Does postural stability affect grasping?

We examined whether challenging upright stance influences the execution of a grasping task. Participants reached to grasp a small sphere while standing either on a stable surface or on foam. Before reaching for the sphere, participants exhibited more body sway and greater fluctuations in the centre of pressure when standing on foam. While reaching for the sphere, the overall body posture changed less when standing on foam than when standing on the stable surface. The digits' and wrist's movements towards the sphere were no different when standing on foam than when standing on the stable surface. Presumably, the redundancy in the way movements can be performed is exploited to choose the most suitable changes in joint angles to achieve the desired movements of the digits under the prevailing conditions.

► Subjects executed reach-to-grasp movements when standing either on a stable surface or on a piece of foam. ► Standing on foam increased postural sway. ► Anticipatory postural adjustments depended on the support surface. ► Spatiotemporal grasping characteristics were the same for the two support surfaces.