Authors (including presenting author) :
Jenna Ng (1), Heidi Wong (2), Amanda Lam (3), Cherry Au (4), Catherine Fung (5), Josephine Wong (6), Kenneth Fong (6)
Affiliation :
1 Pamela Youde Nethersole Eastern Hospital
2 Kwai Chung Hospital, Hong Kong
3 Queen Mary Hospital, Hong Kong
4 Tai Po Hospital, Hong Kong
5 the Boys’ and Girls' Clubs Association, Hong Kong
6 Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hong Kong
Introduction :
Office ergonomics serves as a safety guideline for office workers which aims at sustaining health and productivity at work. Few attempts to date have been made to verify the effectiveness of wrist neutral position and the wrist pad by taking into account the relationship between wrist position and level of forearm muscle activity.
Objectives :
This study aims at investigating the effects of various wrist positions on computer keyboard typing, including: 1) neutral position, and 2) the application of wrist pad.
Methodology :
This study has recruited 18 female participants aged 20-25 with right-hand dominance. Participants in this study typed in a standard computer workstation in 4 different conditions in a randomised sequence: wrist neutral with or without wrist pad, and wrist 30’ extension with or without wrist pad. Electromyographic (EMG) activity of the Extensor Digitorum Communis (EDC) and Flexor Digitorum Superficialis (FDS) muscles was measured with surface electrodes, while wrist neutral and 30 ’extension angles were measured with goniometers. Typing speed and accuracy were also measured for each subject in each trial using an online software. After the typing task, all participants were asked to fill in a psychophysiological questionnaire to evaluate the subjective feeling during typing at different wrist angles and wrist support conditions
Result & Outcome :
Wrist neutral position in keyboard typing has resulted in significant reduction in muscle activity of EDC only, while the use of wrist pad has significantly reduced muscle activity of EDC and FDS in neutral position.
Conclusions :
This study found that wrist neutral position and the use of wrist pad have both significantly reduced the muscle activity of forearm extensor. The results validate ergonomic suggestion of wrist positions in keyboard typing. This may help occupational therapists and ergonomists inter evaluations of computer keyboard workstations, thereby preventing musculoskeletal disease at workplace and enhancing office ergonomics.
