Hogeschool van Amsterdam

Urban Vitality

Anticipatory postural adjustments prior to load pick-up in a bi-manual whole body lifting task

Abstract: Balance regulation and movement control were examined in the context of bi-manual lifting. Subjects picked up a load (20% body mass) after several unloaded cycles using the leg-lift technique.

The addition of the load to the body caused the system center of mass to shift forward and thus presented the subject with an expected perturbation of balance. To examine whether the disturbances to balance were counteracted by anticipatory postural adjustments, the last cycle, in which the barbell was grasped and lifted, was compared with the preceding unloaded cycle.

Using a global mechanical analysis of the movement, we found that anticipatory postural adjustments were present before load pickup in bi-manual lifting. These anticipatory postural adjustments were characterized by a backward directed horizontal momentum, a backward directed horizontal component of the ground reaction force accompanied with a forward shift of the center of pressure, and a backward shift of the center of mass (CoM). These characteristics could all be understood from the mechanical consideration that adding a load in front of the body induces a forward shift of the CoM. However, major compensations of the position of the CoM were also observed after bar grasp.

It is therefore proposed that commands giving rise to postural adjustments are closely tied to commands controlling the ongoing movement. On the basis of this insight the strict dichotomy in the control of posture and movement is being questioned.

Link pfd

Referentie

Toussaint, H. M., Commissaris, D. A. C. M., Hoozemans, M. J. M., Ober, M. J., & Beek, P. J. 'Anticipatory postural adjustments prior to load pick-up in a bi-manual whole body lifting task'. Medicine and Science in Sports and Exercise, 29(9), 1208-1215, 1997.

Gepubliceerd door  Kenniscentrum Bewegen, Sport en Voeding 1 september 1997

Publicatiedatum

sep 1997

Auteur(s)

Lector Huub Toussaint