In continuing our narrative of the human nervous system, no one can deny the phrase that “Motion is Life, Motion is Freedom!” That is because a prerequisite of motion is you have to have an active, living nervous system including both the peripheral (PNS) and central nervous system (CNS). In short, the position and motion of your skeletal structure that I see in the clinic is all about the sensory input and motor output that involves your nervous system.
Your body, your nervous system has been created with an inherent intelligence which sometimes seems so simple it is hard to believe. However, one thing you can take to the bank is that your nervous system is designed to respond quickly to sensory input. Along with your history of injuries and surgeries and even your emotional wounds and habits will create the output by which your body functions on a daily basis.
In short, your body, your nervous system is shaped by the way you use it on a daily basis and conversely, your body will shape itself the way you use it. That is especially true when it comes to your posture and movement. Your habitual patterns of how you hold your body, holding patterns, and how you move within these holding patterns, become your own, unique posture and movement that I see in the clinic. It is your nervous system doing the best it can do with the information it is provided from within and outside of your body on a daily basis.
Your posture and movement is unique because no other person in the entire world shares your history, your body, your nervous system, and more importantly your experiences of life that creates your posture and movement. Like your fingerprints, you own it! However over time, these holding and resultant movement patterns can become dysfunctional that can only lead to pathology if not changed.
It is the repetition of these dysfunctional patterns over time that gives them a stronger imprint on your nervous system creating additional compensations. Unless you alter these dysfunctional holding and movement patterns they can affect the alignment of your isolated joints and of the integrated skeletal structure that eventually leads to pathology of your soft tissues, bones, and joints most of us experience later in life.
Thankfully because of your body’s innate wisdom, it has the potential, the ability to change these patterns. Once you start down this new path, it can open that door to “freedom of motion” allowing you to live your life as you chose within your potential.
It is your nervous system including the PNS and CNS that allows this to happen. A system that is not one physically, continuous system as seen with your connective tissue and vascular systems, but rather a network of billions of individual, independent cells. These nerve cells then communicate with each other through electro-chemical synapses allowing for the transmission of nervous impulses that accomplish the various functions of your body with only one goal in mind. That is, to keep you safe and alive.
It is a nervous system based on a foundational theory titled the “Neuron Doctrine.” A creation of the Spaniard Santiago Ramon y Cajal in 1906, that earned him a Nobel Prize in medicine. It is now the universally accepted theory describing the human nervous system. That is, billions of neurons communicating across electro-chemical synapses. Transmitting the neural impulses that is the foundation for any task in your body to keep you alive and well including your posture and movement.
This very complex and elaborate communication system must work in total synchronization to allow your body, your structure to work with and against the force of gravity in order for you to sit, stand, walk, and run. All things most of us take for granted. It is your nervous system that allows you to live as you know it which can be described as the dynamic process of neural input and output.
The first stage of this dynamic, communication loop is sensory input. As with all bodily functions, sensory input comes from three sources which include outside of the body and the external environment called “exteroception,” from inside of the body and its internal environment referred to as “interoception,” and from the sense of position and motion of the body referred to as “proprioception.”
The holding (postural) and movement patterns I see in the clinic on a daily basis are the end result, end product of this sensory input. Sensory input that begins with the vertical force of gravity (G) and its partner in crime ground reaction force (GRF). Gravity is the constant force which the inherent design of the human nervous system detects. Because forces naturally come in pairs, GRF is the opposite vertical force to gravity. That is because according to Newton’s Third Law of Motion, “For every action (force) in nature there is an opposite and equal reaction.”
In short, gravity keeps our human structure on the earth and the GRF helps us push off the earth. Also keep in mind, that the quantity of pushing off (GRF) will depend on the quantity of force pushing down which is gravity. In fact, the GRF should actually move like a wave of energy through your entire three-dimensional structure.
However, the dysfunctional postural, holding patterns in reaction to the force of gravity that occur along the full length, width, and depth of the human structure, can block or impede this wave of energy that comes from the ground and GRF. As a result, the body has to use its own internal tensile forces, thereby working harder and with less efficiency against gravity during movement.
I think Ida Rolf, Ph.D., the founder of structural integration (Rolfing) stated it best, “The gravitational field of the earth is easily the most potent physical influence in any human life. When the human energy field and gravity are at war, needless to say gravity wins every time. It may be man’s best friend and reinforce his activity; it may be his bitter enemy and drag him to physical destruction.”
