The Impact of a Computerized Work Environment on Professional Occupational Groups and Behavioural and Physiological Risk Factors for Musculoskeletal Symptoms: A Literature Review

7/27/2019 The Impact of a Computerized Work Environment on Professional Occupational Groups and Behavioural and Physi

1/24

The Impact of a Computerized Work Environment on

Professional Occupational Groups and Behavioural and

Physiological Risk Factors for Musculoskeletal

Symptoms: A Literature Review

Karin Lindgren Griffiths Martin G. Mackey Barbara J. Adamson

Published online: 7 November 2007

Springer Science+Business Media, LLC 2007

Abstract Introduction Computers have become an essential tool for many office based

professional occupations, but their use is also accompanied by change to work demands and

psychosocial work environment. Whilst considerable research exists relating to the potential

health risks associated with computer work amongst semi-skilled occupations, there is a

paucity of knowledge regarding the impact of an increasingly computerized workplace on the

physical and psychological wellbeing of professional occupations. Methods A literature search

was conducted using OVID Medline, PsycINFO and Cinahl databases. Papers published

between 1980 and 2007 were selected for review. These included epidemiological and

experimental studies that explored the relationships among occupational demands and

stressors, work behaviours and musculoskeletal health in workers operating in a computerized

work environment. Results In response to workload, deadline and performance monitoringpressures, many professional workers are often encouraged to perform long hours of computer

work with high mental demands; work at a hectic workpace resulting in heightened muscle

tension and forces, and with inadequate work breaks. These factors were identified in this

review as risk factors for work related musculoskeletal symptoms. Conclusion As new tech-

nology continues to computerise the way professionals do their work, it is important for

organizations to identify and measure the risks to health and wellbeing associated with these

changes. Further research with professional groups is needed to support effective risk

management decisions.

Keywords Computer work Work related musculoskeletal symptoms

Psychosocial stressors

Professional occupations

K. L. Griffiths (&)CRS Australia, Australian Government, Canberra, Australiae-mail: [email protected]

M. G. MackeyDiscipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, NSW, Australia

B. J. AdamsonDiscipline of Behavioural and Community Health Sciences, Faculty of Health Sciences, University ofSydney, NSW, Australia

13

J Occup Rehabil (2007) 17:743765DOI 10.1007/s10926-007-9108-x


2/24

Introduction

The work environment for many skilled professional workers such as engineers, accountants,

lawyers and architects has substantially changed in modern times with the computerization of

their office workplace. An individuals work environment is formed by the work conditions at

the organizational level and the job tasks at the individual level [1], determining how andwhere work is organised and performed. Computerization of work tasks, information storage

and communication has provided many benefits to organizations and their staff, increasing

productivity and efficiency of work performance, improving quality of professional service

delivery to clients and enabling flexibility in when and where work is completed. It is esti-

mated that at least 76 million people in the United States used a computer in their workplace in

2003, accounting for at least 56% of all employed adults aged 18 years and older [ 2]. Of these,

a growing proportion are in managerial and/or professional positions (52.1% for men and

48.2% for women) and it has been estimated that more than 25% of the workforce now work

on a computer for more than half their working day [3].

However, computerization tends to change the way work is organised and therefore

impacts on both biomechanical and psychological work demands and conditions [4]. Workorganization is a characteristic of the work environment and deals with the way work is

structured and processed including hours of work, task complexity, skill and effort, job

control, work/break schedules etc. [5]. It is argued the technology made available by

computerization of office based work, may indirectly influence health status through how it

is able to structure a job and affect the psychosocial work environment [ 6]. Computerization

can also have negative consequences on workloads, deadlines and performance expectations

[7]. It has been suggested it can contribute to the dehumanizing of some office work

activity when it results in reduced opportunity for social interaction within a work envi-

ronment [89].

The computer has become a work tool for most office based professions. It has introduced

new, or added to existing work demands and psychosocial stressors within their work envi-ronment. Some of these are illustrated in Fig. 1, adapted from the Workstyle model developed

by Feuerstein [10, p. 191]. This diagram also identifies various individual behavioural or

physiological responses that can be triggered or exacerbated by the work demands and psy-

chosocial stressors within a computerized work environment, and suggests an impact on the

risk of work related musculoskeletal symptoms.

As tasks within a job become computerized, the biomechanical demands may subsequently

change. For professional workers this may include the introduction of more repetitive upper

limb work, with longer periods of sedentary postures, resulting in reduced task diversity and

variability of muscle activity [11]. Professionals working with computer aided design software

(CAD) such as engineers, design technicians and architects, may now spend many hours sitting

and viewing a monitor whilst operating a computer mouse. This will significantly reduce their

exposure to different kinds of tasks that provide biomechanical variation, thought to be par-

ticularly important for computer based work characterized by static loading [12]. Similarly,

professionals working with large numbers of clients may have adopted electronic filing sys-

tems in place of paper files within their workplace. This enables all client information to be

accessed from the computer workstation, with all paper based documents being converted to

electronic information. The benefits include increased speed of access, quality and effec-

tiveness of document handing [4], reduced demands on office space for file storage systems,

more flexibility in regards to where work is done, and it removes the risk of misplaced files.

Yet from a biomechanical perspective, it also removes the opportunity to stand and walk away

744 J Occup Rehabil (2007) 17:743765

13


3/24

from the office desk to locate a file or document, further lessening exposure to variability withthe physical demands within a job.

It is argued the psychological demands associated with the performance of some tasks with

professional work may be increased by their computerization [13]. Whilst many basic tasks

such as numerical calculations are simplified, others can become more complex. Additional

demands may include increased information processing requirements and greater demands on

attention and memory [5, 9, 14], high precision and concentration [15], and multi-tasking

demands. A recent study by Dux et al. [16], demonstrated a bottleneck effect when attempting

to execute two tasks simultaneously using a computer, with demonstrated neural limitations in

the information processing required for multiple task demands. It is now relatively common for

professional workers such as lawyers to draft documents on their desktop computer using

sophisticated computer software, work that was previously dictated to and completed by theirsecretarial staff. This task can require simultaneous manual operation of a computer, navi-

gation of professional software and at the same time perform work with high cognitive

demands including memory recall, problem solving and professional decision making. It is

argued by Hockey et al. [9] that greater demands are placed on working memory with com-

puterized work, particularly with interactive computer tasks. This work often has the

requirement to retrieve and keep track of a lengthy sequence of commands whilst working

towards the task goal. They also claim that the increased job-related information and com-

munication facilities delivered by computerization may result in greater demands on planning

and decision making processes, potentially requiring work to be organized into larger task

chunks.

Fig. 1 Risk factors for musculoskeletal symptoms within a computerized office work environment in relation toprofessional occupational groups. Adapted from Workstyle Model [10, p. 191)], for purpose of identifying onlythose variables and relationships addressed in this review and this does not diminish the significance of other

variables within the model. Used and modified with permission from Taylor & Francis Ltd (UK) (1996) andauthor M. Feuerstein

J Occup Rehabil (2007) 17:743765 745

13


4/24

Psychosocial work stressors are those psychological demands that are capable of evoking a

common stress response within employees. It has been suggested that the computerization of

office work has introduced new psychosocial stressors within office environments [17, 18], that

are additional to those already present in a job. They may include increased workload demands

[8], reduced discretionary control over task scheduling, increased workpace, deadline and

electronic performance monitoring pressures [6], the need for sustained concentration withdiminished social interaction [14], a sense of being rushed [19], and a tendency for increased

supervisory control with reduced autonomy [20].

Epidemiological evidence has demonstrated that computer based work is an important

biomechanical risk factor for the development of upper body work related musculoskeletal

symptoms and disorders [17, 2126], with the neck area being particularly vulnerable to the

adverse effects of this type of work [27]. Studies within this area have tended to define

computer based work in terms of hours per day or per week, and inclusion criteria have

included working on a computer more than 4 h per day or more than 15 h per week. The

biomechanical risk factors associated with computer work have been well established and

generally include prolonged periods of sitting and viewing the monitor, with sustained static

muscle activity in the neck, shoulder and spinal areas. Additional to this static loading arerepetitive movements of the fingers and wrists in order to operate a keyboard or mouse, a

significant risk factor for cumulative trauma disorders to the upper limbs, in particular tendons

within the hand and wrist [28].

There is growing evidence that psychosocial factors associated with computer work may

increase the risk of upper body musculoskeletal symptoms and disorders [2933], particularly

neck/shoulder pain [34]. These factors include the psychological work demands and psycho-

social stressors present within a work environment. Some researchers assert that psychosocial

risk factors are at least as important as the biomechanical risk factors in the aetiology of work

related musculoskeletal symptoms and disorders [35, 36] and may increase the effect of the

biomechanical loading [37, 38]. Professional occupations generally perform work character-

ised by high psychological demands when compared to semi-skilled occupations [39] and theyinclude problem solving, decision making, professional knowledge application, responsibility,

customer/client interaction, memory demands, creativity, ongoing skill and knowledge

development.

