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Observed finger behaviour during computer mouse use
Abstract
Two-button computer mouse users may exhibit sustained, static finger lifting behaviours to prevent inadvertent activations by avoiding finger pressure on the buttons, which leads to prolonged, static finger extensor muscle loading. One hundred graduate students were observed during normal computer work in a university computer facility to qualify and quantify the prevalence of lifted finger behaviours and extended finger postures, as well as wrist/forearm and grip behaviour, during specific mouse activities. The highest prevalences observed were 48% of the students lifted their middle finger during mouse drag activities, and 23% extended their middle finger while moving the mouse. In addition, 98% of the students rested their wrist and forearm (77%) or wrist only (21%) on the workstation surface, and 97% had an extended wrist posture (15 degrees -30 degrees ) when using the mouse. Potential applications of these findings include future computer input device designs to reduce finger lifting behaviour and exposures to risk factors of hand/forearm musculoskeletal pain.
... Common tasks such as pointing, clicking and dragging with an input device require repetitive movements which can cause wrist/hand musculoskeletal disorders among computer users.[1] Studies have indicated that mouse use for more than 20 h/week may result in hand/wrist symptoms and more than 30 h/week may lead to carpal tunnel syndrome (CTS).[1] In order to solve this problem, a number of mouse manufacturers have been trying to design and produce ergonomic mice to reduce the risk of musculoskeletal injuries. Regardin ...
... Common tasks such as pointing, clicking and dragging with an input device require repetitive movements which can cause wrist/hand musculoskeletal disorders among computer users.[1] Studies have indicated that mouse use for more than 20 h/week may result in hand/wrist symptoms and more than 30 h/week may lead to carpal tunnel syndrome (CTS).[1] In order to solve this problem, a number of mouse manufacturers have been trying to design and produce ergonomic mice to reduce the risk of musculoskeletal injuries. Regarding this, some changes have been taken into account in the structure and complex interaction between designs and upper limbs. Unfortunately, ergonomic mouse designs h ...
... To evaluate the comfort of using each device, the participants were asked to carry out a 15-min standard task of dragging shapes in a table using the device. After completing the task, the levels of clicking, hand/wrist posture and overall comforts were evaluated on 10-point visual analog scales [1][2][3][4][5][6][7][8][9][10]15] in which lower scores indicated higher levels of comfort. ...
Background. This study was conducted to assess functional parameters and comfort of a new computer mouse (Ergomice) as compared with three other input devices. Materials and methods. Functional parameters (i.e., task completion time and error rate) of each device were assessed by 10 participants using standardized software based on Standard No. ISO 9241-9:2000. Comfort evaluation was also undertaken for each device using the visual analogue scale technique. Statistical analysis including the Wilcoxon signed-rank test and the Friedman test was performed using SPSS version 16. Results. The functional parameters of the standard mouse were better than those of the other devices. However, no significant difference was observed between this mouse and Ergomice. Overall comfort evaluation showed that the standard mouse and Ergomice were more comfortable to work with. The comfort level of hand/wrist posture in the Ergomice was higher than that of the other three devices. Conclusion. The design features of Ergomice could improve its functional properties. Hand/wrist posture comfort of Ergomice was judged to be high compared with that of the other devices.
... Research in physical therapy that has examined the effects of mouse use on wrist and arm pain in computer users has shown gender differences in hand and arm postures when performing movements with a mouse. A study on the finger postures of mouse users showed that men more frequently had a finger posture, in which the finger used for mouse clicking had a lifted finger posture where the middle portion of the finger was not in contact with the mouse [22]. Male participants in this study were also more likely to show an extended finger posture with a flexion angle of less than 15 degrees when gripping the mouse (refer to Figure 2 for an illustration of relevant movement terms). ...
... Some additional metrics were calculated, because prior empirical research would imply gender differences are possible for these mouse metrics even if they were N. Van Balen, H, Wang, C. Ball not reported in the actual studies. For example, males and females differ in their grip postures of the mouse and positioning of the finger over the mouse button [18,22,41], implying that gender differences could exist for metrics influenced by these grip postures. ...
Gender is one of the essential characteristics of personal identity that is often misused by online impostors for malicious purposes. This paper proposes a naturalistic approach for identity protection with a specific focus on using mouse biometrics to ensure accurate gender identification. Our underpinning rationale lies in the fact that men and women differ in their natural aiming movements of a hand held object in two-dimensional space due to anthropometric, biomechanical, and perceptual-motor control differences between the genders. Although some research has been done on classifying user by gender using biometrics, to the best of our knowledge, no research has provided a comprehensive list of which metrics (features) of movements are actually relevant to gender classification, or method by which these metrics may be chosen. This can lead to researchers making unguided decisions on which metrics to extract from the data, doing so for convenience or personal preference. Making choices this way can lead to negatively affecting the accuracy of the model by the inclusion of metrics with little relevance to the problem, and excluding metrics of high relevance. In this paper, we outline a method for choosing metrics based on empirical evidence of natural differences in the genders, and make recommendations on the choice of metrics. The efficacy of our method is then tested through the use of a logistic regression model.
... Research in physical therapy that has examined the effects of mouse use on wrist and arm pain in computer users has shown gender differences in hand and arm postures when performing movements with a mouse. A study on the finger postures of mouse users showed that men more frequently had a finger posture, in which the finger used for mouse clicking had a lifted finger posture where the middle portion of the finger was not in contact with the mouse [18]. Male partici-pants in this study were also more likely to show an extended finger posture with a flexion angle of less than 15 degrees when gripping the mouse (refer to Figure 2 for an illustration of relevant movement terms). ...
... Some additional metrics were calculated, because prior empirical research would imply gender differences are possible for these mouse metrics even if they were not reported in the actual studies. For example, males and females differ in their grip postures of the mouse and positioning of the finger over the mouse button [16,18,32], implying that gender differences could exist for metrics influenced by these grip postures. ...
Gender is one of the essential characteristics of personal identity but is often misused by online impostors for malicious purposes. However, men and women differ in their natural aiming movements of a hand held object in two-dimensional space due to anthropometric, biomechanical, and perceptual-motor control differences between the genders. Exploiting these natural gender differences, this paper proposes a naturalistic approach for gender classification based on mouse biometrics. Although some previous research has been done on gender classification using behavioral biometrics, most of them focuses on keystroke dynamics and, more importantly, none of them provides a comprehensive guideline for which metrics (features) of movements are actually relevant to gender classification. In this paper, we present a method for choosing metrics based on empirical evidence of natural difference in the genders. In particular, we develop a novel gender classification model and evaluate the model’s accuracy based on the data collected from a group of 94 users. Temporal, spatial, and accuracy metrics are recorded from kinematic and spatial analyses of 256 mouse movements performed by each user. A mouse signature for each user is created using least-squares regression weights determined by the influence movement target parameters (size of the target, horizontal and vertical distances moved). The efficacy of our model is validated through the use of binary logistic regressions.
... Research in physical therapy that has examined the effects of mouse use on wrist and arm pain in computer users has shown gender differences in hand and arm postures when performing movements with a mouse. A study on the finger postures of mouse users showed that men more frequently had a finger posture, in which the finger used for mouse clicking had a lifted finger posture where the middle portion of the finger was not in contact with the mouse [18]. Male participants in this study were also more likely to show an extended finger posture with a flexion angle of less than 15 degrees when gripping the mouse (refer to Figure 2 for an illustration of relevant movement terms). ...
... Some additional metrics were calculated, because prior empirical research would imply gender differences are possible for these mouse metrics even if they were not reported in the actual studies. For example, males and females differ in their grip postures of the mouse and positioning of the finger over the mouse button [16,18,31], implying that gender differences could exist for metrics influenced by these grip postures. ...
Traditional user authentication methods using passcode or finger movement on smartphones are vulnerable to shoulder surfing attack, smudge attack, and keylogger attack. These attacks are able to infer a passcode based on the information collection of user’s finger movement or tapping input. As an alternative user authentication approach, eye tracking can reduce the risk of suffering those attacks effectively because no hand input is required. However, most existing eye tracking techniques are designed for large screen devices. Many of them depend on special hardware like high resolution eye tracker and special process like calibration, which are not readily available for smartphone users. In this paper, we propose a new eye tracking method for user authentication on a smartphone. It utilizes the smartphone’s front camera to capture a user’s eye movement trajectories which are used as the input of user authentication. No special hardware or calibration process is needed. We develop a prototype and evaluate its effectiveness on an Android smartphone. We recruit a group of volunteers to participate in the user study. Our evaluation results show that the proposed eye tracking technique achieves very high accuracy in user authentication.
... Research indicated that these mice were not as efficient or usable as their counterparts. 4 In addition to this, ergonomic mice are not marketed to the average computer user. These concerns, coupled with a lack of innovation, mean that the average consumer has been purchasing the same basic mouse design for years. ...
... , a T-square on the wrist (7-10), a triangle on the lower arm(4)(5)(6), the elbow (3), the middle upper arm (2), and the shoulder (1). Markers were placed directly on the subject's skin or clothing with tape. ...
... In addition to the hand and wrist, it has been reported that computer users sustain a lifted finger posture over the mouse buttons during computer work, possibly to avoid inadvertent activations (Sogaard et al., 2001). A recent study was undertaken to quantify this behavior, and a prevalence of up to 48% of two-button computer mouse users was observed to demonstrate sustained lifted finger behaviors over the mouse buttons and extended hand and wrist postures during computer work (Lee et al., 2008). The middle finger had the highest prevalence of being lifted, and the lifted finger behavior was increased during dynamic periods of mouse use, such as moving the mouse or clicking a mouse button. ...
