regaining balance & equilibrium.ppt

7/27/2019 Regaining Balance & Equilibrium.ppt

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Balance & Postural

Equilibrium



Factors impacting balanceMuscular weakness

Proprioceptive deficitsROM deficits



Terminology

Balance - Process of maintaining body’s CoG within base of

support Body’s CoG rests slightly above the pelvis Ability to align body segments against gravity to maintain or move

the body within the available base of support without falling (Kisner & Colby, 2002, 4th ed.)

Strength is emphasized before proprioception in rehab becausestrength influences balance

Postural equilibrium - broader term that incorporatesalignment of joint segments Maintaining CoG (Center of Gravity) within the limits of stability (LOS)

Proprioception – body’s ability to transmit position sense,interpret info & respond consciously/unconsciously to stimulation

Coordination – smooth pattern of activity is producedthrough a combo of muscles acting together withappropriate intensity & timing

Agility – ability to control the direction of a body orsegment during rapid movement



Postural Control System

3 Components of the system

Sensory detection of body motions

Visual

Vestibular

Somatosensory inputs

Integration of sensorimotor information within theCNS

Execution of musculoskeletal responses

Balance is both a static & dynamic process



Control of Balance Tall body vs. Small base of support

Balance relies on network of neural connections

Postural control relies on feedback

CNS involvement Sensory organization

Determines timing, direction & amplitude of correction

based on input System relies on one sense at a time for orientation

Muscle coordination Collection of processes that determine temporal

sequencing & distribution of contractile activity



Sensory Input Vision

Measures orientation of eyes & head in relation to surrounding objects Helps maintain balance

Vestibular Provides info dealing with gravitational, linear & angular accelerations of

the head with respect to inertial space Minor role when visual & somatosensory systems are operating correctly

Somatosensory Provides info concerning relative position of body parts to support surface

& each other

Somatosensation = Proprioceptive system

Specialized variation of the sensory modality of touch, encompassing jointsense (kinesthesia) & position

Process

Input from mechanoreceptors Stretch reflex triggers activation of muscles about a joint because of

perturbation

Results in muscle response to compensate for imbalance andpostural sway

Muscle spindles sense stretch in agonist, relay information afferently tospinal cord

Information is sent back to fire muscle to maintain postural control



Body position inrelation to gravity isdetected by sensoryinput

Balance movementsinvolve a number of joints

Ankle

Knee Hip

Coordinatedmovement alongkinetic chain



Prentice, 2004, 4th ed.



Balance relating to the CKC

Kinetic chain Each moving segment transmits forces to every other segment Maintaining equilibrium involves the closed kinetic chain

(foot = distal segment fixed beneath base of support)

Automatic postural movements Determined via indirect forces created by muscles on

neighboring joints Series of joint strategies are involved to coordinate movement

Injury to joints or corresponding muscles can result in loss of appropriate feedback

Steadiness - Ability to keep body as motionless aspossible Measure of postural sway



Postural sway Deviation from Center of Pressure, Balance & Vertical Force (CoP, CoB,

or CoF)

Determined using mean displacement, length of sway path, lengthof sway area, amplitude, frequency and direction relative to CoP

Symmetry - Ability to distribute weight evenly between 2 feet in

upright stance. Measures: Center of Pressure (CoP)

Center of distribution of the total force applied to thesupporting surface

Center of Balance (CoB)

Point between feet where the ball & heel of each foot has25% of the body weight

Relative weight positioning

Center of Vertical Force (CoF)

Center of vertical force exerted by the feet against the

support surface



BalanceDisruption

Balance Deficiencies - Inappropriate interaction

among 3 sensory inputs

2 Factors that Disrupt Balance

Position of CoG relative to base of support is notaccurately sensed

Automatic movements required to maintain the CoGare not timely/effective

In the event of contact, the body must be ableto determine what to do in order to control CoG Joint mechanoreceptors initiate automatic postural

response



Selecting Movement Strategies

during Balance Disruption

Joints (Ankle, Knee & Hip) involved allowfor a wide variety of postures that can beassumed in order to maintain CoG

