"Don't think, Feeeeeel! It is like a finger pointing away to the moon. Don't concentrate on the finger or you will miss all that heavenly glory."
~ Bruce Lee in Enter the Dragon
Proprioception is elegant in it's simplicity and yet gives rise to one of the most complicated and profound phenomena in our human experience. Proprioception creates the experience of embodiment. It frames the parameters by which we understand our relationship with the outer world. It may well be a significant component of consciousness. While the above is the realm of neuroscience and philosophy one thing we know for sure is that without proprioception it would be impossible to navigate the world safely.
But how does it work? Distributed throughout muscle, joint & skin tissue are tiny receptors that measure subtle mechanical changes like stretch, amount of tension and pressure. These sensors are linked through the vast network of the central nervous system which communicates information about the state of the tissues in the body to the spinal chord and from there on to the brain. Specifically this information is processed in a part of the brain called the Cerebellum. Folded like an accordion the tissue of the cerebellum is densely packed with neurons in a small space enabling it with a large processing capacity. Located at the base of the brain very close to the main channel of communication with the body, the brain stem, the cerebellum is largely responsible for motor control. Out of a constant cacophony of signal from receptors throughout the entire body the Cerebellum recognizes patterns, interprets them as joint positions and creates a mental map of how all the various parts of the body are oriented in space. We experience this process as the sensation of our bodies in space and the feeling of movement.
To understand proprioception it can be helpful to visualize it on a small scale. Visualize an individual muscle in your arm. Contained within that muscle tissue are many very tiny mechanoreceptors. These sensors measure and transmit information about the amount of stretch the muscle is experiencing. If you can picture a coiled wire you are not far off the configuration of the protein that resides inside the mechanoreceptor. When the muscle stretches because the arm is contracting while holding something heavy the coiled protein inside the mechanoreceptor stretches as well. The mechanoreceptor then sends a signal through the central nervous system to the cerebellum saying "hey! Were stretching X amount." This message in combination with all the other sensory information is processed and interpreted by the cerebellum to very accurately predict the position of all the joints in real time giving rise to our sensory experience of body position and motion.
Proprioception not only helps guide movements but contributes to our sense as well aided with two other important systems. These are the visual motor system and the vestibular systems. If your not familiar with how the visual motor system aids in balance and situational awareness while performing sports I highly recommend visiting the website eyeQ.com and learning about Dave Picket's fascinating and extensive work on the subject. The Vestibular system is something you will have at some point in your life become acutely aware of if you have ever become dizzy from spinning.
Located in the inner ear are fluid filled rings internally lined with small cilia hair like projections attached to sensors. Depending on the orientation of the head the fluid will move and the brain is generally very good at interpreting the stimulation patterns created by the moving fluid to inform balance. When we we spin and suddenly stop the fluid continues to move with the momentum of that action for a short period of time. The brain thinks you are still spinning but this conflicts with the eyes telling the brain that the spinning has stopped. This conflict in communication between the two systems is experienced as dizziness. With practice anyone can become more accustomed to these mixed signals, figure skaters for example, who practice high speed spins repeatedly report no longer experiencing dizziness as the brain has adapted to the conflicting sensory information over time.
Proprioception is so ubiquitous to our experience of reality that we can completely take for granted that it is happening all the time subconsciously. Right now you know where both your right and left big toes are in space regardless if you can see them because you feel where they are. Try this experiment. Massage just the right toe for one minute. Then observe the difference in sensation between your two big toes. Because you have stimulated mechanoreceptors in the right big toe the neural pathway for the right big toe has been activated and the proprioceptive sense for that part of the body awakened. You will feel your right big toe more acutely than your left for a short period of time.
Motor Sensory Amnesia
Conversely there are situations where proprioception can be weakened and our mental map of our bodies in space made more vague. This is called motor amnesia. The first instance where this takes place is simply with lack of use. If you were a really active child skipping rope and swing from monkey bars as easily as walking down the street but in your adult life you have become primarily sedentary trying to repeat those movements will feel a little robotic and malcoordinated at first. If you were to pick up those activities again however and practice them diligently for a few days the same neural pathways from proprioceptors to cerebellum would be re-strengthened and you would restore your youthful grace in those movements all it would take is time and practice.
The second situation where our mental map can be distorted and our ability to perform movement efficiently impeded is when we sustain an injury. Pain combined with an effort by the body to stop using the injured tissue so it may heal literally atrophies it's sensory neural pathways. A commonly explored example of this is spraining the ankle joint by rolling over the outer edge of he foot. The injury to that tissue is compensated for by the other foot for a period of time and the sensory system that communicates to the brain the position of the injured ankle joint is weakened over time. It is quite likely without substantial effort to rehabilitate this injury completely the joint will be prone to a repeat of precisely the same injury due to motor sensory amnesia. It becomes a vicious cycle of injury leading to reduced ability to sense that part of the body making it vulnerable to injury yet again and so on.
The case of motor sensory amnesia that I see the most often as a Ski Instructor and Yoga Teacher is that which arises from joint range of motion limitations. If the muscles surrounding a joint are excessively tight and impede the joint from moving through it's full range there are receptors within the tissues of the joint that will never be stimulated leading to black spots in the mental map. Tight people literally can not feel the entirety of their bodies. They don't know what they are missing.
