Daily computer usage correlated with undergraduate students' musculoskeletal symptoms

Investigation of grip strength, pain threshold, pain tolerance and function in smartphone users

PURPOSE/AIM OF THE STUDY

Few studies have demonstrated the effects of smartphone use on grip strength and upper extremity function. The present study was purposed to compare smartphone users' grip/lateral pinch strength, pain threshold/tolerance and upper limb function.

MATERIALS AND METHODS

A prospective cross-sectional study was conducted with 241 individuals. Participants were divided into three groups with the cut-off values of the Smartphone Addiction Scale (SAS). The Edinburgh Handedness Inventory (EHI) was used to determine the dominant side. Thumb pain threshold and tolerance were evaluated with the algometer. A hand dynamometer measured the grip and lateral pinch strength. Upper extremity functions were evaluated with the Shortened Disabilities of the Arm, Shoulder and Hand Questionnaire (Quick-DASH).

RESULTS

Handgrip strength of the dominant/non-dominant extremities and Quick-DASH scores were higher in low-level smartphone users (p < 0.05). There was no significant difference between the groups on lateral pinch strength and pain threshold/tolerance (p > 0.05). Smartphone usage significantly affected dominant and non-dominant hand grip strength (Standardized β1 = -0.15, β2 = -0.15, p < 0.05). In addition, the smartphone use level negatively affected dominant lateral pinch strength (Standardized β = -0.12, p = 0.05). On the other hand, smartphone use positively affected upper extremity function (Standardized β = 0.17, p < 0.05).

CONCLUSIONS

As smartphone addiction increases, standard handgrip strength and functionality decrease. Pain threshold/tolerance is not affected by smartphone use. Future studies should focus on fine motor skills to present a more comprehensive upper limb function evaluation.

Effects of anti-fatigue lenses on performance, muscle activity and subjective discomfort responses during a seated computer task

Anti-fatigue lenses (AFL) intend to provide health benefits in association with computer work. Their effects on visual and muscle discomfort mechanisms and task performance remain unclear. Twenty-three computer users (n = 12 males) underwent two 90-min computer sessions with AFL or placebo lenses. Eye strain, body discomfort, typing performance, upper trapezius (UT) activation amplitude and variability, and neck posture were analyzed for time, condition, and sex effects. No significant effects of condition were observed on the dependent measures evaluated. Discomfort increased over time (neck/shoulder: p < .001), more so in females (eye strain: p < .001). Females' UT activation amplitude was negatively correlated to eye strain in the placebo condition (p = .05).

The Prevalence of and Factors Associated With Neck Pain Among Jazan Adult Population

Background

Neck pain is considered one of the main musculoskeletal conditions affecting the population worldwide. However, it is difficult to identify the precise causes of pain.

Objective

This study aimed to estimate the prevalence of neck pain and its associated factors in the adult population and surrounding districts.

Methods

This cross-sectional study was conducted in Jazan city and the surrounding districts of the Kingdom of Saudi Arabia. A total of 443 adults of both sexes participated in an online questionnaire designed to determine the prevalence of neck pain and the significance of the relationship between neck pain and specific risk factors. The collected data included the participants' characteristics (personal, socioeconomic, demographic, and work-related aspects).

Results

Neck pain was highly prevalent among adults in Jazan city and the surrounding districts, as 347 of 443 participants (78.3%) experienced neck pain, while 96 (21.7%) did not suffer from neck pain. There was a significant relationship between the most common physical positions while using electronic devices and reading and the prevalence of neck pain (p = 0.015). The most common position accompanied by neck pain was the sitting position compared to the positions of lying, walking, or standing (79.7% vs. 67.9%, 60%, and 0%, respectively). No significant association was observed between the prevalence of neck pain and sex, age, monthly income, place of residence, smoking, or the number of hours spent on electronic devices or reading.

Conclusion

This study revealed a high prevalence of neck pain among adults in Jazan, Saudi Arabia, and a remarkable association with people who spend many hours daily using electronic devices, reading, performing work, sitting for a long time, and with lack of exercise.

Gender differences in associating musculoskeletal complaints, housework, electronic device usage and physical exercise for administrative workers

Objectives. This study assessed musculoskeletal complaints (MSCs) in administrative workers, associating MSCs with non-paid housework, home use of electronic devices and physical exercise, while keeping a distinctive gender approach. This may promote the development of more effective preventive measures, by meeting the specific strengths and weaknesses of each gender. Methods. Ninety-six administrative workers (58 women and 38 men) who used computers more than 50% of their working time participated in a cross-sectional study. A questionnaire concerning individual socio-demographic data, habits and lifestyle, and including the Nordic musculoskeletal questionnaire (NMQ), was deployed. Gender-based odds ratios for MSCs in body areas over the previous 12 months and correlation coefficients between habits and lifestyle variables and NMQ variables were computed. Results. Women did not incur a higher risk of MSCs than men. Analysis of the association did not yield meaningful associations for either gender. Results suggest giving future consideration to development of gender-specific preventive measures. Conclusion. Computerized work performed concomitantly with physical exposures outside the workplace showed mixed associations with MSCs, according to gender and depending on the kind of exposure. Results are indicative of the need for development of gender-specific preventive measures.

