Computer Mouse Use Research Articles

DISTURBED PROPRIOCEPTION FOLLOWING COMPUTER MOUSE USE

Changes in proprioception (movement and position perception), facilitated by alterations in muscle spindle afferent activity, arise following repetitive muscle activity, especially if fatigue ensues. Consequently, a hypothesis was put forth that work-related musculoskeletal disorders (both in the genesis and spread of muscle pain) might be attributed to diminished proprioceptive function. PURPOSE: To determine the effect of computer mouse use on proprioception. METHODS: Position sense acuity of the wrist joint for 23 normal volunteers (11 females and 12 males) was determined before and after a laboratory model of repetitive mouse use entailing painting small squares on the computer screen uninterrupted for 45 minutes. Wrist position sense was determined by noting the angular error for subjects actively reproducing a series of 15 test trials randomly displaced between 0○ and 30○ of flexion, while starting at 30○ of extension. The variability of error (VE) (i.e. standard deviation of the 15 trials) was computed as the assessment variable of accuracy. In addition, subjective fatigue was assessed using the Borg scale before, after and for each 5 min-interval during the painting protocol. RESULTS: A 2-way ANOVA revealed an increase in VE following mouse use for the group (p < 0.05), but no difference between gender was detected. Fatigue ratings increased throughout the painting protocol for the group (p < 0.001); furthermore a significant interaction was found between gender (p < 0.05), which displayed as males exhibiting a steep increase in the first 10 minutes followed by a plateau, while for females a constant linear increase was observed throughout. CONCLUSIONS: Since optimal motor control is largely dependent on proprioception, it may be implied that extended mouse use could lead to increased workload, thereby increasing intramuscular metabolites and/or inflammatory substances which would further impact proprioception (i.e. an unfavorable cycle of events). Thus, the current findings may provide insight into the poorly understood mechanism behind computer related musculoskeletal disorders. Supported in part by the Swedish Council for Work Life Research, and technically by Monica Edstrom and Majken Rahm.

Influence of memory demand and contra lateral activity on muscle activity

Computer mouse work often includes memory demands and contra lateral activity. This study simulated video display unit (VDU) mouse-work and the focus was on forearm muscle activity as a result of standardised postural loads, memory demands and contra lateral activity. Surface and intramuscular electromyography (EMG) were recorded from the right forearm muscles during finger elevation and rest with and without memory demands and with and without contra lateral activity i.e. activity of the left hand. In most situations, memory demand increased activity in the m. extensor carpi radialis brevis and m. flexor digitalis superficialis. Also contra lateral activity increased activity in situations with and without memory demands. While surface EMG level of the m. extensor digitorum communis did not increase during memory demands, intramuscular EMG level increased when memory demands and contra lateral activity was combined. Influence of memory demands and contra lateral activity were most pronounced, in situations where activity levels were small. We presume that it is not only prolonged time of active computer mouse use that is a risk for development of musculoskeletal disorders, but also the time when people interact with the computer mentally or with the ‘non-mouse hand’, while resting their ‘mouse-hand’ on the mouse.

The prevalence of neck and upper extremity musculoskeletal symptoms in computer mouse users

Computer pointing devices such as the mouse are widely used. Despite this, the relationship between musculoskeletal symptoms and mouse use has not been established. The aim of this cross-sectional study was to determine whether a relationship existed between computer mouse use and musculoskeletal symptoms in a sample of 270 computer mouse users. Factors demonstrating a significant association with symptoms were entered into a step-wise multiple logistic regression, adjusting for age and sex and controlling for potential interdependence between variables. No relationship was found between hours of mouse use per day and reported symptoms. A relationship was found between the variable of arm abduction which is specific to mouse use and symptoms in the neck. Relationships were found between non-mouse-specific risk factors such as stress, screen height and shoulder elevation. The findings of this study support the hypothesis that mouse use may contribute to musculoskeletal injury of the neck and upper extremity. Mouse users are exposed to the same recognised risk factors associated with keyboard use as well as the additional risk factor of arm abduction during mouse use. Relevance to industry Computer keyboard use has been associated with musculoskeletal injuries. Most people now use a pointing device such as the mouse to supplement the computer keyboard. Additional risk factors related to mouse use have the potential to increase prevalence of computer-related injuries.