Forces exerted by pairs of opposing muscles at a jointto resist rotation (joint stiffness)

Resting position & joint stiffness are altered

independently due to changes in muscle activation Myotatic or Stretch Reflex is earliest mechanism for

activating muscles due to externally imposed jointrotation



Ankle Strategy

Shifts CoG by maintainingfeet & rotating body at arigid mass about the ankle joints Gastrocnemius or tibialis

anterior are responsiblefor torque production

about ankle Anterior/posterior sway

is counteracted bygastrocnemius & tibialisanterior, respectively

Effective for slow CoGmovements when base of support is firm & withinLOS

Also effective when CoG isoffset from center

Hip Strategy

Relied upon more heavilywhen somatosensory lossoccurs & forward/backwardperturbations are imposedor support surface lengthsare altered

Aids in control of motionthrough initiation of large & rapid motions at the hipwith anti-phase rotation of ankle

Effective when CoG is nearLOS perimeter & when LOS

boundaries are contractedby narrower base of support



Stepping Strategy Utilized when CoG is displaced beyond LOS

Step or stumble is utilized to prevent a fall

Instance of musculoskeletal abnormality

Damaged tissue result in reduced joint ROM causing adecrease in the LOS & placing individual at a greater risk for fall

Research indicates that sensory proprioceptive function isaffected when athletes are injured



Assessmentof Balance

Subjective

Assessment Romberg Test –

traditionalassessment

Balance ErrorScoring System

(BESS)

Prentice, 2004,

4th ed.Google Images



Semi-dynamic & dynamic tests functional reach tests

timed agility tests

carioca

hop test Timed T-band kicks

Timed balance beam walks (eyes open & closed)



Objective Assessment

Balance systems Provide for quantitative assessment & training static &

dynamic balance

Easy, practical & cost-effective

Utilize to assess: Possible abnormalities due to injury

Isolate various systems that are affected

Develop recovery curves based on quantitativemeasures in order to determine readiness to return

Train injured athlete Computer interfaced force-plate technology

Vertical position of CoG is calculated

Vertical position of CoG movement = indirect measureof postural sway



Force plate measures

Steadiness, symmetry,dynamic stability

Total force applied tothe platform fluctuatesdue to body weight andinertial effects of body

movement Forces based on motion

of CoG

Allows for static & dynamic posturalassessment

Single or double legstance, eyes opened orclosed

Moving visual surroundfor sensory isolation &

interaction

Prentice, 2004,

4th ed.



Dynamic stability - Ability to transfer

vertical projection of CoG around a stationarysupporting base

Perception of safe limit of stability

Utilization of external perturbation Some are systematic while others are

unpredictable & determined via changes in subjectsway

Athlete should maintain their CoP near A-P and M-L midlines



Injury & Balance

Stretched/damaged ligaments fail to provideadequate neural feedback, contributing todecreased balance & proprioception

May result in excessive joint loading

Could interfere with transmission of afferent impulses

Alters afferent neural code conveyed to CNS

Decreased reflex excitation

Caused via a decrease in proprioceptive CNS input

May be the result of increased activation of inhibitoryinterneurons within the spinal cord

All of these factors may lead to progressivedegeneration of joint & continued deficits in jointdynamics, balance & coordination



Ankles Joint receptors believed to be damaged during injury to

lateral ligaments Less tensile strength when compared to ligament fibers

Results in deafferentation and signaling via afferentpathways

Articular deafferentation – reason behind balance

training in rehabilitation

Orthotic & bracing intervention Enhancement of joint mechanoreceptors to detect

perturbations & provide structural support for detecting & controlling sway

Modify movement strategies to enhance proprioceptiveinput

Altered biomechanical alignment – alters somatosensorytransmission



Knee Injuries Ligamentous injury has been shown to alter

joint position detection

ACL deficient subjects with functional instabilityexhibit this deficit which persist to some degree

after reconstruction

May also impact ability to balance on ACLdeficient leg

More dynamic testing may incorporateadditional mechanoreceptor input – resultsmay be more definitive



