Abstract
Increased use of smartphones can cause abnormal alignment of head and neck, resulting in forward head posture (FHP). This can lead to change in the structures and function of the cervical vertebrae. The purpose of this study was to determine the impact on deep neck flexor muscles, proprioception, vestibular function, and balance of subjects with induced FHP by using smartphone. Twenty-two healthy persons were randomly divided into two groups. The FHP group maintained a craniovertebral angle (CVA) of <49° and a normal head posture group maintained a CVA of >50° watching the smartphone for 40 min. We measured the area of the longus colli and longus capitis muscles, cervical joint position sense, Romberg test, subjective visual vertical test, and subjective visual horizontal test. There was no significant difference in the deep neck flexor muscles, vestibular function, and static balance between the groups. However, there was a significant difference in the cervical proprioception (P<0.05). Proprioception may be considered to be the most influential factor in induced FHP by smartphone viewing.