Article

The objective of the study was to assess functional postural responses by
analyzing the center-of-pressure trajectories resulting from perturbations
delivered in multiple directions to elderly fallers. Ten elderly individuals were
standing quietly on two force platforms while an apparatus delivered controlled
perturbations at the level of pelvis in eight directions: 'forward (FW)' and
'backward (BW)' [anterioposterior plane (AP)], 'left (LT)' and 'right (RT)'
[mediolateral plane (ML)] and four combinations of these principal directions:
forward-left (FL), forward-right (FR), backward-left (BL) and backward-right
(BR). Perturbations were repeated randomly four times in each direction. Peak
amplitude responses (PAR AP and PAR ML) and times to reach peak amplitude
responses (TPAR-AP and TPAR-ML) were extracted for each perturbation direction
from acquired center-of-pressure data. One-way analysis of variance was used to
test differences between directionally-similar perturbation directions. Balance
abilities were assessed by means of Berg Balance Scale. Average Berg Balance
Scale for the group resulted in 33.9+/-5.8 points, which means that the
participants were at greater risk of fall. The comparison of the group averaged
PARAP and TPAR-AP in all 'forward' directions (FW, FL, FR) as well in all
'backward' directions (BW, BL, BR) have not shown statistically significant
differences. The comparison of the group averaged PARML and TPAR-ML in all 'left'
directions (LT, FL, BL) as well in all 'right' directions (RT, FR, BR) have not
shown statistically significant differences. These results suggest that a
principle of decoupled control may to a large extent be preserved also in elderly
with clearly diminished balancing abilities, which implies that the accuracy in
the assessment of perturbation direction may be well preserved also in very old
age.

Langue : ANGLAIS