| Keywords |
Humeral head retroversion ; Scapula nuetral ; Scapula protracted |
| Abstract |
Shoulder injuries are influenced by collapse of the balance between the thoracic vertebra and the shoulder girdle alignment to the kinematics and the shoulder joint muscular strength. The purpose of study was to investigate the relationships among shoulder postures and humeral head retroversion (HHR), and to measure the effect of scapula neutral (SN) and scapula protracted (SP) on shoulder internal (IR) and external rotation (ER) muscle strength. Subjects in this investigation were 10 men with no history of shoulder injury or disorders. They all participated in overhead sports at least three days a week, and volunteered to participate in this study. They performed IR and ER concentric contraction in 2 scapular positions (SN and SP). They measured forward shoulder head posture (FSP), pectoralis minor length (PML), range of motion (ROM), HHR on dominant and non-dominant. There is a pattern of increased ER and decreased IR in the dominant shoulder that significantly correlates with an increase in HHR. The HHR demonstrated the negative correlation with FSH and ROM for IR, and positive correlation with PML. Isokinetic muscle strength was smaller for SP compared with SN. These postural changes are thought to occur concurrently with an imbalance of the musculature, and rehabilitation program commonly involves addressing both posture and muscle imbalance. The potential adverse effects of scapular protraction on shoulder rotation strength should be considered during the evaluation and treatment of shoulder pain for overhead throwers. |