跳远起跳速度研究综述

采用文献综述法,对影响跳远起跳速度的有关因素进行分析。结果表明：提高助跑速度和助跑最后二步节奏,有利于加快起跳速度;适宜的阗地角是加大上板速度、获得较大冲击力的前提;较早的蹬伸能获得较长的重心工作距离,缩短起跳时间,提高起跳效果。     

2010年全国田径锦标赛苏雄锋跳远技术分析

选取了参加2010年全国田径锦标赛暨亚运会选拔赛冠军苏雄锋和2009年德国世界田径锦标赛男子跳远决赛的前8名运动员为研究对象,运用运动学参数分析了运动员的倒3步步长、倒3步速度特征、起跳技术和落地技术特征,认为苏雄锋的起跳技术比较合理,但助跑速度还有待提高,空中动作控制能力需要改善。     

从不同高度下落到不同硬度的地面上下肢关节的力学响应

本研究了人从30cm和60cm高度下落到两种不同硬度的地面，即木板地面和海绵垫上时下肢关节的力学响应。结果表明从两种高度下落到海绵垫上比落到木板地面时下肢关节的受力、力矩显减小，关节的角度变化显增加，从着地到落地停稳所用的时问显增加。各关节力矩是外力矩与肌肉力矩共同作用的结果，正确的落地技术应该是三个关节的力矩同时减小，掌握正确的落地技术的实质是掌握正确的肌肉被拉伸与收缩的顺序和大小。从30cm和60cm下落着地后，不论是何种地面条件。三个关节的力矩以髋关节力矩为最大，膝和踝关节肌肉是在髋关节控制下起互相协调作用。     

Gender differences in lower limb frontal plane kinematics during landing

The aim of this study was to investigate gender differences in knee valgus angle and inter-knee and inter-ankle distances in university volleyball players when performing opposed block jump landings. Six female and six male university volleyball players performed three dynamic trials each for which they were instructed to jump up and block a volleyball suspended above a net set at the height of a standard volleyball net as it was spiked against them by an opposing player. Knee valgus/varus, inter-knee distance, and inter-ankle distance (absolute and relative to height) were determined during landing using three-dimensional motion analysis. Females displayed significantly greater maximum valgus angle and range of motion than males. This may increase the risk of ligament strain in females compared with males. Minimum absolute inter-knee distance was significantly smaller, and absolute and relative inter-knee displacement during landing significantly greater, in females than males. Both absolute and relative inter-ankle displacement during landing was significantly greater in males than females. These findings suggest that the gender difference in the valgus angle of the knee during two-footed landing is influenced by gender differences in the linear movement of the ankles as well as the knees. Coaches should therefore develop training programmes to focus on movement of both the knee and ankle joints in the frontal plane in order to reduce the knee valgus angle during landing, which in turn may reduce the risk of non-contact anterior cruciate ligament injury.     

2011年末中国经济软着陆问题研究

2010年以来,中国和其他新兴市场经济体一样面临着比较严重的通货膨胀问题,经济明显出现过热现象.为了控制通货膨胀,中国政府灵活运用各种政策工具,终于在2011年末出现经济软着陆的趋势,通胀问题得到妥善解决.经济软着陆为中国经济的进一步发展打下良好的基础,促进中国经济的平稳较快增长,对世界经济的复苏做出一定的贡献.     

支撑跳跃动作的技术分析

通过对支撑跳跃技术动作的分析 ,进一步明确支撑跳跃各阶段的技术特点 ,为搞好支撑跳跃教学与训练提供科学的参考依据 .     

论新课程改革的“软着陆”

新课程改革需要“软着陆”,是指课改的进程要减慢速度,课改的实施要稳步成功。钟启泉教授的一篇对新课程改革的总结性《对话》提出的一系列观点,都不利于课程改革的“软着陆”,是对课程改革的误导。这些误导表现出了西方后现代理论在中国课程改革中的一种思潮。新课程改革如何“软着陆”,这需要以“科学发展观”为指导。     

Mechanisms of anterior cruciate ligament injuries in elite women’s netball: a systematic video analysis

This study involved a systematic video analysis of 16 anterior cruciate ligament (ACL) injuries sustained by elite-level netball players during televised games in order to describe the game situation, the movement patterns involved, the player’s behaviour, and a potential injury mechanism. Eight of the ACL injuries were classified as “indirect contact” and eight as “non-contact”. Two common scenarios were identified. In Scenario A the player was jumping to receive or intercept a pass and whilst competing for the ball experienced a perturbation in the air. As a result the player’s landing was unbalanced with loading occurring predominantly on the knee of the injured side. In Scenario B the player was generally in a good position at ground contact, but then noticeably altered the alignment of the trunk before the landing was completed. This involved rotating and laterally flexing the trunk without altering the alignment of the feet. Apparent knee valgus collapse on the knee of the injured side was observed in 3/6 Scenario A cases and 5/6 Scenario B cases. Players may benefit from landing training programmes that incorporate tasks that use a ball and include decision-making components or require players to learn to cope with being unbalanced.     

Shock and impact reduction in moderate and strenuous landing activities

Shock reduction has been well studied in moderate activities such as walking and running. However, there is a clear lack of research concerning shock wave transmission and reduction in more strenuous landing activities. In this study, we examined the impact of shock transmission and reduction in landing activities with varied mechanical demands. Ten active males were recruited for the study. They performed five successful step-off landing trials from each of five heights: 30, 45, 60, 75, and 90 cm. Right sagittal kinematics, ground reaction forces, and acceleration were recorded simultaneously. Impact frequencies were analysed using a discrete Fast Fourier Transform and power spectral density was computed. Increased range of motion for the ankle, knee, and hip joints was observed at higher landing heights. The peaks of the vertical ground reaction force, forehead and tibial accelerations, and eccentric muscle work by lower extremity joints were increased with increased landing heights. The peak head power spectral density was severely attenuated at higher frequencies but the peak tibia power spectral density did not demonstrate this trend. Shock reduction showed increased reduction at higher frequencies, but minimal changes across five landing heights. Unlike the responses observed for walking and running, the shock reduction did not show significant improvement with elevated mechanical demands.