Transcript 15.hamilton11e_ppt_18(1)

Chapter 18:
Moving Objects:
Throwing, Striking, and
Kicking
KINESIOLOGY
Scientific Basis of Human Motion, 11th edition
Hamilton, Weimar & Luttgens
Presentation Created by
TK Koesterer, Ph.D., ATC
Humboldt State University
Revised by Hamilton & Weimar
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Objectives
Classify activities involving throwing, kicking,
or striking patterns according to the nature
of the force application.
2. Name and discuss anatomical and
mechanical factors that apply to throwing,
kicking, or striking activities.
3. Perform a kinesiological analysis of a
sequential throwing, kicking, or striking skill
under each of these force application
conditions: momentary contact; projection;
continuous application.
1.
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SEQUENTIAL MOVEMENTS

Movement of body segments resulting in the
production of summated velocity at the end of
the chain of segments.
 Path produced is curvilinear.
 Most frequently used to produce high
velocities in external objects.
 Depending on objective of skill (speed,
accuracy, distance, or combination)
modifications to pattern may be made.
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Joint Action Patterns
Each pattern involves a preparatory
movement referred to as a backswing,
or wind up.
 This is followed by the establishment of
a base of support prior to initiation of
 Force phase
 Ending in a follow through.

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Overarm Pattern

Characterized by rotation of the shoulder
joint.
 Backswing: abducted arm rotates externally.
 Force phase: arm rotates internally.


Some elbow extension, wrist flexion, and spinal
rotation.
Rotation of pelvis at the hip joint of opposite limb,
resulting in internal rotation of the thigh.
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Overarm Pattern
Fig 18.2
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Underarm Pattern
Consists of forward movement of
extended arm.
 Basic joint action is arm flexion.

Fig 18.4
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Sidearm Pattern





Basic movement is medial rotation of the
pelvis on the opposite hip with the arm
usually in an abducted position.
Arm is moved forward due to pelvic and
spinal rotation.
Spine laterally flexes toward throwing arm.
Elbow maintains or is extended slightly.
Wrist flexion may also be part of the action.
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Sidearm Pattern
Fig 18.5
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Kicking Pattern





Is a modification of a locomotor pattern in
which force is imparted to an external object
during forward swing of non-weight bearing
limb.
Non-kicking foot is stabilized.
Pelvis is fixed over thigh & rotated toward
support leg.
Kicking leg lags behind; abduction &
hyperextension.
Kicking leg flexes at hip followed by knee
extension.
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Kicking Pattern
Fig 18.6
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Nature of Force Application
 Momentary
Contact: striking and
kicking.

contact made with an object by a moving
body part or implement.
 Projection: throwing
 an object is given some velocity and is
released at the desired point.
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PRINCIPLES RELATING TO
THROWING, STRIKING AND
KICKING
Anatomical Principles
 Muscles contract more forcefully if they are




