Article

The purposes of this study were to determine if healthy older adults adopt
strategies to decrease the likelihood of obstacle contact, and to determine how
these strategies are modified as a function of advancing age. Three age groups
were examined: 20-25 yo (N = 19), 65-79 yo (N = 11), and 80-91 yo (N = 18).
Participants stepped over a stationary, visible obstacle on a walkway. Step
length and gait speed progressively decreased with advancing age; the shorter
step length resulted in closer foot placement to the obstacle and an associated
increased risk of obstacle contact. Lead (first limb to cross the obstacle) and
trail (second) limb trajectories were examined for behavior that mitigated the
risk of contact. (1) Consistent trail foot placement before the obstacle across
all ages allowed space and time for the trail foot to clear the obstacle. (2) To
avoid lead limb contact due to closer foot placement before and after the
obstacle, the lead toe was raised more vertically after toe-off, and then the
foot was extended beyond the landing position (termed lead overshoot) and
retracted backwards to achieve the shortened step length. Lead overshoot
progressively increased with advancing age. (3) Head angle was progressively
lower with advancing age, an apparent attempt to gather more visual information
during approach. Overall, a series of proactive strategies were adopted to
mitigate risk of contact. However, the larger, more abrupt movements associated
with a more vertical foot trajectory and lead overshoot may compromise whole body
balance, indicating a possible trade-off between risk of contact and stability.
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Langue : ANGLAIS