バイオメカニクス研究
Online ISSN : 2434-4621
Print ISSN : 1343-1706
19 巻, 4 号
選択された号の論文の2件中1~2を表示しています
原著論文
  • 佐久間 亨, 阿江 通良, 小林 育斗
    原稿種別: 原著論文
    2015 年 19 巻 4 号 p. 192-200
    発行日: 2016/03/15
    公開日: 2022/04/06
    ジャーナル フリー

    The purpose of this study was to investigate effects of the trunk lean during gait on the use of mechanical energy in elderly people. Ten health elderly people were asked to walk in the conditions of normal for the subjects and in trunk-leaned position, that is lumbar flexion position with a brace. The gait motion was captured with VICON MX T-series and the ground reaction forces during support phase were collected with two Kistler force platforms. With the increase in the trunk forward lean, the positive work at the hip increased. However, the negative work at the knee decreased in the range of 0 to 15 degrees trunk lean but increased beyond 15 degrees. The result indicated that the effectiveness of mechanical energy use in gait for the elderly people decreased with the trunk forward lean more than 15 degrees due to the increase in the mechanical work done by the leg joints.

  • 森下 義隆, 平野 裕一, 矢内 利政
    原稿種別: 原著論文
    2015 年 19 巻 4 号 p. 201-215
    発行日: 2016/03/15
    公開日: 2022/04/06
    ジャーナル フリー

    The purpose of this investigation was to describe how the bat-head speed and the orientation of the bat at ball impact were generated in baseball hitting. Seventeen male collegiate baseball players performed tee-batting aiming at hitting the ball toward the center field. A motion capture system (500Hz) was used to record three-dimensional coordinate of the bat during the performance. The resultant force and the resultant moment exerted on the bat by the batter’s hands were determined with the inverse dynamics approach and their contributions to the bat-head speed and the orientation of the bat were computed with the forward dynamics approach. The resultant force exerted on the bat along the long axis produced approximately 70% of the bat-head speed at ball impact, and the couple moment and the moment of resultant force produced 25% and 7%, respectively. The bat-head speed due to the gravity and the gyroscopic effect was negligible small. For the orientation of the bat at ball impact, the horizontal angle was produced by the positive contributions of the couple moment that exceeds the negative contributions of the moment of resultant force. The vertical angle was produced by the positive contributions of the moment of resultant force that exceeds the negative contributions of the couple moment and the gyroscopic effect.

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