Changes in standing postural control during acquisition of a sequential reaching task.

Postural control acquired during learning functional reaching movements has not been well examined. Fourteen healthy adults practiced a serial reaching task 300 times. Task acquisition was examined considering two types of action-goals [1]: hand accuracy and consistency as the focal action-goals and control of equilibrium as the postural action-goal [2,3]. Hand accuracy and consistency were measured as absolute constant error and variable error. Postural control was measured by time to boundary (TtB). Improvements were expected in the focal goals and postural goal; however the timing of improvements might reflect explicit and implicit learning processes. Practice effects resulted in improvements for hand task accuracy, consistency and an increase in TtB values. Changes in postural control may reflect improved efficiency or improved perception-action coupling by the postural system within task performance. Copyright 2009 Elsevier B.V. All rights reserved.