Whilst psychosocial stressors may be present in all computerized work environments, it is

suggested different stressors may be experienced between professional and non professional

workers. In one study with semi-skilled office workers, higher rating stressors included low

levels of: job control, skill utilization, social support and task clarity [ 40]. A study of pro-

fessional financial traders found the highest rating stressors within this occupational group

were: a profit goal (1), long working hours (2), time pressure (3), fear of mistakes (4) and

concentration (5) [41]. Wallace [42] cites several surveys with lawyers which found work

demands within this profession are a major source of stress. These include long work hours,time pressure and deadlines, information overload and working with a profit-driven focus. In

many professions a significant psychosocial stressor is the emotion work required during

interactions with clients or customers, particularly within helping professions where the

sensitivity requirements are often greater and long duration non-scripted verbal interaction is

more common [43]. Psychological demands and psychosocial stressors found to be associated

with an increased risk of work-related musculoskeletal symptoms include working to time

pressures and/or deadlines [41, 4448], mentally demanding work and high levels of con-

centration [18, 19, 49], perceived hectic workpace [50, 51] and electronic performance

monitoring [6].

746 J Occup Rehabil (2007) 17:743765

13


5/24

The majority of studies involving the measure of risk factors for musculoskeletal symp-

toms or disorders with computerized work, have examined the separate effects of

biomechanical or psychological demands and stressors and few have investigated their

combined or interactive effect [52]. Linton [53] found that exposure to both psychosocial and

biomechanical stressors resulted in higher estimates of risk for musculoskeletal symptoms

than each one alone. An interactive effect for workers exposed to both biomechanical andpsychological workplace risk factors was also reported by Devereux [54]. In this study using

a cross-section of occupations, workers exposed to both types of factor were at highest risk of

developing musculoskeletal symptoms. The potential for a synergist effect when exposed

to combined biomechanical and psychological risk factors has been suggested by some

authors [48, 52, 55].

It is argued that organizational factors can encourage certain workstyle behaviours and

physiological responses that may add to the existing risk of developing, exacerbating or

maintaining musculoskeletal symptoms [10, 29, 34, 45]. Workstyle is defined as a modifiable

response style that enables an individual to meet certain self and/or organizationally imposed

work demands [56, p. 88]. Adverse workstyles associated with computer based work, also

referred to as maladaptive coping behaviours [57], may include working long hours and/orat a high pace in order to keep output high, working with heightened levels of muscle activity,

taking inadequate work breaks [56, 57], and applying excessive forces to the keyboard or

mouse [58, 59]. Some of these factors have been identified in the literature as both biome-

chanical and psychological risk factors for the development of musculoskeletal symptoms [60,

61] and may be a voluntary behavioural or involuntary physiological response to organiza-

tional and/or self imposed work demands or stressors. It has been suggested that a workers

capacity to manage biomechanical and psychosocial work demands may partly explain why

some people exposed to similar work conditions develop musculoskeletal disorders while

others do not [62].

The expansion of computerized tasks into the work environment of many professional jobs

has created a new level of risk that does not appear to have been adequately addressed in theliterature. Most related research has been conducted with semi-skilled occupations such as data

entry and call-centre work and the transferability of the results of these studies into profes-

sional occupations is unclear. However, there is good evidence available which shows that

psychological demands and stressors characteristic of professional work, such as mentally

demanding tasks, high workloads and deadline pressures, are also strong predictors of risk for

musculoskeletal symptoms. These are additional to the existing biomechanical risks clearly

identified with computerized work with a potential interactive effect.

The present paper discusses several work behaviours and physiological responses that may

be an added risk factor for musculoskeletal symptoms within a computerized office work

environment amongst professional workers. These behaviours and responses were selected for

review based on a number of criteria including: proposed within the original Workstyle Model[10]; at least a moderate association with the risk of musculoskeletal symptoms [63], as

reported by authors in the studies selected for this review; the number of studies with sig-

nificant findings for each variable; and clinical observations of work practices amongst a range

of office based professional workers. The literature search strategy involved a search of rel-

evant electronic databases including Medline, Cinahl and PsycINFO, journals and websites

using a number of keywords including: computer work, musculoskeletal symptoms or disor-

ders, psychosocial stressors, workload; work or rest breaks. Relevant studies from reference

lists were also manually searched. Literature findings have shown that musculoskeletal and

psychological wellbeing can be adversely affected with behaviours and work demand

responses that result in working long hours and/or at a hectic workpace, working with a

J Occup Rehabil (2007) 17:743765 747

13


6/24

heightened psychophysiological reactivity including increased muscle tension or forces, and

taking inadequate work breaks. The aim of this paper is to draw attention to the potential risks

to musculoskeletal health with the computerization of work amongst professional occupational

groups, particularly where organizational factors enable or encourage individual work

behaviours and physiological responses that can significantly add to this risk.

Working Long Work Hours and Workload Pressures

Working long hours appears to be a growing occupational health issue throughout the

developed world. Recent labour statistics from the Australian Bureau of Statistics indicate the

average working hours for full-time workers has increased over the last two decades and

fathers of children under 15 years now spend an average of 43 h per week at work, with 33%

working more than 50 h per week [64]. A study by the Australian Institute for Family Studies

found the average hours worked by full-time employees in Australia have continued to

increase since the late 1970s [65]. Upper white collar workers were more highly repre-

sented, with 59.6% of males from this group reporting they worked more than 60 h per weekand 57.9% worked 4959 h per week. A more recent study of legal practitioners in NSW

found the average weekly working hours in 2004 for male lawyers was 50.9 h and 48.1 for

female lawyers [66].

There is a growing body of evidence that suggests working long hours has an adverse effect

on health and wellbeing in general, with an increased risk of occupational stress, cardiovas-

cular disease and musculoskeletal disorders [67]. When longer hours are worked with a

computer, the duration of exposure to the biomechanical and psychological loading associated

with computer work is increased. More hours at the office will also increase the exposure time

to the psychosocial stressors associated with the job and reduces time available to wind down

and recover after work. Oberlechner and Nimgade [41] found long working hours was rated as

the second highest source of work stress amongst the group of financial traders studied.Inadequate unwinding after work was identified by Melin and Lundberg as a significant risk

factor for work related musculoskeletal symptoms [37]. They identified a slow reversal of the

stress response developed as a consequence of mental and physical work demands, as an

important mechanism in sustained heightened muscle tension after finishing work and the

development of work related musculoskeletal problems. Work conditions which require more

hours of work under workload pressures will reduce the number of hours in a day to recover

and opportunity to reverse the physiological stress response developed whilst at work.

Epidemiological studies involving a range of occupations have shown there is a significant

relationship between daily duration of computer use and the risk of musculoskeletal symptoms

[35, 47, 6873]. The main findings from these studies are summarised in Table 1. Palmer et al.

[74] found that operating a keyboard for more than 4 h per day was associated with a 4-foldincrease in risk of neck and shoulder pain compared with those who used a keyboard mini-

mally. Nakazawa et al. [75] gathered data from over 25,000 clerical workers and found a

significant relationship between biomechanical symptoms and duration of daily computer use,

after adjustment for confounding factors. A significant association between reported neck/

shoulder pain and duration of computer work per day was also reported by Kamwendo et al.

[22]. The results of their cross-sectional study of 420 medical secretaries suggested the risk of

neck/shoulder pain significantly increased with 5 or more hours spent working on a computer

per day. Similar results were obtained by Jensen et al. [ 71], who found the risk of neck or

shoulder pain amongst women increased linearly as the proportion of work time at a computer

per day increased. One study with non-clerical workers from seven different workplaces

748 J Occup Rehabil (2007) 17:743765

13


7/24


8/24

Table 1 continued

Reference Study population Study design Risk factor Findings

Jensen et al. [81] Range of computerbased jobs(Denmark)

(n = 3,475)

Cross-sectional Hrs working withcomputer/day

Duration a predictor ofneck and shouldersymptoms amongst

women (OR = 1.92,95% CI: 1.213.02 &OR = 1.83, CI: 1.132.95 respectively) &predictor of hand/wristsymptoms amongstmen (OR = 2.76, 95%CI: 1.515.06)

Kamwendo et al.[22]

Female medicalsecretaries(Sweden)(n = 420)

Cross-sectional Hrs working withcomputer[5 h/day

Significant associationbetween[5 h/daycomputer work & neck/shoulder pain

Karlqvist et al.

