Head Motion in Overarm Throwing for Children with Varying Levels of Motor Proficiency

The overarm throw has been classified as a fundamental motor skill that is the basis for a number of more complex sporting skills. There arc a number of developmental stages over which a child progresses to the mature form of the skill. Control of the ovcrann throw, especially towards a target is very dependent on visual and vestibular infonmttion for successful execution. The quality of the infonnation is, in tum, dependant on the head movement of the perfonner during the execution of the skill. It has been reported that head angular velocities above 350 degrees/second result in a degradation of useful visual and vestibular infonnation and as such, a loss in control of the perfonned skill. The purpose of this study was to investigate head movement in children while they performed an overann throw towards a forward facing target. The study also investigated the possible relationship bet\veen motor proficiency of the thrower and their head movement. Three hypotheses were itivestigated. These included: 1. The head is stabilised during the throw. 2. The head is stabilised throughout the performance until close to ball release where it will move with the trunk as part of the 'kinetic chain'. 3. Subjects with lower levels of motor proficiency stabilise their head Jess over the whole perfonnance when they are compared to subjects with higher motor proficiency levels. Ten, ten-year-old children of mixed gender and varying levels of motor proficiency participated in the study. Subjects were video recorded performing an overarm throw towards a forward facing target. Their throwing proficiency was assessed using a standard motor test. The video of the throw was digitised and analysed to produce angular velocities profiles of the head and trunk about different reference axes. It was found that all of the subjects except one stabilised their head throughout the whole throwing perfonnance. It was also found that the subjects ii stabilised their head intentionally and indeprmdently despite large trunk angular velocities near the end of the performance. These findings support hypotheses l and 2. No signiricant relationship was fOund between motor proficiency and head movement. Thus hypothesis 3 remained unsupported. Further research with a larger sample s1ze and changes to the motor proficiency-testing regime are required to investigate the possible relationship between motor proficiency and head movement.