Head forward flexion, lateral bending and viewing distance in smartphone users: A comparison between sitting and standing postures

Eyestrains among smartphone users while watching videos in Taipei MRT carriages: a comparison between sitting and standing postures

In MRT carriages, more passengers are watching videos on their smartphones during daily commutes, yet the impact of these viewing conditions on visual strain remains unexplored. This study examined eyestrain in 24 male and 24 female participants while watching videos on smartphones in two postures (sitting and standing) and over two durations (15 min and 30 min) in Taipei MRT carriages. We measured critical flicker fusion frequency (CFF) reduction, visual fatigue scale (VFS) scores, and viewing distance (VD) for each trial. Results revealed significant effects of sex, posture, and viewing duration on visual strain, with notable two-way interactions (sex × posture and posture × time) influencing most outcomes. Women showed greater CFF reduction while sitting compared to standing (3.47 Hz vs. 1.90 Hz, p < 0.001) and maintained shorter VDs while seated (25.5 cm vs. 34.3 cm, p < 0.001). However, they reported higher VFS scores when standing (8.94 vs. 4.60, p < 0.001), indicating increased discomfort while standing in the moving MRT carriage. Men exhibited higher CFF reduction (2.81 Hz) than women while standing (1.90 Hz) (p < 0.01), but this difference was not observed while sitting. Eyestrain indicators significantly worsened after 30 min of viewing compared to 15 min, with stronger effects on VFS scores and VDs. This finding supports the recommendation to take breaks after 20 min of smartphone use, even in MRT carriages. Although subjective eyestrain is not always recognized, watching videos on smartphones while seated can result in unexpectedly high levels of objective visual fatigue, indicated by CFF reduction. Our findings suggest that eyestrain patterns in MRT carriages differ from those reported in previous studies. Seated passengers, particularly females with shorter VD, may experience unrecognized eyestrain that could impact eye health, while standing passengers may face greater discomfort. These results highlight the need for increased awareness and preventive measures to mitigate eyestrain in digital public transportation environments.

Neck and shoulder strains under various head flexing positions while standing and sitting with and without back support for male and female smartphone users

This study recruited 30 young participants (15 men and 15 women) to examine the smartphone usage patterns in three postures (standing, supported sitting, and unsupported sitting) and at five head angle (HA) positions (0°-40°). Cervical erector spinae (CES) and upper trapezius (UTZ) muscle activity, neck flexion (NF), gaze angle (GA), viewing distance (VD), and discomfort scores were collected. Results showed that HA and posture almost affected all responses, while CES muscle activity, NF, and VD differed between sexes. Strain in the neck and shoulder region increased with HA increase. Particularly, when the HA exceeded 20°, the discomfort scores considerably increased. Unsupported sitting should be avoided during smartphone use because of relatively poor responses in all variables. However, both standing and supported sitting have their respective benefits. Sex-related differences were typically observed in the standing position, with women tending to have lower NF but higher CES muscle activity compared with men.Practitioner summary: Although smartphones have become daily necessities, the overall quantitative neck and shoulder strain of using smartphones in different postures is rarely evaluated. We suggest that maintaining the HA within 20° is recommended because of relatively low load on the neck and shoulders. An unsupported sitting should be avoided during smartphone use.

Gender differences in neck muscle activity during near-maximum forward head flexion while using smartphones with varied postures

Women frequently express heightened neck discomfort even though they exhibit smaller neck flexion (NF) during smartphone use. Differences in natural posture while using smartphones may result in varying muscle activation patterns between genders. However, no study focused on this issue. This study investigated the influence of gender on neck muscle activity and NF when using smartphones, ranging from slight (20°) to nearly maximal forward head flexion, across different postures. We analyzed smartphone usage patterns in 16 men and 16 women and examined these behaviors across different scenarios: standing, supported sitting, and unsupported sitting, at 20°, 30°, 40°, and the maximum head angles. During data collection, muscle activity was measured, expressed as a percentage of the maximum voluntary contraction (%MVC), in the cervical erector spinae (CES) and upper trapezius (UTZ), along with NF. Results show significant influences of gender, head angle, and posture on all measures, with notable interactions among these variables. Women displayed higher muscle activities in CES and UTZ, yet exhibited lesser NF, while using smartphones in both standing (12.3%MVC, 10.7% MVC, and 69.0°, respectively) and unsupported sitting (10.8%MVC, 12.3%MVC, and 71.8°, respectively) compared to men (standing: 9.5%MVC, 8.8%MVC, and 76.1°; unsupported sitting: 9.7%MVC, 10.8%MVC, and 76.1°). This study provides a potential rationale for gender-related disparities in injury outcomes, emphasizing that women experience higher neck and shoulder discomfort level, despite their smaller NF during smartphone use, as found in previous research. Additionally, the cervical flexion-relaxation phenomenon may occur when the head angle exceeded 40°. The near-maximum head angle during smartphone use might induce the cervical flexion-relaxation phenomenon, potentially aggravating neck issues. We recommend limiting smartphone usage postures that exceed the near-maximum head angle, as they are commonly adopted by individuals in the daily smartphone activities.

