著者

森下 義隆 矢内 利政

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.63, no.1, pp.237-250, 2018-06-10 (Released:2018-06-20)

参考文献数

27

被引用文献数

2 1

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The purpose of this study was to examine within-subject differences in bat-swing trajectory between intentional hitting towards the same field and towards the opposite field. 19 industrial league baseball batters and 16 collegiate baseball batters performed same-field hitting (SH) and opposite-field hitting (OH). The movement of the bat during the swing was recorded with two high-speed cameras (1000 fps) for 3D analysis. At the instant of ball impact, the striking surface of the bat faced towards the same field in SH and towards the opposite field in OH. The bat-head trajectory immediately before impact was directed obliquely upward in SH, whereas it was directed obliquely downward in OH. Throughout the swing, the projection angle of the bat on the vertical plane was greater in OH than in SH, and the ratio of the translational component of the bat-head speed to the resultant bat-head speed was significantly greater in OH than in SH. These results suggest that the characteristics of the bat swing in OH provide a suitable impact condition to drive the ball towards the opposite field, as evidence has demonstrated that (1) a batted ball is likely to travel towards the opposite field when the lower half of the ball is hit by a vertically inclined bat, and (2) the striking surface of the bat is unlikely to turn to face towards the same field when the contribution to the resultant bat-head speed is generated more by the translational component of the bathead speed than by the rotational component.

著者

森下 義隆 矢内 利政

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

pp.17004, (Released:2018-02-15)

参考文献数

27

被引用文献数

2 1

---

The purpose of this study was to examine within-subject differences in bat-swing trajectory between intentional hitting towards the same field and towards the opposite field. 19 industrial league baseball batters and 16 collegiate baseball batters performed same-field hitting (SH) and opposite-field hitting (OH). The movement of the bat during the swing was recorded with two high-speed cameras (1000 fps) for 3D analysis. At the instant of ball impact, the striking surface of the bat faced towards the same field in SH and towards the opposite field in OH. The bat-head trajectory immediately before impact was directed obliquely upward in SH, whereas it was directed obliquely downward in OH. Throughout the swing, the projection angle of the bat on the vertical plane was greater in OH than in SH, and the ratio of the translational component of the bat-head speed to the resultant bat-head speed was significantly greater in OH than in SH. These results suggest that the characteristics of the bat swing in OH provide a suitable impact condition to drive the ball towards the opposite field, as evidence has demonstrated that (1) a batted ball is likely to travel towards the opposite field when the lower half of the ball is hit by a vertically inclined bat, and (2) the striking surface of the bat is unlikely to turn to face towards the same field when the contribution to the resultant bat-head speed is generated more by the translational component of the bathead speed than by the rotational component.

著者

志村 芽衣 宮澤 隆 矢内 利政

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

pp.17049, (Released:2017-12-20)

参考文献数

9

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The purpose of this study was to determine the impact conditions that enable a batter to hit a pitched ball toward the opposite field. Three-dimensional finite element analysis was used to construct a model for the impact between a baseball and a wooden baseball bat, and a series of simulations were conducted with various bat angles and under-cut distances. The bat angle at ball impact was set in a horizontal range from -31 to 20° and a vertical range from 0 to 51° with a 3° interval. The under-cut distance was altered by changing the vertical angle of the line of impact in a range from 0 to 30° with a 5° interval. The velocity and angle of projection of the batted ball were determined for each simulated condition. The simulation model was validated by comparing the simulation outcome with the corresponding experimental data obtained from opposite-field hitting practice performed by collegiate baseball players. The results showed that when a batter intends to hit a ball toward a given horizontal angle in the opposite field with the highest speed, the batter should impact the ball with the bat facing about 60% of the horizontal angle toward which to launch the ball and with the line of impact angled upward at 5~10° from the horizontal plane. In addition, the horizontal angle of the batted ball and the velocity of the batted ball were found to change systematically when the vertical angle of the line of impact and the vertical bat angle were altered: For a given horizontal angle toward which to launch the batted ball, there was a trade-off relationship between the vertical angle of the line of impact and the vertical bat angle.

