Chapter 8: Exercise for Impaired Balance

Loss of balance and falling are problems that affect individuals with a wide range of diagnoses. Physical therapists commonly evaluate balance and use balance training/exercises as either primary or secondary interventions for patients undergoing many types of rehabilitation programs. Because of the importance of balance assessment and treatment in clinical practice, The Guide to Physical Therapist Practice⁵ has designated an entire preferred practice pattern (pattern 5A) to primary prevention/risk reduction for loss of balance and falling. The purpose of this chapter is to present an overview of key background terms and concepts related to balance, how balance control is normally achieved in humans for a variety of conditions, possible causes of balance impairments, and evidence-based assessments and interventions for enhancing all aspects of an individual's balance control.

Balance: Key Terms and Definitions

Balance, or postural stability, is a generic term used to describe the dynamic process by which the body's position is maintained in equilibrium. Equilibrium means that the body is either at rest (static equilibrium) or in steady-state motion (dynamic equilibrium). Balance is greatest when the body's center of mass (COM) or center of gravity (COG) is maintained over its base of support (BOS).

Center of mass. The COM is a point that corresponds to the center of the total body mass and is the point at which the body is in perfect equilibrium. It is determined by finding the weighted average of the COM of each body segment.¹³⁵

Center of gravity. The COG refers to the vertical projection of the center of mass to the ground. In the anatomical position, the COG of most adult humans is located slightly anterior to the second sacral vertebra¹⁴ or approximately 55% of a person's height.⁵⁵

Momentum. Momentum is the product of mass times velocity. Linear momentum relates to the velocity of the body along a straight path, for example, in the sagittal or transverse planes. Angular momentum relates to the rotational velocity of the body.

Base of support. The BOS is defined as the perimeter of the contact area between the body and its support surface; foot placement alters the BOS and changes a person's postural stability.¹⁰⁶ A wide stance, such as is seen with many elderly individuals, increases stability, whereas a narrow BOS, such as tandem stance or walking, reduces it. So long as a person maintains the COG within the limits of the BOS, referred to as the limits of stability, he or she does not fall.

Limits of stability. "Limits of stability" refers to the sway boundaries in which an individual can maintain equilibrium without changing his or her BOS (Fig. 8.1).¹⁰⁶ These boundaries are constantly changing depending on the task, the individual's biomechanics, and aspects of the environment.¹³⁷ For example, the limits of stability for a person during quiet stance is the area encompassed by the outer edges of the feet in contact with the ground. Any deviations in the body's COM position relative to this boundary are corrected intermittently, producing a random swaying motion. For normal adults, the antero-posterior sway limit is approximately 12° from the most posterior to most anterior position.¹⁰⁷ Lateral stability varies with foot spacing and height; adults standing with 4 inches between the feet can sway approximately 16° from side to side.¹⁰⁵ However, a person sitting without trunk support has much greater limits of stability than when standing, because the height of the COM above the BOS is less and the BOS is much larger (i.e., perimeter of the buttocks in contact with a surface).

Ground reaction force and center of pressure. In accordance with Newton's law of reaction, the contact between our bodies and the ground due to gravity (action forces) is always accompanied by a reaction from it, the so-called ground reaction force.

The center of pressure (COP) is the location of the vertical projection of the ground reaction force.¹⁶² It is equal and opposite to the weighted average of all the downward forces acting on the area in contact with the ground. If one foot is on the ground, the net COP lies within that foot. When both feet are on the ground, the net COP lies somewhere between the two feet, depending on how much weight is taken by each foot. When both feet are in contact, the COP under each foot can be measured separately. To maintain stability, a person produces muscular forces to continually control the position of the COG, which in turn changes the location of the COP. Thus, the COP is a reflection of the body's neuromuscular responses to imbalances of the COG.¹⁶³ A force plate is traditionally used to measure ground reaction forces (in Newtons [N]) and COP movements (in meters [m]).

Balance Control

Balance is a complex motor control task involving the detection and integration of sensory information to assess the position and motion of the body in space and the execution of appropriate musculoskeletal responses to control body position within the context of the environment and task. Thus, balance control requires the interaction of the nervous and musculoskeletal systems and contextual effects (Fig. 8.2).

• The nervous system provides the (1) sensory processing for perception of body orientation in space provided mainly by the visual, vestibular, and somatosensory systems; (2) sensorimotor integration essential for linking sensation to motor responses and for adaptive and anticipatory (i.e., centrally programmed postural adjustments that precede voluntary movements) aspects of postural control; and (3) motor strategies for planning, programming, and executing balance responses.⁶⁰

• Musculoskeletal contributions include postural alignment, musculoskeletal flexibility such as joint range of motion (ROM), joint integrity, muscle performance (i.e., muscle strength, power, and endurance), and sensation (touch, pressure, vibration, proprioception, and kinesthesia).

• Contextual effects that interact with the two systems are the environment whether it is closed (predictable with no distractions) or open (unpredictable and with distractions), the support surface (i.e., firm versus slippery, stable versus unstable, type of shoes), the amount of lighting, effects of gravity and inertial forces on the body, and task characteristics (i.e., well-learned versus new, predictable versus unpredictable, single versus multiple tasks).

Even if all elements of the neurological and musculoskeletal systems are operating effectively, a person may fall if contextual effects force the balance control demands to be so high that the person's internal mechanisms are overwhelmed.

Sensory Systems and Balance Control

Perception of one's body position and movement in space require a combination of information from peripheral receptors in multiple sensory systems, including the visual, somatosensory (proprioceptive, joint, and cutaneous receptors), and vestibular systems.

Visual System

The visual system provides information regarding (1) the position of the head relative to the environment; (2) the orientation of the head to maintain level gaze; and (3) the direction and speed of head movements, because as your head moves, surrounding objects move in the opposite direction. Visual stimuli can be used to improve a person's stability when proprioceptive or vestibular inputs are unreliable by fixating the gaze on an object. Conversely, visual inputs sometimes provide inaccurate information for balance control, such as when a person is stationary and a large object, such as a nearby bus, starts moving, causing the person to have an illusion of movement.

