Proprioception - the real 6th sense
Proprioception aka “joint position sense” is the body's sense of its position relative to its environment e.g if we wave our hand above our head we know where it is without looking at it, and in the foot's case, it is what gives us an “instinctive” sense of where it is relative to the ground. There is a constant stream of information from the foot to the central nervous system as to what's going on underneath it, this is processed, and information is sent back down to the foot as to how to keep us upright. (The other two input mechanisms of balance are our vision i.e. maintaining a horizontal horizon, and the "internal gyroscope" we have in our inner ears.)
Deficiencies in proprioception can lead to overcompensation and pain in the limbs and the lower back in sport or even in activities of daily life. For example: A recreational “once a year” skiier or snowboarder is challenging their proprioceptive system to the maximum due to going from the norm of walking or running on a flat surface to sliding on a sloped, uneven surface. The body invariably attempts to cope with this new and increased demand by creating a false sense of stability, stiffening the muscles of the legs and (in my own case) gripping with the toes which is both highly energy sapping and the complete opposite of what you need in sport where fast adjustments are necessary.
As the day goes on and the proprioceptive system gets a bit of practice, the symptoms may subside, but as one fatigues towards the end of the day the symptoms can return as the limb defaults back to the lowest common denominator way to regain (false) stability, rigidity and toe gripping. Similarly, in poor visibility, visual input to balance is removed hence heaping even more demand onto the proprioceptors so.... more rigidty and toe gripping. This creation of false stability is very common in many sports and everyday life e.g. in many cases of muscular back pain the root cause is actually insufficiency of proprioceptive input/output from the muscles of the limbs, pelvis or torso forcing false stability through overuse of the back muscles. So what's the solution?
"Practice" would seem the obvious answer but you would be surprised by the number of elite athletes who have pain due to this issue and find it very difficult to break the habit of overusing the "wrong" muscles for the job, often resulting in a brick wall to improvement in their sport. In everyday life e.g. walking, running, sitting at a desk, lifting, it's not as if we haven't practised these actions, we do them every day, but still they cause pain!
In both of these types of case a bit of detective work is required, as the issues vary from individual to individual. I resolved my own foot pain when snowboarding by identifying insufficiencies in the way my back, hip joint and leg muscles reacted to uneven surfaces, hence allowing better input to/output from the muscles, joints and nervous system. The foot was essentially the "victim" but the "criminals" were further up the body. You don't have to be doing vigorous sport however to train the proprioceptive/balance system there are more gentle means to improve this in everyone of any age. For example there is good evidence to suggest that regular practice of tai-chi reduces senior citizens fracture risk through falls.