... Most of these studies, however, use instrumentation to quantify the postures and support of the upper extremity. Observational field studies, elicit information about normal human-computer interaction in representative environments, which cannot be gained from laboratory studies (Lee et al., 2008). ...
The purpose of this study was to test the inter-rater reliability of an observational instrument, the Mouse-Personal Computer Style instrument (M-PeCS), which assesses the stereotypical postures and movements of the upper body and upper extremity associated with computer mouse use. Two trained raters independently rated the video clips of 10 computer users completing three mouse tasks (pointing, steering, and dragging) for a total of 30 video clips to determine the inter-rater reliability. All but two items on the M-PeCS had good to excellent reliability (ICC=0.75 to 1.00). These results suggest that most items on the M-PeCS can be used to reliably document computer mouse use style between trained raters. Potential applications of this study include identifying and quantifying the exposure to postural risk factors that may contribute to hand and forearm musculoskeletal pain associated with intensive computer mouse use.
... It is considered that there are two main aiming techniques: aim flicking, which consists of quick and accurate shots from a neutral point to the target, and aim tracking, which refers to the aiming style where the crosshairs remain above the target [7]. In this sense, the mouse grip is an important factor in ergonomics, which can be categorized according to parameters like the degree of wrist extension, the fingers used for left and right clicking, the level of support of the wrist/forearm on the table, and the level of grip behavior [13]. Three of the most employed grip types among gamers are the palm grip, which is the most common, the claw grip, and the fingertip grip [14]. ...
The First-Person Shooter is a very popular genre in electronic sports (esports), where there are different aiming techniques such as Aim Flicking and Aim Tracking. Although the mouse grip is suggested as one of the most important factors in gaming performance, there is a lack of evidence on this topic. Therefore, the purpose of the present study was to determine the performances of three types of mouse grips (palm grip, claw grip, and fingertip grip) in two different tasks (flicking and tracking tasks) by analyzing kinematic and scoring variables. Twenty-two participants performed the tasks on a computer with the same monitor and mouse, each using their preferred grip: palm grip, claw grip, and fingertip grip. The aim400kg was used to perform the tasks, and a camera system (Optitrack’s Flex 3) was used to capture the mouse movement. The results from the flicking task indicated significant differences in the minimum cursor trajectory, with higher values observed in the claw grip compared to both the palm and fingertip grips. However, no significant differences were observed in the tracking task in terms of velocity, acceleration, or hand movement. Moreover, only high correlations were observed in the flicking task between Score and Reaction Time (r = −0.911) and between Score and Total Distance (r = 0.724). In conclusion, the mouse grip does not affect the Aim Flicking or Aim Tracking task performance. This study has revealed interesting results related to performance, including correlations between the Score, Reaction Time, and Total Distance in flicking tasks.
... When performing the aiming tasks, ECU and EDC produced 12.9% and 11.4% MVC, compared to 7.5% and 10.0% MVC when clicking alone. Prolonged mouse use has been strongly associated with musculoskeletal disorders (Gerr et al., 2004;Ijmker et al., 2007) due to sustained loading and non-neutral wrist postures (Burgess-Limerick et al., 1999;Jensen et al., 1998;Lee et al., 2008). The elevated muscle activity observed in the current study may therefore pose an increased risk of injury to gamers. ...
... [10][11][12] Previous studies have frequently reported a significant relationship between prolonged use of computer mouse and Musculoskeletal Disorders (MSDs). [13][14][15][16] Office workers with intensive mouse use usually experience more severe hand/wrist symptoms compared to those working without a computer mouse. 17 Specifically, Carpal Tunnel Syndrome (CTS) or median nerve compression is a common condition among office works with prolonged use of the mouse. ...
Background: Musculoskeletal disorders in the upper extremities
are common among computer users. This study aimed to assess
the effect of mouse pad angle on forearm muscles activity
and upper limb discomfort.
Methods: This is an experimental research design. The mouse
pad was set at 0, 10, 20, and 30 degrees of forearm supination.
Ten subjects performed an identical text editing task with a mouse
in each pad position. The electrical activity of the selected forearm
muscles was recorded with surface electrodes. 10-point rating
scales were used for assessing perceived discomfort.
Results: Extensor Carpi Radialis had the lowest mean of
Electromyography (EMG) values in the 0° slanted pad (5.94),
and the highest values were associated with Pronator Quadratus
in 0-degree slanted pad (22.29). The highest and the lowest mean
(SD) of the users’ upper limb discomfort were 3.70 (1.63) and 1.90
(1.28) in 30° and 10° slanted pads, respectively.
Conclusion: Using slanted mouse pads could be helpful and
practical tool for office workers to keep more neutral wrist/hand
positions.
... When investigating whether fingertip pressure can be used as a musculoskeletal risk identification reference Indicators, the pressure values under the data for the dragging task are more advantageous. In addition, the data analysis of the right mouse button may contain errors due to users' varying habits; for instance, some users lifted their middle fingers when using the mouse (Lee et al., 2008). As a result, the pressure of the right mouse button could not be collected, and we did not collect and analyze the pressure of the right mouse button's fingertip. ...
Over time, repeated mouse-dragging manipulation may cause discomfort in the upper extremities. This study compared biomechanical parameters, mouse movement data, and the discomfort perception index between 2-min mouse dragging and moving manipulation tasks with higher or normal target objectives. We recruited 20 non-symptomatic graphic design students who frequently engage in intensive mouse-dragging manipulation. We assessed the impact of continued dragging versus non-dragging manipulation using electromyographic data, mouse fingertip pressure data, and mouse trajectory velocity data. We also performed a temporal correlation analysis between EMG, mouse velocity, and fingertip pressure to investigate the relationship between physiological data and mouse movement performance. The study revealed significant differences between the dragging and moving tasks regarding muscle activity, mouse velocity, and fingertip pressure. In particular, the percentage of muscle activation on the right side of the extensor carpi radialis lon-gus (ECR) and the lateral head of the triceps brachii (TB) differed significantly between the two tasks, with higher muscle activation levels during the dragging task. Moreover, the average muscle activation of ECR and TB was significantly higher at high target operation levels. In addition, the study revealed that the horizontal, vertical, and mean mouse velocities were significantly higher for the dragging manipulation in the high target task than for the mouse moving manipulation. In the temporal correlation analysis, the correlation coefficients of muscle activation, fingertip pressure , and mouse mean velocity differed between the two mouse manipulation behaviors, with a higher correlation between muscle activation levels and pressure values during the dragging manipulation. KEYWORDS Mouse behavior characteristics; upper limb discomfort of WMSD; electromyography
... When investigating whether fingertip pressure can be used as a musculoskeletal risk identification reference Indicators, the pressure values under the data for the dragging task are more advantageous. In addition, the data analysis of the right mouse button may contain errors due to users' varying habits; for instance, some users lifted their middle fingers when using the mouse (Lee et al., 2008). As a result, the pressure of the right mouse button could not be collected, and we did not collect and analyze the pressure of the right mouse button's fingertip. ...
... Lee et al. [87] found 98% of students rested their wrists and forearms on the workstation when using the mouse above REH. The authors noted no chair armrests were available and that "features influencing the use of forearm supports needs to be further examined in future research" (p112). ...
BACKGROUND: Musculoskeletal disorders (MSDs) can be prevented by avoiding trauma caused by poor posture, compression, force, and repetition. Neutral postures are recommended to avoid MSDs.
OBJECTIVE: This study introduces Mouse With Your Arm™ (MWYA) methodology which promotes sitting back in a chair, using the chair’s armrest for forearm support at relaxed elbow height, matching surface and armrest height, and keeping the mouse on the surface edge. This position allows optimal task chair use, facilitates movement and neutral postures, avoids compression and contact stress, and is effective in mitigating MSDs.
METHOD: MWYA was applied and measured in the field for more 23 years providing over 3,500 individualized assessments to integrate a participant’s unique characteristics, reported health concerns, tasks, tools, and environment to achieve and sustain whole-body neutral and comfortable working postures.
RESULTS: Previous research has consistently recommended use of forearm support by a desk, apparatus, or wrist rest, and resulted in non-neutral, static postures and measured health consequences. By using armrests for support, MWYA avoids the potential of MSDs as can be caused by these previously endorsed postures.
CONCLUSION: By applying the five MWYA principles, computer users comprehend neutral posture and put forth the effort essential to creating healthy human computer relationships.
... FMG was shown to be able to estimate finger movement status [22,33]; therefore, index finger pressing was included in the protocol to represent this fine finger action. Index finger pressing is another commonly-used action in daily activities such as mouse clicking [50]. Index finger tapping was selected as the dynamic version of the finger pressing action. ...
Force myography (FMG) is an emerging method to register muscle activity of a limb using force sensors for human–machine interface and movement monitoring applications. Despite its newly gained popularity among researchers, many of its fundamental characteristics remain to be investigated. The aim of this study is to identify the minimum sampling frequency needed for recording upper-limb FMG signals without sacrificing signal integrity. Twelve healthy volunteers participated in an experiment in which they were instructed to perform rapid hand actions with FMG signals being recorded from the wrist and the bulk region of the forearm. The FMG signals were sampled at 1 kHz with a 16-bit resolution data acquisition device. We downsampled the signals with frequencies ranging from 1 Hz to 500 Hz to examine the discrepancies between the original signals and the downsampled ones. Based on the results, we suggest that FMG signals from the forearm and wrist should be collected with minimum sampling frequencies of 54 Hz and 58 Hz for deciphering isometric actions, and 70 Hz and 84 Hz for deciphering dynamic actions. This fundamental work provides insight into minimum requirements for sampling FMG signals such that the data content of such signals is not compromised.
