共查询到20条相似文献，搜索用时 515 毫秒
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Ihor Zanevskyy 《Sports Engineering》2012,15(3):167-175
The aim of the research was to create a mechanical and mathematical model of a compound bow and analyse its work without any prior hypothesis about the symmetry of limb deflection. The method of the research was based on the methods of theoretical mechanics, applied and computer mathematics. A pair and shift mechanism with cams and levels was used as a basis of the mechanical and mathematical model of a compound bow. The difference between results of modelling and measurement was near 7?%, while the error due to digital image deformation was evaluated to be near 1?% which was considered as acceptable. The calculated results indicated noticeable differences from simulations using the constraint of symmetrical limb deformation. Comparison of symmetrical and asymmetrical simulations with experimental data revealed that the asymmetrical simulation gave a closer match to the measured values for cam angles; the simulated and measured cam angle asymmetry was much greater than any measurement errors. Realisation of a process of solving the problem using computer mathematical system MathCAD makes it possible for specialists of physical education and sports (coaches and sport archers), who do not have a mathematical background, to use the mechanical and mathematical model that was proposed in the research for a study and training process. 相似文献
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目的:开发一种新的液态金属应变传感器对射箭动作拉力进行监控。方法:设计和制造液态金属应变传感器,标定传感器的信号值与拉力之间的关系并对健将级运动员射箭的拉力特征进行分析。结果:(1)研发的传感器可以测量0%~160%之间的应变;在重复拉伸1 500次的过程后,信号变化率小于1.5%。(2)传感器最佳位置为离弓稍92 mm处,该处拉力拟合值与实际值的偏差范围为0.5%~2%。(3)实时反馈了运动员王X射箭不同动作阶段拉力图像,监控了关键阶段的力和时间。结论:(1)本液态金属应变传感器具有较好的可重复性和有效性。(2)重点监控了射箭瞄准阶段、声动反应阶段的拉力和时间,弥补了前人对射箭拉力的研究空白,为提高射箭竞技水平提供实验数据支撑。 相似文献
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Recurve archery is an Olympic sport that requires extreme precision, upper body strength and endurance. The purpose of this research was to quantify how postural stability variables both pre- and post-arrow release, draw force, flight time, arrow length and clicker reaction time, collectively, impacted on the performance or scoring outcomes in elite recurve archery athletes. Thirty-nine elite-level recurve archers (23 male and 16 female; mean age?=?24.7?±?7.3 years) from four different countries volunteered to participate in this study prior to competing at a World Cup event. An AMTI force platform (1000Hz) was used to obtain centre of pressure (COP) measurements 1s prior to arrow release and 0.5s post-arrow release. High-speed footage (200Hz) allowed for calculation of arrow flight time and score. Results identified clicker reaction time, draw force and maximum sway speed as the variables that best predicted shot performance. Specifically, reduced clicker reaction time, greater bow draw force and reduced postural sway speed post-arrow release were predictors of higher scoring shots. It is suggested that future research should focus on investigating shoulder muscle tremors at full draw in relation to clicker reaction time, and the effect of upper body strength interventions (specifically targeting the musculature around the shoulder girdle) on performance in recurve archers. 相似文献
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Experimental and theoretical research in archery 总被引：1，自引：0，他引：1
R Pekalski 《Journal of sports sciences》1990,8(3):259-279
The aim of this study was to introduce certain methods and research techniques and to present the results of experiments on parameters of archery equipment to optimize the interaction of the archer-bow-arrow system's elements. In order to achieve the research requirements, the following were devised: 1. A mathematical model of an arrow's movement during its interaction with a bow. 2. A mechanical model of an archer-bow-arrow system, which constitutes a device for mechanical loosing of an arrow from the bow strings (DMLA). 3. Three series of high-speed filming. The mathematical model and computer simulation were used to describe the arrow's movement for various initial conditions and various parameters of the equipment, based on which a nomogram was constructed of the optimum arrow parameters for bows of various draw forces. The device for the mechanical loosing of arrows from a bow was used to study the influence of selected parameters of the archer-bow-arrow system on the accuracy of shots. The film analysis was used to verify the mathematical and mechanical models constructed. 相似文献
