Comparative analysis on the physique and batting records of the players in the National Summer High School Baseball Tournaments before and after the adoption of metal bats.

To clarify the influence of the introduction of metal bats on the physique and batting records of the players in the National Summer High School Baseball Tournaments, a comparative analysis was conducted between height, body weight, body-weight ratio (body weight/height), batting average and home run average of the best four teams' players (n = 493) and those of the other teams' players (n = 4,590) in three periods: the period of the use of wooden bats, that of the use of both wooden and metal bats and that of the use of metal bats. In the period of metal bat use, the mean values of physique of the best four teams' players were significantly larger (P < 0.05) and their average number of home runs was significantly higher than those of the other teams' players (P < 0.01). The only significant differences between the two groups in those indices for each time period were for height in the wood and metal/wood periods. This study demonstrated that the differences between the home run average and physique, including height, body weight and body-weight ratio of the best four teams and the rest of the teams were the greatest after the use of metal bats. These findings suggest that the importance of the home run average increased and was associated with large-size of physique after the use of metal bats in the National Summer High School Baseball Tournaments.