Article

The effect of using a laptopstation compared to using a standard laptop PC on the cervical spine torque, perceived strain and productivity

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Abstract

The objective of this study was to assess the effect of using a laptopstation and a laptop PC and how this difference in work set-up affected the mechanical load on the neck (C7-Th1 segment), the subjective evaluation of strain on the neck and productivity. Ten healthy male students at Umeå University, Sweden with an average of 10 years of PC work experience and an average of 18 months of laptop PC work experience participated in the study. For each research subject measurements were divided into two parts; sitting working at the ErgoQ laptopstation in test situation A, and sitting working at a conventional laptop PC, test situation B. Each part took 4h and was scheduled on two consecutive days. Photography and biomechanical analysis was used to calculate the torque at the neck. To examine perceived strain the Borg Scale was used and to assess performance a productivity score was calculated. The results in the study demonstrated a significant (p<0.05) difference with the use of the laptopstation resulting in decreased torque at the C7-Th1 segment, less perceived strain at the neck and a higher productivity score. In conclusion, the results of the study confirm the importance of adjustable work tools that recognize anthropometric differences and biomechanics to meet the needs of individual customers during continuous visual display terminal work.

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... The elevated keyboard height can subsequently cause the shoulder, neck, and whole body discomfort (Balliett et al., 1996;Bergqvist et al., 1995b;Erdelyil et al., 1988;Price & Dowell, 1998;Wu & Yang, 2005;Zhu & Shin, 2012). In order to prevent such awkward forearm and shoulder postures, along with raising the level of the laptop, an external keyboard is also recommended (Arshad et al., 2020;Berkhout et al., 2004). ...
... Several studies have been conducted to explore using laptop risers and external keyboard during laptop work. However, these studies have rarely addressed the load distribution on the neck, shoulder and back muscles objectively (Asundi et al., 2012;Berkhout et al., 2004;Sommerich et al., 2002). Asundi et al. (2012) compared postural changes while using a simple inclined stand under the laptop, as well as a commercially available riser with an external mouse and a keyboard. ...
... Having simultaneously evaluated muscle activities and postural changes, further insight would be provided into the biomechanical loads associated with the workstation setup (Asundi et al., 2012;Szeto & Lee, 2002). Berkhout et al. (2004) have demonstrated that the discomfort and the mechanical load is reduced on the neck by increasing the laptop height and using an external keyboard. Additionally, the user performance (the number of correct typed entries in a unit of time) has been improved (Berkhout et al., 2004). ...
Article
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Laptop work may increase risks of neck and back injuries in the long term due to awkward postures and increased mechanical loads on cervical and lumbar spine. This study was intended to compare the muscle activities and postural changes as well as discomfort of the neck and back resulted from the laptop work in a conventional and adjusted setup. 20 young healthy males performed two 8-min sessions of computer-mouse work and typing in a conventional setup and in an ergonomically adjusted setup during laptop work. In the adjusted setup, the screen height was individually adjusted by a riser and the keyboard was externally connected. The posture of the cervical, thoracic, lumbar spines, and shoulder, as well as electromyographic activity of cervical and lumbar erector spinae, multifidus, upper trapezius and anterior deltoid muscles, were recorded during the first and last 2 min of each computer work session. Having completed the computer work session, furthermore, the participants scored their neck, back, and general discomfort. The very research findings implied that adjusting the screen height and keyboard placement was effective during laptop work in reducing the cervical (−4.53 deg) and thoracic flexion angles (−3.14 deg) as well as the cervical erector spinae (−10.31%) and multifidus (−15.57%) muscle activities, and resulted in lower discomfort. The typing task was associated with higher muscle activity and awkward posture compared with the mouse work. As for workstation setup, simple modifications may reduce risk factors of musculoskeletal complaints. Eprint link: https://www.tandfonline.com/eprint/VWPYYWKXFTTM3MIYIZYW/full?target=10.1080/10447318.2020.1825204
... typing with the notebook PC on one's lap) introduce differences in the degrees of awkward postures and muscular loadings in the upper extremities [4,7]. One way to mitigate exposure of notebook PC users to awkward postures is using external equipment, such as notebook stations and external keyboards which serve to maintain more neutral postures [9,13]. In an experimental study [13], using a notebook station and an external keyboard culminated in a 24% decrease in neck flexion moment, 17% less subjective neck strain, and 17% higher productivity, compared to using notebook PC without a notebook station and an external keyboard. ...
... One way to mitigate exposure of notebook PC users to awkward postures is using external equipment, such as notebook stations and external keyboards which serve to maintain more neutral postures [9,13]. In an experimental study [13], using a notebook station and an external keyboard culminated in a 24% decrease in neck flexion moment, 17% less subjective neck strain, and 17% higher productivity, compared to using notebook PC without a notebook station and an external keyboard. There are different types of external notebook equipment available in the market such as notebook stands and docking stations, which can provide adjustability and serve to improve postural risks while using notebook PCs. ...
... Of the returned questionnaires, 18 of them were invalid due to missing data. Remaining 118 questionnaires were checked against four inclusion criteria: 1) to work on a notebook PC for > 4 hours/day [14,16,20,21], 2) to experience MSD in at least one upper extremity body region, 3) not to have experienced an MS injury, disorder, or operation within the past year before the study [6,13,15], and 4) not to have received medical treatment due to an MS problem within the past three months before the study [5,6,12]. In total, 73 (61.9%) of respondents were excluded due to these criteria, and the final participant group included 45 (38.1%) symptomatic occupational notebook PC users (Table 1). ...
Article
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This study explored the prevalence and work interference (WI) of upper extremity musculoskeletal discomfort (UEMSD) and investigated the associations of individual and work-related risk factors and using a notebook stand or docking station with UEMSD among symptomatic occupational notebook personal computer (PC) users. The participant group included 45 Turkish occupational notebook PC users. The study used self-reports of participants. The Turkish version of the Cornell Musculoskeletal Discomfort Questionnaire (T-CMDQ) was used to collect symptom data. UEMSD prevailed mostly in the neck, the upper back, and the lower back with prevalence rates of 77.8%, 73.3%, and 60.0% respectively, and with WI rates of 28.9%, 24.4%, and 26.7% respectively. Aggregated results showed that 44% of participants reported WI due to UEMSD in at least one body region. Significant risk factors were: being female, being aged <31 years, having computer work experience <10 years, and physical discomfort during computer use. UEMSD prevalence and WI rates were considerable in the neck, the upper back, and the lower back. Significant associations between certain risk factors and UEMSD were identified, but no association was found between using notebook stand and docking station and UEMSD among participants.
... A picture was used to clarify the monitor size item. Villanueva et al., 1998;Villanueva et al., 1996), and presence of external input devices (e.g., external keyboard, mouse, or numeric keypad) increased the use of neutral postures and discomfort relief (Berkhout, Hendriksson-Larsen, & Bongers, 2004;Sommerich et al., 2002). Rationale: The duration of computer use (Blatter & Bongers, 2002;Fredriksson et al., 2002;Jensen, Finsen, Sogaard, & Christensen, 2002;Tittiranonda et al., 1999) and frequency of rest breaks (Bergqvist, Wolgast, Nilsson, & Voss, 1995b;Tittiranonda et al., 1999) are considered potential risk factors for MSD/MSS. ...
