Effects of Netbook and Tablet Usage Postures on the Development of Fatigue, Discomfort and Pain

The number of people using online tablets in public places has increased dramatically. Their postures are dominantly characterized by non-neutral and awkward positions that in the long term may lead to a higher risk of musculoskeletal disorders. The purpose of this study was to investigate the effects of tablet compared to laptop (i.e. netbook) usage postures on the development of fatigue, discomfort and pain. A total of 12 participants accomplished email typing tasks for 2 hours with four different usage configurations: 1) Netbook-on-table, 2) Netbook-on-lap, 3) Tablet-on-table, and 4) Tablet-on-lap. Changes in fatigue, discomfort, and pain were monitored based on pinch grip strength (tip pinch, key pinch, and palmar pinch), rating of perceived discomfort, and Phalen's & Reverse Phalen's tests, respectively. The results indicated that the effect of portable device placement was significant (p < 0.05), with varied effects across measurements. No effect of portable computer type was found. The interactive effect of portable computer type and placement was only significant for right tip pinch (p < 0.05). The findings of this study can hopefully be used to increase the awareness of tablet users about associated fatigue, discomfort and pain while using a tablet in public places that may lead to a higher risk of musculoskeletal disorders

Moving Away From the Traditional Desktop Computer Workstations: Identifying Opportunities to Improve Upper Extremity Biomechanics

Statement of Problem: Office computer workers have elevated risks of adverse health outcome such as musculoskeletal disorders (MSDs) associated with computer work. Although they now have many alternatives, these modern computer workstations and associated technologies require new guidelines and recommendations for proper practice. We see this as an opportunity to improve current and future computer workstation designs through an ergonomics approach by improving users’ upper extremity biomechanics while interacting with these modern technologies. Method: The dissertation first utilized a psychophysical protocol to compare users’ self-selected set ups for sitting and standing computer workstations. Users’ biomechanics and perceived comfort across different computer tasks for the two workstations are then compared. Subsequently, a hand mapping technique was developed to evaluate effects of computer pointing devices on users’ hand posture and associated forearm muscle effort using 3-D motion analysis and surface electromyography. To improve mobile device ergonomics, we investigated tablet users’ biomechanical load, comfort level and performance while performing swipe actions at different tablet locations. Results: Different selected computer workstation set ups were found for sitting and standing. Compared to sitting, users while standing kept workstation components closer to their sternum and adopted a more neutral shoulder posture while working. However, users had greater wrist extension and started reporting more low back discomfort after 45 minutes. While investigating different computer pointing devices, we found device affordance associated with significantly different hand posture and forearm muscle load. Devices that required less holding and were centrally placed associated with more neutral shoulder and hand postures, with significantly less forearm muscle load. For tablet interface, swipe locations closer to the palm had significantly smaller forearm muscle load and more neutral posture across wrist and thumb joints. Conclusion: Through empirical results described in the dissertation, we demonstrated how users’ upper extremity biomechanics can provide insights into the complex interactions between users and modern computer workstations, both as a whole and with specific components. For technology innovation, ergonomics concepts and methodologies can be used to design future generation technologies that fit users’ physical capabilities to reduce MSDs risk while promoting performance

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

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

MUSCULOSKELETAL SYMPTOMS AND LAPTOP COMPUTER USE AMONG COLLEGE STUDENTS

Laptop computers are widely used by college students for academic and leisure activities (Cortes, Hollis, Amick, & Katz, 2002). However, there is limited research that identifies risk factors for musculoskeletal discomfort during laptop computer use in this population. This dissertation includes two studies: Study 1: This survey study explores characteristics of laptop computer use and relationships between laptop-related risk factors and discomfort; Study 2: This randomized cross-over study examines the effects of three most common laptop workstation setups on upper body postures, discomfort, and task productivity.Thirty students were recruited from the University of Pittsburgh. The survey was a self-administered questionnaire. Subjects¡¯ posture were videotaped while typing for 10 minutes in six laptop workstation setups (desktop sitting, chair sitting, lying prone, lying supine, floor sitting, and lap sitting), and the three most common workstation setups were analyzed. Body angles were digitized at 10-time points and averaged using ImageJ. Typing style was identified using the Keyboard-Personal Computer Style Instrument. Discomfort was determined using a 10-cm VAS. Task productivity was assessed by typing speed and accuracy. Data were analyzed by ANOVAs and Bonferroni post-hoc comparisons.Subjects were primarily female (83.3%), with a mean age of 26.0¡¾7.3, and white (63.3%). Survey results showed that the most common workstation setups were desktop sitting, followed by lying supine and chair sitting. There were no statistically significant relationships between laptop-related factors (duration and type of workstation setup) and discomfort. Most body angles were significantly different between the three workstation setups: neutral wrists and ulnar deviation, upright trunk, and greater shoulder flexion during desktop sitting; greater neck flexion, wrist extension, and ulnar deviation during chair sitting; less neck flexion and greater wrist flexion and trunk extension during lying supine. For typing style, subjects showed large differences in static postures among the workstation setups. Less discomfort and faster typing speed were observed during desktop sitting, followed by lying supine, and then chair sitting. Overall more neutral postures and less discomfort were observed during desktop sitting, followed by lying supine and chair sitting. These findings highlight the importance of laptop workstation setup choice for preventing potential musculoskeletal problems

