Effects of mat characteristics on plantar pressure patterns and perceived mat properties during landing in gymnastics

Shock absorption and stability during landings is provided by both, gymnast ability and mat properties. The aims of this study were to determine the influence of different mat constructions on their energy absorption and stability capabilities, and to analyse how these properties affect gymnast's plantar pressures as well as subjective mat perception during landing. Six mats were tested using a standard mechanical drop test. In addition, plantar pressures and subjective perception during landing were obtained from 15 expert gymnasts. The different mats influenced plantar pressures and gymnasts' subjective perception during landing of gymnasts. Significant correlations between plantar pressures at the medial metatarsal and lateral metatarsal zones of the gymnasts' feet with the different shock absorption characteristics of the mats were found. However, subjective perception tests were not able to discriminate mat functionality between the six mats as no significant correlations between the mechanical mat properties with the subjective perception of these properties were found. This study demonstrated that plantar pressures are a useful tool for discriminating different landing mats. Using similar approaches, ideally including kinematics as well, could help us in our understanding about the influences of different mats upon gymnast-mat interaction.     

Effect of shoe wearing time and midsole hardness on ground reaction forces,ankle stability and perceived comfort in basketball landing

ABSTRACT

This study examined the effect of wearing time on comfort perception and landing biomechanics of basketball shoes with different midsole hardness. Fifteen basketball players performed drop landing and layup first step while wearing shoes of different wearing time (new, 2-, 4-, 6- and 8-week) and hardness (soft, medium and hard). Two-way ANOVA with repeated measures was performed on GRF, ankle kinematic and comfort perception variables. Increased wearing time was associated with poorer force attenuation and comfort perception during landing activities (p < 0.05). The new shoes had significantly smaller forefoot (2- and 4-week) and rearfoot peak GRF impacts (all time conditions) in drop landing and smaller rearfoot peak GRF impact (6- and 8-week) in layup; shoes with 4-week of wearing time had significantly better perceptions of forefoot cushioning, forefoot stability, rearfoot cushioning, rearfoot stability and overall comfort than the new shoes (p < 0.05). Compared with hard shoes, the soft shoes had better rearfoot cushioning but poorer forefoot cushioning (p < 0.05). Shoe hardness and wearing time would play an influential role in GRF and comfort perception, but not in ankle kinematics. Although shoe cushioning performance would decrease even after a short wearing period, the best comfort perception was found at 4-week wearing time.     

Modifying landing mat material properties may decrease peak contact forces but increase forefoot forces in gymnastics landings

This study investigated how changes in the material properties of a landing mat could minimise ground reaction forces (GRF) and internal loading on a gymnast during landing. A multi-layer model of a gymnastics competition landing mat and a subject-specific seven-link wobbling mass model of a gymnast were developed to address this aim. Landing mat properties (stiffness and damping) were optimised using a Simplex algorithm to minimise GRF and internal loading. The optimisation of the landing mat parameters was characterised by minimal changes to the mat's stiffness ( < 0.5%) but increased damping (272%) compared to the competition landing mat. Changes to the landing mat resulted in reduced peak vertical and horizontal GRF and reduced bone bending moments in the shank and thigh compared to a matching simulation. Peak bone bending moments within the thigh and shank were reduced by 6% from 321.5 Nm to 302.5 Nm and GRF by 12% from 8626 N to 7552 N when compared to a matching simulation. The reduction in these forces may help to reduce the risk of bone fracture injury associated with a single landing and reduce the risk of a chronic injury such as a stress fracture.     

两种习惯性着地方式对跑步支撑期下肢动力学特征的影响

目的：探究习惯后足着地者和习惯前足着地者在跑步支撑期下肢动力学的不同。方法：采用 Kistler三维测力台（采集力学指标,1 000 Hz）采集受试者跑步支撑期（测试足从足着地到足离地）的动力学数据。结果：习惯后足着地组（RFS）在支撑时间上比习惯前足着地组（FFS）的时间微长,但二者不具有显著差异（P>0.05）;RFS组在支撑期内外方向的最小值和最大值均小于FFS组,且呈显著差异（P＜0.05）;RFS组在支撑期前后方向的最小值（即制动力峰值）和最大值（即加速力峰值）均要高于FFS组,且呈显著差异（P＜0.05）;FFS组在支撑期垂直方向的最大峰值力和第一载荷率均高于RFS组,但不具有显著差异,且出现峰值时间无显著差异（P＞0.05）。结论：跑步时不同的着地方式影响了下肢的生物力学特征,习惯后足着地者跑步支撑期下肢动力学特征与习惯前足着地者主要在内外方向和前后方向上具有一定的差异。     

Relationship of performance on the sensory organization test to landing characteristics

