Increased foot-stretcher height improves rowing performance: evidence from biomechanical perspectives on water     

Yang Liu  Binghong Gao  Jiru Li  Zuchang Ma  Yining Sun 《Sports biomechanics / International Society of Biomechanics in Sports》2020,19(2):168-179

Abstract

The aim of this study was to investigate whether changes on foot-stretcher height were associated with characteristics of better rowing performance. Ten male rowers performed a 200 m rowing trial at their racing rate at each of three foot-stretcher heights. A single scull was equipped with an accelerometer to collect boat acceleration, an impeller with embedded magnets to collect boat speed, specially designed gate sensors to collect gate force and angle, and a compact string potentiometer to collect leg drive length. All sensor signals were sampled at 50 Hz. A one-way repeated measures ANOVA showed that raising foot-stretcher position had a significant reduction on total gate angle and leg drive length. However, a raised foot-stretcher position had a deeper negative peak of boat acceleration at the catch, a lower boat fluctuation, a faster leg drive speed, a larger gate force for the port and starboard side separately. This could be attributed to the optimisation of the magnitude and direction of the foot force with a raised foot-stretcher position. Although there was a significant negative influence of a raised foot-stretcher position on two kinematic variables, biomechanical evidence suggested that a raised foot-stretcher position could contribute to the improvement of rowing performance.  相似文献   

New curve sprint test for soccer players: Reliability and relationship with linear sprint     

Alberto Fílter  Jesús Olivares  Alfredo Santalla  Fabio Y. Nakamura  Irineu Loturco  Bernardo Requena 《Journal of sports sciences》2020,38(11-12):1320-1325

ABSTRACT

The speed performance is involved not only in linear sprints, but also in a wide spectrum of multi-directional movements, such as curve sprinting. Curved sprint can be defined as sprint with gradual and continuous change of direction (COD). Although ~85% of the actions performed at maximum velocity in a professional soccer league are curvilinear sprints, there is not any specific test to assess this ability. This study aimed to analyse the reliability of a new curve sprint test, and compare its results with those obtained by soccer players in linear sprint. Forty experienced soccer players performed 3 attempts of curve sprint (using the penalty arc) to right and left side (17 m), and 3 linear sprints (17 m) in two different days. The ICCs (inter-session reliability) were 0.93 for sprint curve right side (CSRS) and 0.89 for sprint curve left side (CSLS), considered “acceptable”. The CVs (intra-session reliability) were 0.87% in CSRS and 1.15% in CSLS. The coefficient of determination (R²) between linear and curve sprinting was ~35%. The association between curve sides was “very large” (r = 0.878; p < 0.01). In summary, we showed that “curve sprint test” is highly reliable, and that curvilinear and linear sprints are different and independent actions.  相似文献   

Evaluation of soccer players under the Moneyball concept     

Luiz Octávio Gavião  Annibal Parracho Sant’Anna  Gilson Brito Alves Lima  Pauli Adriano de Almada Garcia 《Journal of sports sciences》2020,38(11-12):1221-1247

ABSTRACT

The recruitment of athletes with limited resources is a global problem in professional sports. In US Major League Baseball, the experience of the Oakland Athletics’ general manager in the last decade turned his “Moneyball” model into a synonym of quantitative analysis in the transfer market of baseball players. His strategy focused on hiring players with outstanding technical skills but relatively low market value. This study adapted this model to the framework of a multiple criteria decision aid (MCDA), by selecting undervalued players who have complementary abilities. The novelty here refers to the joint use of four algorithms explored by the composition of probabilistic preferences (CPP) (i.e., ranking, classification, dynamic evaluation and regularity analysis) and their application to soccer player performance evaluation. The new model analysed the recent transfer of a left-back soccer player to Europe. The results indicated 12 opportunities for better investment, among 32 left and right-back players considered. Two years later, the value of the same player was considerably lower. He played only five matches in the 2018–2019 season, without scoring or providing any assists. On the other hand, the players better classified by the CPP-MB model presented higher performances and market values.  相似文献   

Antecedents and consequences of social media fatigue     

《International Journal of Information Management》2019

Prior literature suggests that social media users are increasingly experiencing social media fatigue. Only recently have scholars undertaken empirical studies to investigate its antecedents and outcomes to better understand the impact of fatigue on social media users. To further this understanding, the present study has conducted a cross-sectional survey with 1552 users. The Stress-Strain-Outcome (SSO) theoretical framework is applied to examine if privacy concerns, self-disclosure, parental mediation strategies, and decrement in academic performance due to social media use correlate with social media fatigue. Two forms of fatigue are considered, namely, fatigue due to social networking site (SNS) and mobile instant messaging (MIM) use. The study results suggest that privacy concerns, self-disclosure, parental encouragement and worry significantly and positively correlate with SNS and MIM fatigue. Parental permission and parental monitoring are either not or lowly associated with fatigue. In addition to this, SNS and MIM fatigue positively correlated with the tendency to experience academic decrement due to social media use. The antecedents and consequences of social media fatigue were similar for SNS and MIM users. Moreover, students perceived their parents to be more open to their MIM use, and they had higher self-disclosure in MIM than in SNS. The study concludes with significant implications for practitioners, policy makers as well as service designers.  相似文献   

