[Study on the mediating effect of fatigue on neck WMSDs in the footwear industry]

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 χ(2)/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 χ(2)/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.