... The color of the T-shirts was complementary to the marker's color. Angle formed by the vertical line and the line from the C7 spinous process to tragus (Ankrum & Nemeth, 2000) Shoulder angle a Angle formed by the line from the acromion process to the lateral epicondyle line relative to the trunk line (Villanueva et al., 1998) Elbow angle a Angle formed by the acromion process, lateral epicondyle of the humerus, and styloid process of the ulna (Villanueva et al., 1998) Thoracic bend angle Angle formed by the C7, inferior angle of the scapula, and superior iliac crest Trunk angle Angle formed by the horizontal line and the line between the C7 spinous process to superior iliac crest Villanueva et al., 1998) View angle Angle formed by the horizontal line and the line between the eye and the middle of the monitor (Berkhout et al., 2004;Jonai et al., 2002;Villanueva et al., 1998) Note. a includes the right and left angles ...
... The overhead camera was used to capture ulnar and radial deviation of the wrist. The height of the cameras was adjusted to the level of the C7 spinous process of each subject for the right and left cameras (lateral view) (Berkhout et al., 2004) and to the midpoint of a line joining the radial and ulna heads for the wrist and hand camera (overhead). ...
Article
Laptop computers are widely used by college students for academic and leisure activities (Cortes, Hollis, Amick, & Katz, 2002). However, there is limited research that identifies risk factors for musculoskeletal discomfort during laptop computer use in this population. This dissertation includes two studies: Study 1: This survey study explores characteristics of laptop computer use and relationships between laptop-related risk factors and discomfort; Study 2: This randomized cross-over study examines the effects of three most common laptop workstation setups on upper body postures, discomfort, and task productivity.Thirty students were recruited from the University of Pittsburgh. The survey was a self-administered questionnaire. Subjects¡¯ posture were videotaped while typing for 10 minutes in six laptop workstation setups (desktop sitting, chair sitting, lying prone, lying supine, floor sitting, and lap sitting), and the three most common workstation setups were analyzed. Body angles were digitized at 10-time points and averaged using ImageJ. Typing style was identified using the Keyboard-Personal Computer Style Instrument. Discomfort was determined using a 10-cm VAS. Task productivity was assessed by typing speed and accuracy. Data were analyzed by ANOVAs and Bonferroni post-hoc comparisons.Subjects were primarily female (83.3%), with a mean age of 26.0¡¾7.3, and white (63.3%). Survey results showed that the most common workstation setups were desktop sitting, followed by lying supine and chair sitting. There were no statistically significant relationships between laptop-related factors (duration and type of workstation setup) and discomfort. Most body angles were significantly different between the three workstation setups: neutral wrists and ulnar deviation, upright trunk, and greater shoulder flexion during desktop sitting; greater neck flexion, wrist extension, and ulnar deviation during chair sitting; less neck flexion and greater wrist flexion and trunk extension during lying supine. For typing style, subjects showed large differences in static postures among the workstation setups. Less discomfort and faster typing speed were observed during desktop sitting, followed by lying supine, and then chair sitting. Overall more neutral postures and less discomfort were observed during desktop sitting, followed by lying supine and chair sitting. These findings highlight the importance of laptop workstation setup choice for preventing potential musculoskeletal problems.
... Placing the notebook on a higher working surface, to optimize neck posture, is not a viable solution as it leads to increased discomfort in all body parts, including the neck (Price and Dowell, 1998). Elevating the whole notebook computer with a non-input device peripheral, such as a laptop station, does improve neck postures, reducing cervical spine torque and perceived strain (Berkhout et al., 2004). As a result of these findings, practitioners and researchers typically recommend using an external monitor or elevating the notebook to raise the display screen and adding external input peripherals, especially for extended notebook use. ...
... Values with the same letter were not significantly different. Values with different letters are ranked such that A > B > C. spine (Harms-Ringdahl, 1986; Schuldt et al., 1986; Berkhout et al., 2004) and increased neck extensor muscle activity (Sommerich et al., 2001; Seghers et al., 2003; Turville et al., 1998). Epidemiologic evidence, however, for forward head and neck postures as a risk factor for MDSs is limited. ...
Article
This study quantified postures of users working on a notebook computer situated in their lap and tested the effect of using a device designed to increase the height of the notebook when placed on the lap. A motion analysis system measured head, neck and upper extremity postures of 15 adults as they worked on a notebook computer placed on a desk (DESK), the lap (LAP) and a commercially available lapdesk (LAPDESK). Compared with the DESK, the LAP increased downwards head tilt 6 degrees and wrist extension 8 degrees . Shoulder flexion and ulnar deviation decreased 13 degrees and 9 degrees , respectively. Compared with the LAP, the LAPDESK decreased downwards head tilt 4 degrees , neck flexion 2 degrees , and wrist extension 9 degrees. Users reported less discomfort and difficulty in the DESK configuration. Use of the lapdesk improved postures compared with the lap; however, all configurations resulted in high values of wrist extension, wrist deviation and downwards head tilt. STATEMENT OF RELEVANCE: This study quantifies postures of users working with a notebook computer in typical portable configurations. A better understanding of the postures assumed during notebook computer use can improve usage guidelines to reduce the risk of musculoskeletal injuries.
... Many studies have investigated posture during the use of either a desktop or laptop computer [9][10][11][12][13][14][15][16]. Most of these studies investigated postural changes during the use of one electronic device with different workstation configurations, e.g., using or not using arm rest [16]; few studies examined postural differences during the use of different electronic devices [13] or the same electronic device at different workstations [9]. ...
... Many studies have investigated posture during the use of either a desktop or laptop computer [9][10][11][12][13][14][15][16]. Most of these studies investigated postural changes during the use of one electronic device with different workstation configurations, e.g., using or not using arm rest [16]; few studies examined postural differences during the use of different electronic devices [13] or the same electronic device at different workstations [9]. Increased neck flexion while using a laptop compared to a desktop computer has been previously reported [13,17]. ...
Article
Background: Alternative methods of accessing the internet and performing computing-related work tasks are becoming common, e.g., using tablets or standing workstations. Few studies examine postural differences while using these alternative methods. Objective: To assess neck and upper limb kinematics while using a tablet, laptop and desktop computer (sitting and standing). Methods: Differences in neck flexion/extension, lateral flexion, rotation; elbow flexion/extension; wrist flexion/extension, radial/ulnar deviation; and shoulder elevation in 30 participants were assessed in four conditions, three in sitting (tablet, laptop and desktop computer) and one in standing (desktop computer). Three-dimensional motion capture recorded posture variables during an editing task. Differences between variables were determined using one-way ANOVA with Bonferroni post-hoc tests. Results: Compared to the desktop (sitting), tablet and laptop use resulted in increased neck flexion (mean difference tablet 16.92°, 95% CI 12.79-21.04; laptop 10.92, 7.86-13.97, P < 0.001) and shoulder elevation (right; tablet 10.29, 5.27-15.11; laptop 7.36, 3.72-11.01, P < 0.001). There were no meaningful posture differences between the sitting and standing desktop. Conclusions: These findings suggest that using a tablet or laptop may increase neck flexion, potentially increasing posture strain. Regular users of tablets/laptops should consider adjustments in their posture, however, further research is required to determine whether posture adjustments prevent or reduce musculoskeletal symptoms.