Somatosensory System

The somatosensory system provides information about the position and motion of the body and body parts relative to each other and the support surface. Muscle proprioceptors, including muscle spindles and Golgi tendon organs (sensitive to muscle length and tension), joint receptors (sensitive to joint position, movement, and stress), and skin mechanoreceptors (sensitive to vibration, light touch, deep pressure, skin stretch), are the dominant sensory inputs for maintaining balance when the support surface is firm, flat, and fixed. However, when standing on a surface that is moving (e.g., on a boat) or on a surface that is not horizontal (e.g., on a ramp), inputs about body position with respect to the surface are not appropriate for maintaining balance; therefore, a person must rely on other sensory inputs for stability in these conditions.¹³⁷

Information from joint receptors does not contribute greatly to conscious joint position sense. It has been demonstrated that local anesthetization of joint tissues and total joint replacement does not impair joint position awareness.^50,51 Muscle spindle receptors appear to be mostly responsible for providing joint position sense, whereas the primary role of joint receptors is to assist the gamma motor system in regulating muscle tone and stiffness to provide anticipatory postural adjustments and to counteract unexpected postural disturbances.¹¹³

Vestibular System

The vestibular system provides information about the position and movement of the head with respect to gravity and inertial forces. Receptors in the semicircular canals (SCCs) detect angular acceleration of the head, whereas the receptors in the otoliths (utricle and saccule) detect linear acceleration and head position with respect to gravity. The SCCs are particularly sensitive to fast head movements, such as those made during walking or during episodes of imbalance (slips, trips, stumbles), whereas the otoliths respond to slow head movements, such as during postural sway.^59,137

By itself, the vestibular system can give no information about the position of the body. For example, it cannot distinguish a simple head nod (head movement on a stable trunk) from a forward bend (head movement in conjunction with a moving trunk).⁵⁹ Consequently, additional information, particularly from mechanoreceptors in the neck, must be provided for the central nervous system (CNS) to have a true picture of the orientation of the head relative to the body.¹¹³

The vestibular system uses motor pathways originating from the vestibular nuclei for postural control and coordination of eye and head movements. The vestibulospinal reflex brings about postural changes to compensate for tilts and movements of the body through vestibulospinal tract projections to antigravity muscles at all levels of the spinal cord. The vestibulo-ocular reflex stabilizes vision during head and body movements through projections from the vestibular nuclei to the nuclei that innervate extraocular muscles.

Sensory Organization for Balance Control

Vestibular, visual, and somatosensory inputs are normally combined seamlessly to produce our sense of orientation and movement.¹¹³ Incoming sensory information is integrated and processed in the cerebellum, basal ganglia, and supplementary motor area.¹⁶¹ Somatosensory information has the fastest processing time for rapid responses, followed by visual and vestibular inputs.¹⁶¹ When sensory inputs from one system are inaccurate owing to environmental conditions or injuries that decrease the information-processing rate, the CNS must suppress the inaccurate input and select and combine the appropriate sensory inputs from the other two systems. This adaptive process is called sensory organization. Most individuals can compensate well if one of the three systems is impaired; therefore, this concept is the basis for many treatment programs.

Types of Balance Control

Functional tasks require different types of balance control, including (1) static balance control to maintain a stable anti-gravity position while at rest, such as when standing and sitting; (2) dynamic balance control to stabilize the body when the support surface is moving or when the body is moving on a stable surface, such as sit-to-stand transfers or walking; and (3) automatic postural reactions to maintain balance in response to unexpected external perturbations, such as standing on a bus that suddenly accelerates forward.

• Feedforward (open loop motor control) is utilized for movements that occur too fast to rely on sensory feedback (e.g., reactive responses) or for anticipatory aspects of postural control.

• Anticipatory control involves activation of postural muscles in advance of performing skilled movements, such as activation of posterior leg and back extensor muscles prior to a person pulling on a handle when standing³⁰ or planning how to navigate to avoid obstacles in the environment.

• Closed loop control is utilized for precision movements that require sensory feedback (e.g., maintaining balance while sitting on a ball or standing on a balance beam).

Motor Strategies for Balance Control

To maintain balance, the body must continually adjust its position in space to keep the COM of an individual over the BOS or to bring the COM back to that position after a perturbation. Horak and Nashner⁶¹ described three primary movement strategies used by healthy adults to recover balance in response to sudden perturbations of the supporting surface (i.e., brief anterior or posterior platform displacements) called ankle, hip, and stepping strategies (Fig. 8.3). Factors that determine which strategy most effectively addresses a balance disturbance are identified in Box 8.1. Results of research examining the patterns of muscle activity underlying these movement strategies suggest that preprogrammed muscle synergies comprise the fundamental movement unit used to restore balance.^61,103,108 A synergy is a functional coupling of groups of muscles, so they must act together as a unit; this organization greatly simplifies the control demands of the CNS.

The CNS uses three movement systems to regain balance after the body is perturbed: reflex, automatic, and voluntary systems. Table 8.1 summarizes the key characteristics of reflexes, automatic postural responses, and voluntary movements.¹⁰⁵

• "Stretch" reflexes mediated by the spinal cord comprise the first response to external perturbations. They have the shortest latencies (<70 ms), are independent of task demands, and produce stereotyped muscle contractions in response to sensory inputs.

• Voluntary responses have the longest latencies (>150 ms), are dependent on task parameters, and produce highly variable motor outputs (e.g., reach for a nearby stable support surface or walk away from a destabilizing condition).

• Automatic postural reactions have intermediate latencies (80 to 120 ms) and are the first responses that effectively prevent falls. They produce quick, relatively invariant movements among individuals (similar to reflexes), but they require coordination of responses among body regions and are modifiable depending on the demands of the task (similar to voluntary responses).

The reflex, automatic, and voluntary movement systems interact to ensure that the response matches the postural challenge.

Ankle Strategy (Anteroposterior Plane)

In quiet stance and during small perturbations (i.e., slow-speed perturbations usually occurring on a large, firm surface), movements at the ankle act to restore a person's COM to a stable position. For small external perturbations that cause loss of balance in a forward direction (i.e., platform displacements in a backward direction), muscle activation usually proceeds in a distal to proximal sequence: gastrocnemius activity beginning about 90 to 100 ms after perturbation onset, followed by the hamstrings 20 to 30 ms later, and finally paraspinal muscle activation.^104,105 In response to backward instability, muscle activity begins in the anterior tibialis, followed by the quadriceps and abdominal muscles.

Weight-Shift Strategy (Lateral Plane)

The movement strategy utilized to control mediolateral perturbations involves shifting the body weight laterally from one leg to the other. The hips are the key control points of the weight-shift strategy. They move the COM in a lateral plane primarily through activation of hip abductor and adductor muscles, with some contribution from ankle invertors and evertors.¹⁰⁵

Suspension Strategy

The suspension strategy is observed during balance tasks when a person quickly lowers his or her body COM by flexing the knees, causing associated flexion of the ankles and hips.¹⁰⁶ The suspension strategy can be combined with the ankle or the weight-shift strategy to enhance the effectiveness of a balance movement.¹⁰⁶

Hip Strategy

For rapid and/or large external perturbations or for movements executed with the COG near the limits of stability, a hip strategy is employed.¹⁰⁶ The hip strategy uses rapid hip flexion or extension to move the COM within the BOS.¹⁶² As the trunk rotates rapidly in one direction, horizontal (shear) forces are generated against the support surface in the opposite direction moving the COM in the opposite direction as the trunk.¹⁰⁶ The muscle activity associated with the hip strategy has been studied by having a person stand crosswise on a narrow balance beam while the support surface suddenly moves backward (i.e., person sways forward) or forward (i.e., person sways backward).⁶¹ In response to a forward body sway, muscles are typically activated in a proximal to distal sequence: Abdominals beginning about 90 to 100 ms after perturbation onset followed by activation of the quadriceps. Backward body sway results in activation first of the paraspinals followed by the hamstrings. A person cannot use the hip strategy to restore balance while walking on slippery surfaces, because the large horizontal forces generated cause the feet to slip.