著者

城所 収二 矢内 利政

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.62, no.2, pp.475-490, 2017 (Released:2017-12-19)

参考文献数

16

被引用文献数

1

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The horizontal direction in which a batted ball travels is determined primarily by 2 factors: the horizontal angle of the bat at ball impact (first mechanism) and the interaction between the vertical inclination angle of the bat and the position of the ball impact along the short axis of the bat (second mechanism). As the bat is generally inclined vertically at the moment of ball impact (the head is positioned lower than the grip end), the second mechanism must cause an opposite influence on the horizontal trajectory of the batted ball when a grounder and a fly-ball are compared. The purposes of this study were two-fold: (a) to compare the contributions of the 2 mechanisms to the horizontal direction of batted balls between grounders and fly-balls and (b) to determine the relationship between the contribution of each mechanism and the speed of the batted ball. Sixteen collegiate baseball players were asked to hit balls delivered by a pitching machine aiming towards the same field and the opposite field for 4 trials each. The motions of the ball and the bat around the moment of ball impact were recorded using 2 high-speed cameras (1000 fps). The contributions of the 2 mechanisms to the horizontal directions of the batted balls were calculated from the following variables: the trajectory of the pitched and batted ball, projection angles of the bat in the horizontal plane (horizontal bat angle) and the vertical plane (vertical bat angle), and the angle of the line of impact from the horizontal at ball impact (line of impact angle). The first mechanism contributed 40% or more on average to both the same- and opposite-field hitting of grounders and fly-balls projected towards the fair territory. For fly-balls to the same field and grounders to the opposite field, the contribution of the first mechanism was particularly high (same/fly ball: 118.6±35.2%, opposite/grounder: 109.5±17.8%), and the impact surface of the bat faced toward the batted ball direction. The contribution of the second mechanism was greater for grounders to the same field and fly-balls to the opposite field than the others (same/grounder: 46.7±23.3%, opposite/fly ball: 50.6±49.2%). The speed of the batted ball was negatively correlated with the contribution of the second mechanism (r=−0.73, p<0.01). Therefore, in order to hit a ball with higher speed, a batter should adjust the timing of impact to use the first mechanism, and should strike near the center of the ball.

著者

東 洋功 矢内 利政

出版者

日本バイオメカニクス学会

雑誌

バイオメカニクス研究 (ISSN:13431706)

巻号頁・発行日

vol.16, no.3, pp.128-137, 2012-12-10 (Released:2022-04-06)

参考文献数

11

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The purpose of this study was to describe the angular momentum of the runner's body about the center of mass (CM) during the maximum-effort sprinting along a curved runway. Ten male collegiate sprinters were asked to sprint along the 2nd lane on an official 400m track. The performances were recorded with four high speed cameras. The DLT algorithm was used for 3D reconstruction and the angular momentum of the whole body about the CM was calculated. The results showed that the runner’s body possessed throughout the stride cycle an inward-directed component (33.5×10–3±2.8×10–3s–1) of angular momentum and that the head and torso possessed a cranially-directed component (0.4×10–3±0.2×10–3s–1). The antero-posterior component of angular momentum changed its sense from forward- to backward-direction during the right ground contact phase. These results indicate (a) that the runner's head and torso changed its orientation continuously throughout the support- and the airborne-phases to face forward along the curved runway and (b) that the angular impulse exerted on the body during the right ground contact phase changed the direction of the forward somersaulting angular momentum of the whole body possessed primarily by the limbs, so that the runners could maintain the plane of the limbs' rotary motion in the tangential direction to the curved runway.

著者

永見 智行 木村 康宏 彼末 一之 矢内 利政

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.16021, (Released:2016-08-29)

参考文献数

25

被引用文献数

4 5

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In this study, we analyzed the kinematic characteristics of various types of baseball pitches by elite baseball pitchers, and tested a null hypothesis that “no type of pitch has the same kinematic characteristics as another.”  A high-speed video camera was used to record the initial trajectory of the pitched ball thrown by 84 skilled baseball pitchers. Each pitcher was asked to throw all the different types of pitch he would use in competition and practice, and to self-declare the type of pitch used for each throw. The kinematic characteristics of each pitched ball were analyzed as ball speed, the direction of the spin axis, and the spin rate. A custom-made device was used to analyze the direction of the spin axis and the spin rate, and the ball speed was measured with a radar gun. One-way ANOVA with the Games-Howell post hoc test was used to test the hypothesis.  The total of 364 pitches were categorized into 11 self-declared pitch types. Four of 10 pitch types thrown by more than one pitcher - the four-seam fastball, slider, curveball and cutter - had unique kinematic characteristic distinct from all of the other pitch types. No significant differences were found in any of the kinematic parameters between 1) changeup and sinker, 2) forkball and split-fingered fastball, and 3) two-seam fastball and shoot ball. Therefore, the hypothesis was retained for these three pairs of pitch types: although they were kinematically similar, the pitchers categorized them as different types.  When the breaking ball was compared with the four-seam fastball, they were classifiable into three types: 1) pitches with a slower ball speed and lower spin rate with a different direction of spin axis (changeup, sinker, forkball and split-fingered fastball), 2) pitches with a slower ball speed, different direction of the spin axis and a spin rate comparable to the four-seam fastball (slider, curveball and cutter), and 3) pitches with a comparable ball speed, similar spin axis direction, and lower spin rate (two-seam fastball and shoot ball). These data revealed that the kinematic characteristics of some pitch types are quite different from those described in baseball coaching handbooks.