... Placing the notebook on a higher working surface, to optimize neck posture, is not a viable solution as it leads to increased discomfort in all body parts, including the neck (Price and Dowell, 1998). Elevating the whole notebook computer with a non-input device peripheral, such as a laptop station, does improve neck postures, reducing cervical spine torque and perceived strain (Berkhout et al., 2004). As a result of these findings, practitioners and researchers typically recommend using an external monitor or elevating the notebook to raise the display screen and adding external input peripherals, especially for extended notebook use. ...
... Values with the same letter were note significantly different. Values with different letters are ranked such that A > B > C. spine (Harms-Ringdahl, 1986; Schuldt et al., 1986; Berkhout et al., 2004) and increased neck extensor muscle activity (Sommerich et al., 2001; Seghers et al., 2003; Turville et al., 1998 ). Epidemiologic evidence, however, for forward head and neck postures as a risk factor for MDSs is limited. ...
Article
This study evaluated the use of simple inclines as a portable peripheral for improving head and neck postures during notebook computer use on tables in portable environments such as hotel rooms, cafés, and airport lounges. A 3D motion analysis system measured head, neck and right upper extremity postures of 15 participants as they completed a 10 min computer task in six different configurations, all on a fixed height desk: no-incline, 12° incline, 25° incline, no-incline with external mouse, 25° incline with an external mouse, and a commercially available riser with external mouse and keyboard. After completion of the task, subjects rated the configuration for comfort and ease of use and indicated perceived discomfort in several body segments. Compared to the no-incline configuration, use of the 12° incline reduced forward head tilt and neck flexion while increasing wrist extension. The 25° incline further reduced head tilt and neck flexion while further increasing wrist extension. The 25° incline received the lowest comfort and ease of use ratings and the highest perceived discomfort score. For portable, temporary computing environments where internal input devices are used, users may find improved head and neck postures with acceptable wrist extension postures with the utilization of a 12° incline.
... Increased use of the laptop can thus elicit posturerelated complaints such as headache and neck pain. Sitting behaviour during laptop use is characterized by an augmented neck flexion and head-tilt (Straker et al., 1997;Berkhout et al., 2004), less head movement, a shorter viewing distance and a larger forward head position . A more pronounced forward head position is a typical feature in patients with migraine, cluster headache, cervicogenic headache, tension-type headache, neck pain and temporo-mandibular dysfunction (Fernández-de-Las-Peñas, 2010;Abboud et al., 2013). ...
... Sitting behaviour during laptop use is characterized by an augmented neck flexion and head-tilt (Straker et al., 1997;Berkhout et al., 2004), less head movement, a shorter viewing distance and a larger forward head position . A more pronounced forward head position is a typical feature in patients with migraine, cluster headache, cervicogenic headache, tension-type headache, neck pain and temporo-mandibular dysfunction (Fernández-de-Las-Peñas, 2010;Abboud et al., 2013). These postural features cause an increased load on the musculoskeletal system (McLean, 2005;Hamilton et al., 2005) and might explain the higher incidence of headache and neck pain in video display users (Lewis et al., 2001). ...
... As reported by Vink and Hallbeck [5], although people use some products daily, only few papers consider the concept of a localized comfort experience in relation to these products use. Every year many products are designed and launched but these are seldom redesigned in order to improve their comfort performances. ...
Article
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Computer aided technologies (CAT) are becoming an indispensable instrument to design, improve and manufacture new products and services. Digital human modelling (DHM) systems allow to simulate the Human-artifact interface and to evaluate, in early step of design process, the ergonomic performances of new products or workplaces. In particular, for products that have to be used in a “constrained” workplace, different tasks and activities are associated with different postures. The aim of this study is to investigate the influence of anthropometric characteristics and expectations on the postural comfort perception through the CAT/DHM systems, while using four office devices: desktop computer, laptop computer, tablet and smartphone. A statistical sample of healthy students was selected and their anthropometric characteristics were measured. The postures assumed by the participants were gathered in a not-invasive way by cameras. The angular detection was performed directly on snapshots by using Kinovea® software. Human joints’ an-gles were used for the virtual-postural analysis, through DELMIA® software. The evaluation of postural comfort was obtained in two ways: CaMAN® software developed by the researchers from the Department of Industrial Engineering in Salerno (Italy) was used to calculate the objective comfort indexes while an appropriate questionnaire, given to subjects during the devices usage, was used to evaluate the subjective com-fort indexes. The results of analyses show a difference between subjective and objective postural comfort indexes for all the devices: this difference has been associated to the expectations.
... The increasing use of computers is believed to have caused computer-related disorders (CRDs), such as eye fatigue, stiff shoulders, upper extremity pain, lower back pain, and mental stress [3,4]. Factors that can contribute to these conditions include the setting of the computer screen, which affects working posture [5], operating the computer for extended periods [6][7][8], and tasks that require repetitive and monotonous motions [9][10][11][12]. Additionally, mental stress levels are known to increase with the duration of computer-related tasks. ...
Article
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Objectives: This study investigated the association between task-induced stress and fatigue by examining the cardiovascular responses of subjects using different mouse positions while operating a computer under time constraints. Material and methods: The study was participated by 16 young, healthy men and examined the use of optical mouse devices affixed to laptop computers. Two mouse positions were investigated: (1) the distal position (DP), in which the subjects place their forearms on the desk accompanied by the abduction and flexion of their shoulder joints, and (2) the proximal position (PP), in which the subjects place only their wrists on the desk without using an armrest. The subjects continued each task for 16 min. We assessed differences in several characteristics according to mouse position, including expired gas values, autonomic nerve activities (based on cardiorespiratory responses), operating efficiencies (based on word counts), and fatigue levels (based on the visual analog scale - VAS). Results: Oxygen consumption (VO(2)), the ratio of inspiration time to respiration time (T(i)/T(total)), respiratory rate (RR), minute ventilation (VE), and the ratio of expiration to inspiration (Te/T(i)) were significantly lower when the participants were performing the task in the DP than those obtained in the PP. Tidal volume (VT), carbon dioxide output rates (VCO(2)/VE), and oxygen extraction fractions (VO(2)/VE) were significantly higher for the DP than they were for the PP. No significant difference in VAS was observed between the positions; however, as the task progressed, autonomic nerve activities were lower and operating efficiencies were significantly higher for the DP than they were for the PP. Conclusions: Our results suggest that the DP has fewer effects on cardiorespiratory functions, causes lower levels of sympathetic nerve activity and mental stress, and produces a higher total workload than the PP. This suggests that the DP is preferable to the PP when operating a computer.
