Parent handling of typical infants varies segmentally across development of postural control.

Although trunk muscles extend across multiple vertebral joints, recent motor control studies have shown that a top-down progression of trunk control in typical infants occurs incrementally, one segment at a time, until independent sitting. The current study merges this surprising developmental pattern with parent behavior by exploring the relationship between how parents hold their infant and the segmental level for which the infant exhibits postural control. We measured trunk control of 60 infants (1-8 months) via the segmental assessment of trunk control.

Segmental trunk and head dynamics during frontal plane tilt stimuli in healthy sitting adults.

A more detailed understanding of trunk behavior during upright sitting is needed to create a foundation to address functional posture impairments. Therefore, we characterized the dynamics of the trunk and head during perturbed sitting. A three-link inverted pendulum model of head and trunk segments was used to analyze kinematics of eight healthy sitting adults.