Consistency of performances in the Tkatchev release and re-grasp on high bar

The Tkatchev on the high bar is a release and re-grasp skill in which the gymnast rotates in a direction during flight opposite to that of the preceding swing. Since the release window is defined as the time during which the gymnast has appropriate linear and angular momentum to ensure the bar can be re-grasped, it was speculated that the release windows for this skill would be smaller than for dismounts that are less constrained. One senior male gymnast competing at national standard performed 60 Tkatchev trials. A four-segment planar simulation model of the gymnast and high bar was used to determine the release windows in 10 successful and 10 unsuccessful performances of the Tkatchev recorded using a Vicon motion analysis system. Model parameters were optimized to obtain a close match between simulations and recorded performances in terms of rotation angle (1 degree), bar displacements (0.01 m), and release velocities (1%). Each matched simulation was used to determine the time window around the actual point of release for which the model had appropriate release parameters to complete the Tkatchev successfully. The release windows for the successful trials were small compared with those of dismounts. The unsuccessful trials were associated with later release and later timing of the actions at the shoulders and hips.     

Investigating optimal technique in the presence of motor system noise: application to the double layout somersault dismount on high bar

Minimising joint torque is often used as an optimisation criterion when investigating human movement. Alternatively, an aspect of performance may be chosen to be maximised when investigating sporting movements. The aim of the study was to optimise the technique in the backward giant circle prior to a double layout somersault dismount from the high bar using various criteria to determine which best characterised the technique adopted by a gymnast. Ten recorded gymnast trials were used to determine bar release parameters and the level of noise in the gymnast’s movements. A computer simulation model of a gymnast and bar was used to optimise giant circle technique under three criteria: minimising joint torques, maximising the release window and maximising success in the presence of motor system noise. Local and global optimisations of technique were performed using the three criteria starting from the average technique of the 10 recorded trials. All global optimum solutions diverged from the gymnast’s technique. The local optimum for maximising success in the presence of noise had a success rate comparable with the global optimum (98% vs. 100%, respectively). It is concluded that the gymnast’s technique is characterised by maximising success despite operating with motor system noise.     

Optimization of the felge on parallel bars

The felge, or undersomersault, on parallel bars has become an important skill in men's artistic gymnastics as it forms the basis of many complex variations. To receive no deductions from the judges, the felge must be performed without demonstrating the use of strength to achieve the final handstand position. Two male gymnasts each performed nine trials of the felge from handstand to handstand while data were recorded using an automatic motion capture system. The highest and lowest scoring trials of each gymnast, as determined by four international judges, were chosen for further analysis. The technique used by each gymnast was optimized using a computer simulation model so that the final handstand position could be achieved with straight arms. Two separate optimizations found different techniques identified in the coaching literature that are used by gymnasts. Optimum simulations resulted in improved performances through a combination of increased vertical velocity and height of the mass centre at release. Although the optimum technique found close to the gymnasts' own technique was more demanding in terms of the strength required, it offered the potential for more consistent performance and future developments in skill complexity.     

单杠直体后空翻二周越杠再握动作研究

单杠直体后空翻二周越杠再握动作是近年来新出现的超E组高难度动作,采用运动生物力学研究方法对江苏体操队队员王哲攻克这一动作的全过程进行跟踪研究。在他掌握该动作的基础上,又根据有关单杠“飞行”动作理论研究的成果,通过计算机模拟,探索了完成该动作的最佳化问题。     

Functional phases and angular momentum characteristics of Tkatchev and Kovacs

Understanding the technical requirements and underlying biomechanics of complex release and re-grasp skills on high bar allows coaches and scientists to develop safe and effective training programmes. The aim of this study was to examine the differences in the functional phases between the Tkatchev and Kovacs skills and to explain how the angular momentum demands are addressed. Images of 18 gymnasts performing 10 Tkatchevs and 8 Kovacs at the Olympic Games were recorded (50 Hz), digitised and reconstructed (3D Direct Linear Transformation). Orientation of the functional phase action, defined by the rapid flexion to extension of the shoulders and extension to flexion of the hips as the performer passed through the lower vertical, along with shoulder and hip angular kinematics, angular momentum and key release parameters (body angle, mass centre velocity and angular momentum about the mass centre and bar) were compared between skills. Expected differences in the release parameters of angle, angular momentum and velocity were observed and the specific mechanical requirement of each skill were highlighted. Whilst there were no differences in joint kinematics, hip and shoulder functional phase were significantly earlier in the circle for the Tkatchev. These findings highlight the importance of the orientation of the functional phase in the preceding giant swing and provide coaches with further understanding of the critical timing in this key phase.     

