Objective:To construct a structural equation model for neck work-related musculoskeletal disorders (WMSDs) in the footwear industry and analyze the mediating effect of fatigue in the model.Methods:From November 2018 to December 2019, stratified cluster sampling was adopted to select all the workers (3565 people) from 7 footwear enterprises in Fujian Province as the research subjects. The incidence of WMSDs, fatigue and work-related condition were investigated by using the Chinese version of the Musculoskeletal Disorders Questionnaire. A structural equation model of individual factors, work type, work posture, work organization factors, and fatigue on neck WMSDs was constructed to analyze the mediating effect of fatigue among them.Results:The incidence rate of WMSDs in the neck of footwear workers was 39.6% (1413/3565) , and the incidence rate of neck fatigue was 46.6% (1662/3565) .The final structural equation model was constructed with a χ2/ df of 9.927, a goodness-of-fit index of 0.961, an adjusted goodness-of-fit index of 0.946, and a root mean square error of approximation of 0.050. Except for the χ2/ df, all other fit indicators met the standard. Individual factors and work posture factors had a direct effect on neck WMSDs, with standardized path coefficients of 0.101 and 0.077, respectively ( P<0.05) . Individual factors, work type, work posture, and work organization had indirect effects on neck WMSDs through fatigue, the standardized path coefficients of indirect effects were 0.163, 0.090, 0.206, 0.105, respectively, and the standardized path coefficients of the total effect were 0.264, 0.090, 0.282, and 0.105 respectively ( P<0.05) . The indirect effects of individual factors and work posture factors on neck WMSDs through fatigue accounted for 61.74% and 73.05% of the total effects, respectively. The standardized path coefficient of fatigue on WMSDs was 0.689 ( P<0.001) , with the highest coefficient among all paths. Conclusion:Individual factors, work type, work posture, and work organization factors are important influencing factors in the occurrence and development of neck WMSDs in the footwear industry, and fatigue plays an important mediating role in them.

Objective To identify potential ergonomic risk factors of works and quickly assess their risks of developing work-related musculoskeletal disorders (WMSDs) in the medical staff. Methods A total of 188 medical staff were selected as the research objects using a two-stage random sampling method. The method for the identification of musculoskeletal stress factors (PLIBEL) was used to analyze the adverse ergonomic factors in the work process, and the rapid entire body assessment (REBA) was used to quickly assess the whole-body posture load. Results The PLIBEL assessment results showed that various adverse ergonomic factors affected different parts of the body during the work process of medical staff. Specifically, 18 adverse ergonomic factors were identified in the neck, shoulders, and upper back, while 10 adverse ergonomic factors were identified in the elbow, forearm, hand, and lower back. Rehabilitation therapists and nurses engaged in patient handling in general wards and medication preparation and blood collection were exposed to ≥35 adverse ergonomic factors. The REBA assessment showed that the REBA score was 3-12 points for medical staff during their work process. Rehabilitation therapists were classified as having an extremely high ergonomic risk. High-risk occupations included ward housekeeping nurses, surgery assistant nurses, operating-room instrument nurses, and surgeons. Medium-risk occupations included general ward nurses (medication preparation and blood collection, venipuncture/infusion, and patient handling), intensive care unit (ICU) nurses, internal medicine residents, and dentists. Low-risk occupations included administrative front-desk nurses, outpatient internal medicine physicians, and technicians/physicians in ultrasonography, laboratory medicine, physical examination, and occupational health departments. Conclusion Adverse ergonomic factors of medical staff predominantly affect the neck, shoulders, upper back, elbows, forearms, hands, and the lower back during the work process. Rehabilitation therapists, ward housekeeping nurses, ICU nurses, operating-room instrument nurses, and surgeons are high-risk groups for WMSDs. Attention should be paid to the management and control of adverse ergonomic factors for medical staff to prevent the occurrence of WMSDs.

Ergonomic Principle for the Prevention of Work-Related Musculoskeletal Disorders Part 1: General Principles (T/WSJD 14.1-2020) is the first guideline standard for the prevention of work-related musculoskeletal disorders provided to employers and occupational health technical service institutions in China, which covers ergonomic risk factors and their hazard definition, ergonomic prevention principles, risk assessment process, risk control process and risk evaluation principles. The standard specifically clarify the specific types of adverse ergonomic risk factors and control strategies and the standard process of systematic ergonomic risk assessment, providing implementation paths and practical guidance for eliminating/reducing adverse ergonomic risks and enhance workplace environments to prevent work-related musculoskeletal disorders. This paper interprets and analyzes the background of standard establishment, formulation process, fundamental basis, and main content, etc., to provide scientific and accurate technical support for enterprise managers, labours and technical personnel of occupational health institutions to optimize the use of this standard.