Burden of neck pain among medical students in Ethiopia

Background

Neck pain is the major cause of morbidity and absenteeism from university lessons among medical students worldwide. Medical students are more exposed and appear to have neck pain because of their length of study to achieve their professional goals. However, up to the knowledge of the researcher, there is a scarcity of literature conducted on prevalence and associated factors of neck pain among medical students in Ethiopia. Therefore, the aim of this study was to determine the prevalence and factors associated with neck pain among medical students at Mekelle University, College of Health Sciences, Tigray, Ethiopia.

Method

Institutional based cross-sectional study was conducted from April 2018 to May 2018. A structured questionnaire adapted from the Nordic musculoskeletal questionnaire was distributed to 422 participants using a self-administered questionnaire in Mekelle University, College of Health Sciences Tigray, Ethiopia. Independent variables which had a significant association were identified using logistic regression models. Results were reported by using texts and frequency distribution tables.

Result

A total of 422 participants involved in this study, with a 99.3% response rate. Previous 12 months self-reported prevalence of neck pain among medical students was found to be 49.2% with 95%CI (44.5–54%). Previous history of neck pain (AOR: 11.811, 95%CI: 5.460–25.549), physical exercise (AOR: 2.044, 95%CI: 1.233–3.387), duration of reading (AOR: 1.502, 95%CI: 0.236–2.780) and awkward posture (AOR: 3.87, 95%CI: 2.311–6.484) were factors significantly associated with neck pain.

Conclusion and recommendation

The current study showed that nearly half of the study participants self-reported to have suffered neck pain in the preceding 12 months. Past history of neck pain, physical exercise, duration of reading and awkward neck posture are likely to be significantly associated neck pain among medical students in Ethiopia. Engaging in consistent physical exercise has a protective effect against neck pain. Therefore, Medical students are recommended to carry out a regular physical exercise for a minimum of twenty to thirty minutes per day.

Prevalence of upper limb pain and disability and its correlates with demographic and personal factors

Purpose

The present study aimed to assess the prevalence of upper limb pain and disability and to investigate potentially correlated factors among university students in Jordan.

Methods

This was a cross-sectional questionnaire-based survey study that was conducted among university students. The upper limb pain and disability were assessed by the Disabilities of the Arm, Shoulder, and Hand (DASH) outcome questionnaire. The DASH outcome questionnaire was distributed to 2100 students from the population of 2 public and 2 private universities in the north of Jordan. Demographic and personal information were collected. Data were analyzed using descriptive statistics and linear regression analysis.

Results

A total of 1929 DASH outcome questionnaires were returned, with a high response rate of 91.86%. The age of the subjects was between 18–28 years (52% male; 48% female). The majority of subjects (85.2%) used at least one smartphone. The majority of them had been using a smartphone for more than 5 years. The prevalence of upper limb pain and disability among university students was 24%. Several factors were found to be significantly connected with upper limb pain and disability among university students, such as smartphone use, computer use,  the presence of musculoskeletal problems, not living with their families, using public transport (bus), and daily housekeeping.

Conclusion

The results of this study can be used globally to promote the health and well-being of university students, improve their academic performance and future career. Identifying high-risk groups will assist in early identifications and prevention programs for upper limb pain and disability among university students.

HUBUNGAN ANTROPOMETRI DENGAN KURSI KERJA DI KANTOR PELAYANAN PERBENDAHARAAN NEGARA MOJOKERTO

Chairs are an important component in determining comfort while sitting or doing a job with sitting. The aim of the research is to analyze the suitability between the size of the table and chair with anthropometry of the employee’s body. The number of respondents is 20 people. The variables of the study are measure of anthropometry and workstation. This is a descriptive research and using cross sectional approach. The measured variables are body anthropometry such as popliteal height, politeal but, hip width, shoulder height, shoulder width, elbow height. Variable work seats include seat height, seat base, length of seat base, width of seat, high backrest, width of backrest, elbow height. The results show that the dimensions of the workstation that corresponds to the body dimensions of the width of the seat base with the width of the hip the height of the backrest with the height of the sitting shoulder and the length of the elbow rest with the length of the forearm Dimensions that are inconsistent with the anthropometry of the body with the height of the chair with the popliteal height the length of the sitting base with popliteal buttock the width of the backrest with shoulder width the height of the elbow rest with the height of the sitting elbow. Conclusion is work chair is not accordance with anthropometry of employees because only 3 dimensions of work chairs are compatible with employee anthropometry.Keywords: anthropometry, chair, dimensions

