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Work 70 (2021) 1177–1185
DOI:10.3233/WOR-205123
IOS Press
1177
Ergonomic design and evaluation of a
novel laptop desk for wheelchair users
Bita B. Naeinia, Farhad Tabatabai Ghomshehb, Razieh Divanic, Mojtaba K. Daneshc
and Ehsan Garosid,∗
aDepartment of Ergonomics, University of Social Welfare and Rehabilitation Sciences, Teheran, Iran
bPediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences,
Tehran, Iran
cDepartment of Occupational Health Engineering, School of Public Health, Tehran University of Medical
Sciences, Teheran, Iran
dDepartment of Ergonomics, School of Public Health, Iran University of Medical Sciences, Teheran, Iran
Received 12 September 2020
Accepted 17 May 2021
Abstract.
BACKGROUND: Nowadays, although using laptops to perform many routine activities is inevitable, many wheelchair users
are not able to efficiently use their laptops due to their movement limitations and inappropriate workstations.
OBJECTIVE: The purpose of this study was to design and evaluate a novel ergonomic laptop desk for wheelchair users by
considering their movement limitations.
METHODS: In this experimental study, we ergonomically designed and assessed a novel laptop desk in two phases in a
laboratory. In the first phase of the study, design specifications were identified by an expert panel; accordingly, a new laptop
desk was designed and prototyped for the wheelchair users. In the second phase, in order to evaluate the laptop desk, 14
wheelchair users were asked to complete a typing task within 20 minutes, both with and without using the laptop desk.
Postural risk level, perceived discomfort, and task performance were evaluated using the Rapid Upper Limb Assessment
(RULA) technique, Local Perceived Discomfort (LPD) questionnaire, and the number of letters typed and typing errors,
respectively.
RESULTS: The postures of the wrist, arm, and neck regions were corrected from RULA action level 3 to 2 when the designed
laptop desk was used. In addition, the average perceived discomfort of the participants significantly decreased in the neck,
shoulder, and wrist regions. Furthermore, typing accuracy was improved significantly when novel laptop desk was used.
CONCLUSIONS: Accommodating wheelchair user’s workstation with the novel designed laptop desk could reduce mus-
culoskeletal disorders risk factors and help wheelchair users to perform their work more efficiently.
Keywords: Wheelchairs, laptop desk, ergonomic design
1. Introduction
People should have equal rights to use education
systems and employment opportunities, and to partic-
ipate in all social, creative, or recreational activities,
∗Address for correspondence: Ehsan Garosi, Department of
Ergonomics, School of Public Health, Iran University of Med-
ical Sciences, PO Box 14665-354, Tehran, Iran. E-mail:
eh.garosi@gmail.com.
yet many particular services are designed exclusively
for non-disabled people [1]. Although many assistive
devices (i.e., wheelchair) are designed to allow users
enough personal independence to be able to move
and even return to work, it has not been enough, and
it is estimated that barely 25% of individuals with
mobility impairments are employed in their work-
ing age [2, 3]. Additionally, it is shown that many
wheelchair users experience a lower quality of life
ISSN 1051-9815/$35.00 © 2021 – IOS Press. All rights reserved.
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1178 B.B. Naeini et al. / Design and ergonomic evaluation of a laptop desk
due to functional limitations of their workstation
design [4].
There are many factors that exacerbate occupa-
tional problems of wheelchair users, many of which
are associated with performing tasks by using a
computer or laptop [5, 6]. Zolna et al. showed that
poor workstation design and inappropriate workplace
accommodation as a concern raised by wheelchair
users [4]. While performing computer tasks, the
workers’ arms may outstretch, the wrists can diverge
from neutral position, and repetitive movements may
lead to many adversities including fatigue, pain, phys-
ical weakness, and inability to work for long periods
[7, 8]. Additionally, performance may be negatively
affected [9–12].
Nowadays, electronic devices are an inseparable
part of people’s lives at home and workplaces [13].
Interestingly, studies have shown that wheelchair
users are more interested in using such devices espe-
cially laptops and personal computers since these
devices can have a positive impact on their quality
of work and life [14, 15]. In this regard, results of
previous studies have shown that having the right
equipment, such as laptop and wheelchair, helps
people with lower limb disabilities to cope with chal-
lenges of their environment more efficiently [16].
