Dribbling determinants in sub-elite youth soccer players

Dribbling speed in soccer is considered critical to the outcome of the game and can assist in the talent identification process. However, little is known about the biomechanics of this skill. By means of a motion capture system, we aimed to quantitatively investigate the determinants of effective dribbling skill in a group of 10 Under-13 sub-elite players, divided by the median-split technique according to their dribbling test time (faster and slower groups). Foot-ball contacts cadence, centre of mass (CoM), ranges of motion (RoM), velocity and acceleration, as well as stride length, cadence and variability were computed. Hip and knee joint RoMs were also considered. Faster players, as compared to slower players, showed a 30% higher foot-ball cadence (3.0 ± 0.1 vs. 2.3 ± 0.2 contacts · s^?1, P < 0.01); reduced CoM mediolateral (0.91 ± 0.05 vs. 1.14 ± 0.16 m, P < 0.05) and vertical (0.19 ± 0.01 vs. 0.25 ± 0.03 m, P < 0.05) RoMs; higher right stride cadence (+20%, P < 0.05) with lower variability (P < 0.05); reduced hip and knee flexion RoMs (P < 0.05). In conclusion, faster players are able to run with the ball through a shorter path in a more economical way. To effectively develop dribbling skill, coaches are encouraged to design specific practices where high stride frequency and narrow run trajectories are required.     

The influence of shoe drop on the kinematics and kinetics of children tennis players

This study investigated the immediate effects of reducing the shoe drop (i.e. the difference between the heel and the forefoot height) on the kinematics and kinetics of the lower extremities of children tennis players performing a tennis-specific movement. Thirteen children tennis players performed a series of simulated open stance forehands wearing 3 pairs of shoes differing only in the drop: 0 (D0), 6 (D6) and the control condition of 12?mm (D12). Two embedded forceplates and a motion capture system were used to analyse the ground reaction forces and ankle and knee joint angles and moments of the leading lower limb. In D6 compared with D12, the peak impact force was reduced by 24% (p?=?.004) and the ankle was less dorsiflexed at foot strike (p?=?.037). In D0 compared with D12, the peak impact force was reduced by 17% (p?=?.049), the ankle was less dorsiflexed at foot strike (p?=?.045) and the knee was more flexed at foot strike (p?=?.007). In addition, 4 out of 13 participants (31%) presented a forefoot strike pattern for some of the trials in D0. No difference was observed across shoe conditions for the peak knee extensor moment (p?=?.658) or the peak ankle plantarflexor moment (p?=?.071). The results provide preliminary data supporting the hypothesis that for children tennis players, using a 6-mm lower shoe drop might reduce heel impact forces and thus limit potentially impact-related injuries.     

骨伤学科与力学学科的学科渗透与融合

分析了骨伤学科与力学学科分化与综合的发展历史。通过生物力学、动力学、振动力学等在骨伤学科中的应用,说明骨伤学科与力学的渗透与融合,也说明分化是学科发展的必要条件,综合是学科发展的必然趋势。     

决定标枪飞行远度因素的系统分析

在全面分析的基础上,画出了影响标枪飞行远度的因素的系统结构,对其中重要因素进行了定量和定性分析,使运动员和教练员可以全面、准确了解各因素对成绩影响以及它们之间的相互关系,从而对运动训练起到指导作用。     

略论运动生物力学的研究方法与测量技术

文章认为:1,仅依靠牛顿分析力学的研究方法,运动生物力学只能停留在“研究人体机械运动规律”的水平,“走出系统”的研究方法适合于对活体系统的生物力学研究;2,“理论模型”需数据支持才具有应用价值,“数据模型”需相应的数学化才具有理论意义;3,活体运动过程的测量应建立参数采集与测量的标准化和参数分析与评价的专家系统;4,应界定常规参数和敏感参数,并区别参数间的平行关系和因果关系,测量精度的提高主要应依靠测量参数数字化过程的分析方法的进步。     

对掷铁饼旋转技术的生物力学研究

运用影片解析的方法和运动生物力学理论, 针对掷铁饼旋转技术的特征进行分析, 为进一步研究掷铁饼技术提供了理论依据, 有助于教练和运动员正确认识掷铁饼技术     

沙滩排球扣球起跳动作协调性特征的运动生物力学研究

根据动作协调性理论并以室内排球为对照 ,采用理论分析与实验相结合的方法对沙滩排球扣球起跳阶段运动员的动作协调性进行了探讨。结果为 :沙滩排球扣球起跳阶段下肢髋 -膝 -踝运动链的运动基本上表现为同步性 ,而上肢 -躯干 -下肢运动链的运动则表现为顺序性 ;沙滩排球扣球起跳时肩关节发力过早影响了上、下肢动作的协调性 ;沙滩排球扣球起跳时人体两侧踝关节的非同步性导致了两侧自由下肢运动的非同步性 ,影响了扣球起跳的效果     

乒乓球弧圈球技术中"转髋"动作的生物力学分析

运用生物力学原理对弧圈球技术中的"转髋"动作加以分析,证实"转髋"动作能够提高挥拍角速度和线速度.阐明了"转髋"动作在弧圈球技术中的重要意义,为提高和改进弧圈球技术提供生物力学方面的理论依据.     

男子l500m跑时身体各环节输出功的初步研究

运动高速摄影和跑台气体代谢法对男子中长跑运动员进行了研究。通过测定运动员1500m跑步过程中身体各环节输出功,发现运动员身体各环节输出功的比例关系为;摆动腿占比例最大,其次是支撑腿,上肢和躯干的输出功的比例相当,头部所占比例很小。运动员跑步过程中,环节内和环节之间存在能量转换,且环节之间能量转换是主要的。     

扭转秋千测定Ⅰ的等时性分析及弹性扭转秋千的设计构想

扭转秋千测定人体转动惯量的关键在于是否具有谐振系统的等时性。受惠更斯设计不等长摆时钟的启发,经过数学的推演和力学的论证,提出可变臂长弹性扭转秋千的设计构想,并对等时性成立的最适扭转角作了详细的估算