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Biomedical subjects

Guy G Simoneau

Publications and source records attributed to Guy G Simoneau.

4 recordsLinked to original sources
PubMed2006

Effect of keyswitch design of desktop and notebook keyboards related to key stiffness and typing force.

This study aimed to compare and analyse rubber-dome desktop, spring-column desktop and notebook keyboards in terms of key stiffness and fingertip typing force. The spring-column keyboard resulted in the highest mean peak contact force (0.86N), followed by the rubber dome desktop (0.68N) and the notebook (0.59N). All these differences were statistically significant. Likewise, the spring-column keyboard registered the highest fingertip typing force and the notebook keyboard the lowest. A comparison of forces showed the notebook (rubber dome) keyboard had the highest fingertip-to-peak contact force ratio (overstrike force), and the spring-column generated the least excess force (as a ratio of peak contact force). The results of this study could aid in optimizing computer key design that could possibly reduce subject discomfort and fatigue.

Adult↗
PubMed2004

Design features of alternative computer keyboards: a review of experimental data.

Design of computer keyboards no longer is limited to the flat keyboards that are typically shipped with personal computers. Keyboards now exist that are split into halves and these halves can be slanted away from each other (creating a triangle between the halves), sloped downward toward the visual display terminal, tilted upward like a tent, or simply separated. These design features are intended to alleviate discomfort and possible musculoskeletal disorders that have been suggested to be associated with the extensive use of conventional computer keyboards. The geometry of conventional keyboards requires the wrists to be in 10 degrees to 15 degrees of ulnar deviation and 20 degrees of extension and the forearms to be nearly fully pronated while typing. A review of the available experimental data collected on 10-digit touch typists indicates that (1) keyboards with a slant angle (half of the opening angle) of 10 degrees to 12.5 degrees or keyboards with halves separated to approximately shoulder width are both effective in placing the wrist in near neutral (0 degree) ulnar/radial deviation when typing, (2) wrist extension can be reduced to near neutral (0 degrees) when a keyboard with a negative slope of 7.5 degrees is used, contingent on the wrist rest also sloping with the keyboard, and (3) tilting the keyboard halves 20 degrees to 30 degrees is effective in reducing forearm pronation to approximately 45 degrees. These studies also indicate that experienced 10-digit touch typists readily adapt (within 10 minutes) to these individual alternative keyboard features, and can type with approximately the same speed and accuracy as with the conventional keyboard. While placing the wrist and forearm in a more neutral position could, in theory, reduce the incidence of musculoskeletal disorders, randomized controlled trials are necessary before strong recommendations can be made on the effectiveness of alternative keyboards for the prevention and/or treatment of musculoskeletal disorders. In the absence of these randomized controlled trials, the information in this article provides preliminary guidance to clinicians in their evaluation of computer keyboards and workstations and their recommendations to patients.

Computer Peripherals↗
PubMed2003

Effect of computer keyboard slope on wrist position and forearm electromyography of typists without musculoskeletal disorders.

BACKGROUND AND PURPOSE: Positioning a computer keyboard with a downward slope reduces wrist extension needed to use the keyboard and has been shown to decrease pressure in the carpal tunnel. However, whether a downward slope of the keyboard reduces electromyographic (EMG) activity of the forearm muscles, in particular the wrist extensors, is not known. SUBJECTS AND METHODS: Sixteen experienced typists participated in this study and typed on a conventional keyboard that was placed on slopes at angles of 7.5, 0, -7.5, and -15 degrees. Electromyographic activity of the extensor carpi ulnaris (ECU), flexor carpi ulnaris (FCU), and flexor carpi radialis (FCR) muscles was measured with surface electrodes, while the extension and ulnar deviation angles of the right and left wrists were measured with electrogoniometers. RESULTS: Wrist extension angle decreased from approximately 12 degrees of extension while typing on a keyboard with a 7.5-degree slope to 3 degrees of flexion with the keyboard at a slope of -15 degrees. Although the differences were in the range of 1% to 3% of maximum voluntary contraction (MVC), amplitude probability distribution function (APDF) of root-mean-square EMG data points from the ECU, FCU, and FCR muscles varied across keyboard slopes. DISCUSSION AND CONCLUSION: Wrist extension decreased as the keyboard slope decreased. Furthermore, a slight decrease in percentage of MVC of the ECU muscle was noted as the keyboard slope decreased. Based on biomechanical modeling and published work on carpal tunnel pressure, both of these findings appear to be positive with respect to comfort and fatigue, but the exact consequences of these findings on the reduction or prevention of injuries have yet to be determined. The results may aid physical therapists and ergonomists in their evaluations of computer keyboard workstations and in making recommendations for interventions with regard to keyboard slope angle.

Adult↗