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This study was designed to evaluate localized muscular fatigue induced during visual display terminal (VDT) tasks. In the experimental paradigm used, electromyography (EMG) signals were not recorded during the VDT task but during isometric contractions in which the load imposed on the shoulder muscle was kept constant. The change in mean power frequency (MPF) and the root mean square values of EMG signals with time were explored. The correspondence between these measures and the psychological rating of localized muscular fatigue also were examined. The effectiveness of the experimental paradigm and of the measures used for evaluation of localized muscular fatigue are discussed. MPF measured during isometric contraction was found to be a sensitive measure of localized muscular fatigue. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the effects of using a forearm or wrist support on muscular load in the forearm and neck-shoulder region during work with a computer mouse. Fourteen 35- to 50-year-old healthy women who worked with a video display unit for at least 4 hr a day in an office and who also used a computer mouse for at least 2 hr a day participated in this experimental study. In the laboratory, computer mouse use with the forearm supported was compared with computer mouse use with the wrist supported. The participants edited a text table by moving symbols from one square to another in a fixed order. Each trial was a set of 64 movements. The trials were repeated 10 times in random order, 5 trials with each method of support. The dependent variable was electromyographic activity measured from muscles in the preferred lower arm and in the neck-shoulder region. Normalization to the individual mean of each participant was found to be more effective in reducing the interindividual variation than normalization to the maximal electrical activity (MEMG) obtained during isometric maximal voluntary contraction using the variation coefficient. The amplitudes normalized to the individual mean of each participant were used to evaluate the statistical significance of the difference between the methods of support. To interpret the magnitude and the practical meaning of the statistically significant differences, the corresponding mean percentages of the MEMG were used. The results of the study indicate that changing the position and support of the upper extremity affects muscular activity in the forearm and neck-shoulder region. The load on the trapezius muscle is significantly lower when the forearm is supported, and therefore such support may offer one means of preventing common disorders in the neck-shoulder region in office work. The load on the infraspinatus muscle and on forearm flexor muscles was, on the contrary, higher when the forearm was supported. The result may indicate the difficulty that workers have in adopting new hand and upper arm movements when using a computer mouse. [ABSTRACT FROM AUTHOR]

The study described in this article was designed to evaluate visual fatigue induced during video display terminal (VDT) tasks. Newly developed equipment was used that can simultaneously measure pupillary change, focal accommodation, and eye movement. The changes in these 3 physiological measures, taken during a VDT task, were used to propose an index for evaluating visual fatigue. Through multiple regression analysis, an index to describe the psychological sense of visual fatigue was obtained. In this index, the minimum pupil diameter, velocity of focal accommodation for constriction, and width of focal accommodation were included. The results suggest that visual fatigue in VDT tasks can be evaluated effectively using both pupil diameter and focal accommodation. The index can be used to assess visual fatigue induced during a VDT task if the following 3 conditions are satisfied: 1. Head movement is limited and infrequent. 2. The task requires focal accommodation. 3. During the task, there is no outstanding change in the lighting environment such as luminous intensity or brightness. [ABSTRACT FROM AUTHOR]

This article is a review of the international literature regarding health consequences for visual display unit (VDU) workers. The 2 main problems reported by VDU workers, visual discomfort and musculoskeletal pain, are particularly focused. Important factors for designing the lighting system and workplace are given. A procedure for optometric corrections is discussed. This article emphasizes the importance of multidisciplinary cooperation to reduce visual discomfort and musculoskeletal pain. [ABSTRACT FROM AUTHOR]

This article examines the effect of physical ergonomic work conditions on occupational health in video display terminal (VDT)-intensive work settings. A longitudinal intervention field study was conducted in a catalog retail service organization in the Midwest to explore the impact of ergonomic interventions. There were 3 levels of ergonomic interventions, each adding incrementally to the previous one. The 1st level was ergonomic training for all VDT users accompanied by workstation ergonomic analysis leading to specific customized adjustments (Group C). The 2nd level added specific workstation accessories supplied by Details, Inc. if the analysis indicated a need for them (Group B). The 3rd level added a Steelcase Criterion Trademark 453 Series chair (Group A). Health data were gathered from 80 volunteer participants by administering a survey before (baseline), 6 months after, and 12 months after interventions were put in place. The findings show that neck, back, and shoulders as well as wrists stand out in terms of self-reported musculoskeletal pain in VDT-intensive work. Reductions in self-reported musculoskeletal discomfort were found for all 3 levels of incremental ergonomic interventions. The number of cases showing improvement in health over time was significant for intervention Groups A and B, but not C. [ABSTRACT FROM AUTHOR]

The relation between psychological mood state, psychosocial aspects of work, and musculoskeletal discomfort was examined using a questionnaire survey of 505 office employees whose jobs required intensive use of video display terminals. Logistic and linear regression analyses demonstrated significant relations between the psychological mood state of stress and musculoskeletal discomfort. Linear regression analysis showed a significant relation between some psychosocial aspects of work and the psychological mood state of stress. The results suggest that an individual's psychological state and characteristics of jobs have important relations to musculoskeletal health. The cross-sectional study design precluded interpretation regarding the temporal nature of these relations. [ABSTRACT FROM AUTHOR]

In a field study, a newly developed mouse that gives the operator a more neutral forearm position was compared with a traditional mouse using a more pronated forearm. After using the new mouse for 6 months, a significant reduction was reported regarding pain intensity and frequency for wrist/hand, forearm, shoulder, and neck (p >/= .009). The control group using the traditional mouse reported only small changes in the pain level (p >/= .24). Total duration of pain the last 6 months was also significantly improved for the shoulder and forearm in the intervention group, whereas no such changes were observed in the control group. These results clearly indicate the importance of using a computer mouse with a more neutral position of the forearm. [ABSTRACT FROM AUTHOR]

