Article

The ability to manipulate objects deteriorates with increasing age. In the
coordination of fingertip forces underlying object manipulation, older adults use
excessive grip (normal) forces but maintain anticipatory force control during
simple manipulations. Daily activities are often more complex and involve grasp
manipulations while simultaneously performing other activities. When walking
while carrying an object, young adults couple grip forces to gait-induced
inertial force changes (anticipatory control). It is unclear if anticipatory
control is preserved in older adults during demanding tasks. The purpose of this
study was therefore to investigate aging effects on grasp control when walking
and transporting an object. We included gait perturbations to vary task
difficulty and step regularity associated with walking.
Twelve healthy older
(65-84 years) and young (20-30 years) adults transported a hand-held object
during unperturbed walking, obstacle crossing and step-length changes. While
older subjects employed higher grip-inertial force ratios, they showed a strong
force coupling comparable to that of the young during unperturbed walking and
step-length changes. During obstacle crossing the forces in the older group were
less tightly coupled (grip force delays). Gait patterns were similar between
groups. Our findings indicate that older adults maintain anticipatory control
during regular and irregular walking. Grasp control changes in older adults only
during obstacle crossing suggest that overall task demands (balance requirements,
attention demands) may contribute to declines of manual dexterity in functional
tasks. This highlights the need to investigate grasp control within complex tasks
when aiming to understand impairments of older adults encountered in daily life.
CI - Copyright (c) 2011 Elsevier B.V. All rights reserved.

Langue : ANGLAIS