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   

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   

“体教结合”视角下体育运动学校“三集中”办学办训模式发展的困境及其对策——以徐汇区青少年体育运动学校为例          下载免费PDF全文

郑昕波  王春秀 《体育科研》2019,(2):49-55

当前在我国培养高水平竞技体育人才的多种方式中，“体教结合”的“三集中”（集中住、集中学、集中训）办学模式占据着独特的优势和特殊的地位。然而，伴随着高考制度的改革，上海市相关人口政策的相继出台，以及家长对子女未来职业选择的多元化趋势等，青少年体育运动学校的“三集中”式办学的主要矛盾凸显。以徐汇区青少年体育运动学校/徐汇位育体校为研究对象，分析学校“体教结合”的“三集中”办学模式发展的瓶颈问题，并对其产生的原因进行解析，进而提出解决“三集中”办学模式发展困境的若干对策及建议。  相似文献   

扩招后我国高校办学规模确定的经济分析   总被引：3，自引：0，他引：3  

宋光辉 《山西财经大学学报(高等教育版)》2004,7(3):17-20

同厂商追求成本最小化策略不同，高校办学者往往存在成本最大化倾向。当达到一定办学规模后，研究型大学更为看重科研，不愿继续扩招，如果继续扩招将导致人才培养质量下降。我们采用多元性线性回归模型，利用教育部直属高校的数据论证了这一结论。从政策上看，目前教育部直属高校不宜继续扩招，扩招的任务应由大量一般院校承担。  相似文献   

“特许学校”重建美国公立学校探析     

李承先  贺武华 《比较教育研究》2008,30(8)

特许学校是美国公立学校重建运动中的一种新形式,它运用市场化、民营化机制对公共教育系统进行体制性重建,1992年以来获得了长足的发展.特许学校在办学经费、规模、分类和立法等方面有其自身特点,尤其在运营机制方面体现出它的独特性.  相似文献   

期刊目标市场策划     

王赛群  陈国民  陈建琼 《湖南城市学院学报》2002,19(3):112-114

从期刊市场的调研、期刊目标市场的开拓方向和确定主要目标市场结构等方面 ,对期刊目标市场策划进行了探讨  相似文献