Effect of Setup Configurations of Split Computer Keyboards on Wrist Angle

Alternative computer keyboards whose halves can be slanted toward each other can reduce a risk factor (ulnar deviation) for work-related musculoskeletal disorders (WMSDs) affecting the upper limbs. Two questions that computer keyboard operators face when using keyboards that can be separated into halves (split keyboards) are: (1) At what angle should the keyboard halves be opened? and (2) At what distance apart should the keyboard halves be placed? The objective of this study was to investigate the effects of the opening angle and separation distance between halves of a split keyboard on wrist ulnar deviation and typing efficiency. Methods. Eleven experienced computer keyboard operators participated in this study and used a split keyboard that was set up in a conventional (nonsplit) format and also in 3 alternative configurations: (1) centers of keyboard halves were separated at 20-cm distance, (2) keyboard halves were separated half of the distance of shoulder width, and (3) keyboard halves were separated at shoulder width distance. Results. The 3 alternative configurations resulted in ulnar deviation of both wrists that were less than ulnar deviation from typing on a conventional setup. There were no differences in ulnar deviations among the 3 alternative configurations. Discussion and Conclusion. The results of this research provide physical therapists and ergonomists with a set of configurations of a split keyboard that they can recommend to their patients or clients. All of the alternative configurations of the split keyboard are beneficial in promoting a neutral wrist position, which theoretically would decrease exposure to WMSDs such as tenosynovitis in the wrist and carpal tunnel syndrome. [Marklin RW, Simoneau GG. Effect of setup configurations of split computer keyboards on wrist angle. Phys Ther. 2001;81:1038 –1048.

Effect of Computer Keyboard Slope on Wrist Position and Forearm Electromyography of Typists Without Musculoskeletal Disorders

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. 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. [Simoneau GG, Marklin RW, Berman JE. Effect of computer keyboard slope on wrist position and forearm electromyography of typists without musculoskeletal disorders. Phys Ther. 2003;83:816–830.

Writing With(out) Pain: Computing Injuries and the Role of the Body in Writing Activity

This article uses the lens of computer writing injuries to explore writing as an embodied activity. We use philosopher Mark Johnson\u27s five-part definition of embodiment to develop an analysis that examines the physical, flesh-and-blood aspects of writing in addition to the social and cultural aspects of embodied activity. With this framework, we show the limits of purely technological solutions to writing injuries (like ergonomic keyboards) and explore the difficulties of including somatic training in the writing classroom. Rather than prescribing a single solution, we propose that these injuries require multifaceted infrastructural changes, and point to the benefits of approaching writing with mindfulness. We conclude by suggesting ways that writing instructors and scholars can use this framework to rethink the role of the body in writing activity

Effects of a Multitouch Keyboard on Wrist Posture, Typing Performance and Comfort

Alan Hedge Geri GayThe design of computer keyboards is rapidly evolving as portable computing becomes increasingly ubiquitous due to wireless networking and the increased popularity of personal digital assistants and notebook computers. However, there is a balance between mobility and productivity, in terms of text-entry accuracy and speed, which needs to be maintained as computer keyboards become smaller and slimmer through the introduction of ultra low-profile designs. In addition, the ergonomic benefits, in terms of the reduction of awkward wrist postures and user comfort, of ultra-low profile designs are unclear. This study tests a new prototype ultra-low profile MultiTouch keyless keyboard (MTK) that uses a MultiTouch surface to create an extremely thin typing environment that requires no force to register a keystroke and allows mousing and gestural input on the same surface. In this study, the MTK was tested against a conventional keyboard (CK) for typing speed, accuracy, wrist postures and user comfort. It was hypothesized that the lack of key travel would increase speed and accuracy, while the ultra-thin design would reduce the amount of wrist extension, which could decrease the risk of a wrist injury or other hand and wrist musculoskeletal disorder. Finally, it was hypothesized that there would be a significant short-term learning effect on typing speed and accuracy for the MTK. A laboratory experiment was conducted with 6 males and 6 females typing using two QWERTY keyboard designs: a CK and a MTK. Subjects visited the lab for 1.5 hours for 2 non-consecutive days in the same week, for a total of 3 hours. Each visit consisted of eight randomly assigned 7.5-minute typing tasks of text passages of similar difficulty and identical length. Quantitative measures of typing speed and accuracy were collected using Typing Quick and Easy 13.0 and qualitative measures of user preference and comfort were gathered by self-report questionnaires. A wrist glove electrogoniometer system was used to record right-hand wrist positioning data, which was analyzed to assess the risk of injury. The two keyboards were evaluated in a repeated measures within-subjects factorial design. Subjects, typed slower (F1,11 = 41.86, p=0.000) and less accurately (F1,11 = 23.55, p=0.001) on the MTK during the typing tasks. Subjects preferred the CK and reported a higher level of ease (F1,11 = 49.732, p=0.00) and enjoyment (F1,11 = 51.129, p=0.00) during its use. Mean wrist extension was lower for the MTK (F1,11= 10.205, p=0.000) while radial and ulnar deviation did not differ significantly between the two keyboards. The MTK had a lower percentage of highest-risk wrist extension (F1,11= 6.437, p=0.028), and conversely, a higher percentage of neutral wrist posture (F1,11= 12.947, p=0.004). A significant positive linear trend was observed across the within-subjects scores for speed (F1,11= 9.308, p=0.011) and accuracy (F1,11= 11.903, p=0.005) across tasks in the MTK condition. Limitations to this study include practice effects, due to the naive subjects' lack of training on the MTK and the limited duration of exposure to this novel keyboard. Fatigue effects may have also been a factor, even though the experimental conditions were spread out over two non-consecutive days in the same week. Future research directions include additional testing of the unique mousing and gestural capabilities of the MTK. Other research suggests that practice and extended exposure to the MTK may raise performance to comparable levels associated with CK devices.College of Human Ecology, Cornell Universit

