Written by Michael E. Rogers, Ph.D., FACSM
Falls are one of the most serious health risks for older adults. They are not only the leading cause of injury-related deaths in this population, but they are also a significant cause of disability. In fact, falls cause ten percent of all emergency department visits and more than half of injury-related hospitalizations.
Approximately one in three older adults falls each year. As the number of older adults increases rapidly over the next decade, the annual cost for fall-related injuries is expected to skyrocket, reaching $44 billion by 2020. Although most falls don’t result in severe physical injuries, a fall or near-fall often produces a psychological fear of falling. This contributes to a self-imposed decrease in activity, followed by functional declines and a greater risk for falls.
Falls in older adults are often viewed as unpredictable and unavoidable accidents. However, identification of the factors linked to falls combined with appropriate interventions to correct these conditions can dramatically lessen the risk of a fall. In many cases, falls are caused by a loss of balance or the inability to maintain the body’s center of gravity (COG) over its base of support (BOS). There are two types of balance:
- Static balance, which is the ability to control postural sway during quiet standing; and
- Dynamic balance, which is the ability to react to changes in balance and to anticipate changes as the body moves. Dynamic balance includes maintaining balance while walking and stepping over or around objects.
The ability to balance depends in large part on sensory, muscular and motor systems. The three most influential sensory systems are the visual, vestibular and somatosensory systems. However, with advancing age, sensory function decreases, which negatively affects balance. Understanding these systems is essential to providing exercise programs that target balance for older adults.
The visual system is a major contributor to balance, providing information about the environment, the location of the person and the direction and speed of the person’s movement in the environment. Visual acuity, depth perception, peripheral field and sensitivity to low spatial frequencies (requiring more contrast to detect spatial differences) decrease with age. As a result, older adults tend to have a reduced ability to use visual cues to control balance.
The vestibular system, located in the ears, provides information about movement of the head, independent of visual cues. One component, the otoliths, detects head movement in relation to gravity, such as degree and direction of head tilt. The other component, the semicircular canals, are fluid-filled canals composed of three half circles positioned in three different planes. As the head moves, fluid in the canals triggers receptors and information is sent to the brain where it provides input about head orientation. At approximately age 40, vestibular neurons start to decrease in number and size, resulting in various impairments including dizziness.
The somatosensory system provides information about the body's position and contact from the skin through pressure, vibration and tactile sensors, as well as joint and muscle proprioceptors. Skin sensation via tactile, vibration and pressure sensors is important in all activities of daily living, especially those involving movement. Skin sensitivity is reduced with increasing age. Lack of input from tactile, pressure and vibration receptors makes it difficult to stand or walk and detect changes in heel-to-toe body weight shifts, which are important in maintaining balance.
In addition to the three sensory systems, muscle strength plays a role in balance and mobility. Muscles are particularly important in stability, since they work to keep the COG within the BOS.
A basic premise of exercise science is that in order to improve the function of a system through exercise, the exercise must stimulate that system (i.e., the principle of specificity). Many studies have shown that strength can be improved in older adults using different types of resistance training. However, resistance training alone has only a modest effect on improving balance, even though strength and balance are related. This is likely because the ability to maintain balance involves a several processes that require the successful integration of multiple components, including several sensory systems not typically affected by resistance training. Exercise programs that target the physiological systems in balance control, specifically the visual, vestibular, somatosensory and muscular systems, can improve balance and reduce the risk for falls.
Balance exercises involve maintaining standing and postural stability under a variety of static and dynamic conditions. Activities in a balance-training program can include standing with one foot in front of the other to alter the base of support, shifting the body weight in different directions and lifting the feet from the floor. Exercises can also be performed with the eyes closed, while moving the head and/or while standing on foam to target the visual, vestibular and somatosensory systems respectively. A variety of activities are used to increase strength using body weight or equipment such as cuff weights or elastic resistance bands. Exercises which simulate activities of daily living, such as reaching forward to put something on a shelf, can then incorporate resistance and dynamic balance to challenge balance further. However, when performing these exercises it is important to have a chair or other sturdy surface within reach in case it becomes necessary to steady one’s self.
The potential applications of balance training are tremendous. Training can be performed to reduce the risk of additional falls in chronic fallers or improve balance in aging adults who want to reduce the risk of their first fall.
Furthermore, balance exercises can be incorporated into rehabilitation programs for people with hip fracture, stroke and arthritis.
Reducing fall risk by improving balance in older adults will not only avoid increasing health care costs, but it also will give older adults a more active life. Further, providing effective interventions to target fall risk can make a major difference in quality of life for these individuals.
Photos used with permission from Hygenic Corporation.
View the full fall 2010 issue of the ACSM Fit Society® Page online.