chapter 8 Development of Ballistic Skills

Ballistic Skills Performer applies force to an object in order to project it. Examples include throwing, kicking, striking.

Overarm Throwing Many forms Most common in sport: one-hand overarm Underhand (one- or two-hand) Sidearm Overarm (one- or two-hand) Most common in sport: one-hand overarm

Gauging Throwing Skill Product measures (outcome): accuracy, distance, ball velocity Process measures (movement pattern): developmental sequences

Which Approach to Judging? Why would an instructor use process measures to judge proficiency of throwing? Why would an instructor use product measures to judge proficiency of throwing?

A Beginning Thrower (continued)

A Beginning Thrower (continued)

A Beginning Thrower (continued) Click image to view video

Early Overarm Throwing Mostly arm action Elbow pointed up Throw executed by elbow extension alone

A Proficient Thrower Click to add notes Click image to view video

Proficient Overarm Throwing for Force Thrower uses preparatory windup (weight shifts and trunk rotates back; arm swings). Thrower uses opposite leg, long step, and differentiated trunk rotation. Upper arm and forearm lag. 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 (continued)

Developmental Changes in Overarm Throwing (continued) Foot action No step Homolateral step Short contralateral step Long contralateral step (continued)

Developmental Changes in Overarm Throwing (continued) Upper arm action Oblique Aligned but independent Lagging Forearm action No lag Lag Delayed lag

Progression in Childhood Throwers do not achieve same step for each body component at same time. Some step combinations are observed more frequently than others. Not everyone reaches highest step in each component. Differences are observed between the sexes in throwing skill.

Question: Explain the differences observed between the sexes in throwing (consider the interaction of individual, task, and environmental constraints).

Throwing in Adulthood Older adults demonstrate moderately advanced steps. Differences are observed between the sexes. Ball velocities are moderate. Musculoskeletal constraints might influence movement patterns used. Change is slow, involves decline (and more variability) in performance, and is typically related to control rather than coordination.

Throwing for Accuracy Throwers may use lower developmental steps for accuracy throws than for forceful throws. When required to throw a greater distance, differences between throws are minimal.

Kicking Performer strikes ball with foot. Kicker must have perceptual abilities and eye–foot coordination to make contact (kicking a moving ball is difficult for children).

Characteristics of Early Kicking No step is taken with nonkicking leg. Kicking leg pushes forward. Click to add notes Click image to view video

Intermediate Kicker Click image to view video

Proficient Kicking Preparatory windup is used (trunk is rotated back, kicking leg cocked, knee bent). Trunk rotates forward. Movement is sequential: thigh rotates forward, then lower leg extends. Arms move in opposition to legs.

Proficient Kicker Click image to view video

Developmental Changes in Kicking Movement pattern changes are not well documented. Developmental steps have not been validated.

Question: How might a coach or teacher design developmentally appropriate kicking activities for children at the following levels? Beginning Intermediate Advanced

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

Characteristics of Early Punting Ball is tossed up rather than dropped. Punter often contacts ball with toes rather than instep.

Beginning Punter Click image to view video

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

An Advanced Punter

Advanced Punting Click image to view video

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 Arm drop Arm abduction 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. Principles can be applied to other striking tasks.

Characteristics of Early Sidearm Striking Chopping motion (elbow extension) Little leg and trunk movement Click to add notes Click image to view video

Intermediate Striker Click to add notes Click image to view video

Proficient Sidearm Striking Sideways preparatory stance and long step Differentiated trunk rotation Horizontal swing through large range of motion (arm extended before contact) Sequential movements Click image to view video

Developmental Changes in Sidearm Striking Sequences for foot and trunk in overarm throw can be used. Trend is toward use of trunk rotation (none, then blocked, then differentiated). Plane of swing progresses from vertical to horizontal. (continued)

Developmental Changes in Sidearm Striking (continued) Grip changes from power grip to “shake-hands” grip. Elbows are held away from body and extended before contact.

Overarm Striking Without an implement (e.g., volleyball serve) With an implement (e.g., tennis serve)

Characteristics of Early Overarm Striking Limited trunk rotation Swing with collapsed elbow Little or no lag with swing forward Much like early throwing in appearance

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 those for overarm throwing Preparatory trunk action No trunk rotation 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 Rotation of less than 45 degrees Rotation of 45 to 89 degrees Rotation of 90 degrees or more (continued)

Developmental Changes in Overarm Striking (continued) Racket action 1. No racket lag 2. Racket lag 3. Delayed racket lag

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 than younger golfers for same shot. Most older golfers were just as accurate as younger golfers. (continued)

Older Adult Striking (continued) Haywood & Williams (1995) Studied tennis players’ first serves. Studied older servers at moderate levels. Two former teaching professionals were categorized at the highest levels (i.e., maintained coordination of movements).

Ballistic Skills: Summary Proficient performance demonstrates the mechanical principles. Developmental trends are toward proficient mechanical performance. Performer uses forward step and more trunk rotation. Trunk rotation is differentiated. Projecting limb shows increasing lag. (continued)

Ballistic Skills: Summary (continued) Not all individuals reach highest developmental steps. Older adults appear to maintain coordination of ballistic movements fairly well.

Assessment of Ballistic Skills Developmental sequences can be used as checklists. Individuals are in a developmental step if a majority of executions (usually out of five attempts) fall into that category. Observation should be conducted from the appropriate direction. Side views show forward step, trunk action, lagging. Rear views show arm angles.