Download Basic-B¡omechanical-Factors-and

3-1
Kinesiology for Manual Therapies
Chapter 3
Basic Biomechanical Factors and Concepts
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-2
Learning Outcomes
o
o
McGraw-Hill
3-1 Differentiate between the levers
and explain how they apply to
physical performance.
3-2 Discuss how the
musculoskeletal system functions as
a series of simple machines.
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-3
Learning Outcomes


McGraw-Hill
3-3 Describe how knowledge of
torque and lever arm lengths can
help improve physical performance.
3-4 Recall Newton’s laws of motion
and cite examples of how the laws
can apply to improving physical
performance.
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-4
Learning Outcomes



McGraw-Hill
3-5 Compare balance, equilbrium,
and stability and discuss how they
can each help improve physical
performance.
3-6 Define force and momentum
and describe how they can help
improve physical performance.
3-7 Analyze the basic effects of
mechanical loading on the tissues of
the body.
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-5
Introduction
Motion
cannot occur unless there is force
behind it.
Motion includes many levers, torque, and
pulleys that all exist as force is applied.
The study of physical action of forces is
called mechanics.
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-6
Introduction (cont.)
The
study of mechanics as it relates to
the functional and anatomical analysis of
biological systems is known as
biomechanics.
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-7
Introduction (cont.)
Kinematics is concerned with the
description of motion.
 Kinetics is the study of forces associated
with the motion of the body.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-8
Types of Machines Found in the
Body
Mechanical advantage – the ability to
apply a relatively small force to move a
greater resistance.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-9
Types of Machines Found in the
Body (cont.)
Machines function in four ways:
 To balance multiple forces
To enhance force
To enhance range of motion
To alter the resulting direction of the
applied force
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-10
Types of Machines Found in the
Body (cont.)
Three machines in the body produce
movement:
Levers, wheels and axles, and pulleys
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-11
Levers
A lever is defined as a rigid bar that
turns around an axis of rotation.
 An axis is the point of rotation around
which the lever moves.
 The lever rotates around the axis as a
result of the force.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-12
Levers (cont.)
Bones are the lever bars, the joints are
the axes, and the muscles produce the
force.
 First-class lever
 Second-class lever
 Third-class lever

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-13
Levers (cont.)
First-class lever is designed for balance
movements.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-14
Levers (cont.)
Second-class lever is designed to
produce force movements.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-15
Levers (cont.)
Third-class levers are designed to
produce speed and range-of-motion
movements.
 The force is applied between the axis
and the resistance.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-16
Levers (cont.)
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-17
Levers (cont.)
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-18
Factors in the Use of Anatomical
Levers
Torque – moment of force
 Eccentric force
 Force arm
 Resistance arm

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-19
Factors in the Use of Anatomical
Levers (cont.)
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-20
Factors in the Use of Anatomical
Levers (cont.)
Human levers are built for speed and
range of motion at the expense of force.
 The longer the lever, the more effective
it is in imparting velocity.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-21
Factors in the Use of Anatomical
Levers (cont.)
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-22
Factors in the Use of Anatomical
Levers (cont.)
Wheels and axles are used to enhance
range of motion and speed of movement in
the musculoskeletal system.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-23
Factors in the Use of Anatomical
Levers (cont.)
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-24
Factors in the Use of Anatomical
Levers (cont.)
The lateral malleolus acts as a pulley
around which the tendon of the peroneus
longus runs. The pulley directs the force to
the plantar aspect of the foot.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-25
Factors in the Use of Anatomical
Levers (cont.)
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-26
Laws of Motion and Physical
Activities
Linear motion – motion along a line
 Angular motion – rotation around an
axis
 Displacement – change in the position
or location of an object from its original
point of reference

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-27
Laws of Motion and Physical
Activities (cont.)
Distance – sum length of measurement
traveled
 Speed – how fast an object is moving
 Velocity – direction and describes rate
of displacement

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-28
Laws of Motion and Physical
Activities (cont.)
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-29
Laws of Motion and Physical
Activities (cont.)
Inertia – resistance to action or change
 Law of inertia – a body in motion tends
to remain in motion at the same speed in a
straight line unless acted on by a force; a
body at rest tends to remain at rest unless
acted on by a force.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-30
Laws of Motion and Physical
Activities (cont.)
Acceleration – rate of change in
velocity
 Mass – amount of matter

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-31
Laws of Motion and Physical
Activities (cont.)
Law of acceleration - A change in the
acceleration of a body occurs in the same
direction as the force that caused it. The
change in acceleration is directly
proportional to the force causing it and
inversely proportional to the mass of the
body.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-32
Laws of Motion and Physical
Activities (cont.)
Law of reaction - For every action there
is an opposite and equal reaction.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-33
Laws of Motion and Physical
Activities (cont.)
Sherrington’s law – is the law of
reciprocal innervation. For every neural
activation of a muscle, there is a
corresponding inhibition of the opposing
muscle.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-34
Friction
Friction is the force that results from the
resistance between the surfaces of two
objects moving against one another.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-35
Balance, Equilibrium, and Stability
Balance is the ability to control
equilibrium.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-36
Balance, Equilibrium, and Stability
(cont.)
Factors enhancing equilibrium, stability,
and balance include:
 Center of gravity falls within the base of
support.
 Size of the base.
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-37
Balance, Equilibrium, and Stability
(cont.)
Balances depends on weight or mass.
 Balance depends on the height of the
center of gravity.
 Balance depends on where the center of
gravity is in relation to the base.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-38
Balance, Equilibrium, and Stability
(cont.)
Stability is increased by enlarging the
size of the base.
 Equilibrium can be enhanced by
increasing friction.
 Rotation around an axis aids balance.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-39
Balance, Equilibrium, and Stability
(cont.)
Kinesthetic physiologic functions
contribute to balance.
 Principles of balance, stability, and
center of gravity can be applied to sports,
preventing injuries, and achieving good
body mechanics for the manual therapist.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-40
Force
Force is the product of mass times
acceleration.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-41
Mechanical-Loading Basics
Only muscles can actively generate
internal force, but tension in tendons,
connective tissues, ligaments, and joint
capsules may generate passive internal
forces.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-42
Mechanical-Loading Basics (cont.)
External force are produced outside the
body from gravity, inertia, or direct
contact.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-43
Mechanical-Loading Basics (cont.)
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-44
Functional Application of Throwing
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-45
Functional Application of Throwing
(cont.)
Newton’s laws of motion apply in
throwing:
 Law of inertia
 Law of acceleration
 Law of reaction
McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-46
Functional Application of Throwing
(cont.)
Leverage factor
 Balance, equilibrium, stability

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-47
Chapter Summary
Types of machines found in the body,
levers, and factors in the use of anatomical
levers provides a foundation for
understanding how movement occurs from
a mechanical perspective.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-48
Chapter Summary (cont.)
The laws of motion and physical
activities give fundamental explanations
for movement.
 Friction, balance, equilibrium and
stability, force, and mechanical-loading
basics are included in the topic of how the
body moves.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-49
Chapter Summary (cont.)
The example of throwing utilizes the
laws of motion, leverage, and balance to
perform the sport.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-50
Chapter Review
The Chapter Review is divided into true
and false, short answers, and multiple
choice questions.
 The questions are designed for the
students to test their knowledge.

McGraw-Hill
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved
3-51
Explore and Practice

McGraw-Hill
Students should utilize the questions and
charts at the end of the chapter to help
focus on the content of the chapter.
© 2011 by The McGraw-Hill Companies, Inc. All rights reserved