How do technique and coordination change during learning of a whole-body task: Application to the upstart in gymnastics

ABSTRACT

When learning swinging skills on a bar there has been conflicting advice in the research literature regarding whether to coach the “gold standard” technique to novices. The present study aimed to determine how technique (joint angle time histories) and (inter-limb) coordination changed as novice gymnasts learned a fundamental gymnastics skill (the upstart). It was hypothesised that both technique and coordination would become more like an expert as learning progressed. Eight novice gymnasts, unable to perform an upstart, underwent four months of training, with the number of successful upstarts out of 10 recorded at the start and then every month subsequently. In the first and last sessions motion capture was used to determine joint kinematics. Root mean squared differences for the joint angle time histories and continuous relative phase at the shoulder and hip were calculated between the novices and an expert gymnast. As training progressed technique and coordination became more like the expert gymnast. The more successful novices were better able to time their actions within the swing than the less successful novices. Gymnastics coaches teach towards a “gold standard” technique since being successful at the skill is not the only goal, as considerations for future skill development are made.     

The double back salto dismount from the parallel bars

The purpose of this study was to identify those mechanical determinants or their trends that distinguished a gymnast's best performance of the double back salto dismount on parallel bars from those judged to be inferior. Dismounts, in the tucked position, by nine Canadian gymnasts were analysed. Unique to this study was the inclusive analysis of multiple performances of the same skill by these athletes. It was felt that within-subject comparisons would reveal the kinematic variables on which the gymnast may focus in order to achieve their best performances. A non-parametric median sign test was used to compare mechanical variables, within subjects, between the dismount judged the best and those dismounts awarded a lower score. Three judges judged each dismount. In comparison to poorer performances of the dismount, statistical analyses revealed that athlete's best performances were characterised by (1) a higher release point, more vertical velocity yet with less angular momentum at take-off, (2) greater height, with a tighter and earlier tuck position during the flight phase, and (3) a greater range of motion and a more compact squat position at landing (all p's < .06).     

Musculoskeletal work preceding the outward and inward Tkachev on uneven bars in artistic gymnastics

Outward facing Tkachevs on uneven bars have been the traditional technique employed by artistic gymnasts. Changes in bar spacing and judging have increased the popularity of the inward version of the skill, in which the gymnast faces towards the low bar as she straddles over the high bar. The purpose of this study was to compare these two variants of the women's Tkachev to examine the influence of the positioning of the low bar on the musculoskeletal demands placed on the gymnast. 3-D DLT reconstructed data sets from digitised video images of straddle Tkachevs performed at the 2000 Sydney Olympics were analysed. Five performances of each variant were compared using kinematics and inverse dynamics. Mean hip and shoulder kinematics were similar for both variants of the Tkachev, but for the inward, gymnasts released later, travelled higher and re-grasped earlier than for the outward. Hip joint moments were similar for both variants while shoulder moments were different. Total musculoskeletal demands were similar for both variants, although the distribution was markedly different with the shoulders contributing positively for the outward and negatively for the inward. Implications for training specificity, along with potential future developments for the inward variant, have been highlighted.     

A dynamic approximation of balanced gymnastics landings

A gymnast can balance after an uneven parallel bar dismount by contacting the ground with an appropriate body position and angular velocity. Balanceable gymnastics landings were predicted by dividing landing into two parts: a short duration impact phase when foot-mat contact forces are high, and a subsequent longer balancing phase during which the gymnast exerts active control at the joints to attenuate the resulting post-impact velocities and achieve a desired motionless terminal configuration. This paper identifies controllable sets of pre-impact landing positions and velocities for a typical female collegiate gymnast that are feasible targets for the end of flight following a single- and double-backward somersault uneven bar dismount with forward mass centre (CM) velocity. Simple algebraic impulse-momentum models for the impact phase determine impulses necessary to stop the feet and slow angular velocity. After impact, a dynamic analysis is needed to determine stability because non-negligible post-impact angular and linear velocities are possible. For almost all successfully balanced landings, ground contact occurs with the CM positioned above the feet and between the toe and heel, because the linear impact impulses that stop the feet also contribute to an angular impulse that slows angular momentum. Only at the largest pre-impact angular velocities following a double-somersault dismount can contact occur with the CM in front of the toe. The gymnast is in balanceable preimpact orientations longer when rotating more slowly and with a smaller angular momentum; therefore balance may be more likely after performing a single-somersault dismount with a large moment of inertia.     