The progress of technology does not come without
concerns [17, 18]. Hence, Despite the beneficial role
of laptops and other types of equipment in support-
ing wheelchair users, using them in awkward postures
can lead to adverse outcomes [19]. Literature shows
that the static and inappropriate posture of wheelchair
users can lead to development of musculoskeletal dis-
orders [20, 21]. Hough et al., reported that students,
who used their laptop in an inappropriate posture
without putting it on a desk, had musculoskeletal dis-
comfort in their neck, hands, arms, and wrists [22].
Moreover, it is shown that inappropriate interaction
between wheelchair users and their work layout not
only affects their health but also can reduce produc-
tivity and increase human error [23].
Studies argue that common wheelchairs lack the
appropriate design for properly accommodating the
needs of wheelchair users [24, 25]. To address this
issue, there is growing evidence that implementing
ergonomic principles in designing wheelchairs can
minimize risk factors for musculoskeletal disorders,
resulting in improved performance and satisfaction
[26, 27]. Therefore, it is conceivable that one practi-
cal way to solve design issues is to ergonomically
enhance wheelchairs, e.g., by adding accessories
[28].
Accordingly, many wheelchair users need proper
accommodation in their workstation while perform-
ing computer tasks. Given the necessity of ergo-
nomic interventions for implementing necessary
work improvements to such work, this study aimed
to design and evaluate a novel laptop desk for
wheelchair users. It is hypothesized that the new pro-
totyped wheelchair desk will improve users’ working
posture, comfort and functional performance.
2. Method
The present experimental study was approved
by the Ethics Committee and Research Council at
the University of Social Welfare and Rehabilita-
tion Sciences in Tehran, Iran (reference number:
IR.USWR.REC.1395.343). It was conducted in two
phases. The first phase involved introductory, brain-
storming and conceptualization sessions with an
expert panel to explore ideal design requirements
by considering ergonomic principles. Additionally,
a few sessions were held solely with an industrial
engineering team to turn the requirements into con-
crete design specifications and subsequently produce
a prototype. Finally, the second phase of the study was
aimed for ergonomic evaluation of the laptop desk
during a simulated typing task, whose purpose was
to investigate the effects of using the new furniture
on posture and performance of participants.
2.1. Phase one
2.1.1. Expert panel
The aim of the expert panel was to identify both
general and ergonomic design requirements. The
panel included two ergonomics specialists with 5
years of field experience and teaching experience, two
industrial designers with 10 years of work experience,
and three wheelchair users who had been wheelchairs
for the last 5 years.
The first session was an introduction meeting, dur-
ing which people introduced themselves and the topic
of interest (including the background, necessity and
goals of the research) was presented to them in form
of a visual presentation. The experts also were asked
to share any relevant experience or knowledge regard-
ing the topic.
The second session served as a brainstorming ses-
sion during which a package containing catalogs of
various types of wheelchairs and laptop desks avail-
able in the market was prepared and distributed to the
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B.B. Naeini et al. / Design and ergonomic evaluation of a laptop desk 1179
Fig. 1. The laptop desk sketch, A: 2-dimensional view, B: 3-dimensional rendering view.
panel. Then, a brainstorming process took place, dur-
ing which experts’ opinions regarding using a laptop
desk on a wheelchair were collected on sticky notes.
At the end of the session, general requirements (i.e.,
shape, size and function) of a new laptop desk instal-
lable on a variety of wheelchairs were approved by
the panel members.
In the third session, in order to achieve the ideal
conceptual design, various ergonomic requirements
including safety, weight of laptop desk, wheelchair
dimensions, viewing angle, viewing distance of the
laptop screen, hand reaching zone, and convenient
installation were specified by the panel of experts.
2.1.2. Identifying design specifications
After identifying the requirements, appropriate
solutions were determined by the help of the indus-
trial design team. These solutions included the
inclusion of an installable base for the laptop desk
which could be fixed on wheelchair handles in such
a way that it does not interfere with the propulsion of
the wheelchair (as a safety factor). In order to reduce
the weight of the laptop desk, any accessories or
unnecessary parts were removed, and a hollow struc-
ture was introduced into its design (weight factor).
