Countermovement jump performance assessment using a wearable 3D inertial measurement unit

The aim of this study was to validate a wearable inertial measurement unit (IMU), containing a 3D accelerometer and gyroscope, for the estimation of countermovement jump height. The absolute vertical acceleration of the IMU positioned on the back of the participant at L5 level, compensated for trunk rotations, was used to obtain jump height by applying the equation of free-fall to the motion of the IMU. The methodology was tested on 28 participants performing five countermovement jumps each. A reference value for this quantity was obtained using stereophotogrammetry (35.4 cm, s = 4.9). Jump height scores obtained using the proposed methodology (35.9 cm, s = 5.5) presented no significant difference with respect to stereophotogrammetry (P = 0.61). A low bias of 0.6 cm confirmed the accuracy of the estimate, which also showed a high (r = 0.87) and significant (P < 0.0001) correlation with reference values. Furthermore, without compensating accelerations for trunk rotation, jump height was largely underestimated (P < 0.0001) (bias: -12.7 cm) and poorly associated (r = 0.31) with stereophotogrammetry. The results of this study show that the estimation of jump height using inertial sensors leads to accurate results when the measured accelerations are corrected for trunk rotations.     

Greater lower limb flexion in gymnastic landings is associated with reduced landing force: a repeated measures study

High impact forces during gymnastic landings are thought to contribute to the high rate of injuries. Lower limb joint flexion is currently limited within gymnastic rules, yet might be an avenue for reduced force absorption. This study investigated whether lower limb flexion during three gymnastic landings was related to force. Differences between landings were also explored. Twenty-one elite women's artistic gymnasts performed three common gymnastic techniques: drop landing (DL), front and back somersaults. Ankle, knee, and hip angles, and vertical ground reaction force [(vGRF) magnitude and time to peak], were measured using three-dimensional motion analysis and force platform. The DL had significantly smaller peak vGRF, greater time to peak vGRF and larger lower limb flexion ranges than landing from either somersault. Peak vGRF and time to peak vGRF were inversely related. Peak vGRF was significantly reduced in gymnasts who landed with greater hip flexion, and time to peak was significantly increased with increasing ankle, knee, and hip flexion. Increased range of lower limb flexion should be encouraged during gymnastic landings to increase time to peak vGRF and reduce high impact force. For this purpose, judging criteria limitations on lower limb flexion should be reconsidered.     

我国艺术体操个人运动员踹燕转体动作的应用及影响因素

通过对我国艺术体操个人运动员在成套中采用踹燕转体动作的现状和对各省市开展踹燕转体动作进行调查,分析我国艺术体操成年运动员学习和掌握踹燕转体难度动作的情况以及阻碍我国发展此类型难度动作的原因,以期为教练员和运动员的训练实践提供有益参考。     

世界体操冠军程菲少儿时期训练特点

程菲已成为闻名世界的优秀体操运动员,她在武汉体育学院从事过两年多的初中级体操训练。实践证明,重视思想教育,关心队员学习与生活,扎实抓好全面的、基础的训练内容是培养优秀体操运动员的成功之路。程菲少儿时期的训练特点可为少儿体操运动员的基础训练提供有益的启示。     

Performance of gymnastics skill benefits from an external focus of attention

The present study was designed to fill a gap in the literature on attentional focus and sports performance. Specifically, in contrast to most previous studies in which an external focus was directed at an implement, we used a gymnastics skill that did not involve the use of an implement. Furthermore, while most studies used only outcome measures of performance, we also assessed movement quality. Twelve-year-old gymnasts performed a maximum vertical jump with a 180-degree turn while airborne, with their hands crossing in front of their chest during the turn under three different focus conditions. Under the external focus condition, participants were asked to focus on the direction in which a tape marker, which was attached to their chest, was pointing after the turn. Under the internal focus condition, they were asked to focus on the direction in which their hands were pointing after the turn. Under the control condition, no focus instructions were given. The external focus condition resulted in both superior movement form and greater jump height than did the other two conditions, which produced comparable results. The present findings show that, similar to other tasks, the performance of form-based skills can be enhanced relatively easily by appropriate external focus instructions.     

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.     

女子举重运动员不同纵跳方式中生物力学参数与专项成绩的相关研究

通过采用5种不同的纵跳方式,对12名女子举重运动员髋、膝关节的角度、角速度等生物力学参数进行采集,所获数据和举重专项成绩进行相关分析.结果表明不同纵跳方式中的纵跳高度和专项成绩都有不同程度的相关.其中60cm下落跳中的生物力学参数和专项成绩相关因素最多,尤其是下落后的纵跳高度和弹性能利用率和专项成绩高度相关,相关程度在0.8左右水平.并且根据相关分析结果提出一种针对举重运动员的肌肉快速力量和离心肌力的训练方法,即适宜高度为60cm的跳深练习.     

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).     