In short, Ida Rolf is saying that your body and how it functions is more efficient and stronger if your nervous system works with the forces of the earth rather than against them. In addition, it is a given that your body works better when the isolated joints of your skeletal structure cooperate in an integrated manner rather than competing with each other in their response to these vertical forces.
Too often we describe gravity as the enemy of our human structure, when it can be our best friend. Keep in mind that gravity is a constant your body competes against every day of your life no matter what you are doing. Because of this consistency, however, gravity usually wins in the end. That is the greatest thing I learned on my own, personal journey in the sport of nordic ski jumping.
In addition to these external, vertical forces of gravity and GRF, friction has to mentioned. It also appears everywhere in your life, but it is a horizontal and not a vertical force. It is important for stability when you stand and walk. Without this external, horizontal force, it would make these everyday, functional tasks more difficult. Have you ever tried walking or even standing on ice?
A characteristic of movement that also needs to be mentioned is momentum. By the way, momentum is not a force, but a quantity of motion. It is an indication of how much internal, tensile force the body has to produce in order stop your motion in any given interval of time.
Thus far, everything I have mentioned, except for momentum, has to do with the external environment and its affect on your body. But as already mentioned, we also have to consider the internal environment and the sensory input. In particular, the internal, tensile forces generated by the action of your muscles, tendons, and connective tissue (fascia/myofascia) affecting your skeletal structure. Along with these tensile forces, I would be remiss without mentioning the internal force of friction that occurs between the articulating joints of the human structure. With some, these frictional forces can become dysfunctional and create joint pathology as with arthritis.
However, the primary internal, tensile forces are created by the “proprioceptive” sensory input against the external forces of gravity and GRF stimulating your muscles, tendons, ligaments, and connective tissue that affects the alignment of your isolated joints and integrated skeletal structure. The output of these tensile forces provides your nervous system with information on where your body is located in space at any moment in time. It is kind of like the “you are here” sign on a building or mall directory.
This proprioceptive input as it is referred to is received through a network of neuromuscular receptors including the golgi tendon organs (GTO), muscle spindles (MS), and ligaments as well as proprioceptive receptors found in your skin and other connective tissues. All these proprioceptive receptors in total are responsible for sending information into your CNS that will aid your brain to determine where you are in relation to these vertical forces mentioned.
It is no surprise then that “proprio” means self and refers to your body’s three-dimensional map of itself in space and time. It is this proprioceptive system that is responsible for your neuromuscular sensation that is also referred to as “somatosensation.” It is the input from these proprioceptors that allows you to build an accurate understanding of where your body is and what it’s doing. Foundational when it comes to creating higher quality motor outputs. Remember what happened to Simone Biles at the Olympics? She lost her proprioceptive awareness that allowed her to do the very complex and difficult movements she does in the sport of gymnastics.
But along with the proprioceptive input just described, the communication loop of sensory input which is also referred to as “afferent” information, includes information coming from your eyes and middle ears. While it is important to remember that sensory input comes from the three sources of proprioception, visual, and vestibular, it is also important to remember that not all sensory input is treated equally by your brain.
It is the input from these three sources of sensory input that contributes to the output that becomes the posture and movement I see in the clinic. That is because your brain organizes this sensory input in sort of a neural hierarchy with the visual input having top priority followed by the vestibular and proprioceptive systems.
Anatomically, the importance of the visual system can be understood considering that 60% of your actual, total brain, neuronal activity is involved in some way or another with vision. We trust our eyes more than any other sense. Therefore, vision and movement cannot be separated. They are like peanut butter and jelly in that they always have to be considered and discussed together. You have of course heard the phrase, “the eyes are the window to the soul.” But to be more exact, it should be said, “eye movements are the key to unlocking and altering the nervous system.”
This summary from a recent article I read sums up the importance of visual input: “Consider for a moment the relationship between vision and the motor output it controls. Although it may be convenient to talk about visual cortex on the one hand and motor cortex on the other, there is no particular point along the many routes between retina and the muscles, and the muscles where signals stop being sensory and suddenly become motor. From the moment signals from the photoreceptors enter the CNS, the information they convey is on its way of being transformed into motor output. This is not mere semantics. The artificial division of the brain into visual and motor areas, and the mutual isolation of the intellectual traditions that study them, have led to theories of brain function that are quite misleading.”
