Effects of phase ratio and velocity conversion coefficient on the performance of the triple jump

Abstract

Phase ratio is a measure of effort distribution in the triple jump. Hop-dominant, balanced, and jump-dominant techniques were three triple jump techniques defined based on phase ratio. The purpose of this study was to determine the effect of the phase ratio on the performance of the triple jump. Three-dimensional kinematic data of 13 elite male triple jumpers were obtained during a competition. Computer simulations were performed using a biomechanical model of the triple jump to optimise the phase ratio for the longest actual distance using each of the three techniques for a given athlete with altered velocity conversion coefficients. The velocity conversion coefficient affected which technique achieved the longest actual distance. The actual distance obtained using the hop-dominant technique was significantly longer than that obtained using the other two techniques (P = 0.007, P = 0.001) when the velocity coefficient was between 0.35 and 0.55. The actual distance obtained using the jump-dominant technique was significantly longer than that obtained using the other two techniques (P = 0.001, P = 0.002) when the velocity coefficient was between 0.80 and 1.30. No consistent optimum technique across participants and no significant difference in performance among the three techniques were found (P > 0.524) when the velocity coefficient was between 0.60 and 0.75.     

重新审度“三级跳远的极值与各跳最佳组合”的研究方法

本文根据三级跳远的技术和三跳相互间的约束特点,运用逐步回归方法建立了世界水平三级跳远成绩与三跳远度的非线性最佳数学模型,并得出不同水平的三跳最佳组合与最大远度的关系。同时,分析了各跳对三级跳远成绩的影响,为指导不同水平的三级跳远训练制定了控制模式。     

我国女子三级跳远运动员水平速度利用及损失诸因素的分析研究

运用文献资料法、调查访问法、高速摄影、光电测速、数理统计等研究方法 ,以揭示目前我国优秀女子三级跳运动员水平速度的损失及利用状况。指出三级跳远成绩与各跳水平速度高度相关 ,其三跳水平速度损失之和是衡量技术优劣的一个重要指标     

第11届全运会女子三级跳远运动员三跳技术的运动学分析

对参加第11届全运会田径比赛女子三级跳远决赛前8名运动员三跳技术的相关运动学参数进行研究,结果表明:我国女子三级跳远运动员助跑绝对速度和起跳速度利用率较差,只有8.96 m/s和95.5%,与世界女子三级跳运动员的9.41 m/s和98.2%相比,差异具有显著性(P<0.01);起跳脚着地与离地瞬间身体重心水平速度较差,只有8.71 m/s,与世界选手的9.33 m/s相比,差异有非常显著性(P<0.01);单足跳与跨步跳时的身体重心腾起角度适宜,分别为(17.19±4.37)°、(15.07±4.12)°,但最后跳跃的身体重心腾起角过大(23.57±4.12)°,超过世界运动员的16°~20°;三跳的支撑总时间较长,起跳效果不理想。     

现代三级跳远的最佳三跳比例的探讨

本文以具有当今世界水平的三级跳远选手的30组测试成绩为依据,运用二次响应面回归模型,研究了三级跳远成绩与三跳远度的关系。并用冷嵴分析的方法,给出了使三级跳远成绩达到最大值的最佳三跳组合(比例)模式。     

Isokinetic Leg Flexion and Extension Strength of Elite Adolescent Female Track and Field Athletes

Abstract

Sixty-two elite adolescent (age: 16.39 ± 1.62 yrs) female track and field athletes volunteered to be measured isokinetically for peak torque of the leg flexors and extensors. The sample included 16 throwers, 11 jumpers, 12 middle-distance runners (> 400 m), and 23 sprinters. A Cybex II isokinetic dynamometer was used to measure dominant leg strength at 180°/sec. One-way ANOVA revealed significant between group differences for absolute flexion and extension (Nm), extension/body weight (Nm/Kg), and extension/lean body weight (Nm/Kg). Scheffe post-hoc comparisons showed that, for absolute leg extension strength, throwers were stronger than middle-distance runners (by 54.4%), sprinters (35.6%), and jumpers (23.6%). For absolute leg flexion movements, throwers were stronger than middle distance runners (37.4%) and sprinters (32.1%). Jumpers had greater extension peak torque values than middle-distance runners relative to body weight (14.0%), and throwers were stronger than middle-distance runners for extension/lean body weight (14.9%)). No other comparisons were significant. However, when strength was expressed relative to body weight or lean body weight, there were few differences between events for flexion or extension. Given that absolute strength scores were correlated with body weight and lean body weight, peak torque/body weight or peak torque/lean body weight may be more sensitive than absolute values as indicators of underlying factors (such as training status or fiber type composition) responsible for the differences in muscular strength between groups.     

