再论赛艇动力学--对FISA《赛艇教练员培训教程》动力学理论的商榷

对黄胜初于2000年建立的双动力赛艇动力学方程进行矢量推导,结果显示,在操桨过程中人体质心的移动产生无击水动力。据此,认为国际赛艇联合会(FISA)赛艇教练员培训手册(2002年版)中,单动力赛艇动力模型衍生出的三点错误之处。研究认为,国内生物力学界和赛艇界对赛艇动力学及其在训练中的应用存在认识上的误区。应注重回桨技术的研究和训练,降低1桨中拉推桨时间比,提高1桨的划桨效率。     

赛艇动力学及流体动力性能和快速性能研究

对赛艇划桨过程中回桨阶段出现第二个加速度峰值的动力源进行了分析,提出运动员在回桨过程中,人体重心从船头向船尾移动产生冲力,从而使船艇加速。并据此提出了包括拉桨动力和人体重心移动产生冲力两个动力源的赛艇动力学方程。此外,对提高赛艇技术的途径和赛艇桨叶及船艇的流体动力性能和快速性能进行了分析和论述,为提高赛艇训练的科学化水平提供了依据。     

中国精英女子赛艇运动员划桨技术特点分析

目的：以国家队和赛艇优势省队运动员为测试对象，总结分析我国精英女子赛艇运动员的划桨技术特点。方法：27名运动员参与本研究，利用"BioRow Tel"系统测试五种桨频（20、24、28、32、36桨/分）下的划桨技术，测试参数包括划桨节奏、桨叶轨迹、桨力特征等。结果：拉桨时间百分比随桨频的提高显著提高；入水角、出水角和划幅在中低桨频下非常稳定，但在接近比赛桨频时显著下降；抓水打滑和出水打滑均随桨频的增加而显著增加；与桨力相关的参数对桨频的变化相对不敏感。结论：我国运动员较为注重桨叶入水和拉桨前段，表现出的技术较好，而在拉桨后段特别是桨叶出水阶段暴露出的问题比较大；临近比赛桨频时的技术同中低桨频时相比存在比较明显的下降。训练中要解决好拉桨后段和桨叶出水的问题，并注重提高运动员在比赛桨频时的划桨技术。     

湖北省男子公开级赛艇运动员划桨动作技术分析

选取湖北赛艇队男子公开级3名运动员作为研究对象,利用奥地利WEBA sport公司的Rower Expert Light 赛艇实船测试系统对三名男子公开级赛艇选手进行单人双桨实船划桨测试.测试发现:随着桨频的增加,拉桨时间、推桨时间、单次划桨时间以及推拉比都在减小,而推拉比的减少意味着推桨所需时间减少得更快.拉桨的力量并没有明显增加,被测试的3名运动员都是左手拉力大于右手拉力.拉桨最大力产生时桨叶的位置会逐渐靠近运动员身后,相应的最大力产生的时间会提前.运动员左右手拉力的不平衡以及最大力产生的位置不一致都会影响到赛艇的航向.转桨角的变化幅度不大,但在四种桨频下,3名运动员的入水角都大于出水角.3名运动员的左转桨角比右转桨角大,意味着3名运动员左手桨叶的划幅比右桨大.     

赛艇划桨技术初论

赛艇划桨动作是由提桨(入水)——拉桨(划水)一按桨(出水)——推桨(回桨)四个部份组成的,这也称为一个划桨周期。其中,拉桨是桨叶在水中划水作功的过程,它产生推功赛艇前进的动力,其余三个动作(以后简称推桨)则是组成一个划桨周期必不可少的过渡动作。在每个周期中赛艇前进的速度并不是均匀的。图一所示赛艇划桨周期的速度曲线图,是以专用的电子仪器于一九八三年十二     

基于赛艇实船测试系统对我国优秀男子轻量级赛艇运动员划桨技术的研究

利用赛艇实船测试系统对男子轻量级赛艇选手进行单人双桨实船划桨测试.测试发现:随着桨频的增加,拉桨与推桨速度同时增加,但推桨速度增长得更快,转桨角度和拉桨幅度呈减小趋势,拉桨力略呈下降趋势;最大正加速度和负加速度的绝对值都呈增加趋势,但负加速度的持续时间和其在整个划桨周期中所占的时间比例在减少;运动员左右手拉力的不平衡以及最大力产生的位置不一致的现象比较普遍,这对于航向的保持有较大影响.     

