Background:Scapular muscle endurance and core endurance reportedly may influence shoulder injury risk. Hence, the present study aimed to analyze the difference between healthy subjects and those with chronic shoulder pain with regard to scapular endurance, core endurance and pain level. Additionally to explore the relationship between measures of scapular endurance, core endurance and pain level. Subjects: Sixty subject of both sexes with mean age 25.66 ± 2.30 years were participated in this study. They weredivided into two equal groups; the control group and the study group who suffering from chronic sub acromial impingement syndrome (SAIS). Methods: Endurance of the serratus anterior and trapezius muscles was assessed using the scapular muscle endurance (SME) test. Modified Sorensen test, trunk flexor endurance test and endurance of lateral core muscles were conducted to assess the core endurance. The pain level was assessed by shoulder pain and disability index (SPADI). Results: There were significant declines of the values of Scapular muscle endurance test and all functional core endurance test in experimental group compared by control group. Additionally, Scapular muscle endurance test scores showed a correlation with the modified Sorensen test, trunk flexor endurance test,lateral endurance on affected side and pain level (r = 0.859, p = 0.0001; r = 0.845, p = 0.0001 ; r = 0.824, p = 0.0001 ; r =- 0.668, p =0.0001) respectively. No significant correlation was found between scapular muscle endurance test and lateral endurance test for non-affected side (p >0.05). Conclusion: Scapular endurance and core endurance deficiency was found in patient with SAIS. There appears to be a link between the scapular muscle endurance and all core test except non-affected lateral core endurance test.
