The interconnectivity of the horse’s musculoskeletal system, and the complexities of movement is continuously being unravelled and has taken large steps recently as we have delved into the realms of myofascial lines and bio-tensegrity. Research has also quantified the hoof, as the ground interface, and its effects on both static and dynamic posture, along these myofascial lines and kinetic chains, showing the hoof to be the beginning and end of a closed kinetic chain.
However, recently the theory of bio-tensegrity has been called into question, perhaps though we can merge the thought processes, suggest a missing and vital component that controls these systems as simply what makes them functional. Offering and discussing a concept of neuro-bio-tensegrity akin to the push puppet effect, whereby an energy must be given to the tensegrity for it to become functional.
Myofascial lines, Kinetic chains, and Bio-tensegrity
Biomechanical research has been dominated using lever models and kinematic analysis, however, Elbrond and shultz (2015) have suggested that the myofascial kinetic lines provide an anatomical foundation for an improved understanding of locomotion in a more holistic way, rather than the simplified description of levers and pullies.
Fig. 1 The superficial myofascial lines, showing the interconnectivity of the muscle chains and lines of influence through the body.
They suggest that the lines inform practitioners with a way to track root causes of gait asymmetry and poor performance. The theories of myofascial lines and bio-tensegrity acknowledge that movement, and indeed standing still, is a complex orchestration of events involving many different body systems simultaneously affecting one another by way of a continuum of connective tissue. This contrasts with the mechanical view of movements broken down and isolated, which limits the ability for holistic consideration. This is perhaps what has established a “treat the symptoms” habit within equine medicine.
Dischiavi et al. (2018) discusses bio-tensegrity which suggests the bones of the skeletal system are held together by the resting muscle tone of numerous viscoelastic muscular chains in a tension dependent manner.
Fig. 2 The horse represented as a series of compression resistant elements (the bony skeletal system) that have no rigid connections, which are held together within a web of continuous viscoelastic tension elements (the musculotendinous system).
Bio-tensegrity system theory suggests that when movement happens, the entire musculoskeletal system adjusts causing global patterns to occur. This idea is of course supported by the anatomical evidence of myofascial lines, suggesting that muscles can no longer be viewed as independent anatomical structures that simply connect one bone to another bone. Rather, the horses body consists of numerous muscular kinetic chains connected in series.
Fig.3 Examples of muscular kinetic chains along myofascial lines. These are the 4 major superficial lines that extend all the way into the hoof.
The myofascial lines and extended myofascial network, are an avenue for force transmission, essentially between any anatomical point and any other, as the horses body becomes one interconnected musculoskeletal system. While there are myofascial “lines” the complex interaction of the lines with one another, create global kinetic chains, this again supports the bio-tensegrity ethos whereby the position and orientation of each anatomical part is a result of the loadings and functional demands of the wider system.
New research into the complexities of bio-tensegrity have now included the tensions created by nervous tissue, the vascular tissue, the movement of the viscera and bodily fluids (liquid fascia), such as blood, lymph, interstitial and intracellular fluids, recognising how body fluids can manipulate mechanical tensions faster than muscles and govern functionality (Bordoni and Myers 2020). Bordoni and Myers (2020) express how while myofascial lines and kinetic chains provide a fundamental understanding of the body as a continuum, the current concepts do not include all the components to explain the nuances of a mobile existence.
Therefore, while as I have presented here, there is anatomical evidence for myofascial lines, kinetic chains and logical thinking behind bio-tensegrity, the discussion of these theories often lack understanding of integral components that control these systems and ultimately stops the body from being a pile of connected tissue, on the floor. One being the nervous system.
While fascia itself has been postulated to have inherent tension and impart a continuous tension to the system, it is suggested both intrinsic tension AND active contractions are responsible for the tension within the system. Importantly It has been proposed that the resting muscle tone throughout the musculoskeletal system is important in providing compression and tension between the bones, giving the body the ability to be upright and mobile (Dischiavi et al. 2018), however, a muscle truly at rest (asleep or dead) doesn’t provide any tone!
Tensegrity theory suggests that tensegrity structures are a series of compression resistant elements (the bony skeletal system) that have no rigid connections, which are held together within a web of continuous viscoelastic tension elements (the musculotendinous system). Therefore, It is clear the horse’s body can be viewed as a large tensegrity system, as the bones have no rigid connections between one another, but are supported by musculotendinous structures that provide constant elastic tension within the system, even at rest. However, It has also been proposed that the resting muscle tone throughout the musculoskeletal system provides the compression and tension between the bones, necessary for the body to be upright and mobile. Without the muscle tone, there is no tensegrity, unlike the tensegrity models that are inert and “self-stressing”, the body requires a signal for muscle tone, an energy input, then the bio-tensegrity comes to life.
This is where we introduce our push puppet effect. Bio-tensegrity does exist, but in a biological, living, moving form, it is the nervous system that acts as the push button. Before the button is pushed, a push puppet still has all its components connected, along a kinetic chain that will all move when one component is stressed, but it is not functional until that external stress is applied to the system.