Objective:To evaluate the improvement effect of ergonomics in the assembly position of an automotive parts production company.Methods:From February to December 2023, the assembly positions and 8 operators of an automobile brake parts production company were selected as the research objects. The Swedish Ergonomic Hazard Identification Method and rapid upper limb assessment (RULA) were used to identify and evaluate the adverse ergonomic factors of work-related musculoskeletal disorders (WMSDs) in different parts of the body before and after the improvement. Through field investigation, observation and personnel interviews, three ergonomic problems were identified that need to be solved, namely, the height of the assembly table did not match the height of the operator, the storage space for small accessories was not set reasonably, and empty boxes were difficult to be placed. Technical improvements were made by designing an adjustable height assembly table, improving the layout of the workbench, and designing a mechanical pedal automation device. Statistical analysis was performed by t-test and paired rank sum test to evaluate the effectiveness of ergonomic improvements. Results:The operation of the assembly position could be divided into 13 actions, and the time to complete 1 cycle was (83.0±2.7) s. The Swedish Ergonomic Hazard Identification Method identified 28 adverse ergonomic factors of WMSDs in different parts before improvement, and 15 adverse ergonomic factors after improvement. Before ergonomics improvement, the RULA scores were 5 to 7 points, and the risk levels of 6 workers were Ⅳ (very high risk) and 2 workers were Ⅲ (moderate risk). After ergonomics improvement, the RULA score was 4 points, and the risk level was reduced to Ⅱ (low risk). Paired rank sum test results showed that there were statistically significant differences in upper arm, A-part (upper arm, lower arm and wrist) exertion and load, A-part muscle use, neck, total score, and risk level before and after improvement ( P<0.05). Per capita productivity of assembly post was (40.1±1.4) pieces/ (person·hour) before the improvement and (44.0±1.7) pieces/ (person·hour) after the improvement, the difference was statistically significant ( t=50.35, P<0.001) . Conclusion:The ergonomic improvement measures can reduce the adverse ergonomic factors in the assembly position of an automotive parts production company, reduce the risk of WMSDs, and improve the production efficiency.

Objective:To investigate the incidence of shoulder work-related musculoskeletal disorders (WMSDs) among occupational population in China, and to explore their intrinsic association with personal and work-related factors.Methods:In April 2024, 73497 valid questionnaires of the Chinese version of the Musculoskeletal Disorders Electronic Questionnaire were retrospectively analyzed from June 2018 to December 2023 in 22 provinces and 29 key industries in China, and the general information, occurrence of WMSDs and related risk factors of key occupational populations in different regions in China were collected. By using Chi-square test and confirmatory factor analysis, the relationship between shoulder fatigue and pain in key occupational groups and individual factors, work type, work posture and work organization was discussed, and the internal relationship was analyzed based on structural equation model.Results:Higher incidence of shoulder fatigue and pain were associated with female, lack of physical exercise, uncomfortable working posture and neck leaning forward ( P<0.05). Structural equation model analysis showed that work type, work posture and work organization were strongly correlated ( r=0.58, 0.55). Work organization and work type were strongly correlated with shoulder fatigue ( r=0.65) and moderately correlated with shoulder fatigue ( r=0.21). Shoulder fatigue was moderately associated with shoulder pain ( r=0.40). Individual factors, work type, work posture and shoulder fatigue could directly affect shoulder pain ( OR=0.07, -0.09, 0.17 and 0.40), and work type and work posture could also indirectly affect shoulder pain through shoulder fatigue ( OR=0.08, 0.03). Work organization only indirectly affected shoulder pain through shoulder fatigue ( OR=0.26) . Conclusion:The main influencing factor of shoulder pain is shoulder fatigue, followed by work posture and individual factors. Structural equation model can better reflect the complex relationship between work type, work posture and work organization and shoulder WMSDs. Improving work posture and work organization may be an effective way to control the influence of shoulder fatigue on shoulder pain.

