Coordination of pelvis-HAT (head, arms and trunk) in anterior-posterior and medio-lateral directions during treadmill gait in preadolescents with/without Down syndrome.

In human biped gait, movements in the frontal plane such as side-to-side rocking, are as essential as the alternating movement of the legs in the sagittal plane. In addition, the top-heavy structure of human body necessitates control of the trunk during walking. In this study, we evaluated the pelvis and HAT (head, arms and trunk) movements and their coordination during treadmill walking in the anterior-posterior and medio-lateral directions in children with typical development (TD) and those with Down syndrome (DS). Participants were 12 children with DS aged 8-10 years and 10 age-matched children with TD. They walked on a treadmill at 40%, 75% and 110% of their preferred overground walking speeds. Kinematic data were collected using a 3D-motion-capture system; movements of the mid-point of hip joints (OPELVIS) and the center of mass of HAT (COMHAT) were reduced. Children with DS showed larger and speed dependent amplitude responses compared to their TD peers. Coordination patterns for children with DS were less stable, especially in medio-lateral direction at slow speed. Differences in amplitude response may be the result of poorer trunk control in children with DS or, alternatively, part of a necessary and sufficient propulsion/stabilization mechanism for this population with reduced tone and muscle strength. Response differences observed between the anterior-posterior and medio-lateral directions for both groups may reflect relative differences in the involvement of active neuromuscular control.