论艺术体操运动员的智力因素和非智力因素

艺术体操运动员的成功不仅决定于她们的技战术 ,还决定于智力水平 ,而非智力因素对她们能否取得优异成绩也举足轻重。既提高艺术体操运动员的操作思维 ,同时又提高她们的语言思维能力是提高艺术体操运动员智力的明智之举 ;兴趣、意志、情感、动机、性格等是影响艺术体操走向成功之路最重要的非智力因素     

江苏运动员刘鼎赫单杠直体特卡切夫腾越的运动学分析

直体特卡切夫腾越是单杠最有代表性的技术动作,运用SONY PC330高速摄影机,拍摄了江苏省体操队刘鼎赫完成该动作的成功与失败动作,运用Ariel运动分析软件从运动生物力学角度,对其动作技术的各个环节进行研究讨论,找出各个动作技术环节的关键因素,以期为运动员的训练提供一些参考。     

男子体操山羊全旋挺胯侧伸技术的训练方法

通过多年的教学实验和潜心研究,对山羊全旋教学进行了许多训练方法上的尝试,并获得了比较满意的效果。研究结果表明：从运动员身体素质、年龄的差异分别引导,寻找全旋的节奏感觉,能较快的掌握侧伸挺胯技术的要领,经过一段时间的强化、系统的训练,全旋弧度可达到明显的效果。     

A toy model that predicts the qualitative role of bar bend in a push jerk

In this work, we describe a simple coarse-grained model of a barbell that can be used to determine the qualitative role of bar bend during a jerk. In simulations of this model, we observed a narrow time window during which the lifter can leverage the elasticity of the bar in order to lift the weight to a maximal height. This time window shifted to later times as the weight was increased. In addition, we found that the optimal time to initiate the drive was strongly correlated with the time at which the bar had reached a maximum upward velocity after recoiling. By isolating the effect of the bar, we obtained a generalized strategy for lifting heavy weight in the jerk.     

Influence of longswing technique on the kinematics and key release parameters of the straddle Tkachev on uneven bars

Tkachev on uneven bars is a release and re-grasp skill performed using variations of preparatory longswing techniques; the reasons why different techniques are chosen remains unclear. This study examined kinematic and key release parameters specific to three distinct techniques with the aim of understanding the relative benefits of each. During two international artistic gymnastics competitions six arch, straddle and pike longswings preceding the straddle Tkachev were recorded using twin video cameras. Calibration and movement images were digitised and reconstructed using 3D DLT. Shoulder and hip angular kinematics, angular momentum and key release parameters were compared between techniques. In the arch longswing, the first and second hip functional phases began significantly earlier than the straddle or pike. No significant differences were established for release parameters although large effect sizes for horizontal release velocity and angular momenta about the mass centre and bar were reported between the arch and other two variants. Therefore, the arch variant may provide the opportunity to develop more complex combinations following the Tkachev. Providing insight into mechanical advantages of specific longswing techniques, and highlighting those that elicit desirable characteristics offers the potential to provide coaches with objective data on technique selection and ultimately skill development.     

Influence of longswing technique on the kinematics and key release parameters of the straddle Tkachev on uneven bars

Tkachev on uneven bars is a release and re-grasp skill performed using variations of preparatory longswing techniques; the reasons why different techniques are chosen remains unclear. This study examined kinematic and key release parameters specific to three distinct techniques with the aim of understanding the relative benefits of each. During two international artistic gymnastics competitions six arch, straddle and pike longswings preceding the straddle Tkachev were recorded using twin video cameras. Calibration and movement images were digitised and reconstructed using 3D DLT. Shoulder and hip angular kinematics, angular momentum and key release parameters were compared between techniques. In the arch longswing, the first and second hip functional phases began significantly earlier than the straddle or pike. No significant differences were established for release parameters although large effect sizes for horizontal release velocity and angular momenta about the mass centre and bar were reported between the arch and other two variants. Therefore, the arch variant may provide the opportunity to develop more complex combinations following the Tkachev. Providing insight into mechanical advantages of specific longswing techniques, and highlighting those that elicit desirable characteristics offers the potential to provide coaches with objective data on technique selection and ultimately skill development.     

