Knowledge of bout duration influences pacing strategies during small-sided games     

John Andrew Sampson  Hugh Head Kelsham Fullagar  Tim Gabbett 《Journal of sports sciences》2015,33(1):85-98

This investigation examines pacing during intermittent team sports. Sixteen junior Rugby League players participated in eight different small-sided offside touch games. All games were 24 min, but bout durations differed in continuous (1 × 24 min) or repeated (2 × 12, 3 × 8, 4 × 6, 6 × 4, 8 × 3, 12 × 2 or 24 × 1 min) formats. Repeat bouts were interspersed by 2 min of passive rest, and participants were informed of the bout duration immediately prior to the game. Heart rates, ratings of perceived exertion and data gathered from global positioning system devices were used to investigate the pacing strategies employed within each game. No significant (P > 0.05) between-game differences were observed in total distance; however, during the 1-min bouts, high-speed movement was significantly (P < 0.05) increased, during the first and second quarters of the 24 × 1-min game compared to all other formats (effect size range: 0.75 ± 0.61–1.38 ± 0.47). Furthermore, the rate of decline in high-speed movement over-time was greatest during the 24 × 1-min game with large differences observed between the first and third quarters (effect size: 0.90 ± 0.58). Greater moderate-speed (effect size range: 0.62 ± 0.63–1.56 ± 0.40) and less low-speed (effect size range: 0.69 ± 0.62–1.54 ± 0.40) distances were also observed during the 1-min bouts, yet heart rates were higher during the continuous 1 × 24-min game. Pacing strategies during intermittent activities are influenced by the number and duration of exercise bouts. Practitioners should consider within-game bout durations when prescribing game-based activities to improve aerobic capacity.  相似文献   

圆管分层两相流问题的解析方法     

卢天祥  张劲柏 《鸡西大学学报》2015,(1):61-63,74

管道输运工程中经常遇到两相流问题,因此需要预测对流体施加的压力大小以指导运输。拟对圆直管道分层两相流-层流模型做研究,用解析方法计算出圆管任一截面处流体的速度分布,并验证两层流体交界面处的摩擦力与其平均速度差值呈近似线性关系的结论。以此为基础,可以通过计算截面速度分布得到流体与管壁的摩擦力,通过输运流体所需达到的速度得到分界面处摩擦力,最终反推出运输流体所需要施加的压力差大小。  相似文献   

行人最大速度对行人流影响的研究     

刘祥树  陆安山 《钦州学院学报》2011,26(3):43-47

应用改进的格子气模型(即将行人的最大速度扩展到大于1)研究行人的最大速度对过道中单向和双向行人流的影响。模拟结果显示:最大速度为5时所对应基本图的临界密度跟实验值比较符合,说明该扩展是必要的;在一定范围内随着行人最大速度的增大道路的整体通行能力增强同时临界密度减小;双向行人流的时空斑图显示行人最大速度的增大加快了拥堵的形成过程(即缩短了行人从局部拥堵演化为完全拥堵的时间)。  相似文献   

初中生基于速度类运动处方体能素质干预实验研究     

杜晓兵 《体育科技》2014,35(4):127-129

通过速度类项目50米跑课外教学实验,施以不同的教学方法,观察学生速度类体能素质经运动处方干预后的变情况,并运用方差分析对所得实验数据进行统计分析.结果显示：采用运动处方的方式干预初中生的速度类体能素质发展效果明显好于一般的教学方式.  相似文献   

Circadian rhythm effect on physical tennis performance in trained male players     

Álvaro López-Samanes  Diego Moreno-Pérez  José L. Maté-Muñoz  Raúl Domínguez  Jesús G. Pallarés  Ricardo Mora-Rodriguez 《Journal of sports sciences》2017,35(21):2121-2128