This is what Mr. Lee was talking about in Enter the Dragon. "Don't concentrate on just the finger or you will miss all that heavenly glory." In the same way, don't concentrate exclusively on strengthening just the parts of the body that are considered most important in your particular sport and neglect stretching those same tissues as well as strengthening and stretching all the other parts of the body. Not only will you blind yourself to the full extraordinary sensory experience your body is capable of. You will cripple yourself from being able to quickly learn, internalize and refine new movement patterns. You will miss all that heavenly glory.
Kinesthesia & Learning Movement in Sport
When it comes right down to it skiing, like all sports, is about learning to feel body movements that produce desired outcomes so they may be repeated. Enter the process by which we learn how to perform movement patterns for the first time and store that memory for future use. The eighteenth century physiologist and neurologist Henry Charlton Bastian first gave this process a unique name calling it Kinesthesia. This term describes our conscious awareness of the sensations associated with performing movements.
A good example of Kinesthesia at work was when I finally learned how to ski with a stance that was appropriately wide. I remember it had a recognizable sensation. I felt it mostly in my hip muscles and described it as uncomfortable. Really it was just foreign. I was stimulating mechanoreceptors in a novel pattern and it was completely new and slightly awkward. The consequence of that body position was that my turns felt more stable. Once I knew those key target sensation, the discomfort in my hips, and the sensation of a more stable turn as if by magic I could suddenly recreate that more aligned stance at will.
As a teacher of movement I still marvel at these eureka moments when I witness my students having them. A student has a unique combination of learning style, cultural influences, body configuration and life experiences that influence her interpretation and communication of movement sensations or movement vocabulary. This can vary widely between students and event day to day or moment to moment within one student. Therefore, as a teacher of movement I have necessarily become a part telepathic and part movement linguist. Like most sport instructors I fortunately poses a Rosetta stone of movement vocabulary. I acquired it during thirty years training in various movement disciplines combined with a strong ability to empathize with students and many many hours carefully observing student responses to different instruction.
However, I know enough know to know that I am just a guide in the loosest sense of the word engineering the conditions for learning to take place. Ultimately the student must experiment with information I give her in the environment until they stumble upon the sensation for themselves and define her own movement vocabulary. It is a challenging art to be a teacher who can create the right blend of environment and instruction at the right time to guide a student towards the right epiphany. As a student it is equally challenging
Often kinesthesia and proprioception are used interchangeably. It is important to understand that while operating from a common mechanism they are not the same thing. Kinesthesia is a behavioral process. It has to do with learning movement. It corresponds with things like developing muscle memory and hand eye coordination. Proprioception is largely automatic and unconscious. It describes our sense of our bodies in space and informs our sense of balance.
Kinesthesia and learning movement
Kinesthetics sense can be with practice or allowed to weaken with disuse. Kinesthesia is how we learn movement patterns that are effective for helping us achieve certain outcomes for example learning how to swing a bat to hit a ball or how to navigate a mountain by turning skis on snow. Performing basic movements while reflecting on their corresponding sensations of the movement connect you into a rich sensory scape where physical literacy is gained. Learning how to pay careful attention to sensations associated with movement is one of the hallmarks of yoga practice.
Tapping into the four parts of the foot
In yoga asana practice one of the foundational standing postures is Tadasana or Mountain Pose. How appropriate for a discussion about yoga for skiers to reflect on the many benefits of Mountain Pose. The posture itself involves simply standing with feet parallel and hip distance. The goal is to stand with perfect posture so the breath can be full and unrestricted. Outwardly it appears incredibly simple and yet internally there is a lot going on. When teaching this posture I give many alignment cues from the ground up.
The first cue is to become aware of four key points on the bottom of the feet. These are the distal end of the 1st metatarsal or the fleshy mount just back from the big toe, the distal end of the 5th metatarsal or the fleshy mount just back from the pinkie toe, as well as the inner and outer edge of the Calcaneus or the heel bone. If there is even pressure on these four points chances are the rest of the body above the feet is aligned.
The second cue is to broaden the toes. The purpose of separating the toes is it makes more pronounced the sensation of pressure on the 1st and 5th metatarsals helping the practitioner tap more into their kinesthetics sense to find balance. All the remaining cues are to activate specific muscles that will support and strengthen that beautifully aligned posture.
Most yoga practices start with a series of linked postures called Surya Namaskara or Sun Salutations. Pose number one in the sequence is Tadasna, Mountain Pose. I marvel at the elegance with which the ancient yogis crafted this practice. Mountain Pose is the perfect kinesthetics sense builder. Starting the sequence with this posture helps the practitioner tap into sensing the alignment of their bodies through the litmus test of feeling even pressure on the four points of the feet. It primes them to become more receptive to sensations arising in the body that inform alignment to create effortless balance.
So to in skiing there is a specific point on the feet that we want to pay attention to but it is even smaller. Ski Instructors often refer to this spot on the foot as the front of the heel the back of the arch. It is the intersection of four bones in the feet which are the Calcaneus, Cuboid, Navicular & Talus. A circle, approximately the size of a quarter, marks the sweet spot of the foot. I have a custom footbed in my ski boot with an arch support that helps me feel this spot on my foot.
Feeling pressure on the sweet spot of the foot is the result of bending and extending the hip, knee and ankle joints to precisely the correct degree and in the right order. The result is that the body weight lands right on top of the sweet spot of the ski, just back from the mid point in-between the toe and heel pieces of the bindings. When this happens the ski turns almost effortlessly. Voila! Just by learning to feel pressure on a specific point of the foot aligns the body creating balance. With balance all things become possible.
Next Week: Experiments in kinaesthetic training: My first pigeon pose I thought I was going to die