Jump landing tasks have been used to assess landing characteristics and require significant sensorimotor feedback to maintain functional joint stability (FJS) throughout the task. Postural stability (PS) also requires significant sensorimotor feedback and control and would seemingly involve similar sensory feedback pathways. However, previous literature clarifying the relationship between these two processes, maintaining FJS and PS, is limited. 80 Special Tactics Operators. PS was assessed using the Sensory Organization Test (SOT). SOT variables included: Composite, Somatosensory, Visual, Vestibular, and Preference scores. Landing characteristics were assessed using motion analysis during a double-legged (DLSJ) and single-legged (SLSJ) stop jump task. Pearson’s correlation coefficients were calculated to assess the relationship between SOT scores and landing characteristics (α < .05). For the DLSJ, significant correlations were found between: Composite and peak posterior ground reaction forces (?.257), Vestibular and peak knee abduction moment (?.237), and Preference and initial contact hip flexion (?.297), peak hip flexion (?.249). For the SLSJ, significant correlations were found between: Somatosensory and peak vertical ground reaction forces (?.246); Preference and initial contact hip flexion (?.295), peak hip flexion (?.262). The results indicate that the SOT may not be a sensitive enough tool to assess sensorimotor control in a healthy, athletic population.     

Knee joint coordination during single-leg landing in different directions

ABSTRACT

Knee joint coordination during jump landing in different directions is an important consideration for injury prevention. The aim of the current study was to investigate knee and hip kinematics on the non-dominant and dominant limbs during landing. A total of 19 female volleyball athletes performed single-leg jump-landing tests in four directions; forward (0°), diagonal (30° and 60°) and lateral (90°) directions. Kinematic and ground reaction force data were collected using a 10-camera Vicon system and an AMTI force plate. Knee and hip joint angles, and knee angular velocities were calculated using a lower extremity model in Visual3D. A two factor repeated measures ANOVA was performed to explore limb dominance and jump direction. Significant differences were seen between the jump directions for; angular velocity at initial contact (p < 0.001), angular velocity at peak vertical ground reaction force (p < 0.001), and knee flexion excursion (p = 0.016). Knee coordination was observed to be poorer in the early phase of velocity-angle plot during landing in lateral direction compared to forward and diagonal directions. The non-dominant limb seemed to have better coordination than the dominant limb during multi-direction jump landing. Therefore, dominant limbs appear to be at a higher injury risk than non-dominant limbs.     

Effects of a combined inversion and plantarflexion surface on knee and hip kinematics during landing

Although landing in a plantarflexion and inversion position is a well-known characteristic of lateral ankle sprains, the associated kinematics of the knee and hip is largely unknown. Therefore, the purpose of this study was to examine the changes in knee and hip kinematics during landings on an altered landing surface of combined plantarflexion and inversion. Participants performed five drop landings from 30 cm onto a trapdoor platform in three different conditions: flat landing surface, 25° inversion, or a combined 25° plantarflexion and 25° inversion. Kinematic data were collected using a seven camera motion capture system. A 2 × 3 (leg × surface) repeated measures ANOVA was used for statistical analysis. The combined surface showed decreased knee and hip flexion range of motion (ROM) and increased knee abduction ROM (p < 0.05). The altered landing surface creates a stiff landing pattern where reductions in sagittal plane motion are transferred to the frontal plane, resulting in increased knee abduction. A stiff landing pattern is frequently related to increased risk of anterior cruciate ligament injury. It may be beneficial for athletes at risk to train for alternate methods of increasing their sagittal plane motion of the knee and hip with active knee or trunk flexion.     

我国优秀艺术体操人才流动特征研究

运用文献资料法和逻辑分析法,对我国艺术体操优秀人才的流动特征进行研究,结果表明:我国优秀艺术体操人才流动性存在着垂直流动的典型特征;优秀艺术体操人才流动机制尚不成熟是制约我国艺术体操竞技水平发展的重要因素;与其他竞技项目相比艺术体操人才国际流动和水平流动不足。本文对此提出针对性的合理化建议,以期促进我国艺术体操运动长远快速发展。     

Effects of two football stud configurations on biomechanical characteristics of single-leg landing and cutting movements on infilled synthetic turf

Multiple playing surfaces and footwear used in American football warrant a better understanding of relationship between different combinations of turf and footwear. The purpose of this study was to examine effects of shoe and stud types on ground reaction force (GRF) and ankle and knee kinematics of a 180° cut and a single-leg 90° land-cut on synthetic turf. Fourteen recreational football players performed five trials of the 180° cut and 90° land-cut in three shoe conditions: non-studded running shoe, and football shoe with natural and synthetic turf studs. Variables were analyzed with a 3 × 2 (shoe × movement) repeated measures analysis of variance (p < 0.05). Peak vertical GRF (p < 0.001) and loading rate (p < 0.001) were greater during 90° land-cut than 180° cut. For 180° cut, natural turf studs produced smaller peak medial GRFs compared to synthetic turf studs and non-studded shoe (p = 0.012). For land-cut, peak eversion velocity was reduced in running shoes compared to natural (p = 0.016) and synthetic (p = 0.002) turf studs. The 90° land-cut movement resulted in greater peak vertical GRF and loading rate compared to the 180° cut. Overall, increased GRFs in the 90° land-cut movement may increase the chance of injury.     

