Say Hello to the Vestibular System, one of the three most influential neurological systems in the entire brain.
A phylogenetically ancient system that can drive our parasympathetic state, it lowers our blood pressure, facilitates digestion, keeps us upright, reflexively fires our extensor muscles, and keeps us balanced.
This part of our brain evolved from our aquatic ancestors, and from sea to land we have evolved in an environment governed by gravity which has resulted in the activity of constant vestibular signalling.
Diagram representing the vestibular apparatus of the inner ear. 3 semi-circular canals, saccule and utricle that form the otolith organ and superior and inferior branches of the vestibulocochlear nerve (CN VIII) It transmits equilibrium and sound information from the inner ear to the cerebellum and temporal lobes respectively.
The primary function of the vestibular system is to transduce head acceleration into a signal the brain can interpret. As with any of the body’s senses, specialised receptors react to stimulus from the environment, pass the information onto the brain via nerve tissue and the brain ultimately transforms the information into something we understand and can respond to. For example, chemicals in the air become smells, pressure on the skin becomes touch and the stimulation of tiny hairs within the inner ear (vestibular system) becomes balance.
The orientation of the semi-circular canals (pictured above) make them perfect for recording various angular accelerations of the head and neck in space. The utricle and saccule which form the otolith organs record anterior, posterior and vertical translation of the head and body. When the system is working well, you have absolutely no awareness of its influence. If it breaks as in conditions such as Benign Paroxysmal Positional Vertigo (BPPV), dizziness, or vertigo, your interaction with the world will become unsteady, you’ll be nauseous and feel generally just wiped out.
The vestibular system communicates with the cerebellum 1 million times per second while at rest!
That’s a lot of information considering that we’re not even moving. Whilst in motion that number increases exponentially and one of the jobs of the cerebellum is to take this barrage of signals and modulate them so that appropriate muscle recruitment and control occurs.
Little Kid, Big Kid
As children, the sensation of dizziness is welcomed and even sought after. Kid’s love getting spun around and flipped upside down as the experience of dizziness is extremely short lived for them and is great because the stimulation of the semi-circular canals and otolith help to integrate and strengthen the intrinsic spinal muscles. In adults, however, something as simple as a forward roll may induce a far less pleasant sensation. Do a few forward rolls in a row or spin around in a circle a few times and you’ll see that while you may have stopped moving, the world doesn’t. Otolymph fluid within the Otolith Organ continues to swill around in the semi circular canals, telling the brain that you’re still in motion even though you are not. This means that the cerebellum needs a little more practice to attenuate this stimulus.
Please be aware though, that pushing the dizziness too far when first revisiting or learning complex movement patterns results in nausea and in some cases can lead to vomiting. Our inner ears are directly linked to our parasympathetic nervous systems (rest & digest). Drive that system too hard and blood pressure will drop, bowels may loosen and in extreme instances the title of this article could become an uncomfortable and awkward reality. I don’t need to tell you that having your clients poop, puke, and pass out probably won’t be getting you many referrals.
It has been shown in female Ballet dancers, when compared to female rowers of comparable age and fitness, that dancers’ brains have adapted to dealing with the onslaught of vestibular signals. It would appear that through years of training and practice, the pirouette (spinning) motion becomes a hard wired and pre-programmed movement pattern! Meanwhile, the cerebellum learns to negate the vestibular signals.
In the early stages of ballet training the cerebellum would have called upon multiple neurons to deal with the vestibular input. Over time, fewer neurons are required to transduce the signals, ultimately generating a far more efficient and less impactful (no dizziness) response to the stimulus. This process is referred to as neuroplasticity. With regards to sensorimotor tasks, as our skill level evolves to the highest degree it requires less and less attention from our cortical real estate.
Engaging in the process of learning complex movement has many benefits in the early unskilled stages. To ultimately specialise our skills, working towards a level of expertise is a natural evolution, leading us towards high levels of performance. Stepping out of one’s comfort zone and continually learning new skills is something that I’ve always found to be beneficial.