first put on stretch.
Unnecessary movements and tension mean
awkwardness and unnecessary fatigue.
Skillful performance can be developed only
by practice of the technique.
Most efficient type of movement is ballistic.
Appropriate levers should be used for the
task.
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Mechanical Principles
Throwing
1.
2.
3.
The object will move only if the force is of
sufficient magnitude to overcome the
object’s inertia.
The pattern and range of joint movements
depends on the purpose of the motion.
Force exerted by the body will be
transferred to an external object in
proportion to the effectiveness of the
counterforce of the feet against the ground.
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Mechanical Principles
Throwing
4.
5.
6.
Linear velocity is imparted to external
objects as a result of angular velocity
of the body segments.
Optimum summation of internal force
is needed if maximum force is to be
applied to an object.
For a change in momentum to occur,
force must be applied over time.
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Mechanical Principles
Throwing
7.
8.
Force applied in line with an object’s
center of gravity will result in linear
motion of the object, provided it is
freely movable.
If the force applied to a freely movable
object is not in line with it’s center of
gravity, it will result in rotary motion of
the object.
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Striking, Hitting, and Kicking
Major factors in the speed of a struck ball:
1. Speed of incoming ball & striking implement.
2. Mass of the ball & striking implement.
3. Elasticity between ball & striking implement.
4. Direction of ball & implement at impact.
5. Point of impact between ball & implement.
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Mechanical Principles
Striking, Hitting, and Kicking
1.
2.
3.
4.
The direction in which the object moves is
determined by direction of force applied.
Momentum is conserved in all collisions.
Any change in momentum of colliding
objects is related to force and duration of
collision.
The greater the velocity of the approaching
ball, the greater the velocity of the ball in the
opposite direction after it is struck.
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Mechanical Principles
Striking, Hitting, and Kicking
The greater the velocity of the striking
implement at the moment of contact, the
greater the velocity of the struck ball.
6. The greater the mass of the ball, up to a
point, the greater its velocity after being
struck.
7. The greater the mass of the striking
implement, up to a point, the greater the
striking force, and hence the greater the
speed of the struck ball.
5.
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Mechanical Principles
Striking, Hitting, and Kicking
The higher the coefficient of restitution
(elasticity) of the ball and of the striking
implement, the greater the speed of the
struck ball.
9. The direction taken by the struck ball is
determined by four factors:
8.
1.
2.
3.
4.
Direction of striking implement at contact;
Relation of the striking force to ball’s center of
gravity;
Degree of firmness of grip and wrist at contact;
Laws of rebound.
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EXAMPLES OF THROWING
AND STRIKING
Analysis of the Overarm Throw

This analysis includes joint actions,
muscle activity, and mechanics of the
upper extremity only.
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Analysis of the Overarm
Throw
Backswing

The purpose is to place joints in optimal
position and involve the greatest number of
segments in preparation for the force phase.
 Includes pelvic and trunk rotation in the
opposite direction, horizontal abduction and
lateral rotation at shoulder joint with elbow
flexion and wrist hyperextension.
 A forward step is taken with the opposite foot,
permits greatest ROM in trunk and pelvis, and
a large base of support.
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Analysis of the Overarm
Throw
Force Phase

Immediately following establishment of a base
of support, pelvis and then trunk rotation are
accompanied by lateral flexion to the left.
 Trunk motion causes increased horizontal
abduction with continuing lateral rotation at
the shoulder joint.
 Elbow extension is followed by rapid medial
rotation at shoulder, forearm pronation, and
then flexion and ulnar deviation at wrist.
 Ends with release of the ball.
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Analysis of the Overarm
Throw
Follow-through
From ball release until the momentum in
the arm can be safely dissipated as the
arm continues across the body in a
downward direction.
 A forward step is also used.

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Analysis of the Overarm
Throw

Actions proceed from proximal (more
massive) to distal (lighter) segments.
 Momentum is transferred from more massive
(proximal) to less massive (distal) segments,
significantly increasing their velocity.
 Linear velocity at the end of the chain (ball at
release) often can exceed 90 mph.
 Legs provide the stable base, contribute
significantly to force production and transfer
of momentum.
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Analysis of the Overarm
Throw
Shoulder Joint Actions

Lateral rotation preceding the medial rotation
is controlled by eccentric contraction of
medial rotators followed by concentric
contraction of the same medial rotators.
 Height of humerus is controlled by static
contraction of middle deltoid.
 Deltoid & supraspinatous contract
concentrically during backswing to position
upper arm, and eccentrically during the
follow-through to help decelerate the arm.
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Analysis of the Overarm
Throw
Other Muscles Involved

Biceps has peak activity as the elbow is
flexed late into backswing, at the beginning of
force phase, and again during follow-through.
 Latissimus dorsi, active during medial
rotation, remains active eccentrically during
follow-through.
 Trunk rotators are also active.
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Analysis of the Overarm
Throw
Stretch Reflex

An important facilitating mechanism in
accelerating the lagging distal segments.
 The more rapid the stretch (eccentric
contraction), the greater will be the facilitating
effect on the resulting concentric contraction
of the same muscle.
 Forces can be summated more appropriately.
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Analysis of the Overarm
Throw
Other Reflexes

As the trunk rotates under the stationary head
(eyes focused on the target), tonic neck reflex
may facilitate the strong acceleration occurring
during the force phase.


