短跑前支撑阶段动力学分析

运用信息技术和理论分析的方法对琼斯跑的下肢技术进行了动力学分析，对短跑的动力学部分经典观点提出了质疑。研究指出，短跑的支撑时期是一个连续的动作过程，整个支撑时期各阶段的技术对人体向前运动均起积极作用。从动态上看，着地和退让阶段技术不是被动和消极的过程，而是一个主动和积极地由前上方向后下方施力的过程，该力所产生的支撑反作用力与人体向前跑进方向一致，对人体位移动起拉引作用。     

短跑支撑阶段运动生物力学分析

采用测力、高速录像及特殊的数据平滑处理方法研究短跑运动员途中跑技术的运动学和动力学特征,进行田径技术原理的探索。结果表明,支撑时期可以分为着地阶段和蹬伸阶段,蹬伸阶段可分前蹬,后蹬前段,后蹬后段。途中跑前蹬段是人体重心垂直方向向上加速的重要时刻,前蹬时下肢一定程度的垂直加速用力虽影响水平速度,但对提高垂直速度有积极意义,前蹬和后蹬前段是身体重心垂直向上加速运动的阶段。着地缓冲后的前蹬用力也是实现良好成绩的技术之一。途中跑着地和前蹬阶段失去的水平速度损失完全可以从后蹬中得到补充。着地点过近对前支撑阶段获得重要的垂直速度不利,支撑阶段离地前的20ms身体重心速度已经开始下降。     

短跑运动生物力学——运动学研究现状

在回顾总结前人采用运动学测量方法在短跑运动中取得的成就的基础上,认真分析了该领域研究中的不足,并展望了今后的研究方向。     

短跑途中跑支撑阶段影响水平速度因素的运动学分析

运用激光测速系统、运动学分析系统以及多参数同步触发系统,在上海2名优秀短跑运动员的100 m跑训练过程中进行测试,将运动员100 m途中跑支撑阶段的运动学参数与人体运动的水平速度进行同步分析,来揭示短跑运动员100 m途中跑速度的变化规律,讨论和分析短跑运动员100 m途中跑支撑阶段的不同运动学参数的变化与人体速度的关系,为教练员和运动员提高短跑途中跑的速度和改进技术动作提供一定的数据参考和理论依据。     

影响短跑途中跑前支撑阶段水平速度的主要因素

短跑途中跑前支撑阶段(缓冲阶段)的技术是田径运动和运动生物力学研究的重点之一。本文依据运动生物力学研究理论,寻找出影响前支撑阶段人体总重心水平速度的因素:(一)摆动腿大腿角速度;(二)着地角;(三)着地瞬间看地脚的向前水平速度;(四)前摆上臂角速度。     

短跑着地缓冲的运动生物力学分析

对短跑的动力来源问题、缓冲时相问题、缓冲距离问题等关键性的特点问题进行探讨与分析,从生物力学的角度短跑着地缓冲的动作进行分析,并探究了影响着地缓冲的若干因素,以期完善人们对该动作的认识,服务训练。     

短跑途中跑支撑摆动技术生物力学机制研究

研究目的:深入认识短跑途中跑支撑摆动动作系统中各环节协同的关系,完善短跑技术和专项力量训练理论。研究方法:采用生物力学测试、系统分析和数理统计等方法。结论:优秀运动员支撑摆动技术的主要运动学趋势,是支撑腿和摆动腿的髋角、膝角和踝角在支撑过程中均较小,两大腿的剪绞速度更快、幅度更大;短跑技术的本质特征是两大腿以髋为轴的剪绞—制动;积极着地是合理的短跑技术的基础;途中跑中前支撑段的技术效果是提高和保持最高跑速的主要影响因素;跑的主要动力是体后支撑阶段与人体运动方向相同的支撑反作用力的水平分力;两大腿的剪绞—制动力量和支撑腿膝、踝关节的低位趋等长力量,是短跑专项力量的核心。     

从短跑支撑技术的发展看体育专业短跑教学

随着短跑技术的发展，“屈蹬”技术的出现，与体育专业传统的充分后蹬教学理论与方法产生了较大的矛盾。为运用现代信息技术和运动学的方法，对世界顶级短跑运动员和体育教育专业学生的支撑技术进行了比较研究，得出了体育专业学生后蹬技术教学应采取“多元化”方法的结论。     

我国优秀女子皮艇运动员艇上划桨的运动生物力学测试与评定研究

采用德国产划桨测力系统对11名女子皮艇运动员进行了跟踪测试，同时测试生理和生化指标并综合分析。结果显示，在500m全程中，出发的最大划桨力量为320N，途中为250N，冲刺为270N。全程平均划桨力量为130N。划桨周期中支撑与非支撑阶段的比例为65％：35％和70％：30％。多人艇跟桨手的平均力量和最大力量优于领桨手。我国女子皮艇运动员与世界优秀选手差距在平均力量和平均划桨功率上。     

对人体支撑反作用力的测试及运动生物力学分析

应用进口Kisder三维测力平台,对人体下蹲、蹬起运动过程中支撑反作用力进行实验测试,以验证运动生物力学中的“失重”、“超重”现象,并对运动生物力学教材中(1)人体产生“失重”和“超重”的原因是由于“惯性力”的作用,(2)“惯性力”能对人体产生反作用力等问题,提出了不同看法。     