力量功能训练常见方法简析     

胡胜 《当代体育科技》2020,(12):51-51,53

本文通过综述几种常见的力量功能训练方法,为提高运动训练成绩和大众体质健康健身服务。近年来,力量训练方法越来越多,有速度力量和耐力力量训练。常见的力量训练功能训练有振动训练、PNF训练、悬吊训练、超等长训练、本体感觉与核心训练。力量训练通常与速度、敏捷、耐力和反应训练密切相关,适时加强与力量有关的素质练习尤为重要,只有这样才能提高力量训练的效果,保持运动成绩,以力量为基础的功能训练衍生出来多种训练方法,本文对这些方法梳理和总结,为后人研究学习提供方便。  相似文献   

Real-time analytics,incident response process agility and enterprise cybersecurity performance: A contingent resource-based analysis     

《International Journal of Information Management》2021

Emerging paradigms of attack challenge enterprise cybersecurity with sophisticated custom-built tools, unpredictable patterns of exploitation, and an increasing ability to adapt to cyber defenses. As a result, organizations continue to experience incidents and suffer losses. The responsibility to respond to cybersecurity incidents lies with the incident response (IR) function. We argue that (1) organizations must develop ‘agility’ in their IR process to respond swiftly and efficiently to sophisticated and potent cyber threats, and (2) Real-time analytics (RTA) gives organizations a unique opportunity to drive their IR process in an agile manner by detecting cybersecurity incidents quickly and responding to them proactively. To better understand how organizations can use RTA to enable IR agility, we analyzed in-depth data from twenty expert interviews using a contingent resource-based view. The results informed a framework explaining how organizations enable agile characteristics (swiftness, flexibility, and innovation) in the IR process using the key features of the RTA capability (complex event processing, decision automation, and on-demand and continuous data analysis) to detect and respond to cybersecurity incidents as-they-occur which, in turn, improves their overall enterprise cybersecurity performance.  相似文献   

督导视角下的高校绩效监控分析     

《辽宁教育研究》2014,(8)

督导作为一种人本主义管理思想和方法,是管理科学发展到一定阶段才出现的。将督导方法用于高校的绩效管理和监控工作中,既是对企业绩效监控的超越,也是绩效监控方式和观念的新发展。高校实行绩效管理的成功保障便在于建立完善的督导体系,明确绩效督导的内容,并按照督导逻辑付诸实施。  相似文献   

有氧能力关联基因多态与技巧类滑雪运动员跨项选材     

周文婷 《武汉体育学院学报》2019,53(6):66-71

目的：研究优秀技巧类滑雪运动员中4个有氧能力关联多态基因ACE、GLUT4、ADRB2和PPARGC1A的分布频率，及基于4个优势等位基因的基因型总分（TGS），探索上述多态基因与TGS作为我国优秀技巧类滑雪运动员跨项选材分子标记的可行性。方法：应用基质辅助激光解吸附电离飞行时间质谱检测技术，对68名中国北方汉族优秀技巧类滑雪运动员与138名中国北方汉族普通大学生ACE基因rs4340位点、GLUT4基因rs5418位点、ADRB2基因rs1042713位点和PPARGC1A基因rs8192678位点进行解析。计算并比较运动员与对照组在上述4个位点的TGS。结果：在上述4个多态位点，运动员与对照组间的基因型和等位基因频率无显著性差异（P>0.05）；两组人在携带的优势等位基因数量、TGS分值范围、平均TGS分值及TGS分值的分布频率上也均无显著性差异（P>0.05）。结论：ACE基因rs4340位点、GLUT4基因rs5418位点、ADRB2基因rs1042713位点、PPARGC1A基因rs8192678位点多态性和基于上述4个位点的TGS均无法作为中国北方汉族技巧类滑雪运动员的有氧能力跨项分子选材标记。  相似文献   

Effects of an aerobic fitness test on short- and long-term memory in elementary-aged children     

Jennifer L. Etnier  Paul M. Sprick  Jeffrey D. Labban  Chia-Hao Shih  Stephen M. Glass  Jarod C. Vance 《Journal of sports sciences》2020,38(19):2264-2272

ABSTRACT

Meta-analytic evidence supports that exercise has benefits for short-term memory (STM) and long-term memory (LTM). However, only three studies with children have tested the differential effects of exercise on STM and LTM. The purpose of this study was to examine the effects of an aerobic fitness test on STM and LTM and to consider the moderating effects of grade level. Children (7–13 years of age) were randomly assigned to either perform an aerobic fitness test before (exercise prior) or after (exercise post) performing the Rey Auditory Verbal Learning Test (RAVLT) to assess memory. Memory was tested again after approximately 24 hours. There were significant differences in memory performance as a function of grade with 4^th and 6^th graders consistently outperforming 2^nd graders. For learning, Day 1 Retention, 24-hr recall, and Day 2 Retention, the exercise prior group performed better than the exercise post group. It is concluded that an aerobic fitness test performed prior to a declarative memory test benefits LTM as compared to when the aerobic fitness test is performed after the memory test.  相似文献   

Towards a Framework for Evaluating the Research Performance of Chinese Double First-Class Universities     

XU Changqing 《Frontiers of Education in China》2020,15(3):369

The study focuses on the research performance of Double First-Class (DFC) universities in China. A theoretical framework based on economic theory and the Analytic Hierarchy Process (AHP) method for a novel evaluation model is proposed. The model is performed on a sample of 41 participant DFC universities in China. Using data collected from these universities, it was found that there is no consistency between performance ranking, input ranking, and output ranking, with the best ranked universities far from the most efficient. These findings provide empirical evidence of DFC universities’ research performance situation and suggest strategies that the government can use to propel their sustainable development.  相似文献