Postures,typing strategies,and gender differences in mobile device usage: An observational study

Mobile device text messaging and other typing is rapidly increasing worldwide. A checklist was utilized to characterize joint postures and typing styles in individuals appearing to be of college age (n = 859) while typing on their mobile devices in public. Gender differences were also ascertained. Almost universally, observed subjects had a flexed neck (91.0%, n = 782), and a non-neutral typing-side wrist (90.3%, n = 776). A greater proportion of males had protracted shoulders (p < 0.01, χ² test), while a greater proportion of females had a typing-side inner elbow angle of <90°, particularly while standing (p = 0.03, χ² test). 46.1% of subjects typed with both thumbs (two hands holding the mobile device). Just over one-third typed with their right thumb (right hand holding the mobile device). No difference in typing styles between genders was found. Future research should determine whether the non-neutral postures identified may be associated with musculoskeletal disorders.     

Predictive validity of the Hand Arm Risk assessment Method (HARM)

The Hand Arm Risk assessment Method (HARM) is a simplified risk assessment method for determining musculoskeletal symptoms to the arm, neck and/or shoulder posed by hand-arm tasks of the upper body. The purpose of this study was to evaluate the predictive validity of HARM using data collected from a three year prospective cohort Study on Musculoskeletal disorders, Absenteeism and Health (SMASH). Structured observations of video recordings using HARM were made of 88 participants performing hand-arm tasks. These video recordings were made at baseline of the SMASH study, whereas self-reported musculoskeletal symptoms were assessed both at baseline and during a three year follow-up. The receiver operating characteristic (ROC) curves showed an area under the curve (AUC) of 0.75 (CI: 0.65–0.86) for symptoms at baseline and 0.70 (CI: 0.58–0.83) for symptoms during follow-up. For a HARM score of 50, the sensitivity and specificity were 64% and 79% at baseline and 53% and 82% during follow up. Participants with a HARM score of 50 or more (considered a high risk) had a significantly higher risk of upper limb symptoms than those with a HARM score of less than 50 at baseline (OR = 5.31; 95%CI: 2.10–13.39) and 3 year follow-up (OR = 5.11; (95%CI: 1.61–16.27). This study has shown that HARM can be used to assess work tasks of the hands and arms and discriminate between tasks that pose a high or low risk of neck or upper limb symptoms.     

Mobile touch screen device use and associations with musculoskeletal symptoms and visual health in a nationally representative sample of Singaporean adolescents

This study aimed to describe contemporary technology use, especially smartphones and tablets (mobile touch screen devices), and examine associations with musculoskeletal symptoms and visual health among adolescents in Singapore. A representative sample of 1884 adolescents (50.4% girls) from grades primary 5 to post-secondary (10–18?years old), recruited from 13 schools, completed an online questionnaire in class. Total technology use was high, with smartphone duration being highest (mean?=?264 [SD?=?243] min/day). Patterns of use, including multitasking and bout length, were influenced by gender, school level, type of device and activities. Musculoskeletal discomfort and visual symptoms were commonly reported. After adjusting for potential confounders, more hours/day of smartphone use was associated with increased risk of neck/shoulders, upper back, arms and wrist/hand discomfort (OR?=?1.04[95%CI?=?1.01–1.07] to 1.07[1.03–1.10]) and visual symptoms (OR?=?1.05[1.02–1.08]), but was associated with decreased odds of myopia (OR?=?0.97[0.94–0.99]). No significant associations were found for tablet use.

Practitioner Summary: 1884 adolescents in Singapore completed an in-depth questionnaire regarding their use of technology. The smartphone was the device with the highest usage, and greater smartphone use was associated with increased odds of musculoskeletal and visual symptoms. High use of smartphones has physical health implications for adolescents.     

