Two Big Words Worth Knowing
WHY are these words important?
1. They are the systems that inform our brains about the internal state of our bodies, muscles and joints.
2. Without this information our brains cannot accurately direct our movements.
3. Apart from their crucial role in movement, they also impact our mood as well as our state of wakefulness.
WHAT ARE THESE SYSTEMS?
They are the hidden senses of the VESTIBULAR and PROPRIOCEPTIVE systems. (The two big words!). They are hidden because they operate subconsciously so that we are mostly unaware of them.
While everyone is easily able to name the 5 special senses of touch, taste, smell, sight and hearing, these two hidden senses are less known, but equally important for human functioning.
Although they are two distinctive systems, they work together as well as with the sense of touch.
1. They allow us to balance
2. They tell us how much force to apply or how far to move in space
Too much force and they break; too little force and they stay in the tray
Too far or too close will miss the rock
3. They keep us upright and they maintain muscle tone
4. They enable us to learn and perform complex skills
5. They wake us up and give us a feeling of enjoyment and excitement (or terror!)
3. They calm us down and help us sleep
HOW DO THESE SYSTEMS ACHIEVE THIS?
When their receptors are stimulated, they send messages to:
- The sensory areas of the brain which is then able to interpret this feedback and adjust or refine movements as necessary. These adjustments are stored in our memories so that comparisons can be made next time we perform these movements.
We sometimes hear people talking about “muscle memory”, but memory of movement is not actually held in the muscles. Movement memory is held in the basal ganglia of the brain in the form of motor “engrams”. New engrams are formed and new circuits are developed when learning NEW sequences of movement or complex tasks.
- Other areas of the central nervous system including those modulating levels of alertness as well as those involved with timing and speed.
WHERE ARE THESE RECEPTORS?
VESTIBULAR receptors are found in the inner ear, adjacent to the cochlea, which is the receptor for sound.
They are stimulated by:
- Any movement of the head
- Gravity when the head is static
- Acceleration of the whole body or deceleration (eg sprinting or going down a slide)
- Slow rhythmical movements
PROPRIOCEPTIVE receptors are found all over the body, imbedded in every muscle (muscle spindles) and in tendons (golgi tendon organs).
They are stimulated by:
- ACTIVE movement of the muscles
- Resisted movement against gravity or using weights.
Muscle spindles send constant feedback to the brain regarding the state of tension in the muscles and the orientation of the limbs in space. They are most numerous in areas which require precision and speed of action, such as the muscles in the hands.
As with every other sense and system in the body, these two systems deteriorate with age, but especially through a sedentary lifestyle.
The RESULTS of NOT MOVING?
- Reduced balance and increased risk of falling
- Reduced judgement of force and distance
- Reduced postural extension and ability to remain upright against gravity
- Reduced ability to learn complex and new tasks
- Reduced mental alertness and higher risk of depression
- Reduced sleep and increased anxiety
Movement does not just happen in our muscles and joints. It is a complex system known as the SENSORY-MOTOR system, with the brain as the interface between the two. In order for the brain, as the command centre, to activate movement, it requires feedback from the body and limbs. However, feedback from the body and limbs is stimulated by movement. And so the cycle of both movement and feedback contribute to the ongoing stimulation and health of the brain.
Maintenance of the health of the vestibular and proprioceptive systems requires movements that are varied (in terms of type and speed) and those that incorporate all muscle groups. By learning new sequences of movement, the brain develops new circuits and is kept alert and active.
With the proximity of the cochlea to the vestibular system, incorporating music with movement makes a perfect combination for a comprehensive and enjoyable body and brain workout with additional vital benefits to mood, mental health and sleep.
FITNESS LEAGUE CLASSES OFFER ALL OF THE ABOVE. No need to say more!!
Susan van Ryneveld
Occupational Therapist (since 1981)
Sensory Integration lecturer (since 2001)
Fitness League teacher (since 2018)