Evaluation of ergonomic risks for work-related musculoskeletal disorders of nursing tasks in Korea.

Among all industrial accident-induced diseases, musculoskeletal disorders (MSDs) are most prominently observed among nurses. The physical load of everyday tasks involved in nursing work was assessed in this study using a developed risk index, whereby the physical burden was evaluated using the exposure duration and work intensity levels. This survey targeted nine small, medium and large-sized hospitals in South Korea and categorized representative nursing tasks into six groups. The subtasks within these six categories (evaluated as high risk) included changing a patient's posture and assisting with walkers or wheelchairs, transporting/handling drug carts, bathing patients, replacing bedding, traction therapy, cardiopulmonary resuscitation and artificial manual breathing unit, and computer work. The risk index ratio was significantly different by task type for each task. We demonstrated that the risk index developed in this study can be used to evaluate MSDs in hospitals.

Research trends in ergonomics, industrial safety and health: semantic network and topic analyses.

We evaluated the research trends in ergonomics, industrial safety and health from the 1980s to the present. In the ergonomics area, keywords and abstracts from five journals were analyzed. For industrial safety and health, six journal databases were evaluated. A frequency analysis, a semantic network of keywords and a topic network of abstracts were conducted. The results of ergonomics showed that 'macro-ergonomics' and 'manual material handling' were the most popular topics, and 'ergonomic' and 'electromyography' were the most cited keywords. 'Posture' and 'biomechanics' were the most frequently used with high centrality. The results of industrial safety and health showed that 'job stress' and 'organizational safety' were the most popular topics, and 'occupational exposure' and 'occupational health' were the most cited keywords. 'Dust' and 'exposure' were frequently used with high centrality. The results would be helpful in understanding the trends of research efforts and foreseeing trends of future research.

Reduced Muscle Activity of the Upper Extremity in Individuals with Spinal Cord Injuries.

Compromised physical ability due to musculoskeletal impairment among spinal cord injury (SCI) patients is known to negatively affect their quality of life. It is essential to comprehensively understand the muscle strength of the upper extremity among patients with SCI to enhance muscle function and capacity to engage in an active lifestyle. The objective of this study was to evaluate the muscle strength of 15 upper extremity muscles among patients with SCI and compare the relative weakness of individual muscles to the control group. Seven male patients with SCI with ASIA impairment scale D and E and 33 males in the control group participated in this study. Each participant performed maximal voluntary contraction of individual muscles, and the electromyography data were recorded. The results showed that the majority of the upper extremity muscles (12 out of 15) showed considerable weakness (24 to 53%) relative to the control group. Furthermore, the relative strength (ranking) of individual muscles among 15 upper extremity muscles was different between patients with SCI and the control group. This information would be useful to the selective strengthening of specific muscles as an intensive rehabilitation effort and prevent overuse and adverse injuries due to excessive muscle training.

Prediction and comparison of postural discomfort based on MLP and quadratic regression.

OBJECTIVE: The objective of this study was to predict postural discomfort based on the deep learning-based regression (multilayer perceptron [MLP] model). METHODS: A total of 95 participants performed 45 different static postures as a combination of 3 neck angles, 5 trunk angles, and 3 knee angles and rated the whole-body discomfort. Two different combinations of variables including model 1 (all variables: gender, height, weight, exercise, body segment angles) and model 2 (gender, body segment angles) were tested. The MLP regression and a conventional regression (quadratic regression) were both conducted, and the performance was compared. RESULTS: In the overall regression analysis, the quadratic regression showed better performance than the MLP regression. For the postural discomfort group-specific analysis, MLP regression showed greater performance than the quadratic regression especially in the high postural discomfort group. The MLP regression also showed better performance in predicting postural discomfort among individuals who had a variability of subjective rating among different postures compared to the quadratic regression. The deep learning for postural discomfort prediction would be useful for the efficient job risk assessment for various industries that involve prolonged static postures. CONCLUSIONS: The deep learning for postural discomfort prediction would be useful for the efficient job risk assessment for various industries that involve prolonged static postures. This information would be meaningful as basic research data to study in predicting psychophysical data in ergonomics.

