Shoulder and Spinal Kinematics During Spiking in Male High School Volleyball Players With Subacromial Impingement Syndrome

Background and Purpose: Volleyball players have a high prevalence of subacromial impingement syndrome (SAIS). Scapular dyskinesis (SD) is one of the contributing factors to SAIS. An increase in thoracic kyphosis angle and limited range of trunk extension may affect the scapular movement control and lead to SD. For volleyball spiking, forcefully overhead shoulder movement and trunk rotation and extension are required. When trunk mobility is limited, it may lead to an increased loading on the shoulder joint. Shoulder-hip separation (S-HSA) is used to assess the kinetic transferring capacity of the pelvic and trunk chain. When the S-HSA angle decreases, the load on the upper extremities may be raised for compensation. However, the control of spinal and shoulder movements during spiking was less addressed. Therefore, this study aims to compare the kinematics of trunk, pelvis and shoulder during spiking between elite high school volleyball players with and without SAIS. Methods: Recruit twelve elite high school volleyball players, with six in the SAIS group and six in the health group. A motion capture system was employed to assess the trunk, pelvic and shoulder kinematics during spiking. The maximal voluntary isometric contraction (MVIC) in both the shoulder and trunk was assessed. Differences of kinematics and strength between two groups were examined by Mann-Whitney U Test. Results: Volleyball players with SAIS during spiking exhibit limited thoracic (-33.9° ± 17° vs. -55.1° ± 5.3°, p = 0.041) and pelvic (-24.9° ± 15° vs. -49.5° ± 10.3°, p = 0.015) ipsilateral rotation compared to the healthy group, while shoulder motion is similar in both groups. The serratus anterior muscle strength in the SAIS group is less than the healthy group (20.5 ± 1.7 kg vs. 30.7 ± 8 kg, p = 0.041). Conclusions: In SAIS group during spiking, limited thoracic and pelvic ROM may increase the load on the shoulder. Clinical Relevance: In the future, advise volleyball players with SAIS to include scapular stabilization and rotator cuff exercises, along with thoracic spine stretching and core muscle strengthening.