[Purpose] The purpose of this study was to clarify the features of rotation range of motion (ROM) of the shoulder joints of young athletes. [Subjects and methods] The Subjects included 25 little league baseball players and 17 little kendoplayerswho were healthy children belonging to the little league baseball club and little kendo club of H grade school. After examination with a questionnaire, external and internal rotation ROM at 90°abduction of the shoulder joint were measured and compared between the little league baseball and little kendo players. Comparisons were made on the dominant hand and non-dominant hand sides. [Results] None of ROM measurements showed significant differences between the little league baseball and little kendo players. Moreover, as for external rotation ROM, no significant difference was found between the dominant hand and non-dominant hand sides in both groups. However, as for internal rotation ROM, the dominant hand side showed lower values than the non-dominant hand side. [Conclusion] The results of this study suggest that in a school period, shoulder-joint internal rotation ROM is reduced on the dominant hand side.
