Interaction of wrestling shoe and competition surface: effects on coefficient of friction with implications for injury

The purpose of this study was to determine whether there is a significant difference in the co-efficient of friction (Fc) between old versus new wrestling shoes and mats and to investigate the effect of perspiration. Fc was measured by dragging a weighted shoe over a wrestling mat surface and measuring the vertical and horizontal forces produced. Three different shoe conditions were assessed over two mat types for both wet and dry conditions for a total of 12 conditions. To simulate the wet condition, saline solution was smeared over the surface of the mat. There was a significant effect of shoe, mat, and wet/dry conditions. In addition, significant interactions of shoe by mat, shoe by dry/wet, and mat by dry/wet were observed. Overall, Fc was 36% higher for the new wrestling mat compared to the old wrestling mat. Application of the saline solution reduced Fc by 14% compared to the dry condition. Comparison of the mean Fc for all three shoe types revealed the Fc for the older design shoe was 23% to 28% lower than the brand new shoe and the worn newer design, respectively. A high Fc, such as in the new mat/new shoe combination, has the potential to increase the risk of knee and ankle injuries by fixing the foot more securely to the ground.     

The effect of torsional shoe sole stiffness on knee moment and gross efficiency in cycling

Altering torsional stiffness of cycling shoe soles may be a novel approach to reducing knee joint moments and overuse injuries during cycling. We set out to determine if the magnitude of three-dimensional knee moments were different between cycling shoe soles with different torsional stiffnesses. Eight trained male cyclists cycled at 90% lactate threshold power output in one of two cycling shoe conditions in a randomized crossover design. The shoe sole was considered torsionally flexible (FLEX) compared to a relatively stiffer (STIFF) sole. Gross efficiency (GE) and knee joint moments were quantified. No significant effect of shoe condition was seen in GE (21.4 ± 1.1% and 20.9 ± 1.6% for FLEX and STIFF, respectively, P = 0.12), nor in three-dimensional knee moments. 4 of the 8 subjects had reduced knee moments in at least 2 of the 3 moment directions. These “responders” were significantly shorter (1.73 ± 0.02 m vs 1.81 ± 0.04 m, P = 0.017) and had a higher relative maximal aerobic power (MAP) (4.6 ± 0.3 W?kg-1 vs 3.9 ± 0.3 W?kg-1, P = 0.024) compared to non-responders. These results suggest that certain shoe characteristics may influence certain individuals differently because these participants belong to different “functional groups”; certain individuals may respond positively to FLEX, while others may not. Further studies should test this proposed hypothesis.     

Running economy,mechanics, and marathon racing shoes

ABSTRACT

The choice of marathon racing shoes can greatly affect performance. The purpose of this study is to metabolically and mechanically compare the consumer version of the Nike Vaporfly 4% shoe to two other popular marathon shoes, and determine differences in running economy. Nineteen subjects performed two 5-minute trials at 4.44m/s wearing the Adidas Adios Boost (AB), Nike Zoom Streak (ZS), and Nike Vaporfly 4% (VP) in random order. Oxygen uptake was recorded during minutes 3–5 and averaged across both shoe trials. On a second day, subjects wore reflective markers, and performed a 3-minute trial in each shoe. Motion and force data were collected over the final 30 seconds of each trial. VP oxygen uptake was 2.8% and 1.9% lower than the AB and ZS. Stride length, plantar flexion velocity, and center of mass vertical oscillation were significantly different in the VP. The percent benefit of the VP over AB shoe was predicted by subject ground time. These results indicate that use of the VP shoe results in improved running economy, partially due to differences in running mechanics. Subject variation in running economy improvement is only partially explained by variation in ground time.     

Increased shoe bending stiffness increases sprint performance

The purposes of this investigation were to determine if increasing the bending stiffness of sprint shoes increases sprinting performance and to determine whether simple anthropometric factors can be used to predict shoe bending stiffness for optimal performance. Thirty-four athletes were tested using four different shoe conditions--a standard condition consisting of their currently used footwear and three conditions where the bending stiffness was increased systematically. The sprinters performed maximal effort 40 m sprints and their sprint times were recorded from 20 to 40 m. On average, increasing the shoe bending stiffness increased sprint performance. The stiffness each athlete required for his or her maximal performance was subject specific but was not related to subject mass, height, shoe size or skill level. It is speculated that individual differences in the force-length and force-velocity relationships of the calf muscles may influence the appropriate shoe stiffness for each athlete to obtain their maximal performance.     

