the stance, and use this energy for the next sequence of the stride, the swing. The concept of energy stored and then used, applies to sound functioning of the back muscles.

One might think, and how this knowledge is going to improve my riding and training skill? The answer goes the other way. Without this knowledge, one’s chances of riding, training and teaching efficiently are very slim. Equine back muscles have the capacity to store and reuse elastic strain energy through their connective tissues. Therefore back muscles are influenced by the rider’s movement at a much higher level than previously believed. The fact that the main back muscles are set in opposite direction has already dismissed theories promoting shifts of the rider’s weight. Such shifts obviously disturb the horse’s capacity to properly orchestrate the work of his main back muscles. Further understanding of the horse’s back muscles architecture is now questioning the concept of relaxation. It is obvious at this point that relaxation of the horse’s back muscles is simply a concept unrelated to the horse’s physiology. I am talking about relaxation of the rider’s back and consequently fast and large swings of the rider’s vertebral column. These excessive and rapid movements of the rider’s vertebral column create chaos in the elastic components of the horse’s main back muscles. Intuitively few good trainers have understood the phenomenon. Waldemar Seunig wrote, “The subtle S-curve of the spine allows the spine to oscillate minutely, a movement so tiny hat it is hardly perceptible to the naked eye, producing a “soft” seat. This “soft seat” differs fundamentally from a “doughy” seat, in which we find a spine that is too flexible and allowed to undulate freely in response to the horse’s movement.” Centuries earlier, The Duke of Newcastle promoted an “Unmovable” pelvis. Others trainers are clueless and promote relaxation of the rider’s back. The problem for the rider is that false theories can be very well marketed. They can appear logical in terms of human logic even if they are totally unrelated to actual knowledge of the equine physiology. This is why furthering one’s knowledge of the equine physiology is one’s only chance, as a rider, to discriminate false theories.

Every good teacher knows that clear explanation demands sound understanding of the subject. Knowledge is what a good teacher owes to his or her students. For trainers, knowledge is the key to soundness. Any training technique can make a horse winning in the show ring as long as the horse is talented enough. Only training techniques related to the equine physiology can keep a horse sound. Also, only advanced knowledge can keep up with the evolution of breeding program and the birth of extraordinary equine athletes. With greater athletic abilities come greater spirit and stronger personalities. Best horses are now overwhelming conventional training techniques and the trainers’ incapacity to evolve leads to submissive abuses such as the rollkur. “The animal no longer has any resistance to what’s being done to it. If his neck is in a bad position and it hurts, there is no way to get away from it. They give up a lot of their resistances.” (Hilary Clayton, 2006)

We created the science of motion In HandTherapy Course knowing that both, the horses and the riders’ skill are betrayed by antiquated training and teaching techniques. It does not belong to an institution to decide what a horseperson should know or believe. It belongs to each individual to decide what they want to learn and apply. The IHTC is the only course that provides advanced knowledge and solutions allowing the practical application of such knowledge. The daily discussions of the forum clearly show that whatever one’s specialty, therapy, teaching, training, all members of the course are perfectly capable to understand advanced concept and benefit from the application of such knowledge. 

Jean Luc  

Science Of Motion