Changes in the range of head flexion rotation and neck muscle activity after prolonged use of a smartphone

Abstract

Text-neck has been the main health concern among smartphone users. The current study explored a potential association between the duration of static head flexion posture during smartphone use and the viscoelastic changes of the cervical spine passive tissues. Ten participants conducted a smartphone task for 30 minutes, and their full head flexion angle and the neck muscle activity during a head extension motion were quantified before, in the middle, and after the 30-min task. Participants reported higher neck discomfort ratings after smartphone use, and the neck muscle activity showed an increasing trend over time. However, no significant difference was found in the muscle activity level between the three time levels. Full head flexion angle also did not vary significantly over time (p > 0.05). Study results imply the reduction of tissue stiffness during smartphone use, but warrant further research with a more sensitive evaluation method.