Perceived Discomfort, Neck Kinematics, and Muscular Activity During Smartphone Usage: A Comparative Study

OBJECTIVE

The present study aims to evaluate the effects of posture, task, and handgrip style on discomfort, neck kinematics, and concomitant muscular activity when using a smartphone (SP).

BACKGROUND

Along with the popularity of smartphones, musculoskeletal disorders have become prevalent among smartphone users. However, comprehensive aspects of discomfort, kinematics, and electromyographic responses across various conditions remain to be investigated.

METHOD

Twenty-four young smartphone users performed typing, video watching, and reading tasks while holding the smartphone both with one hand and with two hands while either sitting or standing. Neck kinematics and muscular activities were simultaneously recorded.

RESULTS

Working with SPs led to higher discomfort in the neck (p = 0.01), lower back (p = 0.01), and shoulder (p = 0.04) while sitting as compared to standing. Sitting was associated with greater neck flexion and more minor lateral bending for all tasks and grip styles (p < 0.05). Electromyographic analysis indicated significant differences between sitting and standing, with alterations being dependent on the test condition. Moreover, neck kinematics and muscular activities significantly differed based on the task nature, handgrip, and interactions.

CONCLUSION

This study highlights the risk of using smartphones in increased neck angle flexion and muscular activities fatigue. Thus, posture and handgrip should be considered while using SPs. As each test condition affects a specific dependent variable, a holistic approach is required to evaluate the responses of SP users' musculoskeletal systems.

APPLICATION

Results can be applied to develop guidelines for musculoskeletal disorders/discomfort prevention among SP users, especially with the rise of smartphone use during the COVID-19 pandemic.

Severity of slouched posture during smartphone use is associated with the musculoskeletal discomfort, daily usage, and school year among adolescents

Real-time measurement of the craniovertebral, thoracic kyphosis, and lumbar lordosis angles during natural and smartphone usage postures in sitting were analysed in a cohort of 560 adolescents using independent t-tests and Spearman's correlations between their reported musculoskeletal symptoms, daily device use and school year. Students with musculoskeletal symptoms (mean difference: 4.1-9.4°, p < .001) and in secondary schools (mean difference: 13.6-29.4°, p < .001) had a greater forward-head posture quantified by craniovertebral angle in both postures. Loss of lumbar lordosis was found in students spending ≥2 h/day on electronic devices (mean difference: 3.2°, p = .029) and those with musculoskeletal symptoms (mean difference: 5.4°, p = .001). Secondary school students exhibited a greater thoracic kyphosis when using smartphones (mean difference: 3.3°, p = .003). Findings suggest the urgent need for early and proactive intervention targeted to minimise the risk of developing musculoskeletal disorders related to intense device use for young adolescents.Practitioner Summary: Adolescents: (1) in higher school year had increased forward-head posture (FHP) and thoracic kyphosis; (2) with musculoskeletal symptoms had increased FHP and loss of lumbar lordosis, and; (3) with extended device use had a loss of lumbar lordosis. Early intervention targeting young adolescents promoting optimal posture and habit of device use is warranted.

TFOS Lifestyle: Impact of the digital environment on the ocular surface

Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as "the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing". Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not 'diagnostic' of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts).