Stepping Strategy

If a large force displaces the COM beyond the limits of stability, a forward or backward step is used to enlarge the BOS and regain balance control. The uncoordinated step that follows a stumble on uneven ground is an example of a stepping strategy.

Combined Strategies

Research has shown that movement response patterns to postural perturbations are more complex and variable than originally described by Nashner.⁷⁵ Most healthy individuals use combinations of strategies to maintain balance depending on the control demands. Balance control requirements vary depending on the task and the environment. For example, standing on a bus that is moving has higher control demands than standing on a fixed surface. Therefore, it is important during treatment of balance disorders to vary the task and environment, so the person develops movement strategies for different situations.

Balance Control Under Varying Conditions

Balance During Stance

In quiet stance, the body sways like an inverted pendulum about the ankle joint.¹⁶² The balance goal is to keep the body's COM safely within the BOS. To accomplish this goal, an ankle strategy is utilized in which ankle muscles (i.e., ankle plantarflexors/ dorsiflexors, invertors/evertors) are automatically and selectively activated to counteract body sway in different directions. Other muscles that are tonically active during quiet stance to maintain an erect posture are the gluteus medius and tensor fasciae latae, the iliopsoas to prevent hyperextension of the hip, and the thoracic paraspinals (with some intermittent abdominal activation).⁹ Body alignment contributes to stability in quiet stance. Standing with the body in optimal body alignment allows the body to maintain balance with the least amount of muscle energy expenditure.¹³⁷

Balance with Perturbed Standing

Perturbations to balance in standing can be either internal (i.e., voluntary movement of the body) or external (i.e., forces applied to the body). Both types of perturbations involve activation of muscle synergies, but the response timing is proactive (i.e., anticipatory) for internally generated perturbations and reactive for externally generated perturbations.¹⁶²

Moving platform experiments have provided much information about the motor strategies (i.e., ankle, hip, and stepping strategies) and associated muscle activation patterns that result when a person is standing on a surface that unexpectedly translates or tilts.^{76,102,104,106} With repetition of a platform perturbation, learning adaptation occurs that is characterized by a significant reduction in the reactive response.^91,102 For example, Nashner¹⁰² found that upward rotation of a platform initially elicited reflex contractions of the gastrocnemius muscles of subjects, giving them the false impression that their bodies were falling forward; with repeated tilts, the gastrocnemius response diminished, and by the fourth repetition, it was completely absent. Thus, prior experience and feedforward anticipatory control have an important influence on balance responses.

Balance During Whole-Body Lifting

One of the most common ways that balance is challenged during everyday life is when lifting boxes or other large objects that are resting on the floor or at a level that is low relative to the person's COM (Fig. 8.4). Loss of balance during lifting may result in a fall, slip, or back injury.^6,121,132

COM shift. During lifting, the movement of the body toward the load disturbs the position of the COM. When a load is lifted in front of the body, the COM is shifted forward during flexion of the trunk and legs, which is an internal disturbance to balance. The COM is further displaced forward when the load is added to the hands, creating an external disturbance to balance. In this case, anticipatory postural adjustments are needed to match whole-body backward momentum (horizontal linear and angular) to the displacement of the body and magnitude of the expected load.^29,53,54 The CNS estimates the amount of momentum necessary for lifting the load based on previous experience with the load or other objects of similar physical properties (e.g., size, weight, and density).⁵⁴ The generation of backward horizontal linear momentum serves to keep the COM of the body within the base of support. The generation of angular momentum is essential for movement of the person with the load toward the upright posture.

Anticipated weight and momentum. The amount of whole-body momentum and the lifting force generated are scaled to the anticipated weight of the load.⁵⁴ When a heavy load is expected, sufficient levels of backward horizontal and angular momentum are needed to counteract the additional load, which tends to pull and rotate the body COM forward. Subtle differences in lifting posture, which reflect the underlying differences in momentum, occur when subjects lift a light load versus a heavy load (Fig. 8.5). Subjects tend to flex their hips and knees more and shift their weight back when lifting a heavy load (dark circles) than when lifting a light load (light circles).

Loss of balance. Loss of balance during lifting can occur when subjects overestimate or underestimate the weight of the load.⁵³ When the load weight is overestimated, too much momentum is generated and the body tends to topple backward. Most subjects compensate for this loss of balance by taking a step backward. When the load weight is underestimated, too little momentum is generated and the body tends to topple forward, resulting in the load quickly coming back to the ground.

Lifting style. The lifting style does appear to affect the challenges to balance. Keeping the knees more extended during lifting (Fig. 8.6) reduces the risk of balance loss, especially when the quadriceps are weak. Research comparing lifting styles has found that loss of balance was more common when subjects used a style of lifting in which the knees were more flexed compared to when the knees were straighter.^26,28,53,147

Lifting instructions. Clinicians frequently instruct patients to use the leg lifting style, with the knees bent and the trunk erect, when lifting loads (Fig. 8.7).^97,140 This recommendation is based on the assumption that leg lifting imposes lower compression loads on the spine than other styles of lifting, such as the stoop lift, with the knees straight and the trunk flexed.⁸² This assumption is likely true when the load to be lifted can be placed between the feet (Figs. 8.7 and 8.8). However, van Dieen and colleagues¹⁵³ found little evidence in the biomechanical literature to support that leg lifting generally results in lower loads on the spine than back lifting. Recent research, using sophisticated biomechanical models, indicates that leg lifting results in higher compression forces on the spine compared to back lifting when the load is not positioned between the legs.^23,34,77,119 Although researchers have consistently found that bending moments and fascial strain are substantially greater with the back lift compared to the squat lift,^34,35 the magnitude of the bending moments on the spine appear to be well below the threshold for injury.^1,34,152

Lifting styles. Based on the current literature, it appears that if the objective of training for lifting is to reduce the load on the lumbar spine, other factors that have a more substantial effect on reducing the load on the lumbar spine should be emphasized over the selection of a lifting style, especially when placing the load between the legs is not feasible.

If maintaining balance is a concern—especially in the elderly—lifting styles in which the knees are more extended, such as with the semi-squat and stoop lift, are probably safer. In younger individuals with strong quadriceps, the straddle lift with one leg in front of the other to widen the base of support would reduce the risk of balance loss.

