2,041 research outputs found

    Eur J Appl Physiol

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    PurposeThe aim of the present study was to determine whether there were any physiological changes in the muscle as a result of intensive computer use.MethodsUsing a repeated measures experimental design, eighteen subjects participated in four different eight-hour conditions: a control (no exposure) condition and three exposure conditions comprised of 6 hours of computer use (keyboard, mouse, and combined keyboard and mouse use) followed by 2 hours of recovery. In each condition, using 2 Hz neuromuscular electrical stimulation, eight temporal measurements were collected to evaluate the fatigue state (twitch force, contraction time, and \ubd relaxation time) of the right middle finger Flexor Digitorum Superficialis (FDS) muscle before, during, and after computer use.ResultsThe results indicated that 6 hours of keyboard, mouse, and combined mouse and keyboard use all caused temporal fatigue-related changes in physiological state of the FDS muscle. Keyboard use resulted in muscle potentiation, which was characterized by approximately 30% increase in twitch force (p < 0.0001) and 3% decrease (p = 0.04) in twitch durations. Mouse use resulted in a combined state of potentiation and fatigue, which was characterized by an increase in twitch forces (p = 0.002) but a prolonging (11%) rather than a shortening of twitch durations (p < 0.0001).ConclusionsWhen comparing mouse and keyboard use, the more substantial change in the physiological state of the muscle with mouse use (potentiation and fatigue compared to just potentiation with keyboard use) provides some physiological evidence which may explain why mouse use has a greater association with computer-related injuries.R21 OH009088/OH/NIOSH CDC HHSUnited States/R21 OH009088-0/OH/NIOSH CDC HHSUnited States

    Ergonomics of using a mouse or other non-keyboard input device

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    Ten years ago, when the Health and Safety (Display Screen Equipment) Regulations (HSE, 1992) were drafted, the majority of computer interaction occurred with text driven interfaces, using a keyboard. It is not surprising then that the guidance accompanying the DSE Regulations included virtually no mention of the computer mouse or other non-keyboard input devices (NKID). In the intervening period, graphical user interfaces, incorporating ‘windows, icons and pull down menus’ (WIMPS), with a heavy reliance on pointing devices such as the mouse, have transformed user computer interaction. Accompanying this, however, have been increasing anecdotal reports of musculoskeletal health problems affecting NKID users. While the performance aspects of NKID (e.g. accuracy and speed) have been the subject of detailed research, the possible implications for user health have received comparatively little attention. The research presented in this report was commissioned by the Health and Safety Executive to improve understanding of the nature and extent of NKID health problems. This investigation, together with another project examining mobile computing (Heasman et. al., 2000), was intended to contribute to a planned review and updating of the DSE Regulations and accompanying guidance

    Musculoskeletal disorders in demanding computer work - with air traffic control as a model

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    In computer work, musculoskeletal disorders are frequently reported, but the knowledge about causal relationships is limited. In air traffic control, female and male operators perform exactly the same computer work. Introduction of a new computer system implied a momentary change from a “varied” system containing different in-put devices, to a system characterized by intensive mouse-work. The effect of the change on the physical exposure was studied, as well as the musculoskeletal health before and after the change. In addition, gender differences and psychosocial factors were assessed. The physical workload, recorded in 14 subjects in both systems by technical measurements of postures, movements and muscular load, showed large differences: The mouse-intensive system was associated with lower movement velocities, less varying postures and less rest in the right forearm extensor muscles. The differences were amplified at high work intensity. Neck postures in females with neck/shoulders/upper back disorders were compared to those in healthy referents, but without significant differences. Musculoskeletal disorders in neck and upper limbs were assessed by standardised physical examinations in 148 air traffic controllers (71 women and 77 men) and the psychosocial work environment by questionnaire. Disorders in elbows/hands increased significantly after 20 months of work in the mouse-intensive system, while in neck/shoulders/upper back, there was no consistent change. There was no gender difference in elbows/hands disorders, while the females were at higher risk in neck/shoulders/upper back. Disorders in elbows/hands were not explained by psychosocial factors. Most likely, these findings are applicable to similar technological developments in other settings

    Ergonomic evaluation of office workplaces with Rapid Office Strain Assessment (ROSA)

