Kinesiology

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Kinesiology

• Andrew L. McDonough, PT, EdD
• Dominican College
• Physical Therapy Program

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Kinesiology

• Functional anatomy (traditional)
• Biomechanics
• Statics
• Dynamics
• Kinematics (geometry of motion)
• Kinetics (forces that account for motion)

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Voluntary Movement Factors Levels of Analysis

• (Macro)physiologic
• Biomechanics
• Motor control
• Motor learning

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Types of Motion

• Translatory
• A
  B
• Rotary constant radius
• Curvilinear radius varies

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Basic Components of aJoint System

• Muscle attachments (proximal distal)
• Axis of rotation
• Fixed center
• Instant center
• Innervation

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Terms

• Agonist Antagonist (context-dependent)
• Synergist (3 definitions)
• Primary vs. Secondary (Tertiary) movers
• Fixators/stabilizers Immobilizers

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Muscle Factors

• Physiological cross-section
• Geometry of muscle/tendon

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Physiological Cross-Section
Less force
More force
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Geometry

• Type types
• Fusiform (cigar-shaped)
• Penniform (feather-shaped)
• Bi-pennate
• Uni-pennate
• Multi-pennate

Bi-
Uni-
Multi-
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Significance of Geometry

• Fusiform
• Parallel arrangement of fibers (all have same
  proximal and distal attachments)
• Virtually ALL (less 10) of force delivered to
  attachments
• Have large force (torque) generating potential
• Muscles/fibers to be impulsive but not endurant

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Significance of Geometry

• Penniform
• Implies an angle-of-insertion
• Gross muscle level
• Muscle fiber level

.
angle-of-insertion
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Angle-of-insertion
resultant force
X
.
angle-of-insertion
axis
rotary component (Y) force
.
900
(joint) compressive component (X)
T f x d
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Muscle Contraction Types

• Isometric
• Isotonic
• Concentric (shortening contraction)
• Eccentric (lengthening contraction)
• Isokinetic (?)

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Muscle ContractionLevels of Analysis

• Sarcomere (microanatomical)
• Gross muscle

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Isometric Contraction

• Sarcomere shortens delivering force to tendon
• Gross length remains constant

Demo
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Concentric Contraction

• Sarcomere shortens
• Gross muscle shortens pulling on bony attachments
• If the muscle crosses a joint the joints moves
  through a ROM via torque created

Demo
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Eccentric Contraction

• A lengthening reaction
• Occurs in a muscle that has already undergone a
  concentric contraction
• External force applied exceeds internal muscular
  force being generated
• Muscle lengthens under neuro-motor control

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Sources of Tension

• Muscle (contractile element)
• Tendon (non-contractile element CT)

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Premise Concentric vs. Eccentric Contractions

• Per comparable volumes of muscle tissue, more
  tension will always be realized during eccentric
  contractions.

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Analysis

• Concentric contraction
• Source of tension
• Contractile elements (muscle)
• Eccentric contraction
• Source of tension
• Contractile elements (muscle)
• Non-contractile elements (CT tendon)
• The tendon is in a pre-loaded condition due to
  previous concentric contraction

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EMG Activity

• Ratio 0.5 1.0 (eccentric concentric)
• Tension realized is the sum-total of contractile
  non-contractile elements
• Muscle working eccentrically will not have to
  work as hard since some the total tension is
  provided by the pre-loaded tendon

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Metabolic Activity

• Consequently if the muscle is not working as hard
  under eccentric control less energy is required
  to sustain a contraction by a factor of 10 30
• Less lactic acid is produced eccentrically

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Muscle Contraction Fiber Types

• Concentric Type I and IIa motor units most
  active
• Eccentric Type IIb motor units most active

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Relationship Between a Muscle (or Muscle Fiber)
Tension Production

• Blix experiments

probe
dynamometer
frog soleus muscle fiber
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Muscle Lengthened Passively

• Tension production will soon become linear and
  muscle fiber will react elastically

Passive Tension Curve
Tension
Length
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Muscle Stimulated at VariousPre-set Lengths
Shortening Lengthening
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Blix Curve or Length-tension
Curve
Tension
0
100
Rest length
Length
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Length-Tension Relationship

• During active contraction a muscle (or muscle
  fiber) will generate maximal tension at or
  slightly greater than rest length.
• Levels of analysis
• Gross muscle
• Muscle fiber/sarcomere

Demo
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Motor Control System

• Constantly evaluates tension via length
  assessment (GTOs spindles)
• Often optimizes tension via maintaining muscle
  length
• Usually goes out of its way to maintain length

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Question

• What happens when a muscle is called upon to do
  the job it is intended to do (i.e., shorten)?

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Muscle Types

• One-joint
• Two (two-or-more)-joint

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Active Insufficiency

• Two-joint muscle shortens simultaneously over
  both joints
• Rapidly loses length (shifts left on the
  length-tension curve)
• Force and torque production decrease quickly

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Two-Joint MusclesGeneral Rule

• In a motor control context, two-muscles rarely
  contract over both (all) joints simultaneously
• While one end of the muscle is shortening over
  its associated joint
• The other end is being lengthened over its
  associated joint
• The net effect preserve length and therefore
  force and torque
• Motor control system avoids active insufficiency
  in most cases

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Passive Insufficiency

• Muscle passively elongated over both (all) joint
  simultaneously
• At some point the muscle reaches its elastic
  limit
• ROM will be limited across both joints

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Velocity Tension Relationship
Concentric
Eccentric
Inverse Relationship
Tension
-

0
100
Demo
Velocity
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Other Terms

• Strength ability to generate tension
• Power rate of doing work (Tf x d)
• Low power
• High power
• Endurance ability to sustain the work being
  preformed

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Other Terms

• Arthrokinematics study of the relationship
  between (among) articulating bony surfaces
• Joint play
• Congruency
• Component motion
• Overall motion

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