The neck flexion angle increases with difficulty of tasks performed on a smartphone

BackgroundIn recent years, smartphones have become popular worldwide and are used in daily life. Consequently, the musculoskeletal discomfort associated with smartphone use has become a problem. Neck pain, also known as text neck syndrome, develops due to neck flexion posture.ObjectiveThe present study determined how the neck flexion angle increases with the difficulty of a task performed on a smartphone. This study also assessed the factors associated with the neck flexion angle while using a smartphone.MethodsSubjects were 24 healthy adults. Using the VICON motion analysis system, neck flexion angles while using a smartphone were measured under three conditions: normal standing (control), standing while watching a video (watching), and standing while typing (typing).ResultsThe neck flexion angles (mean ± standard deviation) were 0.71 ± 7.05° for the control, 26.02 ± 6.28° for watching, and 30.52 ± 7.83° for typing, indicating a significant difference (p < 0.001). Significant differences were also observed between the control-watching, control-typing, and watching-typing conditions (p < 0.001). A correlation was found between average daily smartphone usage time and the neck flexion angle of typing (r = 0.531, p = 0.008).ConclusionsThe neck flexion angle increased with the difficulty of the task performed on the smartphone. People with a longer average daily smartphone usage time were more likely to adopt a neck flexion posture while using their smartphones than those with a shorter average usage.