Gender and posture are significant risk factors to musculoskeletal symptoms during touchscreen tablet computer use

[Purpose] To investigate the prevalence of neck and shoulder symptoms during the use of tablet computer, and to identify the risk factors associated with these symptoms. [Subjects and Methods] A cross-sectional survey was conducted to study tablet computer usage, posture during use, and neck and shoulder symptoms in 412 participants in a school setting. Significant risk factors for musculoskeletal symptoms during tablet computer use were identified. [Results] Overall prevalence of musculoskeletal symptoms during tablet computer use was 67.9% with greater prevalence of neck symptoms (neck: 84.6%; shoulder/upper extremity: 65.4%). Significant risk factors associated with symptoms during use were: current musculoskeletal symptoms, gender, roles, and postural factors including: sitting without back support, sitting with device in lap, and lying on the side and on the back during tablet computer use. A multivariate analysis further showed that the odds for females to have symptoms were 2.059 times higher than males. [Conclusion] The findings revealed that female gender and other postural factors were significantly associated with musculoskeletal symptoms during the use of tablet computer. Among all postural factors, sitting without back support was identified as the most important risk factor for having musculoskeletal symptoms.

Musculoskeletal disorders among first-year Ghanaian students in a nursing college

OBJECTIVE

To estimate the prevalence and extent of MSDs among a sample of freshmen in a nursing college in Ghana.

METHODS

A semi-structured self-reported questionnaire including the Nordic Musculoskeletal Questionnaire (NMQ) was used to collect information on age, gender and musculoskeletal complaints among a random sample of 200 students at a nursing and midwifery college in the Eastern region of Ghana.

RESULTS

Out of the 200 questionnaires administered, 160 were retrieved of which 3 were found to be incomplete and void, yielding a total of 157 evaluable questionnaires, a response rate of 78.5%. One hundred and ten (70.1%) students reported having MSDs in the previous 12 months, of which a total 88 (56.1%) suffered disabling effects, while 70(44.6%) students reported having MSDs in the past 7 days. The prevalence of MSDs in the different body regions was generally low with clustered distribution in the neck, upper back, wrists/hands and lower back.

CONCLUSION

Nursing students are at reasonably high risk of MSDs. Strategies to prevent this important public health problem amongst future generation of nursing students must be given utmost priority. This study provides the baseline data for more elaborative studies in the Ghanaian population.

Fatigue development in the finger flexor muscle differs between keyboard and mouse use

PURPOSE

The aim of the present study was to determine whether there were any physiological changes in the muscle as a result of intensive computer use.

METHODS

Using a repeated measures experimental design, eighteen subjects participated in four different 8-h conditions: a control (no exposure) condition and three exposure conditions comprised of 6 h of computer use (keyboard, mouse, and combined keyboard and mouse use) followed by 2 h of recovery. In each condition, using 2 Hz neuromuscular electrical stimulation, eight temporal measurements were collected to evaluate the fatigue state (twitch force, contraction time, and ½ relaxation time) of the right middle finger Flexor Digitorum Superficialis (FDS) muscle before, during, and after computer use.

RESULTS

The results indicated that 6 h of keyboard, mouse, and combined mouse and keyboard use all caused temporal fatigue-related changes in physiological state of the FDS muscle. Keyboard use resulted in muscle potentiation, which was characterized by approximately 30% increase in twitch force (p < 0.0001) and 3% decrease (p = 0.04) in twitch durations. Mouse use resulted in a combined state of potentiation and fatigue, which was characterized by an increase in twitch forces (p = 0.002) but a prolonging (11 %) rather than a shortening of twitch durations (p < 0.0001).

CONCLUSIONS

When comparing mouse and keyboard use, the more substantial change in the physiological state of the muscle with mouse use (potentiation and fatigue compared to just potentiation with keyboard use) provides some physiological evidence which may explain why mouse use has a greater association with computer-related injuries.

Office workers' computer use patterns are associated with workplace stressors

This field study examined associations between workplace stressors and office workers' computer use patterns. We collected keyboard and mouse activities of 93 office workers (68F, 25M) for approximately two work weeks. Linear regression analyses examined the associations between self-reported effort, reward, overcommitment, and perceived stress and software-recorded computer use duration, number of short and long computer breaks, and pace of input device usage. Daily duration of computer use was, on average, 30 min longer for workers with high compared to low levels of overcommitment and perceived stress. The number of short computer breaks (30 s-5 min long) was approximately 20% lower for those with high compared to low effort and for those with low compared to high reward. These outcomes support the hypothesis that office workers' computer use patterns vary across individuals with different levels of workplace stressors.

