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Characteristics of early overarm throwing

This is an excerpt from Life Span Motor Development 8th Edition With HKPropel Access by Kathleen M. Haywood & Nancy Getchell.

Throwing takes many forms. The two-hand underhand throw (with windup between the legs) and the one-hand underhand throw are both common in young children. There is also a sidearm throw and a two-hand overarm throw. The type of throw a person uses, especially among children, often depends on task constraints, in particular the rules of the game or sport including the size of the ball. Our focus, though, is on the one-hand overarm throw, which is the most common type of throw in sport games. Overarm throwing is one of the few fundamental skills universally seen across cultures and geographic regions. It has been studied more widely than other ways of throwing. Many of the mechanical principles involved in the overarm throw apply to other types of throws as well.

Researchers often make product assessments to gauge throwing skill development; that is, they measure the end product, or result, of the throwing movement, such as the accuracy, distance, or ball velocity. However, product measures have several drawbacks. Researchers must often change an accuracy assessment task when working with children of different ages. Young children need a short distance over which to throw to reach a target, but a short distance makes the task too easy for older children, who might all achieve perfect scores. Thus, researchers must either increase the distance or decrease the target size for older groups. In addition, scores on throws for distance often reflect not just throwing skill but also factors such as body size and strength. Two children may have equal throwing skills but quite different distance scores because one child is bigger and stronger. Finally, measuring ball velocity at release requires specialized equipment that may not be readily available. Thus, we could argue that product scores are not as useful to teachers, parents, and coaches as knowing how a child throws. Let us now turn our attention to the quality of the throwing pattern.

Characteristics of Early Overarm Throwing

It is helpful to contrast children’s early attempts to throw with an advanced overarm throw. Young children’s throwing patterns, especially those of children younger than 3, tend to be restricted to arm action alone (Marques-Bruna and Grimshaw, 1997). The child depicted in figure 6.1 does not step into the throw or use much trunk action. This child merely positions the upper arm, often with the elbow up or forward, and executes the throw by elbow extension alone. Figure 6.2 shows more movement but little gain in mechanical efficiency. These children demonstrate minimal throwing skill.

KEY POINT In very young children, throwing consists of arm action alone.

Proficient Overarm Throwing

By studying the characteristics of a proficient throw, we can identify the limitations in early throwing attempts. An advanced, forceful throw for distance involves the following movement patterns:

• The weight shifts to the back foot; the trunk rotates back; and the arm makes a circular, downward backswing for a windup.
• The leg opposite the throwing arm steps forward to increase the distance over which the thrower applies force to the ball and to allow full trunk rotation.
• The trunk rotates forward to add force to the throw. To produce maximal force, trunk rotation is differentiated, which means the lower torso leads the upper torso, which results in a movement that looks like the body opens up.
• The trunk bends laterally, away from the side of the throwing arm.
• The upper arm forms a right angle with the trunk and comes forward just as (or slightly after) the shoulders rotate to a front-facing position. This means that from the side, you can see the upper arm within the outline of the trunk.
• The thrower holds the elbow at a right angle during the forward swing, extending the arm when the shoulders reach the front-facing position. Extending the arm just before release lengthens the radius of the throwing arc.
• The forearm lags behind the trunk and upper arm during the forward swing. While the upper trunk is rotating forward, the forearm and hand appear to be stationary or to move down or back. The forearm lags until the upper trunk and shoulders actually rotate in the direction of the throw (the front-facing position).
• The follow-through dissipates the force of the throw over distance. The greater portion of wrist flexion comes during follow-through, after the thrower releases the ball.
• Dissipating force after release allows maximal speed of movement while the ball is in the hand.
• The thrower carries out the movements of the body segments sequentially, progressively adding the contributions of each part to the force of the throw. In general, the sequence is as follows:

1. Forward step and pelvic rotation
2. Upper spine rotation and upper arm swing
3. Upper arm inward rotation and elbow extension
4. Release
5. Follow-through

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