健美操新规则下集体类项目托举动作特征的研究

文章运用文献资料法、录像分析法、专家访谈法、数理统计法等研究方法,对竞技健美操新规则下托举动作的创编、难度、动作技术的完成进行分析研究,研究得出：成套动作中托举在不同水平空间的不同形态对托举动作价值有重要影响;成套动作中托举动作的创新性、尖子复杂的身体形态、多样的空间变化成为托举难度价值评分的主要内容。托举动作水平差异较大,个别国家在托举创新和动作技术类型上有突破,但一些国家普遍还停留在上个周期的托举评判规则中,使托举在成套动作中的动作形态过于单一,空间变化少,导致托举价值不高。如何体现托举难度在成套动作中的价值成为新的研究方向。     

竞技健美操六人项目托举编排及设计研究

通过观察第10届、第11届2个不同规则周期(2005—2008与2009—2012)的世界健美操锦标赛现场录像,针对六人项目中的托举编排与设计的时间特征、动作类型、组合形式、运动空间、姿态变化等一些较客观、可量化的指标进行统计分析与比较,探讨了托举编排和动作设计的一般规律和发展趋势。研究认为,托举是竞技健美操六人项目艺术评判的重要内容之一,竞赛规则的变化发展不断为托举动作的创新设计提供了更广的发展空间。现阶段以托举静止造型作为开场的运用有所减少,以托举静止造型作为结束仍然较为普遍;托举在成套动作中的总时间有所增加;动力性托举以及动力性与静力性结合的托举动作的运用较多,翻转动作以及有接触抛接动作运用非常普遍;底座的人员组合形式多变;尖子的重心起伏与动作姿态变化频繁。然而,底座的动作类型与施力方式、空间利用、动作姿态变化等方面表现不足,尖子的人数与组合形式较局限。     

2009年新周期国际健美操规则导向下我国竞技健美操成套动作难度与编排创新发展研究

对2009年国际健美操评分规则全面解读,认为规则变化有:(1)艺术裁判评分内容和分值重组;(2)难度动作总数增多,价值提高;(3)难度技术完成完美化;(4)托举动作允许采用违例动作.时今后我国健美操的发展提出重视成套动作编排的创新;提高运动员身体素质和能力;注重难度组合和操化组合的多样性;重视音乐选择和运用等对策.     

第9届健美操世锦赛中国队与冠军队三人操项目编排对比分析

对第9届健美操世界锦标赛中国队与冠军队三人操项目的编排对比分析表明：中国选手在难度动作分布的均衡性和难度级别在成套动作中出现的顺序不够合理,难度动作的级别也较低;动力性配合动作的编排较简单,配合时间短,没有空间体位的变化,缺乏亮点;托举动作的类型单一,缺乏创造性。     

竞技健美操混双项目托举动作的分析

采用录像观察法对近几年国内外大型比赛中混双项目的托举动作进行了统计分析,结果表明:在竞技健美操混双项目托举动作的编排上,不仅要具有一定的创新性、新颖性和复杂性,而且还要体现不同空间和不同面的结合,整个托举动作要流畅、美观,给裁判留下深刻印象,给观众以视觉上的冲击与享受。同时,托举动作又是男女队员感情沟通的桥梁,展示了托举者的力量和稳定性,也展示了被托举者的平衡性和协调性。在今后的训练中,应着重提高我国混双项目托举动作的艺术性。     

艺术体操新旧规则的对比研究

通过对2001、2003和2005年版艺术体操规则的对比研究,分析新规则的主要变化特点,结果表明:1)新规则对运动员完成动作质量提出了更高的要求,动作出现失误,扣分力度将增大;2)提高了艺术价值中的特殊艺术性加分权重;3)难度级别不断增加;4)突出各项目器械的身体动作特点,对运动员综合素质提出了更高的要求;5)重视动作的审美价值,强调成套动作的竞技性和观赏性。     

应用功能性体能训练方法提高优秀花样游泳运动员爆发力的实证研究

随着近年来花样游泳比赛动作难度的不断增加,对运动员爆发力的要求也不断提高。本研究在距离全国花样游泳冠军赛6周时,为我国9名优秀花样游泳运动员制定赛前功能性体能训练计划,帮助运动员提高比赛所需要的爆发力。通过训练前后的爆发力测试,发现运动员的CMJ纵跳高度、坐瑞士球托举动作的最大爆发力、快速托举模拟动作的最大爆发力、连续模拟划水动作平均功率测试数据均有非常显著性增长（P〈0．01）。     