Balance in Unperturbed Human Gait

During walking, the COM is always outside the BOS except during the short double support period.¹⁶² Therefore, the balance goal is to move the body outside the BOS by letting the body fall forward and yet prevent a fall. To accomplish this goal, a person must be able to maintain balance and posture of the upper body (i.e., head, arms, trunk) and vertical alignment of the body against gravity. Trunk and hip muscles (flexors/ extensors in the sagittal plane; abductors/adductors in the frontal plane) keep the upper body balanced, and extensor muscles of the lower extremities prevent vertical collapse.^162,163 The ankle muscles control anterior/posterior or medial/lateral acceleration of the body's COG but are not able to prevent falls.¹⁶² Fine motor control of the foot during the swing phase involving anticipatory activation of the ankle dorsiflexors ensures minimum toe clearance (0.55 cm) to prevent trips.¹¹⁷

Impaired balance can be caused by injury or disease to any structures involved in the three stages of information processing—sensory input, sensorimotor integration, and motor output generation.

Sensory Input Impairments

Proprioceptive deficits have been implicated as contributing to balance impairments following lower extremity and trunk injuries or pathologies. Decreased joint position sense has been reported in individuals with recurrent ankle sprains,^13,43,45,49 knee ligamentous injuries,^8,116,128 degenerative joint disease,⁸ and low back pain.^16,47,81 These same conditions have been associated with increased postural sway compared to that of controls.^{3,19,31,43,45,81,98,159} It is unclear whether decreased joint position sense is due to changes in joint receptors or in muscle receptors.

Somatosensory, visual, or vestibular deficits may impair balance and mobility.

• Reduced somatosensation in the lower extremities caused by peripheral polyneuropathies in the aged and in individuals with diabetes are associated with balance deficits^{123,124,138,151} and an increased risk for falls.^68,124 These individuals tend to rely more heavily on a hip strategy to maintain balance than do those without somatosensory deficits.⁶²

• Visual loss or specific deficits in acuity, contrast sensitivity, peripheral field vision, and depth perception caused by disease, trauma, or aging can impair balance and lead to falls.^25,71

• Individuals with damage to the vestibular system due to viral infections, traumatic brain injury (TBI), or aging may experience vertigo (a feeling of spinning) and postural instability. Black and colleagues¹¹ found that patients with severe bilateral loss of vestibular function are unable to use hip strategies even when standing crosswise on a narrow beam, although ankle strategies are unaffected.

Sensorimotor Integration Impairments

Damage to the basal ganglia, cerebellum, or supplementary motor area impair processing of incoming sensory information, resulting in difficulty adapting sensory information in response to environmental changes and in disruption of anticipatory and reactive postural adjustments.^63,105,137 When stance is perturbed by platform translations, patients with Parkinson's disease tend to have a smaller than normal amplitude of movement due to co-activation of muscles on both sides of the body, whereas patients with cerebellar lesions typically demonstrate larger response amplitudes.¹³⁷

Sensory organization problems that manifest as over-reliance on one particular sense for balance control or a more generalized inability to select an appropriate sense for balance control when one or more senses give inaccurate information have been demonstrated in patients with a wide variety of neurological conditions.¹³⁷ Individuals who rely heavily on visual inputs (visually dependent) or somatosensory inputs (surface dependent) become unstable or fall under conditions in which the preferred sense is either absent or inaccurate, whereas those with generalized adaptation problems are unstable in any condition in which a sensory input is not accurate.

Biomechanical and Motor Output Impairments

Deficits in the motor components of balance control can be caused by musculoskeletal (i.e., poor posture, joint ROM limitations, decreased muscle performance) and/or neuromuscular system (i.e., impaired motor coordination, pain) impairments. Postural malalignment, such as the typical thoracic kyphosis of the elderly, that shifts the COM away from the center of the BOS increases a person's chance of exceeding his or her limits of stability.¹⁰⁵ Because each segment within the legs exerts forces on its adjunct segments, impaired ROM or muscle strength at one joint can alter posture and balance movements throughout the entire limb. For example, restriction of ankle motion by contractures or wearing ankle-foot orthoses and/or ankle dorsiflexor weakness eliminates the use of an ankle strategy, resulting in increased use of hip and trunk muscles for balance control.^18,130

In individuals with neurological conditions (e.g., stroke, TBI, Parkinson's disease), failure to generate adequate muscle forces due to abnormal tone or impaired coordination of motor strategies may limit the person's ability to recruit muscles required for balance.¹³⁷

Pain can alter movements, reduce a person's normal stability limits, and, if persistent, produce secondary strength and mobility impairments.

Deficits with Aging

Falls are common and are a major cause of morbidity, mortality, reduced functioning, and premature nursing home admissions in persons over age 65.^{25,36,109,127,129} The most common risk factors associated with falls in the elderly are listed in Box 8.2. Most falls by the elderly are likely due to complex interactions between multiple risk factors. Clinicians are encouraged to follow published guidelines for the prevention of falls by older persons when prescribing fall prevention interventions.⁴

Declines in all sensory systems (somatosensory, vision, vestibular) and all three stages of information processing (i.e., sensory processing, sensorimotor integration, motor output) are found with aging.^83,137 In comparison to young adults, older adults have more difficulty maintaining balance when sensory inputs from more than one system are greatly reduced, particularly when they must rely solely on vestibular inputs for balance control.^124,165 Studies of response patterns to platform perturbations in older adults have demonstrated the following motor strategy changes compared to those of young adults.

• Slower-onset latencies^139,165

• More frequent use of a hip strategy for balance control⁶⁴

• Limitations in the ability to maintain balance when challenged with perturbations of increasing magnitude and velocity⁸⁴

Impaired anticipatory postural adjustments prior to making voluntary movements have been demonstrated in older individuals and may explain the high incidence of falls during activities such as walking, lifting, and carrying objects.^42,70 Valid and reliable outcome measures for assessing fall risk in the elderly are listed in Table 8.2.

Elderly individuals who have experienced one or more falls may develop fear of falling, which leads to a loss of confidence in a person's ability to perform routine tasks, restricted activity, social isolation, functional decline, depression, and decreased quality of life.^25,79 The fear of falling arises more often from a person's fear of institutionalization than a fear of injury.⁶⁷ Individuals with fear of falling demonstrate perceived stability limits that are reduced from their actual stability limits and gait changes, including decreased stride length, reduced speed, increased stride width, and increased double-support time.^24,90 It is important that clinicians screen patients for fear of falling with instruments, such as the Activities-Specific Balance Confidence (ABC) Scale¹²⁰ or the Fall Efficacy Scale,¹⁴⁵ so evidence-based interventions that reduce fear of falling and promote physical, social, and functional activity are implemented.^15,141,156

Deficits from Medications

There is an increased risk of falling among older individuals who take four or more medications and among those taking certain medications (i.e., hypnotics, sedatives, tricyclic antidepressants, tranquilizers, antihypertensive drugs) due to dizziness or other side effects.^4,25 Individuals who have fallen should have their medications reviewed and altered or stopped as appropriate to prevent future falls.