... Sutter and Ziefle (2004; proposed the differences between the work efficiency of human-machine interactions using the technical characteristics between the change of feelings and the hardware (the change of hand movements and cursor movements). Lee et al. (2008) proposed a method to reduce the resulting musculoskeletal sensation of pain from finger gestures when using micelike input devices. Herring et al. (2011) proposed the modification of equipment shapes and dimensions, such as good handle design and easy-to-use control mechanisms, to enhance the comfort, practicability, and accuracy of handheld tools. ...
A method was proposed in this study for assessing the interface operating efficiency of a remote control. The operating efficiency of a product interface can be determined by the proposed approach in which the related dimensions of human palms were measured. The reachable range (blue zone) and the most comfortable range (green zone) were investigated when a user used a single hand (right hand) to operate the remote controls. After that, new remote control designs were created based on the measurement results and the operating efficiency of commercially available remote controls were determined for comparison. The operating efficiency is determined by calculating the overall distance of finger movements when manipulating the buttons and the overall operation time was recorded. The subjects who joined the body measurements and performed the experiments are right-hander Asian college students between the ages of 22 and 28. After further optimization, the reachable range became more average during one-handed operations and those frequently used keys were included into the comfortable range. The resulting operating efficiency performance is higher than commercially available products. The results serve as a good reference for detailed modifications of the products or for the decision making of design proposals.
... Finger bending has been generally used as a common gesture for sliding, scrolling, and scaling UI. People bend their index fingers when they scroll the wheel for skimming through web pages or documents [40]. In previous research, bending involved pinching is also mapped to the slider mechanism as a level controller [41]. ...
As pervasive computing is widely available during daily activities, wearable input devices which promote an eyes-free interaction are needed for easy access and safety. We propose a textile wearable device which enables a multimodal sensing input for an eyes-free mobile interaction during daily activities. Although existing input devices possess multimodal sensing capabilities with a small form factor, they still suffer from deficiencies in compactness and softness due to the nature of embedded materials and components. For our prototype, we paint a conductive silicone rubber on a single layer of textile and stitch conductive threads. From a single layer of the textile, multimodal sensing (strain and pressure) values are extracted via voltage dividers. A regression analysis, multi-level thresholding and a temporal position tracking algorithm are applied to capture the different levels and modes of finger interactions to support the input taxonomy. We then demonstrate example applications with interaction design allowing users to control existing mobile, wearable, and digital devices. The evaluation results confirm that the prototype can achieve an accuracy of for demonstrating all input types, for locating the specific interaction areas for eyes-free interaction, and the robustness during daily activity related motions. Multitasking study reveals that our prototype promotes relatively fast response with low perceived workload comparing to existing eyes-free input.
... mouse control, while flexing and extending the fingers many hours a day, includes some risk of overusing our finger joints. Recently, this specific relation has drawn the attention of only a few researchers, focusing respectively on finger joint pain in teachers (Ding et al., 2011), finger behaviour and PC mice (Lee et al., 2008), finger joint coordination (van Zwieten et al., 2010), and micro-trauma (Hedrih et al., 2005). Given the fact that 1 % of our population is subjected to rheumatoid arthritis (Gabriel et al., 1999) and that 5-20 % of young adults develop osteoarthritis (Mansat et al., 2007) -both chronic illnesses primarily affecting small finger joints -surprisingly few studies appeared in this clearly education-related domain, in contrast to e.g. the world of performing arts (Boyette, 2005). ...
This study offers data on finger joint morphology, revealed by micro-anatomical observations, histological screening, and various high resolution imaging techniques in in-vitro anatomical specimens of small finger joints. Such data may help to understand the use of finger joints while handling PC mice, especially flexing and extending the fingers in e.g. moving a PC mouse scrolling wheel during educational and professional activities. Possible solutions after long standing finger problems are proposed.
... Today, the computer is one of the most influential products in living and occupational environment, so that 25% of users have interacted with it over than 50% of their work time [1]. Ever since 1984 they have most physical interaction with the computer mouse, among various computer input devices, between one to two third of time during their work [2]. It should be noted that the lack of accurate and ergonomic design of it can lead to serious injuries, especially for the long-term professional users of computer. ...
Some criteria for designing an ergonomic mouse for professional computer users via scenario-based design are presented in order to decrease Work-Related Musculoskeletal Disorders (WMSDs) especially in upper limbs. Library research studies performed based on 5W-H approach extremely tend to medical, ergonomics and functional affairs. Since this study was user-centered design (interaction design), practical research studies performed for better comprehension of users needs by making use of questionnaire, interview and observation procedures in three field of design: ergonomics, functional and aesthetics. First, target group divided into three categories by using AHP method: A-users who work professionally with design, graphic and animation softwares; B-users who work professionally or unprofessionally with other softwares; and C-users who work professionally with engineering softwares. Then, 56 questionnaires are presented to this group and also they interviewed and 15 ones observed during interaction with computer mouse. Finally, 23 design criteria achieved and final idea designed based on these criteria. The most important notes that considered in final design are neutral position of wrist, ulnar deviation prevention and preventing from static and powerful grips.
... The left button (operated by the index finger) is the most commonly used while the right (operated by the middle finger) is used more sporadic. The hand position, normally applied, is in this paper referred to as the normal position (NP) and is shown in figure 1. Lee et al. (2007) recently have reported that 48 percent of a graduate student population lifted their middle finger not to do an unintentional right click during mouse use. Own unpublished observations indicate that this behaviour is most pronounced when doing left clicks. ...
This paper describes an evaluation of an alternative way to use an ordinary computer mouse. The function of the two mouse buttons were switched and the index finger operated the right button for normal clicking while the middle finger rested on the table directly to the right of the mouse. An electromyographic /EMG) evaluation of this alternative hand position in 29 subjects showed that the EMG activity in the extensor digitorum superficialis muscle was lower compared to a normal hand position both when the hand was resting on the mouse as well as during repeated clicking. All subjects showed a lower average EMG level during repeated clicking and 27 subjects reduced their activity when resting the hand on the mouse compared to a normal hand position on the mouse. 1 Introduction The use of computers in almost any human activity is constantly increasing in the industrialized world. According to Swedish statistics, 48 percent of the female population used a computer every day in 2003 while this figure had increased to 60 percent in 2006. Similar figures for men were 58 and 69 percent respectively (SCB, 2006).
... (Computer arm syndrome is a musculoskeletal disorder that typically manifests as pain in the upper extremities and the posterior region of the neck). The side of the upper extremity used to operate the mouse [8,[21][22][23][24], differences in mouse positions [25,26], differences in the shape of the mouse [20,[27][28][29], the speed of mouse use in detailed operations [30], and differences caused by the use of armrests [29] can all contribute to CRDs that arise from the use of a mouse. However, these previous investigations of mouse-based activities have primarily focused on the association between operating a computer and musculoskeletal disorders and many of them have examined the relationship between muscular activity and task-induced stress based on electromyography data. ...
Objectives:
This study investigated the association between task-induced stress and fatigue by examining the cardiovascular responses of subjects using different mouse positions while operating a computer under time constraints.
Material and methods:
The study was participated by 16 young, healthy men and examined the use of optical mouse devices affixed to laptop computers. Two mouse positions were investigated: (1) the distal position (DP), in which the subjects place their forearms on the desk accompanied by the abduction and flexion of their shoulder joints, and (2) the proximal position (PP), in which the subjects place only their wrists on the desk without using an armrest. The subjects continued each task for 16 min. We assessed differences in several characteristics according to mouse position, including expired gas values, autonomic nerve activities (based on cardiorespiratory responses), operating efficiencies (based on word counts), and fatigue levels (based on the visual analog scale - VAS).
Results:
Oxygen consumption (VO(2)), the ratio of inspiration time to respiration time (T(i)/T(total)), respiratory rate (RR), minute ventilation (VE), and the ratio of expiration to inspiration (Te/T(i)) were significantly lower when the participants were performing the task in the DP than those obtained in the PP. Tidal volume (VT), carbon dioxide output rates (VCO(2)/VE), and oxygen extraction fractions (VO(2)/VE) were significantly higher for the DP than they were for the PP. No significant difference in VAS was observed between the positions; however, as the task progressed, autonomic nerve activities were lower and operating efficiencies were significantly higher for the DP than they were for the PP.
Conclusions:
Our results suggest that the DP has fewer effects on cardiorespiratory functions, causes lower levels of sympathetic nerve activity and mental stress, and produces a higher total workload than the PP. This suggests that the DP is preferable to the PP when operating a computer.
... mouse control, while flexing and extending the fingers many hours a day, includes some risk of overusing our finger joints. Recently, this specific relation has drawn the attention of only a few researchers, focusing respectively on finger joint pain in teachers (Ding et al., 2011), finger behaviour and PC mice (Lee et al., 2008), finger joint coordination (van Zwieten et al., 2010), and micro-trauma (Hedrih et al., 2005). Given the fact that 1 % of our population is subjected to rheumatoid arthritis (Gabriel et al., 1999) and that 5-20 % of young adults develop osteoarthritis (Mansat et al., 2007) -both chronic illnesses primarily affecting small finger joints -surprisingly few studies appeared in this clearly education-related domain, in contrast to e.g. the world of performing arts (Boyette, 2005). ...
