Lesson 13.1 APPLIEDBIOMECHANICSedhswilson.weebly.com/uploads/5/6/1/3/5613731/chapter_13.pdf · Human Movement Analysis ... Biomechanical concepts and principles provide a basis for

Lesson 13.1

© 2015 Thompson Educational Publishing, Inc. 1

APPLIED BIOMECHANICS

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TOPICS COVERED IN THIS LESSON

• (a) Reviewing Biomechanical Principles

• (b) Functional Movement and Movement Efficiency

Focussing Question


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“What are some purposes for thebiomechanical analysis of

functional movement?”

Human Movement Analysis


Biomechanical concepts and principles provide abasis for human movement analysis. The goals of movement assessment vary depending on the desired outcome; some goals include:

• To fine-tune an athlete’s movement techniques to reduce the risk of injury or to improve

performance;

• To modify a worker’s movement patterns to delay

the onset of fatigue on the job; or

• To provide feedback about a person’s progress in

regaining movement proficiency while undergoing rehabilitation.

Review of Biomechanical Principle 1


Maintaining and controlling our balance is animportant aspect of movement proficiency.

• How stable or balanced an individual is depends

on four factors, as stated in biomechanical principle 1.

• Principle 1: The greater the mass, the lower the

centre of mass to the base of support, the larger the base of support, and the closer the centre

of mass is positioned to the base of support, the

more stability increases.

Review of Biomechanical Principles 2 & 3


In many activities, we must exert maximum effort in order to accomplish a specifictask. Exerting maximum effort involves biomechanical principles 2 and 3:

• Principle 2: The production of maximum force requires the use of all possible joint movements

that contribute to the task’s objective.

• Principle 3: The production of maximum velocity

requires the use of joints in order—from largest

to smallest.



Biomechanical principles 4 and 5 are related tolinear motion—motion that takes place whena body or its collective parts move the samedistance, in the same direction, in the sameamount of time.

• Principle 4: The greater the applied impulse, the

greater the increase in velocity. For example, by applying a large impulse, a hitter in cricket, tennis,

and baseball can strike the ball so that it leaves the

bat with greater velocity.

• Principle 5: Movement usually occurs in the

direction opposite that of the applied force. For

example, in making a cut, a soccer player will push his or her foot against the ground to make a

change in direction away from an opponent.



Biomechanical principles 6 and 7 are related torotational motion. Also called angular motion,rotational motion is movement around an axis. Our bodies have many such axes—they are called joints. Joints serve as axes of rotation for the movement of our limbs. The human body as a whole can also rotate freely about one (or more) of the three anatomical axes.

• Principle 6: Angular motion is produced by the

application of a force acting at some distancefrom an axis; that is, by torque.

• Principle 7: Angular momentum is constant when

an individual or object is free in the air.

The Law of Conservationof Angular Momentum


When rotations are introduced, a trampolinistwho is high in the air has generated angular momentum: the product of the rate at which theathlete is rotating, known as angular velocity, and the extent to which the athlete’s body resists angular motion. Resistance to angular motion is known as the moment of inertia.

• The law of conservation of angular momentum states that the total angular momentum of a

rotating body remains constant if the net torque

acting on it is zero.

Assessing Functional Movement


Functional movement is movement that is a product of the world we live in.

• Such movement places demands on our core

musculature and nervous system.

• Functional movement also usually involves multi-

directional and multi-joint movements.

• Biomechanists and other movement professionals

assess functional movement in order to improve

not only a person’s movement proficiency, or

competence, but also their movement efficiency.

Efficiency of Movement


An efficient movement is one that uses the least amount of energy to complete a task.

• The tasks that humans perform vary widely, from

walking, to competing in a sport, to working on anassembly line, and so on.

• Inefficient movements can lead to errors in

performance, fatigue, injury, or even death.

• Moving efficiently helps people sustain their

energy output for as long as possible.

• Wasted energy (known as an energy leak) leads to fatigue more quickly.

Maximizing Efficiency Through Practice


Disruptions in Movement Patterns


Movement professionals often use informationgained from movement analyses to counteract situations that disrupt the proficiency and efficiency of human movement.

• For example, rapid growth during adolescence can shift the location of a young person’s centre

of mass, which can temporarily affect balance,

coordination, and performance.

• Disrupted movement patterns can also arise from

congenital conditions such as fibular hemimelia, or

the absence of fibulas in the lower limbs.

• Injuries such as a sprained ankle can also disrupt

well-established, efficient movement patterns.

