Joint work is not shifted proximally after a long run in rearfoot strike runners     

Jake A. Melaro  Allison H. Gruber 《Journal of sports sciences》2021,39(1):78-83

ABSTRACT

Distal-to-proximal redistribution of joint work occurs following exhaustive running in recreational but not competitive runners but the influence of a submaximal run on joint work is unknown. The purpose of this study was to assess if a long submaximal run produces a distal-to-proximal redistribution of positive joint work in well-trained runners. Thirteen rearfoot striking male runners (weekly distance: 72.6 ± 21.2 km) completed five running trials while three-dimensional kinematic and ground reaction force data were collected before and after a long submaximal treadmill run (19 ± 6 km). Joint kinetics were calculated from these data and percent contributions of joint work relative to total lower limb joint work were computed. Moderate reductions in absolute negative ankle work (p = 0.045, Cohen’s d = 0.31), peak plantarflexor torque (p = 0.004, d = 0.34) and, peak negative ankle power (p = 0.005, d = 0.32) were observed following the long run. Positive ankle, knee and hip joint work were unchanged (p < 0.05) following the long run. These findings suggest no proximal shift in positive joint work in well-trained runners after a prolonged run. Runner population, running pace, distance, and relative intensity should be considered when examining changes in joint work following prolonged running.  相似文献   

Effect of different loading conditions on running mechanics at different velocities     

Germán Carretero-Navarro  Doménico Cherubini  Wolfgang Taube 《European Journal of Sport Science》2019,19(5):595-602

Weighted vests are widely used to improve running economy and performance. However, it is not well-studied how running mechanics are adapted to counteract the higher peak vertical ground reaction forces (Fpeak) while running with such a device. Therefore, the present study aimed to investigate the effects of different loading conditions on running mechanics at different velocities. Thirteen subjects participated in two separate sessions one week apart. In the first session, maximal aerobic speed (MAS) was determined through a maximal incremental running test while in the second session, they were instructed to run during one minute under different loading (0%, +10% and +20% of body mass [BM]) and velocity (60%, 80% and 100% of MAS) conditions in a random order. Spatiotemporal data were recorded and then running mechanics modelled using the spring-mass model. The main results indicated that vertical and leg stiffness (Kvert and Kleg, respectively) were increased (P?P?>?.05) when load was changed. At the same time, alterations of the running kinematics were observed such as longer contact times, reduced flight times, stride frequencies and step lengths, as well as an increase of the centre of mass dynamics. Based on these results it is assumed that runners maintain a certain stiffness level for each velocity despite different loading conditions. As a consequence, Fpeak increases and this probably causes spatiotemporal adjustments in the movement kinematics.  相似文献   

Analysis and evaluation of lecturers’ activity in Learning Management Systems: Subjective and objective perceptions     

Magdalena Cantabella  Belén López  Alberto Caballero 《Interactive Learning Environments》2018,26(7):911-923

Learning Management Systems (LMS) have become the principal resource for the distribution of educational material and collaboration among lecturers and students in Higher Education. The potential of these platforms does not limit to a simple manager of contents, but they also offer a wide range of tools that support the development of different methodologies according to the learning modality, namely on-campus, blended or online. This work analyzes the use of LMS and the interactions with their different tools from the lecturers’ point of view, in order to detect possible incidents, check the tools’ utility and evaluate their complexity. All these metrics represent valuable information to the Degree Coordinators, if they are presented in a suitable manner, to detect and resolve deficiencies in the methodology. For the analysis of the teaching activity two methods are employed: (1) surveys, to measure the subjective perception of lecturers when using LMS tools; and (2) visual analysis of the real lecturer’s activity through OnlineData, a graphical analytic tool developed as part of our work to monitor LMS tools metrics. The results of both methods show differences among the perceived self-usage and actual usage, especially for the e-learning methodologies  相似文献   

