Relationship Between Muscle Strength and Self-selected Throwing Styles of Young Children: Pre and Post Demonstration of the Mature Pattern

J. Ratanapinunchai1 & P. Silsupadol2

1. Department of Physical Therapy, Faculty of Associates Medical Sciences,
Chiangmai University, Chiang Mai, Thailand

2. Department of Orthopedic, Faculty of Medicine,
Chiangmai University, Chiang Mai, Thailand


The study aimed to determine the relationship between the shoulder muscle strength and self-selected throwing styles of young children before and after demonstration of the mature overarm throwing pattern. Thirty-two healthy boys (2-7 years old) participated in the study. Isometric strength of the external rotator, the internal rotator and the horizontal adductor of the shoulder muscles were measured using a push-pull dynamometer. Subjects were asked to throw a light plastic ball as far as they could from the standing position. No demonstration of the throwing pattern has been introduced to the subjects. The results presented a significant relationship between the isometric strength and the self-selected throwing patterns. Subjects who choose an underarm throw or an immature overarm throw had a lower isometric force, whereas those who had a stronger contraction prefer a mature overarm throw. Younger boys (2-3 years) selected only an underarm or an immature overarm throw. After the demonstration of the mature overarm pattern, some subjects still used an underarm or an immature overarm style. Relationship between muscle strength and the throwing pattern was higher for the internal rotator (rpre = .51, rpost = .57) and horizontal adductor (rpre = .41, rpost = .54) in contrast to a lower coefficient of external rotator (rpre = .57, rpost = .47). The results confirmed the role of shoulder muscle strength on the throwing pattern.