Thesis : Submitted for Fulfillment of requirements of the master's degree in Physical Therapy for Basic Sciences Department

Background: The use of mobile devices, such as the smartphone, has been associated with shoulder pain and imbalance in the shoulder muscles as a result of muscle stress. The aim of this study was to investigate the effect of using a smartphone on pain in the upper back, the scapular muscles, and the strength of the scapular muscles (the lower fibers of the trapezius muscle, And the rhomboid major and minor muscles) for healthy people,
Methods and Methods: This study was a cross-sectional study; On a sample of eighty normal adults between the ages of 20 and 30 years, with the condition that the right hand is dominant for all people for this study. People must have at least 6 months of experience using a smartphone. The people were divided into two groups: Group A (which uses the smartphone less than 4 hours a day) and Group B (which uses the smartphone more than 4 hours a day). The assessment was for upper back pain or fatigue and strength.