Introduction: Forward Head Posture (FHP) is one of the most common postural disorders which may cause some changes in motor control of cervical muscles. Although there is evidence for an association between forward head posture and the development of shoulder pain, few studies consider the issue how this relationship might be during dynamic activity. Therefore, the purpose of this study was to assess electromyography activity of selected cervical and trunk muscle in subjects with and without forward head posture during gait. Methodology: In this study 20 boys (10-15) years old, included (10 person with forward head posture and 10 person with normal head posture) were selected from students of Hamadan city. At first Craniovertebral angle of subjects were measured by goniometer. The subject that their Craniovertebral angle was in 42/7±1/5 was considered as forward head group. EMG activity of sternocleidomastoid, upper trapezius and lower trapezius, serratus anterior and cervical erector spine were recorded during gait using surface electromyography. To normalize the results from the EMG, the maximum voluntary isometric contraction (MVC) was used. Results: Independent t-test was used to compare EMG activity of each muscle in two groups . Statistical analysis displayed significant increases in right upper trapezius muscle activity (p = 0/035) in subject with normal head posture. In other muscle activity of other muscle, there was no significant different between two groups (p > 0/05 ). Conclusion: The normalized value of right upper trapezius muscle during gait in subject with normal head posture is farther than subject with forward head posture. The result of this study provides support for the clinical theory that forward head posture can alter muscle activity during dynamic activity.