The Reliability and Validity of the Turkish Version of Smartphone Impact Scale

The Smartphone Impact Scale (SIS) was originally developed in English to determine the cognitive, affective, social, and behavioral impacts of smartphones. This study aimed to translate and cross-culturally adapt the SIS instrument into Turkish and investigate its psychometric properties. Two hundred and sixty-four young and middle-aged adults (186 females) with a mean age of 36.24 years (SD = 14.93; range, 18-65 years) were included. For cross-cultural adaptation, two bi-lingual translators used the back-translation procedure. Within a 5-to-7-day period after the first assessment, the participants completed the Turkish version of SIS (SIS-T) to evaluate test-retest reliability. Cronbach's alpha (α) was used to assess internal consistency. The correlation between the Turkish version of the Smartphone Addiction Scale (SAS-T) and the Nottingham Health Profile was determined to check the validity. The SIS-T had a high-level internal consistency (α = 0.86) and test-retest reliability (ICC2,1 = 0.56 to 0.89 for subscales). The SIS-T subscales were correlated with the SAS-T (r = 0.31 to 0.66, p < 0.01), indicating a good concurrent validity. The results show that the SIS-T is semantically and linguistically adequate to determine smartphones' cognitive, affective, social, and behavioral impacts on young and middle-aged adults. Good internal validity and test-retest reliability of the SIS-T were defined to evaluate the impacts of smartphones among Turkish-speaking young and middle-aged adults.

Upper crossed syndrome in secondary school students: A mixed-method study

Objective

The study objectives were to identify the prevalence of upper crossed syndrome (UCS) and its associated factors in a population of Spanish adolescents, and to explore these associations through focus groups.

Methods

The study used a sequential explanatory mixed method design. The quantitative phase consisted of a cross-sectional study in which 45 students underwent photogrammetry measurements and evaluations with the Kiddo-KINDL and VISA-TEEN questionnaires. Subsequently, several focus groups were conducted to discuss the quantitative results.

Results

The results indicated a 37.8% prevalence of UCS, a 48.9% prevalence of forward head posture (FHP) and an 80% prevalence of forward shoulder posture (FSP). A positive FSP was indicated by an angle represented by the intersection of the line between the midpoint of the humerus and the spinous process of C7 of <52°. FSP was significantly higher in boys (mean [M] = 43.59, standard deviation [SD] = 6.9) than in girls (M = 47.98, SD = 6.33; p < 0.05). Boys showed significant moderate associations of FSP with body mass index (BMI) (r = -0.48, p < 0.05) and hygiene habits (r = -0.46, p < 0.05), and of FHP with worse use of technology (r = 0.53, p < 0.05). Those with UCS showed significant differences in school performance (M = 47.22, SD = 8.33, p < 0.05). Analysis of the qualitative results led to the identification of 33 codes and five categories.

Conclusions

UCS was associated with factors such as BMI, school performance, use of technology and physical activity. Correcting posture in adolescence was generally believed to be necessary. Physical exercise and postural health were considered highly important among adolescents.

The association between mobile phone use and neuromusculoskeletal complaints

BACKGROUND

Mobile phones have become an essential component in our life. There are many concerns about the effects of prolonged mobile phone use on the upper extremity.

OBJECTIVE

This research aims to investigate the effects of prolonged mobile phone use on the neuromusculoskeletal system of the upper extremity in young adults in Jordan.

METHODS

A total of 228 subjects (age = 20.7±1.27 years) participated in this study. A structured questionnaire was used to collect data on sociodemographic variables, mobile phone size, hand/finger used for typing, duration of use daily, and the presence of musculoskeletal pain/syndromes and their location.

RESULTS

Statistically significant relations (p < 0.05) were found between the prolonged use of mobile phones and self-reported pain in neck/upper back, hands, and symptoms of cubital syndrome; between smaller hand-to-phone ratio and pain in neck/upper back and shoulders with the higher frequency of pain in females. Females and subjects with a smaller hand-to-phone ratio tend to use two hands (p < 0.05).

CONCLUSION

The results show an association between mobile phone use and self-reported pain. This study provides guidance for mobile phone manufacturers and regulatory agencies on the potential effects, the need for awareness programs that alert to musculoskeletal complaints, choosing the appropriate mobile phone, and changing using habits. Further investigations on a larger sample with quantitative measures on the kinematics and muscular activities are necessary to generalize and better interpret the results.

Relationship between musculoskeletal discomfort and cell phone use among young adults: A cross-sectional survey

BACKGROUND

Cell phone usage is highly prevalent among young adults. They are used for multiple purposes including communication, studies, social networking and entertainment. However, its excessive usage has been associated with adverse health outcomes.