This study offers data on finger joint morphology, revealed by micro-anatomical observations, histological screening, and various high resolution imaging techniques in in-vitro anatomical specimens of small finger joints. Such data may help to understand the use of finger joints while handling PC mice, especially flexing and extending the fingers in e.g., moving a PC mouse scrolling wheel during educational and professional activities. Possible solutions after long standing finger problems are proposed.
European Society for the Systemic Innovation of Education (ESSIE) - Annual Assembly 2011, 27 May, Leuven (BE)
... Apart from practising a musical instrument, finger scrolling while handling a computer mouse also requires such finger stability. Recent studies dedicated to mouse scrolling kinematics have underlined the importance of good muscular balances, for finger stability, as well as during finger mobility 25,27) . ...
Computer simulation of normal goal-oriented motion of human lower arm and hand may be also successfully applied in studying movement disorders, known as focal dystonias. Upper limb focal dystonia includes disturbed muscle tension balances, leading to painful, impaired and often aberrant motions. In their attempts to trace the backgrounds of this disorder, several authors have stressed the importance of the brain primary somatosensory cortex, and its role in brain-mapping. This turns out to be especially relevant during learning processes of new motor skills like practising by musicians. The present overview however will mainly analyse musculoskeletal mechanisms of arm and hand movements, with regard to their kinematics in repetitive motions. We will concentrate on pronation and supination movements of the lower arm during repeated shifting of the hand, as in handling a computer mouse, and focus on the maintaining of stable finger position during PC mouse scrolling. Physical therapy (PT) already proved itself useful in treating these focal dystonias, also known as repetitive strain injury (RSI). As an adjuvant to PT, we wish to propose local vibration therapies. Encouraging results of such a treatment, emanating from a recent pilot-study, are presented in conclusion.
... As finger movement studies related tot PC use mainly concentrate on the second joint of the finger, known as the proximal interphalangeal (PIP-) joint, this study deals with mobility and stability of this PIP-joint in e.g. handling the PC mouse (5,6). Structures governing the PIP-joint's (and other finger-joints') stabile and coordinated movements were therefore observed by in vitro anatomical specimens, supple enough to simulate motion in vivo. ...
... As finger movement studies related tot PC use mainly concentrate on the second joint of the finger, known as the proximal interphalangeal (PIP-) joint, this study deals with mobility and stability of this PIP-joint in e.g. handling the PC mouse (5,6). Structures governing the PIP-joint's (and other finger-joints') stabile and coordinated movements were therefore observed by in vitro anatomical specimens, supple enough to simulate motion in vivo. ...
Highly intense use of the finger, while handling the computer mouse, as in e-learning, may lead to hand- or finger complaints, e.g. in the elderly. To understand the finger positions concerned, we analysed some of its joints by functional anatomical research.
A statically and dynamically stabilised finger arch is needed to prevent complaints.
... In addition, it appears that enough attention has not been paid to psychological aspects, consumers' interests and needs in the design and production of these mice 7 . Thus, users are forced to endure pain while working with a mouse 8 .This can cause increase in hand/wrist musculoskeletal disorders [9][10][11] . Although there are different types of ergonomic mice in the market, it seems that attention has been paid to new technologies and morphological characteristics, while their comfort, obligatory requirements, hand/wrist and arm postures and functional parameters have been neglected. ...
This study aimed to design a new mouse and evaluate some of its functional parameters. The prototype of an ergonomic mouse was made according to design principles.
The study was conducted from 2011 to 2013 in the Department of Ergonomics in Shiraz University of Medical Science. Functional parameters including Movement Time (MT) and error rate of the new mouse were evaluated by 10 participants based on ISO 9241-9 standard.
The application of design principles in the new mouse resulted in improving MT and error rate so that they could be comparable to those of a standard mouse. MT, in both the standard and the new mouse was 0.846 and 0.864 s, respectively. Error rate of the standard and the new mouse was reported as 13% and 19%, respectively. Statistical analysis showed no significant difference between the two mice from these perspectives.
Apparently, the studied functional parameters of the new mouse were similar to those of the standard one. The new mouse could be an appropriate substitution for the standard mouse without losing its positive characteristics.
... 7,8,[10][11][12] Several studies have suggested that the increased prevalence of upper-extremity symptoms may be associated with the overuse or misuse of a mouse. 5,7,[13][14][15] Armstrong et al 16 suggested possible pathways involved in the development of upper-extremity musculoskeletal disorders associated with mouse use. They described the cumulative nature of disorders caused by internal forces acting on body tissue (termed a dose) due to mouse use. ...
This study investigated the relationship between computer mouse work and contact pressure around the pisiform. Commonly performed mouse work was simulated using 3 different-shaped mice with 3 forearm positions. When typical mouse work was performed, the contact pressure on the pisiform area was evaluated using a digital pressure sensor and compared with that of the thenar area. Six mouse tasks were simulated. Results indicate that mouse users should avoid wrist-snap dragging and resting their wrist on the edge of the desk to minimize the pressure concentration on the pisiform area.
... Likewise in the case of mouse switch, the switch characteristics and finger posture on the mouse may have similar effect on the finger dynamics. Based on the statistical data reported by, most mouse users had neutral posture during mouse execution [5]. Sex, age and especially mouse activation force corresponded to the mouse click duration [6]. ...
In this paper, the biomechanics model of index finger flexion-extension during mouse click was formulated to analyze the force
applied on the mouse button change throughout the duration of mouse click. The biomechanics model was formulated by solving
nonlinear differential equations consisting of nonlinear mouse spring equation and Newton-Euler dynamic equation of three
links open-chain. The model was successfully solved. The fingertip force-time characteristics of index finger during switch
compression obtained from the mathematical model followed the similar trend as the fingertip force over time of keyboard switch.
Nevertheless, the duration of click based on such model is significantly less than the survey data. This may be due to the
fact that the model does not take the viscoelastic properties of fingertip pulp during switch compression into account. Moreover,
the result obtain from such model has not been successfully validated by the real experiment. Hence, the model validation
with the experiment on the force applied on the mouse switch during activation must be further investigated.
KeywordsMouse click-Mouse switch-Fingertip-Biomechanics-Nonlinear Spring
As the increasing usage scenarios of tablet computers led to more non-neutral postures, optimizing the touchscreen gesture input became imminent to improve system performance and users’ well-being. Therefore, we conducted a study to investigate the influence of four tablet configurations and seven touchscreen gestures on electromyography, performance, and subjective assessment. Our results indicated that muscular loads of shoulder decreased under the Stand-Hand configuration while it increased under the Sit-Table during gesture interaction. We also found that Drag-Up and Drag-Left tended to possess higher muscular loads of shoulder while Drag-Down caused greater muscular loads of index finger. Besides, two-touch gestures spent longer duration when performing long-distance movements. Dragging in the inner direction was supposed to be more efficient than that in the outer direction. Our findings could provide a scientific basis for guiding the appropriate selection and the use of touchscreen interaction in the future HCI field.
Students spend most of the quality hours of the entire day in a school environment. Therefore, their safety and security are priorities of school administration and teachers to keep them secure from injuries and other health issues. Students mostly rely on teachers for their daily academic activities within a classroom environment. Therefore, it is essential to find out teachers’ perceptions and awareness about ergonomics risk factors and their practices to reduce these factors for the safety of the children within the classroom environment. A qualitative case study was conducted in a private school of Pakistan, to investigate teachers’ perceptions about school ergonomics and their practices which directly or indirectly influence school ergonomics. Five school teachers of primary class 3 were interviewed through a self-developed semi-structured interview protocol. The result indicated that ergonomics is highly valued in school education for students’ safety and health. Teachers introduce appropriate physical exercise in the classroom to keep children healthy and active during school hours and provide postural awareness for developing proper body posture. Counselling parents on ergonomics risk factors was suggested, along with ergonomically designed furniture in the classroom and the use of light material backpacks are also recommended.
Introduction: For the past few years wrist pain has been related to repetitive movement of the hand, and the cases has been increasing dramatically. There are numerous factors that causes wrist pain especially occupational factors. Different population has been investigated regarding work-related wrist pain such as, factory workers, programmers, and even gamers. Up to now, there is no data baseline about the prevalence and risk factors of wrist pain among young adults. Objectives: To investigate the prevalence and risk factors of risk pain among young adults in University Tunku Abdul Rahman (UTAR) during Movement Control Disorder. Methods: Questionnaire was adapted from Patient Rated Wrist Evaluation Score (PRWE), Self-Developed Demographic Data was used to determine prevalence and potential risk factors for wrist pain on young adults in UTAR during Movement Control Disorder, by using convenient sampling method. Results: A total number of 144 participants had completed the questionnaire. Most of the participants were 20-25 years old. There are 100 female participants (69.4%) and 44 male participants (29.9%) who enrolled in this research. The prevalence of wrist pain among young adults in UTAR during Movement Control Disorder is relatively high according to PRWE score (71.53%) while according to self-modified questionnaire there are 33 participants who felt the pain at the wrist (22.92%). Conclusion: Repetitive movement of the wrist and poor ergonomics of the hand are the factors that cause of wrist pain among young adults in UTAR. Key words: Prevalence, risk factors, wrist pain, young adults, Movement Control Disorder.
Traditional gesture elicitation studies generally adopted the frequency ratio to select popular gestures among users. However, the chosen gestures were not always optimal and might pose a potential risk of musculoskeletal disorder under long-term use. The purpose of our research was to apply a novel assessment system combining the indices of electromyography (EMG), electrogoniometry, and subjective preference to the end-user elicitation experiment. In this study, we conducted a two-stage experiment to compare and analyze the results of the physiological and psychological measures for 33 candidate gestures of 16 given commands. Our results indicated that this assessment system could effectively determine the candidate gestures with lower physiological loads for all given commands except Maximize, and most of the selected gestures were in line with users’ mental models. Finally, we developed an optimal user-defined gesture set for the commands accommodated to human-computer interaction (HCI).
