Why Our Balance Changes with Age
Like it or not, as we age our balance decreases. It is a natural result of many other changes that are occurring within the body. Keeping our balance is an essential component of our lives; whether it is being able to recover after slipping, or having to stand on our tippy-toes and reach for an item on that top shelf.
Our balance is regulated by three main systems: vestibular, somatosensory and visual; which all under-go changes as we age.
Vestibular Changes: Getting Dizzy
Did you know that balance is controlled by fluid in your ears? The vestibular system relays the movement of fluid from within the inner ear to the brain in order to coordinate our balance and proprioception in space. This vestibular fluid runs past little hairs that detect the movement and send sensory impulses to the brain.
If the movement of the fluid is accelerated in either direction, sensors detect it in the inner ear and send this signal to the brain to tell our body to compensate for this off-set in some other way. A simple example is when you spin in one direction really fast and then suddenly stop. We still feel as if we are in motion because the inertia from the fluid within the ears is still telling our brains we are in motion; hence why we feel off balance in these situations.
Structural changes to this system occur, making the integration of information that is being received more difficult to interpret. Certain medications also make us feel dizzy, further throwing off the input of the vestibular system to balance.
Reaction Time Slows Down
One natural change to our bodies that occurs with age is sarcopenia (age-related muscle loss). Did you know we lose 50% of our muscle from ages 50-90? With this comes a decrease in motor units. Motor units are responsible for delivering the message of movement from the brain to the muscle the brain wishes to use. With less brain to muscle control, it takes our bodies longer to react to perturbations, decreasing our balance.
We also lose fast-twitch muscle fibers more rapidly than slow-twitch muscle fibers. Fast-twitch muscle fibers are the first ones to be recruited in any sort of movement. They are needed when we make quick changes in direction. With a loss in these types of fibers, it takes our bodies longer than they once did to react.
Slow twitch motor neurons are forced to branch out and innervate the degenerated fast twitch motor unit muscles. The motor unit is therefore controlling more than it is used to. Having more muscle to manage takes longer for the tasks to be properly distributed, decreasing our reaction time.
Visual Changes: Not Being Able to See Our Surroundings
Another change that occurs with age is loss of vision and depth perception. Close your eyes and try to balance, you are removing one of the input systems that contribute to balance. When our visual abilities decrease, it runs along the same lines in that we are taking away from one of the external inputs, throwing off our balance. Peripheral vision is also affected with age, giving us a narrowing field of vision and not recognizing our surroundings causing us to trip more often. Diseases that affect our vision is more prominent as we age, having negative implications for our balance.
All three of these systems highly rely on the brain to register and react appropriately to what is throwing off our balance in our external surroundings. A study conducted by the University of Florence in 2008 has found that elderly people who have greater changes in their white brain matter (also known as leukoaraiosis) have more trouble with balance.
Researchers found those with severe changes to their white matter were two times as likely to score poor on the walking and balance tests, as well as had a two times greater history of falls than those who had mild changes in their white matter. Our brains ability to sense and detect the external inputs from all 3 systems is affected by the changes to the white matter.
It takes older adults longer to integrate sensory information from all 3 systems coming to the brain to control posture.
Cavanaugh, J.C. 2006. Adult development and aging. Thompson Wadsworth, USA. Pg. 46-47
Punitha, H. 2008. Loss of balance in old age attributed to brain. Senior Health News. Retrieved on Thursday December 9th, 2010.