... Os computadores portáteis podem ser usados em uma variedade de posturas quando não acoplado à estação de trabalho (GOLD et al., 2012), entretanto o aumento da sua portabilidade também aumenta a exposição à potenciais fatores de risco por queixas musculoesqueléticas em relação aos computadores de mesa (ASUNDI et al., 2012). Em particular, uma vez que o visor e teclado são ligados, a altura do ecrã é normalmente inferior à recomendada(STRAKER et al., 1997;BERKHOUT et al., 2004; ASUNDI et al., 2012).Usuários de computadores portáteis relataram maiores constrangimentos posturais e atividades musculares do pescoço do que os de computadores de mesa. As queixas de desconforto ocular e musculoesqueléticos, bem como dificuldade de digitação foram maiores durante o trabalho com os computadores portáteis(JONAI et al., 2002). ...
... Entretanto, Kim et al. (2014) afirma que características do teclado podem contribuir para desordens musculoesqueléticas dos membros superiores. Estudos mostram um aumento no ângulo de flexão do pescoço em usuários de notebook quando comparando ao uso de computadores de mesa, fator que pode aumentar o risco de dores e lesões (SZETO, 2002;BERKHOUT et al., 2004;SAIED et al., 2013). ...
Conference Paper
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Resumo Inadequações ergonômicas em notebooks podem causar danos gradativos à saúde do usuário. Procurando investigar quais adequações poderiam melhorar a ergonomia deste produto, realizou-se um levantamento dos equipamentos lançados nos últimos 5 anos pelos 5 maiores fabricantes, analisando teclado, touchpad e tela. Após análise de 35 modelos do produto, mapeou-se as inadequações ergonômicas encontradas. Produziu-se então indicações para a configuração ergonômica ideal a partir de discussões em um grupo focal, buscando as possíveis inovações incrementais para tornar notebooks mais ergonômicos. Palavra-chave: ergonomia de produto, notebooks, inovação 1. Introdução e objetivo O uso de notebook é comum nos postos de trabalho e lazer, substituindo, muitas vezes, os computadores de mesa devido à sua mobilidade. Entretanto, Kim et al. (2014) afirma que características do teclado podem contribuir para desordens musculoesqueléticas dos membros superiores. Estudos mostram um aumento no ângulo de flexão do pescoço em usuários de notebook quando comparando ao uso de computadores de mesa, fator que pode aumentar o risco de dores e lesões (SZETO, 2002; BERKHOUT et al., 2004; SAIED et al., 2013). Percebe-se que a indústria de computadores portáteis prioriza outros fatores no projeto do produto, tais como custos, peso, design e padronização do layout dos controles. Entretanto, segundo Guimarães (2006), quando um produto é realmente projetado para uma pessoa, deve considerar suas características, capacidades, habilidades, aptidões e limitações. Em busca desse repensar, a inovação pode encontrar novas formas de servir a mercados já estabelecidos e maduros, por meio do relacionar, detectar oportunidades e aproveitá-las. (TIDD e BRESSANT, 2015). Este estudo tem por objetivo investigar as características da tela, teclado e touchpad de notebooks, verificando as inadequações de design para o usuário sob a perspectiva ergonômica, e a partir desses resultados indicar designs alternativos como potencial de inovações para este segmento de negócios (ou produto). As próximas subseções definem as características ergonômicas avaliáveis dos notebooks e as características das inovações incrementais. Já a seção 3 trata dos passos metodológicos utilizados na seção 4. Essas discussões tratam das inadequações ergonômicas encontradas no grupo de produtos, incrementadas por propostas inovadoras oriundas de um grupo focal de especialistas em busca de inovações. 1.1 Projeto Ergonômico de Produto Ao aplicar ergonomia ao projeto de produtos, deve-se considerar fatores éticos, econômicos e legais. Entretanto, além dos benefícios ao trabalhador, o projeto ergonômico pode representar uma vantagem competitiva, reduzir o custo com acidentes e doenças do trabalho, e oferecer vantagem nas transações comerciais pela observância da norma (GUIMARÃES, 2006).
... The interview guide was sent to the interviewees in advance so that they Strain perception (health) Issues might arise from the perception of strain during certain operations. In this line, Berkhout et al. (2004) already investigated how different work setups affected the mechanical workload and the subjective evaluation of strain and productivity, confirming the importance of adjustable work tools that recognize the needs of the individual Acceptance (employee, internal) Issues might arise from the retention of employees in change processes. Previous studies with regard to lean implementation, for instance, found that a positive employee perception with regard to the change process is affected by commitment, the work method, beliefs, and communication (Losonci et al. 2011) Versatility (customer, external) Issues might arise from external flexibility requirements being imposed on the operational warehouse processes. ...
Article
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In many industrial countries, demographic changes towards an aging society go hand in hand with the need for ergonomic workplaces. Therefore, it is necessary to rethink workplace designs and work processes, particularly in industrial professions, such as logistics. As logistics activities are still characterized by a high amount of manual effort, they represent a suitable field for gaining empirical insights into the implementation of automation and ergonomic practices to inform social sustainable warehousing logistics strategies. By assuming a paradox perspective, this study accordingly examines the research question to which extent tensions arise in the context of sustainable warehousing regarding the implementation of technical automation and improved ergonomic processes. To answer this question, automation and ergonomics practices are studied at two logistics service providers and an industrial manufacturer in Germany. By applying a mixed-methods approach, the study analyzes empirical data derived from semi-structured interviews with logistics and human resource managers at four warehouse sites of these companies. Besides identifying relevant criteria and paradoxical tensions in improving handling processes in the specific cases, technology alternatives were evaluated from blue-collar employees' perspectives using an analytic hierarchy process (AHP) survey. The present study provides evidence that paradoxical tensions with regard to belonging and performing, as well as between organizational levels and through the change process itself are most important in this context. In this line, the current study contributes to theory and practice by providing insights into paradoxical tensions in warehousing logistics and discussing how automation and ergonomic transformational processes can be successfully managed through addressing interrelated demands of blue-collar workers, managers, and customers.
... It is possible to separate (or de-link) the input and visual display area to facilitate good physical and visual posture. For example, when working with a laptop, use a laptop-station together with an external keyboard and mouse [15] (see Fig. 3). However, making these modifications means that the user needs to purchase and carry additional accessories. ...
Article
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Mobile technology has revolutionised how we work. It is now relatively easy to work anywhere and anytime, but this has placed the onus is on mobile (or flexible) workers to set up their own work environment for comfort and ease of use. Vision is an important driver of posture, and hence visual ergonomics principles are integral for setting up digital devices. If mobile workers do not have visual ergonomics knowledge, or are unable to apply visual ergonomics knowledge to appropriately set up their work environment, then they are at risk of developing visual-related occupational health issues due to exposure to adverse physical work environments. To address this potential health care issue, we propose the introduction of Visual Ergonomics Health Literacy. This would provide mobile workers (including school children) with the knowledge and skills to set up their work environment for comfort and ease of use, wherever they work. It is important to address this issue now before we have a widespread epidemic of discomfort and injury from not applying sound visual ergonomics principles to work environments.
