The Effects of Short-term Scapular Control Training in Overhead Athletes With Shoulder Impingement Syndrome

Subacromial impingement syndrome (SIS) is a common disorder of shoulder joint. SIS has been accounted for 44-65 % of all shoulder pain. It is believed that one important contributing factor is scapular dyskinesis. Patients with SIS demonstrates scapular dyskinesis, including decrease in upward rotation, scapular posterior tilt, and external rotation. Altered muscle activity of scapular muscles may contribute to scapular dyskinesis, such as increase in activity of upper trapezius, and decrease in activity of lower trapezius and serratus anterior. In addition to these changes in neuromuscular control, central nervous system may be re-organized in patients with musculoskeletal disorders. Evidence has been reported that center of gravity of motor mapping changes, corticospinal excitability decreases and inhibition increases in patients with shoulder injuries such as instability, rotator cuff tendinopathy and SIS. These corticospinal changes are believed to be related to chronicity of symptoms and lack of treatment effects. Previous studies have applied many types of treatments to SIS, such as manipulation, taping, and exercises. However, most studies mainly focused on the outcomes of pain and function, few studies investigated changes in neuromuscular control following treatments. Yet, no study has addressed how corticospinal system changes following treatment in patient with shoulder injuries. Motor skill training, which has been widely used in training healthy subjects or patients with neurological disorders, has been shown to change corticospinal systems, including increasing excitability and decreasing inhibition. To our knowledge, no study has integrated the concepts of motor skill learning into a short-term treatment or investigated the effects of motor skill training on corticospinal systems in patients with SIS. The purposes of the study are to investigate the effects of short-term motor skill training on pain, neuromuscular control, corticospinal system in pat