Overcoming Disrupted Movement Patterns


Methods of Movement Analysis


Biomechanists, physiotherapists, rehabilitation specialists, coaches, and other movement professionals spend a great deal of time assessing functional movement in a widevariety of contexts.

• They rely on two major methods of

analysis: qualitative (non-numerical)analysis, or quantitative (numerical)

analysis.

• Sometimes, however, analyses of human movement depend on a combination of both

qualitative and quantitative assessment methods.

Revisiting the Question


~ ~ ~

“What are some purposes for thebiomechanical analysis of

functional movement?”

Lesson 13.1


SUMMARY

Analysis of human functional movement based on an understanding of biomechanical conceptsand principles serves many purposes.

• The goals of movement analysis vary depending

on the outcome.

• Functional movement assessment strives to

improve a person’s movement proficiency, or

competence, as well as their movement efficiency.

• Biomechanists and other movement professionals

use qualitative analysis, quantitative analysis, or

a combination of both to counteract disruptions in

the proficiency and efficiency of human movement.

Lesson 13.2


QUALITATIVE AND QUANTITATIVE ANALYSIS

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• (a) Qualitative Analysis of Human Movement

• (b) Quantitative Analysis of Human Movement

Focussing Question


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“How does qualitative analysis compare with quantitative analysis in terms of

purpose and methods?”

Qualitative Analysis of Human Movement


Qualitative analysis of human movement involves describing and analyzing movements primarily by using non-numerical methods.

• Qualitative analysis essentially involves observing

and critiquing human movements as patterns and

sequences.

• It ranges from a sensory observation of a

movement or task to a comprehensive, structured

approach involving preparation, observation,diagnosis-evaluation, and intervention.

• The simplest type of qualitative analysis features

verbal feedback, whether spoken or written.

Purposes of Qualitative Analysis


A qualitative analyst is typically interested in observing and evaluating the technique that an individual uses in executing a particular skill or performing a particular movement pattern.

• For example, a coach standing on the edge of

a pool can tell a diver immediately whether she

under-rotated, over-rotated, or remained

vertical when entering the water.

• Similarly, physiotherapists or athletic

therapists apply their knowledge of movement

proficiency and efficiency to assess the qualityof a client’s movement pattern following an

injury.

• Through qualitative intervention, movement

professionals can offer individuals advice and

guidance on how to perform better.

Knowledge-Based Sensory Observations


Qualitative analysis relies heavily on a movement

professional’s powers of observation as well as on

their thorough understanding of the techniques and biomechanical principles related to a specific activity,

sport, or exercise.

• Careful visual observation of the movement

pattern and the outcome of a performance if it is

sport-related (e.g., whether a pole vaulter cleared a bar), are essential parts of qualitative analysis.

• The observer may use other senses to gather

qualitative information as well, e.g., by listening to the rhythm of a basketball player’s feet during the

performance of a lay-up shot.

Coaching Requires Qualitative Analysis


Advantages of Qualitative Analysis


Qualitative analyses offer a number of advantages:

• They can be conducted in many different settings.

• They require little or no equipment.

• The person performing the movement can receive immediate verbal feedback about the quality of his

or her efforts.

• If the qualitative analyst keeps a written record of observations and repeats the analysis, the

performer and the movement professional can

assess improvement in performance over time.

Disadvantages of Qualitative Analysis


Qualitative analyses also have limitations:

• If the observer lacks knowledge in a particular

area, the reliability and validity of the results

of the analysis will be questionable.

• Observer bias can influence the results of the

assessment.

• If an activity takes place at a high rate of speed—a golf swing, for example—or if a movement

is relatively small and difficult to attempt, a

qualitative approach may not work.

• In such cases, the movement professional may

choose to incorporate quantitative methods of

analysis as well.

Quantitative Analysis of Human

Movement


Quantitative analysis of human movement uses instruments to generate numerical datato measure and quantify the movement being observed.

• For example, a coach might use a stopwatch to time runners completing a 200 m sprint.

• Similarly, phsiotherapists and orthopedic surgeons

use a stopwatch to conduct a “Timed Up and Go

(TUG) Test” to determine the severity of disability

of a person who needs hip replacement surgery.

• More complex quantitative analysis might involve image-based motion analysis, automatic marker-

tracking systems, and force or pressure plates to

measure foot-strike patterns of athletes.

Who Uses Quantitative Analysis?


The complex mathematical models upon which quantitative analysis often depends may be of little practical use to a teacher or coach.

• It is mainly researchers who use quantitative

movement analysis of a complex nature.