Differences in typing forces, muscle activity, comfort, and typing performance among virtual, notebook, and desktop keyboards

The present study investigated whether there were physical exposure and typing productivity differences between a virtual keyboard with no tactile feedback and two conventional keyboards where key travel and tactile feedback are provided by mechanical switches under the keys. The key size and layout were same across all the keyboards. Typing forces; finger and shoulder muscle activity; self-reported comfort; and typing productivity were measured from 19 subjects while typing on a virtual (0 mm key travel), notebook (1.8 mm key travel), and desktop keyboard (4 mm key travel). When typing on the virtual keyboard, subjects typed with less force (p's < 0.0001) and had lower finger flexor/extensor muscle activity (p's < 0.05). However, the lower typing forces and finger muscle activity came at the expense of a 60% reduction in typing productivity (p < 0.0001), decreased self-reported comfort (p's < 0.0001), and a trend indicating an increase in shoulder muscle activity (p's < 0.10). Therefore, for long typing sessions or when typing productivity is at a premium, conventional keyboards with tactile feedback may be more suitable interface.

Comparison of the Lumbar Flexion Angle and EMG Activity in Trunk Muscles in Individuals with and without Limited Hip Flexion Range of Motion during Visual Display Terminal Work with Cross-Legged Sitting

[Purpose] The purpose of this study was to compare the lumbar flexion angle and electromyography (EMG) measurements of trunk muscle activity in individuals with and without limited hip flexion range of motion (ROM) during visual display terminal (VDT) work with cross-legged sitting. [Subjects] The 15 participants included a control group with sufficient hip flexion ROM (n = 7) and an experimental group with limited hip flexion ROM (n = 8). [Methods] All subjects performed VDT work with cross-legged sitting. The lumbar flexion angle was measured using a three-dimensional motion capture system, and the trunk muscle activity was recorded using a surface EMG system during VDT work with cross-legged sitting. The differences in trunk flexion angle and trunk muscle activity between the two groups were analyzed using independent t-tests. [Results] The lumbar flexion angle was significantly greater in the experimental group than the control group, although trunk muscle activity did not differ between the two groups. [Conclusion] These findings suggest that limited hip flexion leads to greater lumbar flexion during cross-legged sitting.

Biomechanics and performance when using a standard and a vertical computer mouse

OBJECTIVE

to compare the biomechanics and performance while using a vertical computer mouse (VM) and a standard mouse (SM).

METHODS

muscle activation (electromyography), forearm movements (electrogoniometers), performance (Fitts' Law test) and satisfaction (questionnaire) of 16 subjects were evaluated.

RESULTS

there were significant differences between the VM and the SM, respectively, on motion (28° vs. 42° pronation, p = 0.001; 5° ulnar vs. 7° radial deviation, p = 0.016) and muscle activity (13% vs. 16% of extensor carpi activity, p = 0.006; 10% vs. 13% extensor digitorum activity, p = 0.001). VM user satisfaction was good (68); however, time to target was longer (4.2 vs. 3.4 s, p < 0.001).

CONCLUSIONS

using the VM decreased wrist pronation and lowered wrist extensor muscle activity, but additional training and familiarisation time may be required to improve user performance.

PRACTITIONER SUMMARY

Using a vertical mouse can decrease the exposure to biomechanical risk factors for computer mouse use-related musculoskeletal disorders. Using a vertical computer mouse resulted in less wrist pronation and lower wrist extensor muscle activity. But, training and familiarisation are required.

Efficient assessment of exposure to manual lifting using company data

The objective of this study, based on an extensive dataset on manual materials handling during scaffolding, was to explore whether routinely collected company data can be used to estimate exposure to manual lifting. The number of manual lifts of scaffold parts while constructing/dismantling scaffolds was well predicted by the number of scaffolders in the team and the type of worksite, in combination with company data of either the number of scaffold parts or the scaffold volume. The proportion of explained variance in the number of lifts ranged from 77% to 92%, depending on the variables in the model. Data on scaffold parts and scaffold volume can easily be obtained from the company's administration, since this is its usual paperwork supporting logistics and customer invoicing, respectively. We conclude that company data can be a promising source of information for ergonomic practitioners and researchers, to support assessment of manual lifting in scaffolding.

The predictive validity of the RSI QuickScan questionnaire with respect to arm, shoulder and neck symptoms in computer workers

The aim of this study was to determine whether results from the RSI QuickScan questionnaire on risk factors for arm, shoulder and neck symptoms can predict future arm, neck and shoulder symptoms in a population of computer workers. For this prospective cohort study, with a follow-up of 24 months, 3383 workers who regularly worked with a computer were approached. Generalised estimating equations (GEE) with 6, 12, 18 and 24 months time lags were used to determine whether high exposure was related to symptoms at follow-up. The results showed that high scores on 9 out of 13 scales, including previous symptoms, were significantly related to arm, shoulder and neck symptoms at follow-up. These results provide support for the predictive validity of the RSI QuickScan questionnaire.

PRACTITIONER SUMMARY

The results showed that high scores on 9 out of 13 scales, including previous symptoms, were significantly related to arm, shoulder and neck symptoms at follow-up. The RSI QuickScan questionnaire may be recommended as a tool in the identification of computer workers who should be targeted with interventions aimed at prevention of future symptoms.