Development of an Ergonomic Desk and Support for Optimal Keyboard Angle in the Sitting and Standing Workstation

With the proliferation of computers in homes and workplaces, the keyboard has become an integral part of our daily lives, and it is difficult to imagine using a computer without one. Given the high prevalence of WMSDs among computer users and the growing global computer workforce, concerns exist about the escalation of computer related injury with Carpal tunnel syndrome (CTS) being one of the most reported WMSDs among office workers. The forceful and repetitive movements of the hand and wrist, prolonged use of the hand and wrist and a non-neutral or awkward wrist posture (where there is a migration from a neutral flexion/extension position) are some of the causes of CTS among office workers. If these known risks are not addressed appropriately, this injury will inhibit a person’s ability to perform work effectively. The purpose of this study is to determine the optimal range of keyboard angles for sitting and standing positions based on wrist posture, forearm muscle activities and user preference. Keyboard location in relation to user position and distance will be identified for both sitting and standing postures. 30 volunteers with an above 40wpm typing speed participated in this study with wrist posture, muscle activity, typing performance, distance to place keyboard and user preference as dependent variables were measured. A 2-way ANOVA for repeated measure was performed using the SPSS software for analyzing the results of the dependent variables. Results show that, although user prefer to use positive keyboard angle, the negatively tilted keyboard is more ergonomically friendly at both sitting and standing workstations as compared to the standard keyboard angle, reducing muscle activity and awkward wrist posture while maintaining performance. Findings from this study should provide a useful framework for ergonomics practice and policy evaluation, and we expect that an office workstation can be improved for workers to reduce their risk of developing WMSDs, specifically CTS, with an ergonomic desk for sitting and standing workstations, including a universally adjustable support attached to the desk for sitting and standing workstation

Ergonomics of using a mouse or other non-keyboard input device

Ten years ago, when the Health and Safety (Display Screen Equipment) Regulations (HSE, 1992) were drafted, the majority of computer interaction occurred with text driven interfaces, using a keyboard. It is not surprising then that the guidance accompanying the DSE Regulations included virtually no mention of the computer mouse or other non-keyboard input devices (NKID). In the intervening period, graphical user interfaces, incorporating ‘windows, icons and pull down menus’ (WIMPS), with a heavy reliance on pointing devices such as the mouse, have transformed user computer interaction. Accompanying this, however, have been increasing anecdotal reports of musculoskeletal health problems affecting NKID users. While the performance aspects of NKID (e.g. accuracy and speed) have been the subject of detailed research, the possible implications for user health have received comparatively little attention. The research presented in this report was commissioned by the Health and Safety Executive to improve understanding of the nature and extent of NKID health problems. This investigation, together with another project examining mobile computing (Heasman et. al., 2000), was intended to contribute to a planned review and updating of the DSE Regulations and accompanying guidance

A comparison of a Klockenburg style split keyboard and a standard PC keyboard on typing speed and posture

The current study compares biomechanical and productivity outcomes related to the use of a Klockenburg (split and angled) style keyboard as opposed to the use of a standard PC 101 style keyboard among office workers. The study used 10 subjects (5 male and 5 female) who were employees of a large insurance company. Subjects were categorized by job classification, including 5 exempt and 5 nonexempt employees. Each subject was evaluated on both of the keyboards in a laboratory setting after three weeks of familiarization with the keyboards at their workstation. Productivity was measured as words per minute. In the lab, biomechanical outcomes included angular measures of forearm pronation/supination, wrist flexion/extension, wrist radial/ulnar deviation and neck angle. Lab results showed that the Klockenburg keyboard negatively impacted productivity and neck posture, while forearm pronation/supination and wrist radial/ulnar deviation were in more neutral positions. There was no significant difference in wrist extension between the two keyboards. In the field, the Klockenburg keyboard did not impact productivity

WRIST BIOMECHANICS AND ULTRASONOGRAPHIC MEASURES OF THE MEDIAN NERVE DURING COMPUTER KEYBOARDING

Keyboarding is a highly repetitive daily task and has been linked to musculoskeletal disorders of the upper extremity. However, the effect of keyboarding on median nerve injuries is not well understood. The purpose of this study was to determine whether continuous keyboarding can cause acute changes in the median nerve and whether these changes are correlated with wrist biomechanics during keyboarding. Ultrasound images of the median nerve from forty healthy volunteers were captured at the levels of the pisiform and distal radius prior to and following a prolonged keyboarding task (i.e., one hour of continuous keyboarding). Images were analyzed by a blinded investigator to quantify the median nerve characteristics. Changes in the median nerve ultrasonographic measures as a result of continuous keyboarding task were evaluated and compared to the hand and wrist biomechanical variables, which were collected simultaneously. Cross-sectional areas at the pisiform level were significantly larger in both dominant and non-dominant hands following the keyboarding task. Swelling ratio was also significantly greater in both hands after 30 and 60 minutes of keyboarding when compared to the baseline measures. Both cross-sectional area and swelling ratio, however, decreased after 30 minutes of manual rest. These acute changes were positively correlated to biomechanical variables of wrist, including wrist flexion and tendon travel. We were able to detect acute changes in the median nerve ultrasound characteristics following one hour of computer keyboarding. These changes were significantly correlated to the wrist biomechanics. The findings suggest that keyboarding has an impact on the median nerve. Further studies are required to understand this relationship, which would provide insight into the pathophysiology of median neuropathies such as carpal tunnel syndrome