第15届亚运会花样游泳比赛中、日两国实力对比分析

对第15届亚运会中国、日本两队花样游泳比赛情况进行分析结果表明,中国队在亚运会上获胜的主要原因是双人和集体技术自选必做动作同步的完成情况比日本队出色;双人和集体自由自选同步情况和完成质量稍占优势;集体自由自选单个动作难度、创新动作难度及难度组合总体上超越日本队;双人和集体自由自选项目的音乐选择和编排设计比较成功,艺术印象分是战胜日本队的关键因素。存在问题是技术自选和自由自选动作的水位质量不如日本队;自由自选占优势的技术动作中难度价值不如日本队,如转体和旋转的最高周数及出现次数、双手在上踩水时间、双人项目托举的难度、全套出现星级难度的次数等。建议中国队要提高必做动作和各类技术动作的水位质量;在技术自选的编排中充分考虑附加内容的难度价值;双人和集体自由自选要尽快攻克技术弱项,提高难度动作的全面性,总体难度还须再上台阶。     

广东省花样游泳托举“二托一托一”准备动作技术分析

采用录像分析、数理统计、逻辑分析等研究方法,对广东省花样游泳托举二托一托一准备动作进行研究,选取广东省3名健将级的花样游泳运动员,分析其托举准备动作各参数变化规律,找出其技术动作所存在的问题,为提高花样游泳托举技术水平提供参考。     

只有创新才有希望——中国花样游泳队现状之我见

在近十年中,世界花样游泳的格局发生了较大的变化,俄罗斯、日本、美国等国家引领世界潮流。相比之下,我国的花样游泳水平目前正处于一种较为尴尬的局面。虽然在世界大赛中能够进入最后的决赛,但最终的名次总是徘徊于第六名、第七名之间。因此,要赶超世界花样游泳强国,除了要加强科学选材和创新有效的训练方法之外,还必须加强对花样游泳强国技术动作特点的研究。就拿雅典奥运会冠军俄罗斯队来讲,在决赛中,全队托举动作虽然只有三次,但其中两次难度相当大,具有较高的冒险性和创新性,而中国队的托举相对较为保守和平淡。其次,俄罗斯队全队的队…     

第9届世界健美操锦标赛6人操决赛托举动作分析

采用文献资料法、录像观察法和对比分析法，对2006年第9届世界健美操锦标赛6人操决赛前8名队伍的托举动作进行分析，找出各队伍托举动作的相同与独特之处，以期对从事竞技健美操6人操托举动作的工作者提供参考。     

Control of propulsion and body lift during the first two stances of sprint running: a simulation study

The aim of this study was to relate the contribution of lower limb joint moments and individual muscle forces to the body centre of mass (COM) vertical and horizontal acceleration during the initial two steps of sprint running. Start performance of seven well-trained sprinters was recorded using an optoelectronic motion analysis system and two force plates. Participant-specific torque-driven and muscle-driven simulations were conducted in OpenSim to quantify, respectively, the contributions of the individual joints and muscles to body propulsion and lift. The ankle is the major contributor to both actions during the first two stances, with an even larger contribution in the second compared to the first stance. Biarticular gastrocnemius is the main muscle contributor to propulsion in the second stance. The contribution of the hip and knee depends highly on the position of the athlete: During the first stance, where the athlete runs in a forward bending position, the knee contributes primarily to body lift and the hip contributes to propulsion and body lift. In conclusion, a small increase in ankle power generation seems to affect the body COM acceleration, whereas increases in hip and knee power generation tend to affect acceleration less.     

Reliability of the Trunk Lift in High School Boys and Girls

The purpose of this study was to examine the reliability of the trunk lift test. Eighty eight high school boys and girls performed two trials of the trunk lift test as described in the FITNESSGRAM manual (Cooper Institute for Aerobics Research, 1992) on each of 2 days. Intraclass correlation coefficients were used to examine norm-referenced reliability, whereas P and modified kappa (κ_m) were used to examine criterion-referenced reliability. Additionally, a goniometer was used to examine the relationship between the trunk lift test and trunk range of motion. Reliability ranged from R = .93 to .98 with estimated reliability of R = .90 for boys and R = .85 for girls for a single trial test. Using 9 inches as the cutoff score, P was .93 with κ_m = .86 for boys, whereas for girls both P and κ_m were 1.0. Specifically, 93% of boys and 100% of girls passed the trunk lift test on both days. The correlation between trunk lift scores and goniometer scores was r = .70 for boys and r = .68 for girls. These results suggest that the trunk lift test is a simple and highly reliable test. However, the concurrent validity of the trunk lift test and the validity of the cutoff score used for this test need to be determined. Finally, the relationship between low back pain and trunk lift scores needs to be examined.     