Shoulder and neck muscle activities during typing with articulating forearm support at different heights

Use of forearm support is known to reduce physical stress of computer users, but research about how to properly position the forearm support is insufficient. This study was aimed to determine whether the height of forearm support influences muscular loads during typing. Twenty four subjects performed a typing task with a pair of articulating forearm support at three different heights as well as without any support, while shoulder, neck and forearm muscle activities and posture data were recorded. Typing with the support at resting elbow height produced significantly (p < 0.05) lower shoulder and neck muscle activities than that of no support condition. Typing with the support at heights higher than the resting elbow height produced significantly greater shoulder and neck muscle activities compared to the no support condition. Results suggest that forearm support can help computer users lessen physical stress in typing, but only when the supports are positioned at resting elbow height. Practitioner Summary: Use of forearm support is known to alleviate physical stress of PC users in computer works such as typing. This experimental study addressed the importance of proper positioning of forearm support by comparing neck and upper extremity muscle activities between conditions with varying heights of forearm support in keyboard typing.

Risk factors for the onset and persistence of neck pain in undergraduate students: 1-year prospective cohort study

Background

Although neck pain is common in young adulthood, studies on predictive factors for its onset and persistence are scarce. It is therefore important to identify possible risk factors among young adults so as to prevent the development of neck pain later in life.

Methods

A prospective study was carried out in healthy undergraduate students. At baseline, a self-administered questionnaire and standardized physical examination were used to collect data on biopsychosocial factors. At 3, 6, 9, and 12 months thereafter, follow-up data were collected on the incidence of neck pain. Those who reported neck pain on ≥ 2 consecutive follow-ups were categorized as having persistent neck pain. Two regression models were built to analyze risk factors for the onset and persistence of neck pain.

Results

Among the recruited sample of 684 students, 46% reported the onset of neck pain between baseline and 1-year follow-up, of whom 33% reported persistent neck pain. The onset of neck pain was associated with computer screen position not being level with the eyes and mouse position being self-rated as suitable. Factors that predicted persistence of neck pain were position of the keyboard being too high, use of computer for entertainment < 70% of total computer usage time, and students being in the second year of their studies.

Conclusion

Neck pain is quite common among undergraduate students. This study found very few proposed risk factors that predicted onset and persistence of neck pain. The future health of undergraduate students deserves consideration. However, there is still much uncertainty about factors leading to neck pain and more research is needed on this topic.

University students' notebook computer use: lessons learned using e-diaries to report musculoskeletal discomfort

The objective of this pilot study was to identify if notebook accessories (ergonomic chair, desktop monitor and notebook riser) combined with a wireless keyboard, mouse and participatory ergonomics training would have the greatest impact on reducing self-reported upper extremity musculoskeletal discomfort in university students. In addition to pre-post computing and health surveys, the Ecological Momentary Assessment was used to capture change in discomfort over time using a personal digital assistant (PDA) as the e-diary. The PDA was programmed with a survey containing 45 questions. Four groups of university students were randomised to either intervention (three external computer accessories) or to control. Participants reported less discomfort with the ergonomic chair and notebook riser based on the pre-post survey data and the e-diary/PDA ANOVA analysis. However, the PDA data, adjusted for the effect of hours per day of computer use, showed no benefit of the chair and limited benefit from the riser. Statement of Relevance:University students' use of notebook computers has increased. This study found evidence of a positive effect of an adjustable chair or notebook riser when combined with ergonomic training on reducing discomfort. Daily notebook computer use of 4 h was confirmed as a risk factor. Without some form of ergonomic intervention, these students are likely to enter the workforce with poor computing habits, which places them on the road to future injuries as technology continues to play a dominant role in their lives.

Validation of a software program for measuring fatigue-related changes in keystroke durations

Intensive computer use has been associated with musculoskeletal disorders (MSDs). Although the underlying mechanisms are still not fully understood, muscle fatigue is thought to be a contributing factor. Previous studies have shown that keystroke durations are related to muscle twitch durations and may be used as a surrogate measure of muscle fatigue. Software tools have been developed to measure keystroke durations; however, the accuracy of these programs may be influenced by the computer and/or the operating system (OS). Keystrokes were collected from six subjects and analyzed to determine whether there were any differences in keystroke durations measured by an OS-dependant software program and keystrokes collected directly from the keyboard using a USB analyzer (gold standard). The results demonstrated that the OS-dependant software program underestimated keystroke durations by 3.8 ms (103.5 vs. 107.3 ms; p < 0.0001) but keystroke durations at the individual level were highly correlated between the two systems (R(2) = 0.997). Despite the small differences, the high correlation between systems indicated that the software program could be used to collect keystroke durations.

