I've been seeing this term pop up lately in like in this question about measuring balance, but I'm not familiar with what it means. There's a tag for it which has no wiki summary. What does this term mean, and what is its relation to exercise? Why would I care about it?
Proprioception = Position Sense. It is the internal awareness of the body’s position and posture. Receptors in the body, such as proprioceptors in the muscle spindles or tendons as well as the ear’s labyrinth, receive information about joint position, pressure or stretch and provide feedback. This sense allows you to close your eyes and still know where your body parts are in space. Without this kinesthetic sense, you would not be able to maintain your balance with your eyes closed, or tell if your knee is bent or straight unless you look at it.
Why is proprioception important to fitness and exercise?
The better your proprioceptive sense, the better your joints can adapt to changes in position, such as running on uneven surfaces. Proprioception is not an all or nothing sense. Instead there are degrees of sensitivity and accuracy. Proprioceptive senses can lessen with aging or injury and can improve with neuromuscular training.
Why should you care about proprioception? Good proprioception is important in balance, agility, athletic performance and injury prevention. If you have sprained an ankle for example, your ankle joint’s proprioceptive sense is reduced (unless you have specifically rehabilitated to regain that awareness). This makes your ankle, and the muscles surrounding your ankle, less efficient and more prone to re-injury. To improve your proprioceptive sense try exercises such as one legged standing balance with and without movement, with eyes open and closed, toe or heel walking and balance on a wobble board or BOSU.
the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement.
Essentially this means you know where each part of your body is without having to see it - so if you close your eyes, you're able to touch your nose even though you can't see either your hand or your nose.
I haven't come across anything relating to proprioception in fitness - it's an innate sense (like touch).