This month I thought I would focus on the Sense of Balance.  It is never too early or late to be working on our sense of balance, but the sooner the better.

Sense of balance is the ability to maintain your body’s center of gravity. The effects of aging are the most common causes of balance problems.  Falling is such a common and potentially serious problem— 1 in 4 people over the age of 65 fall each year – You can decrease your risk and improve your general health and mobility by exercising your balance skills.

Sense of balance is the interaction between the nervous system and the following body parts:

•          Inner ear
•          Eyes
•          Skin receptors
•          Muscle and joint sensory receptors
•          Central Nervous system (brain and spinal cord)

Making sense of Balance

Effective balance training requires a working knowledge of the three sensory systems that control balance and how to safely challenge these systems.

By: Michael E. Rogers, PhD, and Phillip Page, PT, ATC

Balance training is often prescribed to rehabilitate a variety of ankle, knee, hip, and back injuries, and as a means to reduce fall risk in older adults.

Balance has been described as the ability of an individual to maintain his or her body's center of gravity over the base of support, whether that base of support is stationary (static balance) or moving (dynamic balance).  While maintaining balance, a person responds to both external forces that can destabilize the body's center of gravity and internal forces that result from the body's movements. A wide variety of external and internal forces challenge the body by altering its center of gravity. To maintain balance, a person must sense these forces and execute muscle responses that offset them, a skill that is achieved by the coordinated efforts of sensory and motor systems. Three sensory systems provide input regarding the body's position and movement through the surrounding environment: the visual, vestibular, and somatosensory systems.

Visual system. The visual system is a major contributor to balance, providing information about the environment, the body's location within that environment, and the direction and speed of movement within the environment. The visual system provides information through the clarity with which it sees and via information that is collected as a person moves through space. When visual information is reduced (e.g., by closing the eyes) in younger adults, postural sway increases. Conversely, stance is steadied when the eyes are open and fixed on a point of reference. As they age, people tend to lose their ability to use visual cues to control static balance. This may be a result of declines in the visual field, contrast sensitivity, and depth perception that typically occur during the aging process.

Vestibular system. Located in the inner ear and consisting of otoliths and semicircular canals, the vestibular system provides information about head movement independent of visual cues. The otoliths are responsible for detecting movement with respect to gravity, such as degree and direction of head tilt. The semicircular canals comprise three fluid-filled passages positioned in the frontal, sagittal, and horizontal planes. As the head moves, movement of fluid in the canals triggers receptors and information regarding head orientation is sent to the brain. After the age of 40, the number and size of vestibular neurons often decreases, and it is estimated that 40% of an individual's vestibular sensory cells no longer function by the age of 70.

Somatosensory system. The somatosensory system provides information about the body's position via skin and muscle receptors. Skin receptors relay information about temperature, pressure, vibration, and tactile sensation. Failure of these receptors is demonstrated when, for instance, a foot "falls asleep," when a patient has diabetic peripheral neuropathy. This loss of sensory input from receptors makes it very difficult to sense forces acting on the body and balance is difficult to maintain.

Additional information about muscle displacement is provided by muscle receptors. When a muscle is lengthened during movement, stretch receptors in the muscle send signals to the central nervous system until the muscle is contracted and the desired length and tension of the muscle is regained. The skin and muscle receptors work together to detect the effects of the surrounding environment and to provide feedback regarding muscle contractions that may be required to maintain balance as the individual interacts with that environment. This system is particularly important because of the information it provides regarding weight shifts from one foot to another, both while standing in place and while ambulating.

Sensory and motor integration. The afferent information sent to the central nervous system by these three sensory systems is processed at the spinal cord (reflex activations), the lower- and midbrain (automatic activations), and the brain cortex (voluntary movements). Precise transmission of sensory information and rapid and accurate information processing at each of these levels are essential for maintaining balance. Once information is transmitted to and processed by one of these systems, a response is executed by the muscular, or motor, system to maintain balance. If any of these sensorimotor systems is impaired, the body's ability to sustain postural balance is diminished. Therefore, it is essential to address both sensory and motor components during balance training and integrate these systems to elicit appropriate responses to feedback.

Training

Based on the principle of exercise specificity and the multidimensional aspects of balance, training programs should be customized to target the systems involved in balance control, particularly the muscular, visual, vestibular, and somatosensory systems.  Like all other types of exercise - balance training should progressively overload the physiological systems being trained to encourage adaptation. Balance training exercises should progressively become more challenging.

Source: BioMechanics

Studies show that people tend to loose about .5% of their balance every year from about the age of 20. Therefore by the age of 40 you have lost about 10% of your balance capability. Decreased luscle strength, weakening bones along with decreased mobility at the knees and ankles also increase the chances of losing balance.  Good news is that balance is a skill and you can regain balance by exercise.  We also lose muscle mass as we age

Check out my "Exercises for improved balance" in order to help regain that sense of balance.

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