Biomechanical similarities of progressions for the longswing on high bar

Based on specificity of training and biomechanical analysis, the aim of this study was to develop a method to rank selected progressions for learning the longswing on high bar. Four members of the Men's National Gymnastics Squad were recorded (50 Hz) performing three series of five longswings and eight progressions. Real world co-ordinates from the digitized data were determined using two-dimensional direct linear transformation. Biomechanical similarity between the functional phases of the longswing and the corresponding phases of the progressions were calculated. The functional phases were described as a hyperextension to flexion of the hip and hyperflexion to extension of the shoulder joints as the gymnast passed underneath the bar. Using a combined score of 'Difference' and movement 'Variability' a 'Specificity score' was calculated for hip and shoulder angular displacements and velocities. An overall score based on the average of the four scores provided a ranked list of progressions based on their similarity to the target skill. The progression that showed the greatest similarity to the biomechanics of the longswing, and was therefore ranked first, was the chalked bar pendulum swing. The least similar progression, and, therefore, eighth ranked, was the chalked bar bent knee longswing. The hip kinematics were found to contribute most to the overall differences because the performance requirements of these progressions emphasize an increase in hip flexion during the ascending phase. The method described provides a means to quantify and rank progressions based on their kinematic similarity to the longswing.     

单杠“后空翻”一周半越杠再握动作的生物力学分析

本文通过影片解析方法对江苏体操队田家勤在1986年全国体操锦标赛的预、决赛中成功和失败的“后空翻”一周半越杠再握动作进行了技术诊断,探讨了该动作的一般规律,并根据有关单杠“飞行”动作理论研究的成果,通过计算机模拟,探索了他完成该动作的最佳化问题,最后对把该动作发展成为连接性动作的可行性进行了研究。     

Whole-body and multi-joint kinematic control strategy variability during backward rotating dismounts from beam

The aim of this study was to develop insight into the whole-body and multi-joint kinematic control strategy variability associated with the execution of fundamental backward rotating dismounts from beam. Two-dimensional joint centre coordinate data were obtained for ten backward piked and backward tucked somersault dismount skills performed by four female gymnasts (N = 80 trials). Gymnast-specific and group variability in whole-body and multi-joint discrete kinematic measures were compared for the aerial and impact phase of backward piked and backward tucked skills. The backward tucked skill was executed using a more variable knee joint angular velocity at take-off (mean difference in standard deviation ± SD: -2.6 ± 1.0 rad · s(-1); P < 0.01) than the backward piked skill. The variability in the whole-body and multi-joint kinematic responses produced between the impact phases of each skill was gymnast-specific. The greater variability in the localized knee joint action at take-off was considered indicative of the diverse shape element demands and key performance outcomes of the two skills. Self-selected modulations to the multi-joint kinematic strategy used in the impact phase suggested customization of the joint loading adjustments in executing the fundamental dismount skills.     

中、外优秀体操运动员单杠成套动作比较研究

对九运会与第 35届世界体操锦标赛单杠决赛的成套动作进行了对比研究 ,结果表明 :中、外优秀运动员成套动作的起评分和最后得分无显著差异 ,而在飞行动作加分上有非常显著差异 ,中国运动员飞行动作的数量少、难度低 1个组别 ,且完成动作能力较差 ,下法落地的稳定性要继续提高     

Multidimensional joint coupling: a case study visualisation approach to movement coordination and variability

Abstract

A case study visualisation approach to examining the coordination and variability of multiple interacting segments is presented using a whole-body gymnastic skill as the task example. One elite male gymnast performed 10 trials of 10 longswings whilst three-dimensional locations of joint centres were tracked using a motion analysis system. Segment angles were used to define coupling between the arms and trunk, trunk and thighs and thighs and shanks. Rectified continuous relative phase profiles for each interacting couple for 80 longswings were produced. Graphical representations of coordination couplings are presented that include the traditional single coupling, followed by the relational dynamics of two couplings and finally three couplings simultaneously plotted. This method highlights the power of visualisation of movement dynamics and identifies properties of the global interacting segmental couplings that a more formal analysis may not reveal. Visualisation precedes and informs the appropriate qualitative and quantitative analysis of the dynamics.