Effects of Two Foot-Ankle Interventions on Foot Structure, Function, and Balance Ability in Obese People with Pes Planus.

Obese people are prone to foot deformities such as flat feet. Foot management programs are important to prevent them. This study investigated the effects of two foot-ankle interventions on balance ability, foot arch, ankle strength, plantar fascia thickness, and foot functions in obese people with pes planus for four weeks. The experiment was designed as a randomized controlled trial. Twenty-four participants who met the inclusion criteria were selected, and they were randomly assigned to either a short foot group (SFG) or proprioceptive neuromuscular facilitation group (PNFG) according to foot-ankle intervention. Two interventions were commenced three times a week for 20 min over four weeks. The tests were conducted at two intervals: pre-intervention and at four weeks. The tests were conducted in the following order: the patient-specific functional scale test (PSFS), an ultrasound of the plantar fascia, the navicular drop test, balance test, and the four-way ankle strength test. Two groups showed significant differences in balance ability, foot arch, ankle strength, plantar fascia thickness, and foot functions between pre-test and post-test (p < 0.05). PNFG had significantly higher dorsiflexor and invertor strength than SFG (p < 0.05). SF and PNF interventions were effective to improve balance ability, foot arch, ankle strength, plantar fascia thickness, and foot functions in obese people with pes planus. Additionally, PNF intervention is more beneficial in increasing the dorsiflexor and invertor strength compared to SF intervention.

A deep learning-based method for grip strength prediction: Comparison of multilayer perceptron and polynomial regression approaches.

The objective of this study was to accurately predict the grip strength using a deep learning-based method (e.g., multi-layer perceptron [MLP] regression). The maximal grip strength with varying postures (upper arm, forearm, and lower body) of 164 young adults (100 males and 64 females) were collected. The data set was divided into a training set (90% of data) and a test set (10% of data). Different combinations of variables including demographic and anthropometric information of individual participants and postures was tested and compared to find the most predictive model. The MLP regression and 3 different polynomial regressions (linear, quadratic, and cubic) were conducted and the performance of regression was compared. The results showed that including all variables showed better performance than other combinations of variables. In general, MLP regression showed higher performance than polynomial regressions. Especially, MLP regression considering all variables achieved the highest performance of grip strength prediction (RMSE = 69.01N, R = 0.88, ICC = 0.92). This deep learning-based regression (MLP) would be useful to predict on-site- and individual-specific grip strength in the workspace to reduce the risk of musculoskeletal disorders in the upper extremity.

Classification of Whole-Body Postural Discomfort Using Cluster Analysis.

The objectives of this study were to evaluate the effect of gender and postures of the neck, trunk, and knee on overall postural discomfort, and to classify combined postures into different postural discomfort groups. A total of 95 participants (42 males and 53 females) performed 45 different static postures, which were a combination of 3 neck angles, 5 trunk angles, and 3 knee angles, and rated the perceived postural discomfort. Non-hierarchical K-means cluster analysis was employed to classify the 45 different combined postures into several postural discomfort groups. Postural discomfort was significantly affected by gender and postures of the neck, trunk, and knee (p < 0.001). Three clusters (high, medium, and low discomfort) were identified and the postural discomfort was significantly different between clusters (p < 0.001). The high discomfort group consisted of mostly males with high knee and trunk flexion angles and a moderate neck flexion angle. The low discomfort group was female-dominant with low neck and trunk flexion angles and a moderate knee flexion angle. The different flexibility (stiffness) of the joint motions between genders may affect the gender difference in postural discomfort. The knee and trunk postures were critical to the postural balance, which may affect the perception of whole-body discomfort. This result will be useful for developing and improving postural observation tools.

A Taxonomy of the Common Tasks and the Development of a Risk Index for Physical Load Assessment in Nursing Job.

