SUBJECTS AND METHODS
Forty healthy subjects who had no previous history of
neurological, musculo-skeletal or other medical conditions
that could have affected gait were recruited. All the subjects
understood the purpose of this study and gave their written
and informed consent prior to their participation. The study
protocol was approved by the local Institutional Review
Board and complied with the ethical principles of the Declaration
of Helsinki.
The subjects were first asked to walk along a 10 m walkway
at a comfortable pace. The procedure was repeated at
two different gait speeds, performed in a random order, to
give three sequences of data for each subject. The three gait
speeds were as follows and were always performed at a selfselected
speed: slow speed (SS): a gait somewhat slower
than normal walking speed; normal speed (NS): a gait at a
normal, comfortable speed; fast speed (FS): a gait somewhat
faster than normal walking speed13). The experimental order
of the self-selected gait speeds.
A twelve-camera video-based motion analysis system
(Vicon, UK) was used to record joint angles. Sixteen reflecting
markers were placed on specific anatomical landmarks
on the hip (ASISs and PSISs) as well as on each mid-thigh
(the lower lateral 1/3 of the thigh), knee (lateral epicondyle),
mid-tibia (lower 1/3 of the shank and lateral malleolus), and
foot (second metatarsal head and heel) for capturing joint
motion. The marker protocol was based on the Plug-in-gait
marker set. The motion capture rate was 120 fps. Two force
plates (Advanced Mechanical Technology Inc., USA) were
placed at the centre of the 10 m walkway to measure the gait cycle. Data collected from the force plates were digitized at
500 Hz and low-pass filtered at 1,000 Hz. The system was
capable of measuring separate repeated steps over successive
strides for extended trials. Only trials that included three
consecutive clean force platform data and complete data
were considered.
The statistical analysis was performed using SPSS ver.
12.0. Demographic data such as age, height and weight were
analyzed by one-way ANOVA. The values of the different
gait speeds were compared using one-way ANOVA and
least-squares difference as a post hoc test. Statistical significance
was accepted for values of p