Redesign and Fabrication of a Folding Ergonomic Laptop Desk for

471

Ergonomic laptop desk for college students

J Health Sci Surveillance Sys October 2022; Vol 10; No 4

Redesign and Fabrication of a Folding

Ergonomic Laptop Desk for College Students

Mojtaba Jafarvand

, MSc;

Saeid Ahmadi

, PhD; Ali

Safari Variani

, PhD; Sakineh

Varmazyar

, PhD

Department of Occupational

Health Engineering, Faculty of Health,

Qazvin University of Medical Sciences,

Qazvin, Iran

Department of Occupational Health

Engineering, Social Determinants

Health Research Center and Research

Institute for Prevention of Non-

Communicable Diseases, Faculty of

Health, Qazvin University of Medical

Sciences, Qazvin, Iran

Correspondence:

Sakineh Varmazyar, PhD;

Department of Occupational Health

Engineering, Social Determinants

Health Research Center and Research

Institute for Prevention of Non-

Communicable Diseases, Faculty of

Health, Qazvin University of Medical

Sciences, Qazvin, Iran

Tel: +98 28 33359501, Int. 3737;

Email: [email protected]

Received: 20 July 2022

Revised: 14 August 2022

Accepted: 17 September 2022

Original article

Abstract

Background: Awkward posture during work is one of the most

critical risk factors for musculoskeletal disorders. A laptop

desk tting with users’ body dimensions plays a crucial role

in maintaining proper posture and reducing musculoskeletal

disorders. This study aimed to redesign and fabricate a folding

ergonomic laptop desk for college students.

Methods: In this experimental applied study, two hundred and

seven college students were considered participants to design an

ergonomic laptop desk and fty students for posture evaluation.

Six anthropometric dimensions were measured: height, the height

of elbows in the sitting position, elbow-elbow breadth, the length

and height of both knees in the cross-legged sitting posture, and

the length of the elbow-ngers. Then, two best-selling laptop

desks were selected and the RULA method assessed laptop users’

posture. Finally, using students’ anthropometric dimensions

(n=207), a new laptop desk was designed and built in 2017.

Results: The height of our designed laptop desk is adjustable

(range of 20-28 cm), with a variable inclination of the desk (0- 34

degrees). It is possible to shorten or lengthen desk legs (48-72

cm), and a special plate of the mouse (19×46 cm) supports both

elbows on the sides of the desk. RULA method showed action

level 3, which required early change in desks 1 and 2.

Conclusion: Applying user›s and expert opinions, measuring

users› body dimensions, and applying those dimensions in design

and construction can play a signicant role in improving and

correcting the laptop›s desks so that it could result in suitable

posture in students.

Please cite this article as: Jafarvand M, Ahmadi S, Safari Variani A, Varmazyar

S. Redesign and Fabrication of a Folding Ergonomic Laptop Desk for College

Students. J Health Sci Surveillance Sys. 2022;10(4):471-479.

Keywords: Anthropometry, Desk, Design posture, RULA, Student

Introduction

Nowadays, with increasing development in all scientific

and research fields, it is not possible to carry out many

tasks without the aid of a computer. Furthermore,

advancements in technology and micro-processes,

battery technology, and improvement in storage capacity

have resulted in the creation of portable computers,

which are also referred to as laptops.

1, 2

Given the nature

of the laptop in terms of its portability, lightweight, and

processing capabilities similar to desktop computers, it

has become popular among people, especially students

in recent years.

A study conducted on 154 students in

the United States indicated that 88% of people preferred

laptops to desktop computers to perform their tasks.

Students frequently prefer to sit on the floor rather than

behind a desk or office chair habitually because it would

be more convenient to use the laptop in various positions.

Such people maintain an inappropriate physical posture

while using a laptoplying on the floor and placing the

laptop on their legs or other objects. The study carried

out by Rafiei et al. on 300 students in Tehran confirms

the mentioned statement.

Thus, awkward postures

cause discomfort in stressed organs and lead to chronic

disorders in long time exposure.

6, 7

Bubric reported that

over 53% of participants experienced musculoskeletal

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Jafarvand M, Ahmadi S, Safari Variani A, Varmazyar S

J Health Sci Surveillance Sys October 2022; Vol 10; No 4

discomfort while using a laptop computer.

In addition,

previous studies on musculoskeletal disorders (MSDs)

in students who used laptops indicated the greatest

discomfort in the students’ neck, shoulders, and wrists.