Examination and Evaluation of Impaired Balance

The key elements of a comprehensive evaluation of individuals with balance problems include the following.

• A thorough history of falls (whether onset of falls is sudden versus gradual; the frequency and direction of falls; the environmental conditions, activities, and presence of dizziness, vertigo, or lightheadedness at time of the fall; current and past medications; presence of fear of falling)

• Assessments to identify sensory input (proprioceptive, visual, vestibular), sensory processing (sensorimotor integration, anticipatory and reactive balance control), and biomechanical and motor (postural alignment, muscle strength and endurance, joint ROM and flexibility, motor coordination, pain) impairments contributing to balance deficits

• Tests and observations to determine the impact of balance control system deficits on functional performance

• Environmental assessments to determine fall risk hazards in a person's home.²⁵

Commonly used tests and measures for each of the three categories of balance assessment described in the Guide to Physical Therapist Practice⁵ are presented in Table 8.3. Clinicians should carefully select a variety of tests and measures that assess all of the various types of balance control.

Static Balance Tests

Static balance can be assessed by observing the patient's ability to maintain different postures.

• The Romberg Test¹¹⁰ tests the patient's ability to stand with the feet parallel and together with the eyes open and then closed for 30 seconds..

• The sharpened Romberg, also known as the tandem Romberg,¹¹⁰ requires the patient to stand with the feet in a heel-to-toe position with arms folded across the chest and eyes closed for one minute.

• The Single-Leg Balance Stance Test¹⁵⁴ (SLB) asks the patient to stand on one leg without shoes with arms placed across the chest without letting the legs touch each other. Five 30-second trials are performed for each leg, with a maximum possible score of 150 seconds per leg. The SLB is reliable and has been found to predict injurious falls in community-dwelling elderly¹⁵⁴ and ankle sprains in athletes.¹⁴⁸

• The Stork Stand Test⁷⁴ is performed by having the patient stand on both feet with hands on the hips, then lift one leg and place the toes of that foot against the knee of the other leg. On command from the tester, the patient then raises the heel to stand on the toes and tries to balance for as long as possible without letting either the heel touch the ground or the other foot move away from the knee. Normal adults should be able to balance for 20 to 30 seconds on each leg.

Dynamic Balance Tests

Dynamic balance control can be assessed by observations of how well the patient is able to stand or sit on unstable surfaces (e.g., foam or Swiss ball), transition from one position to another (e.g., supine-to-sit or sit-to-stand transfers), and perform activities such as walking, jumping, hopping, and skipping.

• The Five-times-sit-to-stand test (5 × STS) can be used to evaluate balance control when moving between sitting and standing.³² The person is seated in a chair with the arms across the chest and then stands up and sits back down as quickly as possible five times consecutively while being timed. A score of >15 seconds on the 5 × STS was found to predict recurrent falls (sensitivity 55%, specificity 65%) in 2,735 community-dwelling elderly individuals.¹⁷

Anticipatory Postural Control Tests

Anticipatory postural control is evaluated by having the patient perform voluntary movements that require the development of a postural set to counteract a predicted postural disturbance. The patient's ability to catch balls, open doors, lift objects of different weights, and reach without losing balance is indicative of adequate anticipatory control.

• The Functional Reach Test³⁷ and the Multi-Directional Reach Test¹¹¹ require the patient to reach in different directions as far as possible without changing the BOS. Normative data are available, and the tests are reliable and valid.¹¹¹

• The Star Excursion Balance Test is a test of lower extremity reach that challenges an individual's limits of stability.¹¹⁴ The patient is instructed to reach as far as possible with one leg in each of eight prescribed directions while maintaining balance on the contralateral leg. The test is reliable^56,78 and can detect deficits in individuals with chronic ankle instability.^57,114

Reactive Postural Control Tests

Automatic postural responses or reactive control can be assessed by the patient's response to external perturbations.

• Pushes (small or large, slow or rapid, anticipated and unanticipated) applied in different directions to the sternum, posterior trunk, or pelvis are used widely, but they are not quantifiable or reliable. The clinician subjectively rates the responses as normal, good, fair, poor, or unable.

• The Pull Test,¹⁰¹ Push and Release Test,⁷² and Postural Stress Test¹⁶⁴ are more objective and reliable measures of reactive postural control.

Sensory Organization Tests

The Clinical Test of Sensory Integration on Balance Test (CTSIB), also called the "Foam and Dome" Test,¹³⁵ measures the patient's ability to balance under six different sensory conditions.

1. Standing on a firm surface with the eyes open (visual, somatosensory, and vestibular information accurate);

2. Standing on a firm surface with the eyes closed (somatosensory and vestibular information accurate);

3. Standing on a firm surface wearing a dome made from a modified Japanese lantern (somatosensory and vestibular information accurate, visual information inaccurate);

4. Standing on a foam cushion with the eyes open (visual and vestibular information accurate, somatosensory inaccurate);

5. Standing on foam with the eyes closed (vestibular information accurate, somatosensory information inaccurate); and

6. Standing on foam wearing the dome (vestibular information accurate, somatosensory and visual information inaccurate).

The patient stands with feet parallel and arms at sides or hands on hips. A minimum of three 30-second trials of each condition are performed.

• Individuals who rely heavily on visual inputs for balance (i.e., visual dependent) will become unstable or fall in conditions 2, 3, 5, and 6.

• Those who rely heavily on somatosensory inputs (i.e., surface dependent) show deficits with conditions 4, 5, and 6.

• With generalized adaptation problems, individuals are unstable in conditions 3, 4, 5, and 6.

• Individuals with vestibular loss are very unstable in conditions 5 and 6.

