In elite volleyball players, repetitive spiking unevenly burdens the (DOM) dominant shoulder, which can result in adaptations or injuries. Spiking consists of the cocking, acceleration and deceleration phases. In the cocking phase, the dominant arm abducts and externally rotates in preparation for forceful adduction and internal rotation in the acceleration phase. Finally, the hand decelerates and stops at the player’s side. Elevated spiking speed (SS) is a competitive advantage, and glenohumeral joint or scapular changes associated with SS have not been previously investigated. In former studies, the DOM shoulder showed increased external rotation gain (ERG), glenohumeral internal rotation deficit (GIRD), glenohumeral joint imbalance, scapular dyskinesis and infraspinatus atrophy (IA) when compared to the non-dominant (NDOM) shoulder.
The aim of this study is to test the following hypotheses: (1) shoulder morphology differs between the DOM and NDOM sides, players with and without shoulder pain history (SPH), and players with and without IA; (2) SS is reduced in players with SPH and IA; (3) SS is associated with shoulder morphology; (4) demographic characteristics correlate with specific shoulder morphologies; and (5) SS and shoulder morphology is effected by team role.
Twenty-two male volleyball players from the Cypriot championship answered questions about their demographics, SPH, volleyball experience and training. After recording the BMI and inspecting for scapulae winging and IA, the researchers performed a Hawkins-Kennedy, Jobe, palm-up, infraspinatus and lift-off tests on the DOM and NDOM shoulders of participants. The mechanics of Hawkins-Kennedy and Jobe tests are below in Table 1.
|Hawkins-Kennedy||Shoulder is flexed at 90º anteriorly; elbow is flexed at 90º medially.||Supporting the elbow, examiner exerts a downward force on the forearm without patient resistance||Non-specific shoulder impingement|
|Jobe||Shoulder is abducted at 90º and internally rotated; elbow is extended.||Examiner exerts downward force on the forearm with patient resistance||Supraspinatus tendon impingement|
Table 1. Mechanism of the Hawkins-Kennedy and Jobe Tests
Body measurements that correlate with scapular lateralization, dorsal capsule laxity, inferior capsule laxity, dorsal muscle stretch, scapular antetilting and pectoralis muscle length were taken. Each player spiked the ball three times during a research session, and the maximum speed was recorded using a Supido Multi Sports Persion Speed Radar placed at the 9-m line.
The results of the demographic survey are seen in Table 2.
|Weekly practice (h)||12.6||3.4|
|Weekly weight training (h)||2.8||2.2|
Table 2. Participant Demographics
When compared to the NDOM shoulder, scapular lateralization and dorsal capsule laxity were significantly increased in the DOM side. However, the ability to stretch dorsal muscles, scapula antetilting, and pectoralis length were reduced on the DOM side.
Six players reported SPH. Five and 4 players had a positive Hawkins-Kennedy and Jobe test, respectively, but shoulder morphology was similar between participants with SPH and those without. Only 13.6% of the sample had IA, and shoulder morphology of this cohort was similar to the study population. While IA did not effect SS, SPH significantly reduced SS (80.13 km/h vs 94.67 km/hr)
Decreased dorsal capsule laxity was found in players with higher SS. Dorsal capsule laxity was measured as the length between DOM lateral epicondyle and the NDOM acromion while the DOM arm was maximally adducted. NDOM shoulder measurements and SS demonstrated similar results.
Years of experience correlated with increased lateralization of the scapula, and age was associated with increased scapular ante tilting. Compared to setters and liberos, players with spiking roles had a significantly higher spiking speed (86.88 km/h vs. 74.6 km/h), increased height and lower BMI.