Evaluating the Effectiveness of Workplace Ergonomic Interventions in Reducing Lower Back Pain among Manufacturing Employees

Thesis Abstract

Lower back pain (LBP) among manufacturing employees remains a prevalent occupational health concern, significantly impacting worker productivity, absenteeism, and healthcare costs. Despite the implementation of various ergonomic interventions, the evidence regarding their effectiveness in reducing LBP within manufacturing settings remains inconsistent and underexplored. This study aims to evaluate the effectiveness of workplace ergonomic interventions in mitigating lower back pain among manufacturing employees, with specific objectives to assess changes in perceived LBP severity, functional ability, and ergonomic compliance post-intervention, and to identify socioeconomic and psychosocial factors influencing intervention outcomes. Employing a mixed-methods research design, the study integrates quantitative and qualitative approaches to comprehensively examine the interventions' impacts. The quantitative component adopts a quasi-experimental, pretest-posttest control group design involving a sample of 200 manufacturing employees from a major automotive assembly plant, with 100 participants assigned to the intervention group and 100 to the control group via stratified random sampling. Data collection instruments include a validated Nordic Musculoskeletal Questionnaire (NMQ) for LBP assessment, the Oswestry Disability Index (ODI) for functional disability, and an ergonomic compliance checklist. Qualitative data are gathered through semi-structured interviews with 20 employees and safety managers to explore perceptions, facilitators, and barriers to ergonomic practice adherence. Data analysis involves descriptive statistics to delineate participant characteristics, paired t-tests and ANCOVA to evaluate differences in LBP severity and functional ability between pre- and post-intervention periods, and multiple regression analysis to identify predictors of intervention success. Thematic analysis of qualitative transcripts offers in-depth insights into contextual factors influencing ergonomic intervention outcomes. The theoretical framework integrates the Health Belief Model and the Job Demands-Resources Model to interpret behavioral and organizational factors affecting ergonomic compliance and effectiveness. The anticipated findings suggest that ergonomic interventions, including adjustable workstations, ergonomic training, and ergonomic assessment feedback, will lead to statistically significant reductions in LBP severity and disability scores among the intervention group compared to controls. Qualitative insights are expected to reveal that organizational support, ergonomic awareness, and employee engagement are critical determinants of intervention adherence and success. The study aims to fill existing gaps by providing rigorous, context-specific evidence on ergonomic intervention efficacy in manufacturing settings and elucidating psychosocial and organizational moderators. This research contributes substantially to occupational health knowledge by validating intervention strategies that can inform policy and best practices within manufacturing industries. It underscores the importance of multi-faceted approaches that combine ergonomic redesign with behavioral change initiatives. The main conclusions emphasize that tailored ergonomic interventions, supported by organizational commitment and employee participation, effectively reduce LBP and improve work-related functional outcomes. Recommendations include the adoption of comprehensive ergonomic programs, periodic ergonomic assessments, targeted employee education, and fostering a safety culture to sustain health benefits. Suggestions for future research highlight the need for longitudinal studies to evaluate the durability of ergonomic interventions and to explore their cost-effectiveness in diverse manufacturing contexts.