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

ObjectiveThe 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).BackgroundAlong 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.MethodTwenty-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.ResultsWorking 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 \u3c 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.ConclusionThis 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.ApplicationResults 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

Ergonomic Assessment of a Seat Back Support (Spine Fit)

Background & Objectives : In case of inappropriateness of the dimensions of chairs or when users feel pain and pressure in their lumbar region due to poor posture, damage to the spine can be prevented using some additional supports. The aim of this study was ergonomic evaluation of one of these supportive products named “Spine Fit”. Methods : In this descriptive and cross-sectional study, in the first stage, five ergonomists evaluated the product regarding its dimension, adjustability, material, conformity, and manufacturer claims. Then, three groups of workers including office workers, office workers with low back pain, and bus drivers filled out a self-administered questionnaire after using Spine Fit . Results : For the first stage, an acceptable adjustability and dimension was found. Conformity for different kinds of office and bus seats was mostly fair. Findings from the second stage revealed that the subjects in three groups were satisfied regarding seats comfort and ease of use. Concerning the conformity of Spine Fit, it was in good level among office workers, while different levels of conformity were observed by drivers of different models of bus . Conclusion : Spine Fit supports back region based on its supportive role in pelvis, lumbar vertebrae column and thoracic spine. Moreover, Spine Fit features that reduce sweating can improve individuals’ convenience

Risk assessment of the Manual Handling of Patients in remedial wards of Qazvin hospitals and its relationship with incidence of musculoskeletal disorders

Background & Objectives : Approximately one third of all reported work-related incidents are triggered by manual handling. The proportion of incidents associated with manual handling in health and social care is 38%. Lifting and transferring patients is the task that is most often cited as a cause of manual handling incidents and of back injury in the healthcare sector. The aim of this study is to determine the MAPO index for remedial hospital wards of Qazvin and considering its relationship with incidence and intensity of musculoskeletal disorders among servers whose main task is manual handling of patients . Methods : In this cross sectional study, 54 cases of servers from 23 wards of 4 Hospitals was considered. The data was collected using the demographic characteristic questionnaire, the Verbal pain intensity scale, the Nordic questionnaire and the MAPO checklist. Statistical Analysis of collected data was performed with SPSS 22. Results : One year prevalence of musculoskeletal disorders was 75.9% and this amount during performing this study was reported 53.7%. Regarding to different levels of MAPO score, just 5.5% of surveyed personnel were in safe zone. 18.5% of them exposed to moderate risk of musculoskeletal disorders and 76 % were at high risk. Also prevalence of musculoskeletal disorders incidents and pain intensity had significantly associated with the MAPO index score. Conclusion : Regarding to association between MAPO index score and prevalence of musculoskeletal disorders, to reducing incidences risk, improvement of MAPO index parameters to reducing its amount will be effective

Investigating the relationship between cognitive failures and workload among nurses of Imam Khomeini and Vali-e-Asr hospitals in Tehran

Introduction: High level of workload and its consequent cognitive failures are among factors which impact nurses&rsquo; behavior, performance, and efficiency. This study aimed to investigate the relationship between nurses&rsquo; cognitive failures and perceived workload. Material and Method: This cross-sectional and descriptive-analytical study was carried out among 150 male and female nurses, working in different units of Emam Khomeini and Vali-e-Asr hospitals in Tehran in 2013. NASA task load index (NASA-TlX) and Cognitive Failure Questionnaire (CFQ) were used to assess workload and cognitive failures, respectively. Data were analyzed using Pearson Correlation, Independent sample t-test, and one-way ANOVA statistical tests with SPSS software version 20. Result: Pearson and Spearman correlation coefficients test results showed a significant relationship between nurses&rsquo; mental workload and their memory for names (P-value<0.001). Moreover, there was significant association between physical workload and memory, attention and total cognitive failures (CFQ total) (P-value<0.05). Perceived frustration mong nurses was significantly correlated with memory, attention, motor functions and total cognitive failures (P-value<0.05). Conclusion: The results showed a high level of workload among study nurses. Furthermore, the relationships between some dimensions of mental workload and cognitive failures were confirmed, so that an increase in workload dimension can lead to more cognitive failures while doing task

Ergonomics Risk Assessment with Participation of Supervisors in Production Line: a Successful Experience in Pars Khodro Company

Background & Objectives: According to previous researches, workers' participation in issues affecting their working condition is the key to success in ergonomics interventions in working environments. Therefore, the present study was performed to increase active particapitation of supervisors in production line and also to identify and assess ergonomics risks and presenting modification actions (Kaizen) by themselves in Pars Khodro automobile manufacturing company. Methods: A manual regarding lifting objects and body postures, according to the Finish evaluation method, was provided for supervisors in production line and related trainings were presented to them. Then, they were asked to insert the results of their assessments and suggestions in special forms during one year. The presented assessments and suggestions were examined by ergonomics experts. Results: According to the assessments conducted by supervisors, 26 work stations had high ergonomics risks, 51 had ergonomics risks with an average level, and 45 had low ergonomics risks. Moreover, the number of required Kaizens presented by supervisors was increased from 18 cases in the first year to 42 cases in the second year, after implementation of ergonomics training and identifying and assessing ergonomic risks by supervisors. Conclusion: Empowering and training supervisors increased workers' participation. In case of adequate training, supervisors can present practical solutions to reduce ergonomics risks in their workstations

