Download Chapter 5: Re-establishing Neuromuscular Control

Re-establishing
Neuromuscular Control
Why is it critical to the rehabilitation
process?
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Refocuses the athlete’s awareness of peripheral
sensation & guides them into more coordinated motor
strategies
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Required to:
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Protect joints from excessive strain
Provide prophylactic mechanism to recurrent injury
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Complements traditional components of rehabilitation
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We rely on sensory information from the periphery from
our visual, vestibular, & somatosensory systems.
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Primary role of articular structures
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Stabilize & guide body segments
Provide mechanical restraint to abnormal joint motion
Dynamic restraint system
Capsuloligamentous tissue & musculotendon receptor
sensory role
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Detect joint motion & position
Detect changes in muscle length
Implicated in regulating muscle stiffness prior to loading
Injury results in damage to microscopic nerves
associated with peripheral mechanoreceptors
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Disrupts sensory feedback
Alters reflexive joint stabilization & neuromuscular
coordination
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Four critical elements of neuromuscular control in
rehab
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Rehabilitation should address feedback systems
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Joint sensation (position, motion, force)
Dynamic stability
Preparatory & reactive muscle characteristics
Conscious & unconscious functional motor patterns
Preparatory (feed-forward)
Reactive (feed-back)
Muscle sense is divided into 4 sensory functions:
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Sensation of passive movement
Sensation of active movement
Sensation of position
Sensations of heaviness & resistance
What is neuromuscular control?
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Signal transmission through afferent sensory pathways
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Proprioception
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Kinesthesia
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Conscious & unconscious appreciation of joint position
Awareness of position & movement
Any postural, positional or kinetic info provided to the CNS by
sensory receptors in muscles, tendons or joints
Sensation of joint motion or acceleration
Sensation of ACTIVE movement (contracting muscle)
Neuromuscular control
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Efferent motor response to sensory information
Proprioception & kinesthesia
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Motor control mechanisms
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Feed-forward neuromuscular control
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Feed-back neuromuscular control
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Planning movements based on sensory information from past
experiences
Preparatory muscle activity
Operates on premise of initiating a motor response in
anticipation of a load or activity
Continuously regulates muscle activity through reflexive
pathways
Reactive muscle activity
Operates directly in response to a potentially destabilizing event,
using a normal reference point
Muscle stiffness
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Ratio in change of force to change in length
Stiffer muscles resist stretching = more effective restraint to joint
displacement
Modified by muscle activation
Activities for Inducing Adaptations
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Open & closed kinetic chain activities
Balance training
Eccentric & high repetition low load exercises
Reflex facilitation
Stretch-shortening
Biofeedback training
Controlled positions of vulnerability
Physiology of Mechanoreceptors
 Articular
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Specialized nerve endings that transduce mechanical
tissue deformation into frequency modulated neural
signals
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Mechanoreceptors
Increased tissue deformation results in increased afferent firing
rate or rise in quantity of mechanoreceptors activated
Types
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Pacinian corpuscles – (Type II) sensitive to high-frequency
vibration; compression sensitive
Ruffini endings – (Type I) sensitive to stretching of the joint
capsule
Golgi-Mazzoni corpuscles – (Type III) sensitive to joint
compression, not joint motion
Free nerve endings – (Type IV) stimulated by pain &
inflammation when a joint is placed in an end position
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Normally not active in normal joint movement
Articular Mechanoreceptors
 Quick
adapting (QA)
 Cease
discharging shortly after onset of stimulus
 Provide conscious & unconscious kinesthetic
sensation in response to joint
movement/acceleration
 Type II
 Slow
adapting (SA)
 Continue
to discharge as long as stimulus is
present
 Continuous feedback & proprioceptive information
relative to joint position
 Type I, III
Musculotendon Mechanoreceptors
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Muscle spindles – located in the muscle
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Responds to stretch of a muscle
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Detects length & rate of length changes
Its stimulation leads to a contraction