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    The regular use of the computer in the office contributed to the appearance of many risk factors related with work-related musculoskeletal disorders (WRMSD) such as maintaining static sitting postures for long time and awkward postures of the head, neck and upper limbs, leading to increased muscle activity in the cervical spine and shoulders. The objective of this study was to evaluate the presence of risk factors for WRMSD in an office using the Rapid Assessment Office Strain method (ROSA). Based on the results of this ergonomic evaluation, an occupational gym program was designed and implemented. Thirty-eight workplaces were evaluated using the observation of the tasks and pictures records in order to characterize those tasks in more detail. The ROSA tool was applied by an observer, who selected the appropriate score based on the worker's posture as well as the time spent in each posture. Scores were recorded for the sections of the method, specifically Chair, Monitor and Mouse and Keyboard and Telephone. The scores were recorded in a sheet developed for the method. The mean ROSA final score was 3.61 ± 0.64, for Chair section was 3.45 ± 0.55, to Monitor and Telephone section was 3.11 ± 0.61, and to Mouse and Keyboard section was 2.11 ± 0.31. The results led to understand that the analyzed tasks represent situations of risk of discomfort and, according to the methods guidelines, further research and modifications of the workplace may be necessary. It should be emphasized that these scores may not be related to the poor available equipment but with the need to optimize their use by the workers. It was noticed also that the interaction of workers with the tasks and the adopted sitting posture at the computer throughout the day have effects at a muscular level, essentially for the cervical area and shoulders. ROSA tool is an useful and easy method to assess several risk factors associated with WRMSD, also allowing the design of specific occupational gym programs

    Computer work and musculoskeletal disorders of the neck and upper extremity: A systematic review

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    <p>Abstract</p> <p>Background</p> <p>This review examines the evidence for an association between computer work and neck and upper extremity disorders (except carpal tunnel syndrome).</p> <p>Methods</p> <p>A systematic critical review of studies of computer work and musculoskeletal disorders verified by a physical examination was performed.</p> <p>Results</p> <p>A total of 22 studies (26 articles) fulfilled the inclusion criteria. Results show limited evidence for a causal relationship between computer work per se, computer mouse and keyboard time related to a diagnosis of wrist tendonitis, and for an association between computer mouse time and forearm disorders. Limited evidence was also found for a causal relationship between computer work per se and computer mouse time related to tension neck syndrome, but the evidence for keyboard time was insufficient. Insufficient evidence was found for an association between other musculoskeletal diagnoses of the neck and upper extremities, including shoulder tendonitis and epicondylitis, and any aspect of computer work.</p> <p>Conclusions</p> <p>There is limited epidemiological evidence for an association between aspects of computer work and some of the clinical diagnoses studied. None of the evidence was considered as moderate or strong and there is a need for more and better documentation.</p

    Musculoskeletal symptoms of the upper extremities and the neck: A cross-sectional study on prevalence and symptom-predicting factors at visual display terminal (VDT) workstations

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    <p>Abstract</p> <p>Background</p> <p>The aim of this study was to determine the prevalence and the predictors of musculoskeletal symptoms in the upper extremities and neck at visual display terminal (VDT) workstations.</p> <p>Methods</p> <p>In a cross-sectional study 1,065 employees working at VDT > 1 h/d completed a standardised questionnaire. Workstation conditions were documented in a standardised checklist, and a subgroup of 82 employees underwent a physical examination.</p> <p>Results</p> <p>Using the Nordic Questionnaire, the 12-month prevalence of symptoms of the neck, shoulder region, hand/wrist, or elbow/lower arm was 55%, 38%, 21%, and 15% respectively. The duration of VDT work had a significant impact on the frequency of neck symptoms in employees performing such work > 6 h/d.</p> <p>Conclusion</p> <p>With regard to musculoskeletal symptoms of the upper extremities, preventive measures at VDT workstations should be focused on neck and shoulder symptoms (e.g. ergonomic measures, breaks to avoid sitting over long periods).</p

    Evaluation of Posture, Muscle Activity and Comfort during Portable Computer Use

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    With increased popularity of portable devices and their use outside of a traditional workstation becoming increasingly widespread, it is essential to expand on the limited research available concerning their ergonomic exposures. The goal of this study was to quantify how spine posture, muscle activation, and comfort varied depending on workstation layout, device type, and task. Twenty university aged participants completed two tasks, reading-typing and swiping, for 15-minutes blocks in eight different combination of workstation layout and device. Mean angles, muscle activation, and discomfort ratings were measured. Participants showed an increased head, neck, upper thoracic, and lumbar flexion in the lap setting. When participants used the tablet, greater head flexion was observed. Additionally, participants elicited greater muscle activation in the trapezius during the reading-typing task. Portable computer users should be conscious of the postures they adopt and consider the impact of workstation layout, device type, and task in fixed computing environments