我国优秀女子三级跳远运动员二、三跳起跳技术运动学特征

对8 名国内优秀女子三级跳远运动员二、三跳起跳技术影片解析结果表明,第二跳起跳时所获得的垂直速度小,腾起角小,这与起跳蹬伸时机晚和蹬伸不充分有关,同时与摆动腿大小腿折叠不紧、摆动速度慢和摆动幅度小有关。第三跳起跳过程中水平速度损失较多,但也获得了较大的垂直速度,这与起跳时着地角小和起跳角大及着地过程中脚扒地速度慢有关,同时与摆动腿摆动速度慢和摆动幅度小有关。8 名运动员第二跳距离百分比偏小。     

Kinematic and kinetic differences in the execution of vertical jumps between people with good and poor ankle joint dorsiflexion

Abstract

The aim of the present study was to investigate the kinematic and kinetic differences in the execution of vertical jumps between individuals with good and poor ankle dorsiflexion. Fifteen physical education students were assigned to the flexible group (FG), while another 15 were assigned to the inflexible group (IFG). The two groups executed countermovement jumps (CMJ) and drop jumps from a 60 cm height (DJ60). For the CMJ, the FG jumped higher (32.0 ± 4.0 cm vs. 30.2 ± 4.9 cm, P = 0.27) and used a greater range of motion in all leg joints. The IFG jumpers raised their heels off the ground and had a greater horizontal distance between the centre of mass of the trunk and the centre of the hip joint (L_CMh 25.6 ± 3.4 cm vs. 30.9 ± 4.3 cm, P < 0.001). In the DJ60 the FG jumped higher (22.4 ± 5.9 cm vs. 19.5 ± 4.6 cm, P = 0.14) with a greater vertical shift of the body centre of mass (BCM) (S = 0.45 ± 0.11 cm vs. 0.36 ± 0.05 cm, P < 0.01) and better joint coordination. The IFG jumpers changed the position of their trunk and heels depending on the jump type. Trainers should reconsider the technical issues of vertical jumps according to the flexibility of the ankle joint.     

中外优秀女子三级跳远运动员第三跳技术的运动学比较

运用高速摄影法、文献资料法和灰色理论关联度分析法对我国优秀女子三级跳远运动员第三跳的技术进行研究，并与世界优秀选手技术进行对比分析发现：我国优秀女子三级跳远运动员助跑绝对速度较低，第三跳的距离较近，并且第三跳垂直分速度和腾起角度较小。提高我国运动员的绝对速度能力，应是我国女子三级跳远训练的重点；改进和加强弱腿跳远的技术和能力，也是我国女子三级跳远训练亟待解决的课题。     

Late information pick-up is preferred in basketball jump shooting

Abstract

In this study we examined the timing of optical information pick-up in basketball jump shooting using an intermittent viewing technique. We expected shooters to prefer to look at the basket as late as possible under the shooting style used. Seven experts with a high shooting style and five experts with a low shooting style took 50 jump shots while wearing liquid-crystal glasses that opened and closed at pre-set intervals. In principle, under this constraint, the participants could control when they saw the basket by actively modulating the timing of their movements. Analyses of the phasing of the movements relative to the events defined on the glasses revealed that low-style shooters preferred to see the basket just before the ball passed their line of sight, whereas high-style shooters tended to view the basket from underneath the ball after it passed their line of sight. Thus, most shooters preferred to pick up optical information as late as possible given the adopted shooting style. We conclude that, in dynamic far aiming tasks such as basketball jump shooting, late pick-up of optical information is critical for the successful guidance of movements.     

Relationship between split-step timing and leg stiffness in world-class tennis players when returning fast serves

ABSTRACT

This study investigated split-step timing when returning serves and whether this timing is related to neuromechanical capabilities in world-class tennis players. In Experiment 1, the split-step timing of four groups of world-class players (male and female ATP/WTA seniors, and ITF juniors) was measured on court when returning serves of the same level players. The four groups initiated the split-step at a similar time, starting around the time ball-racket contact in the serve stroke and landed when early ball-flight information was available. In Experiment 2, the neuromechanical capabilities (leg stiffness and vertical jump performance) of a group of world-class players and three groups of less-skilled tennis players were examined. The results showed an increase in leg stiffness with an increase in the level of expertise. A cross-experiment analysis in world-class male players (ATP/ITF, n = 10) revealed that the timing of initial foot movement was significantly correlated with the leg stiffness (r² = 0.54), with later lateral step after the serve in the players who had higher stiffness. The findings support the hypothesis that world-class tennis players adapt perceptual-motor control on the basis of their neuromechanical capabilities and maximise the time before initiating their interceptive action to rely on more reliable information.     

背越式跳高运动员摆动腿技术对起跳效果的影响

跳高是体能主导类项目,但对技术要求较高的运动项目,跳的更高是每位跳高运动员所追求的目标。目前,我国跳高项目举步维艰的现实让我们不禁思考如何改进此项目在技术上的不足。本文着重对跳高运动员摆动腿技术的研究成果进行总结和归纳,提取背越式跳高运动员摆动腿技术的有效训练方法和经验,为跳高技术教学与训练提供理论和实践依据。     

世界男子三级跳远技术现状及发展趋势的研究

基于世界20名优秀三级跳远的男运动员资料,总结了不同阶段世界男子三级跳远的技术,归纳了男子三级跳远技术可分为4种类型,分别是自由式,高跳型、平跳型和速度-平跳型.文章还提出了世界男子三级跳远发展的新趋势.     