... 1,2 Multifactorial interactions among physical workload, psychosocial factors, duration of computer use, and sitting posture contribute to the development of such neuromusculoskeletal complaints. [3][4][5][6][7][8][9] Desk work typically elicits poor ergonomic postures, which are characterized by a lack of postural variability, less head movement, an increased neck flexion, and a chin poke. [9][10][11][12][13] Physical symptoms, such as headache, increase with the duration of daily visual display terminal use. ...
Article
Objective The purpose of this study was to compare the habitual cervical posture between a headache group and control group by using a (1) relative approach (ratio habitual cervical posture to maximal active cervical flexion) and a (2) longitudinal approach compared with a conventional approach. Methods Case-controlled longitudinal (pre-post) comparison of the habitual cervical posture referred to the maximal active cervical flexion between 17 women with secondary episodic cervicogenic headache (23.2 ± 1.8 years) and 17 matched controls (23.6 ± 2.2 years) before and after a desk task. Habitual cervical posture and maximal active cervical flexion were measured with a cervical range of motion device (degrees) before and after a desk task (manually completing the Headache Impact Test-6, 36-Item Short Form Health Survey, and general informative questionnaire during 20 minutes). Results During the pretest, the headache group differed significantly (P < .05) from the control group by showing a (1) smaller maximal active cervical flexion, and (2) positive correlation (ρ 0.56) between maximal active cervical flexion and the habitual cervical posture. After the desk task, the headache group vs the control group showed a significant (P < .05) (1) habitual cervical posture toward flexion, (2) negative correlation (ρ -0.64) between more cervical flexion at the pretest and a more cervical extension during the post-test, and (3) positive association (P < .001) between a larger habitual cervical posture referred to the maximal active cervical flexion and a higher headache intensity. Conclusion Longitudinal measurements of the ratio habitual cervical posture to the maximal active cervical flexion seem to be more sensitive to capture small cervical postural differences between patients with secondary cervicogenic headache and a control group compared with absolute, cross-sectional measurements.
... Berkhout et al. [5] studied the effect of load on the neck using a laptop compared to a laptop in a laptop docking station in 10 males with no report of preexisting musculoskeletal complaints and found that laptop docking stations resulted in an improvement in work productivity, decrease torque in C7-T1, and less strain on the neck. ...
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Laptop computers are used more often than desktop computers, especially among graduate students. Many common laptop habits can have severe physiological effects on the user ranging from eye strain, poor posture, upper extremity pain, and overuse injuries. Thus, it is important to educate students on the best ergonomic position to use laptops. This study investigates the efficacy of a laptop ergonomic education session and its effects on graduate students’ knowledge and behaviors regarding proper laptop use. A convenience sample of control and experimental groups was used and consisted of 83 occupational therapy (OT), 63 physical therapy (PT), and 26 nurse anesthesia (NA) graduate students. The sample size was 172, with 94 graduate students in the control group and 78 graduate students in the experimental. All study participants completed an initial ergonomics questionnaire. The experimental group was given an ergonomics education session following the questionnaire. Approximately 4 weeks after both groups completed the initial questionnaire; a follow up questionnaire was administered. Results showed that subjects demonstrated a statistically significant improvement in ergonomics knowledge after they completed the ergonomic educational session. Some participants reported making adaptations to laptop positioning and equipment use following the educational session. Thus, participating in ergonomic education can positively influence awareness of body mechanics relative to laptop workstation design.
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Computer use by children is common and there is concern over the potential impact of this exposure on child physical development. Recently principles for child-specific evidence-based guidelines for wise use of computers have been published and these included one concerning the facilitation of appropriate physical development. This paper reviews the evidence and presents detailed guidelines for this principle. The guidelines include encouraging a mix of sedentary and whole body movement tasks, encouraging reasonable postures during computing tasks through workstation, chair, desk, display and input device selection and adjustment and special issues regarding notebook computer use and carriage, computing skills and responding to discomfort. The evidence limitations highlight opportunities for future research. The guidelines themselves can inform parents and teachers, equipment designers and suppliers and form the basis of content for teaching children the wise use of computers. STATEMENT OF RELEVANCE: Many children use computers and computer-use habits formed in childhood may track into adulthood. Therefore child-computer interaction needs to be carefully managed. These guidelines inform those responsible for children to assist in the wise use of computers.
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Nowadays, using of laptops is increasing. Laptops are designed foremost to be portable but not ergonomics of use for long periods. Laptop design is not ergonomic; consequently users are not free to configure the equipment in working. A high intensity of using laptop can occur of fatigue. One of product that designed to reduce fatigue is laptop support. The purpose of this study was to examine the effect of using laptop support to human fatigue. The method was using a quantitative approach by experimental design. The Experimental design was single group, pretest-posttest design. The subjects were 40 students of the Faculty of Psychology, University of Sumatera Utara. The sampling technique was simple random sampling. Data was collected using Subjective Self Rating Test, Nordic body map questionnaire and statistically analyzed using paired sample t-test. The results showed that there was a significant difference in fatigue between before and after using of laptop support. It showed that using of laptop support has effect to reduce fatigue on laptop user. The implication of this study is that it does contribute to understanding of the ways by which laptop user to reduce fatigue by using an ergonomic laptop support.
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Os atributos necessários para o desenvolvimento de produtos podem ser avaliados e verificados por meio da usabilidade. No caso dos músicos de violino e viola, acessórios como a espaleira são necessários para melhorar o posicionamento, minimizar a tensão muscular na região do pescoço e liberar a mão esquerda para a digitação das notas. Mesmo assim, problemas como queixas musculoesqueléticas são indicados na literatura. Este estudo avaliou as espaleiras utilizadas por 10 músicos de uma orquestra, por meio dos princípios de usabilidade, e investigar a percepção dos músicos relacionada à satisfação, eficácia e eficiência das espaleiras, por meio de questionários com perguntas abertas. As problemáticas estão relacionadas à usabilidade, sendo as espaleiras consideradas eficazes para as práticas instrumentais, precisando ser mais eficientes, fazendo com que a correta postura seja mantida e que menores ocorrências musculoesqueléticas sejam geradas em função dos ajustes inadequados dos acessórios.