Development and Validation of the Self-report Ergonomic Assessment Tool (SEAT)

Despite considerable advances in the practice of office ergonomics, office workers are still suffering from musculoskeletal disorders (MSDs). These disorders, like carpal tunnel syndrome, can lead to high medical costs for employers and intense pain and discomfort for employees. The design of software office workers use could be a contributing factor to their risk of developing MSDs and a tool sensitive enough for evaluating ergonomic risks associated with the design of software is needed. Presented here are the results of a series of three studies focused on the development, improvement, and validation of a Self-report Ergonomic Assessment Tool (SEAT). The SEAT was found to comprise two important factors, stress and strain, and was found to be sufficiently consistent and sensitive to the exertions and postures related to office work. Data from two studies were used to validate stress components of the SEAT, e.g., postures, by using recorded videos and comparing participants’ responses on the SEAT to those of trained raters. Results showed that participants were unable to reliably self-report stressors. Data from one study was used to validate the strain components of the SEAT by comparing participants’ self-reported discomforts to muscle activity measured via surface electromyography and muscle oxygenation measured via near infrared spectroscopy. Participants’ self-reported discomfort did correlate with these physiological measures, however, important exceptions revealed opportunities for future development and testing of the SEAT

DEVELOPMENT OF A CUSTOMIZED ELECTRONIC REMINDER TO FACILITATE POWERED SEATING FUNCTION USAGE AND COMPLIANCE WITH CLINICAL RECOMMENDATIONS: DESIGN PROCESS AND CLINICAL EFFICACY

Compliance with clinical guidance on powered seating function (PSF) usage is very low among individuals who use electric powered wheelchairs (EPWs), leading to high risks for secondary complications, with potentially devastating health consequences, and drastically reduced quality of life. The purposes of this research project were to 1) develop a pervasive and persuasive reminder system, Virtual Seating Coach (VSC), to facilitate appropriate use of PSFs for health management following clinical recommendations; and 2) evaluate the efficacy of VSC on facilitating PSF usage and improving compliance with clinical recommendations. Survey studies, in-lab tests, and a pilot test study were conducted to ensure that users' feedback was incorporated in the development of the VSC. The research team gradually improved and refined the VSC in the development process. A randomized group study was conducted to evaluate the efficacy of the VSC. Participants used study EPWs equipped with the VSC for 8 weeks, including 2 weeks of baseline data collection and 6 weeks of intervention by receiving an educational program or the VSC in conjunction with the educational program. The educational program included providing educational materials in video, pamphlet, and flash cards formats, and recurrent meetings with a clinician once every two weeks to discuss PSF usage. Twenty six individuals participated in the study, and sixteen of them completed the study protocol. The study results showed that the intervention of the VSC in conjunction with the educational program increased the compliance rate around 40%, while the intervention of the educational program alone increased the compliance rate around 18% compared to the baseline period. Providing timely cues, accessible instructions and feedback were critical to facilitate a desired health behavior. Participants had large variability in the directions and strength of correlations between PSF usage and measures of quality of life (QoL). Gender, experience in EPW and PSF usage, and ambulatory ability may affect the relationships between PSF usage and QoL. More studies are needed to determine how to interpret the measures of QoL as outcome measurements for the effect of PSF usage

Automatic Posture Correction Utilizing Electrical Muscle Stimulation

Habitually poor posture can lead to repetitive strain injuries that lower an individual\u27s quality of life and productivity. Slouching over computer screens and smart phones, asymmetric weight distribution due to uneven leg loading, and improper loading posture are some of the common examples that lead to postural problems and health ramifications. To help cultivate good postural habits, researchers have proposed slouching, balance, and improper loading posture detection systems that alert users through traditional visual, auditory or vibro-tactile feedbacks when posture requires attention. However, such notifications are disruptive and can be easily ignored. We address these issues with a new physiological feedback system that uses sensors to detect these poor postures, and electrical muscle stimulation to automatically correct the poor posture. We compare our automatic approach against other alternative feedback systems and through different unique contexts. We find that our approach outperformed alternative traditional feedback systems by being faster and more accurate while delivering an equally comfortable user experience