世界优秀女子跳马运动员高难动作完成情况的对比分析——兼论2012年伦敦奥运会女子跳马竞争格局

通过文献资料调研、录像观察和数理统计法,对第29届奥运会、第41届世界体操锦标赛、第11届全国运动会和第42届世界体操锦标赛女子跳马单项决赛运动员跳马动作进行对比分析.结果表明,1)在动作类型上,国外运动员以踺子类、前手翻类为主,而我国运动员踺子类、前手翻类和侧手翻类均衡发展;2)中国运动员与国外运动员相比,在最高动作难度和动作质量上均稍差;3)2012年伦敦奥运会女子跳马项目中国运动员具有优势,但美国和俄罗斯运动员亦不容忽视,个人优势逐渐减弱,整体实力仍需提高.     

从第28届奥运会体操比赛看男子跳马的发展态势

采用调查访问、录像观察和文献资料调研等方法,对第2 8届奥运会体操比赛进入男子跳马单项决赛前8名运动员的比赛成绩、动作难度及完成情况进行了统计分析,并与第37届世界体操锦标赛跳马决赛运动员的有关数据做了比较研究。结果表明:跳马动作的高难度固然是运动员冲击金牌的前提,但落地稳定性却是夺冠的关键所在。     

Prevalence of a characteristic gene profile in high-level rhythmic gymnasts

Abstract

High-level physical performance in rhythmic gymnastics is influenced by numerous skills and anthropometric factors. In order to understand if genetic predisposition could play a role to define the elite rhythmic gymnast phenotype, we analysed the frequency of common polymorphisms linked to genes correlated with body mass (ADRB2 and FTO), explosive strength (ACTN3 and ACE), and joint mobility (COL5A1), in 42 gymnasts involved in National and International events, and in 42 control girls. Our results demonstrated that high-level rhythmic gymnasts constituted a genetically selected population showing higher frequency of: (a) ADRB2 and FTO alleles linked to low body mass index and low fat mass; (b) COL5A1 CT genotype linked to high joint mobility and to the occurrence of genu recurvatum, but also to a higher incidence of injuries. ACTN3 and ACE polymorphisms did not appear to be connected with the phenotype of high-level rhythmic gymnast. Based on these data, it can be assumed that these polymorphisms could positively affect the phenotype and performance of gymnasts.     

Performance characteristics of Parkour practitioners: Who are the traceurs?

Parkour is a modern physical activity that consists of using the environment, mostly urban, as a playground of obstacles. The aims of this study were (i) to investigate age, anthropometric and training characteristics of Parkour practitioners, called ‘traceurs’ and (ii) to assess jump performances and muscular characteristics of traceurs, compared to those of gymnasts and power athletes. The mean age of the population of traceurs studied (n?=?130) was 19.4?±?4.3 years, women represented 12.4% of the total field and mean training volume was 8.1?±?0.5?hours/week. Vertical and long jump performances were analysed on smaller samples of participants (four groups, n?=?15 per group); and eccentric (?90°?s^?1, ?30°?s^?1), concentric (30°?s^?1, 90°?s^?1) and isometric knee extensors torques were evaluated by means of an isokinetic dynamometer. Traceurs showed greater (P?P?P?P?相似文献   

Anthropometric and biomechanical field measures of floor and vault ability in 8 to 14 year old talent-selected gymnasts

The aim of this study was to identify the anthropometric and physical prerequisites for high difficulty floor tumbling and vaulting. Twenty 8-14 year old female talent-selected gymnasts performed handstand push-offs, and single and multiple jumps on a portable Kistler force plate. The force curves were analysed using Kistler and Excel software to obtain peak displacement, peak take-off force, and power The gymnasts were also assessed for sprinting, with and without vaulting, and standing broad jump performances. Video footage from the vault take-off was analysed using Video Expert II software to obtain the horizontal and vertical take-off velocities. Each gymnast's best vault starting score, three best floor tumbling skills, and anthropometric characteristics were recorded. Statistical analysis included one-way analysis of variance (ANOVA) to examine the effect of age (8-10 years, 11-12 years, 13-14 years) on the performance measures and linear regression analysis with performance start score for vault or best floor tumbling score as the outcome variable. The best regression model for indicating vaulting talent had, as predictor variables, resultant velocity at take-off from the board, squat jump power, and average power during the last five jumps in the continuous bent-leg jump series. The best regression model for indicating floor tumbling ability had, as predictor variables, age, vault running velocity, and reduced ground contact time in a handstand push-off.     

北京市男子体操队专项力量测评研究

为对吊环运动员专项力量的科学化训练提供理论依据,运用美国最新研制的CYBEX一6000型等动测力仪对北京市体操男队11名队员进行了肩关节的外展与内收、前屈与后伸及腰腹背屈伸肌力量的实验测试,对其各种力量素质发展水平做出分析与评价,并得出相应的优秀男子体操运动员各种力量素质的临界值。同时对11名队员进行了专项教学指标的测试,把教学指标参数分别与其实验测试的各种力量参数及运动员的比赛成绩进行了相关性分析,并得出优秀男子体操运动员有关专项教学指标的临界值。     

