共查询到19条相似文献，搜索用时 453 毫秒
1.
人体整体及环节的转动惯量是研究人体运动生物力学的基本参数。本文将100多年来国内外人体转动惯量的研究情况按尸体、活体和数学模型3种分类进行综述。不仅将前苏联、美国、德国等国外学者的研究进行对比，尤其是将近些年来引入计算机等先进科学技术的人体转动惯量测量的新方法以及中国人的人体转动惯量参数研究方面取得的突破性进展作了重点介绍。 相似文献
2.
我国蹦床网上单人项目现状的分析 总被引：2，自引：0，他引：2
本文分析了2000年悉尼奥运会蹦床比赛男、女单人决赛和2000年科健杯全国蹦床冠军赛男、女单人决赛。结果表明：我国男、女运动员的预跳能力、动作技术的稳定性和难度提高显著，与世界水平的差距日益缩小。全国女子冠军黄珊仙的水平已达到世界前列．提出了我国蹦床男、女单人项目与世界水平的一些差距，及现阶段我国蹦床运动训练重点问题。 相似文献
3.
4.
据《科技日报》消息：新世纪中国人民解放军在武器装备的研发上，正在改变原有观点更新和发展轻型武器系统。 传统的武器设计专家一直认为子弹在发射初期，发射药的燃烧是集中和稳定燃烧。但新的观察和测试说明具体细节上有不少出人，弹头在发射初期的做功还须进·步弄清楚，也就是说如果能让子弹的发射初速超过１０００米／秒，在其质量、转动惯量不变的情况下，子弹的侵彻力甚至能提高４０％。 自从１９世纪后，枪弹只是处在量化发展中，一直由弹壳、底火、发射药和弹头组成，如果能在这样硬件上进一步优化改良，我军轻武器的杀伤力，也就… 相似文献
5.
二传手是队伍中的核心，其情绪状态直接影响全队技战术水平的发挥。本文通过二传手与攻手情绪特征的分析，找出其中对二传手具有显著影响的动作稳定性，简单和复杂反应时，肌肉用力感、情绪控制力等方面的心理因素。旨在对二传手的心理训练、赛前调整以及选材等方面提供理论依据。 本文研究对象包括：南京体育学院、江苏省少体校男、女排，江苏省男、女排 34人，其中男队员 24人，女队员 10人，运动年限 5— 10年不等，文化程度均为高中以上。我们将所有人员分成攻手组和二传手组进行比较分析。测试结果如下： 从实验结果来看，二传… 相似文献
6.
一、短跑技术中肌肉放松的作用
肌肉放松能减小肢体的转动惯量，提高摆动角速度，提高频率。短跑中，从腿后蹬地结束脚离地面开始的屈膝前摆，是先屈膝关节，后屈髋关节。屈膝关节时，若充分放松傅展股肢肌，股内侧肌，股外侧肌，股中间肌就更有利于股后群肌肉坐近固定时向心收缩工作，使小腿靠近大腿折叠，缩短了向前摆腿的距离，使整个下肢绕髋关节轴的转动惯量减小， 相似文献
7.
本次比赛于10月15～18日在天津市武清区举行，来自全国的13个省市的185名运动员参加了比赛，其中男网44人，女网32人，男子单跳21人，女子单跳17人，参加技巧比赛的共有67名运动员：天津市体育局和武清区政府为本次比赛提供了最大的便利和一流的服务．保证了比赛的顺利进行。 相似文献
8.
在体育运动中,有许多运动项目都与转动有关,在研究转动规律过程中,必然涉及到转动惯量的问题。本文的目的是通过力学实验手段,介绍测定几种体育器械转动惯量的常用方法,探讨转动惯量在该种体育运动项目中的重要意义和对实践的指导价值。这些正是运动生物力学所要求的基本内容之一。 相似文献
9.
10.
对安徽115名运动员（男54人，女61人）的皮纹进行了研究。调查分析了指纹、掌纹和拓纹。结果表明：运动员的皮纹参数与对照组间有若干统计学差异。这些皮纹特征为运动员选材提供了参考指标。 相似文献
11.
