The weight of computer mouse affects the wrist motion and forearm muscle activity during fast operation speed task

Identification of physically demanding work tasks among cleaners: field study using electromyography

While chronic forearm pain is a common and debilitating condition among cleaners, the most physically demanding tasks remain unidentified. The present field study examines forearm muscle activity during 9 common cleaning tasks in a real working environment. Seven healthy cleaners participated in this study (age: 35.17 ± 9.62 yr; height: 168.17 ± 8.06 cm; weight: 77.14 ± 13.78 kg; experience: 5.60 ± 3.29 yr). Surface wireless electromyography (EMG) was recorded from 2 muscles on both sides of the upper limb, flexor carpi ulnaris (FCU), and extensor carpi radialis (ECR), and normalized to maximal voluntary isometric contractions (MVIC). Top-3 demanding high-force tasks (90th percentile EMG) were the rough floor, dirty rough floor, and office floor mopping for the FCU, and mopping high walls, ceiling mopping, and baize cleaning for the ECR. Top-3 static work tasks (10th percentile EMG) were mopping low walls, ceiling mopping, and dirty rough floors mopping for the FCU and mopping of high walls, low walls, and ceiling for the ECR. The study identified the forearm muscles' most physically demanding work tasks during cleaning tasks. The development of better working tools is recommended to avoid high-force overload as well as prolonged static overload of these muscles in cleaners.

A Design Contribution to Ergonomic PC Mice Development

Developing new manual computer pointing devices abiding to the requirements set out in ergonomic product design literature necessitates joining contributions from several areas, including the ergonomic guidelines applicable to hand tool design, human–system interaction, and certain user characteristics such as anthropometric data. Computer mice are hand tools enabling the interaction with the computer, for use by people from both sexes and practically all ages. Moreover, the PC mouse’s intensive usage is able to cause musculoskeletal disorders. This paper reports on a study aimed at developing new computer mouse shapes, reducing forearm pronation, and providing hand–palm holding, supported by a literature review and an adequate design methodology, starting from known shapes of commercial products, the traditional (horizontal) computer mouse, and the vertical computer mouse. In this regard, potential concepts were generated as solutions to the previously specified problem through a set of creative tasks based on the specifications. Four new shapes were proposed to be evaluated through an assessment matrix; as a result, two new PC mice geometries were designed and fully prototyped. This study also reports on selected results of usability and an electromyographic evaluation of the prototypes against three commercial PC mice (horizontal, slanted, and vertical) by a sample of 20 participants, supporting validation of the development process and the newly developed geometries, with emphasis on the slanted conical innovative shape.

The effect of computer mouse mass on target acquisition performance among action video gamers

Advances in human performance have shifted research attention from individuals towards understanding the effects that equipment can have on their performance. In esports, the effect of gaming peripherals on performance has only recently been explored. In this study, we investigated the effect of computer mouse mass on gaming skill. 72 video game players performed a target acquisition task, a pertinent composite skill in first-person shooter (FPS) video games, while using computer mice that varied only by their mass (50g, 60g, 90g & 100g). Results showed that participants were 4% faster and 9% more accurate with 50g, 60g, and 90g mice compared to the 100g mouse. They were also 34% more accurate and 14% more precise when using lower control-display gain and preferred lighter mice (50g and 60g) when performing the skill at a lower control-display gain. Taken together, using a lighter mouse at lower sensitivity may augment target acquisition performance among video gamers.

Dynamics of forearm muscle activity in slanted computer mice use

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.

Comparison of the effect of nocturnal use of commercial versus custom-made wrist orthoses, in addition to gliding exercises, in the function and symptoms of carpal tunnel syndrome: A pilot randomized trial

BACKGROUND

Conservative treatment for carpal tunnel syndrome (CTS) often includes wrist orthosis. However, there is no consensus on whether commercial or custom-made wrist orthosis is better for the treatment.

PURPOSE

To assess feasibility of a study comparing nocturnal use of commercial versus custom-made wrist orthosis in the treatment of mild/moderate CTS and estimate their potential effects on function and symptoms.

STUDY DESIGN

Randomized clinical trial.