我国优秀赛艇运动员桨力- 时间曲线特征

赛艇运动中拉桨阶段的桨力曲线反映了运动员的发力特征，是专项竞技能力诊断的重要途径。根据国家队的测试实例，对不同艇种、不同桨位的桨力曲线特征进行归纳分析总结，对赛艇项目进行系列测试（桨频：35桨/min），结合专项认为专项技术较好的多人艇运动员大多采用A型；双人单桨项目中．领桨手倾向于采用A型桨力-时间曲线，一号位桨手倾向于采用B型桨力-时间曲线。不同桨频下的桨力-时间曲线特征可作为训练效果的评估依据，低桨频训练必须保持合理的拉桨速度和拉桨力量。     

基于桨力测量分析的皮艇专项竞技能力评价指标体系构建

在总结国内外研究工作的基础上提出了基于实测桨力和船体加速度信息的皮艇专项竞技能力评价指标体系的建立方法,采用因子分析法提取出了桨频、绝对船速差、船体颠簸和摇晃加速度、拉桨平均桨力、最大桨力衰减、桨力平坦度和拉桨节奏等11项代表性指标构成静水皮艇专项竞技能力评价指标体系,简明有效地反映了运动员的身体素质、专项力量素质、动力保护和拉桨控船技术等专项竞技能力。     

国际大赛中男女皮艇运动员划桨节奏的比较研究

采用现场摄影法,比较世界杯赛中男女皮艇运动员的桨频和划桨节奏。结果显示：男桨手左右两侧的桨频比较和女桨手左右两侧的桨频比较均无差异;大赛中实际应用时两侧计算桨频无差异。动作节奏上．男桨手左右两侧和女桨手右侧无差异;只有女桨手左侧与前三者有差异,可能是女子两侧专项素质发展及技术完善的同步性不如男子。男桨手提高桨频可能靠减少回桨时间而女桨手靠减少拉桨时间获得;高桨频时男桨手容易保持水中效果而女桨手容易丢失效果。     

对中外优秀女子单人皮艇运动员桨频及划桨节奏的分析

采用Simi Motion运动分析系统,对国内外优秀女子单人皮艇运动员一个完整划桨周期技术进行分析.结果表明:中外优秀运动员左侧桨频及各个阶段的时间比例均没有显著性差异(P>0.05),右侧动力阶段时间比例存在非常显著性差异(P<0.01);国内优秀运动员左右两侧划桨的对称性和一致性要优于国外优秀运动员;优秀运动员菜频的提高有提高拉桨时间比例,相应缩短回桨时间比例的趋势.     

番子拳的内容与分类的整理研究

本文对番子拳按基础、功力、技击、套路四部分进行分类整理，并就番子拳的训练进行研讨。     

Time-out! How psychological momentum builds up and breaks down in table tennis

ABSTRACT

The current study examined the development of psychological momentum (PM) in table tennis and the effect of a time-out. Eighty table tennis players were exposed to an audiovisual scenario, in which they either came back from 1–7 to 7–7 in an all-decisive game (positive momentum), or in which the opponent came back from 7–1 to 7–7 (negative momentum). Furthermore, at the score of 7–7 a time-out was called. One group of participants received no specific instructions during the time-out, whereas the other group received task (mastery-approach – MAp) instructions. Overall, PM perceptions increased for participants in the positive momentum condition, but decreased rapidly for participants in the negative momentum condition. In addition, the time-out led to a loss of PM in the positive momentum condition, but to a recovery of PM in the negative momentum condition. The instructions during the time-out did not make a significant difference. Together, these results suggest that scoring patterns in a table tennis game significantly affect the PM of players. Furthermore, a player or coach could benefit from calling a time-out in a negative momentum situation, as this provides an opportunity to psychologically recover.     

关于改革我国排球教材技、战术分类体系的研究

我国现有排球教材技、战术分类体系过于强调第3次击球环节的进攻与防守,而忽视第1次击球与过渡环节的进攻与防守;新的排球运动技、战术体系分类方法是根据排球运动的基本规律,首次击球、过渡击球、最后击球3个环节进行分类。     

Total kinetic energy production of body segments is different between racing and training paces in elite Olympic rowers

Total kinetic energy (TKE) was calculated for 28 Canadian national team Olympic rowers during training on water, comparing low-stroke rates (18–22 stroke/min) and high-stroke rates (32–40 stroke/min), using video analysis. Stroke duration was normalized to 100%, beginning and ending at the “catches”, with the drive phase occurring first and recovery second. Two discrete points were identified during the stroke, both occurring when the fingers had the same horizontal position as the ankles (i.e. mid-drive and mid-recovery). The ratios of recovery-to-drive TKE at these points for the entire body at low and high-stroke rates were 0.36 ± 0.34 and 1.26 ± 0.54 respectively. Significant differences were found for the lower leg, upper arm and forearm segments, and within the female groups. Low-stroke rate is a typical training pace and high-stroke rate is analogous to a race pace. This study demonstrates that TKE production during recovery in a race was not replicated during training. While training at low-stroke rates is vital for technique refinement, this study stresses the importance of training appropriately for the energy expenditure during high-stroke rate recovery. This is commonly overlooked by coaches and athletes.     

