Article

The present study introduces four event detection algorithms for defining
touch-down and foot-off during stair descent and stair ascent using segmental
kinematics. For stair descent, vertical velocity minima of the whole body
center-of-mass was used to define touch-down, and foot-off was defined as the
instant of trail limb peak knee flexion. For stair ascent, vertical velocity
local minima of the lead-limb toe was used to define touch-down, and foot-off was
defined as the local maxima in vertical displacement between the toe and pelvis.
The performance of these algorithms was determined as the agreement in timings of
kinematically derived events to those defined kinetically (ground reaction
forces). Data were recorded while 17 young and 15 older adults completed stair
descent and ascent trials over a four-step instrumented staircase. Trials were
repeated for three stair riser height conditions (85 mm, 170 mm, and 255 mm).
Kinematically derived touch-down and foot-off events showed good agreement (small
95% limits of agreement) with kinetically derived events for both young and older
adults, across all riser heights, and for both ascent and descent. In addition,
agreement metrics were better than those returned using existing kinematically
derived event detection algorithms developed for overground gait. These results
indicate that touch-down and foot-off during stair ascent and descent of
non-instrumented staircases can be determined with acceptable precision using
segmental kinematic data.
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Langue : ANGLAIS