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Abstract Subjects (21 men and 28 women) were tested for maximal pull and comfortable pull, were assigned bows on the basis of comfortable pull, were retested for maximal and comfortable pull after 24 lessons. Although there was some relationship between bow weight and comfortable pull when data were analyzed on a coeducational basis, there was no such relationship when the analysis was on a single sex basis. There was also no adaptation of kinesthetic perception of a comfortable pull to the amount of pull in a comfortable draw. 相似文献
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David Sundström 《Sports Engineering》2016,19(4):251-263
Bioenergetic models for exercise performance simulations and pacing strategy optimizations currently lag behind empirical knowledge in human bioenergetics. Therefore, the objective of this study was the construction of a four-compartment hydraulic bioenergetic model that incorporates separate oxidative phosphorylation of lipids and carbohydrates and describes the regulation of these energy substrates’ utilization. Furthermore, the aim was also to model efficiency and the impact of muscle fatigue and the force–velocity relationship on the maximal attainable rate of energy expenditure. The model is formulated with five systems of differential equations that regulates the fluid levels in three of the compartments, while the fat compartment energy is kept constant. Regulations had to be imposed on the system of compartments to achieve the desired carbohydrate dependent functionality and efficiency of the model. Equilibrium equations are modeled for the alactic compound composition and a constraint is modeled for the maximal energy expenditure rate, dependent on the intramuscular inorganic phosphate. A separate force–velocity relationship is modeled to constrain power output at low speeds and efficiency is modeled with a linear but off-set relationship between power output and rate of energy expenditure. The relative aerobic contribution to total energy expenditure showed good congruence with empirical results, while time to exhaustion was overestimated due to the constraint on maximal rate of energy expenditure. Therefore, further experimental studies are necessary for complete validation of the model. 相似文献
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Lara Elena Gomes Lucas Boeira Jefferson Fagundes Loss 《Journal of sports sciences》2017,35(10):936-944
This study examined whether Sanders’ model is suitable for estimating accurately the propulsive force generated by the hands’ motion in swimming comparing the calculated force obtained using the model and the measured force during an actual propulsive action. The measured and calculated forces were obtained from 13 swimmers who, while tethered, performed a sculling motion in a prone position for the purpose of displacing the body by moving it forward. Kinematic analyses were conducted to obtain the calculated force, while the measured force was obtained via the use of a load cell. The calculated force was lower than the measured force and accounted for only a small part of the variation in the measured force. The forces could not be used interchangeably, and there were fixed and proportional differences between them. Consequently, this study indicates that Sanders’ model is not suitable for estimating accurately the propulsive force generated by the swimmer’s hands during sculling motion. However, research that integrates analyses from different approaches could result in improvements to the model that would render it applicable for estimating the propulsive forces during movements that are characterised by directional changes of the hands. 相似文献
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采用德国IsoMed 2000等速肌力测试仪,对17名健将（健将组）和18名一级（一级组）男子举重运动员进行双侧髋、膝和踝关节60°/s、120°/s、180°/s和240°/s向心、离心（每种角速度5次）测试。探讨优秀男子举重运动员下肢关节不同角速度等速肌力的特征,比较健将与一级组间差异,对健将组下肢关节相对峰力矩与相对专项成绩进行Pearson相关分析,并建立抓、挺举与峰力矩多元线性回归方程。结果显示,优秀男子举重运动员的髋关节相对伸爆发力与相对抓举呈高度显著正相关,髋关节中速（120°/s）、膝踝关节相对伸爆发力与相对抓举呈中度显著正相关,而踝关节相对屈绝对力呈中度显著负相关;髋关节相对伸爆发力与相对挺举呈高度显著正相关,左膝（挺举弓步腿）相对中速（120°/s）、爆发力和踝关节相对爆发力与相对挺举呈中度显著正相关。 相似文献
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智勇 《西安体育学院学报》2008,25(5)
通过运用三维运动学分析的方法,对现阶段我国15名运动员32次的试掷进行研究发现,我国选手在最后用力中存在右脚着地瞬间躯干倾角偏大,身体对器械的超越不够,“满弓”形成瞬间上体抬起过大,上肢移过支撑点过早,右肘弯屈过大和提前用力等问题,缩短了最后用力的距离和幅度,造成“满弓”动作和用力效果不好等现象。 相似文献
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Ihor Zanevsky 《Sports Engineering》2006,9(2):77-86
Competition results in sport archery depend to a great extent upon the optimal combination of bow-arrow-archer system parameters.