• For example, researchers conducted an ambitious quantitative analysis of Usain Bolt’s astounding

200 m sprint at the 2009 World Championships in

Berlin, Germany.

• The researchers used measurements that

approximated conditions at the time (e.g.,

temperature, altitude, and Bolt’s surface area)as well as data from a velocity tracking device to

determine Bolt’s maximum power output and other

information.

Quantitative Analysis in a Laboratory


Advantages of Quantitative Analysis


Quantitative analyses offer the following advantages:

• They do not rely on an observer’s immediate

knowledge stored in memory but rather on the expertise of those operating the instruments

used to gather and analyze data.

• These instruments can provide data with a high degree of accuracy and reliability, thus

circumventing an observer’s bias.

• Sophisticated quantitative measurement systems allow complex movements—some occurring

at high rates of speed or others too fine to be

detected by the unaided eye—to be captured for later analysis.

Quantitative Analysis & Olympic Wins


Disadvantages of Quantitative Analysis


Quantitative analyses can have limitations:

• They often require expensive equipment and

software.

• Analysts conducting complex quantitative analyses require high levels of technical skills to

operate equipment and generate and analyze data.

• A quantitative analysis might be restricted to a laboratory setting. Lab-based studies may not

replicate the real-world conditions of a sport

or activity as effectively as a field-based study.

• Quantitative analyses can be time-consuming to

complete.



~ ~ ~

“How does qualitative analysis compare with quantitative analysis in terms of

purpose and methods?”

Lesson 13.2


SUMMARY

There are two main methods of analyzing human movement: qualitative analysis and quantitative analysis.

• Qualitative analysis describes movement and

techniques primarily by using non-numerical

information such as knowledge-based sensory observations.

• Quantitative analysis uses instruments to

generate numerical data related to movement.

• Physical education teachers, coaches, athletes,

physiotherapists, kinesiologists, gait analysts, and

judges of artistic sports use qualitative analysis.

• Mainly researchers use quantitative analysis.

Lesson 13.3


BIOMECHANICAL ANALYSIS PART 1

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• (a) The Biomechanics of Walking

• (b) The Biomechanics of a Soccer Kick

Focussing Question


~ ~ ~

“How can we analyze human movement from a biomechanical perspective?”

The Biomechanical Perspective


To analyze movement from a biomechanical perspective, we must simultaneously apply our understanding of the following:

• The various internal and external forces acting on

the human body

• The seven principles of biomechanics

• The anatomical structure of the human body

Example 1: Walking


The force of gravity plays a major role in our walking proficiency from toddlerhood to our senior years.

• Gravity works in opposition to a toddler who tries

to maintain an upright position while learning to

walk.

• To counter the effects of gravity, at least minimal

leg strength is required as well as an ability to

balance on one leg.

• Through practice, the child makes gains in neural

control of musculature and in muscle strength,

this increasing his or her ability to counter the effects of gravity.

Walking and the Principle of Stability

Learning to walk provides a good example of the principle of stability in action.

• To prevent a fall, a

toddler takes shortsteps forward with

feet flat and in a wide

stance.

• This wide stance is

facilitated by pointing

the toes outward.

• The wide stance

increases the width

of the toddler’s base of support, thus

increasing the child’s

stability.


Walking and Principle 4


Over time, a child acquires a more mature, proficient walking pattern.

• This more proficient pattern of walking is

characterized by an increased stride length.

• The increased stride length allows a greater

application of force (i.e., impulse) by the foot

against the ground at push-off.

• This action, therefore, demonstrates

biomechanical principle 4, the impulse-momentum

relationship, which states: The greater the applied impulse, the greater the increase in velocity.

Walking and Principle 5


As the child gains greater control of his or herbalance, out-toeing is reduced and the baseof support narrows.

• This narrowed base of support allows more

force to be applied in a forward-backward

direction.

• Eventually, the child will grow up and demonstrate

the mature, proficient walking pattern of a young

adult.

• This example illustrates biomechanical principle 5:

Movement usually occurs in the direction opposite

that of the applied force.

The Effects of Aging on Walking


Over time, disease, injury, and natural aging processes reduce a person’s walking proficiency.

• Aging individuals who experience a loss of muscle

mass and muscle strength may shorten their

stride length or out-toe a little more in an effort to become more stable.

• With regular physical activity, the ability to walk

with a high degree of proficiency can generally be maintained throughout the human lifespan.

Example 2: Kicking a Soccer Ball


Our ability to kick a ball develops rapidly between the ages of four and six, and by the age of nine the pattern is mature.