 Transmit information via afferent nerves
 Innervated by small motor fibers (gamma efferents)
 Project directly on motoneurons (monosynaptic reflexes)
 Stretch reflex
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Stimulation results in reflex contraction
Continued stimulation (gamma motor nerves) heighten stretch
sensitivity
Muscle activity mediation
Musculotendon Mechanoreceptors
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Golgi Tendon Organs (GTO) – located in
tendon & musculotendon junction
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Detects tension within a muscle & responds to both
the contraction & stretching of a muscle
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Regulate muscle activity & tension
Its stimulation results in muscle relaxation
GTO’s have opposite effect of muscle
spindles by producing a relaxation in the
muscle being loaded
Neural Pathways of Peripheral
Afferents
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Encoded signals - transmitted from peripheral receptors via afferent
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Brain Stem = Balance
pathways (interneurons) to CNS
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Primary proprioceptive correlation center
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Cerebral Cortex – location of conscious movement
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Monosynaptic reflex pathway - links muscle spindles directly to
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Balance
motor nerves
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Influenced by peripheral afferent mechanism mediating joint proprioception
Partially dependent on inherent ability to integrate joint position sense,
vision & vestibular apparatus with neuromuscular control
Re-establishing Neuromuscular
Control
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Injuries result in decreases in neuromuscular
control
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Pathoetiology
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Injury results in deafferentation of ligament & capsular
mechanoreceptors
Joint inflammation & pain compound sensory deficits
Congenital/pathological joint laxity have diminished
ability to detect joint motion & position
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Proprioceptive, kinesthetic deficits & mechanical instability lead
to functional instability
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Objectives for Neuromuscular Rehabilitation
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Develop/re-establish afferent & efferent characteristics that
enhance dynamic stability
Elements
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Proprioceptive & kinesthetic sensation
Dynamic joint stabilization
Reactive neuromuscular control
Functional motor patterns
Afferent & Efferent Characteristics
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Sensitivity of peripheral receptors
Facilitation of afferent pathways
Muscle stiffness
Onset rate & magnitude of muscle activity
Simultaneous activation of agonist/antagonist
Reflexive & discriminatory muscle activation
Neuromuscular Characteristics
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Peripheral Afferent Receptors
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Altered peripheral afferent information may disrupt motor control &
functional stability
Repetitious athletic activity enhances proprioceptive & kinesthetic
acuity = facilitated afferent pathways
Enhanced joint motion awareness improves feed-forward &
feedback mechanisms
Muscle Stiffness
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Significant role in preparatory & reactive dynamic restraints
Exercises that encourage muscle stiffness should be incorporated
into rehabilitation programs
Eccentric exercises
 Chronic overload results in connective tissue proliferation, desensitizing
GTO’s & increase muscle spindle activity
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Power trained vs. Endurance trained athletes
Power athlete = Faster muscle pre-activation (EMG)
 Endurance athlete = Increased baseline motor tone
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Reflexive Muscle Activation
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Reflex latency times may be dependent on types of
training (endurance vs. power)
Preparatory & reactive muscle activation might
improve dynamic stability & function if muscle
stiffness is enhanced in deficient joints
Decreasing electromechanical delay between joint
loading & protective muscle activation can increase
stability & function
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Discriminate
Muscle Activation
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Unconscious control of
muscle activity is
critical in balance &
coordination
May initially require
conscious activation
prior to unconscious
control
Use of biofeedback
can aid in this process
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Help eliminate
imbalances & reestablish preparatory &
reactive muscle activity
Elements for Neuromuscular Control
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Proprioception & Kinesthesia Training
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Restore neurosensory properties
Enhance sensitivity of uninvolved peripheral afferents
Joint compression is believed to maximally stimulate
articular receptors
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Early repositioning tasks are critical
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Closed chain exercises through available ROM
Conscious to unconscious joint awareness
Applying neoprene sleeve or ace wrap stimulates
cutaneous receptors – additional proprioception &
kinesthesia
