太极拳云手技术对脊柱曲度影响的实证研究

摘要：目的：通过太极拳云手技术对脊柱曲度影响的实证研究,探索太极拳形态的核心技术变化规律。方法：采用实验方法对高水平太极拳组和普通组进行对比研究。结果：高水平太极拳组,在太极拳云手动作的脊柱变化是脊柱胸腰段曲度在胸椎1～7节上没有明显变化,而从第8～12胸椎,包括全部的5节腰椎,整体上都存在比较大的后凸趋势,且呈现出逐节递增的变化特征。结论：1）太极拳形的核心要素是脊柱的生理弯曲减小,由“S”型变化“C”型,形成近似“中直”的轴形。太极拳运动能够对人体脊柱的曲度和活动度起到很大的锻炼功效,有长期太极拳练习经历的人群,在对脊柱曲度变化的调节和控制能力上要明显优于短时间或无太极拳练习基础的人。2）受传统“中庸思想”影响和太极拳攻防化劲发力要求形成了太极拳形的“中直”脊柱形态变化。3）脊柱生理弯曲改变,使脊柱椎间盘受力均匀,深层肌肉得到锻炼,可以有效缓解和治疗脊柱疼痛等脊柱疾病,有助健康。4）依据研究结果提出“靠墙站桩”简易健身方法。     

The effects of player grip on the dynamic behaviour of a tennis racket

The aim of this article is to characterise the extent to which the dynamic behaviour of a tennis racket is dependent on its mechanical characteristics and the modulation of the player’s grip force. This problem is addressed through steps involving both experiment and modelling. The first step was a free boundary condition modal analysis on five commercial rackets. Operational modal analyses were carried out under “slight”, “medium” and “strong” grip force conditions. Modal frequencies and damping factors were then obtained using a high-resolution method. Results indicated that the dynamic behaviour of a racket is not only determined by its mechanical characteristics, but is also highly dependent on the player’s grip force. Depending on the grip force intensity, the first two bending modes and the first torsional mode frequencies respectively decreased and increased while damping factors increased. The second step considered the design of a phenomenological hand-gripped racket model. This model is fruitful in that it easily predicts the potential variations in a racket’s dynamic behaviour according to the player’s grip force. These results provide a new perspective on the player/racket interaction optimisation by revealing how grip force can drive racket dynamic behaviour, and hence underlining the necessity of taking the player into account in the racket design process.     

散打项目的博弈特点及各因素变化 规律分析

通过从宏观的角度对散打项目的制 胜规律进行研究,总结散打项目的制胜经验,减少训练的盲目性,提高训练的科学性,寻找其制胜规律以有力地推动散打运动训练科学化水平的提高,对促进我国散打项目的顺利发展有着很大的理论意义和现实意义。     

我军徒手格斗教学训练内容改革研究

军事上的徒手格斗是纯军事技术发展中不可或缺的一个组成部分,是军事训练的一个重要内容。军事格斗训练的目的在于提高官兵的尚武精神和使官兵掌握一定的格斗技能在战场上能够保存自己。因此部队的格斗训练必须以实用为本,注重对抗性练习,“为战而练”,绝不能华而不实。文章通过对外军和我军徒手格斗训练内容的分析比较,找出我军徒手格斗训练中所存在的主要问题,并提出相应的改革思路,期望能为我军的徒手格斗训练提供参考,以使我军的徒手格斗训练内容具备科学性、有效性,达到更好地为提高部队战斗力而服务的目的。     

提高正面上手发球攻击性的途径

正面上手发球是排球发球技术的基础．对于初学排球者是必须掌握的一项技术．由于身体素质,对动作的理解能力等方面的原因,往往是发出的球,“形似而神不似”．没有正面上手发球所应有的威力．本文探讨如何提高正面上手发球的攻击性的途径．     

浅论船长递交NOR的条件

阐述了在航次租船合同下,船长递交装卸准备就绪通知书所具备的各种条件及有关注意事项,以便更有效地保护船东利益。     

关于基础教育改革“政府推动模式”的几个问题

根据主导控制改革的主体不同,基础教育改革的模式分为政府推动模式、专家倡导模式和教师自觉模式三种。改革的政府推动模式是政府运用政策手段"自上而下"推动改革的展开,处理得好,可以迅速、全面、有效地解决现实中的问题,实现改革的目标;处理得不好,则会导致对理论和现实的全面性关照不够、相关参与人员对改革被动应对、行政指令对改革的规约过多过细等问题。运用基础教育改革的政府推动模式时,应该重视改革内容的现实性,强化政策制定的科学性,遵循政策实施的渐进性,明确政府权力的有限性。     

钢琴教学中常见问题解析

学钢琴不仅要有耐心,也要讲艺术。万事开头难,钢琴初学者在初学时会出现一些问题,例如：弓腰驼背,端肩吊臂,绞脚绕腿,压腕抖腕,掌僵指硬等毛病,而要学好钢琴就必须在刚入门时打好基础,要改正平时所出现的毛病,要端正坐姿,放松胳膊,稳定手腕,支撑手掌,这样,才能在钢琴学习上取得好的成效。     

Age and Sex Differences in Controlled Force Exertion Measured by a Computing Bar Chart Target-Pursuit System

This study aimed to examine the age and sex differences in controlled force exertion measured by the bar chart display in 207 males (age 42.1 ± 19.8 years) and 249 females (age 41.7 ± 19.1 years) aged 15 to 86 years. The subjects matched their submaximal grip strength to changing demand values, which appeared as a moving bar chart on the display of a personal computer. The subjects performed the controlled force exertion test using the dominant hand three times with 1-min intervals (one trial was 40 sec) after one practice trial. A total of the differences between the demand value and the grip exertion value for 25 sec was used as the evaluation parameter. The errors in controlled force exertion showed a right-skewed distribution in both sexes but showed a normal distribution after logarithmic transformation (males, W = .06; females, W = .74; p > .05). In addition, the errors in controlled force exertion tended to increase constantly with age in both sexes. Significant linear regressions were identified (r ² _males = .88, r ² _females = .81), but there was no significant difference in the increase rate of both sexes. The results of the analysis of variance and multiple comparisons showed insignificant sex differences among means, except for those in individuals older than 70 years; significant differences between means in the older than 40-year-old age group and the 20-year-old age group were found in both sexes. Individual differences were almost the same in both sexes (CV_males = 20.0～34.8, CV_females = 17.7～36.2). Errors in controlled force exertion showed a nonsignificant sex difference and increased gradually with age in both sexes but increased remarkably with age after 40 years of age.     

The effect of perceived streakiness on the shot-taking behaviour of basketball players

Abstract

We examine behavioural changes of basketball players arising from the hot-hand belief and use data of 1216 National Basketball Association games to measure the effect of cold and hot streaks on three proxies of shot difficulty. We find that the more consecutive shots players make (miss), the more difficult (easier) shots become along the three dimensions. Furthermore, most players' performance seems to improve during hot streaks because they attempt more difficult shots while no significant decrease in shooting accuracy takes place. This might explain why most previous studies could not find empirical evidence for the hot-hand belief in basketball when considering in-game field goal shooting.