[55]

Computer operators,

46 worksites,various occupations(Sweden)(n = 1,529)

Cross-sectional Duration of

computer usewith and/without breaks

Duration of computer

work a strong predictorof symptoms

Time pressure associatedwith higher prevalenceof symptoms in femaleworkers

Lassen et al. [72] Technical & machinetechnicians(Denmark)(n = 6,943)

Prospective Duration ofkeyboard andmouse use

Significant increased riskof elbow & wrist/handpain with time spentusing mouse orkeyboard, with nothreshold effect for

mouse useLeroyer et al. [73] Office administrative

workers (France)(n = 762)

Cross-sectional Workingadditional hoursto normal week

Increased prevalence ofneck pain foremployees who workedlonger hours(OR = 1.43, 95% CI:0.992.07)

Nakazawa et al.

[75]

Clerical workers

(Japan) 25,96429,711

Cross-sectional

three studiesover 3 year

period

Duration of daily

computer use

Duration lineally related

to MS symptoms scorewith no threshold

effect. Consistentfindings over 3 yearperiod

Palmer et al. [74] Range of occupations(UK) (n = 12,262)

Cross-sectional Keyboard use[4 h/day

Four-fold increase risk ofneck/shoulder pain with[4 h keyboard use perday

Polanyi et al. [47] Newspaper workers(Canada)(n = 1,007)

Cross-sectional Daily timekeyboarding

Duration of keyboard usewas predictive ofmusculoskeletalsymptoms

Fast work pacedeadlines

Frequent deadlines andfast work paceincreased risk ofmusculoskeletalsymptoms

750 J Occup Rehabil (2007) 17:743765

13


9/24

including a government department, accounting and legal firm, found the hours of computeruse per week was not a predictor of neck and shoulder pain [ 76]. The only predictive effects

were found with perceived tension at work and gender (female). In the case of wrist/hand pain,

Bernard et al. [44] suggested a possible dose-response with the number of hours spent typing,

with a greater than twofold risk for those typing more than 6 h per day.

Quantitative workload is defined as the amount of work the person is given to do (Yang

and Carayon [18, p. 33]), and is claimed to be a critical stressor with computer work. It has

been found that a computerized work environment may have the effect of increasing the

workload within an office [4, 18], with a tendency to increase the pace of work performed [ 19].

Waersted and Westgaard [11] demonstrated that when the same pen and paper task was

transferred to a computer aided task, the workpace tended to increase amongst the participants

in their study. A high workpace was found to be a predictor of neck and hand/wrist symptomsby Jensen et al. [77] amongst over 5,000 computer users from 11 different companies.

Fredriksson et al. [51] performed a longitudinal study over a 24 year period and found a

feeling of hectic work pace and mental exhaustion at the end of a work day was the most

common risk factor for neck and shoulder disorders amongst women. A study with enlisted US

marines completed by Huang et al. [48] found the reported pressure (on marines) to work

continuously and for such work to be completed urgently was associated with up to a twofold

increase in risk of low back and upper extremity symptoms. They also found that these

psychosocial risk factors were found to be independent of biomechanical factors.

Working with high workloads and/or deadline pressures is a relatively common work

demand and potential stressor within many professional jobs. Research findings show an

Table 1 continued

Reference Study population Study design Risk factor Findings

Smith et al. [79] Telecommunicationworkers (US)(n = 762)

Cross-sectional Exposure toelectronicperformance

monitoring

Greater prevalence ofreported symptomswith workers exposed

to EPM compared toworkers not exposed:81% monitoredworkers reported neckpressure compared to60%; 76% monitoredworkers reportedshoulder sorenesscompared to 57%, and43% of monitoredworkers reported lossof feeling in fingers/wrists compared to

27% with nonmonitored

Yun et al. [70] Bank VDU operators(South Korea)(n = 1,025)

Cross-sectional Hrs working withcomputer/day

Increased prevalence ofreported symptoms allareas with[4 hcomputer work/day

Abbreviations: BP = Blood Pressure; CAD = Computer Aided Design; CI = Confidence Interval;CWT = Colour Word Test; HR = Heart Rate; hrs = hours; LB = Low Back; Sh = shoulder; min. = minute;MS = musculoskeletal; OR = Odds Ratio; UE = Upper Extremity; VDU = Visual Display Unit; WMSDs =Work related musculoskeletal disorders

J Occup Rehabil (2007) 17:743765 751

13


10/24

increased risk of work related musculoskeletal symptoms when computer work is performed

under conditions where there are workload and/or deadline compliance pressures [4548] and

these results are summarised in Table 1. Bernard et al. [44] suggest the requirement to con-

sistently work to deadlines may increase both the biomechanical and psychological job

demands of computer work through responses such as increased typing speed with more

repetitive finger movements, longer periods in static postures, fewer rest breaks, increasedmusculoskeletal tension and greater psychological stress. There is evidence to support a

psychophysiological link between workload pressure and increased risk of musculoskeletal

symptoms. Wahlstrom et al. [78] found adding time pressure to a computer task resulted in

increased muscle activity in the trapezius muscle and forces applied to the mouse button. It is

argued prolonged and or excessive muscle tension or forces of application contribute to

biomechanical overload resulting in musculoskeletal skeletal symptoms or disorders [35].

Literature findings suggest the neck/shoulder area is especially vulnerable to the effects of

workload pressure. Hales et al. [46] reported a modest association between work pressure and

neck pain whilst Bernard et al. [44] found the number of hours worked under a deadline

amongst the newspaper employees, was an important predictor for neck pain.

Computerization of professional work tasks enables the implementation of an electronicperformance monitoring (EPM) system. Many professionals such as accountants and lawyers

are required to work with time costing systems which enable the organization to utilize

ongoing electronic performance monitoring. Some argue this can increase workload pressures

and work stressors [79]. Lawyers claim the daily billable targets established by their organi-

zation may require longer work hours in order to meet or exceed these targets with resultant

increased work stress [80]. The lawyers described the system as the corporate equivalent of

Chinese water torture with every minute of their work day being electronically monitored and

this scrutiny adds to the stressors already present within their job. EPM is also used with semi-

skilled occupations and Smith et al. [79] found its use increased the levels of reported stress

and musculoskeletal symptoms amongst telecommunication workers. Of the workers moni-

tored by EPM, 49% reported wrist symptoms, 82% reported neck symptoms and 79% reportedshoulder soreness, compared to 26, 58 and 54% respectively in non-monitored workers.

There is evidence that computerization of work may have the effect of increasing workload,

time, deadline and performance pressures. As a result, workers may be required or encouraged

to work longer hours and at an increased pace, and/or react with an increased stress response. It

is suggested that when these factors are combined with the existing biomechanical demands

associated with computer based work, there can be an interactive effect and compound the risk

of work related musculoskeletal symptoms and disorders.

Working with Heightened Muscle Tension and Forces

The normal physiological response to stress is an activation of the autonomic and central

nervous systems. This will result in secretion of catecholamines (adrenalin and noradrenalin),

corticosteroids (cortisol), and increased activity in the muscle tone regulatory system (reticular

formation). Depending on the individual level of physiological reactivity to the stressor, there

will be an increased activation of muscles, an increase in heart rate and blood pressure, with

arteriolar vasoconstriction reducing nutrient delivery to soft tissues. Working with a sustained

and heightened level of muscle activity exceeding what is required to perform a motor task,

will increase the biomechanical loading associated with this activity. It is argued that there is a

sufficient body of scientific evidence to demonstrate a biological relationship between the

752 J Occup Rehabil (2007) 17:743765

13


11/24

physiological stress responses affecting the musculoskeletal system, and the development of

work related musculoskeletal symptoms or disorders [31].

The literature has identified a number of keyboard or mousing techniques and postural

reactivity to work demands or psychosocial stressors, which may contribute to an increased

risk of musculoskeletal symptoms with computer work. They include working with heightened

muscle tension [37, 57, 82], applying increased forces to the keyboard or mouse [58, 83, 84],or working with an increased speed of mouse click [85]. Findings from relevant studies are

summarised in Table 2. It is suggested that a person may develop a relatively stable method or

style of working over a period of time and as a consequence of individual characteristics and/or

social learning, may be predisposed to additional risk of musculoskeletal symptoms within

their job [86].

Professional work is generally characterised by greater cognitive demands when compared

to semi-skilled office occupations. A number of studies have demonstrated increased muscle

activity occurs in the trapezious muscle in the neck/shoulder area when experimentally

induced mentally demanding work is added to a computer entry task [15, 52, 87, 88]. Some

studies have demonstrated an interactive effect between biomechanical and psychological

loading and suggest psychophysiological mechanisms for musculoskeletal symptoms, partic-ularly in the neck area [88]. Pre-existing static and low-level muscle activation associated with

computer work may tend to interact with and be compounded by a heightened psychophysi-

ological response when a mentally demanding task is added, resulting in additional muscle

activation. Waersted and Bjorklund [89] refer to a psychogenic muscle tension response to

increased psychological demands, where predominantly increased static loading occurs in

shoulder muscles independent of postural demands with work such as computer based task.