NOTE: A computerized version of the CTSIB using a moveable force plate and visual surround is called the Sensory Organization Test (SOT).¹⁰⁵

Functional Tests

Functional tests are used to determine activity limitations and participation restrictions and to identify tasks that a patient needs to practice. Three mobility scales (i.e., Tinetti Performance-Oriented Mobility Assessment [POMA],¹⁴⁴ Timed Up and Go Test [TUG],¹¹⁸ Berg Balance Scale,¹⁰ Four Square Step Test [4SST³³]), and two gait scales (i.e., Dynamic Gait Index¹³⁷ and Functional Gait Assessment¹⁶⁷) can be easily used to assess balance performance during functional activities. Most of these tests were designed to assess fall risk in the elderly, with the exception of the Functional Gait Assessment, which was developed specifically for use with patients with vestibular disorders. The Community Balance and Mobility Scale⁶⁵ and the High Level Mobility Assessment Tool (HiMAT)¹⁶⁰ can be used to evaluate balance and mobility in people who are ambulatory and functioning at a high level, yet have some balance deficits. The 25-item Dizziness Handicap Scale is a questionnaire that can evaluate the self-perceived impact of dizziness and unsteadiness on functional activities in people with vestibular disorders.⁷³

Balance Training

There are many factors to consider when developing an intervention program for balance impairments. Most balance intervention programs require a multisystem approach. For example, an individual who has experienced prolonged bed rest or inactivity following an illness may require a program that includes stretching the lower extremities and trunk to improve postural alignment and mobility; strengthening exercises to improve motor performance; and dynamic, functional balance activities to improve the ability to perform daily activities safely. The following elaborates on the interventions suggested previously (see Table 8.3), which are based on identified deficits in static, dynamic, anticipatory, and reactive control as well as problems involving sensory organization, function, and safety. For specific procedures to address musculoskeletal problems such as strength, joint mobility, flexibility, or posture, refer to the chapters addressing these interventions or to chapters focused on specific regions of the body.

Because balance training often involves activities that challenge the patient's limits of stability, it is important that the therapist takes steps to ensure the patient's safety. Box 8.3 lists safety measures that should be considered and utilized to prevent falls and injuries during therapy.

Static Balance Control

Activities to promote static balance control include having the patient maintain sitting, half-kneeling, tall kneeling, and standing postures on a firm surface.

• More challenging activities include practice in the tandem and single-leg stance (Fig. 8.10), lunge, and squat positions.

• Progress these activities by working on soft surfaces (e.g., foam, sand, grass), narrowing the base of support, moving the arms, or closing the eyes.

• Provide resistance via handheld weights or elastic resistance (Figs. 8.11 and 8.12).

• Add a secondary task (i.e., catching a ball or mental calculations) to further increase the level of difficulty (Fig. 8.13).

Dynamic Balance Control

To promote dynamic balance control, interventions may involve the following.

• Have the patient maintain equal weight distribution and upright trunk postural alignment while on moving surfaces, such as sitting on a therapeutic ball, standing on wobble boards (Fig. 8.14), or bouncing on a mini-trampoline.

• Progress the activities by superimposing movements such as shifting the body weight, rotating the trunk, moving the head or arms (Fig. 8.15).

• Vary the position of the arms from out to the side to above the head (Fig. 8.16).

• Practice stepping exercises starting with small steps, then mini-lunges to full lunges.

• Progress the exercise program to include hopping, skipping, rope jumping, and hopping down from a small stool while maintaining balance.

• Have the patient perform arm and leg exercises while standing with normal stance, tandem stance, and single-leg stance (Fig. 8.17).

Anticipatory Balance Control

Practice anticipatory balance control by performing the following.

• Reach in all directions to touch or grasp objects, catching a ball, or kicking a ball.

• Use different postures for variation (e.g., sitting, standing, kneeling) and throwing or rolling the ball at different speeds and heights (Fig. 8.18).

• Use functional tasks that involve multiple parts of the body to increase the challenge to anticipatory postural control by having the patient lift objects of varying weight in different postures at varying speeds, open and close doors with different handles and heaviness, or maneuver through an obstacle course.

Reactive Balance Control

Train reactive balance control by using the following activities.

• Have the patient work to gradually increase the amount of sway when standing in different directions while on a firm stable surface.

• To emphasize training of the ankle strategy, have the patient practice while standing on one leg with the trunk erect.

• To emphasize training of the hip strategy, have the patient walk on balance beams or lines drawn on the floor; perform tandem stance and single-leg stance with trunk bending; or stand on a mini-trampoline, rocker balance, or sliding board.

• To emphasize the stepping strategy, have the patient practice stepping up onto a stool or stepping with legs crossed in front or behind other leg (e.g., weaving or braiding).

• To increase the challenge during these activities, add anticipated and unanticipated external forces. For example, have the patient lift boxes that are identical in appearance but of different weights; throw and catch balls of different weights and sizes; or while on a treadmill, suddenly stop/start the belt or increase/decrease the speed.

Sensory Organization

Many of the activities previously described can be utilized while varying the reliance on specific sensory systems.

• To reduce or destabilize the visual inputs, have the patient close the eyes, wear prism glasses, or move the eyes and head together during the balance activity.

• To decrease reliance on somatosensory cues, patients can narrow the BOS, stand on foam, or stand on an incline board.

Balance During Functional Activities

Focus on activities similar to the functional limitations identified in the evaluation. For example:

• If reaching is limited, have the patient work on activities, such as reaching for a glass in a cupboard, reaching behind (as putting arm in a sleeve), or catching a ball off center.

• Perform two or more tasks simultaneously to increase the level of task complexity.

• Practice recreational activities the patient enjoys, such as golf, to increase motivation while challenging balance control (Fig. 8.19).

Safety During Gait, Locomotion, or Balance

To emphasize safety, have the patient practice postural sway activities within the person's actual stability limits and progress dynamic activities with emphasis on promoting function. If balance deficits cannot be changed, environmental modifications, assistive devices, and increased family or external support may be required to ensure safety.

Health and Environmental Factors

In addition to exercise and balance training activities, clinicians should address several other factors affecting balance to reduce the risk of falls.⁸⁷

Low Vision

To address low vision issues, encourage regular eye examinations with adjustments to lens prescriptions and cataract surgery, if necessary. Wearing a hat and sunglasses in bright sunlight, taking extra precautions when it is dark, and making sure lights are on when walking about the house at night are other recommendations. Advise patients to avoid using bifocal glasses when walking, because single lens glasses are safest for improving depth perception and contrast sensitivity, especially on stairs.⁸⁶

Sensory Loss

For individuals with sensory loss in the legs, caution them to take extra care when walking on soft carpet or uneven ground and use a cane or other device if necessary. Recommend that they wear firm rubber shoes with low heels. Regular medical examinations should be encouraged to ensure that a patient's blood glucose levels and other factors (i.e., cholesterol, lipids) are under control to minimize damage to sensory nerves from diseases such as diabetes and peripheral vascular disease. Advise patients to seek medical attention if they experience any symptoms of dizziness.

Medications

Patients should be educated about the influence of certain medications, such as sedatives and antidepressants, on their risk of falling. For example, if such medications are used at night as a sleep aid, an individual should take extra precautions when getting up to use the bathroom.

