All About Balance & Joint Position Sense
Written by Justin Krull, Registered Physiotherapist
Stop what you are doing for a brief moment and close your eyes.
Place your arms up over your head and with the index finger of one hand, touch the tip of your thumb on the other. Did you eventually make contact? This is JOINT POSITION SENSE or PROPRIOCEPTION (The perception of self) and extends well beyond whether we can safely stand on a wobble board after spraining an ankle.
We begin to develop a sense of self from our first moments as we explore the world with our hands, mouths, feet, eyes etc. In fact, studies have shown that blind individuals still have accurate body images and people with congenital limb deficiency can experience phantom limb sensations, indicating that our internal body image may be partially encoded in the brain. Conversely, people who suffer from a negative body image such as Anorexia Nervosa have a disrupted awareness of the boundaries of their bodies. This extends to injury as well, which can disrupt our body image and cortical representation in the motor and somatosensory cortexes of the brain through neuroplasticity!
Dr. W. Penfield in 1951 was the first person to map out the cortical ‘Homunculus’ (The physical space on the surface of the brain responsible for the sensations coming from and motor signals going to each part of our bodies). Generally the size of cortical representation reflects the importance of signals going to or coming from each region to the extent that this ‘cortical real estate’ changes with focused awareness and attention. These neuroplastic changes occur when the brain pays close attention while learning. “Your brain – every brain – is a work in progress. It is ‘plastic’. From the day we’re born to the day we die, it continuously revises and remodels, improving or slowly declining, as a function of how we use it.” – Michael Merzenich, leading neuroscientist in the field of Neuroplasticity at the University of California, San Francisco.
The clinical relevance of Neuroplasticity is that the more often we are aware and sense and move in a specific pattern, (touching, walking, throwing, sit to stand) the patterns get merged in the Homunculus. This is positive if you are a violinist, golfer or a figure skater. However, this is negative if you are limping for a prolonged period of time after a knee injury or not moving and guarding yourself due to persistent low back pain. In fact, people with chronic low back pain have been shown to have markedly different cortical representation of their back when compared to healthy controls. This distorts the body map that the brain is relying on to execute movement which causes incompatibility between motor commands and sensory feedback which can produce pain and contribute to pain maintenance! This is one mechanism by which central sensitization of the nervous system occurs. By reversing this cortical distortion, the motor commands become compatible once again with the sensory feedback and pain from central sensitization alleviates.
Joint Position Sense is shown to be reduced in individuals with pain in the affected joint region. This can be a contributing factor to persistent pain, but retraining of joint position sense can help significantly reduce pain and disability. Research indicates that compared to usual strengthening exercises, proprioceptive exercises that involve precise repositioning tasks may have a greater positive effect on cortical reorganization. Awareness of the joint, movement with awareness in particular, appears to be the key to recovery with chronic pain sensitization.
How does someone train Joint Position Sense?
Simply close your eyes and consciously with full awareness move your head/neck (shoulder, ankle, knee, low back in sitting or standing, or whatever other joint it is you are trying to rehabilitate and desensitize!) in a 12 directional clock pattern several times per day. Don’t like clocks? Write a vertical or horizontal figure 8, your name in cursive, or the alphabet! Try keeping your head in neutral while gently twisting your body to the right and left as if passing a basketball, or gently swinging a tennis racket. Figure out the movements you like that are job or activity specific and perform those movements slowly with awareness. The important part is to just DO IT. Self-judgement and anxiety have no place in these exercise programs so never use a mirror for feedback with these exercises, and never force your available range of motion so you keep yourself safe. This program is incredibly beneficial after whiplash injury, concussion, low back pain, knee/ankle or shoulder rehabilitation, or for anyone trying to improve their physical performance.
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