Journal of Occupational Health
Online ISSN : 1348-9585
Print ISSN : 1341-9145
ISSN-L : 1341-9145
Impact of Keyboard Typing on the Morphological Changes of the Median Nerve
Ping Yeap LohWen Liang YeohHiroki NakashimaSatoshi Muraki
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JOURNALS FREE ACCESS Advance online publication

Article ID: 17-0058-OA


Objectives: The primary objective was to investigate the effects of continuous typing on median nerve changes at the carpal tunnel region at two different keyboard slopes (0° and 20°). The secondary objective was to investigate the differences in wrist kinematics and wrist anthropometric changes when typing at the two different keyboard slopes.

Methods: Fifteen healthy right-handed young men were recruited. A randomized sequence of the conditions (control, typing I, and typing II) was assigned to the participants. Wrist anthropometric measurements, wrist kinematics data and ultrasound examination to the median nerve was performed at designated time block.

Results: Typing activity and time block do not cause significant changes on the wrist anthropometric measurements. The wrist measurements remained similar across all the time blocks in the three conditions. Subsequently, the wrist extension and ulnar deviation were significantly higher in both the typing I and typing II conditions than in the control condition for both wrists (p < 0.05). Additionally, the median nerve cross-sectional area (MNCSA) significantly increased in both the typing I and typing II conditions after the typing task than before the typing task. The MNCSA significantly decreased in the recovery phase after the typing task.

Conclusions: This study demonstrated the immediate changes in the median nerve after continuous keyboard typing. Changes in the median nerve were greater during typing using a keyboard tilted at 20° than during typing using a keyboard tilted at 0°. The main findings suggest wrist posture near to neutral position caused lower changes of the median nerve.

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2017 by the Japan Society for Occupational Health