Thumb joint movement and muscular activity during mobile phone texting - A methodological study

Impact of Nomophobia on Musculoskeletal Problems in the Upper Extremity among Adults: Implications for Occupational Therapy

Nomophobia (NO MObile PHone Phobia) is a psychological condition in which people are anxious of being cut off from their mobile phones and been associated with adverse consequences to physical and psychosocial health. The objective of this study was to measure the impact of nomophobia on musculoskeletal problems in the upper extremity among adults. The Nomophobia scale (NMP-Q) was used to measure addiction to smartphone use among 5,087 Middle Eastern adults. A snowball sampling approach was used to recruit the participants between March and June 2021. Results showed that nomophobia was evident in 1,119 participants (22%) with a mean NMP-Q score of 114.1 (SD 11.1). A total of 3,396 upper extremity symptoms were reported among our participants. The binomial logistic regression showed that NMP-Q score is a significant predictor of symptoms to the thumb only (β = 0.01, p = .026). This study has provided evidence of the negative physical consequences of addiction to smartphone use. Participants with thumb-related symptoms were more prone to sustain other concurrent upper extremity symptoms, probably due to their maladaptive habits of using the phone. Thus, it is important to increase awareness about the risks associated with the use of smartphones. Implications for occupational therapy are presented.

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.

A Region-Based Statistical Shape Modeling on the First Trapezoid-Metacarpal

A statistical shape model (SSM) based analysis was conducted in our study. We indicated the morphological differences of the first trapezoid-metacarpal (TMC) bone between the region-based statistical shape model (rSSM) and the nonregion-based statistical shape model (nrSSM). We aimed to characterize more specific and accurate variation results to detect and prevent osteoarthritis in an early way. CT image data of TMC from 31 healthy volunteers were simulated with 3D models. A training set of models was analyzed with principal component analysis, with both then- rSSM and rSSM. The region was identified automatically with Gaussian curvature analysis. We found four dominant shape variations from both nrSSM and rSSM. The rSSM showed more variations with fewer components compared with nrSSM. The first principal component revealed the size variation as the biggest component. A significant difference was presented in the second and the fourth principal component from rSSM, showing the torsion of the distal head of the first metacarpal which may increase the risk of osteoarthritis.

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.

Problematic Smartphone Use: Prevalence and Associated Factors Among Health Sciences Students in Saudi Arabia

Excessive smartphone use leads to several physical and psychological disorders, particularly among young adults. This study aimed to investigate the prevalence and the associated factors of problematic smartphone use (PSU) among health sciences students in Jeddah, Saudi Arabia. During the 2019 academic year, a cross-sectional analytic study randomly recruited 408 health sciences students (67.5% were females), with a mean age of 20.5 ± 1.42. Data on sociodemographic and health profiles, smartphone usage patterns, and overuse symptoms were collected for each participant. The Smartphone Addiction Scale-Short Version (SAS-SV) and Generalized Anxiety Disorder 7-item (GAD-7) scale were used to assess PSU and anxiety levels. PSU was detected in 66.9% of the study participants. The prevalence is high among both females and males (69.5 and 61.7%, respectively). PSU was found to be associated with more years of use and frequent smartphone upgrading (aOR = 2.11, 95% CI: 1.12, 3.97) and (aOR = 1.69, 95% CI: 1.08, 2.65), respectively (p = 0.021 and 0.021, respectively). Participants with moderate and severe anxiety levels were found to be more likely to have PSU (aOR = 2.22, 95% CI: 1.21, 4.05) and (aOR = 5.97, 95% CI: 2.41, 14.78), respectively. (p = 0.010 and < 0.001, respectively). PSU is an emerging problem among health sciences students in Saudi Arabia with a high prevalence in both genders. Longer years of use, more frequent smartphone upgrades, and higher anxiety levels are associated with PSU among health sciences students. Special health education and psychological support programs are recommended to guide and support future healthcare providers against the consequences of PSU.

Mobile phone usage among Nigerians: Risk factors for musculoskeletal injuries and preventive strategies

AIMS

The increase in the usage of hand-held devices (HHDs) and smartphones (SPs), especially in Nigeria has resulted in an upsurge of musculoskeletal complaints. The aim of this study was to determine the incidence and risk factors for musculoskeletal injuries due to mobile phone usage among Nigerians and the preventive strategies.

