Shared memory representations for programming of lifting movements and associated whole body postural adjustments in humans

This study examined whether the same memory representation is used for the parametric control of precision lifting and associated postural adjustments (APAs). Fifteen adults lifted object of different weights between the thumb and index finger. The employed grip, load (vertical lifting) forces, and ground reaction forces were recorded and the centre of pressure (COP) displacement as well as the corresponding first time derivatives were calculated. A highly significant correlation was found between the maximum rates of the load force, grip force and COP displacement rate. Different loads also influenced the onset of the COP displacement. The results corroborate the idea that the same memory representations which are used to control the manipulative lifting movement also control the APAs. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.