Uploaded: 7 years ago
Contributor: Guest
Category: Kinesiology
Type: Outline
Tags: force, class, motion, lever, muscular,
define, gravity, forces, distance, three,
describe, equilibrium, muscle, speed, contraction, object, tissue, action, movement, joint, chapter, friction, increases, mechanics, describe, reaction, students, greater,
Rating:
N/A
|
Filename: 0135077893_ch06.doc
(82.5 kB)
Page Count: 5
Credit Cost: 1
Views: 204
Last Download: N/A
|
Description
Chapter 6 Notes
Transcript
Therapeutic Kinesiology Instructor Manual: Ch06 p.1
TK INSTRUCTOR MANUAL: CHAPTER 6
Biomechanics
Chapter manuals include:
Objectives
Lecture Notes
Suggested Classroom and Student Development Activities
For other chapter-by-chapter resources, see:
Key Term Quizzes
Muscle Origin and Insertion Worksheets
Muscle OIAs List by Chapter
MyTest Test Bank
For additional resources see “Teaching Tips and Tools”:
7 research-based learning principles for kinesiology courses in massage
5-step self-directed learning cycle for body mechanics courses
Tools that build metacognitive skills: e.g., concept (mind) maps, grading rubrics, and self-assessments inventories
OBJECTIVES
Define velocity, acceleration, and deceleration. Explain how gravity affects velocity during muscular contractions.
Define friction. Describe what increases and decreases friction.
Define line of pull. Define the mechanical axis of a bone.
Define a reverse muscle action and describe how a joint movement can reverse.
List and define each of Newton’s three laws of motion.
Describe a force vector in relation to a muscular contraction.
List and describe three types of forces that produce movement.
Define torque and describe how muscles work as force couples to produce torque.
Describe the forcevelocity relationship.
Describe the stressstrain curve and its relationship to tissue response under load.
Define a lever and its three parts. Identify the output favored by each lever.
Describe each type of the three levers and provide an example of each one.
Define equilibrium and contrast the three different types of equilibrium.
Describe several applications of biomechanics to effective and sound body mechanics.
LECTURE NOTES
BIOMECHANICS: STUDY OF MECHANICAL ASPECTS OF HUMAN MOVEMENT
Concepts
Statics: nonmoving systems (e.g., posture)
Dynamics: moving systems (e.g., sports activities)
Three main body masses: head, thorax, pelvis
Line of gravity (LOG): vertical axis
Center of gravity (COG): center of weight
Effects of gravity on velocity
Velocity: Combination of speed and direction
Acceleration: Increases velocity
Occurs during motion in direction of gravity
Eccentric contractions
Examples: walking downhill, lowering weights
Deceleration: Decrease in velocity
Occurs during motion against gravity
Concentric contractions
Examples: walking uphill, lifting weights
Friction: A force between moving surfaces
Too much friction prevents motion
Too little friction prevents control and stability
Line of pull
Direction of muscular force on joint
Changes as angle of joint moves
Stabilizing effect when vertical
Mobilizing effect when perpendicular
Mechanical axis of a bone
Imaginary line between center of articulating joints
Depends on overall shape of bone
Reverse muscle action
Moving and fixed ends of muscle switch roles
Also reverses the joint action
Any muscle action can be reversed
THREE LAWS OF MOTION
Inertia: Body at rest or in linear motion tends to stay at rest
or in motion unless acted upon by an external force.
Inertia: A property of mass that
Resists the initiation of motion
Resists changes in motion
Acceleration: The distance an object travels when set in motion
is proportional to the force causing the movement.
Greater force + stronger acceleration = farther the object travels
Power: Strength plus velocity
Momentum: Force applied to increase velocity
Action and reaction: For every action there is an
opposite and equal reaction.