The Effect of Repetitive Lifting on Trunk Muscles’ Fatigue and Kinematics of Spine and Load-in-Hand

Introduction: Given the high prevalence of low back pain in manual handling activities, its known relationship with spinal loads, and the role of muscular fatigue and the body’s adaptive mechanisms to counteract fatigue, this study investigated the effect of repetitive lifting tasks on trunk muscular fatigue and the kinematics of the spine and load-in-hand. Material and Methods: Eighteen male volunteers lifted a box from the floor to their waist height at a pace of ten lifts per minute until they could no longer continue the task and reported the highest level of exhaustion. Kinematic data and muscle electromyographic activity were simultaneously recorded using a motion capture system and an electromyography device. In this study, average trunk flexion angle and trunk angular velocity were calculated as trunk kinematic variables, while average box vertical travel distance, average box horizontal displacement from L5-S1, and average box vertical displacement velocity were considered as box kinematic variables. The median frequency of electromyographic signals from selected muscles was quantified as a muscle fatigue indicator. Since subjects performed different lifting cycles, the total number of cycles was divided into five distinct blocks for data analysis. Results: The results showed significant effects of lifting trial blocks on trunk angle (p=0.004) and vertical box displacement (p<0.001). Median frequency was significantly affected by lifting blocks for right (p=0.016) and left erector spinae (p=0.014), right (p=0.021) and left multifidus (p<0.001), right latissimus dorsi (p=0.001), and left rectus abdominis (p=0.039). Conclusion: Overall, the results highlight variations in most kinematic parameters and a reduction in the frequency content of EMG signal spectra. These changes serve as indices of the central nervous system’s control over lifting behavior under dynamic conditions. A better understanding of these central nervous system adaptations could have practical applications in interventions such as workstation design, exoskeleton development, and worker training to manage musculoskeletal disorders

The effect of using cervical exoskeleton on the neck and shoulder muscles electrical activity during overhead work

Introduction: The use of exoskeletons as a new ergonomics intervention to reduce musculoskeletal disorders risk factors and increase human performance has emerged in the fourth-generation industrial revolution. The aim of this study was to assess the cervical exoskeleton effect on the neck and shoulder muscles electrical activity. Material and Methods: In this experimental study, 14 male participants were asked to perform the simulated overhead work with and without using the cervical exoskeleton at two neck postural angles randomly. During the task, electromyography of the target muscles in the neck and shoulders was recorded. In addition, at the end of each task, participants completed a perceived discomfort questionnaire. Electromyographic signals were processed with Matlab 2017b software and the level of the electrical activity of the target muscles was normalized to the maximum muscle activity. Data analysis was performed using Random intercept mix model in STATA 14 software. Results: Mean perceived discomfort in the neck and shoulders regions significantly reduced by the exoskeleton device, but there was no statistically significant difference in other areas. Also, the mean activity level of sternocleidomastoid and splenius capitis muscles on the right and left was significantly decreased during the use of the cervical exoskeleton. However, this difference showed a significant increase in trapezius muscles. Conclusion: The use of the neck exoskeleton was associated with a reduction of muscle electrical activity and the perceived discomfort in the neck area. These results may be related to transferring neck and head weight by the exoskeleton retaining jack during the neck extension to other areas of the body. The exoskeleton design did not provide support for the shoulder and arm area, which explains the reason for the non-significant results in the shoulder area. Using the exoskeleton with the additional support in shoulder area could be considered as an ergonomic intervention in such overhead works

Evaluating Effects of Heat Stress on Cognitive Function among Workers in a Hot Industry

Background:Heat stress, as one of the most common occupational health problems, can impair operators' cognitive processes. The aim of this study was to evaluate the impact of thermal stress on cognitive function among workers in a hot industry. Methods: In this cross-sectional study conducted in Malibel Saipa Company in 2013, workers were assigned into two groups: one group were exposed to heat stress (n=35), working in casting unit and the other group working in machin-ing unit (n=35) with a normal air conditioning. Wet Bulb Globe Temperature was measured at three heights of ankle, abdomen, and head. In order to evalu-ate the effects of heat stress on attention and reaction time, Stroop tests 1, 2, and 3 were conducted before starting the work and during the work. Results: A significant positive correlation was observed between WBGT and test duration (P=0.01) and reaction time of Stroop test 3 (P=0.047), and be-tween number of errors in Stroop tests 1, 2, and 3, during the work (P= 0.001). Moreover, Stroop test 3 showed a significant higher score for both test dura-tion and reaction time of workers in case group. Conclusion: Results of the present study, conducted in a real work environment, confirmed the impairment of cognitive functions, including selective attention and reaction time, under heat stress conditions