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

2. SESSION 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

3. Biomechanics Motor Coordination Sensory Organization Joint Range FlexibilityTone Temporal Pattern Spatial Multiple Tasking Adaptation Predictive Central Set Sensory Strategies Limits of Stability Verticality MotionPerception Detection of Instability Strength Morphology Subcomponents of Postural Stability Horak, 1997

4. Systems Contributing to Control of Balance Sensory peripheral and central Motor including musculoskeletal Cognitive/Attention

5. Important Terminology Balance 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)

6. Important 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)

7. Important 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.

8. 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.

9. 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.

10. Postural 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

11. Age-Related Changes in the Older Adult

13. Commonly Observed Impairments  Peripheral Sensory  Central Sensory  Central Motor  Peripheral Motor

14.  Reduced Vision Acuity Acuity Contrast sensitivity Contrast sensitivity Depth perception Depth perception  Effect on Motor Behavior? Ability to accurately perceive and/or anticipate changes in surface and obstacles Ability to accurately perceive and/or anticipate changes in surface and obstacles Navigation in low or changing light Navigation in low or changing light Peripheral Sensory Impairments

15. Common Eye Diseases Courtesy of the National Eye Institute, National Institute of Health

16. Peripheral Sensory Impairments Reduced and/or slowedsensation in touch receptors Reduced and/or slowed sensation in touch receptors Increase in vibration threshold Increase in vibration threshold Decreased proprioception Decreased proprioception Effect on Motor Behavior? Ability to feel quality of contact with support surface Ability to feel quality of contact with support surface Static and changing position of limbs in space. Static and changing position of limbs in space.

17. Peripheral Sensory Impairments  Reduced Vestibular Function Loss of hair cells Loss of hair cells Reduction in Vestibulo-ocular reflex (VOR) Reduction in Vestibulo-ocular reflex (VOR)  Effect on Motor Behavior? Head position and/or movement of head in space Head position and/or movement of head in space Resolution of sensory conflict Resolution of sensory conflict Balance when vision and somatosensation absent or distorted. Balance when vision and somatosensation absent or distorted.

18. Central Sensory Impairments  Visually dependent  Poor integration of sensory inputs  Distorted perception of true vertical and/or horizontal  Slowed processing of sensory feedback

19. Central Motor Impairments  Increased planning time  Increased movement times  Strategy selection problems  Increased variation in temporal sequencing of muscles  Loss of anticipatory control

20. 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

21. Peripheral Motor Impairments  Decreased joint range of motion  Decreased strength and power in lower body muscle groups  Decreased strength in upper body muscle groups  Decreased muscular endurance

22. 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

23. Cognitive Impairment  Reduction in Working Memory  Reduced attentional abilities  Multiple Tasks  Certain sensory environments  Reduction in fluid intelligence

24. Cognitive Impairment  Fluid Intelligence: Thinking “on the fly” (problem solving)  Crystallized Intelligence: What you know (vocabulary)

26. Individual 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

27. Task 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)

28. Task 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

29. 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!

30. 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

31. 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