We’re all familiar with the five senses: sight, hearing, smell, touch, and taste. But did you know that there is a sixth sense? That may sound supernatural, but it isn't. Enter proprioception, the perception and awareness of the position and movement of the body.
Can you close your eyes and touch your nose? Proprioception facilitates the ability to accurately complete a movement without any visual or tactile input.
In today's article, you'll learn about the physiology of proprioception and how to improve this sense to prevent falls and fractures.
Proprioception Through The Ages
When Aristotle defined the five senses he pointedly excluded a sixth sense- perhaps in part because there was no clear sensory organ that gathered information about the body's position and motion. We smell with our nose. We feel with our skin. We see with our eyes. But what part of our body tells our brain where our body is and how it is moving?
This question has been at the heart of the study of proprioception for centuries. In the 17th century, early scientists speculated about a “muscle sense” that created proprioception. In the 1800s, German theorists posited that proprioception occurred entirely within the brain, and no signals or information were sent to the brain from the body. They speculated that when the brain sends the impulse for movement to the limbs, it sends a copy of the instructions to a different part of the brain that creates an understanding of where the limbs are in space.1
That theory was proven insufficient by the simple fact that we know where our limbs are even when they aren't moving. The discovery of proprioception as we now understand it is credited to a scientist named Charles Bell, who wrote about the ability of muscles to communicate their movement and position to the brain.2
Contemporary technology has allowed for closer study of the mechanisms by which we sense where our body is in space, either still or in motion. Experiments conducted using MRIs and virtual reality have revealed the complexity of proprioception- proving that nerve endings in the muscles are assisted by additional nerves in the joints, tendons, and skin, as well as our ability to see ourselves.3
Proprioception was misunderstood for many centuries. Some scientists mistakenly thought the body did not send any information to the brain about its position- and others were wrong about the origin of the signals. But fortunately, contemporary technology has unlocked many of the secrets of proprioception.
Proprioception As We Now Understand It
Proprioceptive senses include several physical senses: the senses of position and movement of our limbs and trunk, the sense of effort, the sense of force, and the sense of heaviness. These senses combine to provide us with a mental image or understanding of the physical actions and positions of the body and to create physical stability and balance.
Receptors involved in proprioception are located in the skin, muscles, and joints. The majority of the receptors are scattered throughout skeletal muscle in special pockets called muscle spindles. These capsules of connective tissue contain specialized muscle fibers called intrafusal fibers that are equipped with nerve endings. The muscle spindles provide your brain with information about the contraction of muscles- both in stillness and in movement.1
This function was proven when scientists discovered that they could create a false signal by vibrating muscles at specific frequencies- causing participants to report movement when their limbs were actually stationary.4
However, the brain's ability to precisely sense position, effort, force, and heaviness, and to accomplish balance and physical stability indicates other sensors. Indeed, other experiments have shown that the brain gathers information about movement from sensations experienced in the skin and joints.5
Our eyesight also contributes to proprioception. When we see our body, this additional layer of information confirms and refines our physical proprioceptive sense. By comparing the two sources of information (physical and visual) our brain knows that the limbs it sees are the same limbs that it feels.6
Together, these tools for amassing information give us important abilities. Proprioception makes it possible for us to turn on a light switch in the dark, to navigate around known objects without looking at them, to maintain physical balance, to avoid obstacles, to assess the weight of objects, to apply an appropriate amount of force to complete a task, and many more actions.
Proprioception includes the ability to sense our position and movement, effort, force, and heaviness. Receptors in the skin, muscles, and joints all provide information to the brain about these sensations. The majority of receptors are found in pockets of special tissue in the muscles called muscle spindles. Sight also contributes to our understanding of where our body is, and our designation of what is and is not part of our body.
Proprioception, Stability, And Falls
Like our other senses, proprioception is facilitated by body parts that are affected by aging, the most significant of which is muscle mass. Proprioception typically declines with the loss of muscle mass (sarcopenia) that accompanies aging.7
Proprioception is a critical determinant of standing stability- which helps you maintain your balance and avoid falls. Consequently, with the age-related decline of proprioception, there comes a reduction in standing stability and an increase in the risk of falls.7
Fortunately, studies with older people have found that interventions that provide targeted physical exercises can improve proprioception and subsequently reduce the likelihood of falls. A 2015 study of eighteen older adults found that strength, postural stability, and proprioception sensitivity were improved through eight weeks of thrice-weekly physical training.8
You can apply the lessons learned in this study and others like it by incorporating exercises focused on improving stability, balance, and lower body and core strength into your workout routine.
Start by doing this exercise which is specially designed to increase proprioceptive sensitivity and balance while strengthening the ankles, feet, and core muscles:
Proprioception worsens as muscle mass and strength decrease with aging. This results in reduced standing stability and balance and a higher likelihood of falls. Exercise designed to improve stability, balance, and lower body strength can preserve proprioception and reduce the risk of falls.
Develop Your Senses And Strengthen Your Bones
Proprioception is yet another physical attribute that you can actively improve through regular exercise. In addition to the direct stimulation of new bone growth and an increase in muscle strength, targeted physical activity is a baseline necessity for improving bone health and preventing fractures.
The exercises in the Save Institute's workout program Densercise™ are designed to provide precisely what your bones need- improving muscle strength, bone health, and your proprioceptive senses. Densercise™ also includes an eating guide and an online collection of videos to lead you through the bone-building movements.
Sharpening your proprioception through regular exercise will improve your ability to move through the world with stability and certainty.
Take Exercising For Your Bones to the Next Level!
Learn the 52 exercise moves that jumpstart bone-building – all backed by the latest in epigenetics research.