Relationships between physical effort, cognitive workload, and musculoskeletal symptom burden in lean manufacturing environments: Evidence from Moroccan industrial organizations

BackgroundMusculoskeletal symptoms remain an occupational health concern in manufacturing, where physical and cognitive demands may coexist. In Lean manufacturing environments, evidence regarding their associations with musculoskeletal symptom burden remains limited.ObjectiveThis study examined the relationships between perceived physical effort, cognitive workload, and musculoskeletal symptom burden among employees working in Moroccan industrial organizations implementing Lean manufacturing practices.MethodsA cross-sectional survey was conducted among 150 employees from Moroccan industrial organizations implementing Lean manufacturing practices. Musculoskeletal symptoms were assessed using the Standardized Nordic Musculoskeletal Questionnaire, perceived physical effort using the Borg Category-Ratio Scale (CR10), and cognitive workload using an adapted NASA Task Load Index (NASA-TLX). Musculoskeletal symptom burden was defined as the number of body regions with reported symptoms during the previous 12 months. Descriptive statistics, Pearson correlations, multivariable Poisson regression adjusted for sex, age group, industry, occupational position, and seniority were performed, along with complementary group comparisons.ResultsPerceived physical effort was independently associated with musculoskeletal symptom burden, whereas no statistically significant independent association was detected for cognitive workload. Musculoskeletal symptom burden differed across occupational positions. Industry-related findings were less consistent across analyses, while no statistically significant association or group differences were observed according to seniority.ConclusionsPerceived physical effort showed a consistent association with musculoskeletal symptom burden in the investigated Lean manufacturing environments, whereas the association with cognitive workload was not statistically significant. The findings support the relevance of considering physical workload and occupational context when evaluating musculoskeletal health and integrating ergonomic considerations into Lean continuous improvement activities.