Proprioception: the Sixth Sense

Close your eyes and balance on one foot.  If you do this, you’ll notice that your muscles will contract and relax differentially and repeatedly as an attempt to help you maintain your balance.

Why does this happen?

It is a process that is controlled by a 6th sense we all have. This is called proprioception. (Note: we actually have many more than the “5 senses” we are commonly said to possess.)

What is it?

It’s an interesting sense, because we don’t necessarily pin a specific sensation to it, and we can go throughout our day without recognising its existence. It is a subconscious feedback mechanism that triggers muscles to contract and relax, without conscious effort, in response to a specific stimuli.

Proprioception allows us to walk or run or pedal without having to watch our limbs as we do so. If it didn’t exist, we would find it to be impossible to run without watching our feet during each and every step! When learning to move properly, one of our objectives should be to familiarise ourselves enough with a movement that we no longer need purposeful focus on the movement pattern.  It’s something that naturally happens as we use muscles and practice skills, and there are many examples of proprioception at work which I’m sure could be thought of if we tried to create a list. In fact, without proprioception in my hands, I wouldn’t be able to type this without looking down at my hands constantly to ensure my fingers are reaching the proper key.

How it works

Exercise scientists actually are not one hundred percent certain about the mechanism of proprioception.  It is understood, however, that sensory receptors (proprioceptors in this case) send feedback to our brain based on stimulation of the receptors.

Proprioceptive messages travel from receptors through the central nervous system to the rest of the body forcing it to react by increasing or decreasing tension in certain muscles.   One of the signals that acts on these proprioceptors is gravity, and they are even involved with maintaining your posture both as you move, and whilst you remain motionless.  Another example of this sense at work would be stepping down off of a curb and having your foot land on a small rock, if everything was working properly you would unconsciously adjust tension in that leg and foot so that you do not sprain your ankle.

If you did sprain your ankle, though, that would be bad news for your sixth sense.

We can actually lose proprioception just like we can lose other senses, and this often occurs when there is an injury (though I suspect disuse can cause this as well). Injury can damage muscle, joints, ligaments, and the sensors and nerves in the area, which can inhibit their ability to send a feedback signal through the central nervous system. In fact, it is known that people with the highest risk for spraining their ankles are the ones who have experienced a sprained ankle already. If we think about why this might be:

  • We step onto an uneven surface and our foot pronates quickly and unexpectedly causing a sprained ankle.
  • We lose proprioception in that ankle and the feedback mechanism for the next time we step on an uneven surface is damaged, and does not get rehabilitated.
  • We step on an uneven surface again, and cannot react quickly enough (due to damage to proprioception) to adjust pressure on that leg, and are unable to prevent an additional ankle sprain.

Since it is known that when a person sustains an injury they can lose proprioception in the related area, an understanding should follow that we can gain proprioception by specific training/re-training. It is similar to flexibility and strength in that if you work on it, it can get better.

There is reason to believe that slow-twitch muscles provide better proprioceptive feedback to the nervous system than fast-twitch muscles do.  This makes sense when we think of fast-twitch muscles being prime movers and slow-twitch muscles functioning more-so as stabilizing muscles.

I take from this that training for proprioception should be done using situations that involve high sensory input and slow-twitch muscle activation.

hiking

Since I am primarily discussing running, I will provide a means for improving proprioception in the feet and legs.

I think that one of the best ways to improve proprioception in your feet and legs is to hike trails in minimalist footwear.  It is a slow movement as was mentioned above to be an important factor in the development of proprioception, and the low amount of padding on our feet in this footwear would allow for an improved ability for the many sensory nerves in our feet to turn on and send feedback through our muscles.  Additionally, if on our hike we happened to balance slowly across a log, I think that would likely help our cause!

I think it is an important athletic component that is often under-considered.  Understanding that we have this sense gives a new level of confidence and control in our movement. It allows easy, thoughtless adaptation to our surroundings. On a trail run, this helps us to focus on things that may matter more than watching our feet, like breathing properly, or keeping an eye out ahead and picking a line to follow, or telling ourselves that we’re not actually dying and that it’s okay to continue.  I think proprioception becomes increasingly important as we fatigue.

I see proprioception as one of the most important aspects of athleticism and injury prevention, and something that more people should be aware of.

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2 responses to “Proprioception: the Sixth Sense

  1. I have been delighted to discover recently that after three years of barefoot/minimal running, my body pulls my foot out of a bad situation (such as rolling an ankle) before it occurs. A glorious thing to see what happens when we get out of the way and let our body do its thing.

    • It is the ultimate confidence boost to realise you possess this unconscious skill. To understand that your body will react to your surroundings faster than you could consciously if you let it learn how is such an unrealized potential by many.

      Glad I’m not the only crazy one that’s experienced this!

      Thanks for sharing, Karen.

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