Course:KIN366/ConceptLibrary/Throwing 2

Movement Experiences for Children
KIN 366
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Instructor:	Dr. Shannon S.D. Bredin
Email:	shannon.bredin@ubc.ca
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Throwing is a movement skill that is defined as the propulsion of an object through the air by the movements of the arm and hand. It is one of the fundamental movement skills that all children should develop between the ages of zero and nine. The development of fundamental movement skills in children are important because they are the building blocks or foundational movements for more complex and specialized skills required for sports and recreational activities (Kids at Play, 2014). Throwing occurs in multiple phases and depending on the maturity of the throw, these phases can vary significantly.

Types of Throwing Patterns

Throwing takes many forms and the form that a person uses, especially among children, often depends on the task constraints, particular rules and the size of the object. The two most common throwing patterns are the overhand throw and the underhand throw.

Overhand Throwing

The overhand throwing pattern is a single-handed throw where the object is thrown from above the shoulders. This throwing pattern requires very complex motor skills that involve the entire body in a series to propel the object forward. By age three, children should have developed the gross motor skills to participate in organized sports and activities that require the overhand throw (Kids at Play, 2014). This movement demands more concentration than other routine activities such as walking and running; therefore it gets developed a little later in a child’s life. The quality of the throw is affected by the physical attributes of the child such as height, strength, and flexibility. However it is mainly the thrower’s mechanics that largely determine the quality of the throw (Parenting Counts, 2014). If the child has developed proper throwing maturity, taking a stride towards the target with the leg opposite to the throwing arm before the release of the object enhances the overhand throw. This forward step, commonly known as the stride step, allows more energy to be produced that transfers up to the body. The stride step should be performed while raising the throwing arm above the shoulders to maximum external shoulder rotation. At this point, the arm is considered to be “fully cocked” (Parenting Counts, 2014). The release and follow-through of the arm depends on the distance and position of the target. This throwing pattern is very similar to the straight sidearm throw, but it is thrown from above the shoulders for greater range of motion. The overhand throwing pattern is the most common type of throw in sport games, some include baseball, football, water polo, dodgeball and javelin (Parenting Counts, 2014).

Underhand Throwing

The underhand throwing pattern is a single-handed throw where the object is thrown from below the waist. This type of throwing pattern also requires complex motor skills in order for proper throwing techniques (Kids at Play, 2014). Children normally use this throwing pattern to launch objects up in the air. It could also be done with both hands if the object is too large to grasp in one hand. The movement sequence for the underhand throw starts off with facing the target. With your dominant hand, grasp the object with your palms up and thumbs outside (Physical and Health Education of Canada, 2014). The cocking phase is just like the overhand throw but instead of maximum external rotation of the shoulders, it is maximum extension at the shoulder joint. At the time of drawback, the thrower takes a stride step forward with the foot opposite to the throwing arm towards the target while swinging the throwing arm forward from below the waist. The point of release depends on where the target is. Releasing the object at waist level would lead to the object propelling forward and the later you release the object, the more vertical the object will be propelled. Although the underhand throwing pattern is not as popular as the overhand throw, it is still used quite frequently in sports and activities. Some of these sports/activities include bowling, softball, volleyball and tennis.

Phases of Throwing

Throwing an object comprises four phases: the preparation phase, the force production phase, the critical instant phase, and the follow-through phase.

Preparation/Wind-up Phase

The first stage of the throwing motion starts at the initiation of the wind-up and ends when the shoulder has reached its maximum external rotation. The entire motion of throwing takes approximately two seconds to complete, and the preparation phase consumes almost 1.5 seconds of the total time (Parenting Counts, 2014). It is the beginning of the throwing motion that prepares the body for the act of throwing. The motion starts in the lower extremities and torso where the vast majority of the power to throw is generated. The arm is brought back in preparation for the throw. Depending on the development of the child and the maturity of the throwing quality, this phase can vary widely. When children first start learning how to throw, most of them don’t even take a stride step in their preparation phase (Parenting Counts, 2014). As the child develops proper throwing technique, contralateral stride step should be performed. Children in the earlier stages often prepare to throw an object by running towards the target. One of the common difficulties for young children when running is swinging their arms across the midline. Either there is absolutely no arm swing at all, or an over exaggerated arm swing, which leads to the rotation of the trunk. These factors in the preparatory phase would ultimately alter the quality of the throw.

The goals in this phase are:

To give some momentum to the projectile before the start of the force production phase
To put the body in a position that will allow maximum range of motion for the projectile
To provide most of the momentum for the thrower and the projectile system

Force Production

This phase begins at the point of maximum external rotation of the throwing shoulder and ends when the object is released. This phase is extremely quick lasting an average of only 50 msec. The distance of the object that is propelled depends on the amount of force that is exerted. The more developed the child is at throwing, the better he/she is at transferring the potential energy from the lower extremities to the upper extremities where it is then transformed into kinetic energy as the projectile is released (Physical Therapy & Sport Medicine Institute, 2013). Strength is a very important aspect in this phase. If the child does not have sufficient upper body strength, the object will not be propelled to the desired distance. The movement of the legs provides additional momentum for the thrower. More specifically, the legs need to move the shoulders of the throwing arm in the direction of the throw. This provides maximum range of motion for the projectile and aids the arm muscles to produce a larger force. The body is brought forward while the arm follows behind so that the energy developed by the body’s forward motion can be transferred to the throwing arm. The primary goal in this phase is to exert a large force on the object over a long range of motion to maximize the distance of the throw.

Instant of Release

This phase is defined as the instant when the object leaves the hand. Where the object is released depends on the distance of the thrower’s target. The farther the target is, the higher the release point so that you can get some vertical translation as well as horizontal. When holding objects that are too big for the child to grasp comfortably, the instance of release can be unpredictable.

Follow-through

The follow-through is the final phase in throwing. This phase slows down all body motions and stops the forward movement of the body and the muscle activity returns to its resting state. If this phase is completed correctly, the thrower’s body position is “under control” and balanced. For children that have just learnt to stand or walk, their balance and coordination are not fully developed yet. Therefore, the inability to control the follow-through and the deceleration of the throwing arm may lead to them falling down. It is very important for children with poor balance to be very careful with the deceleration of the throw because this rapid deceleration is actually the most violent part of the entire throwing motion. The greatest amount of joint loading occurs at this stage.

Five Stages of Maturity for Throwing

The maturity of a child’s throwing ability occurs in a progression and these progressions can be explained by five stages. The quality of the throw depends on many factors such as the size of the child’s hand, the size, shape and weight of the object, and the biomechanics of the thrower. Because throwing is a fundamental movement skill, it is imperative that all children learn and perfect proper throwing technique (Physical Therapy & Sport Medicine Institute, 2013).