Background: Forward head posture (FHP) is a postural alignment of the cervical vertebrae that leads to increased gravitational load on cervical segmental motions. The overhead arm lift test assesses the ability to actively dissociate and control low cervical flexion and move the shoulders through overhead flexion.
Objects: The purpose of this study was to explore muscle activities in the upper trapezius (UT), serratus anterior (SA), sternocleidomastoid (SCM), and lower trapezius (LT) alongside changes in head position during the overhead arm lift test in individuals with FHP.
Methods: Fifteen subjects with forward head posture and fifteen subjects with normal subjcects were enrolled in this study. The patients performed the overhead arm lift test, and muscle activities of the UT, SCM, SA, and LT were measured using surface electromyography and by evaluating changes in head position. Independent t-tests were used to detect significant differences between the two groups and Cohen’s d was calculated to measure the size of the mean difference between the groups.
Results: The FHP group demonstrated significantly increased muscle activity of the UT (32.46±7.64), SCM (12.79±4.01), and LT (45.65±10.52) and significantly decreased activity in the SA (26.65±6.15) than the normal group. The change in head position was significantly higher in the FHP group (6.66±2.08) than the normal group. Effect sizes for all parameters assessed were large between the two groups.
Conclusion: The subjects with excessive FHP displayed were unable to fix their heads in position during the overhead arm lift test. The overhead arm lift test can thus be used in clinical settings to confirm control of the neck in these subjects.

Abstract
 Introduction
 Methods
  Participants
  Measurement of FHP
  Surface electromyography (EMG)
  Overhead arm lift test
  Statistical analysis
 Results
  Comparison of head position
  Comparison of the muscle activities
 Discussion
 Conclusion
 References

• Tae-ho Kim(Dept. of Physical Therapy, College of Rehabilitation Science, Daegu University)
• Byoung-ha Hwang(Dept. of Physical Therapy, College of Rehabilitation Science, Daegu University) Corresponding author