Medical device on pharmacists' work-related musculoskeletal complaints and burnouts

This study analysed the total number of consumed vials of chemotherapy drugs during the year 2007 to determine workloads, and investigated the effects of using the Spike medical device in contrast to the use of traditional needles on oncology pharmacists' dispensing time, muscle soreness, work-related burnout and fatigue symptoms. Work-related burnout and physiological symptoms were measured using the Copenhagen Burnout Inventory (CBI) and a visual analogue pain scale. The Spike device significantly reduced the time spent in drawing up fluorouracil (39.46 ± 9.43 s vs. 57.13 ± 13.47 s) or cisplatin (29.65 ± 11.22 s vs. 60.93 ± 20.54 s) compared with traditional needles (P < 0.001). The CBI burnout score improved significantly with the Spike device (53.21 ± 8.58 vs. 73.21 ± 5.42; P = 0.007) because finger and palm muscle soreness complaints and subjective fatigue symptoms for eye tiredness and shoulder–wrist pain were significantly reduced (P < 0.05).

Practitioner Summary

The pharmacist needs to exert hand strength to counter the vial back-suction pressure to draw out the medical liquid, and confirm the volume during the drawing antineoplastic drug procedure. This study aimed to determine the effects of using a medical device, instead of a needle, on pharmacists' work-related musculoskeletal complaints and burnouts.     

The combined effect of physical,psychosocial/organisational and/or environmental risk factors on the presence of work-related musculoskeletal symptoms and its consequences

This study assessed the combined effect of physical and psychosocial/organisational and/or environmental factors on the presence of musculoskeletal symptoms (MSS) and its consequences (reduced activities and absenteeism due to MSS) in a random sample of 3003 workers in New Zealand. By telephone interview, participants reported their current workplace exposures and MSS (neck/shoulder, arm/elbow, wrist and low back) and its consequences. Data were analysed using multivariable logistic regression. Combined exposure to physical and psychosocial/organisational and/or environmental factors increased the odds of MSS in the neck/shoulder (OR 3.14, 95% CI 1.79–5.52), arms/elbow regions (OR 4.14, 95% CI 2.21–7.76) and low back (OR 1.74, 95% CI 1.28–2.37) and its consequences, i.e. reduced activities due to neck/shoulder symptoms (OR 5.45, 95% CI 2.28–13.00), absenteeism due to neck/shoulder symptoms (OR 5.19, 95% CI 2.24–12.01) and absenteeism due to low back symptoms (OR 4.37, 95% CI 2.92–6.53). In contrast, favourable psychosocial/organisational work conditions reduced the odds of wrist symptoms due to poor physical work conditions (OR 2.19, 95% CI 1.44–3.34). We conclude that to reduce MSS and its consequences, employers need to adopt a multifaceted approach: concentrate on improving physical conditions as well as the psychosocial/organisational and environmental aspects of the working environment.     

A comparison of muscle activity in using touchscreen smartphone among young people with and without chronic neck–shoulder pain

This study aimed to examine differences in muscle activity between young people with and without neck–shoulder pain (n = 20 in each group), when they performed texting on a smartphone. Texting was compared between using both hands (‘bilateral texting’) and with only one hand (‘unilateral texting’). Texting tasks were also compared with computer typing. Surface electromyography from three proximal postural muscles and four distal hand/thumb muscles on the right side was recorded. Compared with healthy controls, young people with neck–shoulder pain showed altered motor control consisting of higher muscle activity in the cervical erector spinae and upper trapezius when performing texting and typing tasks. Generally, unilateral texting was associated with higher muscle loading compared with bilateral texting especially in the forearm muscles. Compared with computer typing, smartphone texting was associated with higher activity in neck extensor and thumb muscles but lower activity in upper and lower trapezius as well as wrist extensors.     

The prevalence of musculoskeletal symptoms among British Columbia sonographers

A survey (n = 211, 92% response rate) was carried out to determine baseline prevalence of musculoskeletal symptoms and identify related biomechanical, psychosocial, work organization and demographic factors among the population of sonographers in British Columbia, Canada. Ninety-one percent of respondents reported musculoskeletal pain or discomfort that they associated with the work tasks of scanning. Almost half reported frequent and severe symptoms. The neck, shoulder, and upper back were the main symptomatic body sites. A very small minority were absent from work due to the symptoms, with more than two thirds of respondents reporting working in pain. Bivariate analyses found significant associations between scanning time, static postures, psychosocial factors, and degree of musculoskeletal symptoms.     