BACKGROUND: Nursing service is a nonroutine work with an excessive physical load and diverse tasks. This study derived representative common tasks based on the frequently occurring tasks with a high physical load in the nursing workers' daily work and developed indicators to evaluate the work risk by reflecting the characteristics of nonroutine work. METHODS: Common tasks were classified through the following stages: literature review, first focus group interview (FGI) with experts, first classification of common tasks, second FGI with hospital health managers, a survey of nursing service workers, and the final classification of common tasks for each task type. To develop an objective risk index for physical load assessment, we investigated the frequency and duration of the derived common tasks via survey. RESULTS: Nursing common tasks were categorized into six task types and 56 subtasks. To evaluate the risks of various tasks in nonroutine works, three frequencies and three working time levels were defined by examining the task frequency and working hours. Exposure time was defined to reflect the characteristics of a nonroutine job. The final risk assessment was the product of the exposure time level and job intensity level. From this, four risk action levels were derived. CONCLUSION: This study has the advantage of solving the problem of focusing on some tasks in evaluating the physical load. It was meaningful in that a new risk assessment index based on exposure time was proposed based on the development of an evaluation scale for frequency and time by reflecting the characteristics of nonroutine work.

Moderated Mediation Effect of Mindfulness on the Relationship Between Muscular Skeletal Disease, Job Stress, and Turnover Among Korean Firefighters.

BACKGROUND: This study investigated the effect of increased job stress, caused by musculoskeletal disease (MSD) among firefighters, on a firefighter's intention to leave the profession, henceforth referred to as "turnover intention," and verified the moderating effect of mindfulness on such a relationship. METHODS: A survey involving a total of 549 Korean male firefighters as participants was conducted herein, and the following results were obtained: the mediation effect of the MSD to turnover intention through job stress was confirmed, and the indirect effect of job stress was verified. RESULTS: We verified the moderated mediation effect of mindfulness on the relation:MSD, job stress, and turnover intention. The conditional indirect effect for middle and high levels of mindfulness is significant. CONCLUSION: The result of this study is supported by proofs of the relationship between a firefighter's MSD, job stress, and turnover intention, and these case studies reveal the moderated mediation effect of dispositional mindfulness.

Three-Dimensional Ankle Exercise with Combined Isotonic Technique for an Obese Subject with Plantar Fasciitis: A Case Study.

Background and objectives: Obese people have many foot-related disorders and plantar fasciitis (PF) is the most common disorder among them. However, research on the role of therapeutic exercises in PF is lacking and there is no evidence to suggest its benefits. As such, a further insight into therapeutic exercises is needed within this group. This case study investigated the effect of three-dimensional (3D) ankle exercises using a combined isotonic (CI) technique on function and balance in an obese subject with PF. Material and methods: The subject in this study was a 28-year-old obese woman who was diagnosed with PF by an orthopedic surgeon. A 3D ankle exercise program was commenced three times a week for 15 min over 4 weeks. The evaluations were conducted at five intervals: pre-test, and at 1, 2, 3 and 4 weeks from the initiation of the intervention. The tests were conducted in the following order: the patient-specific functional scale test (PSFS), an ultrasound of the plantar fascia, the heel pressure and balance test, the pressure pain threshold (PPT), and the 4-way ankle strength test. Results: The mean score of the PSFS test reduced by 70.55% after 4 weeks of the intervention. The thickness of the plantar fascia and heel pressure measured during single-leg standing decreased by 6.67% and 10.37%, respectively, after 4 weeks of the intervention. The anteroposterior and medial-lateral balance ability showed improvements of 8.29% and 8.61%, respectively, after 4 weeks of the intervention. The PPT improved by 38.01% after 4 weeks of the intervention. In the 4-way ankle strength test, dorsiflexion, plantar flexion, inversion, and eversion increased by 14.46%, 9.63%, 4.3% and 13.25%, respectively, after 4 weeks of the intervention. Conclusion: 3D ankle exercises utilizing the CI technique were shown to be effective in improving foot function, pressure pain, and muscle strength in dorsiflexion and inversion in an obese patient with PF.