So, the horse and human for that matter, becomes a neuro-bio-tensegrity, this then helps us to further grasp the emerging research linking posture, neuropathy, muscle tone and hoof balance.
The neuro-bio-tensegrity
The difference between what we will term neuro-bio-tensegrity and a tensegrity model, is the tensegrity model is inert and is held into place by inherent tension. A neuro-bio-tensegrity can change itself, by manipulating amount of muscle tone, whether conscious or a result of unconscious proprioception and/or haptic perception. But, the continuous tension that exists has to be made, and then can be manipulated and moved, creating changes in posture, and ultimately movement, as the neuro-bio-tensegrity that is the horse, utilises a closed kinetic chain to manipulate ground reaction force vectors. While the horse can manipulate tensegrity it doesn’t have enough tension without nervous input to remain standing, however, the fact still holds true that the interconnection of the body, the kinetic chains and myofascial system, still enforce involuntary full body involvement during conscious isolation of a single muscle unit.
Muscle tone is clearly a component of a neuro-bio-tensegrity, and muscle tone is controlled by nerve innervation, Palmer, back in 1910 discussed “Tone, in biology, is the normal tension or firmness of nerves, muscles or organs, the renitent, elastic force acting against an impulse. Any deviation from normal tone, that of being too tense or too slack, causes a condition of renitence, too much elastic force, too great resistance, a condition expressed in function as disease.” The effects of neurological issues on bio-tensegrity can in part be seen by conditions such as “wobblers” whereby proprioceptive in put and the communication of the body along neuro-pathways dictates the timing of the button being pressed and the efficacy of the bio-tensegrity unit. If bio-tensegrity was completely passive, relying solely on muscle chains and fascial connections, then that system would override neurological dysfunction.
These concepts of neurology affecting bio-tensegrity can be extrapolated, and are perhaps more comparable to tensegrity models, when considering static posture. Changes in the resting tone of muscles will change tension along kinetic chains within the myofascial lines, creating changes in global posture. This being a result of nervous “tension” can then extrapolate proprioceptive input affecting global tensegrity. This more complete evolution of bio-tensegrity to neuro-bio-tensegrity helps us to underpin the findings of three major proprioception areas affected by human intervention, dental occlusion and the TMJ, the upper cervical region and hoof balance affecting global posture. Proprioceptive input influences innervation and resting muscle tone and this change, travels along the connective pathways affecting tensegrity, and forming a default posture.
In conclusion, the existence of bio-tensegrity has been questioned in the light of the nervous system (amongst other body systems) being responsible for the interconnectivity of the body being functional. However, rather then detracting from this important concept that informs holistic analysis of postural and locomotory issues, they can be merged to bring further understanding and inform a more and more holistic approach. The bio-engineering, evolutionary genius use of bio-tensegrity is possible through the incorporation of a skeleton built on with muscle, connected universally by fascia and switched on by the nervous system. A bit like the electric shock that brought Frankenstein’s monster to life, or the elastic potential energy your finger puts into a push puppet.
References
Bordoni, B. and Myers, T. (2020) ‘A Review of the Theoretical Fascial Models: Biotensegrity, Fascintegrity, and Myofascial Chains’, Cureus, 12(2). doi: 10.7759/cureus.7092.
Dischiavi, S. L. et al. (2018) ‘Biotensegrity and myofascial chains: A global approach to an integrated kinetic chain’, Medical Hypotheses, 110(April 2017), pp. 90–96. doi: 10.1016/j.mehy.2017.11.008.
Elbrønd, V. S. and Schultz, R. M. (2015) ‘Myofascia - the unexplored tissue: Myofascial kinetic lines in horses, a model for describing locomotion using comparative dissection studies derived from human lines’, Medical Research Archives, (3). doi: 10.18103/mra.v0i3.125.
Elbrønd, V. S. and Schultz, R. M. (2021) ‘Deep Myofascial Kinetic Lines in Horses, Comparative Dissection Studies Derived from Humans’, Open Journal of Veterinary Medicine, 11(01), pp. 14–40. doi: 10.4236/ojvm.2021.111002.
Levin, S. M. and Martin, D.-C. (2012) ‘Biotensegrity’, Fascia: The Tensional Network of the Human Body, (December 2012), pp. 137–142. doi: 10.1016/b978-0-7020-3425-1.00054-4.
Paulo Caldeira, Keith Davids, Duarte Araújo, (2021) Neurobiological tensegrity: The basis for understanding inter-individual variations in task performance?, Human Movement Science, Volume 79, 102862, ISSN 0167-9457, https://doi.org/10.1016/j.humov.2021.102862.
Palmer DD: “Text-book of the Science, Art and Philosophy of Chiropractic for Students and Practitioners.” Portland Printing House Company. Portland, OR. 1910. Page 7.
Sharp, Y. and Tabor, G. (2022) ‘An Investigation into the Effects of Changing Dorso-Plantar Hoof Balance on Equine Hind Limb Posture’, pp. 6–8.