MATERIALS AND METHODS

This study involved 630 male and female participants above 18 years old who were purposively recruited across designated study centres in public places. The instrument used was a questionnaire specifically designed to suit the Nigerian culture and environment and developed from previously validated questionnaires. Data were exported to Statistical Computing Programming R version 4.0.5 for analysis and Chi-square was used to compare the characteristics of those who experienced injury using SPs/HHDS and those who did not. Independent variables with a 95% confidence level and P < 0.05 in the multivariate model were considered statistically significant.

RESULTS

The most common daily use of SPs/HHDS by the participants was phone calls (98.4%) followed closely by social networking (96.0%) while the occupation and educational level of the participants had statistically significant (P < 0.05) impact on musculoskeletal injuries. The type of mobile device and the time spent using these devices were also significant (P < 0.05) risk factors for injuries. Some self-treatment strategies adopted by the participants were all significantly (P < 0.05) associated with reduction of musculoskeletal discomfort.

CONCLUSION

The occupation, educational level, the types of mobile devices and time spent using the devices were risk factors for musculoskeletal injuries.

Sensoring the Neck: Classifying Movements and Actions with a Neck-Mounted Wearable Device

Sensor technology that captures information from a user's neck region can enable a range of new possibilities, including less intrusive mobile software interfaces. In this work, we investigate the feasibility of using a single inexpensive flex sensor mounted at the neck to capture information about head gestures, about mouth movements, and about the presence of audible speech. Different sensor sizes and various sensor positions on the neck are experimentally evaluated. With data collected from experiments performed on the finalized prototype, a classification accuracy of 91% in differentiating common head gestures, a classification accuracy of 63% in differentiating mouth movements, and a classification accuracy of 83% in speech detection are achieved.

Diagnosis and Treatment of Carpometacarpal Instability

Hypermobility of the first CMC joint may adversely affect hand function and may lead to osteoarthritis later in life. It presents more commonly in younger women with generalized joint hypermobility or postmenopausal women with early stages of arthritis. It may follow trauma and deletive surgical interventions. Clinically, joint subluxation manifests with a prominent and unstable thumb base, and is radiographically confirmed by stress views. A variety of ligament reconstruction techniques are available to stabilize the CMC joint including open ligament reconstruction with or without temporary Kirschner-wire fixation, arthroscopic debridement with capsular shrinkage, metacarpal extension osteotomy, internal proprietary anchors, and arthrodesis.

Assessment of the Effect of Smartphone Usage on the Range of Motion and Fatigability of the Joints and Muscles of the Thumb Among Users: A Cross-Sectional Study in Central India

Introduction

The ability of adaptation is unique to humankind. Technology advances have introduced many appliances that increasingly are smaller in size and handheld. These devices on prolonged usage affect the thumb joint complex, and this study was therefore designed to assess any changes in the movement of the thumb joint complex and fatigability secondary to the increasing usage of smartphones in different orientations in the Central Indian population.

Materials and methods

An analytical cross-sectional study was performed to assess changes in the ranges of motion (ROM) of the thumb joint complex with a sample size of 137 selected nonrandomly and categorized on the basis of the orientation of smartphone usage by physical goniometer and a standardized questionnaire to assess fatigability.

Results

Most movements of the thumb joint complex corresponded to the existing standard values. The study found significant changes in the movement of passive flexion of the left metacarpophalangeal (MCP) joint and borderline significant modifications in the active extension of the left interphalangeal (IP) joint, passive extension of the left interphalangeal joint, and passive flexion of the left carpometacarpal (CMC) joint among the groups of participants. The Borg CR10 value of fatigue was “one,” indicative of no excessive fatigue after smartphone usage.

Conclusion

There are no significant changes in the ranges of motion of the joint complex of the thumb in mobile phone users over a period of time. The orientations and the increased duration of usage also did not cause any fatigue in the muscles of the thumb.