Validity of vertical jump measurement devices

Vertical jump height is thought to provide a valuable index of muscular power, which is an important factor in sports performance and for assessing the mobility and functional capacity of injured or aged individuals. The purpose of the present study was to investigate the criterion validity of four popular devices for measuring vertical jump height. A belt mat, contact mat, portable force plate, and Vertec were compared to a criterion device, a laboratory force plate. Forty participants performed three maximal countermovement jumps on each device in a counterbalanced order, using block randomization. The criterion device presented the highest mean value (50.3 cm). The portable force plate and belt mat devices recorded similar jump height values to the criterion device (within 1 cm). The contact mat and Vertec devices recorded significantly lower values than the criterion device (P < 0.001). The mean difference ± limits of agreement were: belt mat -0.1 ± 5.5 cm, contact mat -11.7 ± 6.4 cm, portable force plate -0.8 ± 3.9 cm, and Vertec -2.4 ± 6.6 cm. In conclusion, the portable force plate and belt mat devices provided valid measures of vertical jump height, whereas the Vertec and contact mat devices did not.     

我国高水平艺术体操运动员竞赛焦虑水平对比赛稳定性的影响

通过问卷调查和个案分析 ,研究艺术体操运动员焦虑水平对比赛稳定性的影响。结论认为 ,运动员焦虑水平对比赛的稳定性有不同程度的影响 ,低认知焦虑和高位状态自信心有助于比赛稳定性提高 ;运动员参加不同层次比赛 ,焦虑水平有显著差异 ;运动员自信心较认知焦虑和躯体焦虑对比赛有更大影响     

Gymnastic Judges Benefit From Their Own Motor Experience as Gymnasts

Gymnastic judges have the difficult task of evaluating highly complex skills. My purpose in the current study was to examine evidence that judges use their sensorimotor experiences to enhance their perceptual judgments. In a video test, 58 judges rated 31 gymnasts performing a balance beam skill. I compared decision quality between judges who could perform the skill themselves on the balance beam (specific motor experience = SME) and those who could not. Those with SME showed better performance than those without SME. These data suggest that judges use their personal experiences as information to accurately assess complex gymnastic     

Gaze Behavior of Gymnastics Judges: Where Do Experienced Judges and Gymnasts Look While Judging?

Gymnastics judges and former gymnasts have been shown to be quite accurate in detecting errors and accurately judging performance. Purpose: The purpose of the current study was to examine if this superior judging performance is reflected in judges’ gaze behavior. Method: Thirty-five judges were asked to judge 21 gymnasts who performed a skill on the vault in a video-based test. Classifying 1 sample on 2 different criteria, judging performance and gaze behavior were compared between judges with a higher license level and judges with a lower license level and between judges who were able to perform the skill (specific motor experience [SME]) and those who were not. Results: The results revealed better judging performance among judges with a higher license level compared with judges with a lower license level and more fixations on the gymnast during the whole skill and the landing phase, specifically on the head and arms of the gymnast. Specific motor experience did not result in any differences in judging performance; however, judges with SME showed similar gaze patterns to those of judges with a high license level, with 1 difference in their increased focus on the gymnasts’ feet. Conclusion: Superior judging performance seems to be reflected in a specific gaze behavior. This gaze behavior appears to partly stem from judges’ own sensorimotor experiences for this skill and reflects the gymnasts’ perspective onto the skill.     

Acute whole-body vibration does not affect static jump performance

Abstract

Currently, whole-body vibration is being used to promote enhanced performance. Many coaches and athletes believe that it can acutely enhance explosive performance and power output. However, the scientific literature is unclear as to whether this enhancement occurs. The purpose of this study was to examine the acute effects of whole-body vibration on static jump performance, including jump height, peak force, rate of force development, and peak power. Fourteen recreationally active individuals (5 females, 9 males) participated in three separate randomized treatment sessions. Treatment 1 consisted of no vibration while treatment 2 and treatment 3 incorporated whole-body vibration. The whole-body vibration protocol consisted of three 30-s bouts of vibration performed at 30 Hz and low amplitude (~3 mm) with a 30-s rest between bouts. Treatment 1 was identical in duration to both treatments 2 and 3, but did not contain any vibration. Five minutes after each treatment, the participants performed the static jump protocols. Two (data averaged) non-weighted static jumps and two 20 kg weighted jumps were performed. Treatments 1 vs. 2, 1 vs. 3, and 2 vs. 3 were calculated for each variable at both 0 kg and 20 kg. Jump height, peak force, rate of force development, and peak power were analysed using a one-way analysis of variance with repeated measures. The intra-class correlations comparing the two trials of each jump for each of the three treatments were ≥0.92. Compared with the no-vibration condition, jump height showed a non-significant increase as a result of whole-body vibration for both unweighted and weighted jumps; peak force, rate of force development, and peak power were not statistically different. The results indicate that whole-body vibration has no effect on jump height, peak force, rate of force development or peak power during static jumping.     

我国竞技体操50年发展动态的量化分析

以历届全运会竞技体操比赛成绩和近 4届奥运会体操比赛我国进入前 8名运动员的成绩及其所代表的单位为主要研究对象 ,从量化的角度分析我国竞技体操 5 0年发展的格局和地理分布特征、与经济发展的关系和各代表队的综合实力 ,并对今后我国竞技体操的发展提出相应建议