Larsson et al. [49] found that the addition of a mentally demanding task to static loading

conditions increased trapezius (neck) muscle activation by approximately 20%.

It has been demonstrated with industrial workers that the risk of developing musculoskeletal

symptoms is substantially increased when excessive force is combined with a repetitive

activity [90, 91]. Feuerstein et al. [92] argue the application of more force than is necessary forkeyboard or mouse activation contributes to the exacerbation and maintenance of musculo-

skeletal symptoms. In a case-controlled study with symptomatic office workers, researchers

found that the force exerted on the keys was a more important factor than degree of repetition,

and that the mean key activation force was between 4 and 5 times greater than the force

necessary to activate a key. Significantly higher forces were measured for those that performed

more than 4 h computer work per day compared to a control group. In an earlier study, Martin

et al. [59] compared electromyography (EMG) readings in the forearm muscles with keyboard

reaction forces. They found there was a tendency for keyboard users to depress the keys with

over 5 times the necessary activation force and the highest absolute force was exerted by the

thumb on the space bar.

Wahlstrom et al. [78] measured the physiological effect of time pressure in the first dorsalinterosseus, extensor digitorum and trapezius muscles in the right arm with computer mouse

activity using electromyography. This controlled trial compared the physiological response

between performing the same computer task with no time constraint and then with instructions

to work as fast as possible with time constraints. They found increased physiological

activity when participants were required to work under time pressure. This included increased

muscle activity, peak forces applied to the mouse button, heart rate and blood pressure. In a

study with assembly plant workers it was found that a requirement to perform repetitive work

at a faster pace, was accompanied by increased forces and higher muscle tension was in the

hands and arms. It was concluded that this individual reaction to time pressure was a risk factor

for work related musculoskeletal symptoms [93].

J Occup Rehabil (2007) 17:743765 753

13


12/24

Table 2 Studies of the relationship between mental work demands, heightened muscle tension, forces and riskof musculoskeletal symptoms with computer work

Reference Study population Study design Intervention or riskfactor

Findings

Birch et al.

[15]

Female CAD

Operators(Denmark)(n = 14)

Repeated

measures

Time pressure, mental

demand andprecisionintervention addedto standardisedcomputer task ineight randomexposurecombinations

Higher EMG activity for

all muscles tested(trapezious,infraspinatus, deltoid &ext. digitorum) withhigh time pressure (+low precision + lowmental demands). Noeffect with high mentaldemand, yetproductivity reduced

Ekberg et al.[87]

Female VDUWorkers (Sweden)(n = 20)

Repeatedmeasures

Mentally stressfultasks added to dataentry; mental

arithmetic andmodified CW(colour word) test

Increased EMG activitywith significantly largeinter-individual

variations

Feuerstein

et al. [58]

Symptomatic office

workers (US)(n = 48)

Case-controlled Keyboard force and

keying ratemeasured during15 min

keyboarding task

Higher keyboard forces

(45 times greater thanactivation force) forworkers with more

severe symptoms. Nocorrelation observed

with keying rate

Larsson et al.[49]

Female hospitalworkers (Sweden)(n = 20)

Repeatedmeasures

Static loading oftrapezius and thencombined with

mentallydemanding tasks(CW task)

Approx. 20% increaseEMG activity intrapezius muscle when

mental stress added tostatic loading

Lundberget al. [52]

Female cash registeroperators (62) anduniversity students(20) (Sweden)

Repeatedmeasures

Combination ofmental stressors(Stroop CWT andmental arithmetic)and physical loadwith standardisedcomputer task

Significant increase intrapezius muscleactivity with mentalstressors with evidenceof synergist effectwhen CWT added tophysical load (ie incr.in EMG activitysignificantly greaterwith combination than

when each one alone isadded)

Macaulay [85] University students(UK) (n = 60)

Randomisedcontrolled trial

Cognitive activityincluding testfollowing tutorialwith computer

Increased speed of mouseclick with experimentalgroup. No associationwith anxiety measures

Martin et al.[59]

University studentsand staff (US)(n = 10)

Case-controlled Keyboard reactionforces measuredduring keyboardtask

Large variability in peakreaction forces withsome exerting

[5 times force neededto depress key. Higherforces with space bar.

754 J Occup Rehabil (2007) 17:743765

13


13/24

Working with higher muscular activity than is needed for the performance of a task will

increase biomechanical loading, additional to the loading already associated with a job. In

the case of computer based work, this behaviour or workstyle may persist over a number ofhours, days or weeks resulting in potential cumulative overload and subsequent increased

risk of musculoskeletal symptoms or disorders. Various pathomechanisms have been

suggested to provide an explanation for this increased risk of symptoms when work is

performed in the presence of heightened muscle tension and/or forces. These include

biomechanical overload and potential cumulative harm to tendons and muscles; accumula-

tion of metabolites as a consequence of reduced circulation [62]; interference with repair

mechanisms [24, 94]; pain related to hypoxia, ischaemia or the metabolic effects of energy

deficit of muscle cells, accumulation of calcium in muscle which damages cells, or alteration

of the biomechanical composition of the muscle interstitium to a level where nociceptors are

activated [94].

Experimental studies have demonstrated that when psychological demands such as mentallydemanding work and high concentration is combined with computer work, there is a tendency

to work with heightened muscle tension and/or application forces to the keyboard or mouse.

This has been identified as a risk factor for work related musculoskeletal symptoms and has

significant relevance for office based professional occupations. These occupations are typically

characterised by higher psychological demands and when combined with the added biome-

chanical demands associated with more computer aided work within their job, the potential

interactive effect of these risk factors may need greater consideration by organizations.

Working with Inadequate Breaks

Professional workers generally have greater job control than semi-skilled office workers [39]

and therefore it is reasonable to assume they are more able to take discretionary work breaks

from prolonged periods of computer based work. Adequate work breaks have been identified

as beneficial for health and wellbeing within a computerized work environment and in some

places are governed by occupational health and safety regulations. In South Korea, a 10 min

break per 50 min of computer work is required within all workplaces, although observations of

work practices suggest this often does not occur in practice [70]. Bergqvist et al. [23], found

reported limited rest break opportunity with computer work resulted in increased odds ratios

for musculoskeletal symptoms in most upper body areas surveyed, particularly tension neck

syndrome where the results suggested there was a strong increased risk of reported problems.

Table 2 continued


Findings

Waersted andWestgaard

[88]

Students (Norway)(n = 37)

Repeatedmeasures

Adding attention-related activities

to computer taskwith low levelphysical activity

Increased EMG activity,more prevalent in the

frontalis and uppertrapezius muscles

Wahlstrom

et al. [78]

Various occupations

(Sweden) (n = 15)

Repeated

measures

Adding time pressure

to computer task

Increased EMG activity,

force applied to mousebutton, BP and HR

For notes, see Table 1

J Occup Rehabil (2007) 17:743765 755

13


14/24

Work breaks enabling movement away from sitting at a computer workstation can address

the biomechanical risk factors with computer work through variation in muscle activity,

reduced periods of static loading to postural muscles, and shorter duration of repetitive work

cycles [12, 95]. In contrast to rest breaks, it is thought work breaks that address the postural

fixity and biomechanical inactivity which occurs with computer work is of greater impor-

tance than factors such as working posture [35].An often overlooked benefit of work breaks is that they may also reduce the risks associated

with the psychological demands and stressors with computer work. This may be particularly

relevant to professional occupations characterized by more mentally demanding work with

sustained periods of concentration and attention to a task. The National Institute for Working

Life in Sweden recommends work breaks during computer work should be used to talk to a

co-worker or clear out your head in a quiet place and .the more stressful, your work is, the

more often and for longer periods you should do this [ 96]. Oberlechner and Nimgade [41]

found in their study with financial traders, encouragement of traders to take downtime in

order to relax and be noisy was important for the management of stress within their job.

Adequate rest and recovery breaks are considered as important for reversing the state of

psychophysiological arousal and muscle tension that may develop under stressful workconditions [36].

It has also been argued that computerization of an office work environment may adversely

affect social interaction by isolating work to the computer workstation and separating it from

the usual social environment [9, 14]. This may reduce access to social support mechanisms, an

important buffer between job stressors and worker stress [18]. Toomingas et al. [97] found the

strongest and most consistent association between psychosocial factors and reported neck and

low back musculoskeletal symptoms, occurred in conditions of low social support and high

mental demands. It is suggested that social interaction with work colleagues may be limited by

the availability of work breaks and social support is more difficult to access when there are

inadequate breaks away from the computer workstation due to high workload demands.