Objective:To explore the structural equation model to explore the levels of work-related musculoskeletal disorders (WMSDs) and various risk factors in the feet and ankle of China's occupational population, providing scientific basis for for preventing WMSDs in feet and ankles.Methods:Data of 73497 national occupational epidemiological cases were selected from June 2018 to December 2023 used the Chinese version of the Electronic Questionnaire on Musculoskeletal Disorders. The adverse ergonomic factors and their source classification standard and confirmatory factor analysis were used to investigate foot and ankle WMSDs and their related risk factors (including individual factors, work organization, work posture, work type, fatigue, etc.) in key occupational groups in China, and structural equation model hypothesis, fitting, verification, and path and intermediary effect analysis were carried out. The model fit evaluation indexes included Chi-square specific degrees of freedom ( χ2/ df), gauge fit index (NFI), Tucker Lewis index (TLI), goodness of Fit index (GFI), adjusted Goodness of Fit index (AGFI) and approximate root mean square error (RMSEA) . Results:A total of 73497 occupational workers were surveyed, with local muscle fatigue and WMSDs incidence rates in the feet and ankles being 17.17% and 12.06%, respectively. The fitting index of the adjusted structural equation model basically meets the standard (GFI=1, AGFI=1, RMESA=0.042, NFI=0.716, TLI=0.663). The top three factors affecting feet and ankle WMSDs are feet and ankle muscle fatigue, work type, and work organization, with standardized path coefficients of 0.221, 0.105, and 0.095, respectively. The top two factors affecting feet and ankle muscle fatigue are work organization and work type, with standardized path coefficients of 0.548 and 0.383, respectively. Feet and ankle muscle fatigue, work type, work organization, and work posture have a direct effect on feet and ankle WMSDs, with effect values of 0.221, 0.105, 0.095, and 0.077, respectively. The organization and type of work can also have indirect effects through feet and ankle muscle fatigue, with effect values of 0.121 and 0.084, respectively.Conclusion:Feet and ankle muscle fatigue has a direct impact on WMSDs, and plays a mediating role between ankle and ankle WMSDs caused by work organization and work type. Feet and ankle muscle fatigue is an important pathway leading to feet and ankle WMSDs. It is recommended that employers and managers detect job fatigue early and take corresponding prevention and intervention measures, which can play a key role in preventing feet and ankle WMSDs.

Objective:To explore the structural relationship between WMSDs in the upper limbs and various risk factors in the occupational population in China, based on a large sample epidemiological survey and structural equation analysis, and to establish a structural equation model, so as to lay a foundation for the prevention and control of such diseases.Methods:The Chinese version of the Musculoskeletal Disorders Electronic Questionnaire was used to conduct a nationwide survey on the prevalence of WMSDs in the upper extremity. Six factors related to WMSDs in the upper extremity were extracted by the classification standard of adverse ergonomic factors and their source and confirmatory factor analysis, including work organization, work type, upper extremity work posture, individual factors, upper extremity fatigue and upper extremity WMSDs. The structural equation analysis was carried out and the structural equation model was established.Results:The incidence of WMSDs and fatigue in the upper limbs was 24.44% and 43.76%, respectively. The adjusted structural equation model fitting indicators were generally up to the standard (GFI=1.000, AGFI=1.000, RMSEA=0.043, NFI=0.808, TLI=0.784) . The four exogenous latent variables of work organization, work type, upper limb work posture and individual factors were correlated. There was a strong positive correlation between job type and upper limb work posture ( r=0.865) , a moderate positive correlation between work organization and job type and upper limb work posture ( r=0.570, 0.490) , and a weak negative correlation between individual factors and the other three exogenous latent variables. Upper limb work posture and individual factors had direct effects on upper limb WMSDs, and the effect coefficients were 0.10 and 0.06, respectively. Upper limb fatigue played a mediating role between work organization, work type, upper limb work posture and upper limb WMSDs. The effect coefficient was 0.46, and the composition ratios of indirect effects were 100.0%, 100.0%, and 38.3%, respectively. The direct path effect of upper limb work posture, individual factors and upper limb WMSDs was weaker than the mediating path through upper limb fatigue. Conclusion:When carrying out the prevention and control of upper limbWMSDs, it is necessary to comprehensively consider the pathogenesis path of upper limb muscle fatigue and upper limb WMSDs caused by work organization, work type, and upper limb work posture, so as to provide theoretical reference for improving the prevention and control level of such diseases.