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The purposes of this study were to characterize the influence of seat back angle variations on the neck comfort of sleeping passengers without a pillow and provide suggestions for the design of economy-class seats. In this study, 17 subjects were subjected to a sleep experiment to test the effect of the backrest angle on head and neck rotation and the fatigue level of the neck muscles. The results showed that a reclined backrest (positioned at 110°) caused greater rotation of the head and neck and greater fatigue of the neck muscles than a vertical backrest. Additionally, the higher was the subject's head extended above the top of the backrest, the more complicated the head and neck rotation was and the more intense the stretching of muscles was. We conclude that, when sleeping in a sitting position without head support, passengers were more likely to experience neck muscle fatigue with the reclined backrest than with the vertical backrest. Passenger height was also found to be an important factor contributing to head and neck fatigue. On the basis of the experimental results, we offer suggestions for the design of backrests to improve passengers' sleeping experience. Our research and suggestions provide a new path for innovation in the design of economy-class seats and could help to improve the travel experience.
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This paper summarises the results of studies related to working with visual display units (VDUs) and the associated risk factors for the upper limb. First, the analysis pattern and methodology are defined. Then, the data linked to work organization, stress and psychosocial factors are reviewed, along with data related to biomechanical demands and spatial organisation of the workplace (screen consultation, keyboard entry and mouse manipulation). This bibliographic review demonstrates that, when working with VDUs, the demands on the upper limb are numerous and varied. Stress and psychosocial factors can have a great impact on the entire upper limb, particularly at its root in the shoulder and neck area. Among the biomechanical demands, static posture also exerts a strong pressure on the root of the upper limb. Certain joint positions are also particularly demanding on this limb, particularly at the wrist and shoulder. Whatever the joint, the risk of musculoskeletal disorders (MSDs) of the upper limb is greater as the frequency and duration of these demands increases, even if they are often of low intensity. ne concept of duration of exposure would, therefore, appear to be primordial. In addition, the demands are greater with the use of the mouse rather than the keyboard as they combine cognitive load, static posture and sometimes biomechanical exertion. Finally, this review highlights the conflict that exists between wrist and shoulder in the case of keyboard use : a reduction in demands placed on one of these joints increases demands on another. In terms of prevention, it is therefore vital to take the entire upper limb into consideration. More generally, the use of information appearing in this paper in order to support the prevention of musculoskeletal disorders with VDUs must adopt a global approach, taking into account all the factors identified.
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Background: With the increase of tablet usage in both office and industrial workplaces, it is critical to investigate the influence of tablet usage on spine posture and movement. Objective: To quantify spine kinematics while participants interacted with a tablet or desktop computer. Methods: Fourteen participants volunteered for this study. Marker clusters were fixed onto body regions to analyze cervical and lumbar spine posture and sampled at 32 Hz (Optotrak Certus, NDI, Waterloo, Canada). Participants sat for one hour in total. Cervical and lumbar median angles and range of motion (10th to 90th % ile angles) were extracted from amplitude probability distribution functions performed on the angle data. Results: Using a sloped desk surface at 15°, compared to a flat desk, influenced cervical flexion (p = 0.0228). Completing the form fill task resulted in the highest degree of cervical flexion (p = 0.0008) compared to the other tasks completed with cervical angles between 6.1°-8.5° higher than emailing and reading respectively. An interaction between device and task (p = 0.0061) was found for relative lumbar median spine angles. Conclusions: Increased lumbar flexion was recorded when using a computer versus a tablet to complete various tasks. Task influenced both cervical and lumbar spine posture with the highest cervical flexion occurring while completing a simulated data entry task. A work surface slope of 15° decreased cervical spine flexion compared to a horizontal work surface slope.
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Background: User satisfaction from a device is an especially term in the design world that covers broad concept of the design content. Objective: The aim of the present study was to design satisfaction questionnaire and survey of satisfaction of student's from the laptop desks. Methods: This analytical - descriptive study has conducted for survey student's satisfaction from the laptop desks in the male dormitories of Qazvin University of Medical Sciences in 2017. Fifty students (17 boys and 33 girls) were recruited by simple stratified random sampling. Based on scientific literature and point of view faculty member and student, 43 items of questionnaire were drafted and reliability and validity were evaluated and only 23 question confirmed. Data analyzed using Pearson correlation and Cronbach's alpha. The percentage of students' satisfaction was determined using cut-off point of questionnaire in receiver operating characteristic (ROC) curve. Findings: The results of Cronbach's alpha and correlation of questionnaire obtained 0.95 and 0.83 respectively. According to the ROC curve, cut-point of satisfaction questionnaire of the students from laptop desks obtained 64.5. Then, the percent of student satisfaction (boys and girls) from desk 1 and 2 were 47.1%, 66.7% and 11.8%, 42.4% respectively. Conclusion: One-third of students from desks were dissatisfied. So, the use of opinion ergonomics specialists and particularly users when designing is necessary for increase user's satisfaction from design of laptop desks.
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O Ministério Público do Trabalho da 15ª Região (MPT) em 2002, recebeu denúncias relatando informalidade, trabalho escravo e mortes por exaustão no setor sucroalcooleiro. Esse órgão organizou um programa de ações conjuntas com o Ministério do Trabalho, o Centro de Referência em Saúde do Trabalhador de Piracicaba, o Sindicato dos Trabalhadores Rurais e a Pastoral Rural para interceder naquele setor. Este estudo procurou conhecer e explorar como os atores participantes daquele programa do MPT avaliaram as ações empreendidas no período de 2004 a 2013. A pesquisa se baseou na análise documental dessas ações e em entrevistas semiestruturadas com os diferentes atores: procuradores do MPT, auditores do MT (Ministério do Trabalho), coordenador do CEREST (Centro de Referência em Saúde do Trabalhador), e representantes do Sindicato dos Trabalhadores e da Pastoral Rural. Essas intervenções resultaram em aproximadamente 100 diligências de fiscalização, autuação de 200 usinas e 850 empresas, e 600 TACs (Termo de Ajustamento de conduta). O programa beneficiou, direta ou indiretamente, 220 mil trabalhadores do setor. As maiores dificuldades encontradas foram: setor pulverizado territorialmente; equipes de fiscalização insuficientes; dificuldade técnica para aplicação das normas. Os avanços conquistados: adequação do ambiente laboral; fim das mortes por exaustão, menor precarização do trabalho. Na percepção dos entrevistados foi possível constatar a efetividade das intervenções no setor. PALAVRAS-CHAVE: Ministério Público do Trabalho; Mortes por Exaustão; Segurança do Trabalho; Precarização do Trabalho; Saúde do Trabalhador
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The aim of this study was to evaluate working conditions using a personal computer with a flat panel display (FPD) in terms of visual and musculoskeletal comfort. Measurements of viewing distance, viewing angle, head angle, neck angle and electromyogram (EMG) activities of the neck, shoulder and back muscles of visual display terminal (VDT) operators were compared at workstations using an FPD and a desktop personal computer (DPC). A notebook personal computer (NPC) with a 10.4 inches FPD, was used in this experiment. Each of 10 healthy subjects performed word processing tasks using both NPC and DPC workstations. Significant differences in the work posture while using the NPC and DPC were seen with viewing distance, viewing angle and head angle. The characteristic features of the work posture using the NPC were a remarkably short viewing distance and a forward inclination of the head. The value of integrated EMG (IEMG) of the neck muscle was greater while using the NPC than when using the DPC. These phenomena were caused by the structure of NPCs; most NPCs have a display and keyboard which cannot be separated and are not adjustable without tilt and swivel mechanisms. VDT devices that cannot be adjusted may potentially make operators assume a poor posture while working, which could cause visual and musculoskeletal disorders. To prevent visual and musculoskeletal problems using NPCs, a more upright head and neck position was recommended. The addition of a mechanism for adjustment of the height of an NPC display would allow a comfortable downward gaze without the loss of correct posture.