OBJECTIVE

The objective was to find the association of cell phone usage with musculoskeletal discomfort (MSD) and its associated factors.

METHODS

A cross-sectional study was conducted on young adult students from a low-middle income country over a period of 3 months from December 2018 to February 2019. A structured questionnaire based on the Disabilities of the Arm, Shoulder and Hand (QuickDASH scoring) was used to record the musculoskeletal discomfort.

RESULTS

Out of 803 questionnaires, data of 754 (94%) were entered and the remaining questionnaires (n = 49) were discarded due to incomplete answers. The mean age was 20.83 (1.62) years. In our study, there were 194 (25.7%) males and 560 (74.3%) female participants. Neck and shoulder were the most frequently affected regions. A significant difference in QuickDASH score was observed between genders (p-value p ≤ 0.001). Left-handed individuals scored significantly higher on QuickDASH score compared to right-handed individuals (p < 0.05). Increased musculoskeletal discomfort was reported by individuals with daily cell phone use of more than four hours (p < 0.05). A positive significant correlation was found between continuous one hour cell-phone use and higher mean QuickDASH scores (correlation coefficient 0.124, p value 0.001). Shorter eye-to-screen distance was significantly associated with MSD (p < 0.05).

CONCLUSION

Musculoskeletal discomfort is associated with the female gender, duration of cell phone use and a small eye-to-screen distance.

Impact of Digital Device Use on Neck and Low Back Pain Intensity among Nursing Students at a Saudi Government University: A Cross-Sectional Study

As digital technology and online activities have become more widely accessible over the past few years, information and communication technology have grown in importance in all students' lives. Most of them routinely use digital devices for a range of activities, primarily for online learning, activities, assignments, conversing, and Internet browsing. This study elucidated the relationship between neck and low back pain intensity and the use of digital devices among Saudi nursing students. A cross-sectional descriptive exploratory research design was applied using a convenience sample of 120 nursing students enrolled in an undergraduate nursing program at a Saudi government university located in Riyadh, the capital city of Saudi Arabia. A valid and reliable self-administered survey was employed. Data about sociodemographic characteristics, the Neck Disability Index and the Roland-Morris Disability Questionnaire were collected. The participants reported 9.1 ± 4.6 study hours on average per week. A total of 82.5% of them do not receive enough exercise, and 87.5% indicated daily use of digital devices. Around half (54.2%) of participants reported having neck pain of a mild intensity. About 60% of the participants regularly shift positions to rest their backs, 39.2% are only able to stand for limited periods due to back issues, and 39.2% expressed concern for others about what might happen to their health. Although there was an association between neck pain intensity and the age or gender of all research participants, there was a significant association between neck pain severity and marital status (χ² = 15.226, p = 0.019). Our findings suggest that nursing students should maintain neutral neck and back postures on a regular basis to reduce pain, which could be attributed to extensive reading on digital devices.

Physical activity, sitting time, neck disability and posture in workers using visual display terminals (VDT)

BACKGROUND

Musculoskeletal pain represents a major public health problem. Workers who use visual display terminals (VDT) have suffered an increase in neck pain in recent decades.

OBJECTIVE

The aim of this study was to analyze the relationship between physical activity (PA), sitting time, posture, and neck disability in a population of employed adults who use a computer at work.

METHODS

In this descriptive-correlational study, 88 workers with a mean age of 48.31 years participated. All of the participants filled out the Self-Report Habit Index (SRHI), International Physical Activity Questionnaire (IPAQ), and Neck Disability Index (NDI). The postural situation was also assessed with Posture Assessment Software (PAS/SAPO).

RESULTS

A significant and inverse relationship was observed between the habit of PA practice and the Body Mass Index (BMI). A total of 59.1% of the participants have a moderate PA index. There was a statistically significant relationship between the NDI and the time that workers spend sitting in a workday. A significance level of p≤0.05 was established for all the statistical analyses.

CONCLUSION

The increase in sitting time produces an increase in neck disability among workers and there are no significant differences between the level of PA and the cervical angles analyzed. The promotion of leisure-time PA and the reduction of prolonged uninterrupted sitting time at work could be one of the means to reduce musculoskeletal morbidity in the working population.