To design a laptop desk that was dimensionally fit
to wheelchairs, relevant wheelchair dimensions were
considered for the laptop desk size (dimension fac-
tor). Dimensions were measured by researchers with
a measuring tape from a conventional wheelchair,
which included the handle length and the distance
between them (520 and 560 mm, respectively). To
adjust the viewing angle, the base part No.3 in Fig. 1
was designed to be movable in Y-axis (viewing angle
factor). In addition, the air outlet grooves and the
Fig. 2. The conventional wheelchair with the designed laptop desk.
place of the teacup and pen were included to provide
comfort and convenience. Convenient installation
and the hand reaching zone (for simultaneous adjust-
ing of viewing angle and hand reach distance) were
not considered in the prototype fabrication. These
items could be part of the final design that may
be accomplished after a summative and ergonomic
assessment of the prototype in the near future. Based
on the specifications mentioned above, Fig. 2 shows
the basic sketch of 2D and 3D rendering of the laptop
desk drawn by Catia v5-6 R2016 software.
2.1.3. Prototyping
After drawing the 3D map, the components of the
prototype were separately made with Plexiglas mate-
rial with a thickness of 10 mm. The horizontal angle
of the laptop desk could be modified between 0 and
30 degrees from the joint (part No. 5). The weight
of the prototype was 2 kg and its dimensions were
600 ×550 ×15 mm. A tray (part No. 2) was designed
for placing a laptop, and a block (part No. 4) was
added to stop laptops from slipping over the tray.
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Additionally, an option was designed (Fig. 1 part
No.3) to adjust the viewing angle. Finally, the pro-
totype was fixed to the armrests by attaching sides
beneath the base (part No. 1). Figure 2 shows the pro-
totype of the laptop desk while fixed to a wheelchair.
2.2. Phase two
2.2.1. Ergonomic evaluation of the prototype
laptop desk
In the second phase, ergonomic evaluation of the
laptop desk was performed in the ergonomics lab-
oratory of the University of Social Welfare and
Rehabilitation Sciences in Tehran, Iran. During the
experiment, the participants were asked to perform
a typing task in two conditions with and with-
out the use of the prototype while being assessed
by the researchers. For the ergonomic evaluation
of the typing task, three evaluation methods were
used. Posture and local discomfort were assessed by
RULA technique and Local Perceived Discomfort
scale, respectively. The former is an observational
method, while the latter is a subjective self-rating
measure. Finally, the performance of the participants
was assessed by counting the number of typed words
and typing errors.
2.2.2. Participants
The study participants were wheelchair users who
had referred to the Rehabilitation Center Clinic at the
University of Social Welfare and Rehabilitation Sci-
ences and used to move by a wheelchair. To recruit
participants the homogeneous sampling method was
used [29]. A poster reflecting the procedure of the
study, inclusion criteria, and contact information was
installed in different areas of the clinic, and peo-
ple were asked to send their information via email
or a phone call if they met the study criteria. The
inclusion criteria were: mobility impairments (being
a wheelchair user), psychological and mental health,
having no infectious diseases or musculoskeletal dis-
orders in the upper limbs (examined by a medical
record at the clinic), having an average typing speed
(in Persian language).
Out of 27 contacts, 20 fulfilled the study cri-
teria. To eliminate bias and have a homogeneous
sample, the typing speed of individuals was inves-
tigated in a pilot study, through which 6 participants,
whose typing speed diverged significantly from 20
words per minutes, were excluded from the study.
Finally, 14 wheelchair users were selected as the
study participants, out of whom nine were female.
The participants’ demographic information were also
collected (mean and SD age: 33 ±5.5 years, weight:
56 kg ±9.7).
Participants had used wheelchairs for at least 3
years, and all of them were right-handed. The major-
ity of participants suffered from paraplegia due to
injury at the lumbar level L1–L4 vertebrae, while
2 of them had to use wheelchairs due to Multiple
sclerosis (MS) condition. It was not possible to cor-
rectly measure the stature of the participants due to
deformity.
