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Overview Of Balance Overview Of Balance Laura Morris, P.T. Laura Morris, P.T. University of Pittsburgh Medical University of Pittsburgh Medical Center Center

Overview Of Balance Laura Morris, P.T. University of Pittsburgh Medical Center

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Overview Of BalanceOverview Of Balance

Laura Morris, P.T.Laura Morris, P.T.

University of Pittsburgh Medical CenterUniversity of Pittsburgh Medical Center

SESSION OBJECTIVESSESSION OBJECTIVES

Describe the important terminology used in the study of balance and mobility

Identify the multiple systems that contribute to postural stability

Describe the major age-related changes in balance and mobility

Biomechanics

Motor Coordination

SensoryOrganization

Joint RangeFlexibility ToneTone Temporal PatternTemporal Pattern

SpatialSpatial

Multiple TaskingMultiple Tasking

AdaptationAdaptation

Predictive Predictive Central SetCentral Set

Sensory StrategiesSensory Strategies

Limits of StabilityLimits of Stability

VerticalityVerticality

MotionMotionPerceptionPerception

DetectionDetectionof Instabilityof Instability

StrengthStrength

MorphologyMorphology

Subcomponents of Postural StabilitySubcomponents of Postural Stability

Horak, 1997Horak, 1997

Systems Contributing to Control of Balance

Sensory peripheral and central

Motorincluding musculoskeletal

Cognitive/Attention

Important TerminologyImportant TerminologyImportant TerminologyImportant TerminologyBalance

• A process by which we control the body’s Center of Mass (COM) with respect to the base of support (BOS), whether it is stationary or moving. (standing quietly, leaning in space, walking)

Mobility• The ability to independently and safely move oneself

from one place to another. (transfers, climbing stairs, walking, running)

Important TerminologyImportant Terminology

Anticipatory Postural Control• Actions that can be planned in advance

(negotiating obstacles, moving over uneven terrain in good lighting)

Reactive Postural Control• Actions cannot be planned in advance. Occur

in response to a set of environmental conditions(stepping in a hole, being unexpectedly bumped)

Important TerminologyImportant Terminology

Stability Limits• The maximum distance leaned in any

direction without changing the BOS• Boundaries will vary based on

individual’s abilities, task being performed, and environmental constraints.

Postural Control Strategies

Ankle• Used to control sway when standing quietly

or swaying over small distance in forward-backward direction

• Requires adequate Range Of Motion (ROM) and strength in muscles surrounding ankle joint.

• Sufficient level of sensation in feet and ankles also important.

Postural Control Strategies

Hip• Used when surface below feet is narrow

or compliant or, when swaying closer to stability limits.

• Requires adequate level of strength and ROM in hip region.

Postural Control StrategiesPostural Control Strategies

Step• Used when the boundaries of stability are

exceeded• Requires sufficient level of lower body

strength and power, adequate ROM in hip.

• Adequate level of function in sensory and motor systems

Age-Related Changes in the

Older Adult

Commonly Observed Commonly Observed ImpairmentsImpairments

Peripheral SensoryPeripheral SensoryCentral SensoryCentral SensoryCentral MotorCentral MotorPeripheral MotorPeripheral Motor

Reduced Vision Reduced Vision • AcuityAcuity• Contrast sensitivity Contrast sensitivity • Depth perceptionDepth perception

Effect on Motor Behavior?Effect on Motor Behavior?• Ability to accurately perceive and/or Ability to accurately perceive and/or

anticipate changes in surface and obstaclesanticipate changes in surface and obstacles• Navigation in low or changing lightNavigation in low or changing light

Peripheral Sensory Peripheral Sensory ImpairmentsImpairments

Common Eye Diseases

Courtesy of the National Eye Institute, National Institute of Health

Peripheral Sensory ImpairmentsPeripheral Sensory Impairments

Reduced and/or slowedReduced and/or slowed sensation in sensation in touch receptorstouch receptors• Increase in vibration thresholdIncrease in vibration threshold• Decreased proprioceptionDecreased proprioception

Effect on Motor Behavior?Effect on Motor Behavior?• Ability to feel quality of contact with Ability to feel quality of contact with

support surfacesupport surface• Static and changing position of limbs in Static and changing position of limbs in

space.space.

