Effects of smartphone screen viewing duration and body position on head and neck posture in elementary school children.

BACKGROUND Electronic media have become integral parts of modern life, in which prolonged screen viewing time (SVT) by children is nearly unavoidable. Prolonged use of smartphones could lead to musculoskeletal problems. OBJECTIVES To investigate the effect of SVT on head and neck posture during and after using smartphones for various periods of time in either standing or sitting postures. METHODS This observational study included 34 male children aged 5-12 years who were assigned to one of two groups based on average smartphone use duration per day: group A comprised 18 children averaging > 4 hours per day (h/day) of smartphone use, and group B comprised 16 children with < 4 h/day of smartphone use. The children's postures were photographed in standing and sitting positions while using a smartphone and 30 min after ceasing smartphone use. The head flexion, neck flexion, gaze, and craniocervical angles were measured using the software program Kinovea. RESULTS Significant increases were found in head flexion, neck flexion, and gaze angles. Furthermore, both groups saw a significant decrease in craniocervical angle when sitting compared to when standing, both during and 30 min after smartphone use. The head flexion, neck flexion, and gaze angles of group A were significantly higher than those of group B, and the craniocervical angle of group A was significantly lower than that of group B in both postures (p< 0.05). CONCLUSION SVT is associated with increased neck and head flexion posture in children, especially in a sitting position.