Relationships between task-oriented postural control and motor ability in children and adolescents with Down syndrome.

Individuals with Down syndrome (DS) have been characterized by greater postural sway in quiet stance and insufficient motor ability. However, there is a lack of studies to explore the properties of dynamic postural sway, especially under conditions of task-oriented movement. The purpose of this study was to investigate the relationships between task-oriented postural control and motor ability in children and adolescents with DS. The participants were 23 children and adolescents with DS (DS group, M±SD age, 14.4±2.8 years) and 18 age- and gender-matched peers (M±SD age, 13.8±3.6 years). A force plate was used to collect postural data represented by center of pressure (COP) parameters. Postural measurements were conducted for both groups in quiet standing with eyes open and with eyes closed, and also while throwing a ball at erect standing. Assessments of motor ability were only applied to the DS group by using two dimensions of the original version of Gross Motor Function Measure and 4 subtests of the Bruininks Oseretsky Test of Motor Proficiency, second edition. The results showed that while the participants with DS showed greater displacement and higher velocity of COP sways at quiet standing, they exhibited smaller COP displacement in anterior/posterior direction during throwing the ball. Three areas of motor ability, including standing motor skills, walk/run/jump motor skills and muscle strength, were found to make a significant contribution to the displacement and velocity of postural sway during the voluntary movement. It is suggested that future research should focus on investigating the definite underlying mechanism of postural sway during movement and the influence of increasing motor ability on the reactive postural sway in this population.