The greater a force, the greater its counterforce
Ground reaction force (GRF): Resistance from ground
FORCE
Force vector: Size and direction of force
Muscular force measured by
Point of application: muscular attachment site
Direction of force: line of muscular pull
Magnitude of force: strength of contraction
Types of force
Linear
Forces applied along same axis
Either toward or away from each other
Can result in gliding motion
Can result in rotary motion (e.g., joint flexion)
Parallel
Separate, linear forces of equal magnitude
Forces applied in same plane
Force in either same or opposite directions
Concurrent
Two forces with same point of application from different directions
Creates a third resultant force
Torque
Rotational motion around an axis
Rotary counterpart of linear force
Moment arm
Perpendicular distance between line of pull/axis of motion
Greatest at 90 degrees
Force couple
Two parallel forces in opposite directions (e.g., two hands turning a wheel)
Force couples produce motion (e.g., muscles producing posterior pelvic tilt)
Forcevelocity relationship
Speed of contraction affects force it generates
As muscular force increases, speed of contraction decreases (e.g., switching gears on a bike)
As muscular force decreases, speed of contraction increases (e.g., slowing down touch to apply deeper pressure)
Stressstrain relationship
Stress: Internal resistance of tissue to deformation
Strain: Change in tissue length due to deformation
Stressstrain curve of a tissue: Determined by comparing length of tissue
after being under stress to its original length
LEVERS
Simple machine that magnifies force and converts force to torque
Every lever has three parts
Axis (A): Fulcrum around which lever pivots
Effort (E): Force that moves lever
Resistance (R): Load or weight that lever moves
Lever arms
Effort arm (EA): Distance between effort and axis
Resistance arm (RA): Distance between resistance and axis
Types of levers depend on arrangement of parts
First-class lever: Favors force over distance
Second-class: Produces power, load in middle
Third-class: Favors distance over force
Levers in human body: Each body segment functions as lever arm
Axis: Joints serve as fulcrums
Resistance: Body's weight or external object are load
Effort: Muscle contraction produces force
Mechanical advantage of a lever (M Ad): Ratio between EA and RA
First class: RA = EA
Can also be EA > RA or RA > EA
Only lever that can balance force and distance
Examples: crowbar, teeter-totter
Second class: EA > RA
Favors force over speed and distance
Example: wheelbarrow
Third class: RA > EA
Favors speed and distance over force
Examples: brooms, bats
Equilibrium
Stable equilibrium
All forces balance each other
All forces add up to zero
Unstable equilibrium
Minimal force causes COG to shift
Example: person balancing on physioball
Neutral equilibrium (Figure 6.27c)
COG remains level as object shifts position
Example: rolling ball
Maintaining equilibrium
Important for safe body mechanics
Keep COG over base of support (BOS)
Keep COG close to line of gravity (LOG)
When lifting
Keep spine straight
Contract abdominals
Lower COG for greater stability by bending knees and hips
Push down to come up
SUGGESTED CLASSROOM AND STUDENT DEVELOPMENT ACTIVITIES
PROVIDE AN OVERVIEW OF CLASS
Before class, write a short, schematic overview of the class on the board, then go over it at the beginning of class. For example:
Today's class covers:
General terms and concepts
Three laws of motion
Force
Levers
Activities: Review, lecture, biomechanics lab, recap, and homework
GOING OVER GUIDELINES EXERCISE
Balancing stability with mobility (p. 148)
EXPLORING TECHNIQUE EXERCISE
Stress and strain in myofascial release (p. 142)
PRACTICAL APPLICATIONS
Have students analyze one activity of daily living, a natural movement that involves the manipulation of some implement (broom, towel, sponge, handle, etc.) and analyze it for use of levers.
Have students analyze body use patterns in several types of massage strokes for ways to improve leverage.
SELF-CARE EXERCISES
Integrate the self-care exercises in this chapter into the lecture. This will help students make connections of abstract biomechanical principles with pattern recognition skills and practical applications to their own body mechanics.
Balancing your body with reverse actions (p. 133)
Overcoming on-the-job inertia (p. 134)
Exercises for grounding and countersupport (p. 136)
Efficient use of force in pressure applications (p. 139)
Pushing and pulling with a partner (p. 146)
Lifting a heavy object (p. 148)
© 2013 by Education, Inc. Foster, Instructor Resources for Therapeutic Kinesiology
|
|