Both heading and pointing tasks may affect head and trunk since head rotation contributes to orient the gaze and trunk rotation participates to arm movement. The aim of the present study is to evaluate head and trunk 3D orientation during heading and pointing tasks.

Right arm pointing and heading tasks toward eight visual targets placed in a wide frontal workspace were studied in ten healthy, right handed subjects. Three-dimensional orientation of the head and trunk (flexion-extension, lateral bending and axial rotation) and upper arm were measured using an electromagnetic tracking system.

For both heading and pointing tasks, the orientation of the head in space was closely related to the target with a coupling between rotation and contralateral bending. The trunk was stable during heading but showed large leftward axial rotation during pointing as a function of target direction, coupled with right head rotation relative to the trunk.

Our results suggest that the global rotations within the cervical spine compensated for trunk rotation in order to maintain an adapted orientation of the head toward the visual target. In the future, this should be taken into account for the prevention and the rehabilitation of musculoskeletal disorders.