Balance and coordination in human bodies

Balance and coordination, gait vertigo in humans

1. Balance & Postural Equilibrium

2. What is Balance? Technically defined as the ability to maintain the center-of-gravity (COG) of an object within its base-of-support (BOS)

3. Transition - Static to Dynamic BOS Heel-to-heel distance will decrease Feet come together toward midline Toe-to-midline distance will decrease Reflects “toe-in” Overall effect - BOS narrows

4. The Effect of a Narrowed BOS Chances of COG falling within BOS decrease Subject becomes less (un-) balanced COG moves forward of BOS - precursor event to walking Foot will be advanced to extend the dynamic BOS

5. STABILITY MOBILITY Mass large small Position of COG low high Size of BOS large small Vertical projection of COG to point near center of BOS to point near boundary of BOS

6. A Systems Model of Balance

7. Stability & Balance Result of interaction of many variables (see model) Limits of Stability - distance in any direction a subject can lean away from mid-line without altering the BOS Determinants: Firmness of BOS Strength and speed of muscular responses Range: 8 anteriorly; 4 posteriorly

8. Limits of Stability

9. Model Components Musculoskeletal System ROM of joints Strength/power Sensation Pain Reflexive inhibition Abnormal muscle tone Hypertonia (spasticity) Hypotonia

10. Musculoskeletal System

11. Model Components Goal/Task Orientation What is the nature of the activity or task? What are the goals or objectives?

12. Model Components Central Set Past experience may have created “motor programs” CNS may select a motor program to fine-tune a motor experience

13. Nervous System

14. Model Components Environmental Organization Nature of contact surface Texture Moving or stationary? Nature of the “surrounds” Regulatory features of the environment (Gentile)

15. Contextual Effects

16. Model Components Motor Coordination Movement strategies Feedback & feed forward control Adjustment/tuning of strategies

17. Strategies to Maintain/Restore Balance Ankle Strategy Weight Shift Strategy (Lateral) Suspension Strategy Hip Strategy Stepping Strategy Combine Strategy Strategies are automatic and occur 85 to 90 msec after the perception of instability is realized

18. Ankle Strategy Used when perturbation is Slow Low amplitude Muscles recruited distal-to-proximal Head movements in-phase with hips

19. Hip Strategy Used when perturbation is fast or large amplitude Surface is unstable Muscles recruited proximal-to-distal Head movement out-of-phase with hips

20. Stepping Strategy Used to prevent a fall Used when perturbations are fast or large amplitude -or- when other strategies fail BOS moves to “catch up with” BOS

21. Suspensory Strategy Forward bend of trunk with hip/knee flexion - may progress to a squatting position COG lowered

22. Motor Strategies

23. Model Components Sensory Organization Balance/postural control via three systems: Somatosensory Visual Vestibular

24. Somatosensory System Dominant sensory system Provides fast input Reports information Self-to-(supporting) surface Relation of one limb/segment to another Components Muscle spindle Muscle length Rate of change GTOs Monitor tension Joint receptors Mechanoreceptors Cutaneous receptors

25. Visual System Reports information Self-to-(supporting) surface Head position Keep visual gaze parallel with horizon Subject to distortion Components Eye and visual tracts Thalamic nuclei Visual cortex Projections to parietal and temporal lobes

26. Vestibular System Not under conscious control Assesses movements of head and body relative to gravity and the horizon (with visual system) Resolves inter-sensory system conflicts Gaze stablization Components Cerebellum Projections to: Brain stem Ear

27. Assessment Static balance Anticipatory postural control Reactive balance Dynamic balance

28. Assessment Tools Static Balance Assessment Single-Leg Stance Test Rhomberg’s Test Stork Stand Test

29. Static Balance Assessment One Leg Stance Test Single Leg Stance Criteria The ability to maintain SLS generally decreases with increasing age (Bohannon et. al, 1985; Ekdahl . al, 1989). Single leg stance has been shown to improve over the course of 6 months of rehabilitation (Judge et. al, 1993)