Neck kinematics and muscle activity during mobile device operations

Neck pain is a significant health problem due to its high incident rates and economic costs. Increased use of touch screen mobile devices is becoming pervasive in the modern society and may further influence this already prevalent health problem. However, our current understanding of the cervical spine biomechanics during the operation of touch screen mobile devices is very limited. This study evaluated the neck extensor muscle activities and the kinematics of the cervical spine during the operation of a touch screen tablet and a smart phone. Three-variables, DEVICE, LOCATION and TASK were treated as the independent variables. NASA TLX revealed that “Gaming” was the least difficult task and “Typing” was the most difficult task. Participants of this study maintained significantly deeper neck flexion when operating a smart phone (44.7°), with the mobile devices set on a table (46.4°), and while performing a “Typing” task (45.6°). Lower levels of neck muscle activities were observed while performing a “Reading” task and holding mobile devices with hand. Lower levels of neck muscle activities were also observed when using a smart phone vs. a tablet, however such change was statistically insignificant.Relevance to industryThe current study demonstrated that users maintain deep neck flexion when using touchscreen mobile devices. In the recent years, there is an increasing popularity of mobile smart devices in various occupational environments. The findings of this study may be useful in implementing human-centered task designs to reduce neck injury risks among mobile device users.     

Mobile technology dominates school children’s IT use in an advantaged school community and is associated with musculoskeletal and visual symptoms

This paper describes the contemporary use of information technology devices by children in a socio-educationally advantaged school. A sample of 924 children (50% girls) from grades 5 to 12 (ages 10–19 years) completed an online survey in class. Total daily technology use was high and similar for girls (mean 219 (SD 148) mins/day) and boys (207 (142), p=.186). Tablet computer was the dominant device used in grades 5–9, with laptop computer the dominant device in grades 10–12. Patterns of exposure were influenced by gender, device, grade and purpose of use interactions. For example, girls used mobile phones more than boys for social purposes for grades 10 and 11, but not grade 12. Whilst children’s attitudes to technology use were positive, musculoskeletal and visual symptoms were commonly reported. Hours/day tablet and phone use was related to neck/shoulder discomfort (OR = 1.07; 1.13) and visual symptoms (OR = 1.10; 1.07).

Practitioner Summary: Technology use by children appears to be quite different now to a decade ago. This paper describes contemporary school children’s use of various devices for various purposes. The survey of >900 children found high technology use, dominated by new mobile technologies, and associations with musculoskeletal and visual symptoms.     

Gender difference in mobile phone use and the impact of digital device exposure on neck posture

This cross-sectional study aimed to identify gender differences in the cervical postures when young adults were using mobile phones, as well as the correlations between the postures and the digital devices use (computer and mobile phone). Questionnaires regarding the habits of computer and mobile phone use were administrated to 429 subjects aged from 17 to 33 years old (19.75 ± 2.58 years old). Subjects were instructed to stand habitually and use a mobile phone as in daily life; the sagittal head and cervical postures were measured by head flexion, neck flexion angle and gaze angle. Male participants had a significantly larger head flexion angle (96.41° ± 12.23° vs. 93.57° ± 12.62°, p = 0.018) and neck flexion angle (51.92° ± 9.55° vs. 47.09° ± 9.45°, p < 0.001) than females. There were significant differences in head (F = 3.62, p = 0.014) and neck flexion (F = 3.99, p = 0.009) between different amounts of computer use.

Practitioner Summary: We investigated possible gender differences in head and neck postures of young adults using mobile phones, as well as the potential correlations between these postures and digital device use. We found that males displayed larger head and neck flexion angles than females, which were associated with the amount of computer use.     

