Consideration of the literature survey indicates that video display terminal (VDT) operators tend to have a high incidence of musculoskeletal problems, visual fatigue, and job stress. Although a number of ergonomic improvements in workstation design and work environment can help to reduce these problems, a proper work-rest schedule deserves consideration since it is easily applicable and inexpensive. The objective of this study was to compare the work-rest schedules for VDT operators considering data entry and mental arithmetic tasks. An experiment was conducted with 10 male college students as participants. The methodology included a discomfort questionnaire and performance measures. The independent variables were the work-rest schedule (60-minute work/10-minute rest, 30-minute work/5-minute rest, and 15-minute work/micro breaks) and the type of task (data entry and a mental arithmetic task). The results were analysed using multiple analysis of variance followed by separate analyses. The 15/micro schedule resulted in significantly lower discomfort in the neck, lower back, and chest than the other schedules for data entry task. The 30/5 schedule followed by 15/micro schedule resulted in the lowest eyestrain and blurred vision. Discomfort in the elbow and arm was the lowest with the 15/micro schedule for the mental arithmetic task. The 15/micro schedule resulted in the highest speed, accuracy, and performance for both of the tasks, compared with the 60/10 and 30/5 schedules. The data entry task resulted in significantly increased speed, accuracy, and performance, and lower shoulder and chest discomfort than the mental arithmetic task.

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An experiment was conducted with ten male subjects who performed data entry and mental tasks. Scores of subjective discomfort questionnaire, speed, accuracy, and performance of the subjects and electromyography measurements from trapezius and flexor carpi radialis muscles were recorded. Three diierent work-rest schedules were applied: 60-minute work/lO-minute rest, 30-minute work/S-minute rest, and for the third schedule, the subjects received four breaks from Video Display Terminal (JDT) work each hour additional to a 1Cminute break after two hours. Subjects were asked to enter randomly created alphanumeric data (last name, tirst name, and phone number) for data entry task and to solve randomly created addition and subtraction problems as mental task. Mental task resulted in a higher psychological discomfort, lower physical discomfort, and lower performance than data entry task. The results of the study suggest that the 15/micra schedule is superior to the longer and itiequent rest break schedules considering upper extremity discomfort, eyestrain, speed, accuracy, performance, and the load in trapezius muscle for both data entry and mental tasks.

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