As demonstrated by literature findings summarised in Table 3, there is considerable vari-ation in the work break interventions used in the experimental studies identified. The majority

of studies have also focused on the management of the biomechanical risk factors with

computer work and involved semi-skilled occupations. Little research appears to have been

directed towards evaluating the effect of altering work break behaviour for management of the

interrelationship between biomechanical and psychosocial risk factors associated with com-

puter work.

Work break interventions studied have included rest or passive breaks, activity and/or

exercise or stretching breaks, and scheduled or discretionary breaks. They also vary in duration

and frequency, ranging from frequent micro-pauses of a few seconds to less frequent longer

breaks of up to 10 min in duration. However, few studies have attempted to match work break

protocol to the varying biomechanical and psychological demands of a job, especially inrelation to computer based occupations. Winkel and Oxenburgh [98] argue that work break

activity with computer work needs to involve meaningful tasks that can be integrated into

normal work practices and involve biomechanical variation.

Studies comparing active work breaks with passive breaks have found increased

preference by workers for active breaks with mixed results on their effectiveness for reducing

the risk of musculoskeletal symptoms [99, 100]. Sundelin and Hagberg [101] compared the use

of passive and active work pauses on neck and shoulder EMG activity and reported

discomfort with computer work. They found active pauses were preferred to passive pauses by

the participants and they argued that the change in muscle activity resulting from active pauses

was important for management of the static loading biomechanical risk factors.

756 J Occup Rehabil (2007) 17:743765

13


15/24

Table 3 Studies of the relationship between work break behaviour and risk of musculoskeletal symptoms withcomputer work


Findings

Bergqvist

et al. [23]

VDU work incl.

numerical input,data accessing,word processing(Sweden)(n = 260)

Cross-sectional Limited rest break

opportunity

For limited rest break

opportunity: incr. risk oftension neck syndrome(OR = 7.4: 95% CI:3.117.4); neck/shoulder discomfort(OR = 2.7; 95% CI:1.25.9) and any arm/hand diagnosis(OR = 2.7; 95% CI:0.89.1)

Fenety andWalker[105]

Directory assistanceoperators (US)(n = 11)

Prospective cohort Passive stretchingexercises

Increase in discomfortduring test period,although curbed by

exercise intervention.Two operators reportedwrist discomfort withstretching exercise.

Ferreira et al.[103]

Call-centre workers(Brazil) (n = 106)

Retrospectiveover 30 month

period

10 min break everyhour

Reduction in reportedmusculoskeletal

symptoms

Galinsky et al.[100]

Data entry operatorsfrom IRS (US)(n = 42)

Repeatedmeasures

Supplementary 5 minbreak every hr

Reduced symptoms withintervention group forall body areas

Encouraged activebreaks

Significant reduction insmall day-to-day

increases in rightforearm, wrist and handdiscomfort

Henning et al.[99]

Insurance claimprocessors (US)

(n = 92)


Four additionalbreaks/hr (3 9 30 s

and 1 9 3 min) fortwo experimentalgroups. Stretchingexercises added toone of these groups

No effect with additionalshort duration work

breaks on upper bodydiscomfort

Active work breakspreferred to passive

Karlqvist et al.[55]

VDU workers from 46different worksitesand range of

occupations(Sweden)(n = 1,529)

Cross-sectional Working[2 hwithout break

Increased prevalence ofsymptoms in all upperbody areas

McLean et al.[102]

Data entry and wordprocessingoperators (Canada)(n = 15)


Three microbreakprotocols:discretionary; 30 severy 20 min; 30 severy 40 min

Reduced discomfort scoreswith additionalmicrobreaks, especiallywhen taken every20 min

J Occup Rehabil (2007) 17:743765 757

13


16/24

Other studies have examined the effectiveness of pause or micro breaks, arguing short

frequent breaks are needed to enable changes in motor unit activity in postural muscles and

allow musculoskeletal recovery [99]. McLean et al. [102] found no statistically significant

association between muscle cyclic behaviour and reported discomfort in 15 data entry and

work processing operators, when prompted to take a scheduled 30 s break every 20 min andthen every 40 min. Yet in this small study, participants did report reduced discomfort when

schedules microbreaks were taken. There is some evidence that frequent short breaks may be

disruptive and a potential psychological stressor for some workers. Sundelin and Hagberg

[101] found frequent work pauses were regarded by participants as disturbing to work routines,

a finding which may be relevant to professional occupations where sustained periods of

concentration are often required.

Longer duration work breaks have been found to reduce the risk of musculoskeletal

symptoms and disorders. In a retrospective study completed with Brazilian call centre workers,

it was found that the introduction of a 10 min rest break for every hour of work reduced the

risk of musculoskeletal disorders [103]. They also concluded that this intervention was more

Table 3 continued


Findings

Sundelin andHagberg

[101]

Word processoroperators (Sweden)

(n = 12)

Repeatedmeasures

Compared active(with stretching),

passive (rest only)and diverting (leftdesk to walk intocorridor)

Breaks with activitypreferred

EMG readings of trapeziusmuscle demonstratedchange in habitualmuscle activity pattern

with active pauses

Winkel andOxenburgh[98]

Data entry operators(accounts dept)(Sweden) (n = 45)

Repeatedmeasures

Able to vary betweensitting and standingto perform work

Active work breaks moreeffective than inactive

Yun et al. [70] Bank VDU operators(South Korea)(n = 1,025)

Cross-sectional More than 10 min ormore break withinevery hour ofcomputer work

Increased prevalence ofreported MS symptomsin all areas for those thatdid not take mandatory

break. With breaks:17.6% reported necksymptoms compared to39.2% without breaks;27.5% reportedshoulder symptomscompared to 52.8%without breaks, 13.7%

reported wristsymptoms compared to

22.2% without breaks,21.6% reported upperback symptoms

compared to 31.9%without breaks and19.6% reported lowerback symptomscompared to 39.6%without breaks

For notes, see Table 1

758 J Occup Rehabil (2007) 17:743765

13


17/24

effective than other risk reduction inventions including workstation design, work posture and

stretching.

The effectiveness of incorporating stretching exercises during work breaks has been

examined in a number of studies [104, 105], with no strong evidence that stretching reduces

the risk of musculoskeletal symptoms. However, a significant limitation of these studies is

related to often poor compliance of study participants with the experimental intervention.Monsey et al. [106] stated that factors affecting compliance with stretching exercises included

lack of immediate benefits, lack of time and lack of recall of exercises. Henning et al. [99]

found on average only 45.08% of participants complied with the stretching protocol in their

study and proposed the reported task disruption that occurs with frequent, short duration

scheduled work breaks may have been a contributing factor to this lack of compliance. Winkel

and Oxenburgh [98] excluded what are termed as pause gymnastics from their study with

data entry operators, claiming employees usually give up on these exercises as they are not

meaningful to their daily work. They felt changes in work organization enabling increased

work breaks was more important for reducing neck/shoulder discomfort with computer based

work than other factors, including workstation redesign.

The literature supports the use of active work breaks for the reduction in the risk ofmusculoskeletal symptoms. Mathiassen [12] argues the significance of breaks is more related

to the opportunity for variation in job demand exposure, including both biomechanical and

mental variation [9, 107], rather than the contents of rest itself. There appears scarcity of

research on the use of work breaks for the management of the psychological demands and

stressors within a job and associated risk factors. Professional occupations may have a

greater need for systems of work that enable and encourage healthy work break behaviours

than is generally recognised and more research in this area would be beneficial to identify

what work break practices should be facilitated by organizations within their office work-

places. Although it can be argued professional workers are generally more able to utilise

discretionary breaks as they tend to have greater job control, organizational factors such as

workload demands and productivity requirements may discourage effective work breakbehaviours.

Discussion

Computerization of the office work environment amongst professional occupational groups

appears to have significantly changed the way their work is organised and performed. Whereas

semi-skilled occupations have typically worked with an office tool such as a typewriter or

accounting machine for decades, office based professional workers have tended to be limited to

much more basic tools such as a pen, pencil and telephone. With the understanding that this

change has increased efficiencies and capabilities of their work, there is also evidence that theconsequences may include factors such as increased workloads, added time and performance

monitoring pressure, greater information processing, memory and multi-tasking demands. It is

argued these factors have added to the existing biomechanical and psychological demands with

office based work amongst professional occupational groups, and has also introduced new

psychosocial stressors. Whilst the risk factors for work related musculoskeletal symptoms with

computer work have been extensively researched and are generally well established, most

studies have involved semi-skilled occupations. Although the biomechanical demands may be

similar to professional occupations, the varied job characteristics between these occupational

groups result in different types and levels of psychological demands and psychosocial

stressors. Therefore the results from studies with semi-skilled occupations may only be

J Occup Rehabil (2007) 17:743765 759

13


18/24

partially transferable to professional workers. It is argued the rapid progression of comput-

erized work tasks within office based professional occupations warrants more research

specifically with these groups.