Determination of maximum acceptable and comfortable height during one-handed lifting.

BACKGROUND: One-handed lifting commonly occurs in the industry. Specific guidelines of proper heights during one-handed lifting could be valuable information to design or to assess the risk of work environment. OBJECTIVE: The objective of this study was to determine the maximum acceptable height and comfortable height during one-handed vertical lifting by gender, participant height, hand, and object weight. METHODS: Based on the psychophysical method, 72 males and 50 females, divided into four different height groups, determined their maximum acceptable and comfortable heights by each hand (left and right) and various object weights (1 kg, 3 kg, 5 kg, and 8 kg). RESULTS: Males revealed significantly greater maximum acceptable heights (males: 157 cm; females: 135 cm) and higher comfortable heights (males: 104 cm; females: 96 cm) compared to females. The participants' heights, which hand was used to lift, and the object weight were significant factors in determining the maximum acceptable height for both males and females. The multiple linear regression model of the maximum acceptable height showed more robust predictive power (R2 = 0.55) compared to the comfortable height (R2 = 0.20) as a function of gender, participant height, hand, and object weight. CONCLUSIONS: Results suggest that gender, participant height, hand, and object weight are important variables to consider when determining the proper surface height of one-handed vertical lifting. Using the robust predictive model, an appropriate maximum acceptable height could be suggested based on the material handler's anthropometric information and object weight.

Effect of hand postures and object properties on forearm muscle activities using surface electromyography.

Introduction. The objective of this study was to measure the effect of hand postures and object properties on nine forearm muscle activities and their contribution using surface electromyography. Methods. Ten male university students participated in the experiment. The objects used were cylindrical and rectangular, with lengths and weights of 2, 4, 6 and 8 cm and 400, 800, 1400 and 1800 g. The experimenter told the participant to pick up the object using a particular hand posture, lift the object to approximately shoulder height and maintain this posture for 3 s. Results. The hand posture, object size and object weight greatly influenced the muscle activities, but the object shape did not. Pinching with two or three fingers yielded the greatest muscle activities with the 8-cm, 1800-g object. The extensor pollicis longus and flexor pollicis longus muscles exhibited the highest submaximal voluntary contraction. Conclusion. This study provides basic information about the specific activities of the forearm muscles and the effects of the hand postures and object properties on those activities.

PEGylated Erythropoietin Protects against Brain Injury in the MCAO-Induced Stroke Model by Blocking NF-κB Activation.

Cerebral ischemia exhibits a multiplicity of pathophysiological mechanisms. During ischemic stroke, the reactive oxygen species (ROS) concentration rises to a peak during reperfusion, possibly underlying neuronal death. Recombinant human erythropoietin (EPO) supplementation is one method of treating neurodegenerative disease by reducing the generation of ROS. We investigated the therapeutic effect of PEGylated EPO (P-EPO) on ischemic stroke. Mice were administered P-EPO (5,000 U/kg) via intravenous injection, and middle cerebral artery occlusion (MCAO) followed by reperfusion was performed to induce in vivo ischemic stroke. P-EPO ameliorated MCAO-induced neurological deficit and reduced behavioral disorder and the infarct area. Moreover, lipid peroxidation, expression of inflammatory proteins (cyclooxygenase-2 and inducible nitric oxide synthase), and cytokine levels in blood were reduced by the P-EPO treatment. In addition, higher activation of nuclear factor kappa B (NF-κB) was found in the brain after MCAO, but NF-κB activation was reduced in the P-EPO-injected group. Treatment with the NF-κB inhibitor PS-1145 (5 mg/kg) abolished the P-EPO-induced reduction of infarct volume, neuronal death, neuroinflammation, and oxidative stress. Moreover, P-EPO was more effective than EPO (5,000 U/kg) and similar to a tissue plasminogen activator (10 mg/kg). An in vitro study revealed that P-EPO (25, 50, and 100 U/mL) treatment protected against rotenone (100 nM)-induced neuronal loss, neuroinflammation, oxidative stress, and NF-κB activity. These results indicate that the administration of P-EPO exerted neuroprotective effects on cerebral ischemia damage through anti-oxidant and anti-inflammatory properties by inhibiting NF-κB activation.

