Chapter 18: Moving Objects: Throwing, Striking, and Kicking

1. Chapter 18:Moving Objects:Throwing, Striking, and Kicking KINESIOLOGY Scientific Basis of Human Motion, 10th edition Luttgens & Hamilton Presentation Created by TK Koesterer, Ph.D., ATC Humboldt State University

2. Objectives 1. Classify activities involving sequential throwing, kicking, or striking patterns according to the nature of the force application 2. Name and discuss anatomical and mechanical factors that apply to representative throwing, kicking, or striking activities 3. Perform a kinesiological analysis of someone engaging in a sequential throwing, kicking, or striking skill under each of these force application conditions: momentary contact; projection; continuous application

3. 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

4. Joint Action Patterns • Each pattern involves a preparatory movement referred to as a backswing, or wind up • Followed by the establishment of a base of support prior to initiation of • Force phase • Ending in a follow through

5. Overarm Pattern • Characterized by rotation of the shoulder joint • Backswing: abducted arm rotates laterally • Force phase: arm rotates medially • Some elbow extension, wrist flexion, and spinal rotation • Rotation of pelvis at the hip joint of opposite limb, resulting in medial rotation of the thigh

6. Overarm Pattern Fig 18.2

7. Underarm Pattern • Consist of forward movement of extended arm • Basic joint action is arm flexion Fig 18.4

8. 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 the pelvic action and spinal rotation • Spine laterally flexes toward throwing arm • Elbow maintains or is extended slightly • Wrist flexion may also be part of the action

9. Sidearm Pattern Fig 18.5

10. 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 • Left foot is stabilized • Pelvis is fixed of the thing & rotated to left • Right lags behind; abducted & hyperextension • Right flexes at hip followed by knee extension

11. KIckIng Pattern Fig 18.6

12. 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 at the desire point released

13. PRINCIPLES RELATING TO THROWING, STRIKING AND KICKINGAnatomical Principles 1. Muscles contract more forcefully if they are first put on a stretch 2. Unnecessary movements and tension mean awkwardness and unnecessary fatigue 3. Skillful performance can be developed only by practice of the technique 4. Most efficient type of movement is ballistic 5. Appropriate levers should be used to the task

14. Mechanical PrinciplesThrowing 1. The object will move only if the force is sufficient magnitude to overcomes the object’s inertia 2. The pattern and range of joint movements depends on the purpose of the movement 3. 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

15. Mechanical PrinciplesThrowing 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 move an object 6. For a change in momentum to occur, force must be applied over time

16. Mechanical PrinciplesThrowing 7. Force applied in line with an object’s center of gravity will result in linear motion of the object, provided it is freely movable 8. 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

17. Striking, Hitting, and Kicking Major factors 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

18. Mechanical PrinciplesStriking, Hitting, and Kicking 1. The direction in which the object moves is determined by direction of force applied to it 2. Momentum is conserved in all collisions 3. Any change in momentum of 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

19. Mechanical PrinciplesStriking, Hitting, and Kicking 5. 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

20. Mechanical PrinciplesStriking, Hitting, and Kicking 8. 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: 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

21. EXAMPLES OF THROWING AND STRIKINGAnalysis of the Overarm Throw • This analysis includes joint actions, muscle activity, and mechanics of the upper extremity only

22. Analysis of the Overarm ThrowBackswing • 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

23. Analysis of the Overarm ThrowForce Phases • Immediately following establishment of a base of support, pelvic and then trunk rotation, are accompanied by lateral flexion to the left • Trunk motion cause 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

24. Analysis of the Overarm ThrowFollow-through • Actions from ball release until the momentum develop in the arm can be safely dissipated as the arm continues across the body in a downward direction • A forward step is also used

25. Analysis of the Overarm Throw • Actions proceed form proximal (more massive) to distal (lighter) segments • Momentum is transferred form 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, transfer momentum

26. Analysis of the Overarm ThrowShoulder 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

27. Analysis of the Overarm ThrowOther Muscles Involved • Biceps has peak activity as the elbow is flexed late into backswing and at the beginning of force phase, and again during follow-through • Latissimus dorsi, active during medial rotation, remain active eccentrically during follow-through

28. Analysis of the Overarm ThrowStretch Reflex • An important facilitating mechanism is 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

29. Analysis of the Overarm ThrowTrunk Rotation • 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

30. Analysis of the Overarm ThrowExtensor Thrust Reflex • May act on both the upper and lower extremities • Increasing pressure on the palmar side of the hand as the arm is being accelerated forward may facilitate the arm extensor muscles • Weight transfer to forward foot, pacinian corpuscles are stimulated by increased pressure, resulting in a facilitation of the lower limb extensor muscles

31. Analysis: Forehand Drive in TennisDescription • Objective is to send the ball over the net and deep into the opponent’s court close to the base line Fig 18.7

32. 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 its faced turned slightly down • Players weight is over the rear foot

33. Analysis: Forehand Drive in TennisForward 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 froward foot as racket is swung forward and up • Racket face is perpendicular to court at ball impact, imparting topspin to the ball

34. Analysis: Forehand Drive in TennisFollow-Through • Follow-through continues toward the intended target, with the racket arm swinging across the body and up toward the chin

35. Analysis: Forehand Drive in Tennis Anatomical Factors • 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

36. Analysis: Forehand Drive in Tennis Anatomical Factors • Resistance Point: at the center of gravity of the trunk-arm-racket lever • May be considered the point of contact with the ball • Additional Lever actions: due to rotation of the spine, horizontal adduction at shoulder, and flexion at wrist • Muscular Strength: shoulder abductors, assisting with swing, & rotating spine and pelvis

37. 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 placement • 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

38. Analysis: Forehand Drive in Tennis Mechanical Analysis 1. Arm fully extended to increase lever length 2. Effort to resist force of ball, is less when the racket lever arm is shortened 3. Take less time to swing a shortened racket lever into position 4. Concentration of mass at shoulder level moving forward at impact ensures maximum speed of striking

39. Analysis: Forehand Drive in Tennis Mechanical Analysis 5. Skillful player use a heavier racket, greater mass of implement, greater striking force 6. A new ball and well strung racket ensure good coefficient of restitution (elasticity) 7. Shift weight while striking the ball increases ground reactive force imparted to body & ball 8. Firm wrist and grip are essential for maximum impulse to be applied by the racket to the ball

40. Analysis: Forehand Drive in Tennis Mechanical Analysis 9. Direction of struck ball is determined by: a. Direction of implement at impact b. Relation of striking force to ball’s center of gravity, control of spin c. Firmness of grip and wrist at impact d. Angle of incidence