HS 325
Ch. 7
Development of Ballistic Skills
Next Learning Lab: Wed, Oct. 4
Dress for activity
Rolle Gym – Section closest to HP building
chapter 7
Development of Ballistic Skills
Ballistic Skills
•An individual applies force to an object in order to project it.
•Common ballistic skills include throwing, kicking, and striking.
Class Overview:
•Developmental Changes in
Throwing
Kicking
Punting
Striking
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.
Gauging Throwing Skill
•Outcome (product) measures
–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.
A Beginning Thrower
(continued)
A Beginning Thrower (continued)
A Beginning Thrower (continued)
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.
A Proficient Thrower
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.
Developmental Changes in Overarm Throwing
Trunk action
•None or forward–backward movement
•Block rotation
•Differentiated rotation
Backswing
•None
•Shoulder flexion
•Upward backswing
•Downward, circular backswing
Developmental Changes in Overarm Throwing (continued)
Foot action
•No step
•Homolateral step
•Short contralateral step
•Long contralateral step
Developmental Changes in Overarm Throwing (continued)
Upper arm action
•Oblique
•Aligned but independent
•Lag
Forearm action
•No lag
•Lag
•Delayed lag
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.
Kicking
•The ball is struck; this can be difficult for children if the ball is moving.
•Children must have perceptual abilities and eye–foot coordination to make contact.
Characteristics of Early Kicking
•No step with nonkicking leg.
•Kicking leg pushes forward.
Intermediate Kicker
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.
Proficient Kicker
Developmental Changes in Kicking
•Movement pattern changes are not well documented.
•Developmental steps have not been validated.
Punting
•The ball is dropped from the hands.
•Punting is more difficult for children than kicking.
Characteristics of Early Punting
•Ball is tossed
up rather than dropped.
•Punter often
contacts ball
with toes rather
than with instep.
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.
An Advanced Punter
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
Developmental Changes in Punting: Legs
Ball-contact phase
•No short step, ankle flexed
•Long step, ankle extended
•Leap and hop
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.
Characteristics of Early Sidearm Striking
•Chopping motion (elbow extension)
•Little leg and trunk movement
Intermediate Striker
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
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)
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.
Overarm Striking
•Without an implement (volleyball serve)
•With an implement (tennis serve)
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
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.
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)
Developmental Changes in Overarm Striking (continued)
Elbow action in ball-contact phase
•Very small or very large angle
•Intermediate angle (2–89 degrees)
•Ideal angle (90–119 degrees)
Spinal and pelvic range of motion
•Less than 45 degrees
•Rotation of 45 to 89 degrees
•Rotation of 90 degrees or more
Developmental Changes in Overarm Striking (continued)
Racket action
•No racket lag
•Racket lag
•Delayed racket lag
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)
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.
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.