Sitting Posture and Neck and Shoulder Muscle Activities at Different Screen Height Settings of the Visual Display Terminal

• Published in: Industrial Health Vol. 35; no. 3; pp. 330 - 336
• Main Authors: VILLANUEVA, Maria Beatriz G., JONAI, Hiroshi, SOTOYAMA, Midori, HISANAGA, Naomi, TAKEUCHI, Yasuhiro, SAITO, Susumu
• Format: Journal Article
• Language: English
• Published: Japan National Institute of Occupational Safety and Health 01.07.1997
• Subjects: Adult; Analysis of Variance; Computer Terminals; Electromyography; Electromyography (EMG); Female; Head Movements - physiology; Humans; Male; Middle Aged; Neck extensor muscle; Neck Muscles - physiology; Posture; Screen height; Shoulder - physiology; Space life sciences; Statistics, Nonparametric; Trapezius muscle; Visual display terminal (VDT)
• ISSN: 0019-8366; 1880-8026
• DOI: 10.2486/indhealth.35.330

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 120cm. 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.