Muscular Analysis of Movement

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Muscular Analysis of Movement

• Chapter 14, pp.260-264
• Chapter 17

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Simple Joint System
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System Level Function

• Force torque production for joint mobility and
  stability through rotation and translation of
  bones (segments)
• Muscle Actions
• Muscle Coordination (Synergy)

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Related Terminology

• muscle action the development of tension
  (force) by a muscle
• functional muscle group a group of muscles that
  are capable of causing a specific joint action
  (e.g., wrist radial deviators)
• motive force (or torque) force causing the
  observed movement
• resistive force (or torque) force opposing the
  observed movement

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Types of Muscle Actions

• Concentric
• Eccentric
• Isometric

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Concentric

• Shortens to cause movement
• Rotational movement
• Mechanically
• Net Muscle (Motive) Torque gt Net Resistive Torque

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Eccentric

• Lengthens to resist, control, or slow down
  movement
• Rotational movement
• Mechanically
• Net Muscle (Resistive) Torque lt Net Motive Torque

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Isometric

• Stays the same so that bone will stay fixed
• No movement
• Mechanically
• Net Muscle Torque Other Torque
• Total Net Torque 0

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System Level Muscle Actions

• Resulting motion dependent on all torques acting
  about the joint (net torque)

Isometric?
Eccentric?
Conditions for concentric?
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Muscle Coordination Roles that Muscles Play

• Agonists
• Antagonists
• Stabilizers
• Neutralizers

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Agonist (Mover)

• The role played by a muscle acting to cause a
  movement
• Prime movers
• Assistant movers

• Force development during concentric action
• Relaxation during eccentric action

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Antagonist

• The role played by a muscle acting
• to control movement of a body segment against
  some other non-muscle force
• to slow or stop a movement
• Force development during eccentric action
• Check ballistic movements
• Relaxation during concentric action

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Stabilizer

• The role played by a muscle to stabilize (fixate)
  a body part against some other force
• rotary (joint) stabilizer
• linear (bone) stabilizer
• Isometric muscle action

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Neutralizer

• The role played by a muscle to eliminate an
  unwanted action produced by an agonist
• Scapular or pelvic stabilization
• Multijoint muscles
• Elevation of the humerus
• Muscle action varies

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To perform a muscular analysis

1. Break the skill into phases.
2. Determine the joint action?
3. Determine the motive force muscle or some other
   force?
4. Determine the resistive force muscle or some
   other force?

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To perform a muscular analysis (ID muscle actions
and responsible groups)

• Identify whether there are joints/bones that must
  be stabilized
• Identify
• the FMG(s) that is(are) developing force
• the type of muscle action of the FMG(s)
• the roles played by the FMG(s)
• Identify neutralization.

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Example 1 Biceps Curl
Up Phase Down Phase
Joint Action
Motive Force
Resistive Force
FMG Developing Force
Muscle Action
Flexion
Muscle
Weight/Gravity
Elbow Flexors
Concentric
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Example 1 Biceps Curl
Up Phase Down Phase
Joint Action
Motive Force
Resistive Force
FMG Developing Force
Muscle Action
Flexion
Extension
Weight/Gravity
Muscle
Muscle
Weight/Gravity
Elbow Flexors
Elbow Flexors
Concentric
Eccentric
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Example 1 Biceps Curl
Agonists
Flexors Extensors
Up Phase Down Phase
Joint Action
Motive Force
Resistive Force
FMG Developing Force
Muscle Action
Flexion
Extension
Weight/Gravity
Muscle
Muscle
Weight/Gravity
Elbow Flexors
Elbow Flexors
Concentric
Eccentric
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Example 1 Biceps Curl
Antagonists
Extensors Flexors
Up Phase Down Phase
Joint Action
Motive Force
Resistive Force
FMG Developing Force
Muscle Action
Flexion
Extension
Weight/Gravity
Muscle
Muscle
Weight/Gravity
Elbow Flexors
Elbow Flexors
Concentric
Eccentric
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Stabilization?

• Rotary stabilization
• Wrist flexors
• Linear stabilization

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Neutralization?

• To prevent scapular or pelvic movement when
  moving humerus or femur
• Shoulder girdle retractors
• Shoulder girdle elevators
• To prevent unwanted motion caused by multijoint
  muscles
• Shoulder extensors
• Forearm pronators

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Neutralization

• To prevent scapular movement during elevation of
  the humerus
• Other?
• Biceps brachii shoulder flexion, RU supination
• Brachialis none
• Brachioradialis RU motion
• Pronator teres RU pronation

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Summary

• Movement at a single joint is possible because of
  the complex coordination that occurs between
  numerous muscles.
• Therefore, all those muscles must have adequate
  strength to accomplish its task in a given
  movement.
• Injury to or lack of strength in any of those
  muscles can result in the inability to perform
  the movement.

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Summary

• A muscular analysis allows us to identify the
  muscles that contribute to a movement and how
  they contribute to the movement.
• We can then prepare conditioning rehabilitation
  programs that target utilized muscles
  appropriately.