Also, results showed a high prevalence of neck pain

(69.19%) due to laptop use among students.

Working

with a laptop without using a desk can increase neck

discomfort (25-50%) and back pain (15-30%).

So, there

was a positive correlation between differential patterns

of laptop use and musculoskeletal discomfort.

A study by Moet et al. demonstrated that a

workstation is one of the factors aecting physical

variables of the body, so people who used laptops

on their legs reported more musculoskeletal pain

than those who sat behind a desk.

Therefore,

incompatibility of the bodily dimensions of students

with laptop desks in the position of cross-legged

sitting will aggravate musculoskeletal disorders in

the limbs involved while working with their laptops.

The product must be appropriately designed to be

suitable for all people, considering its adjustability and

sizes. In order to optimize such decisions, we require

anthropometric characteristics of the user population

to create an eective match between the product and

the user.

Inappropriateness between technology and

users has negatively impacted work eciency and

resulted in a high rate of musculoskeletal disorders

in workplaces.

The tools and facilities could

be designed and applied safely for the whole life

considering anthropometry science.

14, 15

Therefore, it

is essential to pay attention to user features in order to

design ergonomically friendly products and decrease

musculoskeletal disorders.

An awkward posture is one of the most important

MSDs risk factors in workstations.

RULA features

in assessing posture, force, and repetitive movements

identify MSDs risk factors in the upper extremities

during work.

The main issue in obtaining a proper design is

that human beings are signicantly dierent from

one another in terms of various biological aspects

such as their physical dimensions, mentality, and

intelligence.

19, 20

Mostly, designers and engineers must

ensure comfort, safety, eciency, and health of users

during products design It should be better to consider

capabilities and limitations of the human physical and

mental abilities in the design and production of such

equipment.

Therefore, this study aims to redesign and

fabricate a folding ergonomic laptop desk for college

students. So, the innovation of the present study is to

discover the problems of existing laptop desks from the

perspective of students and professionals and use their

opinion in the construction of an adjustable and folding

laptop desk which would be usable by both hands

based on anthropometric dimensions of students.

Methods

Samples

The university ethics committee has authenticated

this experimental applied study under the code of

IR.QUMS.REC.1395.186. This study was carried out

on students living in Qazvin University of Medical

Sciences dormitories in 2017. After informing the

students, those who showed their willingness to

cooperate entered the study by obtaining verbal

consent. Based on the previous studies,

the sample

size was estimated at 185 participants, considering

the 95% condence interval and standard deviation

of 0.347 mm. The subjects were selected by simple

classification-randomization among students.

Regarding the students’ interest in participating in

the study, 207 people were analyzed.

Also, Based on the previous studies

, the sample

size to evaluate students’ posture while using laptop

desks was estimated to be 48 participants, taking into

account the 90% condence interval and prevalence of

77%. In order to obtain more accurate data, two more

participants were added to the estimated samples. So,

the nal sample was about 50 participants. The sample

data was collected in dormitory by simple random

sampling.

Measurement of Anthropometric Dimensions in

Students (n=207)

In this study, six anthropometric dimensions of

the students were measured including height, elbow

height while sitting, the width of elbows, length of

both knees in a cross-legged sitting posture, the

height of both knees in a cross-legged sitting posture,

and the elbow-ngertip length (Figure 1).

12, 22-24

Anthropometric dimensions were measured using

tape or static anthropometer device (Two vertical

rectangular plates with a horizontal oor that the

length and width of each plate was 135 cm and 200 cm,

respectively with accurately measured 1 millimeter,

and an adjustable chair), digital calipers, Marcal 18

EWR, with a movable jaw (with measuring range

0-500 mm and 0-1000 mm with resolution 0.01 mm),

a goniometer with an accuracy of one degree, and a

special scale for weight. At the time of measurement,

the individuals had minimal clothing and were

assessed in a sitting position with their heads resting

on the anthropometer plate.

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J Health Sci Surveillance Sys October 2022; Vol 10; No 4

Determining the Dimensions of Current Laptop Desks

and Examination of Their Problems

The dimensions of the current best-selling desks

on the market (Figure 2) were measured, which

include the total length and width of the surface on the

desk, the longitudinal distance of the desk legs from

each other, adjustable desk height from the level on the

desk and adjustable desk height from the level under

the table. Appropriate percentiles were considered to

compare students’ anthropometric dimensions with

the current desks’ dimensions (Table 1).

In the next stage, the ergonomic issues of laptop

desks used in cross-legged sitting positions were

identied by the researcher, a group of ergonomics and

occupational health experts, and industrial designers.

