Development of Ballistic Skills

1
chapter 7

• Development of Ballistic Skills

2
Ballistic Skills

• An individual applies force to an object in order
  to project it.
• Common ballistic skills include throwing,
  kicking, and striking.

3
Overarm Throwing

• Throwing takes many forms
• Two-hand underhand
• One-hand underhand
• Sidearm
• Two-hand overarm
• One-hand overarm
• The most common in sport games is the one-hand
  overarm throw.

4
Gauging Throwing Skill

• Product measures (outcome)
• Accuracy
• Distance
• Ball velocity
• Process measures (movement pattern)
• Developmental sequences
• Each has advantages and disadvantages, but
  product measures often reflect skill as well as
  body growth and maturation during childhood and
  adolescence.

5
A Beginning Thrower

• (continued)

Drawn from film tracings available from the
Motor Development Film Collection, Bowling Green
State University
6
A Beginning Thrower (continued)
(continued)
Drawn from film tracings available from the
Motor Development Film Collection, Bowling Green
State University
7
A Beginning Thrower (continued)
Click image to view video
8
Characteristics of Early Overarm Throwing

• Early overarm throwing consists mostly of arm
  action.
• The elbow points up.
• The throw is executed by elbow extension alone.

9
A Proficient Thrower
Click image to view video
10
Proficient Overarm Throwing for Force

• Preparatory windup used (weight shifts and trunk
  rotates back, arm swings).
• Use of opposite leg, long step, and
  differentiated trunk rotation.
• Upper arm and forearm lag back.
• Movements are sequential to transfer momentum.

11
Developmental Changes in Overarm Throwing

• Trunk action
• None or forwardbackward movement
• Block rotation
• Differentiated rotation
• Backswing
• None
• Shoulder flexion
• Upward backswing
• Downward, circular backswing

(continued)
12
Developmental Changes in Overarm Throwing
(continued)

• Foot action
• No step
• Homolateral step
• Short contralateral step
• Long contralateral step

(continued)
13
Developmental Changes in Overarm Throwing
(continued)

• Upper arm action
• Oblique
• Aligned but independent
• Lag
• Forearm action
• No lag
• Lag
• Delayed lag

14
Progression in Childhood

• Throwers do not achieve the same step for each
  body component at the same time.
• Some combinations of steps are observed more
  frequently than others are observed.
• Not everyone reaches the highest step in each
  component girls and women often remain in
  intermediate steps.

15
Throwing in Adulthood

• Older adults demonstrate moderately advanced
  steps.
• Gender differences are observed.
• Ball velocities are moderate.
• Musculoskeletal constraints might influence the
  movement patterns used.
• (continued)

16
Throwing in Adulthood (continued)

• Change is usually slight rather than rapid, is
  more often an increase in variability, and is
  usually a decline.
• Change is typically in the control of movements
  (slowed speed or decreased range of motion)
  rather than coordination of movements.

17
Throwing for Accuracy

• Throwers may use lower developmental steps for
  accuracy throws than for forceful throws.
• If the distance for the accuracy throw still
  requires force, little change would be noted for
  that individual.

18
Kicking

• The ball is struck this can be difficult for
  children if the ball is moving.
• Children must have perceptual abilities and
  eyefoot coordination to make contact.

19
Characteristics of Early Kicking

• No step with nonkicking leg.
• Kicking leg pushes forward.

Click image to view video
20
Intermediate Kicker
Click image to view video
21
Proficient Kicking

• Preparatory windup used (trunk rotated back,
  kicking leg cocked, knee bent).
• Trunk rotates forward.
• Movement is sequential, with thigh rotating
  forward then lower leg extending.
• Arms move in opposition to the legs.

22
Proficient Kicker
Click image to view video
23
Developmental Changes in Kicking

• Movement pattern changes are not well documented.
• Developmental steps have not been validated.

24
Punting

• The ball is dropped from the hands.
• Punting is more difficult for children than
  kicking.

25
Characteristics of Early Punting

• Ball is tossed up rather than dropped.
• Punter often contacts ball with toes rather
  than with instep.

Drawn from film tracings available from the
Motor Development Film Collection, Bowling Green
State University
26
Proficient Punting

• Arms are extended to drop ball before final
  stride is taken.
• Arms then drop to sides and move into opposition
  with legs.
• Punter leaps on to supporting leg, swings punting
  leg vigorously up to contact.
• Punting leg is kept straight, with toes pointed.