Background:
Static muscular activity of muscles activated in the use of the conventional PC mouse is believed to represent a higher risk for the musculoskeletal health of the user than dynamic muscular activity.
Objective:
This paper presents a compounded muscular activity dynamics indicator (akin to percent relative range), enabling comparison between computer handheld pointing devices.
Methods:
This muscular dynamism approach considers baseline muscular activity (APL, ECR, ECU and ED) relative to the Maximum Voluntary Contraction as well as the dynamics of muscular activation. The latter is computed as the ratio of the difference between APDF90 and APDF10 divided by APDF50 (APDF-Amplitude Probability Distribution Function for the 90th, 50th and 10th percentiles). The paper demonstrates the approach with results of comparative evaluation of a horizontal, a slanted and a vertical PC mouse, through surface EMG monitoring of 20 participants performing standardized graphical task with the devices.
Results:
Hand size impacts muscular activity dynamics in these four muscles, which supersedes differences in device geometry, across the range of devices tested.
Conclusion:
Smaller devices relative to hand size foster more dynamic muscular activity.
Among various types of home appliances, an electric steam iron has a higher risk since it needs to operate under a condition with a higher range of temperature. In this study, a group of college students were invited to operate an electric iron during the experiment in order to investigate the correlation between an operator's hand and the possible contact with the iron soleplate during usage. The purpose of this study was to determine the hand portions which could easily get burned and the portions of the iron soleplate which tend to cause injuries. The results of this study indicated that the hand portions which could easily touch the soleplate are the right-hand side of the thumb and the forefinger. On the other hand, the portions on the soleplate which tend to cause burns are on the left-hand side of the iron, especially the sharper and upper half. The results serve as a good reference for follow-up designers on an iron design based on the safety consideration.
Prevalence of static muscular activity is believed to represent a higher risk for musculoskeletal health than dynamic muscular activity. PC mouse usage is a kind of activity where static muscle activation levels, while low in general, can indicate potential for musculoskeletal disorders. The study reported in this paper proposes a forearm four muscle approach to evaluation of muscular activity during mouse use, describing the rationale for selection of the muscles monitored. Additionally, signal processing is also characterized in the paper. The paper also presents results of surface electromyography assessment of 20 participants interacting with a conventional type of PC mouse. Analysis of the electromyographic signals was performed via a procedure of Amplitude Probability Distribution Function (APDF) calculation for the 90th, 50th and 10th percentiles. Average APDF90 values of muscular activity as a percentage of Maximum Voluntary Contraction found were between 7% and 21%.
Smartphone operation currently follows the graphical user interface operation framework. Each of a product’s functions is executed by clicking or sliding the function icon. The graphical user interface is simple and easy to learn, and the vision-oriented operation was applicable to personal computers in the past. However, this design may not be suitable for multi-operational smartphones, for example, those that use in a dynamic operating environment. This study designs a method for using sliding operation on a touch screen in which a simple sliding operation is linked to multiple audio signals. With this design, the user can quickly activate the product’s functions using a sliding operation combined with audio signals without relying on vision. Thus, the diverse operational needs of smartphone users can be satisfied. With the foregoing discussion, the present study hopes to provide an improved and practical user interface for Taiwan’s mobile phone industry.
This paper presents a study which objective was to investigate the human interaction with the equipment of an office workstation
(mouse, keyboard, monitor, paper sheets, pens and calculator) during the activities of reading, writing, data entry and navigation
in a computer system for long periods of time and with ecological validation. A sample of 22800 observations, which corresponds
to 760 work-hours of 30 office workers, was classified into sixteen Interaction’s Categories (IC). The results show that the
participants read on the monitor more than on paper and they had a larger use of the mouse instead of the keyboard. Findings
of this study allow suggesting what graphical interface designers must seek for new strategies and solutions to reduce the
mouse need, exploring other peripherals as keyboard or voice recognition devices; or, at least, diminishing the amplitude
of movement with the mouse during the interaction with office’s software like the Microsoft® Office 2003.
KeywordsOffice workers product interaction–Ergonomics procedures–Observations methods–Video display terminal
Previous research has suggested that the mousing location that encourages the best posture cannot be used when the keyboard has a number pad, so researchers have suggested using keyboards without number pads. No previous researcher has tested whether users actually use the extra space available when they use keyboards without number pads. Participants were videotaped working at a computer workstation using a keyboard with a number pad in one round and using a keyboard without a number pad in the other round. The initial mouse placement locations were compared between the two rounds. The mouse was placed closer to the center of the workstation when the keyboard without a number pad was used (p < 0.001). These results suggest that a change in keyboard without any instruction or training is enough to encourage computer users to use the mouse closer to the sagittal plane, which in turn should encourage better posture. Keyboards without number pads should be used instead of standard, full-size keyboards.
Ever since the introduction of the personal computer, our daily lives are infl uenced
more and more by computers. A day in the life of a PhD-student illustrates this:
“At the breakfast table, I check my e-mail to see if the meeting later that day
has been confi rmed, and I check the time table of the train to Rotterdam. In the
train, I might check the latest news on my mobile phone with internet access
and from the moment I enter the offi ce to the moment I leave, 95% of the work
I perform involves computer work. I spend my day reading and writing articles,
searching information online, keeping in contact with fellow researchers and performing
data analyses. At the end of the afternoon, I check the computer data
fi les from study participants that have automatically been sent to us by means of
the university network. Back home, I buy tickets for a music festival online, and
stream the TV program I missed the night before from my laptop to the television.
While I’m lying in bed, I just send a quick message to a friend on MSN with my
laptop, and with that, another computer-fi lled day has ended.”
Th e rise of IT (information technology, which refers both to devices that
have digital technology built in and to software that is implemented in those
devices) has led to a massive change in the working process and working conditions
since the 1960’s. Th is impact has only been matched by the fi rst and second
industrial revolutions (Fourth European Working Conditions Survey 2005). A
large IT research company stated that during the summer of 2008, the number
of personal computers in use had surpassed 1 billion units, with the expectancy
of another billion unit increase already in 2014 (Gartner 2008).
Repetitive movements for computer users can result in complaints caused by extreme hand posture, finger movements, and force when using the computer, which is known as Work Related Upper Extremity Disorder (WRUED). This study is about the construction of electronic instrumentation for monitoring and quantifying these movements and forces, using sensors to register wrist posture and fingertip force with software developed to collect and process the data. Tests evaluated the performance of the instrumentation with seventeen subjects participating in this study. The maximum extension observed for the first test was 41°, however after training the subject decreased this value to 33°. Six subjects had a wrist extension of between 15° and 41° for the first test; five reduced their wrist extension (between 3° and 33°) during the second test (p = 0.08) while one subject increased instead of decreased it. No subject performed fingertip force greater than 0.77N during the first test; this was reduced to 0.57N during the second test (p = 0.04). The average typing frequency in the group decreased from 3.2Hz to 2.5Hz during the second test (p = 0.01). Results confirm that this solution may potentially contribute to hand movement reeducation, thereby reducing the risk of WRUED for computer users.
Nowadays the web map (E-map) is an indispensable wayfinding tool in the Internet-based society. However, its usability will vary with a different navigational technique or input device. The navigational techniques currently adopted by various web maps were investigated and analyzed. Moreover, two input devices, i.e., the mouse and the touch screen, were operated in four navigational techniques to study the differences in their functions and performances. Later, the research findings were utilized to develop a new navigational technique. The research was divided into two stages. During the first stage, all the navigational techniques in current use were investigated and compared. Then, based on the results of analysis, the enhanced navigator with continuous control (ENCC) was designed. During the second stage, the searching and browsing techniques of different web maps were simulated. Afterwards, the mouse and the touch screen were employed separately to conduct simulation tests in the following navigational techniques: (1) combined panning buttons (CPB), (2) distributed panning buttons (DPB), (3) ENCC, and (4) G&D. A total of 36 participants took part in the trials. At the end of the experiment, the operational performances of the participants were studied through the two-way analysis of variance (ANOVA); besides, the subjective evaluation questionnaires were answered. It was discovered that the mouse did better than the touch screen in the four navigational techniques. Besides, among the four techniques, ENCC showed the best performance. Capable of continuous control and continuous display, the ENCC interface was upgraded in terms of operational speed and directional control. The findings can be used as a reference in the design of web maps. Also, it is suggested that ENCC should be widely applied to touch screens and mice so that the navigation of information space may be facilitated.
The biomechanical benefits (e.g., muscular activity) of slanted ergonomic mice have been comprehensively identified; however, their effects on task performance and subjective responses have not been fully investigated. The present study examined the effects of two slanted mice (slant angle = 30° and 50°) in comparison with a conventional mouse (slant angle = 0°) in terms of task performance (task completion time and error rate) and subjective responses (perceived discomfort score and overall satisfaction score). Experimental results showed that all of the task and subjective measures worsened as the slant angle of the target mice increases. For example, the task completion time (unit: ms) and overall satisfaction score (unit: point) of the 30° slanted mouse (time = 0.71, satisfaction = -0.09) and 50° slanted mouse (time = 0.73, satisfaction = -0.79) significantly deteriorated than the conventional mouse (time = 0.65, satisfaction = 1.21). The slanted mice seem to compromise biomechanical benefits with task performance and subjective responses.