This study examines the effects of text and background color combination and typography of characters on visual performance and visual fatigue of individuals working on a visual display termina] (VDT). Correct percentage of performance, critical fusion frequency, near point of convergence, subjective visual fatigue, and preference ranking of color combinations of 40 participants were collected and analyzed. Color combination had no significant effects on visual performance. Typography significantly affected performance. Aesthetically pleasing but more cluttered characters were detrimental to visual performance. Characters of higher frequency and fewer strokes were identified more accurately. Participants also showed differential preference for color combinations. Red-on-green was ranked inferior to color combinations generally used in computer software. Participants showed no visual fatigue during the VDT work. [ABSTRACT FROM AUTHOR]

Explores the situations and activities during which video display terminal operators' musculoskeletal discomforts arose. Engagement of the study groups in highly computerized office work; Preparation of an instrument for in-depth interview to examine how the individual was coping with any musculoskeletal discomfort; Relation of the discomfort to work and overall life situation of the interviewee.

Examines the underlying hierarchical structure and validity of a health checklist that assesses the Video Display Terminal (VDT) operator health. Use of the checklist in many studies of VDT workers; Performance of the factor analyses of the health checklist; Analysis of the convergent and discriminant validity of the nine-factor solution.

Examines the work environment and health of Swedish government employees who use visual-display terminals. Relationship between work organization and mental or somatic symptoms; Tasks preponderant among women employees; Number of hours per day beyond which the incidence of symptoms rose sharply.

Investigates alternative designs on video display terminals. Variation of contours and borders; Result for angled and straight contours and explicit and implicit borders; Ambiguities in apparent motion; Production of animation in mimic displays.

Studies the visual problems of video display terminal work through the analysis of visual functions in two experiments. Result of the eye movement analysis; Correlation between the velocity of lens accommodation and the subjective visual comfort while viewing different displays; Appropriateness of using a positing-type cathode-ray tube.

This study tested the hypothesis that asynchrony between the work rhythm and a worker's internal physiological rhythms may be a source of stress in repetitive computer work. Experienced typists (N= 20) entered lines of numeric data using a video display terminal in a simulated office environment. Each day of the 2-day experiment consisted of six 40-min work periods. The work rhythm was varied between work periods by adjusting the field length of data entry lines (3-13 characters). Breathing and cardiac responses were monitored continuously throughout work periods, and a mood survey was administered at the end of each work period. The extent of synchronization between (1) breathing response and the work rhythm, (2) cardiac response and the work rhythm, and (3) all three measures (breathing and cardiac responses, and the work rhythm) was scored for each work period using crossspectral analysis. Synchronization scores were then evaluated as predictors of mood state and physiological response using multiple regression techniques. [ABSTRACT FROM AUTHOR]

A longitudinal study on the use of visual display terminals (VDTs) was conducted with questionnaire data obtained 1981 and in 1987-1988 from a cohort of office workers. The use of VDTs became more widespread in these offices during the intervening time period, but the time spent by individuals working at VDTs showed no general increase. The data suggested that VDT use was related to the risk of developing eye discomforts and hand and wrist problems. For skin problems and headache, risks for VDT and non-VDT users were fairly similar, but indications of increased risks were found for certain groups and situations. The risks o[ developing neck, shoulder, shoulder joint, or upper arm problems were high for both VDT and non-VDT users, but there were, in this study, no convincing suggestions that these risks were higher for VDT users compared to nonusers. [ABSTRACT FROM AUTHOR]

Urinary excretions of catecholamines in young volunteers were examined during VDT work to evaluate whether VDT work affected sympathetic and adrenal function. The time course of work performance was also monitored. The excretion of catecholamines did not increase after the reference work with hard copy. Adrenaline excretion tended to increase after VDT work with large print, although the noradrenaline excretion did not change. After VDT work with small print, noradrenaline excretion increased significantly; and adrenaline excretion tended to increase. The work speed of the VDT group using small print in the early period was slower than that of the hardcopy group or the VDT group using large print, but the difference diminished in the late period. Abrupt decreases in work speed, considered a result of exhaustion, did not appear in any group. These results suggest that VDT work may act as a stronger workload for the sympathoadrenal system than hard-copy work, and it also suggests that VDT workload may be worsened by small print size. [ABSTRACT FROM AUTHOR]

The aim of the study is to evaluate the characteristics of various kinds of VDT operations by using an analysis of eye movements and examining the distribution of gaze fixation points. Eye movements were detected by the 'corneal reflection technique' and analyzed in terms of (a) tracing eye movements, (b) forming a matrix of fixation frequency, (c) describing the fixation area, and (d) adjusting the fixation vector. Five VDT operators involved in the development of computer software were selected as the subjects, with an average age of 24.8 years. Eye movements of the subjects were intermittently recorded throughout an 8-hr working day. It was confirmed that an analysis of eye movements can be a meaningful way to characterize certain ergonomic aspects of VDT operations. [ABSTRACT FROM AUTHOR]

Examines the dominant wavelength and stimulus purity for Visual Display Terminal display color in terms of readability. Definition of readability; Identification of an easily readable stimulus purity for each dominant wavelength; Employment of paired comparisons method to examine different colors.

Assesses the amount of visual display terminal (VTD) work from an organizational perspective. Impact of VTD use on employees; Consequences of terminal work on various aspects of physical and psychological health; Patterns of VTD use within the organizational unit.