Then, the ergonomic suggestions from students

were gathered fora better design of existing laptop

desks. Furthermore, ergonomic issues and students’

suggestions were discussed in a symposium with a

group of well-known experts, and the initial design

was drawn.

Posture Analysis While Utilizing Current and

Designed Laptop Desks (n=50)

According to Tirgar’s study, students usually

spend more than one hour working on computer

workstations.

Therefore, all laptop desks were

used at least one hour before analyzing participants’

postures by RULA: Rapid Upper Limb Assessment

method. RULA method assesses the posture of the

dierent regions of the body, especially in the upper

extremities, force or load, and muscle activity (static

posture or repetitive movements).

Generally, it is common to classify and assess all

the body parts in two groups by the RULA method.

These groups include group A (upper limbs including

shoulders, elbows, wrists, and hands) and group B

(neck, trunk, and legs).

Each group was analyzed and

scored separately based on the table method. Following

that, repetition and force scores were considered to

calculate the nal RULA score (Figure 3).

The priority level of corrective action of the RULA

method is demonstrated in Table 2.

Design and Fabrication

Experts’ and students’ corrective suggestions

were applied to design a new desk in the VISIO

Microsoft Oce environment. First, the initial sketch

was drawn according to an appropriate percentile of

anthropometric dimensions in Table 1. Then, the

prototype of the laptop desk was made using double-

layer cartons and wood.

Following that, based on the expert group’s

decision and troubleshooting, the wooden laptop desk

was constructed.

Figure 1: Measured anthropometric dimensions

Figure 2: The current best-selling desks on the market

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J Health Sci Surveillance Sys October 2022; Vol 10; No 4

Result

Demographic Characteristics

The results showed that the mean and standard

deviation of the age for the students who participated

in anthropometric dimensions measurement (n=207)

and those who used laptops to evaluate posture (n=50)

as 20.82±1.56 and 21.72±2.38 years, respectively.

Other demographic characteristics of the subjects

have been presented in Table 3.

Current Laptop Desks Problems

Our study showed that there were major problems

in the rst current laptop desk, including lack of a

paper holder, lack of adjustability of desk legs, no

special mouse plate, Lack of ability to adjust the

inclination of the laptop and mouse plate separately,

having sharp edges on the desk, and no elbow support

for the rest when typing or working with the mouse.

In addition to the problems mentioned above, there

were other problems in the second current laptop desk

such as xed special mouse plate, lack of special mouse

plate for left-handed operators, adjustable laptop plate

in just two inclinations of 0 and 27 degrees and of its

failure to attract operators who like having desks with

adjustable height.

Anthropometric Dimensions of Fabricated Laptop

Desk

The anthropometric dimensions regarding the

length of both knees in the posture of cross-legged

sitting have the 5

percentile of 48.85 cm and the 95

percentile of 70.26 cm. Other characteristics regarding

the anthropometric dimensions have been presented

in Table 4.

According to Figure 4, the total surface length

of the constructed table was measured to be 90 cm.

In addition, this table features 9 inclinations with

Table 1: Properties percentile for each anthropometric dimension in designing the laptop desk

Desk parameterProperties percentileDimension of the body

Longitudinal distance of the desk legs from each other5-95Length of both knees in the cross-legged posture

Adjustable desk height from the level under the table5-95Height of both knees in the cross-legged posture

Adjustable desk height from the level on the desk5-95Height of the elbows in the sitting position

The total length of the desk95Elbow-elbow breadth

Width of mouse handles95Length of the elbow- ngers

Table 2: Interpretation of the nal score in the rapid upper limb assessment method

The nal score The priority level of corrective action Interpretation

1-2 1 Acceptable posture

3-4 2 Further investigations, changes may be needed

5-6 3 Further investigations, change soon

7 4 Investigate and implement change

Figure 3: Scoring by the RULA method

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Table 3: Demographic characteristics of the participants (n=207) and current laptop desks users (n=50 )

Laptop users (n=50)Participants (n=207) Variable

Mean±SD

or Percent

NumberMean±SD

or Percent

Number

21.72±2.385020.82±1.56207Age (year)

168.92±8.3750168.14±9.01207Height (cm)

63.58±11.165062.78±11.45207Weight (Kg)

