The associations of selected technical parameters with discus throwing performance: a cross-sectional study

The aim of this study was to identify associations between discus throwing performance and the technical parameters of: hip-shoulder and shoulder-arm separation, trunk forward-backward tilt, and throwing-arm elevation angles. Video data of male and female discus throwers' competitive performances were captured during major competitions. Real-life three-dimensional coordinates of 21 body landmarks, and the discus's centre, were obtained for 94 trials using the direct linear transformation procedure. Each technical parameter was reduced at six critical instants. The trend of each parameter across four standards of performance was analysed separately for both sexes. For the female throwers, hip-shoulder and shoulder-arm separations after the flight phase, as well as forward-backward trunk tilts at the beginning and end of the throwing procedure were associated with performance. For male throwers, only the hip-shoulder separation immediately before the flight phase was associated with performance. These findings suggest that the relationships between technical parameters and discus throwing performance are different for males and females. Our results suggest that elite female discus throwers are reliant on effective technique throughout the throwing procedure to achieve long distances, whereas male discus throwers may have a relatively homogeneous technique, and a dependence on physical strength to achieve their long throws.     

The relationship between discus throwing performance and combinations of selected technical parameters

The aim of this study was to determine the relationship between discus throwing performance and the following technical parameters: hip–shoulder and shoulder–arm separation, trunk forward–backward tilt, throwing-arm elevation angles, and the absolute and relative throwing procedure phase times. Videographic data of 51 male and 53 female discus throwers' competitive performances were captured during major meets. The three-dimensional coordinates of 21 body landmarks and the discus were obtained for each thrower's best trial using direct linear transformation. The technical parameters were reduced from the three-dimensional data at six critical instants during the throwing procedure. Hierarchical stepwise multiple regression analyses were performed to determine the relative influence of linear combinations of the technical parameters on discus throwing performance. Specific techniques associated with linear combinations of certain technical parameters were identified using canonical correlations. Males and females were analysed separately. Suggestions for controlling the height of release and the vertical component of the speed of release using an effective technique are made.     

对我国优秀男子铁饼运动员投掷技术的运动学分析

通过对我国优秀男子铁饼运动员旋转掷铁饼技术的速度结构特征和动作结构特征的初步分析,发现我国男子铁饼运动员与国外优秀运动员的主要差距是双支撑起转阶段和旋转阶段铁饼的速度损失较大。腾空和过渡时间长、肩髋柔韧性差、最后用力时机晚等是影响我国运动员铁饼速度发挥的主要因素。     

The relationship between discus throwing performance and combinations of selected technical parameters

The aim of this study was to determine the relationship between discus throwing performance and the following technical parameters: hip-shoulder and shoulder-arm separation, trunk forward-backward tilt, throwing-arm elevation angles, and the absolute and relative throwing procedure phase times. Videographic data of 51 male and 53 female discus throwers' competitive performances were captured during major meets. The three-dimensional coordinates of 21 body landmarks and the discus were obtained for each thrower's best trial using direct linear transformation. The technical parameters were reduced from the three-dimensional data at six critical instants during the throwing procedure. Hierarchical stepwise multiple regression analyses were performed to determine the relative influence of linear combinations of the technical parameters on discus throwing performance. Specific techniques associated with linear combinations of certain technical parameters were identified using canonical correlations. Males and females were analysed separately. Suggestions for controlling the height of release and the vertical component of the speed of release using an effective technique are made.     