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The prevalence of neck pain in the general population ranges from 10 to 15%. The complaints can result in substantial medical consumption, absenteeism from work and disability. In this study we investigated the costs of neck pain in the Netherlands in 1996 to assess the financial burden to society. The study was based on prevalence data. Data sources included national registries, reports of research institutes and health care authorities. Direct health care costs were estimated for hospital care, general practice care and paramedical care. These costs were calculated using fees. Calculation of indirect costs (absenteeism and disability) was based on the Human Capital Method (HCM). As an alternative approach the Friction Cost Method (FCM) was used. The total cost of neck pain in The Netherlands in 1996 was estimated to be US $686 million. The share of these costs was about 1% of total health care expenditures and 0.1 % of the Gross Domestic Product (GDP) in 1996. Direct costs were $160 million (23%). Paramedical care accounted for largest proportion of direct costs (84%). When applying the HCM for calculating indirect costs, these costs amounted to $527 million (77%). The total number of sick days related to neck pain were estimated to be 1.4 million with a total cost of $185.4 million in 1996. Disability for neck pain accounted for the largest proportion (50%) of the total costs related to neck pain in 1996 ($341). When applying the FCM for calculating the indirect costs, these costs were reduced to $96 million. The costs related to neck pain in 1996 in The Netherlands were substantial. Some caution should be taken in interpretation, as a number of assumptions had to be made in order to estimate the total costs. The cost structure shown in this study, with high indirect costs, has also been found in other studies. From an economical point of view it seems to be important to prevent patients from having to take sick leave and disability. One way in achieving this goal is to develop and investigate more effective treatments for acute neck pain, in order to prevent patients developing chronic pain and disability. Another option is to protect chronic patients from sick leave and disability by careful management. Thus, also in the area of direct medical costs, there may be room for cost savings by stimulating and improving cost-efficiency and cost-effectiveness of the (para)medical care. In order to deal with the lack of specific disease information, more detailed information of medical consumption, sick leave and disability is required for future cost analysis.
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To evaluate and compare the postures and movements of the cervical and upper thoracic spine, the typing performance, and workstation ergonomic factors when using a desktop, notebook, and subnotebook computers. Repeated-measures design. A motion analysis laboratory with an electromagnetic tracking device. A convenience sample of 21 university students between ages 20 and 24 years with no history of neck or shoulder discomfort. Each subject performed a standardized typing task by using each of the 3 computers. Measurements during the typing task were taken at set intervals. Cervical and thoracic spines adopted a more flexed posture in using the smaller-sized computers. There were significantly greater neck movements in using desktop computers when compared with the notebook and subnotebook computers. The viewing distances adopted by the subjects decreased as the computer size decreased. Typing performance and subjective rating of difficulty in using the keyboards were also significantly different among the 3 types of computers. Computer users need to consider the posture of the spine and potential risk of developing musculoskeletal discomfort in choosing computers.
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Technology is continuing to advance so that computers are becoming an integral part of nearly every workplace. Recently, there has been an emergence of portable computers, as represented by notebook computers. Previous research has focused on the ergonomics of visual display terminals; however, minimal research has been conducted on the ergonomic implications of notebook computers in the workplace. This study investigated five subjects working in different environments. Still photography was used to assess the postural demands and joint angles adopted by the subjects using notebook computers. Subjective user discomfort and quantity of use was also recorded. The findings of this study suggest that increased forward head inclination was required by users to adequately operate the notebook computer due to lack of adjustability. Reported musculoskeletal discomfort was more frequent and more intense in the neck and upper back region.
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In the 1980's, the visual display terminal (VDT) was introduced in workplaces of many countries. Soon thereafter, an upsurge in reported cases of related health problems, such as musculoskeletal disorders and eyestrain, was seen. Recently, the flat panel display or notebook personal computer (PC) became the most remarkable feature in modern workplaces with VDTs and even in homes, A proactive approach must be taken to avert foreseeable ergonomic and occupational health problems from the use of this new technology, Because of its distinct physical and optical characteristics, the ergonomic requirements for notebook PCs in terms of machine layout, workstation design, lighting conditions, among others, should be different from the CRT-based computers, The Japan Ergonomics Society (JES) technical committee came up with a set of guidelines for notebook PC use following exploratory discussions that dwelt on its ergonomic aspects, To keep in stride with this development, the Technical Committee on Human-Computer Interaction under the auspices of the International Ergonomics Association worked towards the international issuance of the guidelines. This paper unveils the result of this collaborative effort.
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VDT tasks are rapidly increasing as the office automation prevails. Despite its numerous benefits, occupational hazards such as visual fatigue, eye strain, radiation and musculoskeletal stresses have emerged as an important issue. This study was designed to investigate the effects of work postures and anthropometric differences upon the musculoskeletal stresses experience by operators involved in conversational VDT tasks. Evaluation of the level of muscoloskeletal discomfort was performed for 297 VDT operators from three divisions of telecommunication company in Korea. The ergonomic variables of the VDT tasks and the operators' anthropometric variables were evaluated for 70 out of the 297 VDT operators. Factor analysis is used for identifying underlying pattern of discomfort and multiple regression analysis were performed to examine the relationship between the measured ergonomic variables and the musculoskeletal discomfort. This study indicates that the ergonomic variables have influences on the musculoskeletal discomfort. It is important to provide the workers with fully adjustable workstations so that they can maintain their work postures most suitable for the sustained VDT work. Furthermore, in order to achieve the best working conditions, VDT operators should be given a proper training for the adjustment of their workstations.
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More con strained posture and higher neck muscle activities have been reported among users of notebook computers than those of desktop computers. Complaints of eye and musculoskeletal d iscomfort as well as di fficulty of keying were greater during work with notebook computers. These reports ascribed the findings to the differences in the size of desktops and notebooks. Another ergonomic aspect of the notebook computer distinct from the CRT is its angle-dependent luminance contrast. The present study investigated the effects of liquid crystal display (LCD) tilt angle of a notebook computer on posture, muscle activities and somatic complaints in 10 subjects. At the tilt angle of 100°, the subjects were noted to have relatively less neck flexion. The static neck extensor muscle activity was also lowest at this tilt angle. Nonetheless, the complaint survey revealed higher rates of discomfort while viewing and using the LCD set at the tilt angle of 100°. The findings of this study strongly suggested that the ergonomic features and problems attributable to notebook computers are distinct from the desktop computers. The points of interest raised in this paper should be considered when contemplating the use of notebook computers.Relevance to industryThe use of notebook computers has increased steadily over the last 5 years , especially in Japan. Few authors have ventured to study the problems associated with these smaller computers . The results and suggestions of this stu dy may contribute to improve the design of notebook computers and the workstations .
