5 0 0 0 OA 一流女子ソフトボール投手が投じているボールの回転と飛翔軌道の特徴
- 著者
- 森下 義隆 村田 宗紀
- 出版者
- 独立行政法人 日本スポーツ振興センター国立スポーツ科学センター
- 雑誌
- Journal of High Performance Sport (ISSN:24347299)
- 巻号頁・発行日
- vol.6, pp.88-100, 2020 (Released:2020-10-10)
- 参考文献数
- 20
- 被引用文献数
- 1
In this study, we investigated the kinematic characteristics of various pitch types thrown by skilled softball pitchers. Nine female softball pitchers from the national Japanese softball team were requested to throw various pitch types that are used in competition and practice using the windmill style, while a three-dimensional motion capture system consisting of 20 infrared cameras (500 Hz) recorded reflective markers attached to the ball. The kinematic characteristics, such as the ball speed, spin rate, and direction of spin axis (angular velocity vector) were calculated from the measured coordinate values. The types of pitches (fastball, riseball, drop, and changeup) thrown by more than 5 pitchers were analyzed. The spin axes of all the analyzed trials were mostly oriented in the direction of the ball and upwards. The average ball speed of the fastball pitched by all pitchers had the highest, and in the case of the right-handed pitcher, the displacement of flight trajectory on the home plate changed by approximately 0.17 m downward and 0.06 m toward the left-handed batter under the influence of the lift force, as compared to that of the balls that were projected without rotation. Furthermore, when the flight trajectories of other pitch types were compared with that of fastball, the riseball, drop, and changeup types were shown to change in the upward, downward, and upper left directions, respectively. Our findings can be used as a guide to develop new pitch types or improve those that are currently employed in the game.
2 0 0 0 OA 上肢および上胴に着目したテニスサーブにおける回転の打ち分け
- 著者
- 村田 宗紀 藤井 範久
- 出版者
- 一般社団法人 日本体育学会
- 雑誌
- 体育学研究 (ISSN:04846710)
- 巻号頁・発行日
- vol.59, no.2, pp.413-430, 2014 (Released:2014-12-20)
- 参考文献数
- 21
- 被引用文献数
- 9 4
The purpose of this study was to investigate the relationship between motion and ball spin in tennis serves. Ten male university tennis players participated. The three-dimensional coordinates of the players performing flat, kick and slice serves were collected using a motion capture system with 8 cameras (250 Hz). Similarly, the three-dimensional coordinates of reflective markers on the ball were also collected (500 Hz). The primary variables computed were: racquet face velocity and direction at impact, velocity and angular velocity of the ball after impact, hitting point, angles of the upper limb joints, and segment angles of the upper trunk. The differences in racquet face velocity among flat, kick, and slice serves were divided into the following terms: 1) ΔVposture: A difference in velocity resulting from a change in upper trunk posture, 2) ΔVswing: A difference in velocity resulting from a change in arm swing (kinematics of the upper limb), 3) ΔVutrk: A difference in velocity resulting from a change in upper trunk translational and rotational motion. Repeated measures ANOVA (p<0.05) with Bonferroni multiple comparison was used to evaluate the effects of changes in form (with differences in ball spin) on each parameter. The findings are summarized as follows.1) The impact point and swing direction were mainly controlled not by a change in arm swing motion, but by a change in upper body posture.2) To generate ball spin, it is necessary to avoid a head-on collision between the ball and the racquet (a normal vector of the racquet face is parallel to the racquet face velocity vector). Therefore, players decreased the amount of upper trunk leftward rotation in kick and slice serves at the point of impact so as to swing the racquet more laterally.3) It is necessary to swing the racquet more vertically in order to lean the rotation axis of the ball. Therefore, players controlled the upper trunk leftward-rightward and forward-backward leaning in a kick serve at the point of impact.4) Changes in upper body posture cause changes in the direction the racquet faces. Therefore, players mainly controlled their elbow pronation-supination angle in order to maintain a racquet face direction that satisfies a legal serve.
1 0 0 0 OA 硬式テニスサーブにおけるエネルギー形態に着目したラケット保持腕の力学的エネルギーフロー
- 著者
- 村田 宗紀 藤井 範久 鈴木 雄太
- 出版者
- 一般社団法人 日本体育学会
- 雑誌
- 体育学研究 (ISSN:04846710)
- 巻号頁・発行日
- vol.60, no.1, pp.177-195, 2015 (Released:2015-06-13)
- 参考文献数
- 23
- 被引用文献数
- 4 1
Mechanical energy is known to be transferred between a body segment and a joint. However, the transformation of this energy has not been classified. By focusing on the racquet-holding arm during a tennis serve, the present study examined the transformation between translational and rotational energies due to the joint force, and investigated the kinetic chain from the viewpoint of energetics. Twenty-two tennis players were asked to perform flat services to the deuce side (i.e., the receiver's right side), and the three-dimensional coordinates of reflective markers attached to each player and racquet were collected with a motion capture system. The mechanical power acting on each segment and the mechanical energy generated/absorbed by each joint were divided into the following components: (1) STP=the time rate of change in the rotational energy of a segment due to the joint torque, (2) JTP=the generation/absorption of rotational energy due to the joint torque, (3) JFPt=the time rate of change in the translational energy of a segment due to the joint force, and (4) JFPr=the time rate of change in the rotational energy of a segment due to the moment of the joint force. The findings are summarized below. 1. The proposed method can divide the power acting on the segment due to joint force into the translational component (JFPt) and the rotational component (JFPr). 2. The racquet-holding arm mainly acquires mechanical energy as translational energy with decreasing rotational energy of the upper trunk (around right-leftward rotation). 3. The main role of the shoulder joint is not to generate rotational energy but to change the energy form (from translational energy to rotational energy). 4. The main role of the phase before most of the shoulder external rotation is to store the translational energy in the racquet-holding arm. 5. The main role of the phase after most of the shoulder external rotation is to transfer the translational and rotational energies to the racquet. 6. The proposed method can quantify not only the generation/absorption and transmission of mechanical energy but also the transformation of the energy form. Therefore, this method may produce new findings that have not yet been clarified.
1 0 0 0 OA 下肢および胴部に着目した硬式テニスサーブにおけるボールの回転の打ち分け
- 著者
- 村田 宗紀 藤井 範久
- 出版者
- バイオメカニズム学会
- 雑誌
- バイオメカニズム (ISSN:13487116)
- 巻号頁・発行日
- vol.22, pp.155-166, 2014 (Released:2017-02-15)
- 参考文献数
- 18
- 被引用文献数
- 1 2
硬式テニスにおいて, サーバーは様々な回転や速度のサーブを打球することで相手に球種を予測されにくくする. これまでに球種の打ち分け技術に関するkinematics的分析から, 球種間のスウィング方向の差は上肢によるスウィング操作ではなく, 主にインパクト時の上胴の姿勢の差に起因することが報告されている. そこで, 本研究では上胴の姿勢を決定する主要因であろう下胴と下肢のkineticsについて検討することを目的とした. その結果, 右利き選手の場合, 左脚は主にヘッドスピード獲得のための力学的エネルギーを発生し, 右脚は力学的エネルギーを発生するだけでなく, 回転を打ち分けるために胴部の姿勢を調整する役割も担っていることが明らかとなった.