To determine the effect of circadian rhythm on neuromuscular responses and kinematics related to physical tennis performance, after a standardised warm-up, 13 highly competitive male tennis players were tested twice for serve velocity/accuracy (SVA), countermovement vertical jump (CMJ), isometric handgrip strength (IS), agility T-test (AGIL) and a 10-m sprint (10-m RUN). In a randomised, counter-balance order, tennis players underwent the test battery twice, either in the morning (i.e., AM; 9:00 h) and in the afternoon (i.e., PM; 16:30 h). Paired t-tests were used to analyse differences due to time-of-day in performance variables. Comparison of morning versus afternoon testing revealed that SVA (168.5 ± 6.5 vs. 175.2 ± 6.1 km · h^?1; P = 0.003; effect size [ES] = 1.07), CMJ (32.2 ± 0.9 vs. 33.7 ± 1.1 cm; P = 0.018; ES = 1.46), AGIL (10.14 ± 0.1 vs. 9.91 ± 0.2 s; P = 0.007; ES = 1.23) and 10-m RUN time (1.74 ± 0.1 vs. 1.69 ± 0.1 s; P = 0.021; ES = 0.67) were significantly blunted during the morning testing. However, IS was not affected by time-of-day (P = 0.891). Thus, tennis performance may be reduced when competing in the morning in comparison to early evening. Therefore, coaches and tennis players should focus on schedule the SVA, power, speed and agility training sessions in the afternoon.  相似文献   

对我国优秀男子跳远运动员劳剑峰起跳技术的生物力学分析   总被引：1，自引：0，他引：1  

许延威 《浙江体育科学》2004,26(1):37-39

对劳剑峰九运会决赛最佳跳次的技术录像进行解析,结合专项理论并与国外优秀运动员的技术统计数据对比,得出: 1. 适宜增加起跳阶段的水平速度损失率,从而加大腾起角度,使起跳离地瞬间的水平速度和垂直速度的匹配更加合理,是改善起跳效果和提高成绩的重要途径.2. 改善起跳阶段的技术,减小着地脚和起跳阶段的扇面角,增大离地角是技术改进的方向.3. 加强膝关节快速用力条件下的退让式收缩能力和克制性收缩力量是专项力量训练的重点.  相似文献   

对目前我国部分优秀男子三级跳远运动员三跳速度变化的分析   总被引：3，自引：2，他引：1  

束景丹  冯伟  王三林 《北京体育大学学报》2003,26(3):408-409,414

通过对部分中国和外国优秀男子三级跳远运动员在三跳起跳瞬间(含上板瞬间)速度变化的分析对比,同时分析了在运动员的三跳中水平速度对三跳比例的影响,并结合三级跳远的专项理论,研究认为,相对于外国优秀男子三级跳远运动员,中国优秀男子三级跳远运动员上板速度较低、三跳中水平速度利用率较低,在第3跳时又未能获得足够的垂直速度,并针对性地提出建议。  相似文献   

速度空间的一个守恒量     

富中华 《大同职业技术学院学报》2004,(3)

本文从位形空间的牛顿第二定律出发,导出速度空间的一个守恒量,并且证明了在有心力场中存在这一守恒量.  相似文献   

论武术格斗的时空辩证关系     

叶代明  钱炳祥 《军事体育进修学院学报》2001,20(3):51-54

从体育哲学的时空辩证角度出发、在前人实践与理论研究基础上，通过献资料法，对武术格斗运动的对空辩证关系进行分析与研究，以指导武术格斗的实践运动。  相似文献   

我国男女三级跳远运动员三跳比例及对成绩的影响     

高寒  李翰君 《北京体育大学学报》2018,41(4):111-115

摘要：针对我国男女三级跳运动员的技术数据,通过调整运动员起跳时速度转换系数,模拟运动员可以达到最好成绩的三跳比例和技术类型,从而了解技术类型和速度转换系数对运动员成绩的影响。研究采用平面摄像与解析的方法,选取我国三级跳运动员男子7名和女子6名的比赛技术数据进行分析。应用Yu（1999）开发的三级跳模型对不同速度转换系数条件下3次跳跃距离进行模拟,分析每名运动员能够获得的最远实际三跳距离,以及相关的最佳跳跃技术类型和速度转换系数。结果显示,研究中的运动员存在可达到最大三跳距离的最佳三跳比例策略,如采用最佳三跳比例策略,可使比赛成绩平均提高70厘米以上。速度转换系数会影响最佳三跳比例。运动员可根据自己的能力和尽量减少损伤危险的基础上选择可以达到最大三跳远度的最佳三跳比例。  相似文献