30. Static Balance Assessment One Leg Stance Test Instructions for the Patient (Eyes Open, SLS): Stand on one leg, place your arms across your chest with your hands touching your shoulders and do not let your legs touch each other. Look straight ahead with your eyes open and focus on an object about 3 feet in front of you. Ideally do this with the shoes off. Criteria to stop timing the test: The legs touched each other, the feet moved on the floor, their foot touches down, or the arms moved from their start position. Should maintain for 10 sec

31. Static Balance Assessment One Leg Stance Test Instructions for the Patient (Eyes Closed, SLS): Stand on one leg, place your arms across your chest with your hands touching your shoulders and do not let your legs touch each other. Close your eyes once you have gotten in position. Ideally do this with the shoes off and be about 3 feet from any wall. Criteria to stop timing the test: The legs touched each other, the feet moved on the floor, their foot touches down, the eyes open during the eyes closed test, or the arms moved from their start position. Should maintain for 10 sec

32. Static Balance Assessment Rhomberg’s Test Rhomberg's test or the Rhomberg maneuver is a test used in a neurological examination, and also as a test for drunken driving Procedure Ask the subject to stand erect with feet together and eyes closed. Try to stay in this position for 30 sec Sensory ataxia Motor ataxia

33. Stork Stand Test

34. Static Balance Assessment Stork Stand Test Criteria & Result

35. Assessment Tools Anticipatory balance assessment Functional Reach Test Multidirectional Reach Test Observations of patient catching ball, opening doors, lifting objects of different weights

36. Anticipatory balance assessment Functional reach Test Requirements: The patient must be able to stand independently for at least 30 seconds without support, and be able to flex the shoulder to at least 90 degrees.

37. Anticipatory balance assessment Functional reach Test Age related norms for the functional reach test: Interpretation: A score of 6 or less indicates a significant increased risk for falls. A score between 6-10 inches indicates a moderate risk for falls

38. Anticipatory balance assessment Multidirectional reach Test This is just an extension of FRT Patient standing Movement is checked by swaying Forward Backward sideways

39. Assessment Tools Reactive balance assessment Backward Release

40. Reactive balance assessment Backward Release Procedure Patient is asked to stand with feet shoulder width apart. Therapist places their hand between the patient’s scapulae. Client is asked to “lean back against hand.” Once the patient is leaning backwards into the therapist’s hand, the therapist unexpectedly removes the support

41. Reactive balance assessment Backward Release Scoring Steadies self independently Number of steps taken: Requires physical assistance not to fall Unable to perform The maneuver is inappropriate (e.g., extreme anxiety) unsafe (e.g., obesity) to be performed on a specific patient.

42. Reactive balance assessment Backward Release Warning! This Test is Dangerous. Do Not Perform This Test If You Will Be Unable To Catch The Patient D O N ’T T R Y T H I S A T H O M E

43. Assessment Tools Dynamic Balance Assessment Berg Balance Scale Tinetti Performance-Oriented Mobility Assessment (POMA) Timed Up and Go Test (TUG)

44. Dynamic Balance Assessment Berg’s Balance Scale Description: 14-item scale designed to measure balance of the older adult in a clinical setting. Equipment needed: Ruler, two standard chairs (one with arm rests, one without), footstool or step, stopwatch or wristwatch, 15 ft walkway Completion: Time: 15-20 minutes Scoring: A five-point scale, ranging from 0-4. “0” indicates the lowest level of function and “4” the highest level of function. Total Score = 56 Interpretation : 41-56 = low fall risk 21-40 = medium fall risk 0 –20 = high fall risk

45. Timed Get Up and Go Test Instructions: The person may wear their usual footwear and can use any assistive device they normally use. 1. Have the person sit in the chair with their back to the chair and their arms resting on the arm rests. 2. Ask the person to stand up from a standard chair and walk a distance of 10 ft. (3m). 3. Have the person turn around, walk back to the chair and sit down again. Timing begins when the person starts to rise from the chair and ends when he or she returns to the chair and sits down.

46. The person should be given 1 practice trial and then 3actual trial. The times from the three actual trials are averaged. Predictive Results Seconds Rating <10 Freely mobile <20 Mostly independent 20-29 Variable mobility >20 Impaired mobility