Weaknesses of research methodologies on musculoskeletal disorders associated with mobile touch-screen devices

The objective of the currently study is to point out the weaknesses of some recent researches, which were done about the effects or symptoms of using Touch Screen Mobile Devices on the human musculoskeletal system. In this article, we reviewed the research processes performed in recent 26 randomly selected papers about musculoskeletal disorder to clarify the common weaknesses of these published articles. The electronic database search and reference search were conducted in four different databases: Medline, PubMed, Web of Science, and Scopus. We noticed that none of the reviewed papers had performed the experimental design phase of a scientific research. Additionally they had not validated the assumptions of the statistical methods used in their researches. Therefore, their findings are doubtful. In this article, we proposed practical outlines for a reliable experimental research.

Spinal and Pelvic Alignment of Sitting Posture Associated with Smartphone Use in Adolescents with Low Back Pain

This study aimed to assess the association between smartphone use in the sitting posture and changes in thoracolumbar kyphosis, lumbar lordosis, and pelvic asymmetry in adolescents with low back pain (LBP). Twenty-five adolescents with LBP and 25 healthy adolescents participated in this study. They were instructed to sit on a height-adjustable chair with their hips and knees bent at 90° for 30 min in their usual sitting postures. Thoracolumbar kyphosis, lumbar lordosis, and pelvic asymmetry were measured using a three-dimensional motion capture system. Thoracolumbar kyphosis and lumbar lordosis increased after 30 min of sitting compared to the baseline. In both groups, thoracic kyphosis and lumbar lordosis angle increased with increasing sitting time. Compared to healthy adolescents, adolescents with LBP presented greater thoracolumbar kyphosis and lumbar lordosis after prolonged sitting. Pelvic asymmetry showed no significant difference between the sitting time and groups. Using a smartphone during prolonged sitting may lead to a slumped posture; these associations were more pronounced in adolescents with LBP.

Addiction of smartphones and related finger deformities: A case report

Widespread and excessive use of smartphones is very common, and its overuse is associated with several health-related conditions. A 58-year-old man presented with a spontaneous swan-neck deformity of the third digit. On his physical examination, full passive range of motion of the finger was achieved, while active range of motion was limited due to pain. Laboratory test results were normal. Ultrasonographic imaging demonstrated digital extensor tenosynovitis of the second, third, fourth, and fifth digits. Plain radiographs of bilateral hands were normal. Magnetic resonance imaging of the affected hand revealed no mass lesion. He attended to the hand rehabilitation program. At the end of the program, his pain decreased, and he was easily able to do the finger range of motion exercises. In conclusion, smartphone addiction has an adverse influence on hand function and pinch strength. Youngsters should be aware of the harmful effects which may result from smartphone overuse.

Excessive Smartphone Use and Self-Esteem Among Adults With Internet Gaming Disorder: Quantitative Survey Study

Background

Smartphone overuse can harm individual health and well-being. Although several studies have explored the relationship between problematic or excessive smartphone use and mental health, much less is known about effects on self-esteem, which is essential in having a healthy life, among adults with mental health disorders, including internet gaming disorder. Furthermore, given that smartphone usage differs by gender, little is known about gender differences in the relationship between smartphone overuse and self-esteem.

Objective

The objective of this study was to assess self-esteem among individuals with mental health disorders and explore the relationship with excessive smartphone use.

Methods

Participants were selected based on their responses to the internet gaming disorder assessment, which includes 9 items developed based on Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) criteria, from among a Korean cohort of smartphone users aged 20-40 years, resulting in a sample of 189 participants (men:120, women: 69). The Rosenberg self-esteem scale and the Korean smartphone addiction proneness scale were utilized to assess the outcome self-esteem with excessive smartphone use as the primary independent variable. Guided by the Bowlby attachment theory and prior studies, we selected several covariates. Generalized linear regression analyses, as well as subgroup analyses by gender, were performed.

Results

Among adults with internet gaming disorder, the average Korean smartphone addiction proneness scale score was significantly higher in women than that in men (41.30 vs. 37.94; P=.001), and excessive smartphone use was significantly more prevalent in women than it was in men (30.43% vs. 20.83%; P=.02). Our findings from the generalized linear regression analyses indicated that an increase in Korean smartphone addiction proneness scale score had a negative relationship with self-esteem among those with internet gaming disorder (β=–0.18, P=.001). Furthermore, our interaction models showed that, among those with internet gaming disorder, more men than women had lower self-esteem associated with an increase in Korean smartphone addiction proneness scale score and a high degree of smartphone overuse (β=–0.19, P=.004; β=–3.73, P<.001).

