Abstract
Background: Physical condition, workload, and fatigue are important considerations among workers engaged in repetitive and physically demanding activities. However, practical mobile-based systems integrating these indicators into a single assessment workflow remain limited. Objectives: This study aimed to develop and preliminarily evaluate a mobile-based assessment system for BMI, perceived workload, and subjective fatigue and examine their associations among industrial workers. Methods: A research and development design using the ADDIE framework was followed by a cross-sectional evaluation of 77 industrial workers recruited through convenience sampling. The application assessed BMI, perceived workload, and subjective fatigue using the Fatigue Assessment Scale. Associations among variables were examined using Pearson's chi-square test and Cramér's V. Results: The application demonstrated favorable preliminary expert and user evaluations, with scores of 87.11% for material validity, 92.90% for media validity, and 91.58% for user practicality. Among 77 workers, 51.9% reported moderate workload and 35.1% had high fatigue. Perceived workload was significantly associated with subjective fatigue, whereas BMI was not. High fatigue was more prevalent among workers with high workload (56.0%) than low workload (8.3%) and among those with obesity (62.5%) than normal BMI (25.0%). Conclusion: The developed mobile-based system provides an integrated digital workflow for assessing BMI, perceived workload, and subjective fatigue and demonstrated favorable preliminary expert and user evaluations. The observed distribution of fatigue across workload and BMI categories warrants further investigation using larger samples, longitudinal designs, objective physiological measures, and standardized usability assessments.