Recently, an interesting study was brought forward, concerning the distinguishing of our body from not-body devices 1 . In using the computer, the computer mouse may be regarded as such a device that is experienced as part of our body sometimes, especially in relation to hand and fingers. In handling the computer mouse however, hand and finger will always try to follow their own characteristic kinematics. It is not surprising therefore, that various upper extremity dysfunctions emerged, together with the increasing popularity of the PC. This coincidence may become even more relevant, also in view of the still growing computer use by e.g. the elderly 2 . In the next survey, some frequent hand and finger dysfunctions related to mouse scrolling will be dealt with, mainly based on our specific knowledge of finger anatomy and kinematics.
BACKGROUND: Students are faced with work demands requiring intense computer use throughout the week, often with cumulative hourly use per day exceeding that of adult workers. Extended daily computer use has been associated with a reported increase of musculoskeletal symptoms for college-aged students. New mouse designs offer alternative movement and postural strategies to potentially mitigate musculoskeletal stress for students.
OBJECTIVE: This study investigates the use of alternative computer mouse designs by college-aged students (18–25) through a precision task (point-and-click an on-screen target). Wrist movements, hand posture, and associated subjective user data were collected across innovative mouse designs to understand the physical impact and basic usability issues for this population.
PARTICIPANTS: Twenty-one (21) healthy, right handed students (11 female; 10 male) were enrolled in this study.
METHODS: Five mouse designs were assessed by investigating hand fit, wrist movements, and subjective accounts of ease of use, perceived control, comfort and aesthetics. Human performance was captured for each mouse design in terms of peak velocity, average movement time, and fastest movement direction using an electrogoniometer as participants performed the ISO 9241 multipoint standard Fitts' task using the Generalized Fitts' Law Model Builder software (GFLMB v.1.1C; [1]) within a zero-error setting (point-and-click task). Hand measurements were taken in both standardized anthropometric positions and adapted hand positions on five alternative mouse designs for a total of seven sets of measurements for each participant. Subjective data was collected through a series of questionnaires that were administered before, during, and after the mouse tasks.
RESULTS: Results for human performance, distal upper extremity posture (hand/wrist), and subjective data such as overall preference, ease of use, perceived control, and comfort are given for this population. Wrist extension exceeded 30 degrees for over 50% of the total movement time for 3 out of 5 mouse designs. Postural variations in hand molding of the metacarpophalangeal arch (MCP angle) across mouse design was shown to be related to mouse control and ease of use. Subjective evaluations showed no differences between males and females, and overall preference was correlated to subjective evaluations of comfort, ease of use, perceived control, and, to a lesser extent, product attractiveness.
CONCLUSIONS: Individual performance across the alternative mouse designs in this study showed overall faster movement speeds than the `conventional' mouse design, while exhibiting similar wrist posture behavior for extension and ulnar deviation. Wrist extension is a risk factor for musculoskeletal injuries such as carpal tunnel syndrome. The current ergonomic standard calls for wrist extension to be below 30 degrees, and 3 of the 5 mouse designs exceeded this value. Guidance and adherence to proper use techniques for alternative mouse designs for this population is warranted and will help mitigate potential musculoskeletal risks.
The primary goal of this research is to design “virtually multiple mouse wheels”. Virtually multiple wheels are defined as wheels that provide multiple manipulation positions for scrolling by the finger. A sensor senses the manipulation position of the finger, and issues a corresponding auxiliary signal, which allows the wheel to have multiple manipulation modes, that is, each of the manipulation positions is used as a separate virtual wheel. Through this design, a single mouse wheel can be turned into multiple mouse wheels, enhancing the operation efficiency of software functions.Several experiments are conducted to compare the time needed to operate software functions with the traditional combination of “mouse click + toolbar” and with the proposed “virtually multiple mouse wheels”. The results indicate that the design of virtually multiple mouse wheels can enhance the efficiency of operating software functions. Based on the experimental results, this concept is provided to assist designers a direction for devising extended applications of a single wheel.
The purpose of this research is introduce the design of an improved graphical user interface (GUI) and verifies the operational efficiency of the proposed interface. Until now, clicking the toolbar with the mouse is the usual way to operate software functions. In our research, we designed an improved graphical user interface - a tool ball that is operated by a mouse wheel to perform software functions. Several experiments are conducted to measure the time needed to operate certain software functions with the traditional combination of "mouse click + tool button" and the proposed integration of "mouse wheel + tool ball". The results indicate that the tool ball design can accelerate the speed of operating software functions, decrease the number of icons on the screen, and enlarge the applications of the mouse wheel.
In this article, we review past studies comparing randomized experiments to regression discontinuity designs, mostly finding similar results, but with significant exceptions. The latter might be due to potential confounds of study characteristics with assignment method or with failure to estimate the same parameter over methods. In this study, we correct the problems by randomly assigning 588 participants to be in a randomized experiment or a regression discontinuity design in which they are otherwise treated identically, comparing results estimating both the same and different parameters. Analysis includes parametric, semiparametric, and nonparametric methods of modeling nonlinearities. Results suggest that estimates from regression discontinuity designs approximate the results of randomized experiments reasonably well but also raise the issue of what constitutes agreement between the 2 estimates.
Integrative computer usage monitors have become widely used in epidemiologic studies to investigate the exposure-response relationship of computer-related musculoskeletal disorders. These software programs typically estimate the exposure duration of computer use by summing precisely recorded durations of input device activities and durations of inactivity periods shorter than a predetermined activity duration cutoff value, usually 30 or 60 sec. The goal of this study was to systematically compare the validity of a wide range of cutoff values. Computer use activity of 20 office workers was observed for 4 consecutive hours using both a video camera and a usage monitor. Video recordings from the camera were analyzed using specific observational criteria to determine computer use duration. This observed duration then served as the reference and was compared with 238 estimates of computer use duration calculated from the usage monitor data using activity duration cutoffs ranging from 3 to 240 sec in 1-sec increments. Estimates calculated with cutoffs ranging from 28 to 60 sec were highly correlated with the observed duration (Spearman's correlation 0.87 to 0.92) and had nearly ideal linear relationships with the observed duration (slopes and r-squares close to one, and intercepts close to zero). For the same range of cutoff values, when the observed and estimated durations were compared for dichotomous exposure classification across participants, minimal exposure misclassification was observed. It is concluded that activity duration cutoffs ranging from 28 to 60 sec provided unbiased estimates of computer use duration.
An experiment was conducted to investigate the effect of key stiffness on the development of fatigue, keyboard reaction forces, and muscle electromyography (EMG) responses. Six subjects typed continuously for 2 hours on each of two keyboards (0.28 N or 0.83 N resistance keys, presented in random order). Keyboard reaction force and root mean square finger flexor and extensor EMG were recorded for 2 minutes at 250 Hz for every 10 minutes subjects typed. After typing for 2 hours subjects were given a 2-hour rest break and then typed on the remaining keyboard for an additional 2 hours Fifty-four percent more peak force, 34% more peak finger flexor EMG, and 2% more peak finger extensor EMG were exerted while using the 0.83 N keyboard. Peak and 90th percentile values showed similar trends and were well correlated for force and finger flexor and extensor EMG. Subjects typed much harder than necessary (4.1 to 7.0 times harder on the 0.28 N keyboard and 2.2 to 3.5 times harder on the 0.83 N keyboard) to activate the keys. Fatigue was observed on the 0.83 N keyboard during 2 hours of continuous typing, but the trends were mild. It appears that the ratio of typing force to flexor EMG may not be a sensitive enough indicator of fatigue for low-force high repetition work.
The aim of this study was to compare the postural load during VDU work in the following work postures: (1) Supporting and not supporting the forearms on the table top, (2) Sitting and standing positions, and (3) Sightline to the centre of the screen at an angle of 15 degrees and 30 degrees below the horizontal. The muscle load from the upper part of musculus trapezius and from the lumbar part of musculus erector spinae (L3 level) was measured by electromyography (EMG). Postural angles of head, upper arm and back were measured by inclinometers. The load on m. trapezius when using the keyboard was significantly less in sitting with supported forearms compared to sitting and standing without forearm support. Further, the time and number of periods when the trapezius load was below 1% MVC was significantly greater with support versus no support. The load on the right erector spinae lumbalis was also significantly less and the time when the load was below 1% MVC was significantly longer in a sitting work position with support versus standing without support. In addition, when using a mouse supporting the forearms reduced the static trapezius load in sitting. The results from this study document clearly the importance of giving the operator the possibility of supporting the forearms on the table top.
This study assessed work postures, movements, psychosocial job demands, and shoulder and wrist extensor muscle activity and registered the prevalence of musculoskeletal symptoms of computer-aided design (CAD) operators.
A questionnaire survey was used to study the use of the computer mouse, psychosocial work factors, and musculoskeletal symptoms among 149 CAD operators. A workplace study was performed using observations, electrogoniometers on the wrists, and electromyography to measure exposures and physiological responses during CAD work among a subgroup of the CAD operators.
Musculoskeletal symptoms were far more prevalent for the arm or hand operating the mouse than for the other arm or hand, and women were more affected than men. The symptoms may be related to such risk factors as repetitive movements, static postures (eg, ulnar-deviated and extended wrist on the mouse side), and static muscular activation patterns. The risk factors were present due to continuous mouse use and possibly also due to high demands for mental attentiveness, precision, and information processing.
Exposure during work with a computer mouse may present a risk for developing musculoskeletal symptoms. Improvements should focus on introducing more variation.
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, approximately 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.