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Dynamic Stabilization
Encourage preparatory agonist/antagonist
coactivation
 Restores force couples & balances joint forces
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Activities that require anticipatory & reactive
adjustments to imposed loads
Combination of balance & stretch shortening
exercises
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Results in decreased loads on static structures
Encourages preparatory & reactive muscle activity
Closed chain exercises induce coactivation &
compression
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Reactive Neuromuscular Control
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Stimulates reflex pathways
Object is to impose perturbations that stimulate reflex
stabilization
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Can result in decreased response time & develop reactive
strategies to unexpected joint loads
Perturbations should be unexpected in order to facilitate
reflexive activity
Functional Activities
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Objective is to return athlete to pre-injury activity
Involves sports specific movement patterns designed
to restore functional ability
Can be utilized to assess readiness for return to play
Stresses peripheral afferents, simultaneous muscle
activation, reflexive activity
Progress from conscious to unconscious
Develop functionally specific movement patterns,
ultimately decreasing risk of injury
Lower Extremity
Techniques
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Techniques should focus on muscle
groups that require attention
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Use of closed-chain activities is
encouraged
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Progress from no weight to weight assisted
Replicates environmental demands
Plays on principles of neuromuscular
control
Joint stabilization exercises
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Balance & partial weight bearing activities
Progress non-weight bearing to full weightbearing
Balance on unstable surfaces can begin
once full-weight bearing
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Slide board exercises
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Stair climbing (forward & backward)
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Emphasis on eccentric strength
Biofeedback
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Stimulates coactivation with increasing muscle force &
endurance
Stimulating dynamic stability & stiffness
Used to develop agonist/antagonist coactivation
Encourages voluntary muscle activation
Stretch-shortening exercises
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Eccentric deceleration & explosive concentric contractions
Incorporate early in process (modified loads)
Involves preparatory & reactive muscle activity
Hopping progression
Double  Single leg
 Sagittal  Lateral  Rotational hopping
 Surface modification
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Rhythmic stabilization
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React to joint perturbations
preparatory & reactive
muscle activity
 Alterations in loads &
displacement
Hopping & landing (double
support, single support,
rotation)
 Challenge athlete
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Trampoline Hopping
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Hopping & catching
 Hopping & landing on varying
surfaces
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Unstable surfaces
Linear & angular
perturbations, altering center
of gravity
 Facilitate reflexive activity
 Ball toss
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Functional activities
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Restore normal gait
Athlete must internalize
normal kinematics (swing &
stance)
 Utilize retro walking
(hamstring activity), pool or
unloading devices
 Cross over walking, figure 8’s,
cutting, carioca, changes in
speed
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Disrupt concentration, induce
unconscious response &
reactive adaptation
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Functional activities that
simulate demands of sport
Upper Extremity Techniques
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Work to maintain joint congruency & functional
stability
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Requires dynamic restraint via coordinated muscle
activation
Injury to static stabilizers
 Failure of dynamic restraint system
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Could result in repetitive loads, compromising joint
integrity & predisposing athlete to re-injury
Adapt lower extremity exercise for upper
extremity
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Muscle stiffness
Enhance using elastic resistance (focus on eccentrics)
 High repetitions & low resistance
 Upper extremity ergometers should be incorporated
for endurance
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Dynamic stabilization
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Stability platforms
Push-ups, horizontal abduction, tracing circles on slide
board with dominant & non-dominant arms
Plyometric exercise
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Reactive Neuromuscular
Exercises
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Manual perturbations
Rhythmic stabilization with
gradual progression
Placing joint in inherently
unstable positions
Functional Training
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Developing motor patterns
in overhead position
Reproduce demands of
activity
Emphasis on technique
Re-education of functional
patterns
Speed & complexity in
movement require rapid
integration of sensory
information