Conclusions

Excessive smartphone use was found to be adversely associated with self-esteem among young and middle-aged adults with internet gaming disorder; notably, more men than women were negatively influenced (regarding self-esteem) by smartphone overuse. Based on our findings, more efforts should be made to reduce excessive or problematic smartphone use by considering developing public health interventions or policy, particularly among those with mental health disorders such as internet gaming disorder.

Influence of hand and smartphone anthropometric measurements on hand pain and discomfort: A cross-sectional study

A good mobile phone design may increase the productivity of users, as well as their comfort. To achieve mobile users' satisfaction, there is a need to come up with an ideal measurement that would not strain the human's body parts used to control the devices.To investigate the correlation between smartphone and hand anthropometry measurements and the development of hand discomfort and pain.89 Ahlia University students between the ages of 17- and 30-year-old participated in this study. Participants completed a demographic data sheet and had both of their hand dimensions and grip strength measured.A total number of 89 participants were recruited in this study with (57.3%) females and (42.7%) males. 38% have had hand pain recently while 61.8% did not experience any hand pain. There was weak negative correlation between the phone size (r = -0.04, P = .7), hand size (r = -0.08, P = .5), and the hand grip strength (r = -0.03, P = .7) all with the reporting of hand pain. For the phone screen size and the hand lengths (r = 0.22, P = .13) there was weak positive correlation.Mobile phone manufacturers should take into account the users' comfort when designing their phones as this could lead to hand pain and other musculoskeletal problems. Furthermore, hand pain is multifactorial so hand size; phone size and grip strength may be taken into account.

Evaluating hand performance and strength in children with high rates of smartphone usage: an observational study

[Purpose] This study investigated the interaction effects between the levels of smartphone use and hand dominance on handgrip, pinch strengths, and functional hand performance in children. [Participants and Methods] A total of 60 children aged between 9 and 15 were assigned into two groups: Group A (high-frequency smartphone users) and Group B (low-frequency smartphone users). Use levels were determined according to the smartphone addiction scale-short version. A hand dynamometer and pinch gauge were used to measure handgrip and pinch strength respectively. Functions of the upper extremity and hand were scored using the Quick Disabilities of the Arm, Shoulder, and Hand questionnaire. [Results] Group A participants had reduced measurements in hand grip and pinch strength, especially in the dominant hand. However, Quick Disabilities of the Arm, Shoulder, and Hand scores indicated that hand function was decreased in the dominant hand whether the child was a high- or low-frequency smartphone user. [Conclusion] Results indicated that high levels of smartphone use diminished hand and pinch-grip strengths as well as and hand function. That is, hand and pinch-grip strengths were reduced in the dominant hands of high-frequency smartphone users. However, hand functions were affected in the dominant hands among both high and low-level smartphone users.

Musculoskeletal Injuries Are Commonly Reported Among Gastroenterology Trainees: Results of a National Survey

BACKGROUND

Endoscopy-related musculoskeletal injuries are increasingly recognized among gastroenterologists. While injury rates and risk factors have been studied among practicing gastroenterologists, little is known about rates among trainees during fellowship.

AIMS

This study analyzes the prevalence of endoscopy-related overuse injuries and risk factors for injuries among a national sample of gastroenterology (GI) fellows. We also surveyed GI fellowship program directors and fellows about perceptions of overuse injuries during GI training.

METHODS

We distributed a 29-item electronic survey to GI fellows at accredited programs in the USA in April 2016. Survey items included demographic information, questions pertaining to injuries, and level of agreement on the importance of ergonomics training in GI fellowship. Additionally, we distributed a 7-item electronic survey to fellowship program directors evaluating perception of overuse injuries and prevention during fellowship training. Fisher's exact test determined factors associated with sustaining an injury.

RESULTS

An estimated 1509 fellows received the survey. Eleven percent (n = 165) of gastroenterology fellows completed the survey. Twenty percent reported having a musculoskeletal injury. Female gender was the only factor associated with a higher rate of reported injury (p < 0.01). The most common injuries reported were thumb and other hand-related pain (n = 28 [64%]).

