Effects of the Kinetic Chain Management Approach on Pain and Performance in Volleyball Athletes With Scapular Dyskinesia: A Randomized Controlled Trial

Volleyball is a highly technical sport which involved powerful overhead movements performed repetitively. Shoulder injuries is the third-most commonly injured body part in volleyball, with the majority resulting from chronic overuse. Abnormal scapular motions and positions relative to the thorax have been linked to various shoulder pathologies, including subacromial impingement, rotator cuff tears, and glenohumeral inferior instability. Also, Muscular imbalances around the shoulder complex could lead to dyskinesis and resulting in shoulder joint injuries (e.g. instability and impingement).

The concept of "kinetic chain" is coordinated sequencing of the segments. Sequential activation of the LE, pelvis and trunk muscles is required to facilitate the forces to be transferred appropriately from these body segments to the UE.

One previous study have identified risk factors for volleyball-related shoulder pain and dysfunction. They found volleyball athletes who demonstrated core instability would show greater relevance to SICK scapula, and they also more likely to report a history of shoulder problems. Another study also have reviewed that 49% athletes with posterior-superior labral tears showed either decreased hip rotators flexibility or decreased hip abductors strength. Consequently, the deficits in kinetic chain segments would resulted in scapula dyskinesis, even lead to shoulder girdle dysfunction or injury.

Therefore, the modern training programs for athletes, especially in overhead players, should combine kinetic chain exercises to improve upper- and lower body core strength, sport-specific strength, performance, and prevent injury occurrence or recurrence.

In consideration of no randomized controlled trials (RCTs) have been performed to determine whether kinetic chain exercise would be more effective to conventional scapula training for patients with secondary shoulder impingement. The purpose of the study is to investigate the effects of kinetic chain management approach (KC) and conventional training of scapula dyskinesis (CT) in volleyball athletes with scapular dyskinesia. The investigators hypothesized that KC group would be more effective in self-reported pain, and their scapula would become more stable during movement task (arm-lifting and spiking) after a 4-week training program than CT group.