When a person produces isometric force with one, two, or three fingers, the other fingers of the hand also produce a certain force. Enslaving is the involuntary force production by fingers not explicitly involved in a force-production task. This study explored the enslaving effects (EE) in multi-finger tasks in which the contributions of the flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS), and intrinsic muscles (INT) were manipulated. A new experimental technique was developed that allows the redistribution of the muscle activity between the FDP, FDS, and INT muscles. In the experiment, ten subjects were instructed to perform maximal voluntary contractions with all possible one-, two-, three-, and four-finger combinations. The point of force application was changed in parallel for the index, middle, ring, and little fingers from the middle of the distal phalanx, to the distal interphalangeal joint, and then to the proximal interphalangeal joint. It was found that: (1) the EE of similar amplitude were present in various experimental conditions that involved different muscle groups for force production; (2) the EE were large on average--the slave fingers could produce forces reaching 67.5% of the maximal forces produced by themselves in a single-finger task; (3) the EE were larger for neighboring fingers; and (4) the EE were non-additive--in most cases, the EE from two or three fingers were smaller than the EE from at least one finger. EE among different muscles suggest a widespread neural interaction among the structures controlling flexor muscles in the hand as the main mechanism of finger enslaving.
To evaluate the effectiveness of arm and wrist supports in reducing the workload during computer work.
Female subjects (n=10) performed computer work in conditions with arm or wrist supports and in a condition without supports.
Sustained muscle tension in the trapezius muscle is a risk factor for trapezius myalgia. Arm and wrist supports are used at the workplace with the intention to reduce the muscle tension. The effectiveness of these aids in reducing the load is not clear.
A typing task and mouse task were performed, each with four types of supports and without support. Electromyography and subjective ratings were used to quantify the workload.
Lower levels of trapezius muscle activation were recorded with the use of arm supports. Wrist supports did not reduce activation. The rated perceived workload did not discriminate.
Reduction of muscle activation in the neck-shoulder region during standard visual display unit work can be achieved with arm supports. Wrist supports do not reduce the strain on the neck-shoulder region. Subjective ratings seem not of use in selecting ergonomic aids in low intensity tasks. RelevanceVisual display unit workers are at risk of developing complaints of the neck and upper extremity. Arm and wrist supports are introduced at the workplace to reduce the workload. If arm and wrist supports are effective in reducing the workload they might be of use as preventive measures to reduce the risk of neck-shoulder complaints.
The purpose of this study was to develop and validate a sampling strategy for characterizing the finger force exposures associated with computer mouse use.
Mouse forces were measured from 16 subjects (8 men, 8 women), on 3 separate days, at their actual workstations while they performed (i) their regular work, (ii) a battery of standardized tasks, and (iii) simulated mouse use.
The forces applied to the mouse did not vary between hours or days. During regular work, the mouse was used 78.0 (SD 40.7) times per hour, accounting for 23.7 (SD 9.5)% of the worktime. The mean forces applied to the sides and button of the mouse were low, averaging 0.6 % (0.35 N) and 0.8 % (0.43 N) of the maximal voluntary contraction, respectively. The forces applied to the mouse during the standardized tasks differed from the regular work forces; however, there were moderate-to-strong correlations between the 2 measures.
With respect to performing exposure assessment studies, the 3 major findings were (i) mouse force measurements should be made while subjects perform their actual work in order to characterize the absolute applied force accurately, (ii) the forces applied to the mouse during the performance of a short battery of standardized tasks can be used to characterize relative exposure and identify computer operators or work situations for which higher forces are applied to the mouse, and (iii) subjects cannot accurately simulate mouse forces.
The aim of this study was to examine relations between computer work aspects and elbow and wrist/hand pain conditions and disorders.
In a 1-year follow-up study among 6,943 technical assistants and machine technicians self-reported active mouse and keyboard time, ergonomic exposures and associations with elbow and wrist/hand pain were determined. Standardized clinical examinations were performed among symptomatic participants at baseline and at follow-up.
For continuous duration of mouse time adjusted linear effects were statistically significant for all investigated pain conditions. For continuous duration of keyboard time the corresponding effects were statistically significant for wrist/hand pain conditions except incident 'severe' wrist/hand pain. There were no threshold effects above 0 hr per week (hr/w) of mouse exposure in association with pain conditions, while keyboard exposure showed a threshold effect with 12-month wrist/hand pain at follow-up. Clinical diagnoses were not associated with exposure.
Detailed examination of self-reported exposures showed that mouse and keyboard time predicted elbow and wrist/hand pain from low exposure levels without a threshold effect, but mouse and keyboard time were not predictors of clinical conditions.
Most previous studies of the association between psychosocial stress and musculoskeletal illness among computer users have been cross-sectional and have yielded inconsistent results. The association between a measure of psychosocial stress, "job strain", and incident neck-shoulder and arm-hand musculoskeletal symptoms was investigated among recently hired computer users.
The participants worked for one of several large employers and were followed prospectively for 6 months. The "job demands" and "decision latitude" subscales of the Job Content Questionnaire were used to estimate the job-strain quadrants and a ratio measure of job strain which was subsequently categorized. Incident musculoskeletal symptoms were obtained with weekly diaries. Proportional hazards models were used to estimate associations between job strain and incident musculoskeletal symptoms.
Those in the high-strain quadrant were at increased risk of neck-shoulder symptoms [hazard ratio (HR) 1.65, 95% confidence interval (95% CI) 0.91-2.99] when compared with those in the low-strain quadrant. Those in the highest strain-ratio category were also at increased risk of neck-shoulder symptoms when compared with those in the lowest strain-ratio category (HR 1.52, 95% CI 0.88-2.62). Modification by previous years of computer use was observed, with an elevated risk observed for those in the highest job-strain ratio category who also had low previous computer use (HR 3.16, 95% CI 1.25-8.00). There did not appear to be an association between either measure of job strain and incident arm-hand symptoms.
In this cohort, workers who reported high job strain were more likely to develop neck-shoulder symptoms.
Call centre work with computers is associated with increased rates of upper body pain and musculoskeletal disorders.
This one year, randomised controlled intervention trial evaluated the effects of a wide forearm support surface and a trackball on upper body pain severity and incident musculoskeletal disorders among 182 call centre operators at a large healthcare company. Participants were randomised to receive (1) ergonomics training only, (2) training plus a trackball, (3) training plus a forearm support, or (4) training plus a trackball and forearm support. Outcome measures were weekly pain severity scores and diagnosis of incident musculoskeletal disorder in the upper extremities or the neck/shoulder region based on physical examination performed by a physician blinded to intervention. Analyses using Cox proportional hazard models and linear regression models adjusted for demographic factors, baseline pain levels, and psychosocial job factors.
Post-intervention, 63 participants were diagnosed with one or more incident musculoskeletal disorders. Hazard rate ratios showed a protective effect of the armboard for neck/shoulder disorders (HR = 0.49, 95% CI 0.24 to 0.97) after adjusting for baseline pain levels and demographic and psychosocial factors. The armboard also significantly reduced neck/shoulder pain (p = 0.01) and right upper extremity pain (p = 0.002) in comparison to the control group. A return-on-investment model predicted a full return of armboard and installation costs within 10.6 months.
Providing a large forearm support combined with ergonomic training is an effective intervention to prevent upper body musculoskeletal disorders and reduce upper body pain associated with computer work among call centre employees.
High static loading of the forearm extensor musculature has been observed during keying tasks. To reduce the level of loading, one must first understand the contributing factors. A simulation of the human finger was used to determine muscle force contributions during a static index finger key press at several wrist postures. The planar model included active and passive muscle forces of the intrinsic and extrinsic finger muscles. The model was expanded to include the passive forces from the other fingers as well as the weight of the hand to determine the exertion required of the wrist extensor muscles to maintain the given wrist and finger postures. Model results indicated that greater than 25% of maximal exertion is required of the wrist extensors when the wrist is extended to 30. The increased moment contribution from passive forces of the extrinsic finger flexor muscles was responsible for the majority of the increased wrist extensor contribution as the wrist was extended. These findings are in relative agreement with previous electromyographic studies and may indicate a mechanism for forearm extensor pain in office workers. Potential applications of this research include ergonomic modeling of the upper limb to determine internal loads that may lead to work-related disorders.
Aims
To determine the occurrence of pain conditions and disorders in the forearm and to evaluate risk factors for forearm pain in a cohort of computer workers.
Methods
A total of 6943 participants with a wide range of computer use and work tasks were studied. At baseline and at one year follow up participants completed a questionnaire. Participants with relevant forearm symptoms were offered a clinical examination. Symptom cases and clinical cases were defined on the basis of self reported pain score and palpation tenderness in the muscles of the forearm.
Results
The seven days prevalence of moderate to severe forearm pain was 4.3%. Sixteen of 296 symptom cases met criteria for being a clinical forearm case, and 12 had signs of potential nerve entrapment. One year incidence of reported symptom cases was 1.3%; no subjects developed new signs of nerve entrapment. Increased risk of new forearm pain was associated with use of a mouse device for more than 30 hours per week, and with keyboard use more than 15 hours per week. High job demands and time pressure at baseline were risk factors for onset of forearm pain; women had a twofold increased risk of developing forearm pain. Self reported ergonomic workplace factors at baseline did not predict future forearm pain.
Conclusion
Intensive use of a mouse device, and to a lesser extent keyboard usage, were the main risk factors for forearm pain. The occurrence of clinical disorders was low, suggesting that computer use is not commonly associated with any severe occupational hazard to the forearm.