Sequences of upper and lower extremity motions in javelin throwing

Javelin throwing is technically demanding. Sequences of upper and lower extremity motions are important for javelin throwing performance. The purpose of this study was to determine the general sequences of upper and lower extremity motions of elite male and female javelin throwers. Three-dimensional kinematic data were collected for 32 female and 30 male elite javelin throwers during competitions. Shoulder, elbow, wrist, hip, knee, ankle, lower trunk, and upper trunk joint and segment angles were reduced for the best trial of each participant. Beginning times of 6 upper extremity and 10 lower extremity joint and segment angular motions were identified. Sequences of the upper and lower extremity motions were determined through statistical analyses. Upper and lower extremity motions of the male and female elite javelin throwers followed specific sequences (P?≤?0.050). Upper extremity motions of the male and female elite javelin throwers did not follow a proximal-to-distal sequence as suggested in the literature. Male and female elite javelin throwers apparently employed different sequences for upper and lower extremity motions (P?相似文献   

Comparison of sequence of trunk and arm motions between short and long official distance groups in javelin throwing

The purpose of this study was to determine the effects of sequences of the trunk and arm angular motions on the performance of javelin throwing. In this study, 32 male and 30 female elite javelin throwers participated and were separated into a short official distance group or a long official distance group in each gender. Three-dimensional coordinates of 21 body landmarks and 3 marks on the javelin in the best trial were collected for each subject. Joint center linear velocities and selected trunk and arm segment and joint angles and angular velocities were calculated. The times of the initiations of the selected segment and joint angular motions and maximum angular velocities were determined. The sequences of the initiations of the selected segment and joint angular motions and maximum angular velocities were compared between short and long official distance groups and between genders. The results demonstrated that short and long official distance groups employed similar sequences of the trunk and arm motions. Male and female javelin throwers employed different sequences of the trunk and arm motions. The sequences of the trunk and arm motions were different from those of the maximal joint center linear velocities.     

我国女子铁饼优秀运动员过渡和最后用力阶段技术动力学及运动学的特征

时目前我国3名优秀女子铁饼运动员投掷技术进行同步研究发现,宋爱民存在腾空时间短、重心高、右脚着地早、上下肢扭紧差,最后用力阶段重心向投掷方向移动速度快、左右脚在垂直方向和前后方向的力较大、力量的向前行较好;孙太凤缓冲时间较短、右腿蹬伸充分、垂直方向和向前的力量较大;李艳凤过渡阶段上下肢扭紧好、身体后倾角度大、右脚着地对地面冲击力大、左右方向的力较大、力量在左右腿之间移动幅度大、没有转化为向前或者垂直方向的力量,向前性差,蹬伸不充分.     

Athletics

The purposes of this study were to investigate (1) the relationships between official distance and selected ground reaction measures during discus throwing; and (2) the relationships between selected ground reactions and selected lower extremity joint kinetics. Three high‐speed video cameras and three force plates were used to collect three‐dimensional videographic and force plate data in this study. An inverse dynamic model was used to determine the lower extremity kinetics. Multiple regression analyses were conducted to determine relationships of the selected kinematic and kinetic measures with the official distance. Official distance was significantly correlated with ground reaction forces on the left foot during the first single‐support phase, on the right foot during the second single‐support phase and delivery phase, and on the left foot during the delivery phase. Also, the right‐hip extension and internal rotation moments and left‐knee extension moment during the delivery phase were significantly correlated with official distance. These results suggest that discus throwers should drive vigorously forward during the first single‐support phase and increase the landing impact force on the right foot after flight. Also they should increase forward and rightward ground reaction force on the right foot and backward and vertical force on the left foot by powerful right‐hip extension and internal rotation and left‐knee extension during the delivery phase. These results provide critical information regarding the training of discus‐throwing techniques, and the direction of future biomechanical studies on this event.     