Musculoskeletal symptoms among mobile hand-held device users and their relationship to device use: A preliminary study in a Canadian university population

The study aims were, in a population of university students, staff, and faculty (n = 140), to: 1) determine the distribution of seven measures of mobile device use; 2) determine the distribution of musculoskeletal symptoms of the upper extremity, upper back and neck; and 3) assess the relationship between device use and symptoms. 137 of 140 participants (98%) reported using a mobile device. Most participants (84%) reported pain in at least one body part. Right hand pain was most common at the base of the thumb. Significant associations found included time spent internet browsing and pain in the base of the right thumb (odds ratio 2.21, 95% confidence interval 1.02-4.78), and total time spent using a mobile device and pain in the right shoulder (2.55, 1.25-5.21) and neck (2.72, 1.24-5.96). Although this research is preliminary, the observed associations, together with the rising use of these devices, raise concern for heavy users.

Software-recorded and self-reported duration of computer use in relation to the onset of severe arm-wrist-hand pain and neck-shoulder pain

Objectives

In both science and media, the adverse effects of a long duration of computer use at work on musculoskeletal health have long been debated. Until recently, the duration of computer use was mainly measured by self-reports, and studies using more objective measures, such as software-recorded computer duration, were lacking. The objective of this study was to examine the association between duration of computer use at work, measured with software and self-reports, and the onset of severe arm–wrist–hand and neck–shoulder symptoms.

Methods

A 2-year follow-up study was conducted between 2004 and 2006 among 1951 office workers in The Netherlands. Self-reported computer duration and other risk factors were collected at baseline and at 1-year follow-up. Computer use at work was recorded continuously with computer software for 1009 participants. Outcome questionnaires were obtained at baseline and every 3 months during follow-up. Cases were identified based on the transition within 3 months of no or minor symptoms to severe symptoms.

Results

Self-reported duration of computer use was positively associated with the onset of both arm–wrist–hand (RR 1.9, 95% CI 1.1 to 3.1 for more than 4 h/day of total computer use at work) and neck–shoulder symptoms (RR 1.5, 95% CI 1.1 to 2.0 for more than 4 h/day of mouse use at work). The recorded duration of computer use did not show any statistically significant association with the outcomes.

Conclusions

In the present study, no association was found between the software-recorded duration of computer use at work and the onset of severe arm–wrist–hand and neck–shoulder symptoms using an exposure window of 3 months. In contrast, a positive association was found between the self-reported duration of computer use at work and the onset of severe arm–wrist–hand and neck–shoulder symptoms. The different findings for recorded and self-reported computer duration could not be explained satisfactorily.

Daily self-reports resulted in information bias when assessing exposure duration to computer use

BACKGROUND

Self-reported exposure duration to computer use is widely used in exposure assessment, and this study examined the associated information bias in a repeated measures setting.

METHODS

For 3 weeks, 30 undergraduate students reported daily cumulative computer-use duration and musculoskeletal symptoms at four random times per day. Usage-monitor software installed onto participant's personal computers provided the reference measure. We compared daily self-reported and software-recorded duration, and modeled the effect of musculoskeletal symptoms on observed differences.

RESULTS

The relationships between daily self-reported and software-recorded computer-use duration varied greatly across subject with Spearman's correlations ranging from -0.22 to 0.8. Self-reports generally overestimated computer use when software-recorded durations were less than 3.6 hr, and underestimated when above 3.6 hr. Experiencing symptoms was related to a 0.15-hr increase in self-reported duration after controlling for software-recorded duration.

CONCLUSIONS

Daily self-reported computer-use duration had a weak-to-moderate correlation with software-recorded duration, and their relationship changed slightly with musculoskeletal symptoms. Self-reports resulted in both non-differential and differential information bias.

Differences in computer exposure between university administrators and CAD draftsmen

This study utilized an external logger system for onsite measurements of computer activities of two professional groups-twelve university administrators and twelve computer-aided design (CAD) draftsmen. Computer use of each participant was recorded for 10 consecutive days-an average of 7.9+/-1.8 workdays and 7.8+/-1.5 workdays for administrators and draftsmen, respectively. Quantitative parameters computed using recorded data were daily dynamic duration (DD) and static duration, daily keystrokes, mouse clicks, wheel scrolling counts, mouse movement and dragged distance, average typing and clicking rates, and average time holding down keys and mouse buttons. Significant group differences existed in the number of daily keystrokes (p<0.0005) and mouse clicks (p<0.0005), mouse distance moved (p<0.0005), typing rate (p<0.0001), daily mouse DD (p<0.0001), and keyboard DD (p<0.005). Both groups had significantly longer mouse DD than keyboard DD (p<0.0001). Statistical analysis indicates that the duration of computer use for different computer tasks cannot be represented by a single formula with same set of quantitative parameters as those associated with mouse and keyboard activities. Results of this study demonstrate that computer exposure during different tasks cannot be estimated solely by computer use duration. Quantification of onsite computer activities is necessary when determining computer-associated risk of musculoskeletal disorders. Other significant findings are discussed.