学校体育教学中的中国式摔跤研究

文章采用文献资料、数据分析等方法,对我国学校体育教学中的中国式摔跤这一运动项目进行研究。结果发现：中国摔跤在我国学校体育教学中是以竞技传承的方式为主,开设该项目的院校具有局限性。中国式摔跤在学校的开展能提升现在学生的身体素质与心理素质,并且丰富学校体育教学内容。最后提出培养能胜任中国式摔跤教学的教师与加快学校体育意外伤害事故责任认定的立法是中国式摔跤在学校体育推广的必要条件。     

新规则对古典式摔跤的影响

根据古典式摔跤新规则改变的特点,采用文献资料法,结合我国十运会预决赛成绩统计和技术的分析。结果表明：十运会古典式摔跤预赛主要得分动作是站立＂过胸＂和＂转移＂;决赛主要得分动作是跪撑＂提抱＂和＂滚桥＂。比赛名次都有很大改变。     

The effect of shoe type on gait in forefoot strike runners during a 50-km run

PurposeTo observe the relative change in foot-strike pattern, pressure characteristics, surface electromyography (sEMG) recordings, and stride characteristics in forefoot strike runners wearing both minimalist and traditional shoes during a 50-km run.MethodsFour experienced minimalist runners were enrolled in this study. Each runner ran a 50-km simulated run in both minimalist shoes and traditional shoes. Pressure data, sEMG recordings, and limited 3D motion capture data were collected during the initial 0.8 km and final 0.8 km for each trial.ResultsThree runners in the traditional shoe type condition and one runner in the minimalist shoe type condition demonstrated a more posterior initial contact area (midfoot strike (MFS) pattern) after the 50-km run, which was supported by increased activity of the tibialis anterior in the pre-contact phase (as per root mean square (RMS) values). In addition, in both pre- and post-run conditions, there were increased peak pressures in the minimalist shoe type, specifically in the medial forefoot. Muscle fatigue as defined by a decreased median frequency observed in isometric, constant force contractions did not correspond with our hypothesis in relation to the observed foot strike change pattern. Finally, step rate increased and step length decreased after the 50-km run in both shoe type conditions.ConclusionMore runners adopted a more posterior initial contact area after the 50-km run in the traditional shoe type than in the minimalist shoe type. The runners who adopted a more posterior initial contact area were more closely associated with an increased median frequency of the medial gastrocnemius, which suggests there may be a change in motor unit recruitment pattern during long-distance, sustained velocity running. The increased peak pressures observed in the medial forefoot in the minimalist shoe type may predispose to metatarsal stress fractures in the setting of improper training.     

从摔跤规则演变看我国古典式摔跤技术的发展

针对摔跤新规则的特点 ,采用文献资料调研 ,结合九运会比赛执行新规则后的技术效果进行统计和分析。结果表明 :古典式摔跤站立技术的各种手法“转移”和“过胸摔”技术使用率和成功率都高于其它技术 ;古典式摔跤跪撑技术的“滚桥”和“提抱”技术是得分的主要手段 ,跪撑技术是比赛决定胜负的重要手段。预测了我国古典式摔跤技术发展趋势     

Can changes in midsole bending stiffness of shoes affect the onset of joint work redistribution during a prolonged run?

Purpose:This study aimed to investigate if changing the midsole bending stiffness of athletic footwear can affect the onset of lower limb joint work redistribution during a prolonged run.Methods:Fifteen trained male runners(10-km time of <44 min) performed 10-km runs at 90% of their individual speed at lactate threshold(i.e.,when change in lactate exceeded 1 mmol/L during an incremental running test) in a control and stiff shoe condition on 2 occasions.Lower limb joint kinematics and kinetics...     