Computer Workplaces for Primary School Children - What about Ergonomics?

Computer related RSI before 20 years of age? This rather provocative question put focus on the increasing number of children and young people requiring treatment for muscular problems, particularly from the shoulder and arm region, problems that are related to the use of computer mouse and keyboard. The usage of computers has increased during the last years and particularly in the ages from 7 to 10. Young children are using computer in schools, in spare time activities outside schools and in the homes. The number of hours that children are using computers will most probably increase even further as many schools are prioritising investments in this area. The objectives with this study were to create a survey of computer work place design in the school environment and to evaluate this from an ergonomic and physical point of view, regarding the situation for both pupils and teachers. The study has pointed out that there is a limited ergonomic knowledge among teachers and other responsible people working in schools. This lack of awareness among the majority of teachers is affecting two different problems; firstly the physical strain children are exposed to when using computers due to bad workplace design and secondly it gives the children a lack of awareness of the importance of ergonomic aspects in workplace design. The saying “We do not train for school, we train for life” is very true, particularly in this case. To support teachers and other people in the schools, responsible for the use of and training with computers, a hand book, based on the outcome of the study, has been produced. The handbook contains headlines as Computer ergonomics in the school environment; To the teacher; To the student; Checklist and finally a short chapter: To you that only have the time to read two pages. The handbook should be distributed free of charge to all Swedish schools.

Shoulder muscle activity in young and older people during a computer mouse task

Objective. Assessment of the age effect in relation to computer work. Background. Increasingly, more older people are using computers, while hardware and software are not designed with special consideration of their needs. Methods. Eight young and nine older females performed different computer mouse tasks. Shoulder muscle activity was recorded from the right deltoid muscle, right and left upper trapezius muscle, and the neck extensor muscles. Results. Mean trapezius muscle activity was significantly higher in the older people (2.8%/3.7% EMG max for R/L) compared to the young (1.1%/1.2% EMG max). There was a tendency to a higher activity in the older people for the deltoid muscle and the neck extensor muscles. There were small differences in shoulder muscle activation levels between mouse actions, target directions, and between precision demands. Conclusions. Shoulder muscle activity during computer work is affected by age, but only to a minor extent by the type of computer mouse task. The deltoid and the trapezius muscle activities are low during computer mouse use when there is efficient forearm support by the table. Relevance An increasing number of people use computers for hours every day. Intensive use of computers increases the risk of development of work-related musculoskeletal symptoms in the shoulder region.

Effects of computer mouse design and task on carpal tunnel pressure

Computer mouse use has become an integral part of office work in the past decade. Intensive mouse use has been associated with increased risk of upper extremity musculoskeletal disorders, including carpal tunnel syndrome. Sustained, elevated fluid pressure in the carpal tunnel may play a role in the pathophysiology of carpal tunnel syndrome. Carpal tunnel pressure was measured in 14 healthy individuals while they performed tasks using three different computer mice. Participants performed a multidirectional dragging (‘drag and drop’) task starting with the hand resting (static posture) on the mouse. With one mouse, an additional pointing (‘point-and-click’) task was performed. All mice were associated with similar wrist extension postures (p= 0.41) and carpal tunnel pressures (p= 0.48). Pressures were significantly greater during dragging and pointing tasks than when resting the hand (static posture) on the mouse (p= 0.003). The mean pressures during the dragging tasks were 28.8- 33.1 mmHg, ∼ 12 mmHg greater than the static postures. Pressures during the dragging task were higher than the pointing task (33.1 versus 28.0 mmHg), although the difference was borderline non-significant (p= 0.06). In many participants the carpal tunnel pressures measured during mouse use were greater than pressures known to alter nerve function and structure, indicating that jobs with long periods of intensive mouse use may be at an increased risk of median mononeuropathy. A recommendation is made to minimize wrist extension, minimize prolonged dragging tasks and frequently perform other tasks with the mousing hand.

