Comparison of Isometric Strength and Functional Stability of Shoulder Girdle Muscles in Volleyball Women Players with and without Scapular Dyskinesia

Introduction: Shoulder dyskinesia is common among athletes with overhead throws and can make athletes susceptible to shoulder injuries. The purpose of this study was to compare the isometric strength and functional stability of shoulder girdle muscles in volleyball women Players with and without scapular dyskinesia. Methods: In this descriptive-comparative study, 12 women volleyball players with scapular dyskinesia and 12 women volleyball players without scapular dyskinesia between 18 and 30 years were purposefully selected and compared. Kibler shoulder lateral slip test was used to assess shoulder movement disorder. A manual dynamometer was used to measure the maximal isometric strength of the shoulder muscles and the Y balance board was used to measure the functional stability of the upper extremity. Data were analyzed by SPSS 21 software. Results: There was a significant difference between the maximum isometric strength of infraspinatus (P = 0.001), sub-scapula (P = 0.004), upper trapezoid (P = 0.001), lower trapezoid (P = 0.001) and serratus anterior (P=0.003) was present in individuals with and without dyskinesia. Also, the results of upper extremity functional stability test showed that in the superior-lateral (P = 0.04), middle (P = 0.009) and composite (P = 0.01) areas between athletes 'superior hand performance with scapular dyskinesia with athletes' superior hand performance. Conclusions: In volleyball players with scapular dyskinesia, scapular stabilizers, including the dentate muscles and the inferior trapezius, were weaker than others. Also, functional stability in the shoulder of volleyball players with scapular dyskinesia was lower than in healthy subjects. Considering the association between decreased strength of shoulder girdle movements with dyskinesia, strengthening of shoulder girdle muscles, especially anterior and lower trapezius muscles, is recommended in in with scapular dyskinesia.