• There are distinctly observable biomechanical

differences between a highly proficient kicker and

a beginning kicker.

• Proficient kickers demonstrate a refined and

consistent movement pattern whereas novices

demonstrate a variable and inconsistent one.

• A successful kick is usually defined either in terms

of the velocity of the ball, or the accuracy of

direction of the kick, which relies on the positionof the “plant” (non-kicking) foot and hip position at

impact.

Forces Involved in a Soccer Kick


A thorough qualitative analysis of a free kick in soccer requires an understanding ofmultiple external and internal forces acting on the ball, the player, and the turf that supports them.

• For example, from the moment the ball leaves the

toe of a soccer player, gravity acts on the mass of the ball, giving it weight and resisting its upward

motion.

• Wind is another external force that can slow down, speed up, or push the ball sideways as it hurtles

toward the goal.

• Pushing down on the ground with the non-kicking

foot generates ground reaction force, which helps

the soccer player impart force to the ball.

The Effect of Ground Reaction Force


If the player taking the kick is right-footed, she will need to plant her left foot on the ground as her right leg swings and makes contact with theball.

• If her plant foot slides as she attempts to makethe kick, she will generate little ground reaction

force and the resulting kick will be weak.

• If the plant foot stays in contact with the ground,

it will generate a strong ground reaction force and

the resulting force will be strong.

• To prevent her foot from sliding, the player’s shoes have cleats to increase friction.

A Successful Soccer Kick


Analyzing a Soccer Kick Qualitatively


A soccer kick illustrates several other biomechanical concepts and principles:

• The player’s running approach toward the ball

creates momentum and permits a long angularswing of her kicking leg toward the ball.

• The kicking leg acts as a third class lever in

propelling the ball forward toward the goal cage.

• Maximum velocity is imparted to the ball as a

result of sequenced movements, beginning with

flexion at the hip joint, followed by extension at the knee, and then dorsiflexion at the ankle. This

demonstrates biomechanical principle 3.

Analyzing a Soccer Kick Qualitatively


A successful soccer kick also demonstrates biomechanical principles 1 and 4:

• As the kicking leg swings to kick the ball, the

player moves her arms in an effort to keep her centre of mass positioned over the supporting leg.

• When the kicking foot contacts the ball, a force

is applied to the ball over a period of time. The application of this pushing force over time—or

impulse—causes the ball to move.

• If the foot makes contact with the ball such thatthe applied force does not act through the ball’s

centre of mass, the ball will spin. This spinning

action allows the ball to bend as it moves towardthe goal cage.



~ ~ ~

“How can we analyze human movement from a biomechanical perspective?”

Lesson 13.3


SUMMARY

• All human movement—including everyday actions

such as walking as well as sports-related actions

such as kicking a soccer ball—can be analyzed qualitatively from a biomechanical perspective.

• Qualitative movement analysis involves

simultaneous application of knowledge of internaland external forces acting on the human body, the

principles of biomechanics, and human anatomy.

• Changes in walking patterns from toddlerhood to

our senior years demonstrate the effects of gravity

and biomechanical principles 1, 4, and 5.

• A successful soccer kick demonstrates biomechanical principles 1, 3, and 4.

Lesson 13.4


BIOMECHANICAL ANALYSIS PART 2

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• (a) The Biomechanics of a Wrist Shot

• (b) Computerized Motion Analysis

Focussing Question


~ ~ ~

“In what ways can we conduct a ‘biomechanical breakdown’ ofhuman movement patterns?”

Example 3: Taking a Wrist Shot


In the individual skills competition in floorhockey, “shoot for accuracy” is one of fivedifferent tasks that make up the event.

• Athletes shoot on goal from a distance of 5 m.

• The goal cage is divided into six scoring areas,

with the highest scores allotted to shots that enterthe upper right- and left-hand corners.

• Players have five opportunities to propel a 20 cm

diameter felt ring, or puck, at the net to scorepoints.

• Players attempt to elevate the puck using a wrist

shot, applying the same biomechanical principlesas those used for a wrist shot in ice hockey.

Using the Stick as a Lever


From a qualitative perspective, propelling the puck requires the athlete to use his or her stick as a lever.

• The pull of the top hand on the stick provides the

effort force.

• The puck represents the resistance (or load) to be moved.

• The fulcrum (or axis of rotation) exists at the

location of the player’s bottom hand, which grips the stick about mid-way down the shaft.

Ground Reaction Force and Principle 1


As the player uses his or her arms along with the stick as a lever, the player is also stepping into the shot.