旋转掷铁饼技术中肩、髋、铁饼及人体重心的时空特征研究

运用近景动态立体摄像的方法 ,对我国优秀女子运动员完成旋转掷铁饼技术时的肩、髋、铁饼及人体重心的时空特征进行了三维分析。表明不同时空的肩、髋、铁饼及人体重心处于不同的位置 ,是与铁饼技术要求紧密相关的 ,破坏了各个时空中肩、髋、铁饼及人体重心的时空结构势必会影响掷铁饼技术、速度和最后的运动成绩 ;铁饼速度与人体重心速度的变化反映了旋转掷铁饼技术的节奏特征     

力量素质与铁饼成绩的灰色关联分析

本文通过对天津体院男、女铁饼运动员,集训队部分男铁饼运动员以及优秀铁饼运动员张景龙的各项力量素质与铁饼成绩的灰色关联分析,找出了影响不同类型运动员铁饼成绩的主要优势因素;并通过对他们有关力量素质的对比分析,论述了各类铁饼运动员应有不同的中心训练任务和训练方法。     

Reply to Glazier: “Comment on ‘Influence of shaft length on golf driving performance’”

Abstract

In this study we compared the kinematic features of the throwing motion between young baseball players of different age groups. Forty‐four Japanese baseball players aged 6.1 to 12.3 years who regularly played baseball, including pitchers and position players, had their throwing actions analyzed three‐dimensionally using high speed videography. Of this sample, 26 players aged above 9 years of age were categorized as the senior group, while the remaining 18 were categorized as the junior group. Senior group throwers had greater height and body mass, and produced a greater ball speed than junior group throwers. The throwing arm movement of senior group throwers was similar to that of adult skilled players. However, in the junior group throwers, the shoulder horizontal adduction angle was larger during the arm acceleration phase, and the maximum angular velocities of elbow extension and shoulder internal rotation occurred later than in senior group throwers. These results indicate that players aged above 9 years can acquire a mature throwing arm movement, while players younger than that will use an immature motion. A possible reason why these differences were shown is that the official baseball is relatively heavy for junior group throwers; they would be better advised to use a lighter ball in throwing practice.     

Shoulder and elbow kinematics in throwing of young baseball players

In this study we compared the kinematic features of the throwing motion between young baseball players of different age groups. Forty-four Japanese baseball players aged 6.1 to 12.3 years who regularly played baseball, including pitchers and position players, had their throwing actions analyzed three-dimensionally using high speed videography. Of this sample, 26 players aged above 9 years of age were categorized as the senior group, while the remaining 18 were categorized as the junior group. Senior group throwers had greater height and body mass, and produced a greater ball speed than junior group throwers. The throwing arm movement of senior group throwers was similar to that of adult skilled players. However, in the junior group throwers, the shoulder horizontal adduction angle was larger during the arm acceleration phase, and the maximum angular velocities of elbow extension and shoulder internal rotation occurred later than in senior group throwers. These results indicate that players aged above 9 years can acquire a mature throwing arm movement, while players younger than that will use an immature motion. A possible reason why these differences were shown is that the official baseball is relatively heavy for junior group throwers; they would be better advised to use a lighter ball in throwing practice.     

对我国优秀女子铁饼运动员投掷技术的运动学分析

目前,我国优秀女子铁饼运动员的成绩与世界一流水平相比,存在不少差距。本文将第6届全运会优秀女子铁饼运动员的技术动作分为4个时相,对其运动学特征进行解析,为改进技术动作、提高运动成绩提供参考依据。     

Changing throwing pattern: instruction and control parameter

The purpose of this study was to determine the effects of instruction and scaling up a control parameter (velocity of throw) on changes in throwing pattern. Sixty adult female throwers (ages 20-26 years) were randomly placed into one offour practice conditions: (a) scale up on velocity with no instruction, (b) maintain constant velocity with no instruction, (c) maintain constant velocity with instruction, and (d) scale up on velocity with instruction. Participants in each condition were required to practice throwing with the nondominant arm twice per week for 5 weeks (10 sessions). Practice consisted of 20 throws per session. Participants in conditions including instruction were encouraged to rotate the trunk in an attempt to take advantage of the order parameter. Analysis indicated that each condition improved relative to use of the open kinetic chain. However, participants who increased velocity were more likely to attain maximum use of the order parameter with less practice. Additionally, throwers who increased velocity without instruction attained an optimal pattern of complete distal lag one session earlier than those who increased velocity with instruction. Data indicated that for those conditions without instruction, hand to forearm lag (H-F lag) occurred before humeral lag. It was concluded that emphasizing proximal movement (trunk rotation) without increasing velocity does not result in a final pattern that uses H-F lag.     