2.2.3. Study procedure
After phone call coordination, the participants
were invited to the laboratory, and the procedure
of the study was explained to them. Then, with
the help of the research team members, the partic-
ipants sat in a wheelchair with a randomly assigned
condition (with or without the laptop desk). While
sitting in the wheelchair, the participants were asked
to complete the typing task. The typing text was
selected from a typical Persian storybook. This text
was shown in the split view of a 15-inch laptop
display with a font size of 14 in Microsoft Word soft-
ware. The task completion time was 20 minutes. For
each participant, viewing angle was adjusted by the
researchers according to the optimal screen height for
the wheelchair user (5 cm below the eye level) [25].
In the condition of not using the laptop desk, the
participants placed the laptop either on their knees
or leaned it on the wheelchair handle based on their
preferences. Participants were instructed to perform
the task at their own pace. On Windows timer, the start
and end of the task were fixed and an alarm sounded
when the task time was up. There was a 20-minute
break between the conditions.
2.2.4. Rapid upper limb assessment technique
The posture was assessed by using the RULA
technique. The assessment was simultaneously per-
formed by two ergonomic specialists for each side of
the body. This evaluation was completed for all 14
participants, and finally, according to the RULA final
score, the results for the worst posture were reported
[30].
2.2.5. Local perceived discomfort
Local Perceived Discomfort Scale (LPD) is a sub-
jective method to report discomfort in the major body
regions. An upper limb body map, consisting of five
regions of the body, was presented to the participants.
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Table 1
Results of posture evaluation for each side of the body during the typing tasks
Typing conditions Body side Score A Score B Score C Score D Final score Action level
Without laptop desk Right 3 3 5 4 5 3
Left 3 3 5 4 5 3
Using laptop desk Right 1 2 3 3 3 2
Left 1 2 3 3 3 2
Fig. 3. Illustration of the typing conditions, A: without laptop desk, B: using laptop desk.
They were asked to rate their perceived discomfort in
the neck, trunk, shoulder, wrist, and fingers on a 10-
point scale (ranging from 0, no discomfort; to 10,
extreme discomfort) [31]. The participants reported
their discomfort immediately after finishing the test
in both study conditions
2.2.6. Performance assessment
To evaluate the performance of the typing task,
the error rate (typographical errors) and the number
of typed words were evaluated by Microsoft Word
software 2018. For checking the number of typing
errors, Word software “spelling and grammar” com-
mand was used, and the error rate was evaluated by
visual inspection and counting the errors. To check
the number of the written words, the number of typed
words in this software was used.
2.2.7. Data analysis
In this study, after collecting the data, the RULA
technical scores were first reported as a final score
with descriptive statistics. After examining the nor-
mality test using the Shapiro-Wilk test, the scores for
the discomfort scale and performance revealed that
the data were non-normal. Therefore, by considering
each participant as their control group, the Wilcoxon
signed-rank test was used to compare the results of
different conditions. A p-value of less than 0.05 was
considered to be statistically significant for all the
tests.
3. Results
Out of 28 accomplished RULA worksheets, 4
worksheets had the worst grand score for two study
conditions. The worst postures were related to par-
ticipant No. 3 with or without using the laptop
desk, respectively. Table 1 shows the RULA scores
and related action levels. When the participants per-
formed the typing task using the laptop desk, the
action level was calculated 2, which meant “further
investigation is needed and changes may be required.
On the other hand, without using the laptop desk, the
action level was calculated 3, which implied “investi-
gation and change are required soon”. A typical body
posture during both experimental conditions is shown
in Fig. 3.
Regarding the results of LPD for all participants,
the Wilcoxon signed-rank test showed that there was
a statistically significant difference between the per-
ceived discomfort in the neck, shoulder, and wrist
regions (P= 0.01, 0.04, 0.01), respectively. However,
the results were not significant for trunk and finger
regions (P= 0.12, 0.14). Figure 4, shows the mean
LPD scores for both study conditions.
The results regarding performance are shown in
Table 2. On average, the participants typed 381 and
375 words in the study conditions of with and with-
out the laptop desk, respectively. Additionally, the
mean typing error was significantly higher when par-
ticipants did not use the laptop desk (19 errors, P=
0.03).
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Fig. 4. Mean scores of LPD in the neck, shoulder, trunk, wrists and fingers. Error bars show standard deviations. The Significant results of
the Wilcoxon signed-rank test are marked by (∗).
