Association Between Long-Duration Sitting with Forward Trunk Flexion During Mobile Device Use and Its Effects on Musculoskeletal Health, Neuroendocrine Function, and Psychological Well-being: Implications for Physiotherapy Intervention

Abstract Background: Prolonged sitting with forward trunk flexion during mobile device use has emerged as a ubiquitous occupational and leisure-time behavior in contemporary society, with global implications for musculoskeletal health, metabolic function, and psychological well-being. The biomechanical consequences of sustained sitting posture, coupled with device-related behavioral patterns, create a multisystem physiological disruption affecting approximately 71% of the global population. Objective: This narrative review synthesizes contemporary evidence examining the musculoskeletal, neuroendocrine, and psychological consequences of prolonged sitting with forward trunk flexion during mobile device use, with emphasis on physiotherapy-based intervention strategies. Methods: Systematic literature review of peer-reviewed publications (2015-2025) examining sitting posture biomechanics, sedentary behavior physiology, mobile device use effects, stress hormone regulation, sleep disturbance, and physiotherapy intervention efficacy. Analysis included biomechanical modeling studies, prospective longitudinal investigations, and randomized controlled trials. Key Findings: Prolonged sitting maintains lumbar spine in 70% of maximum forward flexion, increasing intradiscal pressure by 270-290%, and precipitating disc degeneration rates of 31% in chronic users versus 8% in controls. Sedentary behavior exceeding 6 hours daily produces insulin resistance, metabolic dysfunction, visceral adiposity accumulation (25-48% increase), elevated cortisol dysregulation, reduced heart rate variability (RMSSD<50 ms), and increased anxiety and depression (GAD-7 scores elevated 33%, PHQ-9 scores 32% higher). Smartphone addiction behaviors correlate significantly with forward head posture, thoracic hyperkyphosis, and behavioral dependence patterns (63.3% addiction prevalence, 8.7 hours weekend usage). Comprehensive physiotherapy intervention incorporating postural re-education, movement re-education, ergonomic modification, diaphragmatic breathing training, and structured activity breaks demonstrate significant efficacy in reversing musculoskeletal dysfunction, normalizing metabolic markers, and improving psychological well-being within 8-12 weeks. Clinical Implications: Physiotherapy should incorporate routine assessment of sittingrelated postural dysfunction, integrate sedentary behavior modification into treatment protocols, and develop evidence-based lifestyle intervention strategies addressing mechanical, metabolic, and psychological dimensions simultaneously. Conclusion: The convergence of musculoskeletal strain, metabolic dysregulation, stress hormone dysfunction, and psychological disturbance in chronic mobile device users necessitates integrated, multimodal physiotherapy intervention. Future research priorities include longitudinal dose response investigations, comparative effectiveness trials, and development of technology-integrated intervention tools