Factors contributing to musculoskeletal disorders and neck-trunk posture among Shiraz university of medical sciences...

Musculoskeletal disorders are common among students exposed to prolonged sitting, and objective posture assessment is essential to clarify the contribution of ergonomic and environmental factors. This study aimed to evaluate factors associated with neck and trunk posture using quantitative image-based analysis. In this descriptive-analytical cross-sectional study, 25 students from Shiraz University of Medical Sciences were assessed. Neck and trunk angles were extracted from standardized lateral images using Digimizer software. Ergonomic compatibility between chairs and students' anthropometric characteristics was evaluated through a 12-item checklist. Musculoskeletal discomfort was assessed using the Cornell questionnaire, and mental workload was measured by NASA-TLX. General and task lighting indices and luminance were recorded. Correlation analyses and multiple linear regression were performed to determine predictors of posture angles. No significant associations were observed between demographic variables, lighting indices, mental workload, and neck or trunk angles (p > 0.05). In contrast, inappropriate seat height was associated with increased neck angle (p = 0.046), while insufficient seat width and lack of lower limb support were significantly related to increased trunk angle (p = 0.009 and p = 0.020). Trunk flexion was also associated with greater trunk angle (p = 0.035). Discomfort was most prominent in the neck and back regions. These findings indicate that postural deviations during study are primarily driven by chair design and anthropometric mismatch rather than lighting conditions or cognitive load.