By Angelyn Frankenberg   Feb 16, 2015   From the Post Independent/Citizen Telegram

Test your balance by standing on one foot with your arms crossed in front of your chest and raising one leg so your foot is near but not touching your other ankle. How long can you hold the position? The average durations by age group are: 40-49, 42 seconds; 50 to 59, 41 seconds; 60-69, 32 seconds; 70-79, 21 seconds. If you are 50-plus and physically active, you probably will experience better-than-average duration.

Now try the same test with your eyes closed. Even if you are very active — unless you start your day with balance beam gymnastics or a unicycle ride — do not be surprised to find your time is not above average for your age group: 40-49, 13 seconds; 50-59, 8 seconds; 60-69, 4 seconds; 70-79, 3 seconds.

Maintaining a good sense of balance is a cornerstone of successful aging. It helps prevent falls and the fear of falling and contributes to a general sense of well-being, of feeling at home in one’s own body. Balance involves a complex interplay of physical and mental factors but depends on three sensory components: vision, the inner-ear (vestibular) system and proprioception, the subconscious sense of movement and position. For a detailed look at all three systems, see Scott McCredie’s “Balance: In Search of the Lost Sense.”

Differences in balance time on one foot with eyes open and eyes closed are not surprising because vision is the sense we depend on and trust the most. But what about the other sensory inputs? Most of us have at least a basic idea of the workings of the inner ear (vestibular) system, but proprioception is relatively unknown outside of scientific circles.

This hidden sense, which is related to touch but operates at a subconscious level, depends on specific structures in our muscles and joints and at muscle-tendon junctions. Proprioception senses changes in position in space, limb movement, pressure, and the degree of contraction or relaxation in muscles. Besides contributing to postural stability, it allows us to apply the right amount of force or pressure for a particular task.

Maintaining a good sense of balance is a cornerstone of successful aging. It helps prevent falls and the fear of falling and contributes to a general sense of well-being, of feeling at home in one’s own body.

I remember the incident that caused my father to quit driving when he was about 70 years old. While attempting to park the car in a small area just off the circular driveway — a maneuver that required several small adjustments — he went too far and ran over the neighbor’s hedge.

Dad was defensive and said the accelerator got stuck, which is unlikely. Because of his age and moderate memory difficulties, everyone assumed he had gotten confused and accelerated when he should have braked.

Years later, though, I had an “aha!” moment when I discovered proprioception in a motor learning class. Maneuvering a car over a short distance into a small space as Dad was doing requires a balance (!) of accelerating and braking. I’ll never know for sure, but I think he used the accelerator at the right time but applied too much pressure because of a proprioceptive error.

Scott McCredie explains in “Balance” that some loss in proprioceptive function is a natural part of aging that varies in different body parts. Hands retain most of this ability well into old age but feet do not fare as well. There, proprioception remains steady until about age 40 but decreases 20 percent by age 50 and as much as 75 percent by age 80.

Is all of this loss “natural,” though, or do we contribute to it with our actions? Many gerontologists agree that thick-soled shoes, like running shoes, exacerbate the problem. McCredie says “wearing this type of shoe is like trying to play the piano with gloves on; they desensitize the feet to proprioceptive input.”

Understanding proprioception brings us back to an over-reliance on vision. As we age, we may start giving in to proprioceptive loss — looking down as we navigate stairs, for example — without even knowing what it is.

Activities such as yoga and tai chi can improve balance, but we can also work on the sensory components of balance in our daily activities. Stand up and raise your foot to put on socks and shoes. Practice standing on one foot with your arms in different positions. Use a Bosu to challenge your stability. Force your balance system to “listen” to proprioceptive input by doing simpler balance exercises with eyes closed.

And get your feet out of their shoes and let them experience various surfaces inside and outside: different floor types (sisal mats can really give your feet something to think about) but also sand, rocks and grass.

Always think about safety first and consult a health care professional if you have a medical condition that affects balance. Practice eyes-closed movements only in a safe place, like your home, and consider using a spotter. But now that you know about the hidden sense of proprioception, you can consciously practice it to improve balance and sensitivity to large and small movements.