The decision to introduce or extend the computerization of professional work tasks into an

office work environment are generally made by the organization and is usually done for valid

or essential reasons including increased efficiency of work processes, necessitated by acompetitive commercial market. Whilst these changes are often welcomed by workers, the

additional risk factors for musculoskeletal symptoms or disorders introduced through the

interaction and/or combination between the biomechanical demands, psychological demands

and psychosocial stressors associated with computer work should also be recognised, measured

and controlled. It is proposed that there is an interactive relationship between these risk factors,

with a potential synergist effect. That is the risk of work related musculoskeletal symptoms

with a combination of these risk factors is greater than the sum of each one alone. For example,

the introduction of a work system change, such as the requirement to learn how to use a new

software system or work to a more precise electronic monitoring system, may result in

increased cognitive demands and/or psychosocial stressors, which may interact and combine

with existing biomechanical risk factors for musculoskeletal disorders. Depending on anindividuals coping mechanisms for these work system changes, a worker may respond in a

potentially harmful way, such as: working with heightened muscle tension, increasing work

pace and/or forces, taking fewer work breaks or remaining in static work postures for longer

periods. These behaviours may prolong or augment any existing muscle tension associated

with the computerized work activity. The progression towards muscle fatigue and over-

whelming of the normal ongoing reparative ability of the musculoskeletal system, resulting in

cumulative microtrauma, has been suggested as a potential pathophysiological mechanism for

the development of symptoms and/or disorder [108].

It is also suggested that work demands and/or psychosocial stressors characteristic within

professional occupational groups such as workload, deadline and performance pressures, may

exacerbate or encourage work behaviours and responses that further heighten the risk factorsfor work related musculoskeletal symptoms. Literature search results have demonstrated that

working long hours with a computer, with inadequate breaks, at an increased work pace, and/or

with heightened muscle tension or excessive application forces to the keyboard or mouse, are

all factors that may further increase the risk of the development, exacerbation or maintenance

of musculoskeletal symptoms with computer based work.

This paper has attempted to highlight the need for organizations to consider and address the

potential biomechanical and psychosocial hazards associated with the expansion or upgrading

of computerized work tasks amongst their professional staff. By recognition of the potential

adverse effect on existing biomechanical and psychological risk factors with computer work,

strategies to moderate or buffer these effects can be considered and implemented. Based on the

literature findings within this paper, the establishment of a work environment that enables andpromotes reasonable work hours, realistic workload, deadline and performance monitoring

expectations, and adequate work break opportunity may be an effective means of controlling

higher risk work behaviours and physiological responses when performing computer based

work. Whilst individual factors such as age, gender, personality, and biomechanical charac-

teristics are also recognised as valid contributors to the risk of musculoskeletal symptoms

with computer work, the power to manage how work is organised is generally within the

hands of an organization [1]. Effective risk management for the prevention of work related

disease or injury requires an environmental approach, creating a work environment which can

accommodate the risk factors introduced into the work system and provide pre-event inter-

vention measures [109].

760 J Occup Rehabil (2007) 17:743765

13


19/24

Whilst workstation ergonomics has not been addressed in this paper, it continues to be

considered as important for reduction in risk of musculoskeletal symptoms with computer

work. Yet occupational disease statistics tend to show that although there have been improved

ergonomic conditions in offices, there has been no significant decrease in reported work related

musculoskeletal disorders [37]. Swedish statistics demonstrate the reported cases of muscu-

loskeletal illness where computer work was given as the reason for the illness, increased by20% between 1992 and 1998 [84]. There is now growing evidence that the psychosocial risk

factors within a computerized work environment may be at least as important as other factors

[33] and ergonomic risk factors are of less significance than previously assumed [ 76].

In conclusion, computer technology will continue to improve productivity and performance

within offices with many benefits to both employers and employees and it has not been the

purpose of this paper to critically address these developments. As was recently observed by a

young accountant, computer functions now do the grunt work, freeing these professionals

from paper ledgers and endless documentation [110]. Effective management of occupa-

tional health risks is more effective when risk factors generated by a changing work

environment and the organization of how work is done, are recognised, measured and con-

trolled in order to minimize the incidence of WMSDs. It is argued more research is required toidentify and measure the risk factors for musculoskeletal symptoms specifically for profes-

sional occupations who work in a computerized work environment, this includes the

interactive or synergist effect on the level of risk between all biomechanical and psychological

demands and stressors. This should also include a measure of the how organizational factors

common to professional workplaces may encourage, exacerbate and maintain individual work

behaviours and reactivity to work demands and stressors, which may compound existing risk

factors for musculoskeletal symptoms found to be present within a computerized work

environment.

References

1. Harenstram A, Staffan M, Bernston E, Bolin M, Ylander J. Understanding the organisational impact onworking conditions and health. Stockholm: National Institute for Working Life; 2006.

2. US Census Bureau (2005). Computer and Internet use in the United States: 2003.http://www.census.gov/prod/2005pubs/p23-208.pdf2005 . Accessed 22 Mar 2007.

3. Hjelm E, Karlkvist L, Hagberg M, Risberg E, Isaksson A, Toomingas A. Working conditions and mus-culoskeletal disorders amongst male and female computer operators. In: IEA 2000/HFES 2000Conference; 2000.

4. Aborg C, Billing A. Health effects of the paperless officeevaluations of the introduction of electronicdocument handling systems. Behav Inf Technol 2003;22(6):38996.

5. Carayon P, Smith MJ. Work organization and ergonomics. Appl Ergon 2000;31(6):64962.

6. Amick BC, Smith MJ. Stress, computer-based work monitoring and measurement systems: a conceptualoverview. Appl Ergon 1992;23(1):616.

7. Cooper CL, Cox A. Occupational stress among word process operators. Stress Med 1985;1:8792.8. Smith B, Cohen B, Stammerjohn LW. An investigation of health complaints in job stress in video display

operations. Hum Factors 1981;23(4):387400.9. Hockey GR, Briner RB, Tattersall AJ, Wiethoff M. Assessing the impact of computer workload on

operator stress: the role of system controllability. Ergonomics 1989;32(11):140118.10. Feuerstein M. Workstyle: definition, empirical support, implication for prevention, evaluation, and reha-

bilitation of upper-extremity disorders. In: Moon SD, Sauter SL, editors. Beyond biomechanics:psychosocial aspects of musculoskeletal disorders in office work. London: Taylor & Francis; 1996. p. 177206.

11. Waersted M, Westgaard RH. An experimental study of shoulder muscle activity and posture in a paperversion versus a VDU version of a monotonous work task. Int J Ind Ergon 1997;19:17585.

J Occup Rehabil (2007) 17:743765 761

13
http://www.census.gov/prod/2005pubs/p23-208.pdf2005http://www.census.gov/prod/2005pubs/p23-208.pdf2005


20/24

12. Mathiassen SE. Diversity and variation in biomechanical exposure: What is it, and why would we like toknow? Appl Ergon 2006;37:41927.

13. Howell WC. Engineering psychology in a changing world. Annu Rev Psychol 1993;44:23163.14. Smith M. Psychosocial aspects of working with video display terminals (VDTs) and employee physical

and mental health. Ergonomics 1997;40(10):100215.15. Birch L, Juul-Kristensen B, Jensen C, Finsen L, Christensen H. Acute response to precision, time pressure

and mental demand during simulated computer work. Scand J Work Environ Health 2000;26(4):299305.

16. Dux PE, Ivanoff J, Asplund CL, Marois R. Isolation of a central bottleneck of information processing withtime-resolved MRI. Neuron 2006;52:110920.

17. Dainoff MJ. Occupational stress factors in visual display terminal (VDT) operations: a review of empiricalresearch. Behav Inf Technol 1982;1(2):14176.

18. Yang C, Carayon P. Effect of job demands and social support on worker stress: a study of VDT users.Behav Inf Technol 1995;14(1):3240.

19. Johansson G, Aronsson G. Stress reactions in computerized administrative work. J Occup Behav1984;5:159181.

20. Smith M. Mental and physical strain at VDT workstations. Behav Inf Technol 1987;6(3):24355.21. Attwood D. Comparison of discomfort experienced at CAD, word processing and traditional drafting

workstations. Int J Ind Ergon 1989;4:3950.22. Kamwendo K, Linton SJ, Moritz U. Neck and shoulder disorders in medical secretaries. Part I. Pain

prevalence and risk factors. Scand J Rehabil Med 1991;23(3):12733.