CONCLUSIONS

Musculoskeletal injuries may affect up to 20% of GI fellows. Female fellows more frequently report injuries and may be at particularly high risk which has not been found in previously reported surveys of practicing gastroenterologists. Standardized curricula on ergonomic considerations and injury prevention are needed to enhance GI fellowship training and reduce injury rates.

The Healthy e-Elderly People Assessment (HEPA) application

Purpose

The purpose of this paper is to evaluate health effects and determine the factors associated with health effects from smartphone and tablet use among the elderly in Thailand.

Design/methodology/approach

This study was a cross-sectional descriptive study. The participants comprised 490 elderly people. A self-administered questionnaire was used for data collection via the Healthy e-Elderly People Assessment mobile application in the Android operating system by Google which consists of five parts of a questionnaire. The variables were analyzed using SPSS such as frequency, percentage, mean and binary logistic regression.

Findings

Altogether, the participants were 223 males and 267 females; mean age=64.9±5.4. The average time spent using a mobile device was 2.8±1.9 h/day. Participants recorded that after use of either device, 59.0 percent experienced eye pain, 52.7 percent experienced dim eyes, 30.2 percent experienced tiredness, and 28.0 percent experienced moodiness. Socially, 26.8 percent recorded changes in social interaction. Periods of time using devices, time consumed in device usage (hours/day), the type of application, and the difference in times of use, place of usage and time spent in rest breaks from smartphone or tablet usage were significantly associated with health effects (p<0.05).

Originality/value

The elderly users may be at risk of several health effects from smartphone and tablet use. The potential gap in knowledge conceals some of the risk factors for the current health effects. Practical intervention to reduce health effects from the use of smartphones and tablets should be considered.

Musculoskeletal disorder and pain associated with smartphone use: A systematic review of biomechanical evidence

The number of smartphone users is growing dramatically. Using the smartphone frequently forces the users to adopt an awkward posture leading to an increased risk of musculoskeletal disorders and pain. The objective of this study is to conduct a systematic review of studies that assess the effect of smartphone use on musculoskeletal disorders and pain. A systematic literature search of AMED, CINAHL, PubMed, Proquest, ScienceDirect using specific keywords relating to smartphone, musculoskeletal disorders and pain was conducted. Reference lists of related papers were searched for additional studies. Methodological quality was assessed by two independent reviewers using the modified Downs and Black checklist. From 639 reports identified from electronic databases, 11 were eligible to include in the review. One paper was found from the list of references and added to the review. The quality scores were rated as moderate. The results show that muscle activity of upper trapezius, erector spinae and the neck extensor muscles are increased as well as head flexion angle, head tilt angle and forward head shifting which increased during the smartphone use. Also, smartphone use in a sitting position seems to cause more shift in head-neck angle than in a standing position. Smartphone usage may contribute to musculoskeletal disorders. The findings of the included papers should be interpreted carefully in light of the issues highlighted by the moderate-quality assessment scores.

Axial Rotation Test for Trapeziometacarpal Joint Hypermobility in the Normal Population

Background: The objective was to quantify joint laxity in healthy volunteers by measuring the passive axial rotation of the trapeziometacarpal joint using the axial rotation test.

Methods: Eighty volunteers (34 men and 46 women) were subjected to the axial rotation shear test and the degree of total rotational motion (TRM) was assessed. Volunteers were divided into Group I with a range of 18–50 years old and Group II for 51 years and older. Statistical analysis was performed.

Results: The average TRM in Group I was 32.3 mm for women, and 27.4 mm, for men (p = 0.04). The average TRM in women of Groups I and II, was 32.3 and 21.6 mm respectively, (p < 0.001). The average TRM in men of Groups I and II, was 27.4 and 19.4 mm (p < 0.001). In Group II the average TRM of women was 21.6 mm, and for men was 19.4 mm, which was not significantly different.

Conclusions: Young women have greater degree of rotational laxity in the TM joint compared to men of the same age group and to older women. The axial rotation test can quantify the degree of rotational laxity of the TM joint.

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.