Evidence-Based Balance Exercise Programs for Fall Prevention in the Elderly

Mounting evidence from randomized clinical trials indicates that therapeutic exercise is an effective tool in the prevention of falls, especially if it is incorporated with a comprehensive strategy targeting health, environmental, and behavioral risk factors that contribute to falls.^48,96 The selection of exercises and activities for balance training should be based on two major factors: the person's fall risk and the setting in which the training will take place. Economic and transportation factors also play a role in these decisions. Since people can fall while participating in balance training and exercise programs, it is critical that adequate protections are in place to prevent falls. Based on these issues, the following guidelines are proposed.

• Elderly individuals who have no history of falls and do not have scores that are within the "at risk" category on standardized balance tests should participate in an individual or community-based group exercise program incorporating muscle strengthening, balance, and coordination exercises.

• Individuals who are at risk of falls, based on standardized balance tests, but have not developed a history of falls should participate in individual or group exercise programs in which there are well-trained leaders and support staff who appropriately supervise and guard the person during the activities that challenge balance.

• People who are at risk of falls and have a history of falls require an individually tailored, supervised, exercise program by a physical therapist or physical therapist assistant and, if appropriate, a caregiver who is trained to supervise and guard the person during the home exercise activities. This program may take place in a clinic- or home-based setting.

Home Exercise Program for Reducing Risk of Falls for People at High Risk

The home setting may be the best option for an exercise-based falls prevention program for some people who are at high risk of falls. Reasons why the home may be the best location for such a programs include: 1) the person functions most often in this environment, therefore, the training takes place in the location where falls are most likely to occur; and 2) the person may participate more fully to his or her physical capacity without the stress and fatigue that may be associated with transportation issues.

Otego Home Exercise Program

The Otego Exercise Program^21,44,125 is a cost-effective program for reducing falls for people aged 80 and over. This program consists of an individually tailored, 30-minute leg strengthening and balance training program that is performed at home at least three times per week and is complemented with a walking plan. The program is designed to be performed for 24 weeks under the supervision of physical therapists or health professionals trained by physical therapists.⁴⁴

• The patient receives a booklet with illustrations and instructions on each exercise.

• Ankle weights are used to provide resistance during the leg strengthening exercises that target the muscles that extend and abduct the hip and flex and extend the knee.⁴⁴

  • The amount of resistance should be based on the amount of weight that the person can lift for 8 to 10 repetitions of the exercise before fatiguing. Most people start with 1 or 2 kg (2.2 or 4.4 lb) cuff weights.

  • The goal is for the person to be able to do two sets of 10 repetitions before the amount of weight is increased.

  • The ankle dorsiflexor and plantarflexor muscles are strengthened using body weight as the resistance (Fig. 8.20 and Fig. 8.21).

  • Box 8.4 provides a list of the strengthening exercises in the Otego program.

• The balance training component of the Otego Exercise Program is also tailored to the individual and emphasizes dynamic exercises that are closely related to functional activities (Fig 8.22).⁴⁴ Depending on the ability of the individual, the balance exercises may be performed by holding on to a large, stable piece of furniture or a kitchen counter and progressed by performing the exercises without support (Fig 8.23). Balance training exercises are listed in Box 8.4.

• A walking program is part of the Otego Exercise Program.⁴⁴ People are told to walk for at least 30 minutes per day at their usual pace. The walking plan may be accomplished by taking walks of smaller intervals (e.g., 10 minutes) throughout the day.

Supervised Group Program Incorporating Strengthening, Walking, and Functional Activities

A recent systematic review of the literature concluded that multimodal exercise programs incorporating muscle strengthening, gait, balance, coordination and functional exercises led to greater beneficial effects on balance than usual exercise programs, at least in the short-term.⁶⁶ There was limited evidence for long-term effectiveness. Most exercise programs lasted 3 months and met three times per week for 1 hour.

Box 8.5 provides general guidelines for exercise repetitions, duration of endurance walking, and progression of a supervised group program.⁹⁶

Multisystem Group Exercise Program Incorporating a Circuit of Activities to Address Balance Impairments and Function

Nitz and Choy¹¹² investigated the efficacy of a balance training program that integrated individual and group exercises targeting strength, coordination, sensory systems (vision, perception, vestibular), cognition, reaction time, and static and dynamic stability. Community-residing elderly individuals with a recent history of falls were randomly assigned to two groups. One group participated in the balance training program that addressed multisystem activities. The control group participated in a more traditional group exercise program. Participants in both groups received an educational booklet on how to prevent falls in the home and attended a 1-hour exercise session once a week for 10 weeks. The exercises were led by a physical therapist assisted by one or two students when small group activities (six participants per group) were performed.

After the intervention, both groups reported a reduction in the number of falls. The reduction in falls was greater in the group that performed the circuit training program; they also showed greater improvements in functional tests of the ability to perform activities of daily living. Although the circuit training program devised by Nitz and Choy¹¹² clearly incorporates many important activities to address multiple systems affecting balance, the results should be interpreted with caution, because there was a small sample size and a high proportion of dropouts throughout the study.

Table 8.4 provides the details of the balance exercise program, consisting of circuit training and group activities, from the Nitz and Choy study.¹¹²

Tai Chi for Balance Training

Tai Chi has become a popular form of exercise for balance training. Tai Chi is a traditional Chinese exercise program consisting of a sequence of whole-body movements that are performed in a slow, relaxed manner with an emphasis on awareness of posture alignment and synchronized breathing. The four styles of Tai Chi are Yang, Sun, Chen, and Wu, and they differ in terms of principles, forms, and function. Yang style Tai Chi is the most popular and widely practiced style today and consists of 24 forms (postures and movements).⁸⁸ Tai Chi programs for the elderly may adopt a short form of Tai Chi with only 6 to 12 forms.⁸⁸ During Tai Chi training, participants learn to control the displacement of the body COM while standing and increase their lower extremity strength and flexibility during the regimens of physical movement.²⁷

Some of the characteristics of Tai Chi exercise and the therapeutic rationale for why Tai Chi may affect posture and balance include the following.¹⁵⁷

• The slow, continuous, even rhythm of the movements facilitates sensorimotor integration and awareness of the external environment (see Fig. 8.2).

• The emphasis on maintaining a vertical posture enhances postural alignment and perception of orientation.

• The continuous weight shifting from one leg to the other facilitates anticipatory balance control, motor coordination, and lower-extremity strength.

• Finally, the large dynamic, flowing, and circular movements of the extremities promote joint ROM and flexibility (Fig 8.24). These characteristics should be considered when recommending Tai Chi classes to patients to ensure that instructors are following these principles and that the patients are appropriate for these activities.

Evidence-Based Balance Exercise Programs for Specific Musculoskeletal Conditions

Evidence is growing that specific balance exercise programs can effectively prevent and/or treat balance control deficits associated with lower extremity and trunk injuries and pathologies.

