| Sumario: | BACKGROUND: According to the Dynamic Dominance Model (DDM), the dominant (preferred) and non-dominant (non-preferred) upper limbs are specialized for different control mechanisms, which may influence postural regulation during goal-directed manual actions. AIM: To compare postural control during a reaching and grasping task performed in an upright posture with the preferred and non-preferred upper limbs across different movement directions. METHODS: Thirty right-handed participants performed a reaching and grasping task in multiple directions and movement conditions using both upper limbs. Postural control was assessed using a force platform by analyzing the center of pressure (CoP) area, orientation (major elliptical axis), mean velocity, antero-posterior and medial-lateral excursion, and their lateral symmetry indices (LSIs). LSI values were compared to zero using t-tests, and task conditions were analyzed using repeated-measures ANOVA. RESULTS: Traditional CoP measures (area, velocity, and antero-posterior and mediallateral excursion) did not differ across limbs or task conditions (all P-values > 0.065). However, the elliptical major angle revealed significant task- and limb-dependent effects, indicating changes in the directional organization of postural sway. INTERPRETATION: Although upper limb preference did not influence the magnitude of postural sway, it modulated the spatial organization of postural control. Within the DDM, these findings suggest that lateralized control mechanisms may affect coordination strategies rather than global stability. Thus, postural adjustments during upright reaching and grasping appear to be shaped by both task demands and limb-specific organization, even when overall stability is preserved.
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