This research examines individual differences in the wrist postures adopted during the use of two pointing devices (mouse and trackball).
A multiple case study of twelve participants was employed.
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.
Wrist flexion/extension and radial/ulnar deviation was measured while twelve participants completed two standardised tasks involving horizontal and vertical cursor movements respectively.
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.
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.
Self-report data on musculoskeletal discomfort were collected from several hundred VDT users in two agencies of a state government. Aspects of worker posture and workstation design were objectively assessed for 40 of the VDT users. Multiple regression analyses were used to examine the relationship between these ergonomic variables and musculoskeletal discomfort. Effects of ergonomic factors on musculoskeletal discomfort were clearly evident in the analyses. Regression models explained up to 38% of the variance in discomfort at different body sites. Of special interest was that leg discomfort increased with low, soft seat pans, suggesting that postural constraint is more important than thigh compression as a risk factor for leg discomfort in VDT work. In addition, arm discomfort increased with increases in keyboard height above elbow level, supporting arguments for low placement of the keyboard. Finally, high levels of neck and shoulder girdle discomfort observed in the study population suggest the need for further attention to the control of cervicobrachial pain syndromes in VDT work.
Work postures and movements of the upper limb were analysed for 12 'mouse' operators and 12 'non-mouse' computer operators employed in word-processing work. Measurements were carried out during correction of a given text. 'Mouse' operators spent 64% of the working time with the operative wrist deviating more than 15 degrees towards the ulnar side, while 'non-mouse' operators spent 96% of the time with the corresponding wrist in neutral position towards radial deviation. The rotation in the shoulder was at all times in neutral position towards inward rotation for 'non-mouse' operators, while 'mouse' operators worked 81% of the time with the shoulder rotated outward more than 30 degrees. 'Mouse' operators corrected a longer text during the given time. Our observations showed long periods of strenuous working postures for 'mouse' operators compared to 'non-mouse' operators. We believe that further investigations need to be carried out on the effects of word-processing techniques and to develop ergonomic work station designs for the 'mouse' and other non-keyboard input devices.
This study concerned the influence of 6 positions of the computer mouse on the work table on posture, muscular load, and perceived exertion during text editing.
An optoelectronic 3-dimensional motion analysis system was used to register the postures of 10 men and 10 women using video display units. Muscular load was also registered (with electromyography), as was perceived exertion (with rating scales).
A neutral posture with a relaxed and supported arm showed the least perceived exertion, and the electromyographic results showed low activity in both trapezius muscles in this position. Short operators (all women) showed a numerically higher activity in the 4 examined muscles than the tall operators (all men, except 1). This finding could be related to lower muscle force among women and to anthropometric differences, which also influence biomechanic load moments. Narrow-shouldered operators (8 women and 1 man) and short operators worked with larger outward rotation and abduction of the shoulder in a position of the mouse lateral to the keyboard than the broad-shouldered (7 men and 2 women) and tall operators did. Arm support markedly reduced muscle load in the neck-shoulder region among the operators.
The operators using video display units in this study preferred to use the mouse on a table in a close to relaxed, neutral posture of the arm in combination with arm support. Short and narrow-shouldered operators worked in more strenuous postures of the arm when the mouse was located lateral to the keyboard.
Motor unit (MU) activity pattern was examined in the right-hand extensor digitorum communis muscle (EDC) during standardised finger movements simulating actual computer mouse tasks. Intramuscular recordings were performed with a quadripolar needle electrode. Nine women performed four lifts of their right-hand index finger, middle finger or both as well as a number of double clicks. Additionally, the subjects performed contra lateral activity with their left-hand fingers and for three subjects recordings were also obtained during an interview with no physical activity. Besides the expected close coupling of MU activity with finger movement, activity was observed in three different situations with no physical requirements. Attention related activity was found before or after performance of the finger movement task, contra lateral activity in right EDC during left-hand finger tasks, and activity during mental activity without any finger movements involved. A relatively large number of doublet occurrences suggest they are a natural part of the activation pattern during performance of the rapid finger movement required to perform an efficient double click on the computer mouse.
The goal of this study was to determine the systematic effect that varying the slope angle of a computer keyboard along with varying keyboard height (relative to elbow height) have on wrist extension angle while typing. Thirty participants typed on a keyboard whose slope was adjusted to +15 degrees, +7.5 degrees, 0 degrees, -7.5 degrees, and -15 degrees. The height of the keyboard was set up such that participants' wrists were at the same height as their elbows, above their elbows, and four cm below their elbows. Results showed that as keyboard slope angle moved downward from +15 degrees to -15 degrees, mean wrist extension decreased approximately 13 degrees (22 degrees at +15 degrees slope to 9 degrees at -15 degrees slope). Keyboard height had a similar effect with mean wrist extension decreasing from 21.8 degrees when the keyboard was lower than elbow height, to 7.3 degrees when the keyboard was higher than elbow height. Potential application of this research includes the downward sloping of computer keyboards, which could possibly be beneficial in the prevention of musculoskeletal disorders affecting the wrist.
To determine the occurrence of pain conditions and disorders in the forearm and to evaluate risk factors for forearm pain in a cohort of computer workers.
A total of 6943 participants with a wide range of computer use and work tasks were studied. At baseline and at one year follow up participants completed a questionnaire. Participants with relevant forearm symptoms were offered a clinical examination. Symptom cases and clinical cases were defined on the basis of self reported pain score and palpation tenderness in the muscles of the forearm.
The seven days prevalence of moderate to severe forearm pain was 4.3%. Sixteen of 296 symptom cases met criteria for being a clinical forearm case, and 12 had signs of potential nerve entrapment. One year incidence of reported symptom cases was 1.3%; no subjects developed new signs of nerve entrapment. Increased risk of new forearm pain was associated with use of a mouse device for more than 30 hours per week, and with keyboard use more than 15 hours per week. High job demands and time pressure at baseline were risk factors for onset of forearm pain; women had a twofold increased risk of developing forearm pain. Self reported ergonomic workplace factors at baseline did not predict future forearm pain.
Intensive use of a mouse device, and to a lesser extent keyboard usage, were the main risk factors for forearm pain. The occurrence of clinical disorders was low, suggesting that computer use is not commonly associated with any severe occupational hazard to the forearm.
To examine the effects of postural and keyswitch characteristics on musculoskeletal tissue loading during tapping on computer keyswitches.
We hypothesized that joint torques, stiffness and work parameters differ across keyswitch designs and finger postures typical of those observed during computer keyboard typing. We experimentally measured joint kinematics and calculated joint torques while tapping on different keyswitches in different postures, and analyzed the data using mechanical impedance models.
Sixteen human subjects tapped with the index finger on computer keyswitches mounted on a sensor which measured vertical and horizontal forces. Miniature electro-optical goniometers mounted dorsally across each finger joint measured joint kinematics. Joint torques were calculated from endpoint forces and joint kinematics using an inverse dynamics algorithm. A linear spring-damper impedance model was fitted to joint torque, position, and velocity during the contact period of each tap. Subjects tapped in three postures approximating those employed during tapping on three rows of a computer keyboard, on four different keyswitches, resulting in 12 conditions.
More extended finger posture was associated with greater joint torques, energies, and stiffnesses, despite minimal differences in endpoint forces across posture. Greater keyswitch make forces were associated with increased forces, joint torques and joint stiffnesses, however this relationship was not monotonic.
Joint torques and stiffness parameters differed across keyswitch designs and finger postures. Estimates of joint impedance and work provided a unique perspective into finger dynamics.
Determining the causes of work-related musculoskeletal disorders is facilitated by characterizing workplace task biomechanics, which can be linked to specific injury mechanisms.
RULA (rapid upper limb assessment) is a survey method developed for use in ergonomics investigations of workplaces where work-related upper limb disorders are reported. This tool requires no special equipment in providing a quick assessment of the postures of the neck, trunk and upper limbs along with muscle function and the external loads experienced by the body. A coding system is used to generate an action list which indicates the level of intervention required to reduce the risks of injury due to physical loading on the operator. It is of particular assistance in fulfilling the assessment requirements of both the European Community Directive (90/270/EEC) on the minimum safety and health requirements for work with display screen equipment and the UK Guidelines on the prevention of work-related upper limb disorders.
Alternatives to reduce postural constraints have to be sought in order to reduce musculoskeletal complaints related to computer work. This study aimed at documenting the impact of using the mouse on the left side of a standard keyboard (with a right numeric keypad) on upper-extremity posture. A simulated computer task was performed by 27 subjects in a laboratory before and 1 month after ergonomics training. Shoulder flexion and abduction, as well as wrist extension were reduced with left-handed mouse use. Sixteen of the 27 subjects truly converted to using the mouse with the left hand. After a month of using the mouse with the left hand, the time required to perform the same task reduced, the perceived difficulty and discomfort improved, though the time to perform the task was still longer than when using the mouse with the right hand. For work involving both keyboard and mouse use, and without the need of the numeric keypad, it would probably be preferable to use a keyboard without the numeric keypad if the mouse is to be used on the right-hand side. If such keyboards are unavailable, an interesting alternative would be to use the mouse on the left side provided sufficient time is allowed to get accustomed to it.
Office ergonomics: motion analysis of computer mouse usage
- P W Johnson
- J Hewes
- J Dropkin
- D M Rempel
Johnson, P.W., Hewes, J., Dropkin, J., Rempel, D.M., 1993. Office ergonomics: motion analysis of computer mouse usage. In: Proceed-ings of the American Industrial Hygiene Conference & Exposition, New Orleans, Louisiana, pp. 12–13.