Perceived Musculoskeletal Loading during use of a Force-Feedback Computer Mouse

With 30 to 80 percent of computer work involving the use of a pointing device, engineers are constantly exploring new and better interface designs. The introduction of a force-feedback mouse, which provides high fidelity tactile cues via force output, may represent such a long-awaited technological breakthrough. However, force may also be a risk factor for musculoskeletal disorders of the upper extremity, especially those associated with the use of computer input devices. For a point-and-click task, we hypothesize that both the performance and the self-reported task difficulty and comfort (i.e. pain and discomfort) improve with the application of an attractive basin force field (gravity sink like effect) around the target in comparison to a typical mouse with no force field. Fifteen adult subjects performed a point-and-click task 520 times with and without an attractive force basin around the target. The movements varied in direction and distance, and the order of presentation was randomized. Movement times were significantly shorter (p &lt; 0.0001) with the attractive force basin than without it. Perceived user discomfort and pain as measured through a questionnaire were also smaller with the attractive basin than with none. For the given task, the results suggest that the use of an attractive force-feedback basin may reduce the musculoskeletal loading during computer mouse use.

Wrist posture during computer pointing device use

Objective: This research examines individual differences in the wrist postures adopted during the use of two pointing devices (mouse and trackball). Design: A multiple case study of twelve participants was employed. Background: The use of pointing devices may lead to musculoskeletal discomfort and injury as a consequence of prolonged exposure to postures involving wrist extension and ulnar deviation. Methods: Wrist flexion/extension and radial/ulnar deviation was measured while twelve participants completed two standardised tasks involving horizontal and vertical cursor movements respectively. Results: Exposure to extreme ulnar deviation and wrist extension was observed in the use of computer mouse and trackball. The trackball involved decreased ulnar deviation and increased wrist extension, however considerable individual differences were observed. Conclusions: Some users may be placed at risk of injury by prolonged exposure to the use of such devices, while others may not. A trackball may reduce the exposure to extreme ulnar deviation, but in some cases, a trackball may increase exposure to extreme wrist extension.

Influence of mouse position on muscular activity in the neck, shoulder and arm in computer users

Anecdotal reports of shoulder and arm discomfort related to computer mouse use are common. The aim of this study of ten subjects was to examine the influence of mouse position, relative to the keyboard, on shoulder and arm muscular activity and working posture. Surface electromyography and the Rapid Upper Limb Assessment were used to determine the differences in muscle activity and posture during an editing task in each of three mouse positions. Significantly less anterior ( p=0.01) and middle ( p=0.03) deltoid electromyographic activity was demonstrated when the computer mouse was positioned adjacent to a keyboard without a numeric pad when compared to performance of an identical task with the mouse adjacent to a standard keyboard. Electromyographic activity in trapezius muscle did not differ between mouse positions. Working posture of right handed mouse users is improved by removal of the numeric keypad.

Computer mouse use and cumulative trauma disorders of the upper extremities.

The computer mouse is now present in virtually every office environment because of the recent adoption of the graphical user interface. However, Karlqvist et al. (1994) pointed out that there still remains a paucity of work on the musculoskeletal problems associated specifically with computer mouse use. Likewise, there have been no published data on the magnitude of upper extremity musculoskeletal disorders associated with computer mouse use. In order to ascertain this magnitude, claims data from the Liberty Mutual Group were reviewed for the years 1986 to 1993, inclusive. Count, total cost and average cost per claim for all claims associated with computer use and computer mouse use were determined for the years in question. It was concluded that although there are few claims related to computer mouse use, it appears to be a growing problem, and therefore, perhaps, deserves more research and intervention attention. However, the present magnitude is less than for other musculoskeletal disorders.