Chapter 5 Human Movement Science

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Chapter 5Human Movement Science
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Objectives

• After this presentation, the participant will be
  able to
• Describe biomechanical terminology, planes of
  motion, axes, joint motions, muscle actions, and
  how they relate to the kinetic chain.
• Describe how forces act on the HMS and influence
  movement.
• Provide an overview of motor behavior.
• Describe the importance of sensory information as
  it relates to movement.

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Human Movement System Function

• The Human Movement System must
• Be aware of its relationship to its environments,
  both internal and external.
• Gather necessary information regarding them.
• Produce appropriate motor responses.
• This ensures optimum functioning of the HMS and
  optimum human movement.

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Biomechanics

• Applies principles of physics to understand how
  the human body moves.
• Terminology
• Important to understand basic anatomic
  terminology
• Allows for effective communication

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Anatomic Locations

• Superior refers to a position above a reference
  point
• Inferior refers to a position below a reference
  point
• Proximal refers to a position nearest the center
  of the body or point of reference
• Distal refers to a position farthest from the
  center of the body or point of reference
• Anterior refers to a position on the front or
  toward the front of the body

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Anatomic Locations

• Posterior refers to a position on the back or
  toward the back of the body
• Medial refers to a position relatively closer to
  the midline of the body
• Lateral refers to a position relatively farther
  away from the midline of the body or toward the
  outside of the body
• Contralateral refers to a position on the
  opposite side of the body
• Ipsilateral refers to a position on the same side
  of the body

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Planes, Axes, and Joint Motion

• Three imaginary planes are positioned through the
  body at right angles, intersecting at the center
  of mass of the body.
• Movement is said to occur more predominantly in a
  specific plane if it is actually along the plane
  or parallel to it.
• Movement in a plane occurs about an axis running
  perpendicular to that plane.
• Anatomic position, is reference position

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Planes, Axes and Joint Motion

• Sagittal plane bisects body into right and left
  sides, occurs around coronal axis, flexion
  extension (ex. Hip extension)
• Frontal plane bisects body into front and back
  halves, occurs around anterior-posterior axis,
  abduction adduction (ex. Shoulder abduction)
• Transverse plane bisects the body into upper and
  lower halves, occurs around vertical axis,
  internal external rotation (ex. spinal
  rotation)
• Use the book to study all joint motions.

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Planes, Axes and Motion

• Horizontal abduction- movement of a limb in
  transverse plane from an anterior to lateral
  position
• Horizontal adduction-movement of the arm or thigh
  in the transverse plane from a lateral position
  to an anterior position.

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Scapular Motion

• Scapular retraction- occurs when the shoulder
  blades come closer together.
• Scapular protraction-occurs when the shoulder
  blades move further away from each other.
• Scapular depression-occurs when the shoulder
  blades move downward, whereas
• Scapular elevation-occurs when the shoulder
  blades move upward toward the ears.

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Muscle Actions

• Muscles produce a variety of actions known as the
  muscle action spectrum to manipulate forces.
• Eccentric
• Lengthening of the muscle
• Force reduction
• Ex. Gluteus Maximus eccentrically flexes the hip
• Isometric
• No appreciable change in the muscle length
• Dynamically stabilize the body
• Ex. Gluteus Maximus isometrically stabilizes the
  hip
• Concentric
• Shortening of the muscle
• Force production
• Ex. Gluteus Maximus concentrically extends the
  hip

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Functional AnatomyMuscles

• The traditional perception of muscles is that
  they work concentrically and predominantly in one
  plane of motion.
• It is imperative to view muscles functioning in
  all planes of motion and through the entire
  muscle contraction spectrum (eccentrically,
  isometrically, and concentrically).

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Muscle Force

• Force is defined as the interaction between two
  entities or bodies that results in either the
  acceleration or deceleration of an object.
• When muscular force is generated, the resulting
  movement is rotation at the joint. The term for
  rotational force is called torque.
• The fitness professional must gain an
  understanding of the different kinetic chain
  components involved to efficiently produce force
  and movement.

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LengthTension Relationships

• The length at which a muscle can produce the
  greatest force
• There is an optimal muscle length at which the
  actin and myosin filaments in the sarcomere have
  the greatest degree of overlap.
• Lengthening a muscle beyond this optimal length
  and then stimulating it reduces the amount of
  actin and myosin overlap, reducing force
  production.
• Shortening a muscle too much and then stimulating
  it places the actin and myosin in a state of
  maximal overlap and allows for no further
  movement to occur between the filaments, reducing
  its force output.
• When a muscle is tight or shortened due to
  adhesions and alters the way normal movement
  occurs this is called an Altered Length Tension
  Relationship. Ex. Feet turn out and put the
  Gluteus Maximus in a position that generates less
  force.