短跑技术中支撑与摆动的辨证关系

在查阅歇资料和调查访问的基础上，经过理论研究和实践论证后认为，人体水平加速的原动力是摇动腿的折叠前摆与支撑腿的快速伸髋在时空上的巧妙配合；支撑和摆动相互作用，相互影响，二在短跑的不同阶段所起的作用大小不同；提高摆动的速度和幅度是提高跑速的决定因素。     

Control of propulsion and body lift during the first two stances of sprint running: a simulation study

The aim of this study was to relate the contribution of lower limb joint moments and individual muscle forces to the body centre of mass (COM) vertical and horizontal acceleration during the initial two steps of sprint running. Start performance of seven well-trained sprinters was recorded using an optoelectronic motion analysis system and two force plates. Participant-specific torque-driven and muscle-driven simulations were conducted in OpenSim to quantify, respectively, the contributions of the individual joints and muscles to body propulsion and lift. The ankle is the major contributor to both actions during the first two stances, with an even larger contribution in the second compared to the first stance. Biarticular gastrocnemius is the main muscle contributor to propulsion in the second stance. The contribution of the hip and knee depends highly on the position of the athlete: During the first stance, where the athlete runs in a forward bending position, the knee contributes primarily to body lift and the hip contributes to propulsion and body lift. In conclusion, a small increase in ankle power generation seems to affect the body COM acceleration, whereas increases in hip and knee power generation tend to affect acceleration less.     

关于短跑速度障碍问题的探讨

根据速度障碍定义．分析了产生速度障碍的生理、技术、专项素质、力量、训练科学性、放松能力、柔韧性和关节的灵活性等七个方面的原因，阐述了防止和克服速度障碍的措施以及变破速度障碍的训练方法。     

Effect of postural changes on 3D joint angular velocity during starting block phase

Abstract

Few studies have focused on the effect of posture during sprint start. The aim of this study was to measure the effect of the modification of horizontal distance between the blocks during sprint start on three dimensional (3D) joint angular velocity. Nine trained sprinters started using three different starting positions (bunched, medium and elongated). They were equipped with 63 passive reflective markers, and an opto-electronic Motion Analysis® system was used to collect the 3D marker trajectories. During the pushing phase on the blocks, norm of the joint angular velocity (NJAV), 3D Euler angular velocity (EAV) and pushing time on the blocks were calculated. The results demonstrated that the decrease of the block spacing induces an opposite effect on the angular velocity of joints of the lower and the upper limbs. The NJAV of the upper limbs is greater in the bunched start, whereas the NJAV of the lower limbs is smaller. The modifications of NJAV were due to a combination of the movement of the joints in the different degrees of freedom. The medium start seems to be the best compromise because it leads, in a short pushing time, to a combination of optimal joint velocities for upper and lower segments.     

人体腰椎在发力动作中的受力特点与运动损伤

腰椎生物力学的参数显示腰椎在发力动作中主要受弯矩和压力作用。外负荷和肌力是影响腰椎载荷的主要因素，其中以肌力为主，肌力值足外负荷的9-10倍。髋关节角度越大，外负荷能力越强，180^。时，达到最大。减少腰椎负荷最有效的办法是通过伸髋展体减小阻力臂以减少弯矩。     

Effect of ischemic preconditioning on repeated sprint ability in team sport athletes

This study investigated whether ischemic preconditioning (IPC) in a trained population affected repeated sprint performance. A secondary aim was to assess responses according to gender. Sixteen (nine females and seven males) well trained team sport athletes took part in a randomised crossover study design. Participants underwent an IPC and placebo treatment involving three periods of 5 min occlusion applied unilaterally (3 × 5 min occlusion to each leg) at either 220 mmHg or 50 mmHg. Each period of occlusion was followed by 5 min reperfusion. Following treatment 5 × 6 s maximal effort sprints were undertaken on a cycle ergometer against 7.5% body mass, each interspersed by 24 s recovery. Measured parameters included peak power, total power, percentage decrement, post-exercise blood lactate and ratings of perceived exertion. Nor within subject main effect for IPC was observed, neither was there an interaction effect with gender. Effect sizes were trivial (ES < 0.2) with the exception of a moderate (ES < 1.2) change in post-exercise blood lactate in the female cohort (1.6 ± 0.4 mmol^?1 lower following IPC). Results suggest no benefit to team sport players in utilising IPC as a means of enhancing repeated sprint performance. A lower blood lactate response in female participants following IPC may suggest improved blood flow through vasodilation.     

Effects of weighted sled towing on ground reaction force during the acceleration phase of sprint running

Abstract

Athletes use weighted sled towing to improve sprint ability, but little is known about its biomechanics. The purpose of this study was to investigate the effect of weighted sled towing with two different loads on ground reaction force. Ten physically active men (mean ± SD: age 27.9 ± 1.9 years; stature 1.76 ± 0.06 m; body mass 80.2 ± 9.6 kg) performed 5 m sprints under three conditions; (a) unresisted, (b) towing a sled weighing 10% of body mass (10% condition) and (c) towing a sled weighing 30% of body mass (30% condition). Ground reaction force data during the second ground contact after the start were recorded and compared across the three conditions. No significant differences between the unresisted and 10% conditions were evident, whereas the 30% condition resulted in significantly greater values for the net horizontal and propulsive impulses (P < 0.05) compared with the unresisted condition due to longer contact time and more horizontal direction of force application to the ground. It is concluded that towing a sled weighing 30% of body mass requires more horizontal force application and increases the demand for horizontal impulse production. In contrast, the use of 10% body mass has minimal impact on ground reaction force.