我国高尔夫球奥运选手与世界优秀选手一号木数据对比分析     

赵紫龙 《河北体育学院学报》2020,34(6):85-90

采用文献资料法、实地考察法、数理统计法和对比分析法，对我国奥运选手和世界优秀选手的一号木数据进行分析。发现，在实地考察的球洞中，世界优秀选手全四轮均使用一号木开球，而我国男子选手则是一号木、三号木交替开球，可能是由于对自身一号木开球技术不够自信；我国男子选手的一号木平均开球距离、上球道率较世界优秀选手均差距较大；我国女子选手的一号木平均开球距离与世界优秀选手较为接近，但上球道率有待提高。建议，男子选手加强开球距离和上球道率的训练，女子选手加强上球道率的训练；冯珊珊进一步提升开球距离；在比赛前要对场地进行多次熟悉，找到合适的开球策略。  相似文献   

Leg amputation side determines performance in curve sprinting: a case study on a Paralympic medalist     

Johannes Funken  Kai Heinrich  Steffen Willwacher  Ralf Müller  Jonas Böcker  Hiroaki Hobara 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(1):75-87

The lower limb kinetics of curve sprinting in amputees are not well described in the literature, particularly with respect to the effect of the side of amputation. This is an issue due to the importance of the knowledge for prosthetic design and classification of athletes. Thus, the aim of this study was to investigate the influence of side of amputation on curve sprinting performance in athletes with a unilateral leg amputation. A three-dimensional motion analysis system (Vicon), four force plates (Kistler) and a modified mathematical human model (ALASKA) were used to compare clockwise and counter clockwise curve sprinting lower limb kinematics and kinetics of a Paralympic medalist with a left-sided knee exarticular amputation. Results reveal that vertical ground reaction force application and total vertical impulse were lower when the affected limb was at the inside of the curve. The unaffected limb showed joint mechanics different to those established for non-amputee athletes and might contribute better to propulsion when being the inside limb. Curve sprinting biomechanics and the ability to attain high radial velocities are directly dependent on the side of amputation relative to the curve direction in a unilateral amputee athlete of highest performance level.  相似文献   

Russians are the fastest and the youngest in the “Comrades Marathon”     

Pantelis T. Nikolaidis 《Journal of sports sciences》2019,37(12):1387-1392

The present retrospective study intended to determine age, performance, the role of nationality and participation trends across calendar years in runners competing in “Comrades Marathon”, the ultra-marathon with the longest tradition and the highest number of finishers worldwide. We analysed 235,467 finishers (40,211 women and 195,256 men) competing between 1994 and 2017. In women and men, Russians were the fastest (12.55 ± 2.03 km/h and 12.24 ± 2.93 km/h, respectively) and Indians the slowest (7.87 ± 0.64 km/h and 7.91 ± 0.60 km/h) (p < 0.001, η2 = 0.053 and η2 = 0.010, small effect size, ES). Also, Russians were the youngest (33.9 ± 4.6 and 36.3 ± 5.9 years, respectively) and Japanese the oldest (49.3 ± 9.6 and 51.4 ± 12.3 years, respectively) (p < 0.001, η2 = 0.011, small ES). Performance improved (r = 0.90 in women and r = 0.92 in men), age of finishers (r = 0.91 in women and r = 0.97 in men), participation (r = 0.92 in women and r = 0.87 in men) and sex difference in age increased (r = 0.71), whereas men-to-women ratio (r = ?0.91) and sex difference in performance (r = ?0.68) decreased across calendar years (p < 0.001). In summary, runners from Russia were the fastest and the youngest in both sexes. The knowledge of the relationship of nationality with performance, age and participation trends of finishers, and changes across calendar years are of practical importance for ultra-runners and coaches working with them.  相似文献   

草根体育组织规范化发展研究——以我国跑团为例     

王相飞  蔡平原  延怡然 《武汉体育学院学报》2019,53(9):28-34

以我国草根组织中的典型组织——跑团为例，分析了我国跑团兴起的主要原因，发展过程中存在的问题：跑团内部机制不健全，治理方式滞后；缺乏稳定的社会资源；政府职能部门引导、扶持不力；相关的规章制度、法律不够完善；较难获得合法身份致使发展受阻，缺少主管单位监督和行业自律；跑团存在多种安全隐患；对于各种跑团社交软件及社交平台的管理不够。据此提出了对策：对跑团进行分级分类管理，充分发挥中国田协的指导与监督作用，政府部门不断完善跑步公共服务体系，加强跑团制度建设与规范管理，健全安全健康监管保障体系。  相似文献   