Investigation of musculoskeletal symptoms and ergonomic risk factors among female sewing machine operators in Turkey

This cross-sectional study aimed to identify the prevalence of musculoskeletal symptoms and ergonomic risks in female sewing machine operators at a textile company. The study sample comprised all female sewing machine operators in the company. The sample included 283 sewing machine operators. Data were collected through the use of the adapted Nordic Musculoskeletal Questionnaire and by direct observations via the rapid upper limb assessment (RULA) to determine ergonomic risks. RULA is a validated tool for assessment of ergonomic risks. The mean age of the women was 30.2 (SD: 8.4) and the mean number of years of employment was 13.4 (SD: 5.5). The highest prevalence rates for the women’s musculoskeletal symptoms were in the trunk (62.5%), neck (50.5%), and shoulder (50.2%). Of the women, 65% had experienced musculoskeletal pain or discomfort over the last 6 months. Pain intensity of these symptoms was assessed with a visual analogue scale. The average pain intensity of the women was found to be 3.5 (SD: 2.8). Results of the RULA scores were found to be quite high. There were no employees who received RULA scores of 1–2, which indicates acceptable postures (all scores >5). The final RULA scores of 6.9 indicate that the participants’ postures at their work stations need to be investigated immediately.

Relevance to industry

This study based on the RULA method allowed to perform a rapid and quite correct evaluation tolls for SMOs. For this research population, the research findings provided fundamental data on the prevalence of musculoskeletal symptoms and ergonomic risks among Turkish female SMOs.     

Musculoskeletal disorder prevalence and psychosocial risk exposures by age and gender in a cohort of office based employees in two academic institutions

This study presents data on self-reported prevalence of Musculo-Skeletal Disorder (MSD) symptoms and psychosocial risk exposures by age and gender among a group of office based University workers who use their computers for at least 25% of their workday. Employees in two academic organisations received an invitation to participate in an on-line questionnaire. A total of n = 852 office workers participated in this study; yet respondents who were employed for greater than 12 months were only included in the study cohort. Furthermore, participants were only considered for further analysis if they spent 50% or more of their workday in their office, and of this time at least 50% was spent on computer work (n = 569). The study indicates that self-reported symptoms of MSDs for these workers were highest in the neck, shoulder and lower back. Neck, shoulder and back MSDs were higher for females than males, yet age differences within genders were not evident for these symptoms. For neck disorders, symptomatic individuals reported significantly higher levels of office work (p < 0.05) and PC usage (p < 0.005), and significantly lower levels of job content (p < 0.01), job demands (p < 0.05), and work environment (p < 0.05) compared to asymptomatic participants. For the shoulder, symptomatic individuals exposure levels were significantly higher for office work (p < 0.05) and PC usage (p < 0.05) and significantly lower for job content (p < 0.05) compared to asymptomatic individuals. There was evidence of important differences in the psychosocial exposures between age and genders, but associations between these differences and MSD symptoms were not present.Relevance to industryThis study presents prevalence data on age and gender differences in self-reported symptoms of MSDs and psychosocial risk exposures in a group of sedentary workers.     

Age-related differences in the initial usability of mobile device icons

Mobile devices offer much potential to support older adults (age 65+). However, older adults have been relatively slow to adopt mobile devices. Although much ongoing HCI research has examined usability problems to address this issue, little work has looked at whether existing graphical icons are harder to use for this population compared with younger adults. We conducted a qualitative exploratory study and a follow-up experimental study to determine which icon characteristics help initial icon usability for older adults. We found that our older participants did have more problems using existing mobile device icons, but that particular icon characteristics – semantically close meaning (i.e. natural, close link between depicted objects and associated function), familiar, labelled and concrete (i.e. those depicting real-world objects) – improved icon usability for them. We discuss how these findings can help icon designers to create mobile device icons that are more suited to the abilities and technology experience of older adults.     