Effect of endurance training on blood lactate clearance after maximal exercise.

The aim of this study was to measure serial changes in the rate of blood lactate clearance (gamma2) in response to sequential periods of training and detraining in four male triathletes aged 22-44 years. There were two major phases of training and taper, each lasting 4-5 weeks (training 1 = 5 weeks, taper 1 = 2 weeks, training 2 = 4 weeks and taper 2 = 2 weeks), in preparation for a triathlon competition. The training stimulus absorbed by each subject was carefully quantified from the duration and intensity of the training exercise. A serial weekly measure of each trainee's physical response to training was evaluated as the peak power, termed a 'criterion performance', developed by a subject during a 30 W x min(-1) ramp cycle ergometer test to exhaustion each week. During 30 min of recovery after this test, 13 samples of venous blood were drawn sequentially from a subject to measure the blood lactate recovery curve. The rate constant of blood lactate clearance was estimated by a non-linear least-squares regression technique. In addition, the concurrent time to peak lactate concentration and the peak lactate concentration were also estimated to help define changing lactate kinetics. The criterion performance generally declined throughout each period of incremental training and improved during each taper period, rising iteratively in this way to be clearly above baseline by the end of the second taper. The blood lactate clearance rate increased transiently in early training before declining from the middle of the first training period to the middle of the first taper; thereafter, gamma2 increased above baseline in each trainee throughout the remaining first taper and the major portion of the second training period, decreasing only in the final criterion performance test. The time to peak lactate declined from baseline throughout all phases of training and taper. Peak blood lactate increased in all subjects to the end of the first taper before declining by the end of the second training period, rising again to baseline levels during the second taper. The change in gamma2 was examined relative to the work rate achieved in cycle ergometry above an initial baseline score (deltaCP) and against concurrent peak blood lactate. There was a clear upward shift in gamma2 above baseline throughout the first and second training and taper in two subjects; this was less clear in the remaining two subjects, each of whom had a lower deltaCP. We conclude that this indicates improved lactate clearance, manifest by the change in gamma2 induced by endurance training.     

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.     

女子划艇十三运会赛前12周训练负荷结构特征分析

运用文献资料法、专家访谈法、跟踪测试法、数理统计法,对江西女子划艇队夺冠成员在2017年天津全运赛前12周训练负荷结构特征进行分析,为总结高龄运动员的训练模式特征提供实证依据。结论:女划运动员在第一阶段以恢复、提升运动员的基础体能为重点;第二阶段以巩固、提升有氧能力和强化水上专项能力进行训练实施。训练的总量趋势大体呈先增量后减量;越临近比赛,水上训练量逐步增加,陆上训练量逐渐减少。江西女划队以有氧训练为主,有氧训练所占的比列最高;水上抗阻训练比例和水上速度训练比例相当;SKM训练类型的训练比例最低,模拟比赛训练的比例仅高于SKM训练类型。陆上机能训练中大力量训练比例最高;力量耐力次之;陆上有氧训练再次之,其中,自身负重和核心训练是调节性训练,比例较低。此外,江西女划队特别注重运动员的机能恢复训练。     

冰雪运动员赛后心理变化特点与恢复手段

运动员赛后心理恢复对运动员心理优势的完善和形成,对推进冰雪运动员竞赛和训练一体化进程具有重要的作用。认为冰雪运动员赛后心理具有动作技能动力定型负向变化、竞赛动机水平变化、自信心正负变化、情绪变化幅度较大等特点,提出积极采用运动员动作认知结构的恢复、增强运动员自信心、修复运动员比赛动机、调整运动员紧张情绪等手段及时进行赛后心理恢复,以促进运动员心理优势的完善和形成,为冰雪运动员的科学训练提供相应的理论支持。     

The efficacy of video feedback for learning the golf swing

This study was designed to examine the efficacy of video instruction relative to that of verbal and self-guided instruction. Before training, 30 golfers were assigned at random to one of three groups: video, verbal or selfguided instruction. Video instruction was defined as a practice session in which the teacher was aided by the use of video. Verbal instruction was defined as practising with the teacher providing verbal feedback. Self-guided practice was defined as practising without the aid of a teacher. The participants had a pre-test, four 90 min practice sessions, an immediate post-test and a 2 week delayed post-test. During the pre-test and post-tests, all participants were required to strike 15 golf balls, with a 7-iron, from an artificial turf mat for distance and accuracy. The results showed that all groups were equal on the pre-test. On the first post-test, the two instruction groups performed worse than the self-guided group. However, on the second post-test, the two instruction groups performed better than the self-guided group, with the video group performing best. We interpret these results to mean that video analysis is an effective means of practice, but that the positive effects may take some time to develop.