Asymmetric tonic neck reflex facilitates the
shoulder abductor and elbow extensors on the chin
side, precisely the arm position at release.
Increasing pressure on the hand and weight
transfer to forward foot may produce an extensor
thrust reflex.


Facilitation of the lower limb extensor muscles.
Facilitation of arm extensors.
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Analysis: Forehand Drive in
Tennis
Description

Objective is to send
the ball over the net
and deep into the
opponent’s court
close to the base
line.
Fig 18.7
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Analysis: Forehand Drive in
Tennis

Starting Position: Player faces the net with
feet about shoulder width apart and the
weight of the balls of the feet.

Racket is held with an hand shake grip.

Backswing: Player pivots entire body so that
the non-racket side is toward the net.
 Racket is taken back at shoulder level, with
head of racket above the wrist and the face
turned slightly down.
 Players’ weight is over the rear foot.
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Analysis: Forehand Drive in
Tennis
Forward Swing
 Player flexes at the knees to drop racket
below intended contact point, keeping racket
head above the wrist.
 Steps toward the ball with non-racket foot.
 Pelvis and spine rotate so trunk faces
forward, and weight is shifted to forward foot
as racket is swung forward and up.
 Racket face is perpendicular to court at ball
impact, imparting topspin to the ball.
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Analysis:
Forehand Drive in Tennis
Follow-Through
 Follow-through continues toward the
intended target, with the racket arm
swinging across the body and up.
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Analysis: Forehand Drive in
Tennis
Anatomical Factors
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Action is ballistic in nature.
Initiated by muscular force, continued by
momentum, and finally terminated by the
contraction of antagonistic muscles.
Chief levers: arm, trunk, and racket.
Fulcrum: at opposite hip joint.
Point of force application: at a point of the
pelvis representing combined forces of the
muscles producing the movement.
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Analysis: Forehand Drive in
Tennis
Anatomical Factors

Resistance application point: at the center of
gravity of the trunk-arm-racket lever.

May be considered the point of contact with the
ball at the moment of impact.

Additional lever actions due to rotation of the
spine, horizontal adduction at shoulder, and
flexion at wrist.
 Muscular Strength: shoulder abductors
assisting with swing, & rotators of spine and
pelvis.
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Analysis: Forehand Drive in
Tennis
Mechanical Analysis

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Purpose is to return ball in the court, but also
to make it difficult to return.
Requires both high speed and accuracy.
Force of impact: speed of racket at moment of
contact.
Straight backswing: ease of control, but must
overcome inertia.
Circular backswing: greater distance to build
momentum.
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Analysis: Forehand Drive in
Tennis
Mechanical Analysis
 Arm fully extended to increase lever length.
 Effort to resist force of ball is less when the


racket lever arm is shortened.
Take less time to swing a shortened racket
lever into position.
Concentration of mass at shoulder level
moving forward at impact ensures maximum
speed of striking.
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Analysis: Forehand Drive in
Tennis
Mechanical Analysis
 Skillful players use a heavier racket - greater



mass of implement  greater striking force.
A new ball and well strung racket ensure
good coefficient of restitution (elasticity).
Shift weight while striking the ball to
increase ground reaction force imparted to
body & ball.
Firm wrist and grip are essential for
maximum impulse to be applied by the
racket to the ball.
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Analysis: Forehand Drive in
Tennis
Mechanical Analysis
9.
Direction of struck ball is determined
by:
a)
b)
c)
d)
Direction of implement at impact.
Relation of striking force to ball’s center
of gravity, control of spin.
Firmness of grip and wrist at impact.
Angle of incidence.
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Chapter 18:
Moving Objects:
Throwing, Striking, and Kicking
© 2008 McGraw-Hill Higher Education. All Rights Reserved.