Article

Many falls in older adults occur during walking following trips. Following a
trip, older adults take longer than younger adults to recover steady-state
walking. Although faster gait speed may improve interlimb coordination, it may
also increase fall risk in older adults. We hypothesized that older adults would
take longer than younger adults to recover from an unexpected perturbation during
gait especially when walking faster. Twelve younger (26.3 +/- 4.4 years) and 12
older adults (68.5 +/- 3.4 years) walked at comfortable, faster and slower speeds
when movement of the dominant leg was unexpectedly arrested for 250 ms at 20%
swing length. Gait stability was evaluated using the short- and longer-term
response to perturbation. In both groups, walking faster diminished the
occurrence of elevation and increased that of leg lowering. Older adults took
longer than younger adults to recover steady-state walking at all speeds (3.36
+/- 0.11 vs. 2.89 +/- 0.08 strides) but longer-term recovery of gait stability
was not related to gait speed. Arm-leg and inter-arm coordination improved with
increasing gait speed in both groups, but older adults had weaker inter-leg
coupling following perturbation at all speeds. Although both younger and older
adults used speed appropriate responses immediately following perturbation,
longer duration of recovery of steady-state walking in older adults may increase
fall risk in uncontrolled situations, regardless of gait speed. Recovery from
perturbation when walking faster was associated with better interlimb
coordination, but not with better gait stability. This indicates that interlimb
coordination and gait stability may be distinct features of locomotion.
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Langue : ANGLAIS