Differences in prevalence of self-reported musculoskeletal symptoms among computer and non-computer users in a Nigerian population: a cross-sectional study

BACKGROUND

Literature abounds on the prevalent nature of Self Reported Musculoskeletal Symptoms (SRMS) among computer users, but studies that actually compared this with non computer users are meagre thereby reducing the strength of the evidence. This study compared the prevalence of SRMS between computer and non computer users and assessed the risk factors associated with SRMS.

METHODS

A total of 472 participants comprising equal numbers of age and sex matched computer and non computer users were assessed for the presence of SRMS. Information concerning musculoskeletal symptoms and discomforts from the neck, shoulders, upper back, elbows, wrists/hands, low back, hips/thighs, knees and ankles/feet were obtained using the Standardized Nordic questionnaire.

RESULTS

The prevalence of SRMS was significantly higher in the computer users than the non computer users both over the past 7 days (chi2 = 39.11, p = 0.001) and during the past 12 month durations (chi2 = 53.56, p = 0.001). The odds of reporting musculoskeletal symptoms was least for participants above the age of 40 years (OR = 0.42, 95% CI = 0.31-0.64 over the past 7 days and OR = 0.61; 95% CI = 0.47-0.77 during the past 12 months) and also reduced in female participants. Increasing daily hours and accumulated years of computer use and tasks of data processing and designs/graphics significantly (p < 0.05) increased the risk of reporting musculoskeletal symptoms. Over the past 7 day duration, the neck (33.9%) and low back (11.4%) had highest prevalence of SRMS for the computer and non computer users respectively.

CONCLUSION

The prevalence of SRMS was significantly higher in the computer users than the non computer users and younger age, being male, working longer hours daily, increasing years of computer use, data entry tasks and computer designs/graphics were the significant risk factors for reporting musculoskeletal symptoms among the computer users. Computer use may explain the increase in prevalence of SRMS among the computer users.

Evidence-based guidelines for the wise use of computers by children: physical development guidelines

Computer use by children is common and there is concern over the potential impact of this exposure on child physical development. Recently principles for child-specific evidence-based guidelines for wise use of computers have been published and these included one concerning the facilitation of appropriate physical development. This paper reviews the evidence and presents detailed guidelines for this principle. The guidelines include encouraging a mix of sedentary and whole body movement tasks, encouraging reasonable postures during computing tasks through workstation, chair, desk, display and input device selection and adjustment and special issues regarding notebook computer use and carriage, computing skills and responding to discomfort. The evidence limitations highlight opportunities for future research. The guidelines themselves can inform parents and teachers, equipment designers and suppliers and form the basis of content for teaching children the wise use of computers. STATEMENT OF RELEVANCE: Many children use computers and computer-use habits formed in childhood may track into adulthood. Therefore child-computer interaction needs to be carefully managed. These guidelines inform those responsible for children to assist in the wise use of computers.

Differences in muscle load between computer and non-computer work among office workers

Introduction of more non-computer tasks has been suggested to increase exposure variation and thus reduce musculoskeletal complaints (MSC) in computer-intensive office work. This study investigated whether muscle activity did, indeed, differ between computer and non-computer activities. Whole-day logs of input device use in 30 office workers were used to identify computer and non-computer work, using a range of classification thresholds (non-computer thresholds (NCTs)). Exposure during these activities was assessed by bilateral electromyography recordings from the upper trapezius and lower arm. Contrasts in muscle activity between computer and non-computer work were distinct but small, even at the individualised, optimal NCT. Using an average group-based NCT resulted in less contrast, even in smaller subgroups defined by job function or MSC. Thus, computer activity logs should be used cautiously as proxies of biomechanical exposure. Conventional non-computer tasks may have a limited potential to increase variation in muscle activity during computer-intensive office work.

The effects of walking and cycling computer workstations on keyboard and mouse performance

OBJECTIVE

This study aimed to determine the effects of active workstation designs on speed and error during typing, mouse pointing, and combined type and mouse-use tasks.

BACKGROUND

Office ergonomics has focused on musculoskeletal disorder prevention; however, increasing computer-based work also increases health risks associated with inactivity. Workstations allowing computer users to walk or cycle while performing computer tasks have been shown to demand sufficient energy expenditure to result in significant health benefits. However the performance effects of being active while using a computer have not been documented.

METHOD

Thirty office workers (16 female, 15 touch typists) performed standardized computer tasks in six workstation conditions: sitting, standing, walking at 1.6 km/h and 3.2 km/h, and cycling at 5 and 30 watts. Performance, perceived performance, and heart rate were measured.

RESULTS

Computer task performance was lower when walking and slightly lower when cycling, compared with chair sitting. Standing performance was not different from sitting performance. Mouse performance was more affected than typing performance. Performance decrements were equal for females and males and for touch typists and nontouch typists.