A significant part of bow tuning is vertical adjustment, the aim of which is to give an arrow zero angle of attack. It is
conducted in a long and complicated manner and error correction takes a lot of time and effort. The goal of the research was
to create an analytical method to determine an optimal combination of bow parameters, which ensures zero angle of attack for
an arrow launched from a string. Mechanical and mathematical models of bow and arrow geometry in the vertical plane in braced
and drawn situations were investigated. An asymmetrical scheme, rigid beams, concentrated elastic elements and elastic string
were the main features of the model. Numerical results of a computer simulation are presented in tabular and graphical form,
which makes it easy for sportsmen and coaches to use. 相似文献
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Fine body movements and the cardiac cycle in archery 总被引：3，自引：1，他引：2
This study examined the relationships between postural sway, aiming time, the cardiac cycle time and the placement of the first finger movement within the electrocardiac cycle, with the quality of the arrow shot. A small group of elite male and female archers who shot either the recurve or the compound bow, freestyle or bare bow was used in this study. A total of 240 arrows were shot, classified as being of good, average or bad quality and analysed in detail. The analyses were undertaken over two occasions up to 100 days apart. The area of postural sway, as measured by the movement of the centre of pressure coordinates, varied significantly (P less than 0.05-0.001) both within and between trials for all archers and for all quality of arrows shot. There was a tendency for the area of postural sway to increase as the quality of the arrow shot decreased. This increase in postural sway exceeded, for arrows of bad quality, that exhibited as normal postural sway when standing relaxed and addressing the target with the hands at the side. Aiming time was variable within the quality of arrow shot, although it was consistent for each archer. In some cases the aiming time increased as the quality of the arrow decreased, whereas in the case of bare bow archery the aiming time tended to decrease as the quality of the arrow deteriorated. The cardiac cycle time increased significantly (P less than 0.05-0.01) as the archers approached the loose of the good quality arrows but there was no significant increase in cardiac cycle time when arrows of average or bad quality were shot. The most consistent parameter related to the quality of the shot was the placement of the first finger movement within the ST phase or the mid-cycle phase of the electrocardiogram for arrows of good quality (P less than 0.0001). 相似文献
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论赛艇动力学及提高赛艇技术的途径 总被引：6，自引：0，他引：6
用新型智能仪表SF2船速桨频测量仪采集数据,依据动量原理,建立赛艇动量方程及动力学方程。指出,桨手在滑座上移动时,人体质心动量变化产生的力在回桨和拉桨期都会各自交替产生动力和阻力,一般拉桨前期产生阻力,后期产生动力,回桨时相反。强调回桨质量,注意延长各段的动力作用时间,缩短阻力时间,加强低频训练和“意”练,让船速和桨频同步提高。 相似文献
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Eliseo Iglesias-Soler Juan Fariñas Xian Mayo Luis Santos Slobodan Jaric 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(2):174-189
The aims of this study were to compare the goodness of fit and the concurrent validity of three regression models of the force–velocity relationship in a unilateral knee extension exercise. The force–velocity relationship and the one-repetition-maximum load in the dominant and non-dominant leg were obtained in 24 male sports sciences students by a progressive protocol. Additionally, the maximum voluntary contraction (MVC) of the knee extensor muscles was recorded. Individual force–velocity relationships were obtained by the linear, quadratic polynomial and exponential regression models. Although the adjusted coefficients of determination of all three models were high, the polynomial model’s coefficient was slightly but significantly higher than the rest of the models (p < 0.05), while the standard error of estimate was slightly higher for the linear than for polynomial model (p = 0.001). MVC was underestimated by F 0 calculated from the linear and polynomial models, while the maximum power was accurately estimated by the linear model. In summary, while the polynomial model revealed somewhat better fit, the linear model more accurately estimates the maximum power and provides the parameters of apparent physiological meaning. Therefore, we recommend using the linear model in research and routine testing of mechanical capacities of knee extensors. 相似文献
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本文以新疆锡伯族传统弓箭文化的产业化为主要对象,通过阅读相关的书籍资料,得出锡伯族弓箭文化的发展历史及濒危现状,调查研究理清发展脉络,对存在的问题进行分析,并提出非物质文化遗产项目的顺利运作和政府推动民间组织的"三角模式"互动机制是弓箭文化产业化的重要发展对策。研究结果显示,弓箭文化产业化公司的成立在市场中占据很大的优势地位,建立弓箭文化产业化公司同时也在传承和保护锡伯族濒危的弓箭文化,对于国家级非物质遗产保护项目也有着重要的作用。 相似文献