• He pushes backward with his back foot to create a

ground reaction force.

• This ground reaction force directs his body and the puck in a forward direction.

• His front foot, in turn, plants and his arms swing

around his body, in an effort to keep his centre of mass over this new base of support and to

maintain his balance (biomechanical principle 1).

Friction, Gravity, and Momentum


The forces of friction and gravity act on the puck, and the shooter imparts momentum to it.

• As the puck slides across the playing surface, a

frictional force arises between the puck and thesurface, opposing the puck’s forward motion.

• The force of gravity also acts on the puck from the

moment it leaves the player’s stick.

• Whether or not the puck enters the goal cage in

the air or along the ground depends on the angle

at which it leaves the stick, as well as the amountof momentum that is imparted to the puck by the

shooter.

The Impulse-Momentum Relationship


The shooter can increase the amount of momentum and the velocity imparted to the puck.

• The player can accomplish this by increasing

the amount of impulse, or the time over which a

pushing force is applied to the puck.

• Impulse is increased by starting the shot from a

position behind the body, stepping into the shot,

and applying a force as the stick moves forwarduntil the point of release.

• These actions demonstrate biomechanical

principle 4 (the impulse-momentum relationship).

Maximizing Force


A wrist shot in floor hockey or ice hockey also demonstrates biomechanical principle 2.

• The amount of force applied to the puck is

increased by the use of leg drive, and by sequencing the use of all the muscles and joints in

the arm.

• The wrist shot relies on the sequenced use of the muscles and joints of the upper arm followed

by those in the forearm, finishing with a rapid

extension of the wrist.

Example 4: Computerized Motion Analysis


For decades now, motion capture has played

an important role in biomechanical assessmentand analysis.

• Motion capture is the process of videorecording the movements of objects or people.

• Motion capture is used in sports and in military,

entertainment, robotics, and medical applications.

• In the creation of films and video games, the term

refers to recording the actions of human actors,

and using that information to animate digitalcharacter models in 2D or 3D computer animation.

• In the world of filmmaking, motion capture is often

referred to as “performance capture.”

Motion-Capture Systems


For many years, sport scientists have used computerized motion-capture systems—high-speed digital video cameras connected to powerful computers—to evaluate the performance of elite athletes.

• Increasingly, teachers, coaches, and trainers are

using this technology to conduct a “biomechanical breakdown” of the movement patterns of students

and amateur athletes, too.

• This type of analysis can slow down activities such as running, jumping, throwing, and striking

in order to pinpoint energy leaks in the body’s

movement patterns that can reduce an athlete’s power and efficiency.

Computerized Motion Analysis & Training


Analyzing a Jump Shot in Basketball


The data captured by computerized motion analysis can break down a jump shot in basketball.

• The jump shot—which usually takes about one

second—is broken down into nine separate

actions, or phases.

• Viewing each phase separately can reveal

where an athlete is making one or more errors in

executing a shot.

• When the errors are corrected, the

player’s shooting performance will improve.

Coach’s Eye


Coach’s Eye is a multimedia application used in computerized motion analysis.

• This program is popular with physical education

teachers because it allows instant feedback forstudents.

• It can record a student performing a skill and then

play it backwards, in slow motion, or frame by frame.

• The person using the program can also

draw on screen or record a playback withverbal comments.

Ubersense


Ubersense is used by countless teachers, students, coaches and athletes to improvetechnique and performance in almost every sport or activity.

• Ubersense is a free mobile app that lets usersrecord movements in high definition.

• The movements can be analyzed using slow

motion and drawings.

• Users can also watch drills from professional

coaches and share videos.



~ ~ ~

“In what ways can we conduct a ‘biomechanical breakdown’ ofhuman movement patterns?”

Lesson 13.4


SUMMARY

• Biomechanical movement analysis often relies

on an analyst’s powers of sensory

observation. Additionally, computerized motionanalysis is being used to “break down” human

movement patterns in order to help correct

errors.

• Taking a wrist shot in floor hockey demonstrates a

number of biomechanical concepts (e.g., the stick

is used as a lever) as well as principles 1, 2, and 4.

• Increasingly, teachers, coaches, and trainers are

using motion-capture systems such as Coach’s

Eye and Ubersense to conduct a “biomechanical

breakdown” of human movement patterns.

Documents

Lesson 13.1 APPLIEDBIOMECHANICSedhswilson.weebly.com/uploads/5/6/1/3/5613731/chapter_13.pdf · Human Movement Analysis ... Biomechanical concepts and principles provide a basis for