著者

丸山 祐丞 近田 彰治 矢内 利政

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.57, no.2, pp.641-651, 2012 (Released:2012-12-05)

参考文献数

14

被引用文献数

4 3

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The purpose of this study was to test the hypothesis that the position of the center of buoyancy (CB) relative to the center of mass (CM) lay more caudally when the abdominal breathing technique is used, as compared with the chest breathing technique. Ten healthy men who practiced the abdominal and chest breathing techniques participated. The position of the CB, CM, and the distance between them (CB-CM distance) were determined as time-series data during inhalation with each breathing technique, and the changes in the positions and distance due to inhalation were compared between the two techniques. The results showed that both the CB and CM translated due to the inhalation and that the amount and direction of the translations differed between the two techniques (p<0.01). The increase in the CB-CM distance was significantly smaller (p<0.01) with abdominal breathing (1.11 cm) than with chest breathing (1.21 cm). For both breathing techniques, the CB was located more cranially to the CM, regardless of the amount of inhalation. These data demonstrate clearly that the position of the CB relative to the CM lies more caudally with the abdominal breathing technique than with chest breathing, thus supporting our hypothesis. These results indicate that breathing technique influences the magnitude of the moment of buoyant force around the CM and the swimmer's ability to float horizontally on the water surface.

著者

志村 芽衣 宮澤 隆 矢内 利政

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.64, no.2, pp.487-500, 2019-12-16 (Released:2019-12-20)

参考文献数

16

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The purpose of this study was two-fold; to determine the optimum impact condition for maximizing flight distance toward the opposite field and to examine the influence of the bat angles at impact on the batted ball characteristics (speed, rotation, and angle immediately after impact) and the flight characteristics (distance, trajectory, and time). Various impact conditions were defined using 3 factors: the angles of the bat at impact projected to the horizontal and vertical planes, and the vertical inclination angle of the line of impact (the product of the sine of this angle and the radius of the ball determines the under-cut distance). Three-dimensional finite element analysis was used to construct a model of impact between a baseball and a wooden baseball bat and to conduct simulation analysis. The initial flight condition of the batted ball after the impact was determined for each simulated condition, and the flight distance was estimated from the initial flight condition. The results showed that a nearmaximum flight distance of 90-95 m was attained over a wide range of the opposite field when the bat head was not lowered substantially more than the grip-end. However, when the bat head was lowered substantially more than the grip-end, the flight distance attainable with the given impact condition decreased as the vertical bat angle increased, and the range of horizontal bat angle within which a great flight distance was attainable became narrower. The latter results suggest that a batsman needs to acquire a sophisticated technique with a greater precision of ball impact to hit a ball toward a given horizontal angle in the opposite field if the bat swing is characterized as lowering of the bat head to a large extent.

著者

谷中 拓哉 近田 彰治 矢内 利政

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

pp.16056, (Released:2017-01-24)

参考文献数

12

被引用文献数

1

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A wide range of topspin rotation of a bat around the long-axis, referred to as “rolling”, has been observed in baseball batting, but the mechanical reasons for the large variability among individual batters has not been examined. The purpose of this study was to investigate the factors determining this variability in rolling velocity among professional baseball players. Twenty-nine professional batters each performed eight “free-batting” trials. An electromagnetic tracking device was used to measure the three-dimensional rotational motion of the bat in each trial. The rolling velocity was 678±376°/s, comprised a negative contribution attributable to the batter's effort of exerting torque (Mechanism 1; −1144±488°/s) and a positive contribution attributable to the gyroscopic effect (Mechanism 2; 1808±339°/s). A significant positive correlation (r=0.67, p<0.05) was found between the rolling velocity and the negative contribution of Mechanism 1. These results indicate that (a) the torque exerted by the batter resists the rolling and that (b) a higher rolling velocity is attained by batters who exert a smaller resistive torque on the bat than those who exert a larger torque. On the other hand, no correlation (r=0.09) was found between the rolling velocity and positive contribution of mechanism 2. These findings suggest that the batter makes an active effort to resist rolling, and that the amount of resistive torque exerted by the batter is the primary reason for the inter-individual difference in rolling velocity attained at the instant of ball impact. As the resistive torque is likely to be exerted by the nobside hand in the form of pronation torque (Ae et al. 2015) and the pronation causes lowering of the bat-head (increasing nutation angle), a reduction of the pronation torque should decrease the resistive torque acting on the bat, helping to attain a high rolling velocity. In fact, we observed a greater deceleration of nutation velocity in the fast-rolling group than in the slowrolling group (p<0.05). To attain the high rolling velocity, therefore, we suggest that batters should aim to build up the nutation velocity of the bat until about 50 ms before ball impact, and then vigorously decelerate it immediately before ball impact.