Table 2
Results of Wilcoxon signed-rank test on typing task in both study conditions (N= 14)
Performance Typing conditions Mean ±SD p-value
The mean No.words Without laptop desk 375 3.80 0.07
Using laptop desk 381 5.36
Mean Typing Error Without laptop desk 19 1.42 0.003
Using laptop desk 12 1.20
4. Discussion
The main purpose of this study was to design
and manufacture a laptop desk for wheelchair users,
and to identify its ergonomic advantages during a
typing task. During the first phase of the study,
necessary design specifications were identified by
an expert panel, and the laptop desk was proto-
typed accordingly. The second phase of the study
was aimed for ergonomic evaluation of the furni-
ture during a simulated typing task. The data analysis
demonstrated that the new laptop desk could improve
body posture, and decrease discomfort, and typing
errors.
In the condition of not using the desk, the results
obtained from the worst case by the RULA technique
showed an action level of 3 which implied “Investi-
gation and change are required soon”. Based on the
results of the different regions of the RULA tech-
nique, when a person is not using a laptop desk, the
wrist is kept in an inappropriate bending angle of up
to 15 degrees, which is a risk factor for wrist muscu-
loskeletal disorders such as Carpal Tunnel Syndrome
(CTS) [32]. This condition was a result of the laptop
placement in a semi-reclined position on participants’
lap and the wheelchair armrest. Additionally, placing
a laptop on the lap causes the neck to bend more away
from the neutral position, which can manifest itself
in a high score in the RULA technique [22].
After using the new desk, the results revealed that
participants’ posture was corrected as the RULA
action level decreased from level 3 to 2 implying
“further investigations are needed and changes may
be required’’. Such reduction pointed to a less risky
environment regarding the posture of the participants.
Compared to other body regions, the wrist and neck
areas were more positively affected by the usage of
the new laptop desk. By using the new desk, the
neck angle was corrected considerably, which was
due to the possibility of manipulating the horizon-
tal angle of the desk (tray’s slope). Besides, when
the laptop desk was used, the participant’s forearms
and hands were put on the laptop desk. Therefore,
wrist’s posture was improved by reducing wrist’s
flexion and lateral deviation angles. These findings
are consistent with the literature, according to which
improved workstation design have reduced risk fac-
tors of musculoskeletal disorders [33, 34]. Correcting
wheelchair users’ posture by accommodating their
workstation is considered among ergonomic inter-
ventions that reduce musculoskeletal disorders risk
factors [25, 35]. Additionally, wheelchair users’ com-
plications such as fatigue, pain, physical weakness,
inability to work long periods may be improved [7, 8].
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In addition to improving participants’ posture,
using the laptop desk was also associated with lower
levels of discomfort in the upper extremities. The
difference was statistically significant for the neck,
shoulder, and wrist regions. As the condition of pos-
ture is improved (toward a more neutral posture), the
comfort level increases; That is, because in a neutral
posture muscles are under less demand, the per-
ceived exertion is less as well. According to Hyness
et al., changing posture from upright to supine on a
wheelchair during a typing task can reduce discom-
fort [36]. It is also shown that the height of chairs and
their arm rests are associated with improper upper
extremity postures and these factors can contribute to
musculoskeletal pain among computer office work-
ers [37]. In the present study, according to the RULA
scores (scores A and B), the postures of the neck,
shoulders, and wrists were improved by using the
laptop desk. Therefore, participants felt more com-
fortable in those regions.
In contrast to the neck, shoulders and wrists, alter-
ing the working layout did not make a significant
difference in the trunk and fingers’ posture. Because
the trunk region was immobile and the participants
were reclining to the wheelchair’s backrest. Discom-
fort evaluation in Hyness et al.’s study also showed
that the largest area of discomfort were upper extrem-
ities while trunk was not much of a concern [36].
Fingers were also in the same situation after using
the new furniture, and their posture condition did
not change noticeably. In addition, grooves were
designed on the tray to transfer laptop heat, which
may have resulted in reduced heat discomfort effects;
however, we did not assess it in this study. Moreover,
without using a laptop desk, the wheelchair users put
the laptop on their lap which could lead to discomfort
in the region of the legs. However, such discomfort in
the lower extremities was not tested, since some par-
ticipants did not have any sensation in those regions.