Association Between Smartphone Use and Musculoskeletal Discomfort in Adolescent Students

Despite the substantial increase in the number of adolescent smartphone users, few studies have investigated the behavioural effects of smartphone use on adolescent students as it relates to musculoskeletal discomfort. The purpose of this study was to explore the association between smartphone use and musculoskeletal discomfort in students at a Taiwanese junior college. We hypothesised that the duration of smartphone use would be associated with increased instances of musculoskeletal discomfort in these students. This cross-sectional study employed a convenience sampling method to recruit students from a junior college in southern Taiwan. All the students (n = 315) were asked to answer questionnaires on smartphone use. A descriptive analysis, stepwise regression, and logistic regression were used to examine specific components of smartphone use and their relationship to musculoskeletal discomfort. Nearly half of the participants experienced neck and shoulder discomfort. The stepwise regression results indicated that the number of body parts with discomfort (F = 6.009, p < 0.05) increased with hours spent using ancillary smartphone functions. The logistic regression analysis showed that the students who talked on the phone >3 h/day had a higher risk of upper back discomfort than did those who talked on the phone <1 h/day [odds ratio (OR) = 4.23, p < 0.05]. This study revealed that the relationship between smartphone use and musculoskeletal discomfort is related to the duration of smartphone ancillary function use. Moreover, hours spent talking on the phone was a predictor of upper back discomfort.

Effects of button position on a soft keyboard: Muscle activity, touch time, and discomfort in two-thumb text entry

Intensive use of the thumbs for text entry on smartphones may contribute to discomfort, pain, or musculoskeletal disorders. This study investigated the effect of twenty-five button positions (5 rows × 5 columns) on a soft keyboard for two-thumb entry. Two experiments measured muscle activity, touch time, and discomfort as a function of the button positions. In Phase I, the muscle activities of two intrinsic (abductor pollicis brevis and first dorsal interossei) and two extrinsic (abductor pollicis longus and extensor digitorum communis) muscles associated with thumb motions were observed for ten college students (age: 24.2). In Phase II, touch time and discomfort were measured for 40 college students (age: 23.6). The results demonstrated that the %MVCs of the intrinsic muscles significantly increased when the thumbs flexed and abducted. Also, the button positions near the rest positions of the thumbs resulted in significantly shorter touch times (0.66 s) and lower discomfort ratings (0.70 pt) than their peripheral buttons (0.76 s; 2.29 pt).

Fingertip forces and completion time for index finger and thumb touchscreen gestures

Users actuate touchscreen computers by applying forces with their fingers to the touchscreen, although the amount and direction of the force is unknown. Our aim was to characterize the magnitude, direction and impulse of the force applied during single finger (tapping and sliding in four directions) and two finger gestures (stretch and pinch). Thirteen subjects performed repeated trials of each gesture. Mean(±SD) resultant force was 0.50(0.09)N for tap, 0.79(0.32)N to 1.18(0.47)N for sliding gestures, 1.47(0.63)N for pinch and 2.05(1.13)N for stretch. Mean resultant force was significantly less (p<0.04) for tap than for all gestures except slide right. The direction of force application was more vertical for the two-finger gestures as compared to the single- finger gestures. Tap was the fastest gesture to complete at 133(83)ms, followed by slide right at 421(181)ms. On average, participants took the longest to complete the stretch gesture at 920(398)ms. Overall, there are differences in forces, force direction, and completion times among touchscreen gestures that could be used to estimate musculoskeletal exposure and help forge guidelines to reduce risk of musculoskeletal injury.

Index finger and thumb kinematics and performance measurements for common touchscreen gestures

This study aimed to quantify differences in 7 touchscreen gestures. Eighteen participants performed index finger tapping, sliding in 4 orthogonal directions, and index finger and thumb pinch and stretch gestures on a touchscreen tablet computer. We hypothesized that two finger gestures would require longer task completion time and greater finger joint excursions than sliding gestures using only the index finger. We measured task completion times and finger joint kinematics. Tapping showed the fastest average (±SD) task completion time, 567(190) ms, of all gestures (p < 0.001). Pinch had faster task completion time, 765(277) ms, than all single-finger sliding gestures (p < 0.001). Stretch was faster to complete at 843(317) ms (p < 0.001) than all sliding gestures except slide right. Stretch demonstrated greater mean index finger metacarpophalangeal flexion/extension joint excursions, 63(16)°, compared to sliding gestures, 34(10)°, and tapping, 27(13)° (p < 0.01). Overall, two-finger gestures were faster to complete and showed greater joint excursions than single-finger sliding gestures.

