462
M. van Bloemendaal et al.
Whether this is a limitation of the SGAS or of the
reference system is not fully clear, as no study on the
measurement properties of the GAITRite® system has
assessed how valid this system is in assessing double
support time (15, 16, 32, 35–38), and only one study
described swing time, but results on measurement error
were not reported (16). In support of our findings, 2
other studies found moderate levels of agreement
between the GAITRite® system and low-cost, port
able systems for assessing double support time and
swing time (26, 39). Perhaps the low time resolution
of these systems (i.e. 50 Hz) could be an explanation
for these findings, as double support and swing time
are short events in the gait cycle. A camera with a
higher sampling rate (e.g. 100 Hz) could be applied,
but a disadvantage is that the size of the video data will
substantially increase.
The current study has some limitations. The cal-
culated minimum number of footsteps needed to
achieve an adequate level of reliability for the SGAS
data may not be generalizable to individuals with gait
deviations. These individuals often show larger step
variability and may show rotations in the transverse
plane, such as foot inward rotation, which may lead
to inaccuracies in measurements in the sagittal plane.
Future research on this topic should include subjects
with gait deviations and examine more than 10 trials
of footsteps and strides, as recommended by other
studies (16, 40). A second limitation concerned an
error in the experimental set-up, where calibration of
the SGAS was carried out on the floor and not on the
GAITRite® carpet, which is 0.32 cm above the floor.
This error has most likely influenced the differences
found in the spatial parameters between the SGAS and
the GAITRite® system (significant mean differences
for step length of 0.06–1.24 cm). Finally, while data
processing is not considered time-consuming, ef-
ficiency may be improved by automated processing.
For example, in determining initial contact and toe
off, which will also enhance accuracy and feasibility.
In conclusion, the SGAS is a valid and reliable
system for assessing step length, step time, stance
time, stride length, and stride time in different walking
conditions and with both stationary and moving camera
set-up. The validity of the SGAS for the assessment
of double support time and swing time needs further
investigation, preferably using a 3-dimensional gait
analysis system as reference. Moreover, future research
should validate the SGAS in subjects with gait devia-
tions. A minimum of 4 footsteps is recommended for
adequate reliability in each of the parameters tested,
with a stationary camera.
www.medicaljournals.se/jrm
ACKNOWLEDGEMENTS
The contribution of all subjects is gratefully acknowledged. The
authors would like to thank G. E. A. van Bon, MSc, for support
with the GAITRite® system, and M. E. Blankendaal, PT, who
assisted in the data collection. We acknowledge E. J. P. Roek,
M. W. Wojakowski, PT, W. Bout, MSc, B. N. Stevenson, PT,
and R. L. van Halteren, PT, for their support with data analysis.
In particular, we would like to thank H. G. van Bloemendaal,
BSc, for making the software available as open source.
The authors have no conflicts of interest to declare.
REFERENCES
1. Perry J. Gait analysis: normal and pathological function.
1st edn. Thorofare: SLACK Inc.; 1992.
2. Balaban B, Tok F. Gait disturbances in patients with stroke.
PM R 2014; 6: 635–642.
3. Zago M, Condoluci C, Pau M, Galli M. Sex differences in
the gait kinematics of patients with Down syndrome: a
preliminary report. J Rehabil Med 2019; 51: 144–146.
4. Rinne MB, Pasanen ME, Vartiainen MV, Lehto TM, Sarajuuri
JM, Alaranta HT. Motor performance in physically well-
recovered men with traumatic brain injury. J Rehabil Med
2006; 38: 224–229.
5. Guillebastre B, Calmels P, Rougier P. Effects of muscular
deficiency on postural and gait capacities in patients with
Charcot-Marie-Tooth disease. J Rehabil Med 2013; 45:
314–317.
6. Warlop T, Detrembleur C, Bollens B, Stoquart G, Cre-
vecoeur F, Jeanjean A, et al. Temporal organization of
stride duration variability as a marker of gait instability
in Parkinson’s disease. J Rehabil Med 2016; 48: 865–871.
7. Balemans AC, van Wely L, Middelweerd A, van den Noort
J, Becher JG, Dallmeijer AJ. Daily stride rate activity and
heart rate response in children with cerebral palsy. J Re-
habil Med 2014; 46: 45–50.
8. Patterson KK, Nadkarni NK, Black SE, McIlroy WE. Gait
symmetry and velocity differ in their relationship to age.
Gait Posture 2012; 35: 590–594.
9. Xie YJ, Liu EY, Anson ER, Agrawal Y. Age-related imbalance
is associated with slower walking speed: an analysis from
the national health and nutrition examination survey. J
Geriatr Phys Ther 2017; 40: 183–189.
10. Lythgo N, Wilson C, Galea M. Basic gait and symmetry
measures for primary school–aged children and young
adults. II: walking at slow, free and fast speed. Gait Pos-
ture 2011; 33: 29–35.
11. Kraan CM, Tan AH, Cornish KM. The developmental dy-
namics of gait maturation with a focus on spatiotemporal
measures. Gait Posture 2017; 51: 208–217.
12. Youdas JW, Hollman JH. Agreement between the GAITRite
walkway system and a stopwatch-footfall count method
for measurement of temporal and spatial gait parameters.
Arch Phys Med Rehabil 2006; 87: 1648–1652.
13. Eichelberger P, Ferraro M, Minder U, Denton T, Blasimann
A, Krause F, et al. Analysis of accuracy in optical motion
capture – a protocol for laboratory setup evaluation. J
Biomech 2016; 49: 2085–2088.
14. Muro-de-la-Herran A, Garcia-Zapirain B, Mendez-Zorrilla
A. Gait analysis methods: an overview of wearable and
non-wearable systems, highlighting clinical applications.
Sensors 2014; 14: 3362–3394.
15. Webster KE, Wittwer JE, Feller JA. Validity of the GAITRite
walkway system for the measurement of averaged and
individual step parameters of gait. Gait Posture 2005;
22: 317–321.