地表面倾斜度与踝关节护具对垂直着地运动中地面反作用力、踝关节运动学和动力学的效应

研究背景：现有研究文献尚无有关在着地过程中不同表面倾斜度和踝关节护具效应的运动学、动力学和地面反作用力的综合数据。通过对比25°斜面和平面的着地以及使用和不使用踝关节护具情况下来检测踝关节的生物力学特性。研究方法： 11名健康受试者[年龄：（24.6±3.5）岁,身高：（24.6±0.10）m,质量：（65.6±14.9）kg）参与本次研究。受试者在4个动态运动条件下各进行5五次实验：从0.45米高处垂直下落至25°的斜面（IS）或平面（FS）上,使用或不使用半刚性踝关节护具,同时采集三维运动学和测力台地面反作用力数据。利用2×2(表面X踝关节护具)的重复测量方差分析来评估选定的变量。研究结果：与平面着地相比,斜面着地造成较小的垂直和内侧地面反作用力峰值。研究还发现踝关节背曲运动范围、着地角度和背曲速度、最大外翻与跖曲角速度提高,但产生了更大内翻角度和运动范围、着地内翻速度和最大跖曲力矩。踝关节护具在斜面着地时减少了达到地面反作用力第二垂直峰值的时间、着地角度、背曲速度、最大外翻和跖曲速度,但增加了跖曲力矩的最大值。研究结论：斜面增加踝关节额状面的运动范围和踝关节负荷。但是,就斜面着地而言,踝关节护具对踝关节额状面的运动范围和踝关节负荷的影响是相当有限的。     

江苏省业余体校体操运动员调查研究

采用文献资料法、访谈法、问卷调查法等,对江苏省竞技体操后备人才进行了调查研究。结果表明：体操运动员队伍偏小,在训人数太少。运动员文化学习状况让人担忧,已影响了社会心理环境对竞技体操运动后备人才培养的承载能力。     

在体操教学中贯彻"以人为本"和"人文性"的思想

采用文献资料法、逻辑分析法，从现代教学论和体操学科的特点、体操的健身价值三个方面入手，探讨了在体操教学中贯彻“以人为本”和“人文性”观念的理论依据，以及怎样在体操教学中贯彻“以人为本”和“人文性”思想。     

传承与融合——中国武术对古代体操的影响

本研究追溯中国武术与中国古代体操导引术之间深厚的历史渊源和联系,认为两者互相渗透、相互补充,实现了最大的契合和共融。在竞技体育独占鳌头的今天,用中国武术和中国古代体操导引术的概念探寻适合全民健身和健康养生的科学健身之路,将具有很大的积极意义和现实作用。     

竞技体操技术创新与创新能力分析

采用文献资料法和问卷调查法对竞技体操的技术创新与技术创新能力进行了研究,认为技术创新是竞技体操创新活动的核心内容;对技术创新能力的研究是竞技体操科研中的薄弱环节;创新能力由灵感、创新技法、创新实践能力、相关心理品质（想象力、记忆力、观察力等）四部分组成.     

从新奥运周期体操发展态势看我国女子体操薄弱环节及相应对策

以2009年笫41届世锦赛为主要资料,对新奥运周期女子体操发展态势进行研究。结果表明:中美依旧称霸体坛;俄罗斯、罗马尼亚悄然复苏;异军突起实力提升;全能选手是未来大赛竞争资本;竞技体操更趋实力化方向发展。中国女子体操要提高大赛竞争资本,巩固在团体项目上的优势,争取在全能和单项上有所突破,以强大实力迎接新的挑战。     

山东省高校体操教师的教学能力及知识结构

运用献法、专家访谈法、问卷调查法、数理统计法等，对山东省高校体操教师教学能力及知识结构进行了调查研究，发现体操教师的整体教学能力较好，但电化教学能力相对较差，对体育与健康知识的了解、更新方面比较欠缺，根据现状提出了相应的建议。     

体育院系体操教师专业思想的调查分析

对11所体育院系48名体操教师从性圳、职称、教龄和研究方向着手，探讨了目前我国体育院系体操教师的专业思想状况，指出：目前部分体操教师专业思想不稳定，道德水平有待提高；体操教师专业思想状态与教师的性别、教龄无显性差异；体操教师专业思想在不同的研究方向上表现出较大的差异，为稳定教师队伍，进一步深化体操教学改革提供参考。     

新规则周期下世界女子竞技体操发展格局研究

运用文献资料法、录像观察法和数理统计法,对第39届、40届世界体操锦标赛和第29届奥运会女子体操比赛的团体、全能和单项决赛前8名运动员的比赛情况进行分析,结果表明：在新规则周期里世界女子体操的奖牌分布越来越集中;团体与全能的竞争越来越激烈;单项奖牌呈现出垄断性;各国充分显示出自己的特长。     

艺术体操"多元化"发展趋势及其社会化功能

采用跨学科研究的方法，从社会学的角度出发，针对艺术体操“多元化”的发展趋势及其社会化功能进入深入研究，找出制约艺术体操社会化发展的因素，以此科学规范艺术体操的发展趋向，拓宽艺术体操实践的渠道，从而构建艺术体操学科的发展体系，促进这一项目的普及和提高。