Personality Factors Predicting Smartphone Addiction Predisposition: Behavioral Inhibition and Activation Systems, Impulsivity, and Self-Control

The purpose of this study was to identify personality factor-associated predictors of smartphone addiction predisposition (SAP). Participants were 2,573 men and 2,281 women (n = 4,854) aged 20–49 years (Mean ± SD: 33.47 ± 7.52); participants completed the following questionnaires: the Korean Smartphone Addiction Proneness Scale (K-SAPS) for adults, the Behavioral Inhibition System/Behavioral Activation System questionnaire (BIS/BAS), the Dickman Dysfunctional Impulsivity Instrument (DDII), and the Brief Self-Control Scale (BSCS). In addition, participants reported their demographic information and smartphone usage pattern (weekday or weekend average usage hours and main use). We analyzed the data in three steps: (1) identifying predictors with logistic regression, (2) deriving causal relationships between SAP and its predictors using a Bayesian belief network (BN), and (3) computing optimal cut-off points for the identified predictors using the Youden index. Identified predictors of SAP were as follows: gender (female), weekend average usage hours, and scores on BAS-Drive, BAS-Reward Responsiveness, DDII, and BSCS. Female gender and scores on BAS-Drive and BSCS directly increased SAP. BAS-Reward Responsiveness and DDII indirectly increased SAP. We found that SAP was defined with maximal sensitivity as follows: weekend average usage hours > 4.45, BAS-Drive > 10.0, BAS-Reward Responsiveness > 13.8, DDII > 4.5, and BSCS > 37.4. This study raises the possibility that personality factors contribute to SAP. And, we calculated cut-off points for key predictors. These findings may assist clinicians screening for SAP using cut-off points, and further the understanding of SA risk factors.

Ulnar Nerve Tendon Transfers for Pinch

Power and tip pinch are an integral part of intrinsic hand function that can be significantly compromised with dysfunction of the ulnar nerve. Loss of power pinch is one component that can significantly affect an individual's ability to perform simple daily tasks. Tip pinch is less affected, as this task has significant contributions from the median nerve. To restore power pinch, the primary focus must be on restoring the action of the adductor pollicis primarily, and if indicated the first dorsal interosseous muscle and flexor pollicis brevis.

Validity of a small low-cost triaxial accelerometer with integrated logger for uncomplicated measurements of postures and movements of head, upper back and upper arms

Repetitive work and work in constrained postures are risk factors for developing musculoskeletal disorders. Low-cost, user-friendly technical methods to quantify these risks are needed. The aims were to validate inclination angles and velocities of one model of the new generation of accelerometers with integrated data loggers against a previously validated one, and to compare meaurements when using a plain reference posture with that of a standardized one. All mean (n = 12 subjects) angular RMS-differences in 4 work tasks and 4 body parts were <2.5° and all mean median angular velocity differences <5.0 °/s. The mean correlation between the inclination signal-pairs was 0.996. This model of the new generation of triaxial accelerometers proved to be comparable to the validated accelerometer using a data logger. This makes it well-suited, for both researchers and practitioners, to measure postures and movements during work. Further work is needed for validation of the plain reference posture for upper arms.

Two-handed grip on a mobile phone affords greater thumb motor performance, decreased variability, and a more extended thumb posture than a one-handed grip

Holding a mobile computing device with two hands may affect thumb motor performance, joint postures, and device stability compared to holding the device and tapping the touchscreen with the thumb of the holding hand. We tested the hypotheses that holding a touchscreen mobile phone with two hands lead to increased thumb motor performance, different thumb postures, and decreased device movement relative to using one hand. Ten right-handed participants completed reciprocal thumb tapping tasks between emulated keys on a smartphone in either a one- (portrait) or two-handed (landscape) grip configuration. Effective index of performance measured from Fitts' Law was 9% greater (p < 0.001), movement time 7% faster (p < 0.001), and taps were 4% more precise (p < 0.016) for the two-handed grip. Tapping with a two-handed grip involved significantly different wrist and thumb postures than a one-handed grip. Variability of the computing device's movement was 36-63% lower for the two-handed grip compared to the one-handed grip condition (p < 0.001). The support for our hypotheses suggests that a two-handed grip results in increased performance and more extended wrist and thumb postures than a single-handed grip. Device designs that allow two-handed grips may afford increased performance relative to a one-handed grip.