Head Injury

Balance has been utilized at a criterionvariable

Additional testing is necessary in addition tobalance & sensory techniques

Postural stability deficits Deficits may last several days post-injury

Result of sensory interaction problem - visualsystem not used effectively

Objective balance scores can be used todetermine recovery curves for making returnto play decisions



BalanceTraining

Vital for successful return to competition fromlower leg injury Possibility of compensatory weight shifts and gait

changes resulting in balance deficits

Functional rehabilitation should occur in theclosed kinetic chain – nature of sport

Adequate AND safe function in the open chain is

critical = first step in rehabilitation



Exercise must be safe & challenging Stress multiple planes of motion

Incorporate a multisensory approach

Begin with static, bilateral & stable surfaces &

progress to dynamic, unilateral & unstable surfaces Progress towards sports specific exercises

Utilize open areas

Assistive devices should be in arms reach early on

Sets and repetitions 2-3 sets, 15 → 30 repetitions or

10 of the exercise for 15 → 30 seconds later on in the

program

Rules of Balance Training



Classification of Balance Exercises Static -

CoG is maintained over a fixed base of support, on astable surface

Semi-dynamic Person maintains CoG over a fixed base of support while

on a moving surface

Person transfers CoG over a fixed base of support toselected ranges and or directions within the LOS, while ona stable surface

Dynamic Maintenance of CoG within LOS over a moving base of

support while on a stable surface (involve steppingstrategy)

Functional Same as dynamic with inclusion of sports specific task



Phase I Non-ballistic types of drills

Static balance training Bilateral to unilateral on

both involved & uninvolvedsides

Utilize multiple surfaces tosafely challenge athlete &

maintaining motivation With & without

arms/counterbalance

Eyes open & closed

Alterations in varioussensory information

ATC can add perturbations

Incorporation of multiaxialdevices

Train reflex stabilization & postural orientation

Prentice, 2004,4th ed.



Phase II

Transition from static to dynamic

Running, jumping and cutting – activities thatrequire the athlete to repetitively lose and gainbalance in order to perform activity

Incorporate when sufficient healing hasoccurred

Semi-dynamic exercised should be introduced inthe transition

Involve displacement or perturbation of CoG

Bilateral, unilateral stances or weight transfersinvolved

Sit-stand exercises, focus on postural



Bilateral Stance Exercises

Prentice, 2004,

4th ed.



Unilateral Semi-dynamic exercises Emphasize

controlled hipflexion, smoothcontrolledmotion

Single legsquats, step ups(sagittal ortransverseplane)

Step-Up-And-Over activities

Introduction toTheraband kicks

Balance Beam

Balance Shoes

Prentice, 2004,4th ed.



Phase III

Dynamic & functional types of exercise Slow to fast, low to high force, controlled to uncontrolled

Dependent on sport athlete is involved in

Start with bilateral jumping drills – straight plane jumpingpatterns

Advance to diagonal jumping patterns Increase length and sequences of patterns

Progress to unilateral drills Pain & fatigue should not be much of a factor

Can also add a vertical component to the drills

Addition of implements Tubing, foam roll

Final step = functional activity with subconscious dynamiccontrol/balance

h



Phase IIIExercises

Prentice,2004, 4th ed.



References

Prentice, W.E. (2004). Rehabilitation Techniquesfor Sports Medicine and Athletic Training, 4th ed., McGraw-Hill

Houglum, P.A. (2005). Therapeutic Exercise forMusculoskeletal Injuries, 2nd ed., HumanKinetics.

Kisner, C. & Colby, L. (2002). TherapeuticExercise Foundations & Techniques, 4th ed., F.A.Davis.

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