新规则实施对女子散打技术运用的影响

竞赛规则是技术发展的导向,是裁决比赛胜利的准绳,是组织比赛和训练的依据。文章通过文献资料法、数理统计法、逻辑分析法、观摩法等研究方法探讨和分析新旧规则下我国散打技术的发展变化,总结比赛制胜规律,分析技术发展特点和导向,旨在为我国散打运动今后有针对性地训练提供理论和实践依据。研究发现：腿法技术是我国女子散打运动员主要的进攻手段和得分手段。拳法技术最主要是冲拳和贯拳,抄拳和鞭拳是边缘技术。鞭腿、侧踹、正蹬是腿法最主要技术;新规则实施后,拳法、腿法、摔法仍是女子散打运动员技术的主要的有机组成部分,但主要进攻技术手段的顺序发生了变化,腿法是最主要的进攻手段,其次是拳法和摔法。另外,摔法技术成功率大幅度下降,而腿法技术运用成功率明显增强;鞭腿是腿法技术中最主要的进攻手段和得分手段,其次是侧踹和正蹬。     

Anthropometric characteristics and body composition of Italian national wrestlers

Abstract

The aim of this study was to examine the anthropometric characteristics and body composition of wrestlers from the Italian national team. The study was carried out on a sample of 23 wrestlers (9 females and 14 males) aged 18–33 years. Various anthropometric measurements were performed (weight, height, sitting height, some girths and skinfold thicknesses) and anthropometric indices calculated (body mass index, cormic index, upper arm muscle area, upper arm fat area, and arm fat index). Body composition was assessed and minimum wrestling weight was determined based on a minimum body fat percentage of 5% for males and 12% for females. We undertook comparisons by sex, wrestling style (for males), and weight category. The comparison between men's and women's wrestling corroborated known differences between the sexes; the comparison between wrestling styles stressed the relevance of the cormic index. The most interesting finding of this study was that no female wrestler competed in a lower weight class than her minimum wrestling weight, even if all of them were heavier than values allowed for their weight class. Five of 14 male wrestlers competed in a weight class lower than their minimum wrestling weight, and all of them, except two, were heavier than the uppermost limit of their weight class.     

浅析摔跤运动在公安工作中的实用性

文章运用文献资料研究法,对目前公安工作的实际情况进行了分析研究,针对公安工作的特殊性与摔跤运动独特的训练要求,提出了在公安民警中开展摔跤运动的可行性和实用性,以期为摔跤运动在公安工作中能更好地开展提供理论依据。     

The influence of a new sole geometry while running

Abstract

Running shoe construction influences the forces experienced by the human body while running. The aim of this study was to ascertain whether the new sole architecture of the On running shoe reduces ground reaction forces compared with running barefoot or with a conventional running shoe and whether it changes the physiological parameters of running in shoes. Thirty-seven trained male participants were studied while running at submaximal speeds wearing their conventional running shoe, wearing the On running shoe and while barefoot. Additional biomechanical and physiological values were investigated to determine whether the On running shoe induced any changes in these parameters compared with conventional running shoes. The On exhibited similar ground reaction forces as conventional shoes, and these were different from the forces experienced while running barefoot, showing that the On was more similar to typical shoed running. No difference was observed in running economy between the On and a conventional shoe model. However, a slightly lower heart rate (HR) (≈1.3%) and blood lactate concentration (≈5.5%) were observed during submaximal running with the On running shoe compared with a conventional running shoe, as well as a greater lateral deviation of the centre of pressure mid-stance. The ramifications of the reduced HR and blood lactate concentration for competitive performance are unknown.     

关于足球鞋选用的分析

在现实的足球运动当中,许多球员(尤指业余爱好者)在球鞋选用方面都存在着一些问题,这十分不利于自我身心健康的发展和球技的有效发挥。为解决这一问题,对于足球鞋选用的理论探析则成为急切的必要条件。本文采用文本分析法和对比观察法,分析了不同特征的球员和各种类型的球鞋情况,认为足球运动员应自觉地根据自身的生理状况和踢球位置等特征来选择与之相适配的"战靴",以便在实际的活动中能够更加充分地发挥自己的驭球技艺,释放自我的运动激情,达成自我实现的目的。     

从新试行的2004年《武术散打竞赛规则》看散打运动的发展趋势

2004年《武术散打竞赛规则(试用)》出台。新旧规则相比，新规则的精神主要表现为：与国际武联制定的散打规则一致，便于与国际接轨；得分的标准和判罚更简洁；注重引导技术的发展和规范；注重踢、打、摔技术的均衡发展。     

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.     