METHODS

Twenty-four individuals with mild/moderate CTS were randomized to wear either a commercial orthosis (n = 12) or a custom-made orthosis (n = 12). Participants used the assigned orthosis at night for 45 days and performed gliding exercises at home/work. We collected data on access to eligible population and feasibility of protocol. Data on use of orthosis, performance of exercises, and symptoms were collected through a dairy filled by the participant. Outcomes were pain (using Numeric Pain Rating Scale), symptom severity and functional status (using Boston Questionnaire), pinch strength (by dynamometry), and electromyographic activity of forearm muscles (sampled during a reach-to-grasp task). Outcomes were measured before and after the intervention.

RESULTS

There were no loses to follow-up in either intervention group. After treatment, we found increased tripod pinch strength and better symptoms and function in both orthosis groups, with better outcomes for the custom-made orthosis, although the differences were not statistically significant.

CONCLUSIONS

The preliminary results showed a potential for better outcomes from the custom-made orthosis. We established that a larger study would be feasible and could be designed and conducted based on the estimates provided by this study.

TRIAL REGISTRATION

Brazilian Registry of Clinical Trials (ReBEC) - registration number: RBR-74rqnz.

A tentative efficiency index for pointing device use in computer aided design: A pilot study

BACKGROUND

Focusing on the efficiency aspect of computer pointing devices' usability, this paper reports on a novel and tentative empirically derived efficiency index for 3D CAD.

OBJECTIVE

Three commercially available computer pointing devices were compared: a standard horizontal computer mouse, a vertical device (supporting neutral pronation of the forearm) and a slanted device.

METHODS

Pilot structured observations of 10 subjects' activity were carried out to estimate the proportion of each unique computer mouse operation during CAD modelling with a 3D parametric software. Pointing, dragging and steering standardized tasks were implemented by software and performed by 20 users. Effectiveness and efficiency were calculated and discomfort, effort and ease of use were subjectively assessed.

RESULTS

The mean efficiency index value was lower for the vertical device. Assessments of discomfort, effort and ease of use also supported considering preference for the horizontal and slanted devices, providing limited internal validation.

CONCLUSION

Results suggest the tentative index may offer a valid means of ranking performance of alternative pointing devices regarding operation efficiency.

Electromyographic analysis of relevant muscle groups during completion of computer tasks using different computer mouse positions

BACKGROUND

We analyzed muscular activity for different computer mouse positions during the completion of a timed computer task and determined whether the different mouse positions could affect muscular activity, productivity and perceived fatigue.

METHODS

The subjects were nine healthy young men. Two mouse positions were studied: the distal position (DP), with the forearm rested on the desk; the proximal position (PP), with only the wrist rested on the desk. The subjects performed a 16-min task in each position. Surface electromyography data were recorded for the upper back and shoulder muscles. Work productivity and muscular activity were measured for each mouse position. A visual analog scale was used to assess subjective fatigue.

RESULTS

Muscular activity was higher in muscle (m.) deltoideus (posterior) for the DP, while it was significantly higher in m. inferior infraspinatus for the PP. The visual analog scale score was significantly higher and work productivity was lower in the PP.

CONCLUSIONS

We found that using a mouse in the DP rather than the PP leads to less activity of the external rotators, less perceived fatigue and more productivity. This suggests that the DP is preferable to the PP for computer work involving a mouse.

A biomechanical study of spherical grip

Use of the hand is vital in working life due to the grabbing and pinching it performs. Spherical grip is the most commonly used, due to similarity to the gripping of a computer mouse. Knowledge of its execution and the involved elements is essential. Analysis of this exertion with surface electromyography devices (to register muscular activity) and accelerometer devices (to register movement values ) can provide multiple variables. Six subjects performed ball gripping and registered real-time electromyography (thenar region, hypothenar region, first dorsal interosseous, flexors of the wrist, flexor carpi ulnaris and extensors of the wrist muscles) and accelerometer (thumb, index, middle, ring, pinky and palm) values. The obtained data was resampled "R software" and processed "Matlab Script" based on an automatic numerical sequence recognition program. Electromyography values were normalized on the basis of maximum voluntary contraction, whilst modular values were calculated for the acceleration vector. After processing and analysing the obtained data and signal, it was possible to identify five stages of movement in accordance with the module vector from the palm. The statistical analysis of the variables was descriptive: average and standard deviations. The outcome variables focus on the variations of the modules of the vector (between the maximum and minimum values of each module and phase) and the maximum values of the standardized electromyography of each muscle. Analysis of movement through accelerometer and electromyography variables can give us an insight into the operation of spherical grip. The protocol and treatment data can be used as a system to complement existing assessments in the hand.