The purpose of this study was to determine if warm-up with baseball bats of different moments of inertia has an effect on swing pattern and bat velocity. Ten experienced baseball players (ages 20-25 years) voluntarily participated in this study. Each participant was required to complete 10 dry swings (5 warm-up and 5 postwarm-up) at maximum effort within 3 different conditions. Post warm-up was always with a standard bat (I = .27 kgm2; 83.8 cm, 9.1 N). Warm-up for Condition 1 was with the standard bat. Condition 2 required participants to warm up with a standard bat plus a 6.1 N lead donut (I = .49 kgm2, 83.8 cm, 15.6 N). Condition 3 required participants to warm up with a hollow plastic bat (I = .08 kgm2; 83.8 cm, 3.34 N). Quantitative and qualitative analyses indicated that following warm-up with the weighted bat (largest moment of inertia), swing pattern was significantly altered, and post warm-up velocity was the lowest of the three conditions. 相似文献
12.
In the kinematic and kinetic analysis of human movement, an accurate assessment of the inertial properties of the body segments under investigation is often essential. Statistical and geometric models of the segments of the upper limb were examined to determine their ability to predict the moments of inertia of these segments. The cadaver data of Chandler et al. (1975) were used as the criteria with which computed values were compared. The regression equations of Hinrichs (1985) gave the most accurate results; the geometric models appeared to offer the greatest flexibility. 相似文献
13.
Abstract In the kinematic and kinetic analysis of human movement, an accurate assessment of the inertial properties of the body segments under investigation is often essential. Statistical and geometric models of the segments of the upper limb were examined to determine their ability to predict the moments of inertia of these segments. The cadaver data of Chandler et al. (1975) were used as the criteria with which computed values were compared. The regression equations of Hinrichs (1985) gave the most accurate results; the geometric models appeared to offer the greatest flexibility. 相似文献
14.
Abstract Some golf equipment manufacturers produce matched sets of golf clubs using an empirical method based on first moments of mass as well as shaft stiffness, whereas others claim to match sets on the basis of moment of inertia and dynamic considerations of shaft stiffness. This paper considers the significance of the mass distribution feature of club matching with regard to the parameters relating to physical exertion by the golfer. It is shown that dynamic considerations require a mass variation through the set almost identical to the variation prescribed by static swing weighting, and that conventionally static balanced golf clubs differ in mass by less than five percent from that suggested using a dynamic balance. It is also shown that the maximum driving force is relatively the same for a specific golfer using a variety of golf clubs but that the driving forces of the professionals were higher than those recorded for the amateurs. 相似文献
15.
The speed at which a player can swing a bat is central to the games of baseball and softball, determining, to a large extent,
the hit speed of the ball. Experimental and analytical studies of bat swing speed were conducted with particular emphasis
on the influence of bat moment of inertia on swing speed. Two distinct sets of experiments measured the swing speed of colege
baseball and fast-pitch softball players using weighted rods and modified bats. The swing targets included flexible targets,
balls on a tee and machine pitched balls. Internal mass alterations provided a range of inertial properties. The average measured
speeds, from 22 to 31 m s−1, are consistent with previous studies. Bat speed approximately correlates with the moment of inertia of the bat about a vertical
axis of rotation through the batter's body, the speed generally decreasing as this moment of inertia increases. The analytical
model assumes pure rotation of the batter/bat system about a vertical axis through the batter's body. Aerodynamic drag of
the batter's arms and the bat is included in the model. The independent variable is bat moment of inertia about the rotation
axis. There is reasonable agreement between the model and the measured speeds. Detailed differences between the two suggest
the importance of additional degrees of freedom in determining swing speed. 相似文献
16.
