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Chapter 5
Human Movement Science
Purpose
• To provide the fitness professional with a fundamental
overview of how the components of the human movement
system (HMS) work together to form, learn, and produce
movement.
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.
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 its environments
– Produce appropriate motor responses
• This ensures optimum functioning of the HMS and
optimum human movement.
Biomechanics
• Biomechanics: motions that the HMS produces and the
forces that act on it
• Terminology
– Important to understand basic anatomic terminology
– Allows for effective communication
Anatomic Locations
• Superior: a position above a reference point
• Inferior: a position below a reference point
• Proximal: a position nearest the center of the body
or point of reference
• Distal: a position farthest from the center of the
body or point of reference
• Anterior: a position on the front or toward the front
of the body
Anatomic Locations
• Posterior: a position on the back or toward the back
of the body
• Medial: a position relatively closer to the midline of
the body
• Lateral: a position relatively farther away from the
midline of the body or toward the outside of the body
• Contralateral: a position on the opposite side of the
body
• Ipsilateral: a position on the same side of the body
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.
Planes, Axes, and Joint Motion
• Sagittal plane: bisects body into
right and left sides, occurs
around coronal axis, flexion and
extension.
• Frontal plane: bisects body into
front and back halves, occurs
around anterior–posterior axis,
abduction and adduction
• Transverse plane: bisects the
body into upper and lower
halves, occurs around vertical
axis, internal and external
rotation
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
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.
Muscle Actions
• Muscles produce a variety of actions known as the muscle
action spectrum to manipulate forces.
– Eccentric
• Lengthening of the muscle
• Force reduction
– Isometric
• No appreciable change in the muscle length
• Dynamically stabilize the body
– Concentric
• Shortening of the muscle
• Force production
Functional Anatomy: Muscles
• 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).
Muscle Force
• Force is defined as the interaction between two entities or
bodies that results in either the acceleration or
deceleration of an object.
• The human movement system is designed to manipulate
variable forces from a multitude of directions to effectively
produce movement.
• The fitness professional must gain an understanding of the
different kinetic chain components involved to efficiently
produce force and movement.
Length–Tension 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.
Force–Velocity 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.
Force–Couple Relationships
• A force–couple is synergistic action
of muscles to produce movement
around a joint.
– Common force–couples
• 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.
– Muscles working together for the
production of proper movement are
said to be working in proper force–
couple relationships.
Muscle Leverage and Arthrokinematics
• Bones act as levers that are
moved by the force of the
muscles around an axis (or
joints).
• 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.
– The farther away the weight
is from the joint, the more
torque it creates.
Motor Behavior
• How the kinetic chain is able to create and learn
movements
• Consists of the study of motor control and motor learning
Motor Control
• The study of movement
– How the central nervous system integrates internal and
external sensory information with previous experiences to
produce a motor response
Muscle Synergies
• Muscles are recruited by the
central nervous system 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
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
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
• 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
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 length–tension
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.
Motor Learning
• The integration of motor control processes with practice
and experience that leads to a relatively permanent
change in the ability to produce skilled movements.
– Looks at how movements are learned and retained for
future use
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
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.
External Feedback
• Information provided by some external source such as a
fitness professional, videotape, or a heart rate monitor
– Also known as augmented feedback
• Used to supplement internal 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”
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.
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).