Peripheral Sensory Impairments

Reduced Vestibular FunctionReduced Vestibular Function• Loss of hair cellsLoss of hair cells• Reduction in Vestibulo-ocular reflex (VOR)Reduction in Vestibulo-ocular reflex (VOR)

Effect on Motor Behavior?Effect on Motor Behavior?• Head position and/or movement of head in spaceHead position and/or movement of head in space• Resolution of sensory conflictResolution of sensory conflict• Balance when vision and somatosensation Balance when vision and somatosensation

absent or distorted.absent or distorted.

Central Sensory Central Sensory ImpairmentsImpairments

Visually dependentVisually dependent Poor integration of sensory inputsPoor integration of sensory inputs Distorted perception of true vertical Distorted perception of true vertical

and/or horizontaland/or horizontal Slowed processing of sensory Slowed processing of sensory

feedbackfeedback

Central Motor ImpairmentsCentral Motor Impairments

Increased planning timeIncreased planning time Increased movement timesIncreased movement times Strategy selection problemsStrategy selection problems Increased variation in temporal Increased variation in temporal

sequencing of musclessequencing of muscles Loss of anticipatory controlLoss of anticipatory control

Effect on Motor Behavior? Slower to initiate and execute

movements, particularly in complex sensory environments

Inappropriate choice of movement strategies

Slowed gait speed, hesitation during obstacle negotiation.

Overall quality of motor coordination

Peripheral Motor Peripheral Motor ImpairmentsImpairments

Decreased joint range of motionDecreased joint range of motion Decreased strength Decreased strength andand power in power in

lower body muscle groupslower body muscle groups Decreased strength in upper Decreased strength in upper

body muscle groupsbody muscle groups Decreased muscular enduranceDecreased muscular endurance

Effect on Motor Behavior?

Performance of basic, intermediate, and advanced activities of daily living (ADLs).

Slowed and/or ineffective responses to sudden loss of balance

Quality of motor performance Increased fatigue

Cognitive ImpairmentCognitive Impairment

Reduction in Working MemoryReduction in Working Memory Reduced attentional abilitiesReduced attentional abilities

Multiple TasksMultiple TasksCertain sensory environmentsCertain sensory environments

Reduction in fluid intelligenceReduction in fluid intelligence

Cognitive Impairment

Fluid Intelligence: • Thinking “on the fly” (problem solving)

Crystallized Intelligence: • What you know (vocabulary)

Task Demands

Environment IndividualCapabilities

SurfaceType

VisualFlow

SeatedStandingMoving

Single Multiple

Strength

ROM

Sensory Loss

Cognition

Lighting

Individual Capabilities: NellieIndividual Capabilities: Nellie

Strength/Motor control mildly impaired in both lower extremities

Sensation is within normal limits (WNL) for her age but vision is impaired

Safety judgment and cognition poor- Not capable of running down stairs, but routinely attempts it anyway

Task DemandsTask Demands

Research Evidence:• Attentional demands for postural stability

increase in older adults

• Inability to divide attention between tasks and postural stability is a contributing factor to falls (e.g., carrying groceries while chatting with friend)

Task Demands: JudyTask Demands: Judy

Unable to climb or descend stairs without effort and fear

Experiences difficulty talking with her husband as she does the dishes

No longer works in the garden

Environmental Constraints

To limit or not to limit, that is the question… Decreased environmental hazards Less

engaging in activities in community short term reduced exposure less falls

HOWEVER, long term reduced exposure deconditioning, less self confidence MORE FALLS!

Environmental Constraints: Billie

Widowed one year ago Gave dog away as she didn’t feel safe walking

her Had to give up volunteer positions when

husband fell ill, has not returned Doesn’t feel safe walking outside anymore,

won’t go out at night

Can Age-Related Changes be reversed?

YES, if: Intervention targets source(s) of

balance-related problems Repeatedly exposes older adults to

changing task demands and environmental constraints