We usually don't think of our bodies in terms of their being "smart." For example, we walk to the corner store without giving a single thought to the complex mechanics involved in getting there and back. But behind the scenes there's plenty going on and your body's "IQ" has a lot to do with your success in accomplishing everyday tasks.
Proprioception is one of those background physical processes that make up your body's total IQ. Proprioceptors are specialized nerve endings located in your muscles and joints that inform your brain about your body's position in three-dimensional space. You're able to write legibly because proprioceptors are sending instantaneous data about the angles of the small joints of your fingers and wrists as your pen moves across the page. You're able to run on the beach because proprioceptors are continuously sending signals to your brain about the changing shape of the uneven surface of the sand.1
Without these specialized nerve endings, we'd never be able to hit a baseball, throw a Frisbee, or drive a car. But proprioceptors can be smart or less than that. It all depends on how well-trained they are. One person out for a stroll might trip over a crack in the pavement and suffer a badly sprained ankle. Another person might trip over the same crack, even badly turning over their ankle in the process, and keep on walking without even a trace of a limp.
The difference between injury and non-injury is the level of proprioceptor training, and this level usually is related to whether you're doing regular exercise.2 Exercise trains your muscles and joints to adapt to varying kinds of stresses (weight-bearing loads) throughout a variety of positions (the full range of motion of those joints). As a result, trained proprioceptors can withstand a high degree of stress (such as a sudden twisting of an ankle). The untrained ankle, possibly the ankle of a person who hasn't done much walking, running, or bike riding in the last 5 years, will be damaged by an unusual and unexpected stress. The result is an ankle sprain of varying severity and possibly a broken ankle.
Similarly, it is well known that older adults experience more frequent falls than do younger adults. Part of the explanation involves proprioception.3 Many older adults don't engage in regular exercise. Proprioceptive function decreases, changes in level or surface aren't recognized quickly by the person's feet and ankles, and the person falls.
It's easy to see that the effort to maintain your body's IQ is time very well spent. The fastest way to boost this skill set is by doing regular exercise. All kinds of exercise provide benefit, so the best exercises are the ones that have some interest for you personally. Optimally, a person is doing both strength training and cardiovascular exercise. As always, the key to long-term health and wellness is consistency.
1Wong JD, et al: Can proprioceptive training improve motor learning? J Neurophysiol 2012 Sep 12 [Epub ahead of print]
2Ferreira ML, et al: Physical activity improves strength, balance and endurance in adults aged 40-65 years: a systematic review. J Physiother 58(3):145-156, 2012
3Howe TE, et al: Exercise for improving balance in older people. Cochrane Database Syst Rev 2011 Nov 9(11):CD004963.