The purpose of this study was to clarify the low back pain with reference to athletic activities during growth stage. Five college baseball players with low back pain and five healthy baseball players were paticipated as subjects. The relationship between the low back pain and the differences between right and left sides of muscular strength of extrimities, degrees of development and electrical activities of back muscles were analiezed by using measures of muscular strength, Moire photo methods and electromyographical recordings. As the results, no significant differences between right and left sides were found in maximal isometric strength of arm flexsors and leg extensors for both groups of baseball players. Differences between right and left sides, however, were estimated in the muscular development of low backs for players with low back pain by analysis of moire photos. Differences of electrical muscular activities between right and left backs while performing back lift were varied in the group with low back pain. Some players showed similar patterns of electromyographical recordings as of healthy players, but others showed different patterns. It was suggested that the differences of electrical muscular activities of backs were more significant in the players with low back pain than in healthy players.

DESCENTE SPORTS SCIENCE Vol.10/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE