Background: The purpose of this study was to determine a characteristic of scapula function and factors related to throwing disorder in professional baseball pitchers.
Methods: This study included 35 professional baseball players (21 pitchers and 14 fielders) who underwent a new medical checkup system in spring camp of March 2010. Shoulder and scapula function consists of 12 factors: (1) scapula-spine distance, (2) scapular retraction test, (3) scapular stability test, (4) muscle strength of the lower trapezius, (5) active compression test, (6) impingement signs, (7) Internal rotation from 3rd to 2nd position, (8) full can test and empty can test, (9) combined abduction test, (10) horizontal flexion test, (11) hyper external rotation test, and (12) elbow push test. Trunk, hip, and foot function consists of 6 factors: (1) modified trunk rotation test, (2) hand knee opposite test, (3) straight leg raising test, (4) range of motion of internal rotation of the hip, (5) heel-buttock distance, and (6) looping gait. These parameters were compared between the pitchers and the fielders.
Results: The following parameters showed significant differences: 1) scapular retraction test was positive in 57% of the pitchers versus 21% of the fielders; 2) scapular stability test was positive in 61% (pitchers) versus 14% (fielders); and 3) muscle weakness of the inferior trapezius was observed in 81% (pitchers) versus 35% (fielders). Shoulder and/or elbow disorders occurred in 12 pitchers (57%) during the following season.
Conclusion: Among professional baseball pitchers, limitation of scapula retraction and muscle weakness of the lower trapezius are more likely to lead throwing disorders.