Because of the importance of eye movements involving the function of your nervous system, they are used by many professionals today to determine its performance and the status. From the quick side line tests during athletic competition to the modern psychology correlation between eye movements and common cognitive and emotional disorders, ,to the determination of intoxication by law enforcement officials, the importance of vision in regards to your nervous system, its performance, and its status is emphasized.
To comprehend this importance of vision, just listen to this description of gross and fine motor movements. Gross and fine motor movements are determined by motor units which consists of one nerve fiber going to a certain number of muscle fibers. When that one nerve fiber is activated, all of the muscle fibers innervated by this one fiber contract at the same time. For example, the soleus muscle in your lower leg and calf has gross motor movement because the ratio of an individual nerve fiber to muscle fiber is about 1 to 2000. That is, all 2000 muscle fibers contract at the same time when the nerve fiber is activated or facilitated. Large patches of the soleus muscle then contract simultaneously giving the meaning to gross motor. The result is the soleus muscle gives you a lot of power, but not a lot of fine muscle control.
Compare that to what happens with the muscles of your hand where the ratio to nerve fiber to muscle fibers drops significantly. When thinking of fine motor skill, one naturally thinks of the hands. The ratio goes down to one nerve fiber for every 150 muscle fibers giving you fine motor skill. But when you get to the eye, the ratio drops even further and can get as low as one nerve fiber to one muscle fiber. It makes it the finest motor control in your body or 150 times finer than the control of your hands.
These ratios emphasize how precise the motor control of the visual system is. The reason for this is because the area on the back of your eyeball that actually sees things clearly is only one millimeter in diameter. Therefore, the muscles that position your eyeballs have to be extremely accurate for you to see. So you can see why the eyes are key to understanding and altering the human nervous system.
In this neural hierarchy of sensory input, however, the vestibular system comes next. Simply, it is the neural balancing system located in your inner ear on both sides of the head or temporal region of the cranium. Its main function is control your skeletal balance, stability, and posture involving the vestibular organs of the utricle, saccule, and three semi-circular canals sensing your self-motion and gravity.
It is in the utricle and saccule of the inner ear that one finds the otoliths or calcium carbonate stones that tell your brain which is the way up as well as linear acceleration like when you jump up and down. The semicircular canals, on the other hand, sense circular motion and the accelerations involving spinning or doing cartwheels.
I know that some of you in the past have experienced an episode of “vertigo” at one time or another which is a form of dizziness producing a sensation of movement where there is none. But, it involves your vestibular and visual systems and the disagreement between their sensory input referred to as “sensory mismatch.” The otoliths of the utricle and saccule are most likely involved.
When experiencing an episode of vertigo, it usually is diagnosed as “Benign Positional Paroxysmal Vertigo” (BPPV). In many cases, the Epley maneuver is used that consists of a series of head movements to alter or change the position of the otoliths that will relieve the symptoms of BPPV.
However when the vestibular system functions as it should, it allows you to see clearly while moving because of a set of reflexes referred to as the vestibular-ocular reflexes (VOR), identifies your orientation with respect to the vertical force of gravity, determines the direction and speed of your movements, makes automatic adjustments in order to maintain your posture and stability, and adjusts your respiration and blood pressure through sympathetic reflex activity.
While on the surface it seems the vestibular system is responsible for a lot, its function is simply to answer two questions: where are you going and which way is up? Again, the primary concern of your CNS is your survival and keeping you safe. It is very important for you to know where you are going and which way is up so that you don’t hurt yourself and fall. The fear of falling is considered to be a high priority with your CNS and your brain.
The sum total of all this hierarchal, sensory input is the habitual posture, holding pattern of your body’s center of gravity (COG) that results in the habitual movement patterns you demonstrate with functional activities. As a result, your nervous system output is reliant on pattern recognition and prediction. Your CNS, your brain is designed to recognize a pattern of neural activation and how to respond in the right way for you to maintain skeletal balance and equilibrium.
Therefore In order to alter the output of your nervous system, I will use various head, neck, trunk, upper and lower extremity, and eye positions during exercise with the ultimate goal of changing the visual, vestibular, and proprioceptive input. I attempt to change your posture and movement, the output, by altering the sensory input.
Actually, all human change that occurs represents a change in the nervous system. That is because all that you are is derived from your CNS and the brain. Simply put, “You are your brain!” In fact, your entire existence, your memory of everything you experience while on your journey of life is merely the sum total of the electro-chemical firing of the neurons in your nervous system.