集体花球啦啦操成套动作编排研究——以广西第12届学生运动会前6名队伍为例

运用文献资料、录像观察、对比分析、数理统计等方法,对广西第12届学生运动会集体花球啦啦操前6名成套动作编排进行研究,力图寻找比赛制胜因素,为今后参赛队伍取得优异成绩提供理论参考。结果表明:在音乐;技术动作;托举配合;队形变化以及服装道具的编排上都会对比赛成绩造成影响,只有把握这5个方面的编排,才能够为队伍制胜的取得有利条件。     

Patterns of barbell acceleration during the snatch in weightlifting competition

The purpose of this study was to determine the association between weightlifting performance and vertical barbell acceleration patterns. Barbell kinematic time-series data were tracked from 18 snatches from six weightlifters during a regional weightlifting competition. These data were used to calculate vertical barbell accelerations. Time-series data were normalised to 100% of lift phase, defined as the time interval between barbell lift-off and maximum height of the barbell during each snatch lift. The time-series data were then entered into a pattern recognition algorithm that extracted principal patterns and calculated principal pattern scores. Body mass-normalised lift weight, which was used to quantify weightlifting performance, was significantly correlated (r = 0.673; P = 0.033) with a pattern that captured a difference in peak vertical barbell acceleration between the transition and the second pull phase. This correlation indicated that barbell acceleration profiles of higher weight snatch lifts were characterised by smaller decreases in acceleration during the second knee bend and smaller peak acceleration during the second pull phase. Weightlifting coaches and sports scientist should monitor and track vertical acceleration of the barbell, with focus on acceleration profiles that limit (1) deceleration during the transition phase between the first and second pull and (2) peak acceleration during the second pull phase of the snatch.     

Biomechanics of the Snatch Technique of Highly Skilled and Skilled Weightlifters

Abstract

The lifting techniques of 10 world-class weightlifters were compared to those of 26 skilled collegiate weightlifters while performing the first portion of the snatch, from the lift-off of the barbell to the catch of the barbell overhead with the body in a squatting position. Cinematography was used to measure the joint angles, position of the center of gravity of the body, and the position of the barbell. Results indicated that the world-class weightlifters raised the barbell to a relatively lower height, assumed more flexed positions at the hips and knees with a smaller angle between the shank and floor during certain stages of the lift, and lowered their bodies more rapidly during the squatting portion of the lift than the collegiate weightlifters.     

Experimental determination of baseball spin and lift

The aim of this study was to develop a new method for the determination of lift on spinning baseballs. Inertial trajectories of (a) ball surface markers during the first metre of flight and (b) the centre of mass trajectory near home-plate were measured in a pitch using high-speed video. A theoretical model was developed, incorporating aerodynamic Magnus-Robins lift, drag and cross forces, which predicts the centre of mass and marker trajectories. Parameters including initial conditions and aerodynamic coefficients were estimated iteratively by minimizing the error between predicted and measured trajectories. We compare the resulting lift coefficients and spin parameter values with those of previous studies. Lift on four-seam pitches can be as much as three times that of two-seam pitches, although this disparity is reduced for spin parameters greater than 0.4.     

Experimental determination of baseball spin and lift

The aim of this study was to develop a new method for the determination of lift on spinning baseballs. Inertial trajectories of (a) ball surface markers during the first metre of flight and (b) the centre of mass trajectory near home-plate were measured in a pitch using high-speed video. A theoretical model was developed, incorporating aerodynamic Magnus-Robins lift, drag and cross forces, which predicts the centre of mass and marker trajectories. Parameters including initial conditions and aerodynamic coefficients were estimated iteratively by minimizing the error between predicted and measured trajectories. We compare the resulting lift coefficients and spin parameter values with those of previous studies. Lift on four-seam pitches can be as much as three times that of two-seam pitches, although this disparity is reduced for spin parameters greater than 0.4.     

Measurements of drag and lift on tennis balls in flight

Measurements are presented of drag and lift on new tennis balls in flight. Two video cameras were used to measure the velocity and height of the balls at two positions separated horizontally by 6.4 m. The balls were fired from a ball launcher at speeds between 15 and 30 m/s and with topspin or backspin at rates up to 2,500 rpm. Significant shot-to-shot variations were found in both the drag and lift coefficients. The average drag coefficient was 0.507 ± 0.024, independent of ball speed or spin, and lower than the value usually observed in wind tunnel experiments. The lift coefficient increased with ball spin, on average, but significant lift was observed even at very low spin. The latter effect can be attributed to a side force arising from asymmetries in the ball surface, analogous to the side force responsible for the erratic path of a knuckleball in baseball.     

Factors determining the spin axis of a pitched fastball in baseball

In this study, we wished to investigate the factors that determine the direction of the spin axis of a pitched baseball. Nineteen male baseball pitchers were recruited to pitch fastballs. The pitching motion was recorded with a three-dimensional motion analysis system (1000?Hz), and the orientations of the hand segment in a global coordinate system were calculated using Euler rotation angles. Reflective markers were attached to the ball, and the direction of the spin axis was calculated on the basis of their positional changes. The spin axis directions were significantly correlated with the orientations of the hand just before ball release. The ball is released from the fingertip and rotates on a plane that is formed by the palm and fingers; the spin axis of the ball is parallel to this plane. The lift force of the pitched baseball is largest when the angular and translational velocity vectors are mutually perpendicular. Furthermore, to increase the lift forces for the fastballs, the palm must face home plate.