Influence of smartphone use styles on typing performance and biomechanical exposure

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.

Upper Limb Function Recovery by Combined Repetitive Transcranial Magnetic Stimulation and Occupational Therapy in Patients with Chronic Stroke According to Paralysis Severity

Repetitive transcranial magnetic stimulation (rTMS) with intensive occupational therapy improves upper limb motor paralysis and activities of daily living after stroke; however, the degree of improvement according to paralysis severity remains unverified. Target activities of daily living using upper limb functions can be established by predicting the amount of change after treatment for each paralysis severity level to further aid practice planning. We estimated post-treatment score changes for each severity level of motor paralysis (no, poor, limited, notable, and full), stratified according to Action Research Arm Test (ARAT) scores before combined rTMS and intensive occupational therapy. Motor paralysis severity was the fixed factor for the analysis of covariance; the delta (post-pre) of the scores was the dependent variable. Ordinal logistic regression analysis was used to compare changes in ARAT subscores according to paralysis severity before treatment. We implemented a longitudinal, prospective, interventional, uncontrolled, and multicenter cohort design and analyzed a dataset of 907 patients with stroke hemiplegia. The largest treatment-related changes were observed in the Limited recovery group for upper limb motor paralysis and the Full recovery group for quality-of-life activities using the paralyzed upper limb. These results will help predict treatment effects and determine exercises and goal movements for occupational therapy after rTMS.

Typing with mobile devices: A comparison of upper limb and shoulder muscle activities, typing performance and perceived workload under varied body postures, typing styles and device types

This study aimed to examine the effects of body posture, typing style and device type on upper limb and shoulder muscle activities, typing performance and perceived workload while typing with mobile devices. Participants were asked to type with two mobile devices (i.e., a tablet and a smartphone) under three postures and in two typing styles. Muscle activity was recorded for four upper limb and shoulder muscles on both sides with surface electromyography. Results showed that body posture and typing style yielded significant effects on tying performance, perceived workload, and muscle activities in the forearm, upper arm and shoulder. Typing with a tablet was more accurate and had greater muscle activities in the upper arm and forearm on both sides than typing with a smartphone. The findings may be useful in developing evidence-based guidelines for the wise use of mobile devices and for the prevention of risks for musculoskeletal disorders.

Fatigue due to smartphone use? Investigating research trends and methods for analysing fatigue caused by extensive smartphone usage: A review

BACKGROUND: The easy accessibility of smartphones has led to a fivefold increase in their use. People use smartphones almost anywhere, including during travelling and studying. During the global COVID-19 pandemic, the average smartphone screen time has increased from 2.25 to 4.8 hours per day. In India, smartphone usage increased by 68%, and the average screen time increased from 2.42 to 6.9 hours. This dependency on smartphones has led to smartphone addiction. Inappropriate postures during the prolonged use of smartphones can exert adverse effects such as musculoskeletal disorders, digital eye strain, loss of focus and attention. OBJECTIVES: This study was undertaken to understand the effects of prolonged smartphone utilisation and explored fatigue measurement techniques. METHODS: A total of 130 studies examining the effects of smartphone utilisation published in the previous 10 years were identified from the following databases: IEEE, Science Direct, PubMed, PubMed Central, and Google Scholar are reviewed. This study was conducted from September 2019 to January 2021. RESULTS: One in every four adolescents were prone to smartphone addiction, which causes poor mental health. Moreover, India’s research on the effects of excessive smartphone usage is limited. CONCLUSIONS: Studies are required to establish the correlation between fatigue levels and smartphone usage patterns.

Differences in neck muscle activity according to lying positions using a smartphone

BACKGROUND

Due to the extended use of smartphones, people spend a lot of time on these devices while lying down.

OBJECTIVE

The purpose of the present study was to compare the differences in neck muscle activity of participants while they watched videos on a smartphone in four different lying positions (supine (SUP), prone on elbows (PE), side lying (SIDE), and 45∘ head turn while side lying (45-SIDE)).

METHODS

Twenty-three healthy volunteers (22.4 ± 1.7 years) were enrolled in this study. We assessed the activities of their right and left sternocleidomastoid (SCM), anterior scalene, cervical erector spinae (CES), and upper trapezius (UT) muscles while they watched videos on a smartphone in four different lying positions.

RESULTS

The right and left SCM and CES had significantly different muscle activities depending on the lying positions. The SCM activity had a significantly greater asymmetry in the 45-SIDE position, while the CES activity had a significantly greater asymmetry in the SIDE and 45-SIDE positions. Moreover, the UT activity had a significantly greater asymmetry in the SUP, PE, and SIDE positions.

CONCLUSIONS

Neck muscle activity and asymmetry were the lowest in the SUP position relative to the other positions. Therefore, lying down in the SUP position may minimize neck muscle activation while using a smartphone.

