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

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

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

Determinants of survival of common childhood cancers in Iran

Background: Cancer is the second most common cause of morbidity and mortality in children. This study aimed to epidemiologically and demographically assess common cancers in children in Iran. Materials and Methods: This cohort study was conducted on children registered in Mahak Hospital and Rehabilitation Complex (which is a non-governmental organizations (NGO)-related hospital for only malignant diseases). A total of 2232 questionnaires were filled out for cancer patients between 2007 and 2016. The factors including age, gender, race, family history, type of treatment, and type of cancer were entered into Cox regression model to examine their effect on mortality of children diagnosed with cancer. Results: The Cox regression model showed that age, race, type of cancer, family history of cancer, and type of treatment had a significant effect on mortality of children diagnosed with cancer (P < 0.05). The hazard ratio (HR) of mortality in 10–15 years old was higher than that of 1–5 years old (P = 0.03, HR = 1.3). The HR of mortality in patients with brain tumor (P < 0.01, HR = 2.24), sarcoma (P < 0.01, HR = 2.32), and neuroblastoma (P < 0.01, HR = 2.56) was twice the value in patients with leukemia. The HR of mortality in patients who had a family history of cancer was higher than that of patients without it (P < 0.01, HR = 1.33). Patients who had undergone chemotherapy along with surgery and radiotherapy (P = 0.02, HR = 0.68) and patients who received chemotherapy along with surgery (P = 0.01, HR = 0.67) had a lower HR of mortality compared to the chemotherapy group. Conclusion: Young age, multidisciplinary approach, and absence of family history were associated with lower hazard of death in children diagnosed with cancer; brain tumor, leukemia, and sarcoma had higher hazard of mortality compared to leukemia. Children with a family history of cancer should be under regular follow-up. Treatment should be multidisciplinary and comprehensive