Balance/Postural Control

Question 1

Define postural control

Answer 1

• the act of maintaining, achieving, or restoring a state of balance on a support surface during any functional task that involves movement

Question 2

Stages of motor control

Answer 2

• movement
• stability
• controlled mobility
• skilled movement

Question 3

Where is the center of mass

Answer 3

• at 2nd sacral vertebra in anatomical standing

Question 4

Line of gravity through the body in standing

Answer 4

• anterior to ankle
• anterior to knee
• posterior to hips
• anterior to thoracic vertebrae
• anterior to shoulders

Question 5

Describe limits of stability/ cone of stability

Answer 5

• max distance one can lean/reach without changing base of support & without loss of balance

Question 6

Steady state balance

Answer 6

• quite sitting/standing

Question 7

Reactive balance

Answer 7

• balance reactions in response to brief perturbations/movement in COG
• mostly use feedback mechanisms in response to sensory inputs
• use some automated motor control strategies here

Question 8

Proactive balance

Answer 8

• postural adjustments in anticipation of voluntary movements that will move COG
• use feedforward mechanisms

Question 9

Postural alignment

Answer 9

• perfect alignment when line of gravity passes through structures as expected
• minimal muscle activity required

Question 10

Steadiness/postural sway

Answer 10

• ability to maintain COM/LOG at place with minimal movements
• can be measured by center of pressure movements on force plates
• normally exhibit small postural sway during standing
• sway envelope = path of excursion of the center of pressure during quite standing

Question 11

Fixed support strategies

Answer 11

• used to control center of mass over fixed base of support, center of mass remains within limits of stability
• ankle, hip, and suspension strategies

Question 12

Ankle strategy

Answer 12

• move COM of body as a block about ankle joints
• used when sways are small/slow
• muscles are activated distal to proximal
• during forward sway -> gastroc, hamstrings, & paraspinals
• during backward sway -> tib ant., quads, & abdominals
• used on firm support surface

Question 13

Hip strategy

Answer 13

• moves COM by flexing/extending/ABD/ADD hips
• used with larger/faster sway
• muscles activated proximal to distal
• forward sway -> abdominals & quads
• backward sway -> paraspinals & hamstrings
• used when support surface is small/narrow/compliant

Question 14

Suspension strategy

Answer 14

• moves COM down by flexing hips/knees & flexing trunk
• may progress to squating

Question 15

Change in support strategies

Answer 15

• used to control COM over moving base of support when COM moves out of loss of stability
• stepping & reaching/grasping strategies

Question 16

Stepping strategy

Answer 16

• brings COM back within loss of stability by taking a rapid step in the direction of the destabilizing force
• recruited in response to fast large perturbations when ankle/hip strategies are not adequate to recover postural control
• not a strategy of last resort it is recruited quickly ahead of ankle/hip strategies if CNS perceives a big perturbation

Question 17

Reaching/grasping strategy

Answer 17

• bring COM within loss of stability by extending base os support by reaching/grasping using UE

Question 18

What sensory systems are involved in balance

Answer 18

• visual
• somatosensory
• vestibular

Question 19

Visual system

Answer 19

• has roles in both feedforward and feedback balance mechanisms
• Feedforward: focal vision (central vision, to see obstacle ahead of you & react beforehand & needed for proactive/anticipatory postural control
• Feedback: ambient vision (focal & peripheral vision), to regain postural control after perturbations & needed for reactive postural control

Question 20

Somatosensory system

Answer 20

• information from touch receptors and proprioceptive sensations from muscles, tendons, and joints
• has roles in both feedforward and feedback mechanisms
• provide info about orientation & movement of body in relation to support surface

Question 21

Vestibular system

Answer 21

• provides CNS with info about position.movement of head with respect to gravity/inertial forces
• info about linear/angular acceleration
• functions to stabilize gaze during head movements, regulates tone in postural/antigravity muscles

Question 22

Sensory Organization Test (SOT) scoring

Answer 22

• 1 = minimal sway
• 2 = mild sway
• 3 = moderate sway
• 4 = loss of balance

Question 23

Modified Clinical Test for Sensory Integration of Balance (mCTSIB)

Answer 23

• performs standing on stable surface eyes open then closed
• performs standing on unstable surface eyes open then closed
• does not test/perform inaccurate visual input

Question 24

Balance tests for steady state balance

Answer 24

• single limb stance time (30s)
• Romberg test (feet together 30s)
• CTSIB/mCTSIB

Question 25

Balance tests for anticipatory balance

Answer 25

• functional reach test
• multi-directional reach test
• star excursion balance test/Y-balance test

Question 26

Balance tests for reactive balance

Answer 26

• retropulsive pull test (pull pt backwards)
• push and release test (0 = recovers with 1 step, 1 = 2-3 small steps, 2 = 4 or more steps, 3 = multiple steps & needs assistance to prevent fall, 4 = falls w/o attempting steps)

Question 27

Balance tests for sitting balance

Answer 27

• Static sitting balance: postural symmetry, pelvic tilt, base of support, biomechanical constraints, & sensory orientation
• Dynamic sitting balance: stability limits & verticality, anticipatory postural control, and reactive postural control

Question 28

Assessment of balance at impairment level

Answer 28

• Motor systems: ankle, hip, and step strategies
• Sensory systems: stable to unstable surface
• Cognitive systems: dual task testing

Question 29

Seated balance tests

Answer 29

• sitting balance assessment
• FIST (function in sitting test)
• SATCo

Question 30

Standing balance tests

Answer 30

• FRT/MDRT (functional reach test)
• Romberg/Sharpened Romberg (feet together/tandem)
• SLST (single limb stance time)

Question 31

Combined sitting & standing activities to assess balance

Answer 31

• TUG (time up & go; more than 13s is cut off for fall risk)
• 5TSTS (5x sit to stand)
• 30SCST (30s sit to stand)
• PASS (postural assessment seated/standing)
• BESTest (cut off for fall risk is <69%)/miniBESTtest (cut off <23/28)
• DGI (dynamic gait index)
• FGA (functional gait assessment)

Question 32

How do you improve balance

Answer 32

• appropriate intensity and volumes
• need to work at the levels where patients experience some loss of balance

Question 33

Interventions for static/steady state balance control

Answer 33

• having patient maintain progressively difficult static postures: sitting, quadruped, half kneeling, tall kneeling, standing, lunge, squat positions

Question 34

How to train reactive balance control

Answer 34

• requires external perturbations

Question 35

How to train anticipatory balance control

Answer 35

• requires change of posture during functional activities
• example: reach in all directions to touch or grasp objects, pick objects from floor, catch ball, tap balloon, or kick ball

Question 36

Combined reactive and anticipatory balance control activities

Answer 36

• seated reaching with perturbations
• gait with head turns and perturbations
• sit to stands with perturbations