Back to Front
We have established that the vestibular system acts to inform the brain of the orientation and angular acceleration of the head in space, and is directly linked to our parasympathetic state. What should be of interest to all good trainers is the influence the vestibular system has over our muscles – and consequently over us being able to withstand gravity and stay upright.
Communication to and from the brain involve tracts that reside within the spinal cord. Ascending tracts carry sensory information from the peripheral to the central nervous system. Descending tracts carry motor instructions from the central to the peripheral nervous system.
In response to movement, the vestibular system sends reflexive motor commands via the vestibulo-spinal tracts to all extensor muscles which means: posture is reflexive!
Our posture is a dynamic balance between extensor reflexes, the brains inhibition of flexor muscles, and the flux of emotionally driven context. All things being equal – to maintain tall upright posture over the course of a lifetime our postural reflexes need to be stimulated. When we exercise we have a great opportunity to emphasise the activation of the vestibular system through our choice of movement.
Rolling movements on Gymnastic Rings, rolling work on the floor, spinning, bouncing, cartwheels, spin kicks and even crawling all strongly stimulate the vestibular apparatus and subsequently the cerebellum and extensor muscles. Get the dose and which direction to roll correct and you can quickly fix movement dysfunctions related to this system.
If you are currently unable to accurately assess vestibular function, there is evidence that gross, regular stimulation of the inner ear balance system has positive influence on health and function.
Note: While the following assessment won’t be perfect for everyone, some people don’t respond measurably to range of motion testing – the vast majority of you should notice a change.
Forward bend test:
Try this out – Stand with a tall spine, with your feet under your hips, toes pointing forward. Soften the knees slightly and slowly bend forward, gently reaching for the ground. Staying as relaxed as possible, stop the motion when you first feel a marked sensation of stretch, discomfort or general tension. These sensations can be anywhere but commonly in the lower back and hamstrings.
Having found the range of motion that indicates the current level of resting tension in your body, mark it with your fingers on your shins and remember how far you got. You could be really high-tech and mark the spot with a pen or something similar if you want, sometimes this is good to do with clients as it gives a more definite visual of any improvements.
Close the eyes and bounce up and down on the spot by performing quick and small calf raises. Maintain relaxed breathing and make sure the heels hit the ground rhythmically for about 10-15 seconds. If the body is kept relaxed, there should be a slight impact from the heels hitting the floor and a little shock that works its way up through the entire body.
Perform the forward bend test in exactly the same way as finding the baseline measurement.
Did you get further? Was your body more relaxed with less tension?
What just happened?
The otolith organs made up of the utricle and saccule are activated by anterior, posterior, and vertical translation. Bouncing on the spot with the eyes closed, preferentially excites the saccule. As such your extensor muscles, including the erector spinae were momentarily facilitated and sympathetic tone may have been reduced. The net result is a reduction in overall tension in the body and an increase in range of motion.
As ever with further information and more advanced assessments we could hone in on a particular semi circular canal and make this drill even more effective.
Rocking chair therapy
Yeah that’s right, Rocking Chair Therapy.
I have to admit this isn’t something I was aware of until recently and I’m sure it remains a fairly niche approach to treatment but none the less, spending up to about 1hr and day in a rocking chair has been shown to have some pretty powerful benefits for those involved.
This non-weight bearing, rhythmic motion has been shown to improve ‘autonomic tone’ in those suffering Chronic Fatigue Syndrome (CSF). By the same mechanism it has also been shown to dramatically speed healing in severely ill patients.
Dr Heinrich Addleheim of the Kinetic Therapy Clinic says that with regular rocking; “the body settles into a natural rhythm that harnesses incredible powers of recuperation and regeneration. We’ve seen cases of patients recuperating from heart attack and stroke – without any trace of permanent damage – simply because they used a rocking chair while they were recovering. I’ve seen people bedridden with arthritis who were up and around inside a week after regular use of the rocking chair. It can be used to cure colds, flu, diabetes and even some types of cancer. It’s not just a piece of furniture – it’s a remarkable medical device”.