Clint Hansen Nasser Rezzoug Philippe Gorce Gentiane Venture Brice Isableu 《Journal of sports sciences》2016,34(9):878-885
We examined the role of rotation axes during an overarm throwing task. Participants performed such task and were asked to throw a ball at maximal velocity at a target. The purpose of this study was to examine whether the minimum inertia axis would be exploited during the throwing phases, a time when internal–external rotations of the shoulder are particularly important. A motion capture system was used to evaluate the performance and to compute the potential axes of rotation (minimum inertia axis, shoulder–centre of mass axis and the shoulder–elbow axis). More specifically, we investigated whether a velocity-dependent change in rotational axes can be observed in the different throwing phases and whether the control obeys the principle of minimum inertia resistance. Our results showed that the limbs’ rotational axis mainly coincides with the minimum inertia axis during the cocking phase and with the shoulder–elbow axis during the acceleration phase. Besides these rotation axes changes, the use of interaction torque is also sequence-dependent. The sequence-dependent rotation axes changes associated with the use of interaction torque during the acceleration phase could be a key factor in the production of hand velocity at ball release. 相似文献
17.
Seven 6 s sprints with 30 s recovery between sprints were performed against two resistive loads: 50 (L50) and 100 (L100) g x kg(-1) body mass. Inertia-corrected and -uncorrected peak and mean power output were calculated. Corrected peak power output in corresponding sprints and the drop in peak power output relative to sprint 1 were not different in the two conditions, despite the fact that mean power output was 15-20% higher in L100 (P < 0.01). The effect of inertia correction on power output was more pronounced for the lighter load (L50), with uncorrected peak power output in sprint 1 being 42% lower than the corresponding corrected peak power output, while this was only 16% in L100. Fatigue assessed by the drop in uncorrected peak and mean power output in sprint 7 relative to sprint 1 was less compared with that obtained by corrected power values, especially in L50 (drop in uncorrected vs. corrected peak power output: 13.3 +/- 2.2% vs. 23.1 +/- 4.1%, P < 0.01). However, in L100, the difference between the drop in corrected and uncorrected mean power output in sprint 7 was much smaller (24.2 +/- 3.1% and 21.2 +/- 2.7%, P < 0.01), indicating that fatigue may be safely assessed even without inertia correction when a heavy load is used. In conclusion, when inertia correction is performed, fatigue during repeated sprints is unaffected by resistive load. When inertia correction is omitted, both power output and the fatigue profile are underestimated by an amount dependent on resistive load. In cases where inertia correction is not possible during a repeated sprints test, a heavy load may be preferable. 相似文献
18.
Kadota K Matsuo T Hashizume K Tezuka K 《Research quarterly for exercise and sport》2004,75(2):138-147
We examined changes in the usage of muscular and motion-dependent moments during the long-term practice of a complex, multijoint movement. Seven participants practiced a cyclic movement of the upper limbs until their joint angular movements conformed to those of an expert. The motions of the participants were digitally recorded using four high-speed infrared cameras, and the joint kinematics and kinetics of the right arm were calculated. Practice brought about changes in the patterns of the net joint moment and in the contributions of the muscular and motion-dependent moments to the net moments. Practice also brought about a growing opposition between the directions of the two moments. These changes seemed to be important for improving the dynamic equilibrium of the movements. 相似文献
19.
Wycliffe W. Njororai Simiyu 《Soccer & Society》2019,20(7-8):973-985
ABSTRACTThis article looks at the memorable and defining moments that shaped the history of Africa’s participation in the World Cup. In this context ‘memorable’ refers to moments in the tournament that were attractive in terms of style of play, impact of the outcome and historical legacy. Closely related to memorable is the concept of ‘defining moments’. According to Badaracco (1997), defining moments have three characteristics: they reveal, they test, and they shape. Although this definition applies to leadership, it is used here to identify some defining moments that shaped the history of African soccer at the World Cup final tournaments preceding 1970 and in the subsequent tournaments till 2018. Although past performances by African teams have not yielded a championship trophy, there have been memorable and defining moments at each tournament that inspire hope for abreakthrough sooner than later.Abbreviations: CAF- Confederation of African Football; FIFA- Federation of International Football Associations 相似文献