Development of the fall prevention index on the movable scaffold for construction workers.

BACKGROUND: Falls are caused by difficulties in maintaining stable posture or center of pressure (COP). Studies on construction-related falls and their prevention are limitedOBJECTIVE:To propose a fall prevention index (FPI) based on the working environment at height (with or without a handrail) and experience of workers on movable scaffolds. METHODS: Thirty participants were enrolled, and their COP distances were measured at the time of falling in the anterior-posterior (AP), mediolateral (ML), and diagonal directions. RESULTS: The probability of falling in the diagonal direction is almost zero for workers with more than 20 years of experience and that in the AP direction is almost zero for workers with up to 30 years of experience. There was almost zero probability of falling in the ML direction for workers with >15 years of experience. This index can be used as a tool for predicting the risk of falls, screening workers, and implementing proactive measures to prevent falling accidents on work sites. CONCLUSIONS: Preventing falls from movable scaffolds (and height in general) is needed in the construction industry. We propose a fall prevention index based on the working environment (at height, with or without handrail) and experience of workers on movable scaffolds.

Job satisfaction and job-related stress among nurses: The moderating effect of mindfulness.

BACKGROUND: Job stress can positively influence individuals' work motivation; however, it is more typical for job stress to have adverse physical and psychological effects, which in turn undermine job satisfaction. OBJECTIVE: The present study has two purposes: to evaluate the effect of the health-promotion lifestyle and job stress to job satisfaction and turnover intention, respectively; and to investigate the moderating effect of mindfulness on each relationship. METHODS: The present study surveyed 200 nurses employed at small-to-medium-sized hospitals in South Korea. To verify the internal consistency, the reliability of the scales that was administered with the Cronbach's alpha. Correlations between mindfulness, health-promotion lifestyle, job satisfaction, stress factors, and turnover intention were analyzed. The moderating effect of mindfulness on the relationships among aforementioned measures were evaluated. RESULTS: We found significant associations between the health-promotion lifestyle and job satisfaction (p < 0.001), and mindfulness had a moderating effect on the relationship between the health-promotion lifestyle and job satisfaction (p < 0.05). CONCLUSIONS: The enhancing effect of mindfulness in these relationships can suggest an important role of mindfulness in the relationship between life style and job attitude.

Investigation of a strategy for improving the Size Korea anthropometric database.

BACKGROUND: It is important for the designers and manufacturers to produce products with good usability and fit. The Korean anthropometric database is important as Korean industries focus on developing products with better usability. OBJECTIVE: To investigate how well the present national Size Korea anthropometric database adopted by companies and industries in Korea, in particular how well the dynamic anthropometric data are adopted. METHODS: The investigation methodology consisted of three stages: literature review, expert review and in-depth interviews. The literature review was based on a PubMed search. An online survey of 1,000 Korean civilians was carried out using a questionnaire developed by experts in anthropometry. Finally, industry professionals and professors participated in in-depth interviews. RESULTS: The anthropometric data appear to be used mainly by universities and research institutions in Korea. Many industries including the automobile, medical, shipping, mattress and construction industries need dynamic anthropometric data, such as range of motion, angle between body parts, spinal curvature, centre of pressure and so on. CONCLUSIONS: The Size Korea database-building process needs to be modified to take into account the needs of companies and industries.

Investigation of grip strength by various body postures and gender in Korean adults.