Temporal Co-Variation between Eye Lens Accommodation and Trapezius Muscle Activity during a Dynamic Near-Far Visual Task

Near work is associated with increased activity in the neck and shoulder muscles, but the underlying mechanism is still unknown. This study was designed to determine whether a dynamic change in focus, alternating between a nearby and a more distant visual target, produces a direct parallel change in trapezius muscle activity. Fourteen healthy controls and 12 patients with a history of visual and neck/shoulder symptoms performed a Near-Far visual task under three different viewing conditions; one neutral condition with no trial lenses, one condition with negative trial lenses to create increased accommodation, and one condition with positive trial lenses to create decreased accommodation. Eye lens accommodation and trapezius muscle activity were continuously recorded. The trapezius muscle activity was significantly higher during Near than during Far focusing periods for both groups within the neutral viewing condition, and there was a significant co-variation in time between accommodation and trapezius muscle activity within the neutral and positive viewing conditions for the control group. In conclusion, these results reveal a connection between Near focusing and increased muscle activity during dynamic changes in focus between a nearby and a far target. A direct link, from the accommodation/vergence system to the trapezius muscles cannot be ruled out, but the connection may also be explained by an increased need for eye-neck (head) stabilization when focusing on a nearby target as compared to a more distant target.

Musculoskeletal disorders of the upper extremities due to extensive usage of hand held devices

OBJECTIVE

The use of hand held devices (HHD) such as mobile phones, game controls, tablets, portable media players and personal digital assistants have increased dramatically in past decade. While sending a text message or using the controls of the HHD the users need to use their thumb and other palm muscles extensively. The objective of this study was to describe the risk factors and clinical features of the musculoskeletal disorders (MSDs) arising due to usage of hand held devices and to evaluate the effectiveness of a sequenced rehabilitation protocol.

METHODS

A retrospective report analysis of 70 subjects, who were diagnosed to have a MSD affecting the upper extremities, was conducted. Medical charts from a tertiary level rehabilitation centre from 2005-2013 were analysed. All the subjects reported pain in their upper extremities following extensive usage of HHD and were examined and diagnosed to have a MSD by an orthopaedic and rehabilitation physician. After the assessment and diagnosis, all the patients underwent rehabilitation using a sequenced protocol.

RESULTS

All the subjects reported pain in the thumb and forearm with associated burning, numbness and tingling around the thenar aspect of the hand, and stiffness of wrist and hand. 43 subjects had symptoms on the right side; 9 on left and 18 had bilateral symptoms. Correlation was found between hand dominance and MSD. 33 subjects complained of onset of symptoms following extensive text messaging. All the subjects were diagnosed to have tendinosis of Extensor Pollicis Longus and Myofascial Pain Syndrome affecting the 1st interossei, thenar group of muscles and Extensor Digitorum Communis. 23 of the subjects were senior executives, among these 7 were CEO's of major multinational companies in India. All the subjects recovered completely following the rehabilitation.

CONCLUSIONS

The study concluded that mobile phones and gadgets that promoted the predominant usage of thumb or only one finger while texting or using the controls were associated with a higher prevalence of MSDs. Treatment using a sequenced rehabilitation protocol was found to be effective.

An ergonomics study of thumb movements on smartphone touch screen

This study investigated the relationships between thumb muscle activity and thumb operating tasks on a smartphone touch screen with one-hand posture. Six muscles in the right thumb and forearm were targeted in this study, namely adductor pollicis, flexor pollicis brevis, abductor pollicis brevis (APB), abductor pollicis longus, first dorsal interosseous (FDI) and extensor digitorum. The performance measures showed that the thumb developed fatigue rapidly when tapping on smaller buttons (diameter: 9 mm compared with 3 mm), and moved more slowly in flexion-extension than in adduction-abduction orientation. Meanwhile, the electromyography and perceived exertion values of FDI significantly increased in small button and flexion-extension tasks, while those of APB were greater in the adduction-abduction task. This study reveals that muscle effort among thumb muscles on a touch screen smartphone varies according to the task, and suggests that the use of small touch buttons should be minimised for better thumb performance.