To determine the synthetic risk factors of musculoskeletal disorders, and to examine effect on musculoskeletal symptoms of physical work intensity and change of work intensity.

Self-administered questionnaraire survey was conducted on 588 motor engine assembly workers, in Chanwon, Kyungnam provance, Korea, from April 1 to May 31, 2003. The contents of the questionnaire investigation included general characteristic items, workrelated characteristic items, presence of musculoskeletal symptoms, ergonomic risk factors items, job stress items, current physical work intensity and changes of work intensity items. The results underwent statistical analysis with frequency test, t-test, and logistic regression. The statistical significance level was 0.05, and SAS(v8.1) was used.

Multiple logistic regression analysis was used to examine the relationship between risk factors and musculoskeletal symptoms. From the results, significant variables were high Quick Exposure Check (QEC) score, high job demand control, physical work intensity, change of work intensity.

Among the known risk factors of musculoskeletal disorders, the outbreak of musculoskeletal symptoms was confirmed to be correlated with age, tenure, ergonomic risk factors, and job stress. Physical work intensity and the changes of work intensity were also related to musculoskeletal symptoms.