Release parameters at the foul line and the official result in javelin throwing

Range in javelin throwing is determined by the release parameters and aerodynamic factors. The current study was designed to investigate the effects of release speed, release angle and uncorrected angle of attack measured at the foul line on the official javelin throwing result. The data were collected in international competitions for 26 elite male and 15 elite female javelin throwers (total 248 throws). Multiple regression models were constructed to predict the range of throw for a) individual throwers, b) a group of throwers using the mean value for each thrower in the analysis, and c) all individual throws registered for each gender separately. The data collection was carried out using a computerised photocell gate that consists of two invisible infrared walls two metres apart, perpendicular to the throwing direction. Release speed was found to have the highest correlation with the official throwing result. The three release parameters accounted for 56% of the variance in the official result for the male and 51% for the female throwers. For individual male and female throwers, the variance explained by the model was between 46 and 87%. Among the individual male throwers an increase of 1 m.s-1 in the release speed from 29 to 30 m.s-1 was calculated to increase the official result between 2.12 to 6.14 m while among the female throwers the effect of increase from 24 to 25 m.s-1 in the release speed was from 2.25 to 3.68 m. The study emphasises the importance of investigating javelin throwing biomechanics on an individual thrower basis.     

Contributions of the muscular torques and motion-dependent torques to generate rapid elbow extension during overhand baseball pitching

Some studies have reported that overarm baseball pitching shows a proximal to distal sequential joint motion including a rapid extension of the elbow. It has been suggested that the rapid elbow extension just before ball release is not due to the action of the elbow extensor muscles, but the underlying mechanisms are not so clear. The purpose of this study was to determine the contributions of each joint muscular- and motion-dependent torques, including the upper trunk and throwing arm joints to generate the rapid elbow extension during baseball pitching. The right handed throwing motions of three baseball pitchers were recorded using five high-speed video cameras and the positional data were calculated using the direct linear transformation method. A throwing arm dynamic model of the upper trunk and throwing arm joints was then used, including 10 degrees of freedom, to calculate the throwing arm joint muscular-, throwing arm and upper trunk joint motion-, gravity-, and external force-dependent components that contribute to the maximum elbow extension angular velocity. The results showed that the rapid elbow extension was primarily due to the upper trunk counterclockwise rotation and shoulder horizontal adduction angular velocity-dependent torques. This study implied that the trunk counterclockwise rotators and shoulder horizontal adductors generate positive torques to maintain the angular velocities of the upper trunk counterclockwise rotation and shoulder horizontal adduction may play a key role in producing the rapid elbow extension.     

Kinetics of throwing arm joints and the trunk motion during an overarm distance throw by skilled Japanese elementary school boys

The purpose of this study was to investigate joint kinetics of the throwing arms and role of trunk motion in skilled elementary school boys during an overarm distance throw. Throwing motions of 42 boys from second, fourth, and sixth grade were videotaped with three high-speed cameras operating at 300 fps. Seven skilled boys from each grade were selected on the basis of throwing distance for three-dimensional kinetic analysis. Joint forces, torques, and torque powers of the throwing arm joints were calculated from reconstructed three-dimensional coordinate data smoothed at cut-off frequencies of 10.5–15 Hz and by the inverse dynamics method. Throwing distance and ball velocity significantly increased with school grade. The angular velocity of elbow extension before ball release increased with school grade, although no significant increase between the grades was observed in peak extension torque of elbow joint. The joint torque power of shoulder internal/external rotation tended to increase with school grade. When teaching the overarm throw, elementary school teachers should observe large backward twisting of trunk during the striding phase and should keep in mind that young children, such as second graders (age 8 years), will be unable to effectively utilise shoulder external/internal rotation during the throwing phase.     