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ForceVelocity Curve

• Refers to the ability of muscles to produce force
  with increasing velocity
• As the velocity of a concentric muscle
  contraction increases, its ability to produce
  force decreases.
• As the velocity of an eccentric muscle
  contraction increases, its ability to produce
  force increases.

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ForceCouple Relationships

• A forcecouple is synergistic action of muscles
  to produce movement around a joint.
• Common ForceCouples
• Internal and external obliques rotate the trunk.
• Upper trapezius and lower portion of the serratus
  anterior rotate the scapula upward.
• Gluteus maximus, quadriceps, gastrocnemius, and
  soleus produce hip, knee, and ankle extension.
• All muscles working together for the production
  of proper movement are said to be working in
  proper forcecouple relationships.

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Muscle Leverage and Arthrokinematics

• Amount of leverage the kinetic chain has for any
  given movement depends on the leverage of the
  muscles in relation to the resistance.
• The closer the weight is to the joint, the less
  torque it creates and the easier it is to lift.
• The farther away the weight is from the joint,
  the more torque it creates and the harder it is
  to lift.

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Muscle Synergies

• Muscles are recruited by the central nervous
  system (CNS) as groups or synergies.
• Over time and through proposed stages of
  learning, these synergies become more fluent and
  automated.
• Squat Quadriceps, hamstrings, gluteus maximus
• Shoulder Press Deltoid, rotator cuff, trapezius

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Proprioception

• The cumulative neural input from the sensory
  afferents to the central nervous system
• Uses information from mechanoreceptors (muscle,
  tendon, ligament, and joint receptors) to provide
  information about static, transitional, and
  dynamic position, movement, and sensation
  pertaining to muscle and joint force.
• A vital source of information that the nervous
  system uses to gather information about the
  environment to produce the most efficient
  movement.

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Sensorimotor Integration

• The ability of the nervous system to gather and
  interpret sensory information to anticipate,
  select, and execute the proper motor response
• There has to be a perceived reason to activate
  muscle tissue for the reduction or stabilization
  of forces imposed on the body, or for the
  production of force to overcome imposed forces on
  the body.
• Achieved through the task of collecting and then
  interpreting all incoming sensory information.

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Sensorimotor Integration

• Only as effective as the quality of incoming
  sensory information
• The skeletal system must be properly aligned to
  allow the muscles to be positioned at the right
  lengthtension relationships.
• This is known as structural efficiency.
• Proper structural alignment puts the body in the
  correct position to efficiently absorb,
  distribute, and produce forces.
• This is known as functional efficiency.
• Any deviation in the alignment of the kinetic
  chain causes altered sensory input that results
  in an altered motor response.

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Feedback

• The use of sensory information and sensorimotor
  integration to aid the kinetic chain in the
  development of permanent neural representations
  of motor patterns.
• Internal
• External

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Internal Feedback

• The information coming back to the central
  nervous system from all sensory receptors
  (proprioception).
• Also known as sensory feedback
• Incoming (afferent) feedback is by the central
  nervous system to monitor movements and their
  outcomes, provide information about the
  environment, and allow for any necessary
  adjustments to be made.
• When a client feels a change in their environment
  it is considered Internal Feedback.

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External Feedback

• Information provided by some external source such
  as a fitness professional, videotape, or a heart
  rate monitor.
• Also known as augmented feedback.
• Provides clients with an external source of
  information that allows them to associate how the
  achieved movement pattern was (good or bad)
  compared with what they are feeling.

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External Feedback

• Two major forms
• Knowledge of Results
• Used after the completion of a movement to inform
  clients about the outcome of their performance.
• Knowledge of Performance
• Provides information about the quality of the
  movement pattern.
• Clients must not become dependent on external
  feedback, especially from the fitness
  professional, as this may detract from their
  responsiveness to the internal sensory input.

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Summary

• Each system of the human movement system (HMS) is
  interdependent.
• The entire HMS must work together to gather
  information from internal and external
  environments to create and learn movements (motor
  behavior).
• The body uses proprioception, sensorimotor
  integration, and muscle synergies to create
  efficient movement (motor control).
• Repeated practice, as well as internal and
  external feedback, allows this efficient movement
  to be reproduced (motor learning).