CONCLUSION

Performance decrements maybe related to both biomechanical and cognitive processes. Active workstations may be less suitable for mouse-intensive work and susceptible users.

APPLICATION

Although active workstations may result in some decrement in performance, their ability to increase daily energy expenditure may make them a feasible solution for workplace inactivity.

Internal consistency, test-retest reliability and concurrent validity of a questionnaire on work-related exposure related to arm, shoulder and neck symptoms in computer workers

The aim of this study was to determine the internal consistency, test-retest reliability and concurrent validity of the RSI QuickScan, a newly developed questionnaire that aims to identify the presumed risk factors for neck, shoulder and arm symptoms in a population of computer workers. The internal consistency was calculated using item analysis. The test-retest reliability and concurrent validity were analysed by calculating the percentage of agreement, Cohen's Kappa and the Ppositive and Pnegative. The concurrent validity was also tested by comparing the results from the new questionnaire with those from the original questionnaires that the current questionnaire was based on, on-site expert observations and direct measurements. The results indicate that the RSI QuickScan is a measurement tool with acceptable internal consistency, reliability and concurrent validity. The questionnaire can be used as a means to rapidly collect data on a large population of office workers and at low cost.

A wide range of activity duration cutoffs provided unbiased estimates of exposure to computer use

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.

Computer work duration and its dependence on the used pause definition

Several ergonomic studies have estimated computer work duration using registration software. In these studies, an arbitrary pause definition (Pd; the minimal time between two computer events to constitute a pause) is chosen and the resulting duration of computer work is estimated. In order to uncover the relationship between the used pause definition and the computer work duration (PWT), we used registration software to record usage patterns of 571 computer users across almost 60,000 working days. For a large range of Pds (1-120 s), we found a shallow, log-linear relationship between PWT and Pds. For keyboard and mouse use, a second-order function fitted the data best. We found that these relationships were dependent on the amount of computer work and subject characteristics. Comparison of exposure duration from studies using different pause definitions should take this into account, since it could lead to misclassification. Software manufacturers and ergonomists assessing computer work duration could use the found relationships for software design and study comparison.

Typing keystroke duration changed after submaximal isometric finger exercises

A repeated-measures laboratory experiment tested whether keystroke duration during touch-typing changes after a finger performs submaximal isometric flexion exercises. Fourteen right-handed touch-typists used right ring finger to perform three 15-min exercise conditions, two isometric exercises and a no-force condition, each on a separate day. Before and after each exercise condition, typing keystroke duration and isometric force elicited by electrical stimulation were measured for right ring finger. Keystroke duration of right ring finger decreased by 5% (6 ms, P < 0.05) immediately after the exercises but not after the no-force condition. Peak isometric finger force elicited by electrical stimulation decreased by 17-26% (P < 0.05) for the flexor digitorum superficialis and decreased by 4-8% for the extensor digitorum communis after the isometric exercises. After the finger was exposed to isometric exercises, changes in typing keystroke duration coincided with changes in the physiological state of the finger flexor and extensor muscles.

Computer use patterns associated with upper extremity musculoskeletal symptoms

INTRODUCTION

Over half of surveyed college students are experiencing pain they are attributing to computer use. The study objective was to evaluate the effect of computing patterns on upper extremity musculoskeletal symptoms.

METHODS

Symptom experiences and computing/break patterns were reported several times daily over three weeks for 30 undergraduate students over a semester. Two-level logistic regression models described the daily association between each computing pattern and both any and moderate or greater symptom experienced, adjusting for covariates.

RESULTS

The associations between most computing/break patterns and experiencing any symptoms were positive: total hours of computer use adjOR = 1.1 (90% CI 1.1-1.2), 1-2 breaks versus none adjOR = 1.3 (90% CI 0.9-1.9), 3-6 breaks versus none adjOR = 1.5 (90% CI 1.1-2.2), >15 min break versus none adjOR = 1.6 (90% CI 1.1-2.2), and number of stretch breaks adjOR = 1.3 (90% CI 1.1-1.5). However, breaks for less than 15 min were negatively associated with experiencing any symptoms: adjOR = 0.6 (90% CI 0.5-0.9). The associations between most computing/break patterns and experiencing moderate or greater symptoms were positive: total hours of computer use OR = 1.1 (90% CI 1.1-1.2), 1-2 breaks and 5-6 breaks versus none OR = 1.8 (90% CI 1.1-2.9), 7-8 breaks versus none OR = 2.0 (1.0-4.2), >15 min break versus none 1.8 (1.1-3.1), and number of stretch breaks OR = 1.3 (1.0-1.5).

CONCLUSION

Computing/break patterns were consistently associated with experiencing symptoms. Our findings suggest evaluating breaks with computing duration (computing patterns) is more informative than assessing computing duration alone and can be used to better design ergonomic training programs for student populations that incorporate break times.