Acute Pain, Neck Extensor Endurance, and Kinematic Changes Resulting from Sustained Neck Flexion during Smartphone Use

OCCUPATIONAL APPLICATIONSThe National Occupational Research Agenda for Musculoskeletal Health in the United States identified that with the changing nature of the traditional office environment, mobile devices are now frequently used for longer durations, warranting research on the impacts of mobile computing on musculoskeletal health. A recent study of office workers showed that those with "smartphone overuse" were six times more likely to report neck pain. Working in pain may also result in withdrawal and less proactive extra-role behaviors at work (such as making recommendations at work and willing to help colleagues). We found that 30-minutes of mobile device use resulted in pain reporting in the neck and upper back when the device was used with neck flexion. This musculoskeletal pain could lead to acute concerns during the workday and long-term problems over time.

Neck pain associated with smartphone overuse: cross-sectional report of a cohort study among office workers

PURPOSE

The aim of the current study was to investigate the extent of smartphone use, possible correlation with neck pain and/or psychological impairment in office workers.

METHOD

A convenience sample of 1,602 office workers who were using smartphone for prolonged periods (≥ 4 years) participated in a cross-sectional report of a cohort study, assessing demographic, abnormal symptoms of pain in the neck, physical activity, and psychological behavior characteristics. Participants were assessed using a short version of the Smartphone Addiction Scale (SAS-SV), Depression, Anxiety and Stress Scales (DASS-42) questionnaire, as well as International Physical Activity Questionnaire-Short Form (IPAQ-SF). Multiple logistic regression model was conducted to evaluate the adjusted effect of smartphone overuse on nuchal symptoms.

RESULTS

The prevalence of neck pain among the office workers was 30.1%. Significantly more female (33.3% vs. 24.5%) and younger (42.2 vs. 43.2 years) employees reported to have neck pain. Overall in 326 (20.3%, 95% CI: 18.4%-22.4%) of studied subjects had, SAS score ≥ 31 and ≥ 33 for male and females, respectively, and so smartphone overuse (SO) was diagnosed. The results of multiple logistic regression model revealed that those with SO were approximately 6 times more likely to have neck pain (95% CI: 4.44-8.09, P < 0.001).

CONCLUSIONS

Smartphone overuse in office workers significantly increases the chance of neck pain by 6 times. Hence SO has been associated with, not only somatic complaints, but also psychological distress such as anxiety, stress, and depression. This may necessitate adherence to neck-school, when smartphone use is associated with neck pain.

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

BACKGROUND

Smartphones (SPs) are widely used by people of all age groups and genders. Users spend many hours per day on the SPs for different purposes, which imposes significant stress on their musculoskeletal system.

OBJECTIVES

This study explored head forward flexion, lateral bending angle, and viewing distance while working with a SP in sitting/standing postures and one-handed/two-handed grips. The users' performance as well as pain development were also investigated.

METHODS

Participants answered a questionnaire on pain experience before and after SP usage. Neck kinematics of 20 SP users were monitored by a motion analysis system while doing three tasks (typing, video watching, and reading) in sitting and standing postures. Performance was evaluated by number of typed words, amount of errors in typing, and total read words.

RESULTS

The results indicated a significant increase in pain complaints in neck and upper limbs after test completion. Working with SPs in sitting and standing postures were, respectively, associated with greater head forward flexion for watching and viewing distance for two-handed typing tasks. Higher left lateral bending values were measured for one-handed watching and reading tasks in standing posture. The performance measures were superior for two-handed grips in all conditions.

CONCLUSIONS

Overall, using SPs in sitting posture creates greater head forward flexion and lower lateral bending angles in all tasks and grip types. The findings of this study can be used to provide recommendations for SP users.

Modulation in Elastic Properties of Upper Trapezius with Varying Neck Angle

Background

Neck and shoulder complaints caused by poor posture may influence upper trapezius stiffness. The relationship between the shear elastic modulus of the upper trapezius and cervical flexion angles is unknown. Therefore, it is essential to assess upper trapezius stiffness during cervical flexion. The objectives of this study were to (1) determine the intra- and interoperator reliabilities of evaluating upper trapezius stiffness and calculate the minimal detectable change (MDC); (2) examine the elastic modulus alterations of the upper trapezius during cervical flexion; and (3) explore the difference of upper trapezius stiffness between the dominant and nondominant sides.

Methods

Twenty healthy male participants were recruited in this study. The shear modulus of the upper trapezius was evaluated by two independent investigators using shear wave elastography (SWE) during cervical flexion at 0° and 50°.