Based on the results of Table 2, the typing perfor-
mance of the participants, in the case of using a laptop
desk, showed a significant improvement for typing
accuracy; However, there was no statistically signif-
icant difference between two conditions for typing
speed (total written words). By using the laptop desk,
on average, participants could type 6 more words, and
they had 7 or fewer errors. A plausible explanation
is that the improvement of posture and reduction in
discomfort may have led to the reduction of typing
errors. In a similar study, Haynes and Williams (2008)
found that altering posture of participants during a
typing task on the wheelchair could impact typing
accuracy although any improvement in typing speed
needed more investigation [36]. It is also important to
recall that participants were instructed to perform typ-
ing tasks with their own pace and accuracy; that could
be a reason why typing speed remained unchanged
in this study.
Other studies have indicated that a new design or
adding new enhancements such as Brain-Computer
Interface (BCI), touchpads, and audio interfaces, can
play a significant role in improving performance
of wheelchair users regarding typing tasks [9–12];
hence, their specific occupational performance can
be enhanced [19, 38]. Kannan et al., showed that
a new design for wheelchair users could improve
their performance, which is in line with the results
of the present study [38]. On the other hand, task per-
formance can also be influenced by other variables.
Seizo’s study showed that people’s performance
including their accuracy and speed of typing not only
depends on the body posture, but it is also associated
with the design of the laptop itself, e.g., its keyboard
size [39, 40].
Poor workstation design and inability to achieve
equality in the workplace have led to exclusion of
wheelchair users from physical worksite environ-
ment [4], and their low employment rate [3]. There
are many alternatives recommended by other stud-
ies to improve wheelchair users’ employment. These
solutions comprise low-cost technologies, modified
workstations, working from home and using Uni-
versal Design principles [4, 41, 42]. According to
Arlati et al. and Whiteneck et al., new design and
additional accessories for wheelchairs could improve
wheelchair users’ accessibility and quality of work-
life; thus, foreseeing wheelchair users’ requirements
and implementing them into their workstation design
should be considered as a part of their quality of work-
ing life improvement programs [43, 44]. With this in
mind, we believe using an extra device such as the
present laptop desk could help wheelchair users to
cope with their work challenges in a more inclusively
designed environment.
One limitation of the study was that, although
the researchers sought to comply with all the stan-
dard requirements of an experimental study, because
the laptop desk was designed and evaluated by the
researchers themselves, the results may have been
influenced by the researcher’s own potential bias. The
second limitation of the study was evaluating the lap-
top desk through one type of task. Other tasks such
as browsing on the internet may show other results.
The third limitation was about the measurement
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1184 B.B. Naeini et al. / Design and ergonomic evaluation of a laptop desk
instruments of the study. As using objective methods,
such as electromyography, can confirm the results of
the subjective tools; they could be valuable to build
a more concrete evidence to complement the results.
The fourth limitation was that because the study pop-
ulation was difficult to access, it was not feasible
to gather a representative sample of people with a
variety of pathologies or anthropometric characteris-
tics; Such limitation may have affected the results
of the study although we believe that the adjusta-
bility of the furniture could have provided similar
accessibility for a more diverse population. Overall,
these results suggest that using a laptop desk has the
potential to be an effective intervention; However,
future work is needed to assess its longer-term con-
sequences (e.g., quality of work life, benefits, side
effects, employments, changes in work strategies)
among larger populations.
5. Conclusion
The results of the study showed that using a
novel desk for laptop usage of wheelchair users
could be very effective in improving upper body
posture and reducing local perceived discomfort in
the neck, shoulders, and wrists. The new furniture
also improved typing accuracy of the participants
although typing speed remained unaffected. These
findings add to the growing literature on the effects
of appropriate working layout on health and perfor-
mance of wheelchair users.
Acknowledgments
This article was developed under Project No. 1351
/T/95attheDepartment of Ergonomics, University
of Social Welfare and Rehabilitation Sciences. The
authors thank all participants for their kind collabo-
ration.
Conflict of interest
The authors have no conflicts of interest to declare.
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