[Comparison of muscular load between normal handwriting and constrained writing forced by optical character reader...

Optical character readers (OCR) were introduced into an office as input devices for a computer system. In order to input data in to the system, workers of this office had to write down the data on sheets of specially formatted paper, called OCR cards. Some workers engaged in this task complained of symptoms of occupational cervicobrachial disorders (OCD). Observation suggested that the constrained motion of writing on OCR cards may cause such symptoms. Therefore, in order to prevent OCD, the writing motion was analyzed. The electromyogram of the upper extremities and shoulders was also compared between normal handwriting and constrained writing on the OCR cards in laboratory studies. The results were as follows. 1. Writing time per letter for the OCR cards was longer than that for normal handwriting. 2. Discharge of muscles observed through electromyogram was larger per letter for the OCR cards than for the normal handwriting. 3. Discharge from the trapezius per unit time for the OCR cards was rather large. This phenomenon showed that the workload of constrained writing was heavier than that of normal handwriting. The results suggests that more careful preventive measures for OCD should be promoted in comparison with ordinary clerical tasks.