A kinetic analysis of discus-throwing techniques

The purposes of this study were to investigate (1) the relationships between official distance and selected ground reaction measures during discus throwing; and (2) the relationships between selected ground reactions and selected lower extremity joint kinetics. Three high-speed video cameras and three force plates were used to collect three-dimensional videographic and force plate data in this study. An inverse dynamic model was used to determine the lower extremity kinetics. Multiple regression analyses were conducted to determine relationships of the selected kinematic and kinetic measures with the official distance. Official distance was significantly correlated with ground reaction forces on the left foot during the first single-support phase, on the right foot during the second single-support phase and delivery phase, and on the left foot during the delivery phase. Also, the right-hip extension and internal rotation moments and left-knee extension moment during the delivery phase were significantly correlated with official distance. These results suggest that discus throwers should drive vigorously forward during the first single-support phase and increase the landing impact force on the right foot after flight. Also they should increase forward and rightward ground reaction force on the right foot and backward and vertical force on the left foot by powerful right-hip extension and internal rotation and left-knee extension during the delivery phase. These results provide critical information regarding the training of discus-throwing techniques, and the direction of future biomechanical studies on this event.     

男子背向滑步推铅球最后用力阶段髋肩躯干转动的运动学特征研究

采用影像分析法、文献资料法、对比分析法等对3名优秀男子背向滑步推铅球选手最后用力时躯干动作变化进行研究与分析,以期掌握滑步推铅球运动员在最后用力过程中躯干转动的动作结构、速度变化等特征,对指导实际教学与训练有重要的现实意义.分析表明,在最后用力过程中,3名运动员的躯干动作是在前振的同时进行有序转动的复合运动.优秀铅球运动员的躯干转动技术表明,最后用力阶段.髋轴先于肩轴达到峰值速度,达到峰值后依次快速下降.在铅球出手瞬间躯干接近垂直状态,有一定程度的"前倾"或"后仰".躯干在过渡阶段的适当前振有利于左腿的积极着地,有利于铅球速度和整个身体重心速度的增加,进而缩短过渡阶段进入最后用力阶段的时间.     

Baseball

The purpose of this study was to quantify and compare kinematic, temporal, and kinetic characteristics of American and Korean professional pitchers in order to investigate differences in pitching mechanics, performance, and injury risks among two different cultures and populations of baseball pitchers. Eleven American and eight Korean healthy professional baseball pitchers threw multiple fastball pitches off an indoor throwing mound positioned at regulation distance from home plate. A Motion Analysis three‐dimensional automatic digitizing system was used to collect 200 Hz video data from four electronically synchronized cameras. Twenty kinematic, six temporal, and 11 kinetic variables were analyzed at lead foot contact, during the arm cocking and arm acceleration phases, at ball release, and during the arm deceleration phase. A radar gun was used to quantify ball velocity. At lead foot contact, the American pitchers had significantly greater horizontal abduction of the throwing shoulder, while Korean pitchers exhibited significantly greater abduction and external rotation of the throwing shoulder. During arm cocking, the American pitchers displayed significantly greater maximum shoulder external rotation and maximum pelvis angular velocity. At the instant of ball release, the American pitchers had significantly greater forward trunk tilt and ball velocity and significantly less knee flexion, which help explain why the American pitchers had 10% greater ball velocity compared to the Korean pitchers. The American pitchers had significantly greater maximum shoulder internal rotation torque and maximum elbow varus torque during arm cocking, significantly greater elbow flexion torque during arm acceleration, and significantly greater shoulder and elbow proximal forces during arm deceleration. While greater shoulder and elbow forces and torques generated in the American pitchers helped generate greater ball velocity for the American group, these greater kinetics may predispose this group to a higher risk of shoulder and elbow injuries.