23. Bergqvist U, Wolgast E, Nilsson B, Voss M. Musculoskeletal disorders among visual terminal workers:individual, ergonomic and work organizational factors. Ergonomics 1995b;38(4):76376.

24. Punnett L, Bergqvist U. Visual display unit and upper extremity musculoskeletal disorders: a review ofepidemiological findings. Solna: National Institute for Working Life; 1997.

25. Aaras A, Horgen G, Ro O. Work with the visual display unit: health consequences. Int J Hum ComputInteract 2000;12(1):10734.

26. Kryger AI, Andersen JH, Lassen CF, Brandt LPA, Vilstrup I, Overgaard E, Thomsen JF, Mikkelsen S.Does computer use pose an occupational hazard for forearm pain; from the NUTATA study. OccupEnviron Med 2003;60:11.

27. Hagberg M, Wegman DH. Prevalence rates and odds ratios of shoulder-neck disease in different occu-pational groups. Brit J Ind Med 1987;44:60210.

28. Hagberg M, Silverstein B, Wells R, Smith M, Hendrick H, Carayon P, Perusse M. Work related mus-culoskeletal disorders. London: Taylor & Francis; 1995.

29. Bernard BP. Musculoskeletal disorders and workplace factors: a critical review of epidemiological evi-dence for work-related musculoskeletal disorders of the neck, upper extremity, and low back. Cincinnati:US Department of Health and Human Services; 1997. Report No.: Publication No 97-141.

30. Devereux IG, Buckle P. Adverse work stress reactionsa review of the potential influence on work related

musculoskeletal disorders (WMSDS). In: Proceedings of the IEA 2000/HFES 2000 Congress; 2000; p.45760.

31. Aptel M, Cnockaert JC. Stress and work-related musculoskeletal disorders of the upper extremities. TUTBNewsletter 2002;September:505.

32. Bongers PM, Kremer AM, ter Laak J. Are psychosocial factors, risk factors for symptoms and signs of the

shoulder, elbow, or hand/wrist?: a review of the epidemiological literature. Am J Ind Med 2002;41:31542.33. Pransky G, Robertson MM, Moon SD. Stress and work-related upper extremity disorders: implications for

prevention and management. Am J Ind Med 2002;41:44355.34. Ariens GAM, van Mechelen W, Bongers PM, Bouter LM, van der Wal G. Psychosocial risk factors for

neck pain: a systematic review. Am J Ind Med 2001;39:18093.

35. Winkel J, Westgaard R. Occupational and individual risk factors for shoulder-neck complaints: Part II thescientific basis (literature review) for the guide. Int J Ind Ergon 1992;10:85104.

36. Lundberg U. Psychophysiology of work: stress, gender, endocrine response, and work-related upperextremity disorders. Am J Ind Med 2002;41:38392.

37. Melin B, Lundberg U. A biopsychosocial approach to work-stress and musculoskeletal disorders. J Psy-chophysiol 1997;11:23847.

38. Hanse JJ. The impact of VDU use and psychosocial factors at work on musculoskeletal shoulder symptomsamong white-collar workers. Work Stress 2002;16(2):1216.

39. Karasek R, Theorell T. Healthy work. Stress, productivity, the reconstruction of working life. US: BasicBooks; 1990.

40. Carayon P. Stressful jobs and non-stressful jobs: a cluster analysis of office jobs. Ergonomics1994;37(2):31123.

762 J Occup Rehabil (2007) 17:743765

13


21/24

41. Oberlechner T, Nimgade A. Work stress and performance among financial traders. Stress Health2005;21:28593.

42. Wallace JE. Work-to-nonwork conflict among married male and female lawyers. J Organiz Behav1999;20(6):797816.

43. Zapf D. Emotion work and psychological well-being. A review of the literature and some conceptualconsiderations. Hum Resources Manag Rev 2002;12(2):23768.

44. Bernard B, Sauter S, Fine L, Petersen M, Hales T. Job task and psychosocial risk factors for work-related

musculoskeletal disorders among newspaper employees. Scand J Work Environ Health 1994;20:41726.45. Bongers P, de Winter CR, Kompier MAJ, Hildebrandt VH. Psychosocial factors at work and musculo-

skeletal disease. Scand J Work Environ Health 1993;19:297312.46. Hales TR, Sauter SL, Peterson MR, Fine LJ, Putz-Anderson V, Schleifer LR, Ochs TT, Bernard BP.

Musculoskeletal disorders among visual display terminal users in a telecommunications company. Ergo-nomics 1994;37(10):160321.

47. Polanyi MFD, Cole DC, Beaton DE, Chung J, Wells R, Abdolell M, Beech-Hawley L, Ferrier SE,Mondloch M, Shields SA, Smith JM, Shannon HS. Upper limb work-related musculoskeletal disorders

among newspaper employees: cross sectional survey results. Am J Ind Med 1997;32:6208.48. Huang GD, Feuerstein M, Kop WJ, Schor K, Arroyo F. Individual and combined impacts of biomechanical

and work organization factors in work-related musculoskeletal symptoms. Am J Ind Med 2003;43:495506.

49. Larsson S, Larrson R, Zhang Q, Cai H, Oberg PA. Effects of psychophysiological stress on trapezius

muscles blood flow and electromyography during static load. Eur J Appl Physiol 1995;71:4938.50. Houtman ILD, Bongers PM, Smulders PGW, Kompier MAJ. Psychosocial stressors at work and muscu-

loskeletal problems. Scand J Work Environ Health 1994;20:13940.51. Fredriksson K, Alfredsson L, Koster M, Thorbjornsson CB, Toomingas A, Torgen M, Kilbom A. Risk

factors for neck and upper limb disorders: results from 24 years of follow up. Occup Environ Med1999;56:5966.

52. Lundberg U, Kadefors R, Melin B, Palmerud G, Hassmen P, Engstrom M, Dohns IE. Psychophysiologicalstress and EMG activity of the trapezius muscle. Int J Behav Med 1994;1(4):35470.

53. Linton S. Risk factors for neck and back pain in a working population in Sweden. Work Stress1990;4(1):419.

54. Devereux IG, Vlachonikolis PW, Buckle PW. Epidemiological study to investigate potential interactionbetween physical and psychosocial factors at work that may increase the risk of symptoms of musculo-skeletal disorder of the neck and upper limb. Occup Environ Med 2002;59(4):26977.

55. Karlqvist L, Tornqvist EW, Hagberg M, Hagman M, Toomingas A. Self-reported working conditions ofVDU operators and associations with musculoskeletal symptoms: a cross-sectional study focusing ongender differences. Int J Ind Ergon 2002;30(45):27794.

56. Feuerstein M, Nicholas RA, Huang GD, Haufler AJ, Pransky G, Robertson M. Workstyle: development of

a measure of response to work in those with upper extremity pain. J Occup Rehabil 2005;15(2):87104.57. Smith MJ, Carayon P. Work organization, stress, cumulative trauma disorders. In: Moon SD, Sauter SL,

editors. Beyond biomechanics. Psychosocial aspects of musculoskeletal disorders in office work. London:Taylor and Francis; 1996.

58. Feuerstein M, Armstrong T, Hickey P, Lincoln A. Computer keyboard force and upper extremity symp-

toms. J Occup Environ Med 1997;39(12):114453.59. Martin BJ, Armstrong TJ, Foulke JA, Natarajan S, Klinenberg E, Serina E, Rempel D. Keyboard reaction

force and finger flexor electromyograms during computer keyboard work. Hum Factors 1996;38(4):65464.60. Marcus M, Gerr F. Upper extremity musculoskeletal symptoms among female office workers: associations

with video display terminal use and occupational psychosocial stressors. Am J Ind Med 1996;29(2):16170.

61. Larsman P. On the relation between psychosocial work environment and musculoskeletal symptoms.Stockholm: Department of Psychology, Goteborg University; 2006.

62. Armstrong TJ, Buckle P, Fine LJ, Hagberg M, Jonsson B, Kilbom A, Kuorinka I, Silverstein BA, SjogaardG, Viikari-Juntura E. A conceptual model for work-related and upper-limb musculoskeletal disorders.Scand J Work Environ Health 1993;19:7384.

63. Rosenthal JA. Qualitative descriptors of strength of association with effect size. J Soc Sci Res1996;21(4):3759.

64. Australian Bureau of Statistics. Were living longer, working harder and using more energy: ABS: Aus-tralian Bureau of Statistics; 2006. Report No.: 4102.0.

65. Weston R, Gray M, Stanton D. Long work hours and the wellbeing of fathers and their families: AustralianInstitute of Family Studies; 2004.