Ankle Sprains

Several systematic reviews have concluded that balance training programs can improve static and dynamic balance and reduce the risk of ankle sprains in individuals with a history of ankle sprains.^58,69,94,158 Successful programs utilized wobble or unstable balance platforms, single-leg stance progressions, and resisted kicks of the uninvolved leg against an elastic band or tubing.^{38,52,93,99,126,155} Programs typically were conducted for at least three times per week throughout a competitive season for prevention or two to three times per week for approximately 6 to 8 weeks post injury.

Anterior Cruciate Ligament Injuries

Proprioceptive and balance training programs either alone or in combination with neuromuscular training that includes lower extremity plyometrics, trunk stabilization, strengthening (refer to Chapter 16), and sport-specific functional training (refer to Chapters 21 and 23) have been shown to reduce risk factors and the incidence of first-time noncontact anterior cruciate ligament (ACL) injuries in athletes.^2,115,143 These proprioceptive and balance training programs frequently consisted of double and single leg balance exercises progressing from firm to unstable surfaces, such as ankle disks, tilt boards, or foam, with variations, such as squatting or catching a ball.^{22, 40, 46, 95} Balance exercises usually were done 10 to 15 minutes daily during preseason training and 3 times a week during the season for prevention.

A balance training program developed by Fitzgerald and colleagues⁴¹ that consisted of multidirectional perturbations manually applied by a therapist while a person stood with one or two legs on tilt or roller boards increased the likelihood by almost five times that a person with acute anterior cruciate ligament injury or ruptures of anterior ligament grafts would return to high-level physical activity compared to those that received a standard program. Treatment in this study was done two to three sessions per week for a total of 10 sessions.

Low Back Pain

Research indicates that proprioceptive or balance training may improve postural control in individuals with low back pain.^{20,39,92,149,150} Specific spinal stabilization exercises consisting of voluntary contractions of deep abdominal muscles reduced pain and disability⁹² and produced immediate and long-term improvements in feedforward postural adjustments in people with chronic nonspecific low back pain (refer to Chapters 15 and 16).^149,150

Cacciatore and associates²⁰ studied the effects of a 6-month, once a week course of 20 lessons in the Alexander Technique (AT), a technique that addresses anticipatory postural adjustments through conscious control of tonic muscular activity, on postural coordination and back pain in a 49-year-old woman with a 25-year history of left-sided, idiopathic low back pain. Before the AT lessons, the patient consistently had asymmetrical automatic postural responses to horizontal force platform movements and poor ability to balance on the left leg. Following the lessons, she had improved postural responses, better standing balance, and decreased low back pain.

Critical Thinking and Discussion

1. A person is experiencing falls when rising from a chair. Using biomechanical principles of balance, what adjustments can the person immediately make to increase his or her stability and prevent falls?

2. Differentiate and describe several balance movements that rely primarily on feedforward or open-loop motor control versus those that utilize closed-loop control.

3. Review the ankle, hip, and stepping strategies and discuss how the strategies are elicited and what key muscles are activated to control balance.

4. Think about the times you have fallen in the past. What activity were you doing at the time that you fell? What musculoskeletal, neurological, and/or contextual factors contributed to the fall occurrence? What were the consequences of the fall? What differences would you expect between your falls and those experienced by an elderly person?

5. Differentiate and discuss treatment activities that you would use to train static, dynamic, anticipatory, reactive, and sensory organization aspects of balance control. Provide examples of how you would progress each of the activities.

6. For an elderly person with a history of falls, what aspects of the home environment might need to be modified to maximize the individual's safety and independence?

7. The success of balance training programs depends on the compliance by the patient. What strategies would you use to increase the likelihood that a person would adhere to a home exercise program and ensure that his or her treatment outcomes are attained? Refer to Chapter 1 for discussion on teaching strategies for effective exercise.

Laboratory Practice

1. With a partner, mount a yardstick on the wall at the person's shoulder height. Measure the maximum amount of anterior and posterior sway by recording the maximum shoulder displacement during a 30-second period of quiet stance in each of the following conditions.

   • Standing on a firm surface with feet together, arms on hips, and eyes open.

   • Standing on a firm surface with feet together, arms on hips, and eyes closed

   • Standing on a soft foam surface with feet together, arms on hips, and eyes open

   • Standing on a soft foam surface with feet together, arms on hips, and eyes closed

   For each of the conditions, what sensory inputs are available to the person for maintaining balance? How does the amount of sway vary with each condition and why?

2. With a partner, observe body movement during the following activities.

   • Standing with feet shoulder width apart, perform self-initiated forward and backward body sways progressing from small to large amplitudes.

   • Standing with feet apart, have your partner place his or her hand on your sternum and nudge you backward gently and then again with a larger force.

   • Standing with the feet placed heel to toe, have your partner gently nudge you backward.

   • Put on ankle-foot orthoses or ski boots that restrict ankle movements and have your partner gently nudge you backward.

   Which movement strategy is elicited with each activity and why?

3. Practice performing treatment activities that you would use to train static, dynamic, anticipatory, reactive, and sensory organization aspects of balance control as described in Table 8.2. Progress each of the activities to maximally challenge your balance.

Case Studies

1. A 20-year-old male soccer player sustained a right mid-tibial fracture in a motor vehicle accident and was required to wear a long-leg rigid cast for 6 weeks. You are seeing the patient 1 week after cast removal for physical therapy. He would like to return to playing soccer but is currently unable to maintain balance on his right leg to kick a soccer ball. What underlying impairments might be causing this individual's balance problems, and how would you design an exercise program that would allow him to reach his goals?

2. A 75-year-old woman fell in her bathtub and sustained a right pelvic fracture, requiring bed rest for 2 weeks. You are seeing the patient in her home following her hospital discharge. She has generalized weakness, deconditioning, is unsteady on her feet, and is fearful of falling. Currently, she is using a walker for ambulation. Prior to her fall, she was completely independent in all activities of daily living and enjoyed going on walks in her neighborhood in the evenings. Design a progressive balance program for this woman to restore her to her prior level of functioning.

3. A 70-year-old retiree has had bilateral knee replacement surgeries. He would like to resume his favorite hobby of boating but lacks confidence in his ability to balance under dynamic conditions. Design an exercise and balance training program that will help him return to his recreational pursuits. What suggestions do you have to increase his safety when boating? What if his hobby was golfing instead of boating? Compare and contrast the activities and exercises you would prescribe for these two different issues.

4. A 56-year-old obese woman with diabetes is being treated for low back pain. She reports unsteadiness when walking, particularly in darkened environments. She has difficulty maintaining her balance during Conditions 2, 3, 5, and 6 of the CTSIB test. What factors could be contributing to her unsteadiness? Design an exercise program that addresses her balance impairments.

5. An active, vibrant 70 year-old-female seeks your advice on how to best maintain her health and fitness. What are the major components of a comprehensive exercise program for her? Give examples of exercises she should include.