From 2006 to 2008, we longitudinally examined the physical conditions of high school baseball players. The purpose of this study was to investigate the relationship between disorders and physical conditions. We evaluated 34 high school baseball players. The following factors were evaluated: (1) latissimus dorsi test, (2) heel buttock distance (HBD), plasticity of lower limbs, (3) squat 1 & 2, (4) MMT of the lower trapezius, (5) EET, (6) EPT, (7) MMT of the hip adductor, (8) step up, and (9) step down. We also recorded the number of players with shoulder and elbow disorders. Core function, lower trapezius, step up, and step down improved well, however, results of squat 1 & 2 did not change. The number of players with shoulder disorders diminished from 8 to 5, and those with elbow disorder from 5 to 0. The players with shoulder disorders especially showed weakness of hip adduction on the pivoting side and a poor result of EET on the throwing side. Six players, healing shoulder disorder, improved their result of squat 2 and function of standing on the pivoting side foot, whereas the remaining players without healing , indicated a poor result of squat 2. The muscle strength of the lower trapezius, core stability, and function of standing on one foot improved with training, however training provided no effect on plasticity of the lower limbs. This study showed that the throwing shoulder and elbow injury related to the plasticity of the lower limb, core function, and standing on the pivoting foot.