Work posture,working conditions and musculoskeletal outcomes in agricultural workers

This study evaluated the working postures, working conditions and musculoskeletal outcomes among different agricultural workers in Iran. Data were collected using questionnaires and direct observations of posture (using the Rapid Upper Limb Assessment [RULA] method) from 377 farmers including 150 rice farmers, 122 vegetable growers, and 105 greenhouse workers. The overall prevalence of musculoskeletal symptoms, particularly in the low back (75.1%), knees (62.1%), upper back (61.55%), and neck (59.9%) was very high, and 72.6% of farmers experienced more than three locations of pain/discomfort. The mean RULA grand score of 6.7 highlighted that most farmers needed immediate investigation and changes in their working postures. Being female (neck pain), occupation (rice farmers – low back pain), number of years worked as an agricultural worker (neck and knee pain), prolonged daily working hours (upper back pain), job satisfaction (neck and low back pain), fast working (upper back pain), and working postures (neck, upper back, low back and knee pain) were independently associated with the presence of musculoskeletal symptoms. These findings emphasise the need for multiple component interventions to improve the working conditions of this population.     

Neck,shoulder and low back pain in secondary schoolchildren in relation to schoolbag carriage: Should the recommended weight limits be gender-specific?

The occurrence of neck, shoulder and low back complaints in relation to schoolbag carriage and other potential risk factors were investigated in a cross-sectional study of 586 Iranian schoolchildren aged 12–14 years. The average load carried by schoolchildren was 2.8 kg. Neck, shoulder and low back complaints during the preceding month were reported by 35.3%, 26.1% and 33% of the students, respectively. Gender was an independent factor predicting musculoskeletal symptoms in schoolchildren. Girls were more likely than boys to suffer from neck, shoulder and low back complaints, although there was no significant difference between genders in terms of schoolbag carriage variables. The findings suggest that the recommended weight limit for schoolbag carriage may need to differ between boys and girls. The associations between schoolbag variables and reported symptoms are also discussed. The results provide evidence that the current weight limit should consider a broader combination of factors that influence the use of schoolbags.     

Neck loads and posture exposure of helicopter pilots during simulated day and night flights

This study investigated neck loads and neck postures experienced by Canadian Forces (CF) helicopter pilots during routine simulator day and night flights. During the night flights pilots’ helmets were equipped with night vision goggles (NVG) which have been implicated in the increase of neck pain amongst pilots. Pilot’s postures were determined from video recordings of their flight missions to: (1) identify the neck postures assumed during day and night flight missions, and (2) determine the amount of biomechanical cervical spine loading experienced during these flights. Neck postures and peak and cumulative cervical kinetic loading were significant different (P < 0.05) between day and night. During night flights the percentage of work cycle spent in mildly flexed posture increased significantly from 43% during day flights to 74% during night flights. As well, cumulative reaction compression values significantly increased from 583 kN s to 694 kN s. The biomechanical results lend support to previous physiological investigations of NVG use and further justify the need for guidelines associated with NVG use.

Relevance to industry

The research highlights the biomechanical demands on the neck resulting from wearing a helmet with added weight from night vision equipment. The results have direct implication to military and commercial operators required to wear night vision equipment or added weight to the head.     

Association between numbers of long periods with sustained low-level trapezius muscle activity and neck pain

The purpose of this prospective cohort study was to evaluate relationships between sustained low-level muscle activity (SULMA) in the neck and pain after 1 year among machine operators of forest harvesters (n = 19), forwarders (n = 20) and forest researchers (n = 20). Surface electromyography of the right upper trapezius muscle was measured during one working day. Continuous muscle activity (SULMA periods) were analysed in predetermined time intervals. Neck pain was assessed by the Borg's category-ratio scale and the Standardized Nordic Questionnaire (dichotomised into pain duration ≤30 or >30 d). Harvesters reported significantly more pain than researchers. A higher number of long SULMA periods >8 min duration increased the risk of neck pain >30 d during the successive year (odds ratio 3.0, 95% CI 1.2–7.8). Perceived personal economy above average was associated with less pain, while other potential confounders or intermediate variables were not significant. Low-level trapezius muscle activity in periods longer than 8 min may constitute a risk for neck pain.     