    The Development of a Computer Operator Risk Index to Assist Computer Operators

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    Computer workstation ergonomics is well into its third decade of computer related injuries and disease. Numerous studies have been completed to inform the scientific and private communities of the threats that are posed when working at a computer. There are also multiple variables involved with attaining a computer related injury or disease, and any one of those variables, or a combination of those variables, may put a computer operator at risk. The purpose of this study was to develop a computer operator risk index (CORI), based on previous literature and containing risk variables approved by an expert panel, which is designed for relatively simple calculations. The four main risk variables were time, posture, stress, and environment. This study used 100 participants (58 females and 42 males), with a mean age of 45.8 years from an age range of 20 to 64 years, who had worked at a computer for at least 1 year and worked at least three hours per day at the computer. Not only were females and males incorporated into this study, but four ethnic backgrounds as well. Participants were asked to complete a demographic survey developed for this study, as well as a combined pain/discomfort rating chart adapted from Corlett and Bishops (1976) body chart and Borg’s (1970) CR-10 pain rating scale, a self-evaluating stress test, adapted from Yang’ (2003) self-evaluation stress test, and a Likert-type survey, which was part of the CORI form, concerning the computer operator’s work environment. The remaining sections of the CORI form were completed from observations of an expert analyst. Information contained in the demographic survey and the pain/discomfort chart was used to verify previous research that stated gender was considered a risk factor in computer operators for related illnesses or injuries. In this study Chi-Square tests showed no association (X2 = 0.036,p=0.85) in gender to show this to be true. Data from the pain/discomfort chart was combined with data taken from the CORI form and found to show a significant difference with all four major risk variables. Time, posture, stress, and environmental measures at α=.05 , showed correlation (ρ\u3c.05) with the pain measures. Furthermore, the demographic survey contained data stating that some participants had been previously medically diagnosed with a computer related injury or disease and those participants, using Chi-Square testing, were compared to the results produced from the CORI equation and found to have a significant difference and high correlation (X2 = 6.683, p = .01) . From the data retrieved and calculated in this study a logistic regression model was developed that provided the expert analyst with a means with which to measure risk to computer operators. This model included the four independent variables: time, posture, stress, and environment, which are also the four main sections of the CORI form. The CORI form is recommended for initial risk screening, but is not meant to be solely dependent upon in determining the risk of a computer operator... There are several parts of this study that in themselves may be useful. The Pain/Discomfort Rating Scale may be used to discern between severity levels of pain for computer operators, the Self-Evaluation Stress test may be used to test stress levels of computer operators, and the Computer Operator Survey may be used to collect pertinent demographic information for employers

    The effect of personalised adjustments to computer workstations on the efficiency and physical comfort of computer operators

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    The present study sought to investigate the effects of a Standard workstation, designed for “average” users, on an anthropometrically diverse sample of computer operators, and to assess whether physical and perceptual responses, as well as performance efficiency were dependent on stature. Further investigation assessed the influence of personalised adjustments to the Standard workstation, based on the anthropometric characteristics of the subjects, as well as the introduction of a custom-designed ‘floating’ wrist support, on subject responses. All subjects (n=30) were tested in each of the three workstations: Standard, Personalised and Wrist Support. For analysis of responses in the Standard workstation, subjects were divided into three groups depending on their stature: Short (1800mm). The musculoskeletal responses indicated that Tall subjects were forced to adopt the most awkward general body postures as a result of the low computer screen. However, the low screen allowed for the Short subjects to adopt the most natural general body postures, although levels of muscular activity in the upper trapezius suggest that the muscular load imposed on both Short and Tall subjects was significantly greater than that imposed on the Medium subjects. In addition, the Medium subjects’ perceptions of the Standard workstation dimensions support the fact that this workstation was better suited to users with “average” morphologies. The responses elicited in the Personalised and Wrist Support workstations were improved significantly when compared to the Standard workstation. Joint angles were more natural, upper trapezius EMG was reduced, standard of performance improved and perceptual responses indicated a diminished incidence of body and visual discomfort, as well as greater perceived satisfaction with these workstation dimensions. The improved physical responses suggest a decrease in the risk of developing cumulative trauma disorders. Although subjects were unaccustomed to the wrist support device, this workstation demonstrated a further reduction in the range of wrist angles, as well as a general positive attitude towards the concept
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