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The survey investigated the use of laptop computers by children aged 10 to 17 yr at schools in Western Australia. Data collected included general participant information (e.g. age, height); locations and postures adopted for laptop use; time on task and consequences of both using and carrying laptops. 251 participants used the internet to complete the survey and 63 completed written surveys. Twenty participants were interviewed and observed using their laptops in various locations. The mean times for minimum and maximum periods of laptop use at one sitting ranged from 11.5–101.9 min. Mean daily use (3.2 h) and weekly use (16.9 h) was also shown to be high. Postures used by laptop users varied according to location, e.g. home, school and boarding house. Reported consequences of laptop use included technical faults, service and location limitations, hardware and software limitations, user limitations and physical consequences to the user. Sixty percent of students reported discomfort with laptop use and 61% of participants reported discomfort with carrying their laptop. Associations between school attended or year level with time on task and discomfort reports were evident.Relevance to industryThe use of laptop computers is increasing, both in educational settings and other industries. There is however minimal research on the physical consequences of laptop use by adults or children, and therefore recommendations for using laptop computers are tentative.
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Work in the manufacturing industry is associated with a high prevalence of cervicobrachial disorders.
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The effects of the VDT screen height on working posture and electromyographic (EMG) activities of the neck and shoulder muscles were determined in 10 healthy subjects. The subjects performed a mouse-driven interactive task at the screen height settings of 80, 100 and 120 cm. Changes in body positions were measured by video image and frame analysis. Surface EMG recordings were done on the neck extensor muscle and the descending part of the trapezius muscle, both on the right side. The results of the postural analysis showed that at higher screen height settings, the neck became significantly more erect. The subjects also assumed a more backward-leaning trunk position at higher screen heights. The EMG activities of the neck and shoulder muscles were related to the neck angle and trunk inclination, respectively. A more flexed neck produced significantly higher neck extensor muscle activities. A backward-leaning trunk was also noted to decrease trapezius muscle activity in some subjects.
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This study evaluated the postural implications of using a laptop computer. Laptop computer screens and keyboards are joined, and are therefore unable to be adjusted separately in terms of screen height and distance, and keyboard height and distance. The posture required for their use is likely to be constrained, as little adjustment can be made for the anthropometric differences of users. In addition to the postural constraints, the study looked at discomfort levels and performance when using laptops as compared with desktops. Statistical analysis showed significantly greater neck flexion and head tilt with laptop use. The other body angles measured (trunk, shoulder, elbow, wrist, and scapula and neck protraction/retraction) showed no statistical differences. The average discomfort experienced after using the laptop for 20 min, although appearing greater than the discomfort experienced after using the desktop, was not significantly greater. When using the laptop, subjects tended to perform better than when using the desktop, though not significantly so. Possible reasons for the results are discussed and implications of the findings outlined.
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A study was conducted on eight subjects, in order to investigate the influence of head posture with regards to the screen and copy holder position, the activity of cervical muscles and the subjective judgement given by the subjects. A total of eleven different positions (exercises) of screen and copy holder were investigated. Four different screen positions were examined in the upright (middle) sitting posture and three different screen positions were investigated in the backward sitting posture. In addition, four different positions of the copy holder were examined in the upright sitting posture. Head posture and muscle activity were continuously measured in each exercise for a duration of 5 min. At the end of each exercise, the subjects were asked how they judged the position of the screen and/or the copy holder in comparison with other positions. The results show that preference is to be given to a screen position in which the vision axis is horizontal or inclined slightly downwards. The copy holder should be arranged at one side of the screen.
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In the 1980's, the visual display terminal (VDT) was introduced in workplaces of many countries. Soon thereafter, an upsurge in reported cases of related health problems, such as musculoskeletal disorders and eyestrain, was seen. Recently, the flat panel display or notebook personal computer (PC) became the most remarkable feature in modern workplaces with VDTs and even in homes. A proactive approach must be taken to avert foreseeable ergonomic and occupational health problems from the use of this new technology. Because of its distinct physical and optical characteristics, the ergonomic requirements for notebook PCs in terms of machine layout, workstation design, lighting conditions, among others, should be different from the CRT-based computers. The Japan Ergonomics Society (JES) technical committee came up with a set of guidelines for notebook PC use following exploratory discussions that dwelt on its ergonomic aspects. To keep in stride with this development, the Technical Committee on Human-Computer Interaction under the auspices of the International Ergonomics Association worked towards the international issuance of the guidelines. This paper unveils the result of this collaborative effort.
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Appropriate visual display terminal (VDT) location is a subject of ongoing debate. Generally, visual strain is associated with higher placement, and musculoskeletal strain is associated with lower placement. Seeking resolution of the debate, this paper provides a comparison of results from previous lab-based monitor placement studies to recommendations and outcomes from viewing preference and neutral posture studies. The paper then presents results from a field study that addressed two outstanding issues: Does monitor placement in a workplace elicit postures and discomfort responses similar to those seen in laboratory settings? Results showed placements in the workplace elicited postures similar to those in lab studies. Additionally, preferred VDT location generally corresponded to the location in which less neck discomfort was reported, though that trend requires further investigation. Overall, there seems to be consistent evidence to support mid-level or somewhat higher placement, as a rule-of-thumb, considering preferred gaze angle and musculoskeletal concerns. However, optimal placement may be lower for some individuals or tasks.
Article
The aim of this study was to determine trapezius muscle hardness in 9 healthy volunteers before and after word processing tasks with a video display terminal (VDT) at three different heights. When using a desktop personal computer (PC), no change was observed in muscle hardness even after a 30-min task if a subject was in the reference posture with a declination angle formed by the Reid's line directed toward the upper edge of the PC screen and the horizontal plane within 5-10 degrees. However, an increase in muscle hardness was observed after a 15-min task in a posture of looking up at the screen (angle of elevation: 15-20 degrees) and after a 30-min task in a posture of looking down at the screen (angle of declination: 15-20 degrees). When the same tasks were performed with a notebook PC, muscle hardness increased after 15 min. Fifteen minutes of relaxation exercise reduced the muscle hardness caused by VDT work.
Neck and Back Pain: The Scientific Evidence of Causes, Diagnosis and Treatment. Lippincott Willliams & Wilkins A field evaluation of monitor placement effects in the VDT users
  • A L Nachemson
  • E Jonsson
  • Philadelphia
  • J P Psihogios
  • C M Sommerich
Nachemson, A.L., Jonsson, E., 2000. Neck and Back Pain: The Scientific Evidence of Causes, Diagnosis and Treatment. Lippincott Willliams & Wilkins, Philadelphia. Psihogios, J.P., Sommerich, C.M., et al., 2001. A field evaluation of monitor placement effects in the VDT users. Appl. Ergonomics 32, 313–325.
The ergonomics of notebook computers
  • Harbison