Sekiguchi T, Hagiwara Y, Yabe Y, et al. - Baseball players (aged 9-12 years) who participated in the National Junior Sports Clubs Baseball Festival were assessed to investigate the relationship of joint flexibility of the trunk and lower extremities and dynamic postural control with the elbow and shoulder pain among elite young baseball players. A total of177 of 210 players surveyed without elbow or shoulder pain were incorporated in the analysis. Of the individuals, 16 reported having elbow or shoulder pain during the tournament. In comparison with those without pain, participants with the incidence of elbow or shoulder pain had a notable limitation in hip internal rotation (IR) of the stride leg. No notable relationships of other joint flexibilities and the Star Excursion Balance Test with elbow or shoulder pain were discovered. Therefore, a reduced hip IR range of motion of the stride leg had a significant correlation with the elbow or shoulder pain incidence. Moreover, for the opposition of elbow and shoulder pain, players, coaches, and clinicians should acknowledge the physical function of the trunk and lower extremities.