66. Urbis Keys and Young. The Solicitors of New South Wales in 2015. Sydney: The Law Society of NewSouth Wales; 2006.

J Occup Rehabil (2007) 17:743765 763

13


22/24

67. Dembe AE, Erickson JB, Delbos RG, Banks SM. The impact of overtime and long work hours onoccupational injuries and illnesses: new evidence from the United States. Occup Environ Med2005;62:58897.

68. Haufler AJ, Feuerstein M, Huang GD. Job stress, upper extremity pain and functional limitations insymptomatic computer users. Am J Ind Med 2000;38:50715.

69. Blatter BM, Bongers PM. Duration of computer use and mouse use in relation to musculoskeletal disordersof neck or upper limb. Int J Ind Ergon 2002;30:295306.

70. Yun M, Lee YG, Eoh HJ, Lim SH. Results of a survey on the awareness and severity assessment of upper-limb work-related musculoskeletal disorders among female bank tellers in Korea. Int J Ind Ergon2001;27:34757.

71. Jensen C, Finsen L, Sogaard K, Christensen H. Musculoskeletal symptoms and duration of computer andmouse use. Int J Ind Ergon 2002;30(45):26575.

72. Lassen C, Mikkelsen S, Kryger AI, Brandt LPA, Overgaard E, Thomsen JF, Vilstrup I, Andersen JH.

Elbow and wrist/hand symptoms among 6,943 computer operators: a 1-year follow-up study (The NU-DATA Study). Am J Ind Med 2004;46:52133.

73. Leroyer A, Edme J, Vaxevanoglou X, Buisset C, Laurent P, Desobry P, Frimat P. Neck, shoulder, and handand wrist pain among administrative employees: relation to work-time organization and psychosocialfactors at work. J Occup Med 2006;48(3):32633.

74. Palmer KT, Cooper C, Walker-Bone H, Syddall H, Coggon D. Use of keyboards and symptoms in the neckand arm: evidence from a national survey. Occup Med 2001;51(6):3925.

75. Nakazawa T, Okubo Y, Suwazono Y, Kobayashi E, Komine S, Kato N, Nogawa K. Association betweenduration of daily VDT use and subjective symptoms. Am J Ind Med 2002;42:4216.

76. Evans O, Patterson K. Predictors of neck and shoulder pain in non-secretarial computer users. Int J IndErgon 2000;26:35765.

77. Jensen C, Ryholt CU, Burr H, Villadsen E, Christensen H. Work-related psychosocial, physical andindividual factors associated with musculoskeletal symptoms in computer users. Work Stress2002b;16(2):10720.

78. Wahlstrom J, Hagberg M, Johnson PW, Svensson J, Rempel D. Influence of time pressure and verbalprovocation on physiological and psychological reactions during work with a computer mouse. Eur J ApplPhysiol 2002;87:25763.

79. Smith MJ, Carayon P, Sanders KJ, Lim S, LeGrande D. Employee stress and health complaints in jobs withand without electronic performance monitoring. Appl Ergon 1992;23(1):1727.

80. Tadros E. Corporate clock watching can create a world of stress and overtime for harried workers. SydneyMorning Herald 2004 04/02.

81. Jensen C, Finsen L, Sogaard K, Christensen H. Musculoskeletal symptoms and duration of computer andmouse use. Int J Ind Ergon 2002;30(45):26575.

82. Carayon P, Smith MJ, Hairns MC. Work organization, job stress, and work-related musculoskeletal dis-

orders. Hum Factors 1999;41(4):64463.83. Johnson P, Hagberg M, Wigaeus HE, Rempel D. Measuring and characterizing force exposures during

computer mouse use. Scand J Work Environ Health 2000;26(5):398405.84. Wahlstrom J. Physical load in computer mouse work. Working technique, sex and stress aspects. Goteborg:

National Institute for Working Life; 2001.

85. Macaulay M. The speed of mouse-click as a measure of anxiety during human-computer interaction. BehavInf Technol 2004;23(6):42733.

86. Feuerstein M, Huang GD, Pransky G. Workstyle, work-related upper extremity disorders. In: Gatchel R,Turk DC, editors. Psychosocial factors in pain. New York: Guilford Press; 1999. p. 17592.

87. Ekberg K, Eklund J, Tuvesson M, Ortengren R, Odenrick P, Ericson M. Psychological stress and muscle

activity during data entry at visual display units. Work Stress 1995;9(4):47590.88. Waersted M, Westgaard RH. Attention-related muscle activity in different body regions during VDU work

with minimal activity. Ergonomics 1996;39(4):66176.89. Waersted M, Bjorklund RA. The effect of motivation on shoulder-muscle tension in attention demanding

tasks. Ergonomics 1994;37(2):36376.90. Silverstein B, Fine LJ, Armstrong TJ. Hand wrist cumulative trauma disorders in industry. Brit J Ind Med

1986;43:77984.91. Moore A, Wells R, Ranney D. Quantifying exposure in occupational manual tasks with cumulative trauma

disorder potential. Ergonomics 1991;34(12):143353.92. Feuerstein M, Armstrong T, Hickey P, Lincoln A. Computer keyboard force and upper extremity symp-

toms. J Occup Environ Med 1997b;39(12):114453.93. Arndt R. Work pace, stress, and cumulative trauma disorders. J Hand Surg 1987;12A(5):8669.

764 J Occup Rehabil (2007) 17:743765

13


23/24

94. Knardahl S. Psychophysiological mechanisms of pain in computer work: the blood vessel-nociceptorinteraction hypothesis. Work Stress 2002;16(2):17989.

95. Palmerud G, Sporrong H, Herberts O, Kadefors R. Consequences of trapezius relaxation on the distributionof shoulder muscle forces: an electromyographic study. J Electromyograph Kinesiol 1998;8:18593.

96. National Institute for Working Life. Good working technique and variety in breaks. In: Theme Compu-terwork; 2006.

97. Toomingas A, Theorell T, Michelsen H, Nordemar R. Associations between self-rated psychosocial work

conditions and musculoskeletal symptoms and signs. Scand J Work Environ Health 1997;23:1309.98. Winkel J, Oxenburgh M. Towards optimizing physical activity in VDT/office work. In: Sauter SL, Dainoff

MJ, Smith MJ, editors. Promoting health and productivity in the computerized office. London: Taylor &Francis; 1990. p. 94117.

99. Henning RA, Jacques P, Kissel GV, Sullivan AB, Alteras-Web SM. Frequent short rest breaks fromcomputer work: effects on productivity and well-being at two field sites. Ergonomics 1997;40(1):7891.

100. Galinsky TL, Swanson NG, Sauter SL, Hurrell JJ, Schleifer LM. A field study of supplementary rest breaksfor data-entry operators. Ergonomics 2000;43(5):62238.

101. Sundelin G, Hagberg M. The effects of different pause types on neck and shoulder EMG activity duringVDU work. Ergonomics 1989;32(5):52737.

102. McLean L, Tingley M, Scott RN, Rickards J. Computer terminal work and the benefit of microbreaks. ApplErgon 2001;32(3):22537.

103. Ferreira M, de Souza Conceicao GM, Saldiva PHN. Work organisation is significantly associated with

upper extremities musculoskeletal disorders among employees engaged in interactive computer-telephonetasks of an international bank subsidiary in San Paulo, Brazil. Am J Ind Med 1997;31:46873.

104. Thompson DA. Effect of exercise breaks on musculoskeletal strain among data-entry operators: a casestudy. In: Sauter S, Dainoff M, Smith M, editors. Promoting health and productivity in the computerizedoffice. London: Taylor & Francis.; 1990. p. 11827.

105. Fenety A, Walker JM. Short-term effects of workstation exercises on musculoskeletal discomfort andpostural changes in seated video display unit workers. Phys Ther 2002;82:57889.

106. Monsey M, Ioffe I, Beatini A, Lukey B, Sanitiago A, James AB. Increasing compliance with stretch breaksin computer users through reminder software. Work 2003;21:10711.

107. Kilbom A. Repetitive work of the upper extremity: Part II the scientific basis (knowledge base) for theguide. Int J Ind Ergon 1994;14:5986.

108. Jozsa L, Kannus P. Human tendons : anatomy, physiology, pathology. Champaign: Human Kinetics; 1997.109. Stevenson M, Ameratunga S, McClure R. The rationale for prevention. In: McClure R, Stevenson M,

McEnvoy S, editors. The scientific basis of injury prevention. Melbourne: IP Communications; 2004.110. Ramachandran A. New adventures in accounting. Sydney Morning Herald May 2627, 2007; Section 5.

J Occup Rehabil (2007) 17:743765 765

13


24/24

Reproducedwithpermissionof thecopyrightowner. Further reproductionprohibitedwithoutpermission.

Documents

The Impact of a Computerized Work Environment on Professional Occupational Groups and Behavioural and Physiological Risk Factors for Musculoskeletal Symptoms: A Literature Review