著者

矢内 利政

出版者

日本バイオメカニクス学会

雑誌

バイオメカニクス研究 (ISSN:13431706)

巻号頁・発行日

vol.11, no.3, pp.200-212, 2007

著者

城所 収二 若原 卓 矢内 利政

出版者

日本バイオメカニクス学会

雑誌

バイオメカニクス研究 : 日本バイオメカニクス学会機関誌 (ISSN:13431706)

巻号頁・発行日

vol.15, no.3, pp.78-86, 2011

著者

城所 収二 若原 卓 矢内 利政

出版者

日本バイオメカニクス学会

雑誌

バイオメカニクス研究 : 日本バイオメカニクス学会機関誌 (ISSN:13431706)

巻号頁・発行日

vol.16, no.4, pp.220-230, 2012

著者

設楽 佳世 緑川 泰史 太田 めぐみ 矢内 利政 金久 博昭 福永 哲夫 川上 泰雄

出版者

一般社団法人日本体力医学会

雑誌

体力科学 (ISSN:0039906X)

巻号頁・発行日

vol.60, no.4, pp.453-462, 2011 (Released:2011-08-30)

参考文献数

31

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In this study, we examined applicability of existing equations to predicting the body surface area (BSA) of children, and newly developed prediction equations for the BSA of children. BSA of 87 children of both genders (7∼12 yr) was determined by the three-dimensional photonic image scanning (3DPS), which was used as reference. BSA predicted using existing equations yielded overestimation or underestimation and/or a systematic error with respect to the reference. BSA prediction equations for boys and girls were developed using height and body mass as independent variables for the validation group and cross-validated for another group. The standard errors of estimation of the prediction equations were 105 cm2 (0.9 %) for boys and 158 cm2(1.4 %) for girls. In the cross-validation group, there was no significant difference between the predicted and measured values without systematic errors. These findings indicate that existing equations cannot accurately predict BSA of children, and that the newly developed prediction equations are capable of predicting BSA of children with adequate accuracy.

著者

谷中 拓哉 矢内 利政

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.63, no.2, pp.799-810, 2018-12-10 (Released:2018-12-20)

参考文献数

18

被引用文献数

1

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In baseball batting, rotation around the long axis of the bat, know as " rolling ", has been observed. A batter who can attain a higher rolling speed before ball impact can achieve a higher rotation speed of the struck ball, which increases the ball’s flight distance. It has been suggested that batters who swing the bat with high nutation can attain a high rolling speed. The purpose of this study was to investigate the effect of instruction aimed at increasing the rolling speed in baseball batting. Ten batters performed tee-stand batting under 2 conditions: a usual swing (CON1), and a swing after being instructed to position the bat vertically, and then swing by rapidly lowering the bat head (CON2). The three-dimensional motion of the bat was measured using a small accelerometer and gyro sensor attached to the grip-end of the bat. This sensor was able to measure the swing speed, swing time, rolling speed, swing angle (angle between the bat head velocity vector and the horizontal plane) and vertical angle of the bat (angle between the long axis of the bat and the horizontal plane) before ball impact and the swing trajectory from the start of the swing until ball impact. The rolling speeds employed were 726°/s (CON1) and 854°/s (CON2). The rolling speed for CON2 was significantly higher than that for CON1 (p <0.05). On the other hand, there was no evident difference in swing speed between CON1 (30.1 m/s) and CON2 (30.2 m/s), nor were there any differences in other swing parameters before ball impact. Batters who swung the bat at a high nutation speed in response to instruction increased the rolling speed, but those who were unable to change the swing trajectory and nutation speed failed to change the rolling speed. These results indicate that batters increase the rolling speed without changing swing parameters such as swing speed, swing time and the vertical angle of the bat in response to the above instruction.

著者

矢内 利政 城所 収二 宮澤 隆 志村 芽衣

出版者

早稲田大学

雑誌

基盤研究(B)

巻号頁・発行日

2014-04-01

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通常のバッティングではバットの芯付近でボールの中心を打撃することにより高い打球速度が獲得でき、バントにおいてはバットの芯とそのやや先でボールの中心を打撃することにより打球速度は低くなるという現象を力学的に説明することを目的とした。その結果、①ヘッド速度が一定の条件でも、スイング速度と並進速度の組み合わせにより打球速度、及び打球速度を最大化するインパクト位置は変化することが明らかになった。これらの現象は, スイング角速度、重心速度、インパクト位置の条件の変化に伴いバットの反発係数が変動することに加え、ボールとバットが有する運動量が互いの間で転移する方向と大きさの変化により生じることが示された。