Findings

The intraoperator (intraclass correlation coefficient (ICC) = 0.85–0.86) and interoperator (ICC = 0.94–0.98) reliabilities for measuring the shear elastic modulus of the upper trapezius during the cervical flexion ranged from good to excellent. An increase of 35.58% in upper trapezius stiffness was found at 0° to 50° of cervical flexion, and the MDC was 7.04 kPa. In addition, a significant difference was obtained in the elastic modulus of the upper trapezius muscle between the dominant and nondominant sides (P < 0.05).

Conclusions

Our findings revealed that SWE could quantify the elastic modulus of the upper trapezius and monitor its changes. Therefore, further studies are required to delineate the modulation in upper trapezius muscle stiffness among subjects with neck and shoulder pain.

Armrests and back support reduced biomechanical loading in the neck and upper extremities during mobile phone use

Mobile phone use is known to be associated with musculoskeletal pain in the neck and upper extremities because of related physical risk factors, including awkward postures. A chair that provides adequate support (armrests and back support) may reduce biomechanical loading in the neck and shoulder regions. Therefore, we conducted a repeated-measures laboratory study with 20 participants (23 ± 1.9 years; 10 males) to determine whether armrests and back support during mobile phone use reduced head/neck flexion, gravitational moment, and muscle activity in the neck and shoulder regions. The results showed that the chair support (armrests and back support) reduced head/neck flexion (p < 0.001), gravitational moment (p < 0.001), and muscle activity (p < 0.01) in the neck and shoulder regions significantly compared to no chair support. These results indicate that a chair with adequate support can be an effective intervention to reduce the biomechanical exposures and associated muscular pain in the neck and shoulders during mobile phone use.

Investigation of force, contact area and dwell time in finger-tapping tasks on membrane touch interface

This study aimed to determine the touch characteristics during tapping tasks on membrane touch interface and investigate the effects of posture and gender on touch characteristics variables. One hundred participants tapped digits displayed on a membrane touch interface on sitting and standing positions using all fingers of the dominant hand. Touch characteristics measures included average force, contact area and dwell time. Across fingers and postures, males exerted larger force and contact area than females, but similar dwell time. Across genders and postures, thumb exerted the largest force and the force of the other four fingers showed no significant difference. The contact area of the thumb was the largest, whereas that of the little finger was the smallest; the dwell time of the thumb was the longest, whereas that of the middle finger was the shortest. Relationships among finger sizes, gender, posture and touch characteristics were proposed. The findings helped direct membrane touch interface design for digital and numerical control products from hardware and software perspectives. Practitioner Summary: This study measured force, contact area and dwell time in tapping tasks on membrane touch interface and examined effects of gender and posture on force, contact area and dwell time. The findings will direct membrane touch interface design for digital and numerical control products from hardware and software perspectives. Abbreviations: M: mean; SD: standard deviation; ISO: International Organization for Standardization; LCD: liquid crystal display; ANOVA: analysis of variance; ANSI: American National Standards Institute; HFES: Human Factors and Ergonomics Society.

Texting with touchscreen and keypad phones - A comparison of thumb kinematics, upper limb muscle activity, exertion, discomfort, and performance

This study aimed to compare thumb kinematics and upper limb muscle activity, and the influence of hand size, when texting on a keypad smartphone and a touchscreen smartphone. Furthermore, the study compared exertion, discomfort, and performance when texting on the two phones. The thumb kinematics were tracked using a 3D motion analysis system and muscle activity was registered in six upper limb muscles using surface electromyography in 19 participants. When texting on the touchscreen phone compared to the keypad phone thumb flexion (p = 0.008) and flexion/extension range of motion were smaller (p = 0.02), the thumb was on average less internally rotated (p = 0.02), and activity (50th and 90th percentile) of the thumb and forearm muscles was lower (p ≤ 0.05). The differences in thumb flexion were found only in the group with shorter hands and the differences in muscle activity was found only in the group with longer hands. These findings suggest there are differences in risks for developing musculoskeletal disorders during smartphone use with different key activation mechanisms and different hand sizes.

Tablet form factors and swipe gesture designs affect thumb biomechanics and performance during two-handed use

Tablet computers' hardware and software designs may affect upper extremity muscle activity and postures. This study investigated the hypothesis that forearm muscle activity as well as wrist and thumb postures differ during simple gestures across different tablet form factors and touchscreen locations. Sixteen adult (8 female, 8 male) participants completed 320 tablet gestures across four swipe locations, with various tablet sizes (8″ and 10"), tablet orientations (portrait and landscape), swipe orientations (vertical and horizontal), and swipe directions (medial and radial). Three-dimensional motion analysis and surface electromyography measured wrist and thumb postures and forearm muscle activity, respectively. Postures and muscle activity varied significantly across the four swipe locations (p < .0001). Overall, swipe location closest to the palm allowed users to swipe with a more neutral thumb and wrist posture and required less forearm muscle activity. Greater thumb extension and abduction along with greater wrist extension and ulnar deviation was required to reach the target as the target moved farther from the palm. Extensor Carpi Radialis, Extensor Carpi Ulnaris, Flexor Carpi Ulnaris, Extensor Policis Brevis, and Abductor Pollicis Longus muscle activity also increased significantly with greater thumb reach (p < 001). Larger tablet size induced greater Extensor Carpi Radialis, Extensor Carpi Ulnaris, Flexor Carpi Ulnaris, Flexor Carpi Radialis, and Abductor Pollicis Longus muscle activity (p < .0001). The study results demonstrate the importance of swipe locations and suggest that the tablet interface design can be improved to induce more neutral thumb and wrist posture along with lower forearm muscle load.