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Olli Ohtonen Stefan Lindinger Teemu Lemmettylä Seppo Seppälä Vesa Linnamo 《Sports Engineering》2013,16(4):281-296
The aim of the present study was to design, construct and scientifically validate a two-dimensional force measurement binding system for cross-country skiing. The system consists of two force measurement bindings. One binding was designed for analysing classic skiing (vertical and anterior–posterior [along the ski] force components) and the other one for skate (freestyle) skiing (vertical and medio-lateral [transverse to the ski] force components). Validation was accomplished using a three-step process: (1) accuracy tests for the sensors in two temperatures, (2) sport-specific imitation jump test on standard force plates in a laboratory and (3) comparing the system against force measurement reference systems that are currently used when skiing on snow. During sport-specific imitation jumps, differences in peak forces and impulses between the classic binding and the reference systems ranged from 8.0 to 19.9 % and were two to three times greater compared to differences between the skate binding and the reference systems (range ?5.9 to 5.5 %). However, high similarity coefficients were observed with both bindings (classic binding 0.990–0.996, skate binding 0.996–0.999) compared to the reference systems. Based on these results, the skate binding was shown to be fully valid for use in field measurements of skate skiing, whereas some improvements have to be performed in the construction and sensor placements for the classic binding (vertical as well as anterior–posterior force component). 相似文献
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Pendar Hazrati Peter James Sinclair Wayne Spratford René Edouard Ferdinands Bruce Robert Mason 《Journal of sports sciences》2018,36(1):7-13
Active drag force in swimming can be calculated from a function of five different variables: swim velocity, tow velocity, belt force, power output and exponent of velocity. The accuracy of the drag force value is dependent on the accuracy of each variable, and on the contribution of each variable to drag estimation. To calculate uncertainty in drag value, first the derivatives of the active drag equation with respect to each variable were obtained. Second, these were multiplied by the uncertainty of that variable. Twelve national age and open level swimmers were recruited to complete four free swimming and five active drag trials. The uncertainties for the free and the tow swim velocities, and for the belt force, contributed approximately 5–6% and 2–3% error, respectively, in calculation of drag. The result of the uncertainty of the velocity exponent (1.8–2.6) indicated a contribution of about 6% error in active drag. The contribution of unequal power output showed that if a power changed 7.5% between conditions, it would lead to about 30% error in calculated drag. Consequently, if a swimmer did not maintain constant power output between conditions, there would be substantial errors in the calculation of active drag. 相似文献
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A new method was established for the continuous measurement of force applied from a springboard to a gymnast in vaulting (board reaction force). Male gymnasts performed a handspring vault using a springboard mounted on force platforms. A high-speed video camera sampled the springboard motion at 500 Hz. The springboard was initially partitioned into 29 segments. The force due to the accelerative motion of the springboard was determined by summing the forces of the individual segments. The board reaction force acting on the gymnast was calculated by subtracting the force due to the accelerative motion of the springboard and weight from the force recorded by the force platform. The new method succeeded in illustrating transient changes of the board reaction force. The horizontal and vertical components of the peak values of the board reaction force were three and two times greater respectively than the average values. A series of tests was conducted to determine whether the number of segments of the springboard model could be reduced without affecting accuracy. A model consisting of only four segments produced almost the same accuracy as the 29-segment model. The simplified model is recommended as a more efficient method to measure board reaction force. 相似文献
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刘朴 《山东体育学院学报》2008,24(10)
据汉代文献记载,汉代盛行射艺,但是由于历史文献多是对人物记述,故对射艺的具体细节未做详细描述,因而汉代弓射的动作及技术细节是一个千古之谜。通过汉画像石文物资料考察法和古文献资料研究法,揭示了汉代弓射分为徒步射和骑射两种。徒步弓射动作方式有立射、蹲射及跪射、折腰射、弓步射、转身背射、坐射、步行射和跑步射9种,骑射有静止的骑射和行进中的骑射两种方式。徒步和骑射的方向主要有向下、向前、向后等。射的目标有静止和移动两类。另外,弓射内容在汉画像石的狩猎图中多有发现,证明狩猎是弓射练习的重要手段。 相似文献