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
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
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
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