2019 年 8 巻 4 号 p. 159-164
The impact of characteristic physical functions on location of arm pain in youth baseball players is unclear. This study aimed to identify the differences in characteristic physical functions between youth baseball players with and without throwing-related arm pain and to clarify these differences according to location of shoulder and elbow pain during pitching. One-hundred nine junior high school baseball players (aged 12-15 years) who participated in a medical checkup underwent clinical assessment, ultrasonography, and physical function measurements. Bilateral passive range of motion (ROM) of the shoulder and elbow were measured. Shoulder muscle tests measured the strength of the throwing arm. Before the examinations, participants completed a questionnaire about their age, gender, years of play, and position in baseball. Participants were divided into 4 groups according to arm pain: non-injured group (no pain), shoulder pain group, medial elbow pain group, and osteochondritis dissecans (OCD) of the humeral capitellum group. Group differences in physical function and baseball exposure variables were analyzed through parametric and nonparametric tests. Twenty-six players sustained throwing-related pain in the shoulder or elbow. Elbow extension and flexion deficits were significantly greater with elbow injury. Our study suggests that dominant elbow extension and flexion ROM may increase the risk of throwing-related elbow pain in junior high school baseball players. We could not clarify the characteristics of shoulder pain in this study; thus, further research is required to improve understanding of these characteristics and their implications.