Effects of forefoot bending stiffness of badminton shoes on agility,comfort perception and lower leg kinematics during typical badminton movements

This study investigated whether an increase in the forefoot bending stiffness of a badminton shoe would positively affect agility, comfort and biomechanical variables during badminton-specific movements. Three shoe conditions with identical shoe upper and sole designs with different bending stiffness (Flexible, Regular and Stiff) were used. Elite male badminton players completed an agility test on a standard badminton court involving consecutive lunges in six directions, a comfort test performed by a pair of participants conducting a game-like practice trial and a biomechanics test involving a random assignment of consecutive right forward lunges. No significant differences were found in agility time and biomechanical variables among the three shoes. The players wearing the shoe with a flexible forefoot outsole demonstrated a decreased perception of comfort in the forefoot cushion compared to regular and stiffer conditions during the comfort test (p < 0.05). The results suggested that the modification of forefoot bending stiffness would influence individual perception of comfort but would not influence performance and lower extremity kinematics during the tested badminton-specific tasks. It was concluded that an optimisation of forefoot structure and materials in badminton shoes should consider the individual’s perception to maximise footwear comfort in performance.     

Acute effect of different minimalist shoes on foot strike pattern and kinematics in rearfoot strikers during running

Despite the growing interest in minimalist shoes, no studies have compared the efficacy of different types of minimalist shoe models in reproducing barefoot running patterns and in eliciting biomechanical changes that make them differ from standard cushioned running shoes. The aim of this study was to investigate the acute effects of different footwear models, marketed as “minimalist” by their manufacturer, on running biomechanics. Six running shoes marketed as barefoot/minimalist models, a standard cushioned shoe and the barefoot condition were tested. Foot–/shoe–ground pressure and three-dimensional lower limb kinematics were measured in experienced rearfoot strike runners while they were running at 3.33 m · s^?1 on an instrumented treadmill. Physical and mechanical characteristics of shoes (mass, heel and forefoot sole thickness, shock absorption and flexibility) were measured with laboratory tests. There were significant changes in foot strike pattern (described by the strike index and foot contact angle) and spatio-temporal stride characteristics, whereas only some among the other selected kinematic parameters (i.e. knee angles and hip vertical displacement) changed accordingly. Different types of minimalist footwear models induced different changes. It appears that minimalist footwear with lower heel heights and minimal shock absorption is more effective in replicating barefoot running.     

国家文化传承视域下民族摔跤的价值注解与历史使命

为探寻民族摔跤在我国数千年传承不断的原因及其所蕴含的崇武尚武价值对国家民生与国运的影响，运用文献资料法、访谈法，以不同历史时期民族摔跤所蕴含的崇武、尚武、强民、强军等特点为切入点进行梳理和剖析。研究表明：民族摔跤被我国历史上强悍游牧文化所推崇，是中华文明史上数个王朝保持民族强盛的秘密武器；民族摔跤所蕴含的民族强盛密码能有效培养国民"威武不屈、爱国无畏"的尚武精神和民族血性；国家注重军队"武勇精神"的培养，是提升士兵的血性、武勇、报国气节，更是决定战争胜负的关键因素。民族摔跤是中华民族优秀文化遗产，新时代应大力发展民族摔跤运动，弘扬中华优秀传统"武"文化，以助力于实现中华民族伟大复兴。     

A structural mechanics model for sports shoes: the heel strike

For a shod heel-striking runner, classical mechanics was used to predict the stresses and displacements for the shoe’s heel, with and without reinforcement. The shoe’s heel loading was based on a typical runner’s measured plantar pressure distribution fitted to a hemispheric pressure dome. Experiments showed that the shoe’s heel region was approximately linearly elastic, so that classical solutions were appropriate for an elastic half-space heel model. Here, the surface dome heel pressure within the heel area and image point loads beyond the heel boundary were superimposed to predict realistic heel boundary stresses and displacements. Results for two limiting boundary conditions were investigated: a vanishing radial boundary stress with maximum lateral heel bulging, and complete suppression of lateral bulging using radial heel reinforcement. The theoretical results herein can serve as guidelines for the development of a new class of running shoes with optimal heel reinforcement between these two boundary limits. This optimisation would lead to more comfortable and efficient running.