27
An Advanced Punter
Drawn from film tracings available from the
Motor Development Film Collection, Bowling Green
State University
28
Developmental Changes in Punting Arms

• Ball-release phase
• Upward toss
• Late drop from chest height
• Late drop from waist height
• Early drop from chest height
• Ball-contact phase
• Arms drop
• Arms abduct
• Arm opposition

29
Developmental Changes in Punting Legs

• Ball-contact phase
• No short step, ankle flexed
• Long step, ankle extended
• Leap and hop

30
Sidearm Striking

• Various body parts can be used.
• Implements can be used.
• Mechanical principles are similar for all
  striking tasks.
• Focus here is on one-hand sidearm and one-hand
  overarm with an implement.
• Principles can be applied to other striking tasks.

31
Characteristics of Early Sidearm Striking

• Chopping motion (elbow extension)
• Little leg and trunk movement

Click image to view video
32
Intermediate Striker
Drawn from film tracings available from the
Motor Development Film Collection, Bowling Green
State University
Click image to view video
33
Proficient Sidearm Striking

• Sideways preparatory stance and a long step
• Differentiated trunk rotation
• Horizontal swing through large range of motion,
  with arm extended before contact
• Sequential movements

Click image to view video
34
Developmental Changes in Sidearm Striking

• Sequences for foot and trunk in the overarm throw
  can be used.
• Trend to use trunk rotation (none, then blocked,
  then differentiated).
• Plane of the swing progresses from vertical to
  horizontal.
• (continued)

35
Developmental Changes in Sidearm Striking
(continued)

• Grip changes from power grip to shake-hands
  grip.
• Elbows are away from the body and extended before
  contact.

36
Overarm Striking

• Without an implement (volleyball serve)
• With an implement (tennis serve)

37
Characteristics of Early Overarm Striking

• Limited trunk rotation
• Swing with a collapsed elbow
• Little or no lagging with the swing forward
• Looks much like early throwing

38
Proficient Overarm Striking

• Lower and upper trunk are rotated more than 90
  degrees.
• Elbow is held between 90 and 119 degrees at start
  of forward movement.
• Racket lags behind arm in forward swing.
• Movement is sequential.

39
Developmental Changes in Overarm Striking

• Trunk, upper and lower arm, and leg sequences
  similar to overarm throwing
• Preparatory trunk action
• No trunk
• Minimal trunk rotation
• Total trunk rotation
• (continued)

40
Developmental Changes in Overarm Striking
(continued)

• Elbow action in ball-contact phase
• Very small or very large angle
• Intermediate angle (289 degrees)
• Ideal angle (90119 degrees)
• Spinal and pelvic range of motion
• Less than 45 degrees
• Rotation of 45 to 89 degrees
• Rotation of 90 degrees or more

(continued)
41
Developmental Changes in Overarm Striking
(continued)

• Racket action
• No racket lag
• Racket lag
• Delayed racket lag

42
Older Adult Striking

• Jagacinski, Greenberg, Liao (1997)
• Studied iron shot (did not require maximal
  force).
• Older golfers reach peak force earlier in swing.
• Older golfers may need to exert more force for
  the same shot compared with younger golfers.
• A few older golfers were less accurate than
  younger golfers but most were just as accurate.
• (continued)

43
Older Adult Striking (continued)

• Haywood Williams (1995)
• Studied tennis first serve.
• Studied older servers at moderate levels.
• Two former teaching professionals were
  categorized at the highest levels (they
  maintained the coordination of movements).

44
Ballistic Skills Summary

• Proficient performance demonstrates the
  mechanical principles.
• Developmental trends are toward proficient
  mechanical performance.
• A forward step and more trunk rotation are used.
• Trunk rotation is differentiated.
• (continued)

45
Ballistic Skills Summary (continued)

• Projecting limb shows more and more lag.
• Probably not all individuals reach highest steps.
• Older adults appear to maintain the coordination
  of ballistic movements fairly well.

46
Assessment of Ballistic Skills

• Developmental sequences can be used as
  checklists.
• Individuals are considered to be in a
  developmental step if the majority of a set
  number of executions (typically five) are in that
  category.
• Observation should be conducted from the
  appropriate direction.
• Side views show forward step, trunk action, and
  lagging.
• Rear views show arm angles.