The biomechanical characteristics of high-performance endurance running     

Stephen J. Preece  Christopher Bramah  Duncan Mason 《European Journal of Sport Science》2019,19(6):784-792

The biomechanical profile of high-level endurance runners may represent a useful model that could be used for developing training programmes designed to improve running style. This study, therefore, sought to compare the biomechanical characteristics of high-performance and recreational runners. Kinematic and kinetic measurements were taken during overground running from a cohort of 14 high-performance (8 male) and 14 recreational (8 male) runners, at four speeds ranging from 3.3 to 5.6?m?s^?1. Two-way ANOVA analysis was then used to explore group and speed effects and principal component analysis used to explore the interdependence of the tested variables. The data showed the high-performance runners to have a gait style characterised by an increased vertical velocity of the centre of mass and a flight time that was 11% longer than the recreational group. The high-performance group were also observed to adopt a forefoot strike pattern, to contact the ground with their foot closer to their body and to have a larger ankle moment. Importantly, although observed group differences were mostly independent of speed, the tested variables showed a high degree of interdependence suggesting an underlying unitary phenomenon. This is the first study to compare high-performance and recreational runners across a full range of kinematic and kinetic variables. The results suggest that high-performance runners maintain stride length with a prolonged aerial phase, rather than by landing with a more extended knee. These findings motivate future intervention studies that should investigate whether recreational runners could benefit from instruction to decrease shank inclination at foot contact.  相似文献   

Acute kinematics changes in marathon runners using different footwear     

Tania Socorro Amorim Soares  Federico Pizzuto  Rui Manuel Garganta  João Paulo Vila-Boas  Mario Casimiro da Anunciação Paiva 《Journal of sports sciences》2018,36(7):766-770

The effects of running with or without shoes on injury prevention have been extensively studied, and several investigations have assessed biomechanical differences between them. However, findings are not consensual and further insights on biomechanical load associated with differently shod or barefoot conditions may be needed. This study aimed to observe if habitually shod marathon runners show acute alterations when running barefoot or with minimalist shoes, and to determine whether the running kinematical adaptations of wearing minimalist shoes were similar to barefoot running. Twelve male marathon runners ran on the treadmill at their average marathon pace in different footwear conditions: habitual running shoes, minimalist shoes, and barefoot. High-resolution infrared cameras and visual 3D software were used to assess kinematic data. The following parameters were studied: foot strike angle, cycle time, stance time, normalized stride length, hip, knee, and ankle angular position at initial contact, and their respective range-of-motion (ROM) during stance phase. Contrary to the expectations, it was found that highly trained habitually shod elite marathon runners changed their lower limb kinematic pattern both when running barefoot or wearing minimalist shoes. Minimalist shoes showed a trend towards intermediate biomechanical effects between running with and without shoes.  相似文献   

心理距离视角下网络舆情传播意愿影响因素研究   总被引：1，自引：1，他引：0  

张晓君  黄微  李瑞 《图书情报工作》2019,63(12):86-93

[目的/意义]网络舆情传播意愿的形成是网民的一种心理活动，与心理距离密不可分。了解影响网络舆情传播意愿的主要因素，有助于监督管控部门更加卓有成效地对网络舆情进行预警和治理。[方法/过程]通过对心理距离理论的深层次剖析，对其构成进行阐述，并从时间距离、空间距离、社会距离、概率4个维度出发，做出系列理论假设，利用调查问卷法和最优尺度回归分析法，识别出主要影响因素及其重要程度。[结果/结论]最终归纳出7个影响网民改变其自身传播意愿的主要因素，即报道时间、家乡相关、向往地相关、生活相关、亲戚朋友发布、媒体官方发布、企业官方发布，从这7个影响因素出发监控舆情，可以帮助舆情管控部门更有针对性地掌控舆情的传播方向。  相似文献