Objective:To construct a structural equation model for neck work-related musculoskeletal disorders (WMSDs) in the footwear industry and analyze the mediating effect of fatigue in the model.Methods:From November 2018 to December 2019, stratified cluster sampling was adopted to select all the workers (3565 people) from 7 footwear enterprises in Fujian Province as the research subjects. The incidence of WMSDs, fatigue and work-related condition were investigated by using the Chinese version of the Musculoskeletal Disorders Questionnaire. A structural equation model of individual factors, work type, work posture, work organization factors, and fatigue on neck WMSDs was constructed to analyze the mediating effect of fatigue among them.Results:The incidence rate of WMSDs in the neck of footwear workers was 39.6% (1413/3565) , and the incidence rate of neck fatigue was 46.6% (1662/3565) .The final structural equation model was constructed with a χ2/ df of 9.927, a goodness-of-fit index of 0.961, an adjusted goodness-of-fit index of 0.946, and a root mean square error of approximation of 0.050. Except for the χ2/ df, all other fit indicators met the standard. Individual factors and work posture factors had a direct effect on neck WMSDs, with standardized path coefficients of 0.101 and 0.077, respectively ( P<0.05) . Individual factors, work type, work posture, and work organization had indirect effects on neck WMSDs through fatigue, the standardized path coefficients of indirect effects were 0.163, 0.090, 0.206, 0.105, respectively, and the standardized path coefficients of the total effect were 0.264, 0.090, 0.282, and 0.105 respectively ( P<0.05) . The indirect effects of individual factors and work posture factors on neck WMSDs through fatigue accounted for 61.74% and 73.05% of the total effects, respectively. The standardized path coefficient of fatigue on WMSDs was 0.689 ( P<0.001) , with the highest coefficient among all paths. Conclusion:Individual factors, work type, work posture, and work organization factors are important influencing factors in the occurrence and development of neck WMSDs in the footwear industry, and fatigue plays an important mediating role in them.

Ergonomic Principle for the Prevention of Work-Related Musculoskeletal Disorders Part 1: General Principles (T/WSJD 14.1-2020) is the first guideline standard for the prevention of work-related musculoskeletal disorders provided to employers and occupational health technical service institutions in China, which covers ergonomic risk factors and their hazard definition, ergonomic prevention principles, risk assessment process, risk control process and risk evaluation principles. The standard specifically clarify the specific types of adverse ergonomic risk factors and control strategies and the standard process of systematic ergonomic risk assessment, providing implementation paths and practical guidance for eliminating/reducing adverse ergonomic risks and enhance workplace environments to prevent work-related musculoskeletal disorders. This paper interprets and analyzes the background of standard establishment, formulation process, fundamental basis, and main content, etc., to provide scientific and accurate technical support for enterprise managers, labours and technical personnel of occupational health institutions to optimize the use of this standard.

Objective:To evaluate the improvement effect of ergonomics in the assembly position of an automotive parts production company.Methods:From February to December 2023, the assembly positions and 8 operators of an automobile brake parts production company were selected as the research objects. The Swedish Ergonomic Hazard Identification Method and rapid upper limb assessment (RULA) were used to identify and evaluate the adverse ergonomic factors of work-related musculoskeletal disorders (WMSDs) in different parts of the body before and after the improvement. Through field investigation, observation and personnel interviews, three ergonomic problems were identified that need to be solved, namely, the height of the assembly table did not match the height of the operator, the storage space for small accessories was not set reasonably, and empty boxes were difficult to be placed. Technical improvements were made by designing an adjustable height assembly table, improving the layout of the workbench, and designing a mechanical pedal automation device. Statistical analysis was performed by t-test and paired rank sum test to evaluate the effectiveness of ergonomic improvements. Results:The operation of the assembly position could be divided into 13 actions, and the time to complete 1 cycle was (83.0±2.7) s. The Swedish Ergonomic Hazard Identification Method identified 28 adverse ergonomic factors of WMSDs in different parts before improvement, and 15 adverse ergonomic factors after improvement. Before ergonomics improvement, the RULA scores were 5 to 7 points, and the risk levels of 6 workers were Ⅳ (very high risk) and 2 workers were Ⅲ (moderate risk). After ergonomics improvement, the RULA score was 4 points, and the risk level was reduced to Ⅱ (low risk). Paired rank sum test results showed that there were statistically significant differences in upper arm, A-part (upper arm, lower arm and wrist) exertion and load, A-part muscle use, neck, total score, and risk level before and after improvement ( P<0.05). Per capita productivity of assembly post was (40.1±1.4) pieces/ (person·hour) before the improvement and (44.0±1.7) pieces/ (person·hour) after the improvement, the difference was statistically significant ( t=50.35, P<0.001) . Conclusion:The ergonomic improvement measures can reduce the adverse ergonomic factors in the assembly position of an automotive parts production company, reduce the risk of WMSDs, and improve the production efficiency.