BACKGROUND: Grip strength is an objective measure of a person's hand functionality and upper limb strength. In Asia, there is a lack of normative data for grip strength among the population, especially in South Korea. OBJECTIVE: The objective of this study was to evaluate the grip strength in various body postures and gender in the adult South Korean population. METHODS: A total of 100 male and 64 female subjects participated in this study. Their grip strengths were measured using a standard adjustable Jamar handle dynamometer. RESULTS: The results showed that their grip strength differed statistically by gender, handedness, and posture. Their gender and right-hand length were the most significant predictors of their grip strength. The Asian population, including South Korea, showed a lower grip strength than the European and American populations in previous studies. CONCLUSIONS: The present study showed that the maximal isometric grip strength is affected by gender, handedness, posture, and population. Thus, gender-, population-, and posture-specific grip strength data are essential for clinical and industrial applications.

Orostachys japonicus induce p53-dependent cell cycle arrest through the MAPK signaling pathway in OVCAR-3 human ovarian cancer cells.

Orostachys japonicus (O. japonicus) is utilized as a traditional medicine for patients with various diseases. This study investigated the effect of the ethyl acetate fraction from O. japonicus extract (OJE) on the growth inhibition of OVCAR-3 human ovarian cancer cells demonstrated to inhibit cell growth and arrest the cell cycle in OVCAR-3 cells by blocking the sub-G1 phase and decreasing cyclin E1/CDK2 expression. Cell cycle arrest was connected to the increased expression of the cell cycle regulating factors p53 and p21. Apoptosis was initiated through the intrinsic pathway by up-regulating the expression of the Bcl-2/Bax ratio and down-regulating the expression of pro-caspase-3. Furthermore, OJE treatment elicited p-p38 activation and p-ERK1/2 inhibition. In conclusion, our results demonstrated that OJE reduced the growth of OVCAR-3 human ovarian cancer cells mediated by arrest of the cell cycle and regulation of MAPK signaling pathways.

In Situ Observation of Resistive Switching in an Asymmetric Graphene Oxide Bilayer Structure.

Graphene oxide decorated with oxygen functional groups is a promising candidate as an active layer in resistive switching devices due to its controllable physical-chemical properties, high flexibility, and transparency. However, the origin of conductive channels and their growth dynamics remain a major challenge. We use in situ transmission electron microscopy techniques to demonstrate that nanoscale graphene oxide sheets bonded with oxygen dynamically change their physical and chemical structures upon an applied electric field. Artificially engineered bilayer reduced graphene oxide films with asymmetric oxygen content exhibit nonvolatile write-once-read-many memory behaviors without experiencing the bubble destruction due to the efficient migration of oxygen ions. We clearly observe that a conductive graphitic channel with a conical shape evolves from the upper oxygen-rich region to the lower oxygen-poor region. These findings provide fundamental guidance for understanding the oxygen motions of oxygen-containing carbon materials for future carbon-based nanoelectronics.

Development of an Algorithm for Stroke Prediction: A National Health Insurance Database Study in Korea.

BACKGROUND: Stroke is the second leading cause of death worldwide and remains an important health burden both for the individuals and for the national healthcare systems. Potentially modifiable risk factors for stroke include hypertension, cardiac disease, diabetes, and dysregulation of glucose metabolism, atrial fibrillation, and lifestyle factors. OBJECTS: We aimed to derive a model equation for developing a stroke pre-diagnosis algorithm with the potentially modifiable risk factors. METHODS: We used logistic regression for model derivation, together with data from the database of the Korea National Health Insurance Service (NHIS). We reviewed the NHIS records of 500,000 enrollees. For the regression analysis, data regarding 367 stroke patients were selected. The control group consisted of 500 patients followed up for 2 consecutive years and with no history of stroke. RESULTS: We developed a logistic regression model based on information regarding several well-known modifiable risk factors. The developed model could correctly discriminate between normal subjects and stroke patients in 65% of cases. CONCLUSION: The model developed in the present study can be applied in the clinical setting to estimate the probability of stroke in a year and thus improve the stroke prevention strategies in high-risk patients. The approach used to develop the stroke prevention algorithm can be applied for developing similar models for the pre-diagnosis of other diseases.