341739.682Male Sex

663360.4125Female

849.720Operation room Field of

Study

221121.344Occupational health

848.217Environmental Health

217.215Public health

1059.720Nursing

421.94Medicine

422.45Dentistry

428.217Laboratory sciences

2110.121Medical emergencies

1055.812Midwifery

22119.720Healthcare management

425.812Anesthesia

Table 4: Anthropometric dimensions in the students (Cm)

95ile50ile5ileMaximumMinimumMean±SDAnthropometry Dimension

70.2658.2048.858141.3558.17±6.44Length of both knees in the cross-legged posture

2823.5020331523.72±2.50Height of both knees in the cross-legged posture

2924.5019.20361724.50±2.84Height of elbows in the sitting position

51.0940.9235.1756.1525.5341.59±4.80Elbow-elbow breadth

49.7644.1539.3052.3634.2044.37±3.23Length of the elbow-ngers

ile: Percentile

Figure 4: Laptop desk designed and built (from a dierent perspective)

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J Health Sci Surveillance Sys October 2022; Vol 10; No 4

intervals of 4.25 degrees. The other dimensions of

the constructed table have been presented in Table 5

and Figure 4.

Comparison of Fit between Students’ Anthropometric

Dimensions with Current and Fabricated Laptop

Desks

The results of matching the anthropometric

dimensions of students with the dimensions of the

desks showed that the length of both knees in the

cross-legged posture with the longitudinal distance

of the desk legs from each other in desks 1, 2, and

fabricated ones were 32.4%, 61.8%, and 95.7% t,

respectively.

However, two types of the most common laptop

desks on the market had anthropometric proportions of

about 32% in only three anthropometric dimensions,

and our fabricated laptop desk had a proportion of

more than 70% in four anthropometric dimensions

(Figure 5).

The Corrective Action Priority Level of Various

Laptop Desks

The level of corrective action 2 showed that further

investigation and changes may be needed in desks 1,

2 and fabricated desks with a rate of 82%, 92%, and

74%, respectively, which means that the fabricated

desk has a more suitable posture for users (Figure 6).

Discussion

Using laptops has resulted in musculoskeletal disorders

in users, especially among students. On the other hand,

designing a new product or rectifying the design of a

product is mostly based on a clear understanding of

users’ needs and the demands of operators. Furthermore,

one of the ways to improve the design and increase user

health and satisfaction is to identify, collect, and solve

the problems of existing desks used by users. Therefore,

the present study has tried to identify the problems of

best-selling laptop desks used in the cross-legged sitting

posture through students’ and experts’ opinions. In

Table 5: Dimensions of laptop desk designed and built and current laptop desks (Desk 1 and 2)

Dimensions of the laptop desk Size (Cm or Degree)

Made desk Desk 1 Desk 2

The total length of the surface on the desk 90 61 63

The total width of the surface on the desk 46 34 35

Longitudinal distance of the desk legs from each other Min 48 54.5 60

Max 72 54.5 60

Adjustable desk height from the level on the desk Min 28 20 26

Max 36 31 26

Adjustable desk height from the level under the table Min 20 18 18

Max 28 29 18

Adjustable laptop plate inclination Min 0 2.6 0

Max 34 7.8 27

Adjustable mouse plate inclination

(Left and right)

Min 0 2.6 0

Max 0 7.8 0

Laptop plate dimensions Length 50 - 46

Width 34 - 35

Mouse plate dimensions

(Left and right)

Length 19 - 17

Width 46 - 35

Figure 5: Percentage of t of anthropometric dimensions of students with the dimensions of laptop desks

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J Health Sci Surveillance Sys October 2022; Vol 10; No 4

addition, anthropometric dimensions of students have

been used to optimize a laptop desk ergonomically to

improve students’ posture in cross-legged sitting.

In this study, the problems of purchasing two

desks such as lack of adjustability in desk legs , no

special mouse plate, lack of paper holder, lack of

adjustability in the inclination of the laptop and mouse

plates separately, the sharp edges of the desk surface,

not-being foldable and not-being portable showed

that it would be necessary to consider and solve the

problems above in new laptop desk design. Our study

is similar to the Purnomo study, which designed a

student laptop desk to identify the problem, nd

ideas and recommendations, implement, and evaluate

recommended solutions.

The results of students’

posture evaluation when using desks 1 and 2 showed

that the problems in the desks mentioned above, lead

to awkward posture in the neck, trunk, arm, and wrist.

So, further investigation and change may be needed

(action level 2), or a change soon (action level 3) is

required. This result is in good agreement with the

Gautam ndings

and Kaur’s, which is supported by

RULA scores ranging from 3–6 (action level 2, 3),

indicating risk at the workstation.

