1. Chapter 5 Human Movement Science

2. 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.

3. 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.

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

5. 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

6. 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

7. 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

8. 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.

9. 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.

10. 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.

11. 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*

12. 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).

13. 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.

14. 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.
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.*

15. 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.

16. 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.
All muscles working together for the production of proper movement are said to be working in proper force–couple relationships.

17. 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.

18. 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

19. 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.

20. 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.

21. 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.

22. 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

23. 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.*

24. 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.”

25. 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.

26. 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).