Protocol
Participants were fitted with the accelerometer apparatus and
footwear and were instructed to look directly ahead and to walk
on the irregular walkway and the level corridor at their normal
comfortable walking speed. Two trials of each condition were
performed in a randomized order. Participants walked the full
20m for each trial; however, only the designated 15-m trial
distance was analyzed so as to exclude the first and last 2 to 3
steps.
Walking speed and cadence were not controlled for 3 reasons.
First, although having subjects walk at the same speed
would reveal even greater differences between DPN subjects
and controls, we believe that it is of limited value to test
subjects at walking speeds they rarely use, and that testing
them at their normal speed provides more valid insights into the
mechanisms that may be responsible for imbalance in real-life
situations. Second, controlling for walking speed or cadence by
the use of metronomes or treadmills may lead to gait patterns
that are unrepresentative of normal overground walking. Finally,
we have previously shown that the major gait parameter
derived from the accelerometry signal—the harmonic ratio—is
Fig 1. Testing procedure. Abbreviation: V, vertical.
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