Users, professors, and experts’ opinions

concerning our new fabricated desk led to a more

acceptable level of corrective action (action level

3=change soon 0%) compared with existing desks.

So, the risk of developing musculoskeletal disorders

and fatigue would be decreased with eliminating

previously mentioned problems in existing desks, and

operators’ posture would be improved while using the

new laptop desk.

Few studies have been carried out on the design and

fabrication of laptop desks in the cross-legged sitting

position based on the anthropometric dimensions of

students in Iran or other parts of the world. Therefore,

it was hardly ever possible to compare the results of

the present study with other similar studies.

In the present study, the anthropometric dimensions

of male and female students according to the 5th

and 95th percentiles were used to design dierent

parts of the laptop desk in the cross-legged sitting

posture, which is very close to the anthropometric

data of Mououdi et al. So, it indicates the accuracy of

measuring dimensions among students in this study.

Studying the proportionality of students’

anthropometric dimensions with the dimensions of

desks showed that the longitudinal distance of the

desk legs from each other in desks 1 and 2 t about

one-third to two-thirds, respectively. It means these

desks could not be easily used on average by almost

half of the users in the cross-legged posture. On the

other hand, participants could easily operate our new

fabricated desk due to the adjustability of the desk

legs from each other. Moreover, in desk number 2,

the space under the desk for the knees is suitable for

almost 1% of people due to the xed height of the

desk. In contrast to the existing desks, the fabricated

one would be more applicable to most users, as it is

possible to adjust the knee space, which is in line with

the range of accommodation distance between the

desk bases in the study conducted by Mououdi

et al.

In the dimension of the height of both knees in

the cross-legged sitting posture, desk 2 had the least

adaptation to the anthropometric dimensions. In

contrast, our fabricated desk has a lot of matching,

consistent with the study of Mououdi

et al.

Musculoskeletal pain, including neck and upper back

pain, can be reported during laptop use when working

at the unsuitable -height table.

There was no good t between the height of the

upper surface of the fabricated desk and the height

of the users’ elbows such that t proportionality was

measured to be one-ve. Moreover, it should be noted

that this proportion in the new laptop desk was less

Figure 6: Frequency of RULA method corrective action level on laptop desks

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J Health Sci Surveillance Sys October 2022; Vol 10; No 4

than other existing desks. The reason behind this

nding is that the distance between the upper and

lower surface of the fabricated desk was thicker, about

8 cm, in order to fold legs and special mouse plates

from the two sides of the desk in such a manner that

it could be handled as a portable desk.

The lowest proportion percentage was measured

between the minimum length of students’ elbow-

ngertip with the width of best-selling existing desks

numbers 1 and 2. However, this proportionality was

remarkably increased in the newly built desk.

The built of a laptop desk is considered superior

to laptop desks available on the market as opinions of

students and professionals were taken into account.

The fact that it has features such as being adjustable

(in terms of the desk height, the distance between the

desk legs, and the special laptop plate) enabled working

with the mouse with both hands, having elbow support,

being equipped with a paper holder during typing,

reducing neck disorders, and easy and convenient

movement in a bag. A study carried out by the rst

author and colleagues evaluated student satisfaction

rate with the best-selling laptop desks indicated that

laptop desks that are close in design and capabilities to

this constructed desk are more satisfactory.

Conclusion

As far as the design and construction elements allow, the

present laptop desk is made based on the 5th and 95th

percentile anthropometric dimensions (length, width,

and height) so that the final product provides more

strength and durability. It seems that using our fabricate

desk might be effective in reducing MSDs and their

long-time complaints among students. Thus, it would

be recommended to consider a broad age group with

different working postures in future studies to provide

more comprehensive results that could be generalized to

wider society. Furthermore, the existing shortcomings

can be modified by considering the ergonomic

suggestions of designers and users, so the laptop desk

would be improved ergonomically. As a result, students’

postures would be maintained in a suitable position.

Advantages and Limitations of This Study

One of the advantages of the present study was to use

the opinions of students and ergonomics experts to

eliminate the shortcomings of existing laptop desks and

use their suggestions to improve the design of the built

laptop desk. In addition, using students’ anthropometric

features in designing desk dimensions, adjustable and

folding parts of the table, and making them usable for

left-handed and right-handed users are other advantages

of the present study. On the other hand, the limitation

of the study included using few available laptop desks

and the lack of research among all people (with different

ages) who use laptop desks.

Conflicts of interest: None declared.

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