Background: Gait analysis is useful in the assessment of Parkinson’s disease patients since Freezing
of Gait (FOG) is a key feature of the condition and a major cause of disability. FOG can be most
frequently observed in turning. Unfortunately, many studies around FOG and turning are done using a
ground reaction force plate (GRF) which limits the analysis of the movement for different reasons like
having the need to place one entire foot in the plate etc. Therefore, there is a clinical need for the
implementation/validation of an efficient method to analyze turning and FOG in a gait laboratory
without a GRF. By first establishing an efficient methodology to study turning in healthy (young and
elder) volunteers in a gait laboratory, we’ll be able to better understand how to analyze turning by
obtaining spatiotemporal parameters, to determine the main differences between young and elderly
people during turning and to determine differences regarding spatiotemporal parameters while turning
at 90°, 180° and 360°. This study will contribute to a better methodology for analyzing turning in
patients with Parkinson's disease.
Methods: Ten young healthy participants between the ages of 20 to 30 years and 10 elderly healthy
(ON) participants between the ages of 60-85 were recruited. The aim of the experiment was to record
nine correct turns at each given angle of 90°, 180°and 360° in both directions (left and right) as well as
three at 0° in the elderly participant and the same but at two different walking speeds for the young
participants, one normal (YN) and the other slow walking speed (YS). 15 VICON infrared motion
analysis system (120 Hz) cameras and 12 infrared reflection markers (IRMS) were placed upon
anatomical landmarks to obtain spatiotemporal information. The gait events named as heel contacts
and toe-offs were defined using an algorithm validated by Zeni and colleagues in 2008 to obtain all
gait parameters. Two video cameras were placed in the room to observe and to identify turns.
Results: Young people (YN) walk faster when turning 90° and 180°. With higher (360°) turning
angles both groups will walk at the same speed, but the young group will spend less time in the turn
and use fewer steps by employing sharper turns extending their step length and taking wider steps
indicating sharper turns with wider steps. The only coefficient of variation (CV) difference between
YN vs elderly (ON) is Cadence and it could indicate that Cadence varies more between elderly people.
To obtain the same walking speed as an older population while turning, by asking them to walk
slower, young people will tend to have similar spatial parameters taking almost the same space to turn
but modify their temporal parameters. Young people walking slow (YS) will have slower and longerlasting
strides, take longer stance durations, take fewer steps per minute and have sharper turns by
taking wider steps while turning. It is shown here that, differences between these groups are regardless
of their difference in speed and therefore it is not accurate to say that these groups can imitate their
walk by walking at the same speed. In short, young subjects slow down rather than shorting their steps
when imitating elderly gait.
We found almost no significant differences in variability (coefficient of variation; CV) except for step
cadence which was higher in the ON group, between the young and the elderly. These results suggest
that the gait cycle does not change with aging.
Conclusions: this study suggests a feasibility of Not using a GRF plate for turning in PD patients
with FOG vs Non-FOG which would be very beneficial to obtain more temporal parameters such as
Stride duration of internal leg (s), Stride duration of external leg (s), Stance duration of internal leg (s),
Stance duration of external leg (s) and extend the range of recording offering more flexibility for
patients to turn more “freely” without restriction of a GRF plate.
Current literature gives an idea of where differences young and old population come from when it
comes to straight walking. In 2004, Shkuratova et al, published a paper indicating that, when straight
walking, these spatio-temporal differences where even more significantly different when balance was
perturbed by requiring subjects to change from walking at preferred to fast speeds3 and, thanks to Patla
AE et al in 1989, we know that balance can become increasingly difficult with age4 .We conclude from
our study and the studies given with straight gait that balance could be the primary factor responsible
for these changes in spatio-temporal parameters between young and old participants. Also, we may
associate balance disruption with the loss of muscle strength and muscle mass in older people34. We
suggest testing balance and analyze strength in the muscle using a cyber press leg dynamometer or an
ENMG in future studies regarding gait and turning in order to assess whether these modifications are
associated with major falling problems in elderly people while turning.
Significant differences were observed with young participants walking slowly in order to approximate
the gait of an elderly population, suggesting that these differences may be regardless of their walking
speed. Indeed, simulating “elderly gait” is challenging and slowing alone does not define gait in
elderly. It would be rather a combination of spatial and temporal parameters as well as balance
difference that make this speed differences occur.