Effect of Scapular Movement Impairment on Functional Stability of Shoulder Girdle and Scapulohumeral Rhythm in Elite male Volleyball Players
Authors:   Department of Corrective Exercises and Sports Injuries, Faculty of Physical Education and Sport Sciences, University of Guilan, Rasht, Iran., Pashaei Zahra , Daneshmandi Hassan ,   Department of Corrective Exercises and Sports Injuries, Faculty of Physical Education and Sport Sciences, University of Guilan, Rasht, Iran., Norasteh Aliasghar ,   Department of Corrective Exercises and Sports Injuries, Faculty of Physical Education and Sport Sciences, University of Guilan, Rasht, Iran., Fatahi Ali ,   Department of Sport Biomechanics, Faculty of Physical Education and Sport Sciences, Central Tehran Branch, Islamic Azad university, Tehran, Iran.
Published: September 2022

Background and Aims The shoulder girdle is at higher risk of injury in overhead sports like volleyball. Repeated movements with high speed and power can cause changes in scapular position and lead to shoulder girdle dysfunction. This study aims to assess the effect of scapular movement impairment on functional stability of the shoulder girdle and the scapulohumeral rhythm in elite male volleyball players Methods In this descriptive-comparative study, 80 male volleyball players aged 18-35 years including 40 with scapular downward rotation syndrome (SDRS) (age=22±2.8 years, weight=82.50±1.3 kg, and height=193±3.2 cm) and 40 with scapular abduction syndrome (SAS) (age=24±2.1 years, weight=81.40±1.3 kg, and height=192±2.9 cm) participated who were selected purposefully. They underwent the scapular dyskinesis test and Kibler’s shoulder lateral slip test. The scapulohumeral rhythm was measured at four positions (0, 45°, 90°, and 135°) using two inclinometers. The Y-balance test-upper quarter (YBT-UQ), seated medicine ball throw test (SMBT), and closed kinetic chain upper extremity stability test (CKCUEST) were used to measure the functional stability of the upper extremity. Shapiro-Wilk test was used for examining the normality of data distribution, independent t-test was used to compare the differences between groups. Results There was a significant difference in the scapulohumeral rhythm at 45° (P=0.001), 90° (P=0.001), and 135° (P=0.001) between the two groups (Mean difference= 18.27, 21.27, and 27.87, respectively), where the SDRS group had lower scapular upward rotation than the SAS group. The results of YBT-UQ showed that the superior-lateral reach (P=0.001) and composite (P=0.001) scores of the dominant hand were significantly different between the two groups (Mean difference = 9.37 and 10.41, respectively), where the SDRS group had lower scores than the SAS group. No significant difference was found in the medial (P= 0.223) and inferior-lateral (P= 0.111) reach scores. Moreover, the results showed no significant difference between the groups in the SMBT (P=0.124) and CKCUEST (P=0.875) scores. Conclusion The occurrence of scapular movement impairment affects the YBT-UQ score and leads to scapulohumeral rhythm disturbance in volleyball players. Even if the activity is stopped, the ideal and optimal alignment will not be created unless efforts are made to improve the movement pattern.