The purpose of this study was to investigate kinematic changes in the baseball batting motion for high, middle and low hitting points. Subjects were ten right-handed male skilled batters of a varsity baseball club. Nine hitting points were set according to the baseball rules : three heights (high, middle, low) times three courses (inside, center, outside) based on the subject's height and the width of a home plate. The subjects were requested to hit a ball on a batting tee randomly assigned one of nine hitting points at each trial. Angular kinematic data were collected at l20Hz with a Vicon 612 system.

In case of the high hitting point, the right shoulder flexion and left shoulder horizontal-adduction at the instant of Left upper arm perpendicular to the hitting direction (LUP), and the left shoulder flexion at the Impact (IMP) were smaller than those of the middle height. In case of the low hitting point, the right hip flexion at the Toe-on, and the right shoulder flexion, extension of both elbows, and flexion of both hips at the LUP were greater than those of the middle height. The left elbow extension, left shoulder flexion, adduction and flexion of both hips were greater at the IMP than those of the middle height.

These results indicated that to hit a ball at high and low points appropriately a batter first adjusted flexion-extension and abduction-adduction of the hip joints, and then swing the bat adjusting both arms, especially the left arm just before the impact.

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The purpose of this study was to investigate kinematic changes at the baseball batting motion for inside, center and outside hitting points. Subjects were ten right-handed male skilled batters of a varsity baseball club. Nine hitting points were set according to the baseball rules: three heights (high, middle, low) and three courses (inside, center, outside) based on the subject's height and the width of a home plate. The subjects were requested to hit a ball on a batting tee randomly assigned one of the nine hitting points in each trial. Kinematic data were collected by using a Vicon 612 system with nine cameras operating at 120 Hz. Angular kinematics computed were joint angles of the right and left elbows, shoulders, ankles, knees and hips, and rotation angles of the shoulders and hips at the instant of events of batting.

In case of the outside hitting point, the rotation angle of the shoulders toward the opposite hitting direction at the instant of Toe-on was greater, and the rotation angle of the hips toward the hitting direction at the Swing start (SS) was smaller than those of the center point. The rotation angle of the shoulders and hips toward the hitting direction at the instant of Left upper arm parallel (LUP) to the hitting direction was smaller, and the left elbow extension was greater than those of the center point. The abduction of the left shoulder and the rotation angle of the shoulders and hips toward the hitting direction at the impact were smaller than those of the center point. In case of the inside hitting point, the rotation angle of the shoulders toward the opposite hitting direction at the instant of Toe-on was smaller than those of the center point. The rotation angle of the shoulders toward the hitting direction, and the extension of the left ankle at instant of LUP was greater than those of the center point. The rotation angle of the shoulders and hips toward the hitting direction, and the extension of the left ankle and knee at the impact were greater than those of the center point.

These results indicated that to hit the ball at the inside and outside hitting points effectively a batter should first adjust the rotation of the shoulders and hips prior to the swinging down the bat with the upper limbs toward the hitting points.

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　本稿は、佐藤栄作内閣における保利茂官房長官―木村俊夫官房副長官という体制の成立経緯と、それがいかに機能したのかを明らかにするものである。

　1968年11月30日、佐藤総理は内閣改造を行い、建設大臣の保利を官房長官に、木村官房長官を副長官とする異例の人事をとった。首席秘書官だった楠田實は、この2人による体制を「大型官房」と呼ぶ。

　「大型官房」成立時、政権は沖縄返還や大学紛争といった課題に直面していた。「大型官房」には、保利を長官に起用し、木村を副長官として官邸にとどめることで官邸を強化する意味が存在した。木村は、楠田とともに官房長官期からメディアやブレイン対応を主導していた。「大型官房」は約3年という長期間継続し、佐藤内閣の長期政権化の一因となったと評価できる。

　この体制は、制度改革ではなく、人事の運用により官邸を強化するものであり、自民党長期政権化における官邸強化の方法であった。この仕組みはその後の内閣にも継承された。

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The purpose of this study was to clarify how the adoption of the metal bat made the technique of the team at bat and the tactics they used change in high school baseball after the 1970s. When a baseball tool changes, the technique and tactics change greatly. One such change occurred with the introduction of "the metal bat" in Japanese baseball after World War II. One doesn't think about a change in baseball technique and tactics regarding only the change in the style of play, but one must also think about how this fit in to economical changes as well, and the society as a whole. To date, there has been no historical research conducted on a change in baseball technique and tactics from the point of view of technique alone. Previous studies of Japanese baseball history are the following: A historical study on the baseball from its introduction to the present, discussions of baseball technique, on the baseball stadium, and on the relationships between the tools and the tactics put together. The following facts were confirmed by this study. 1) Increase in the population of baseball players brought about the introduction of the metal bat. 2) A change was seen in the technique of the team at bat and the tactics used by them due to the introduction of the metal bat. 3) The defense adapted to the change in technique and tactics of the team at bat, and adjusted their style of play accordingly.

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