Towards exposure limits for working postures and musculoskeletal symptoms – a prospective cohort study

Occupational postures are considered to be an important group of risk factors for musculoskeletal pain. However, the exposure-outcome association is not clear yet. Therefore, we aimed to determine the exposure-outcome association of working postures and musculoskeletal symptoms. Also, we aimed to establish exposure limits for working postures. In a prospective cohort study among 789 workers, intensity, frequency and duration of postures were assessed at baseline using observations. Musculoskeletal pain was assessed cross-sectionally and longitudinally and associations of postures and pain were addressed using logistic regression analyses. Cut-off points were estimated based on ROC-curve analyses. Associations were found for kneeling/crouching and low-back pain, neck flexion and rotation and neck pain, trunk flexion and low-back pain, and arm elevation and neck and shoulder pain. The results provide insight into exposure-outcome relations between working postures and musculoskeletal symptoms as well as evidence-based working posture exposure limits that can be used in future guidelines and risk assessment tools.

Practitioner Summary: Our study gives insight into exposure-outcome associations of working postures and musculoskeletal symptoms (kneeling/crouching and low-back pain, neck flexion/rotation and neck pain, trunk flexion and low-back pain, and arm elevation and neck and shoulder pain). Results furthermore deliver evidence-based postural exposure limits that can be used in guidelines and risk assessments.     

All-terrain vehicle use in agriculture: Exposure to whole body vibration and mechanical shock

Whole body vibration (WBV) and mechanical shock were measured in 12 New Zealand farmers during their daily use of all-terrain vehicles (ATVs). As per the International Organization for Standardization (ISO) guidelines for WBV exposure, frequencies between 0 and 100 Hz were recorded via a seat-pad tri-axial accelerometer during 20 min of ATV use. The farmers were also surveyed to estimate seasonal variation in daily ATV usage as well as 7-day and 12-month prevalence of spinal pain. Frequency-weighted vibration exposure and total riding time were calculated to determine the daily vibration dose value (VDV). The daily VDV of 16.6 m/s^1.75 was in excess of the 9.1 m/s^1.75 action limit set by ISO guidelines suggesting an increased risk of low back injury from such exposure. However, the mean shock factor R, representing cumulative adverse health effects, was 0.31 indicating that these farmers were not exposed to excessive doses of mechanical shock. Extrapolation of daily VDV data to estimated seasonal variations of farmers in ATV riding time demonstrated that all participants would exceed the ISO recommended maximum permissible limits during the spring lambing season, as compared to lower exposures calculated for summer, autumn and winter. Low back pain was the most commonly reported complaint for both 7 day (50%) and 12 month prevalence (67%), followed by the neck (17% and 42%) and the upper back (17% and 25%) respectively. The results demonstrate high levels of vibration exposure within New Zealand farmers and practical recommendations are needed to reduce their exposure to WBV.     

Risk of neck musculoskeletal disorders among males and females in lifting exertions

Work-related neck disorders are common among various occupational groups. Despite clear epidemiological evidence for the association of these disorders with forceful arm exertions, the effect of such exertions on the biomechanical behavior of the neck muscles is currently not well understood. In this study, the effect of lifting tasks on the biomechanical loading of neck muscles was investigated for males and females. Twenty-six participants (13 males and 13 females) performed bi-manual isometric lifting tasks at knuckle, elbow, shoulder, and overhead heights by exerting 25%, 50%, and 75% of their maximum strength. The activity of the cervical trapezius and sternocleidomastoid muscles was recorded bilaterally using surface electromyography. Higher activity of the cervical trapezius muscle (10% MVC–43% MVC) compared to the sternocleidomastoid muscle (4% MVC–18% MVC) was observed. Females tend to use the sternocleidomastoid muscle to a greater extent than males, whereas, higher cervical trapezius muscle activation was observed for males than females. The main effect of weight and height, and weight by height interaction on the activity of neck muscles was statistically significant (all p < 0.001). The results of this study demonstrate that the neck muscles play an active role during lifting activities and may influence development of musculoskeletal disorders due to resulting physiological changes.