Transcript Ch17 Powerpoint

CHAPTER 17:
MOVING OBJECTS:
THROWING, STRIKING, AND
KICKING
KINESIOLOGY
Scientific Basis of Human Motion, 12th edition
Hamilton, Weimar & Luttgens
Presentation Created by
TK Koesterer, Ph.D., ATC
Humboldt State University
Revised by Hamilton & Weimar
McGraw-Hill/Irwin
Copyright © 2012 by The McGraw-Hill Companies, Inc. All rights reserved.
Objectives
1. 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.
17-2
SEQUENTIAL MOVEMENTS
 Movement of body segments resulting in the
production of summated velocity at the end
of the kinetic 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 the pattern may be made.
17-3
Joint Action Patterns
 Each pattern involves a preparatory
movement referred to as a backswing, or
wind up.
 This is followed by establishment of a
base of support prior to initiation of the
force phase.
 Ends in a follow through.
17-4
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.
17-5
Overarm Pattern
Fig 17.2
17-6
Underarm Pattern
 Consists of forward movement of
extended arm.
 Basic joint action is arm flexion.
Fig 17.4
17-7
Sidearm Pattern
 Basic movement is internal rotation of the
pelvis on the opposite hip, 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.
17-8
Sidearm Pattern
Fig 17.5
17-9
Kicking Pattern
 Modification of a locomotor pattern in which
force is imparted to an 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; hip abduction &
hyperextension.
 Kicking leg flexes at hip followed by knee
extension.
17-10
Kicking Pattern
Fig 17.6
17-11
Nature of Force Application
 Momentary Contact: striking and
kicking.
 Sequential movement designed to bring
about 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.
17-12
PRINCIPLES RELATING TO
THROWING, STRIKING AND
KICKING
Anatomical Principles
 Muscles contract more forcefully if they are




first stretched.
Unnecessary movements and tension mean
awkwardness and fatigue.
Skillful performance can be developed only
by practice.
Most efficient type of movement is ballistic.
Appropriate levers should be used.
17-13
Mechanical Principles
Throwing
1. The object will move only if the force is of
sufficient magnitude to overcome the
object’s inertia.
2. The pattern and range of joint movements
depends on the purpose of the motion.
3. Force exerted by the body will be
transferred to an external object in
proportion to the counterforce of the feet
against the ground.
17-14
Mechanical Principles
Throwing
4. Linear velocity is imparted to external
objects as a result of angular velocity of the
body segments.
5. Optimum summation of internal force is
needed if maximum force is to be applied to
an object.
6. For a change in momentum to occur, force
must be applied over time.
17-15
Mechanical Principles
Throwing
7. Force applied in line with an object’s center
of gravity will result in linear motion of the
object.
8. If the force applied to object is not in line
with it’s center of gravity, it will result in
rotary motion of the object.
17-16
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.
17-17
Mechanical Principles
Striking, Hitting, and Kicking
1. The direction in which the object moves is
determined by direction of force applied.
2. Momentum is conserved in all collisions.
3. Any change in momentum in colliding
objects is related to force and duration of
collision.
4. The greater the velocity of the approaching
ball, the greater the velocity of the ball in
the opposite direction after it is struck. 17-18
Mechanical Principles
Striking, Hitting, and Kicking
5. The greater the velocity of the striking
implement at 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 contact.
7. The greater the mass of the striking
implement (up to a point) the greater the
striking force, therefore the greater the
speed of the ball.
17-19
Mechanical Principles
Striking, Hitting, and Kicking
8. The higher the coefficient of 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:
1. Direction of striking implement at contact;
2. Relation of the striking force to ball’s center of
gravity;
3. Degree of firmness of grip and wrist at contact;
4. Laws of rebound.
17-20
EXAMPLES OF THROWING
AND STRIKING
Analysis of the Overarm Throw
 This analysis includes joint actions,
muscle activity, and mechanics of the
upper extremity only.
17-21
Analysis of the Overarm Throw
Backswing
 Places joints in optimal position and involves
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.
 Forward step taken with the opposite foot
permits greatest ROM in trunk and pelvis, and
a large base of support.
17-22
Analysis of the Overarm Throw
Force Phase
 Following establishment of a base of support,
pelvis and then trunk rotation are accompanied
by lateral flexion away from the ball.
 Trunk motion causes increased horizontal
abduction and lateral rotation at the shoulder
joint.
 Elbow extension is followed by rapid medial
rotation at shoulder, forearm pronation, then
flexion and ulnar deviation at wrist.
 Ends with release of the ball.
17-23
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.
17-24
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 the 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
17-25
of momentum.
Analysis of the Overarm Throw
Shoulder Joint Actions
 Lateral rotation preceding the medial rotation,
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
17-26
decelerate the arm.
Analysis of the Overarm Throw
Other Muscles Involved
 Biceps has peak activity as the elbow is flexed
late in 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.
17-27
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.
 To gain greatest benefit, no pause between
wind-up and force phases.
17-28
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 TNR facilitates chin side shoulder
abductors and elbow extensors, precisely the arm
position at release.
 Increased pressure on the hand and weight
transfer to forward foot may produce an extensor
thrust reflex.
 Facilitation of the lower limb extensor muscles.
17-29
 Facilitation of arm extensors.
Analysis: Forehand Drive in
Tennis
Description
 Objective is to send the
ball over the net, deep
into the opponent’s
court close to the base
line.
Fig 17.7
17-30
Analysis: Forehand Drive in
Tennis
Starting Position: Player faces the net with feet
about shoulder width apart, weight on the
balls of the feet.
 Racket is held with a 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, head
of racket above the wrist, face turned slightly
down.
 Weight is over the rear foot.
17-31
Analysis: Forehand Drive in
Tennis
Forward Swing
 Player flexes at the knees, drops racket below
contact point, 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.
17-32
Analysis:
Forehand Drive in Tennis
Follow-Through
 Follow-through continues toward the
intended target, with the racket arm
swinging across the body and up.
17-33
Analysis: Forehand Drive in
Tennis
Anatomical Factors
 Action is ballistic in nature.
 Initiated by muscular force, continued by
momentum, and 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 on the
pelvis representing combined forces of the
muscles producing the movement.
17-34
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 action 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
17-35
pelvis.
Analysis: Forehand Drive in
Tennis
Mechanical Analysis
 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.
17-36
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.
Takes less force to swing a shortened racket
lever into position.
Concentration of mass at shoulder level
moving forward at impact ensures maximum
speed of striking.
17-37
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 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
17-38
racket to the ball.
Analysis: Forehand Drive in
Tennis
Mechanical Analysis

Direction of struck ball is determined
by:




Direction of implement at impact.
Relation of striking force to ball’s center
of gravity (controls spin).
Firmness of grip and wrist at impact.
Angle of incidence.
17-39