男子三级跳远运动员起跳腿“拉长-缩短周期”收缩能力的研究

运用运动生物力学的方法对两种不同水平的男子三级跳远运动员，进行了起跳腿的“拉长缩短周期，，收缩能力的对比研究。结果表明，三级跳远运动员起跳腿的肌肉反应特性，是影响三级跳远成绩的一个重要因素，水平高的三级跳远运动员起跳腿“拉长一缩短周期”收缩能力总体上高于低水平运动员；髋关节并不是缓?中外界负荷的主要关节；膝关节的退让工作能力对起跳效果有很大的影响；不同水平运动员之间，踝关节伸肌群的退让工作能力不具显著性差异；踝关节的缓?中幅度很大程度上是受上板水平速度的影响；高水平运动员的踝关节蹬伸平均角速度要大于低水平运动员的。     

Haptic perception accuracy depending on self-produced movement

Abstract

This study measured whether self-produced movement influences haptic perception ability (experiment 1) as well as the factors associated with levels of influence (experiment 2) in racket sports. For experiment 1, the haptic perception accuracy levels of five male table tennis experts and five male novices were examined under two different conditions (no movement vs. movement). For experiment 2, the haptic afferent subsystems of five male table tennis experts and five male novices were investigated in only the self-produced movement-coupled condition. Inferential statistics (ANOVA, t-test) and custom-made devices (shock & vibration sensor, Qualisys Track Manager) of the data were used to determine the haptic perception accuracy (experiment 1, experiment 2) and its association with expertise. The results of this research show that expert-level players acquire higher accuracy with less variability (racket vibration and angle) than novice-level players, especially in their self-produced movement coupled performances. The important finding from this result is that, in terms of accuracy, the skill-associated differences were enlarged during self-produced movement. To explain the origin of this difference between experts and novices, the functional variability of haptic afferent subsystems can serve as a reference. These two factors (self-produced accuracy and the variability of haptic features) as investigated in this study would be useful criteria for educators in racket sports and suggest a broader hypothesis for further research into the effects of the haptic accuracy related to variability.     

李延熙打破三级跳远亚洲记录技术特征分析

本文通过文献资料法、录像分析法等方法对我国著名三级跳远运动员李延熙在2009年8月柏林世锦赛和2009年11月山东西柳举行的全运会三级跳远的比赛录像资料与世界著名三级跳远运动员爱德华兹在第五届世界田径锦标赛决赛创纪录一跳的录像资料进行比较分析,分别通过比较两者三次比赛的助跑速度。三跳的腾起角、速度利用率,膝角变化、和三跳比例等技术参数,得出李延熙打破全国及亚洲记录的真正原因;同时指出与世界最高水平的差距,为李延熙今后进一步提高提供技术参考。     

对助跑及三跳水平速度与男子三级跳远成绩的关联分析

通过对我国优秀男子三级跳远运动员助跑及三跳水平速度的测试与关联分析,揭示了助跑、三跳水平速度及速度损失等因素与三级跳远成绩的内在联系,提出了我国男子三级跳远技术的发展方向。     

优秀女子三级跳远运动员速度变化特点的研究

主要采用摄像、录象解析法和文献资料法,对我国部分优秀女子三级跳远运动员在试跳过程中速度变化的特点以及每一跳速度变化情况进行分析,同时与世界优秀运动员进行对比。探讨女子三级跳远技术中各跳之间速度分配的特点。     

Changes in long jump take-off technique with increasingrun-up speed

Abstract

The aim of this study was to determine the influence of run-up speed on take-off technique in the long jump. Seventy-one jumps by an elite male long jumper were recorded in the sagittal plane by a high-speed video camera. A wide range of run-up speeds was obtained using direct intervention to set the length of the athlete's run-up. As the athlete's run-up speed increased, the jump distance and take-off speed increased, the leg angle at touchdown remained almost unchanged, and the take-off angle and take-off duration steadily decreased. The predictions of two previously published mathematical models of the long jump take-off are in reasonable agreement with the experimental data.     

The Relationship of Isokinetic Torque at Two Speeds to the Vertical Jump

Abstract

The relationship between the ability to develop leg torque and performance in the vertical jump was investigated in 29 female athletes. Each subject's leg flexion, leg extension, and foot plantar flexion peak torque was determined isokinetically on a Cybex at angular velocities of 30 degrees/second and 180 degrees/second. The vertical jump was determined for each subject and correlations among the measures of torque and the vertical jump were calculated. Although the ability to produce leg power as exemplified by the vertical jump was significantly correlated with peak torque at the fast angular velocity but was not significantly correlated with peak torque at the slow angular velocity, the correlations were so low it was concluded that there was little if any relationship between torque at a fast or slow angular velocity and the ability to vertically jump.