A rocking chair provides non-weight bearing. Low intensity constant stimulation of the otolith organs. Over and above the specific stimulation of the vestibular system I am unaware of what other mechanisms may be at play here. The vestibular system has evolved in response to our environment and the governing force of gravity. While we understand the vestibular system our understanding of the exact effects of gravity on the body are, as yet incomplete.
I’m guessing that the idea for rocking chair therapy might have sprung from NASA’s research on the effects of rebound training utilising trampolines. In an effort to offset the havoc zero gravity plays on the health of astronauts, the Space Association research team discovered many incredible benefits of rebounding – bouncing on a trampoline (vertical translation – stimulation of the saccule among other systems), some of which cannot be matched by running or traditional exercise methods.
According to Dr. Joan Vernikos, research scientist and former director of NASA’s Life Sciences Division, even traditional strenuous gym workouts are ineffective at offsetting the ill effects of sitting.
“Medical studies on astronauts show that gravity-challenging, all-day movement is more essential to good health than traditional exercise” | Dr Joan Veernikos
In her work she refers to ‘the gravity vector’, interacting with gravity is essential to our health. As I have stated the complete answer as to ‘why’ is still at large but here’s some of what we do know:
The less we move the less we interact with gravity. The advent of modern technology that saves us from washing clothes in the river, washing the dishes and home cooking, hugely reduce the frequency of posture altering, gravity relevant movements that generations before us practiced as standard. Dr Joan’s work showed that the best thing we can do to offset the modern lifestyle is moving from sitting to standing! The more often you alter your posture to that of standing, the greater the effect.
From the very moment we are born, gravity is guiding the development of every single cell in our being. Efficient upright posture in standing is our reference point for all other movement. Gravity allows our brains to build maps based on the position of our head in space so we may always control and predict the safety of our own movements and to know where we are in space.
As gravity is a constant force our nervous systems have developed and are supported by what we may call ‘constant senses’. The constant sensory systems are muscle spindles and the vestibular system.
Muscle spindles are sensitive to stretch and thus react to movement. Via spindles within the chest wall, the action of breathing provides the brain with the constant baseline information necessary, even when we are not in motion:
- O2 stimulates mechanoreceptors in the chest wall
- Gravity acts on gravo-receptors and muscle spindles
- Vestibular system provides constant reference to gravity
The constant senses actually support function of the non constants; Sight, sound, smell, touch and taste. How we move, or rather how we don’t move can actually effect the quality of our sight, hearing, proprioception and smell but that’s a topic for another article.
I would hope that if nothing else this article ignites enough curiosity for you, as a trainer or therapist to investigate the amazing inner ear in more depth. To think how you can optimise the time a client spends with you as you guide them through exercise or rehabilitation.
We are fascinatingly complicated creatures. For all of its benefits… Modern living is dumbing our senses, our ability to move, and ultimately negatively impacting our health. Begin to learn how the body works and you will start to move in more stimulating ways.
Cullen. E Kathleen. Mini review article. 13/01/14. The neural encoding of self generated & externally applied movement: Implications for the perception of self motion & spatial memory
The Neuroanatomical Correlates of Training-Related Perceptuo-Reflex Uncoupling in Dancers
Yuliya Nigmatullina1, Peter J. Hellyer2, Parashkev Nachev3, David J. Sharp2 and Barry M. Seemungal1
James. E Clara. Oechslin. S Mathias. Vandeville. Dimitri. Hauert. Claude-Alain. Descloux. Celine. Lazeyras. Francoise. Musical training intensity yields opposite effects on grey matter density in cognitive vs sensiromotor networks. Brain Structure Funct. July 2012
Beck, Randy W, Functional neurology for practitioners of manual medicine, 2nd edition, 2011, Churchill Livingstone Elsevier
Carrick Institute. 800 series lectures, modules 801-808 audio series
Journal of Applied Physiology 49(5): 881-887, 1980. Journal of Applied Physiology 49(5): 881-887, 1980 at http://jap.physiology.org/content/49/5/881.abstract.