Your entire human experience as you know it can be diluted down to which of your neurons are firing, when, and how often. That’s your life! It’s all summed up into the electro-chemical activity of your nervous system. But one very important characteristic about your nervous system to keep in mind is that it has the potential and ability to change which is referred to as “plasticity.”
What a fantastic design! Contrary to popular belief, your brain does not stop developing at a certain age. You are constantly learning, adapting, growing, changing your entire life. Your nervous system is constantly taking in sensory input and creates an output. That is, until the nervous system shuts off with death.
When alive, we are not designed to be static, but instead are a dynamic process constantly moving and changing. Just watch a toddler. That is why, “Motion is Life!” As with most of your body, the phrase, “use it or lose it” is right on. That same phrase can be applied to your brain that should be processing a plethora of sensory input causing a motor output every second of every day no matter your age.
Since as mentioned most of your brain is dedicated to vision and movement, you need to move to drive the sensory and motor output loop of your nervous system. It is very simple, you move, you get sensory input fed into the system which is interpreted by your brain, you get a motor output, and then you move again and the cycle starts over.
Up to now, it has been all about the sensory input. But you can be sure that whenever there is sensory input, you will surely create a motor output. This nervous system output when it comes to posture and movement has two primary components: “reflexive stability and voluntary motor activity.”
The voluntary or volitional motor activity is controlled by the contralateral or opposite cortical hemisphere of your brain. This simply means the left side of your body is controlled by the right cortical hemisphere of your brain and vice versa. Approximately 10% of total output from your cortical hemisphere is dedicated to your voluntary or volitional movement.
Contrast that to 90% of your nervous system output pertaining to posture and movement is dedicated to creating reflexive stability of your structure located on the ipsilateral side or same side of your brain. It does this by activating through visual, vestibular, and proprioceptive sensory input part of the the “old brain” called the “pontomedullary reticular formation” (PMRF). The PMRF is responsible for controlling and maintaining your posture (holding patterns), setting your muscle tone, inhibiting sympathetic nervous system (fight or flight) tone, and inhibiting the sense of pain.
Whenever talking about posture and movement, I know you have heard me or some other allied health professional use the word “stability.” Simply, the stability of your skeletal structure at the isolated joint level or integration of the entire structure involves your nervous system output to the sensory input with the goal of achieving skeletal balance and equilibrium. You are balanced when your integrated body’s COG is vertically within the base of your support (BOS). If your COG happens to fall outside your BOS, you fall! It is as simple as that. The stability of your integrated skeletal structure is not only affected by your BOS, but also the position of your COG, your line of gravity (LOG), the horizontal force of friction, momentum, and of course the vertical forces of gravity and GRF.
With the eyes movements I utilize during many of the exercises I give you, you will close your eyes to eliminate the vestibular-ocular reflexes and facilitate these reflexes of stability by activating the PMRF on the same side of your brain. Conversely with the eyes opened, I will facilitate the vestibular-ocular reflexes and voluntary movement on the opposite side of your brain.
In all the exercises that I give you, keep in mind that I am trying to alter your nervous system loop of sensory input and motor output. Unfortunately, most health and fitness training systems as well as other allied health professionals focus primarily on the motor output. Something I also did for about the first ten years of my professional career. That is not to say that emphasizing just the output is wrong. However as I found out, you can’t change the dysfunctional neuronal patterns by focusing on the output. The electro-chemical activity of your nervous system that created your holding patterns and compensation in movement that is now causing your musculoskeletal inflammation and pain and eventual pathology can only be changed with altering the sensory input.
Your holding and movement, neuronal patterns are the result of this input-output communication loop of your nervous system. The holding patterns are the development of muscle synergies and fascial lines that are dependent on the position of your body’s COG. In movement, muscle synergies and fascial lines also develop from within the holding patterns. Simply if your holding patterns are dysfunctional, so will your movement patterns.
The development of your holding and movement patterns is a dynamic process that starts from birth. Each stage of your motor development is characterized by the development of specific, partial motor patterns which in the process represent an element of your mature motor development.
I know this can sound complex and confusing, but hang in there. In order to change what is happening to your body, you have to a foundational understanding of your nervous system. In the next newsletter, I will discuss this dynamic process in more detail and also the fascial lines and muscle synergy chains that you develop from this world of gravity and GRF. Until then, keep moving, because “Motion is Life!”
Terry