From the extracellular matrix to posture. Is the connective system our true Deus ex machina?

Edited by Dr. Giovanni Chetta

The first task of the lower limbs is therefore to provide the energy that allows us to move at high speeds. Thanks to them, intervertebral movements and rotations on the transverse plane in particular, can take advantage of the complementary contribution of the hamstring muscles (hamstring , semitendinosus and semimembranous) to which the spine is connected through specific and considerable anatomical myofascial chains:

a) sacrotuberous ligament - longissimus lumborum muscle (located on the sides of the spine)
b) sacrotuberous ligament and iliocostalis thoracis (in this way the right hamstrings control part of the left thoracic muscles and vice versa),
c) gluteus maximus muscles - opposite great dorsal muscles (which in turn controls the movement of the upper limbs).
All these hamstring-spinal cross connections form a pyramid that ensures strong mechanical integrity from the lower to the upper limbs. The fascia is therefore necessary to transmit this complementary force for the specific motion of man from the lower extremities to the upper ones.

The "energy impulse goes up along the lower limbs" filtered by them (ankle, knee and hip represent critical passages in this regard), so as to reach the vertebral column in the appropriate phase and amplitude. In this way the trunk can use this energy by rotating each vertebra and the pelvis appropriately (Gracovetsky, 1987).
However, the rotation of the pelvis around the vertical axis, which occurs during walking, by means of muscles that pull it downwards presents an efficiency problem.
This problem is solved by using the gravitational field as a temporary reserve warehouse, in which the energy released by the lower limbs at each step is accumulated: in the ascent of the center of gravity (deceleration phase) kinetic energy is stored, as potential energy, and subsequently retransformed into kinetic energy to accelerate the body (the body is lifted at the expense of the kinetic energy acquired in falling). The relative curves are therefore in phase opposition: the "increase in potential energy occurs at the expense of kinetic energy" and viceversa. In typical walking (speed 7 km / h), muscular activity is required only to maintain the relationship between the two forms of energy in the terms consonant with the specificity of the process. In other words, the muscular factor is not asked to make facing the periodic ascent of the center of gravity but to control the contribution of the environment by modulating the instantaneous ratio between potential energy and kinetic energy, containing it within the limits of the construction of the specific motion. Since this task is delegated to the red (aerobic) muscle fibers, it results to low energy consumption (Cavagna, 1973): a subject weighing 70 kg in a 4 km flat walk sustains an energy expenditure covered by the ingestion of 35 g of sugar (Margaria, 1975). For this reason, man can be a tireless walker unlike quadrupeds, whose motion with bent joints requires a much greater expenditure of internal energy. (Basmajian, 1971)
Thanks to the myofascial system, therefore, man obtains, within the gravitational field, a specific motion of maximum efficiency. Our initial hypothesis is therefore proven.

Static?

The specific motion of man can be defined as the set of dynamic, energetic and informative events that converge in the bipodal alternating gait (motion with progression) and in the standing position (motion without progression). The "static" is actually a special case of walking, it is characterized by postural oscillations, visible and quantifiable through the "stabilometric examination, corresponding to rhythmic movements on the transverse and frontal planes. As motion without progression, the standing position includes the" inhibition of movement with the relative additional decelerating muscular intervention. It is therefore more difficult and more expensive from an energy point of view than normal locomotion: man is made to walk (on natural ground).
Posture must therefore be defined within a dynamic concept: Posture is the "personalized adaptation of each individual to the" physical, psychic and emotional environment. In other words "it's the way we react to gravity and communicate " (Morosini, 2003).

"Artificial" life

The cultural factor can act on the normal postural physiology by altering the environmental information, thus interfering with the normal evolutionary process. Habitat and lifestyle more and more "artificial" lead to postural alterations in the "civilized" man that negatively affect his physical and mental health and its beauty (Chetta, 2007, 2008).

We have seen how the control of the lumbar lordosis, a typical and exclusive characteristic of mankind, is a determining factor: it allows to minimize stress and to optimize biomechanical efficiency through a correct distribution of loads and functions between fascia and muscles. Two factors have a particular influence on it, then on the whole posture: breech support and occlusal support.