The associations of mobile touch screen device use with musculoskeletal symptoms and exposures: A systematic review

BACKGROUND

The use of mobile touch screen devices (MTSDs) has increased rapidly over the last decade, and there are concerns that their use may have negative musculoskeletal consequences; yet evidence on the association of MTSD use with musculoskeletal symptoms and exposures is currently dispersed. The aim of this study was to systematically review available literature on musculoskeletal symptoms and exposures associated with MTSD use. The synthesised information may facilitate wise use of MTSDs and may identify areas in need of further research.

METHODS

EMBASE, Medline, Scopus, PsycINFO and Proquest electronic databases were searched for articles published up to June 2016, using keywords describing MTSD, musculoskeletal symptoms (e.g. pain, discomfort) and musculoskeletal exposures (e.g. posture, muscle activity). Two reviewers independently screened the articles, extracted relevant data and assessed methodological quality of included studies. Due to heterogeneity in the studies, a meta-analysis was not possible and a structured narrative synthesis of the findings was undertaken.

RESULTS

A total of 9,908 articles were screened for eligibility with 45 articles finally included for review. Included articles were of cross-sectional, case-control or experimental laboratory study designs. No longitudinal studies were identified. Findings were presented and discussed in terms of the amount, features, tasks and positions of MTSD use and its association with musculoskeletal symptoms and musculoskeletal exposures.

CONCLUSIONS

There is limited evidence that MTSD use, and various aspects of its use (i.e. amount of usage, features, tasks and positions) are associated with musculoskeletal symptoms and exposures. This is due to mainly low quality experimental and case-control laboratory studies, with few cross-sectional and no longitudinal studies. Further research is warranted in order to develop guidelines for wise use of MTSDs.

Effects of electronic device overuse by university students in relation to clinical status and anatomical variations of the median nerve and transverse carpal ligament

INTRODUCTION

This study investigates the results of a questionnaire, provocative tests, and ultrasonographic measurements of carpal tunnel morphological parameters in intensive and nonintensive electronic device users.

METHODS

Forty-eight university students (equal numbers of intensive and nonintensive users, ≥5 h/day and <5 h/day of electronic device usage, respectively) were randomly selected after questionnaire responses were received and evaluated clinically and by ultrasonography. All participants were right-handed.

RESULTS

Intensive users had significantly more positive results in Phalen's and Durkan's tests and reported more wrist/hand pain compared with nonintensive users (P < 0.05). Intensive users also had significantly larger median nerve cross-sectional areas, flattening ratios, and perimeters as well as greater bowing of the transverse carpal ligament compared with nonintensive users (P < 0.05).

DISCUSSION

Overuse of electronic devices may adversely affect the median nerve within the carpal tunnel and the transverse carpal ligament, resulting in numbness, tingling, and pain in the hand. Caution may be warranted when using handheld electronic devices. Muscle Nerve 56: 873-880, 2017.

Mobile Phone Use Behaviors and Postures on Public Transportation Systems

Mobile phones are common in our daily life, but the users’ preferences for postures or screen operating styles have not been studied. This was a cross-sectional and observational study. We randomly sampled passengers who used mobile phones on the Mass Rapid Transit (MRT) system in metropolitan Taipei. A checklist was used to observe their body postures and screen operating styles while sitting or standing. As a result, 1,230 subjects from 400 trips were observed. Overall, of all the passengers who were sitting, 41% of them were using mobile phones. The majority of the tasks involved browsing (84%) with their phones in a portrait orientation (93%). Different-hand holding/operating was the most commonly used operating style while sitting (46%) and same-hand holding/operating was the most common while standing (46%). The distribution of screen operating styles was significantly different for those sitting than for those standing and for different genders and age groups. The most frequently observed postures while sitting were having one’s trunk against a backrest, feet on the floor and with or without an arm supported (58%). As for the users who were standing, the both- and different-hands groups had a high proportion of arms unsupported, feet on the floor and either their trunk supported or not. In contrast, the same-hand group tended to have their trunk unsupported, were holding a pole or handstrap and had both feet on floor. Further studies are warranted to characterize the ergonomic exposure of these commonly used postures and operating styles, and our results will help guide the selection of experimental conditions for laboratory settings.