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   

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   

竖向电渣压力焊施工操作方法特点     

王作俊 《中国科技信息》2006,(7):137-138

竖向电渣压力焊是一种综合效益极好的技术,具有焊接工艺操作简单、速度快、成本低等特点,应在多层和高层框架结构竖向钢筋连接中大力推行.  相似文献   

To Get What Will Be Lost As Soon As Won——Impression of "Of the Boy and Butterfly" by John Bunyan     

李晓红 《科教文汇》2007,(22)

"Of the Boy and Butterfly" by John Bunyan tells that a boy, greatly attracted by the beautiful colors of a butterfly, got rid of any difficulties he met to catch it, but when finally he got it, he didn't get the pleasure he expected, but felt lost as soon as won. Like the beardless boy, our adults always run after some empty toys, even at all hazards, but when we get them, we find they are but painted nothings and false joys.But we should not be sad, in fact the process of running after is more enjoyable and valuable than the final result, let's enjoy it!  相似文献   

新形势下期刊编辑应具有的办刊理念   总被引：1，自引：0，他引：1  

熊忠 《怀化学院学报》2005,24(3):134-135

在新的形势下,期刊编辑应该具有以读者为本的办刊理念、以市场为导向的经营理念和创造期刊文化的文化理念,具体分析为三个方面:期刊编辑应该具有强烈的读者意识,找准目标读者,树立以读者为本、为读者服务的办刊理念;新形势下的期刊编辑必须增强市场意识,具有以市场为导向的经营理念,把期刊办成高品质的“商品”,接受市场的考验,抓住机遇;期刊编辑还必须具有创造期刊文化的文化理念,必须以创造先进的期刊文化为己任。  相似文献   

铰链四杆机构连杆曲线的图谱     

李文方  高峰 《莆田学院学报》2002,9(3):63-65

根据连杆曲线生成的数学模型,建立了连杆曲线图谱库。该图谱库具有显示轨迹复演和不同连杆点连杆曲线的轮廓形状、变化规律、形成过程及机构各构件的相对运动情况,并可用于机构的尺度综合。  相似文献   

办学理念、办学定位与地方工科院校办学特色建设     

朱其东 《高教论坛》2007,(6):52-54

本文试图在分析地方工科院校办学定位的特色的基础上,提出地方工科院校办学特色建设的关键是办学理念与办学定位特色.  相似文献   

论高职教育的"学校--企业--社会"办学模式   总被引：2，自引：0，他引：2  

闵建杰 《孝感职业技术学院学报》2003,6(3):9-12

发展中国家采取什么样的模式发展高等职业技术教育,是一个有争议的问题,发达国家与地区成功的经验我们不能照搬,必须从国情出发。国内近几年也出现了一些发展高等职业技术教育较为成功的尝试。实践表明,在我国应采取“学校——企业——社会”的办学模式,以学校为主体,或依托企业,或自办企业,或与企业合资,方能使高等职业技术教育得以生存、发展。  相似文献   

基于网络的学习型社会运行模式研究     

华建新  裘伟廷  朱家华 《宁波教育学院学报》2005,7(3):57-61

构建学习型社会是实现和谐社会的重要内容,也是人的生存和发展的必要环境。在信息社会中,利用英特网搭建终身学习的平台,全民参与,是通向学习型社会的重要途径。基于网络的学习型社会运行模式主要有社区运行模式、学校运行模式、行业运行模式、社会团体运行模式等。高效、实用、灵活的网络学习运行模式是构建学习型社会的基本保证。  相似文献